3. us0 [i r. f. [xi [i ,h [i s,/67531/metadc... · whc-sd-ff-cser-004 rev 1 page 1 criticality...

ENGINEERING CHANGE NOTICE 3 of 3

18.944

2. ECN Category (mark one)

I ..... . . ............ . . .. Proj. ECN

3. Or ig ina to r ’ s Name, Organization, MSIN. 4. US0 Required? 5. Date and TeleDhone No.

R. F. Richard, Criticality and Shielding, HO-35, 376-9955 , ,

,h 9. Docment Nunbers Changed by t h i s ECN

( inc ludes sheet no. a rd rev.)

WHC-SD-FF-CSER-004, Rev. 0

Supplemental [I Di rec t Revision [X I Change ECN [I Temporary [I Standby [I Supersedure [I Cancellvoid [I

[ I Yes [XI NO October 7, 1996

7. Bldg./Sys.lFac. NO. 8. Approval Designator

FFTF s, P 10. Related ECN No(s). 11. Related PO No.

_ _ _ _-_ 12a. Mod i f i ca t i on Work

[ ] Yes ( f i l l out Blk. 12bl

12b. Work Package NO.

W A

12c. Modi f icat ion Work Complete 12d. Restored t o Or ig ina l Cordi- t i o n (Temp. or Standby ECN only)

N I A N J A

Design AuthoritylCog. Engineer Signature & Date 12c. 1Zd)

14a. J u s t i f i c a t i o n (mark one)

C r i t e r i a Change [XI Design Improvement [ ] E n v i r a m n t a l [ ] F a c i l i t y Deact ivat ion [ I Ls-Found [ ] F a c i l i t a t e Const [ ] Const. Errorfomission [ ] Design Error lomiss ion [ ] 14b. J u s t i f i c a t i o n De ta i l s

A moderated Core Component Container (CCC) with full reflection, when loaded with five pin containers in the outer tubes and two fuel assemblies in the remaining tubes, has a keff below 0.95 plus bias and uncertainty. containers plus two fuel assemblies in a CCC is acceptable, with the restriction that no pin container is allowed in the center storage tube.

Therefore, allowing up to five pin

Design AuthoritylCog. Engineer Signature & Date

15. D i s t r i b u t i o n ( i nc lude name, K I N , and no. o f copies)

See attached Distribution.

A-7900-013-2 (05/96) GEFO95

A-7300-013-1 l11/881

ENGINEERING CHANGE NOTICE of Z

Functional Design Crtttrria

Operating Specification

Criticality Specification

Conceptual Design Report

Equipment Spec.

const. spec.

Pmcursmsnt Spec.

Vendor information

OM Manual

FSARISAR

Safety Equipment List

Radiation Work Permit

Environmsntal Impact Statement

Environmental Report

Environmental Permit

1. ECN (use no. from pg. 1)

186725

SaismiclStrass Analysis

StmssIDesign Report

Interface Contml Drawing

Calibration Procedure

Installation Procedure

Maintenance Pmcsdura

Engineering Procedure

Operating Instruction

Operating Procedum

Operational Safsty Requirement

IEFD Drawing

Cell Anangsmmt Drawing

Essential Material Specification

Fao. Prom. Samp. Schedule

Inspection Plan

Inventory Adjustment Request

16. Design V e r i f i c a t i o n Required

11 Yes

[XI No

. .. Tank Calibration Manual

17. Cost Impact 18. Schedule Impact (days) ENGINEERING CONSTRUCTION

Improvement 11 [ I Delay

[ I 6 [ I $

Addit ional

Savings [ I $ .[I $

Add i t iona l

Savings

Health Physics Procedure

Sparsa Multiple Unit Listing

Test Procsdursslspacification

Component Index

ASME Coded Item

Human Factor Consideration

Computer Soitware

Electric Circuit Schedule

ICRS Pmcsdura

Pmcass Control ManuallPlan

Process Flow Chart

Purchase Requisition

Tickler File

[ I [ I 20. Other A f fec ted Documents: (NOTE: DOcUnents l i s t e d below w i l l not be revised by t h i s ECN.) Signatures below

ind ica te that the s ign ing organization has been n o t i f i e d of other affected documents l i s t e d below. Oocunent NumberlRevision Docunent Nunber/Revision Document Nunber Revision

21. Approvals

Signature Design Author i ty

Date

Cog. Eng. R. F. Richard

IO -%-9L Environ.

/0-(1-96 Tech. Rev. K. D. Dobbin

C r i t . S f t y Rep. J. E. Baker 10 -8 -Qg

Signature Design Agent

PE QA

Safety

Design

Environ.

Other

DEPARTMENT OF ENERGY

Signature or a Control Nm6er that tracks the Approval Signature

ADDITIONAL

Date

A-7900-013-3 (05/96) GEF096

A-39 Rev. 1 Appendix B Page B1

APPENDIX B

UNREVIEWED SAFETY QUESTION SCREENING FORM

REFERENCE ITEM # ECN 186725

TITLE Chanse t o C r i t i c a l i t v Safe ty E v a l u a t i o n ReDort WHC-SD-FF-SCER-004

QUESTIONS Does t h e re fe renced i tem: A. Make PROPOSED CHANGES t o t h e f a c i l i t y o r procedures which d i f f e r f rom

c o n d i t i o n s descr ibed i n t h e AUTHORIZATION BASIS?

N/A- No& Yes/Maybe-

rocedures. It i s an a n a l v s i s / e v a l u a t i o n which w i l l then be used t o i u s t i f v chanqes t o o t h e r documents. These o t h e r documents le .q . C r i t i c a l i t v Prevent ion S D e c i f i c a t i o n l w i l l r e a u i r e a US0 e v a l u a t i o n f o r comDarison w i t h t h e c u r r e n t FSAR.

B. Descr ibe an ISSUE which d i f f e r s f rom those descr ibed events o r

c o n d i t i o n s i n t h e AUTHORIZATION BASIS? N / A X No- YeslMaybe-

Basis:

C . Descr ibe t e s t s o r experiments which d i f f e r f rom those descr ibed i n t h e AUTHORIZATION BASIS? N / A X No- YeslMaybe-

Bas is :

NOTE: T h i s form i s n o t t o be used f o r PHYSICAL PLANT MODIFICATIONS.

QUSQE #1 W. A. Dautel

Date 10/9/96

QUSQE #2 P. R. Prevo ( p r i n t name)

Date 10/9/96 S ig f ia tu re '

ZGd I Sb?21 p&y c 3

8 WHC-SD-FF-CSER-004, Rev. 1

Criticality Safety Evaluation for Long Term Storage of FFTF Fuel in Interim Storage Casks

R. F. Richard Westinghouse Hanford Company, Richland, WA 99352 U.S. Department o f Energy Cont rac t DE-AC06-87RL10930

EDT/ECN: 186725 uc: 533 Org Code: 403 Charge Code: B193D B&R Code: EX7003000 T o t a l Pages: 46

Key Words: Core Component Container, CCC, C r i t i c a l i t y , FFTF, I n t e r i m Storage Area, I S A

A b s t r a c t : T h i s C r i t i c a l i t y Safe ty Eva lua t ion a l l o w s a mix o f up t o f i v e p i n c o n t a i n e r s p l u s two assemblies i n t h e same Core Component Conta iner .

TRADEMARK DISCLAIMER. trade name, trademark, manufacturer, or otherwise, does not necessari ly c o n s t i t u t e or imply i t s endorsement, recomnendation, or favoring by the United States C o v e r m n t or any agency thereof or i t s .con t rac tors or subcontractors.

Reference here in t o any s p e c i f i c conmercial product, process, or serv ice by

P r i n t e d i n the United States of America. To obta in copies of t h i s document. contact: UHC/BCS

Fax (509) 376-4989. D o c m n t Controt Services, P.O. Box 1970, Mailstop H6-08,

STA.

Release Stamp

Approved for Public Release

A-6400-073 (10/95) CEF321

WHC-SD-FF-CSER- 004

RECORD OF REVISION

(2) T i t l e

C r i t i c a l i t y S a f e t y E v a l u a t i o n f o r Long Term Storage o f FFTF Fuel i n I n t e r i m Storage Casks I

Page 1

(3) Revision

0 1 Reissue e n t i r e document p e r ECN # 186725 R.F. R ichard J

RS R.F: u ~1.96 II . A -

(4) Description o f Change - Replace, Add, and Delete Pages Authorized for Release ( 5 ) Cog. Engr. I ( 6 ) Cog. Mgr. Date

(7) I n i t i a l Release EDT # 605970

A-7320-005 (08/91) WEF168

WHC-SD-FF-CSER-004 REV 1 Page 1

CRITICALITY SAFETY EVALUATION FOR LONG TERM STORAGE OF FFTF FUEL I N INTERIM STORAGE CONTAINERS

Prepared by : R.F: rLL-4 I 0 -7-46 R. F. Richard, Advanced Engineer Date C r i t i c a l i t y & S h i e l d i n g

Reviewed by: L?L? u t0-8-9b J". N. P a g l i e r i , P r i n c i p a l Engineer FFTF Safe ty

Date

/ d - 8-?L J. Baker, P r i n c i p a l Engineer Date FF F C r i t i c a l i t y Safe ty Representa t ive

14. i3 %&& 10-S-YL

Approved by: lo/ 8/96

K. 0. Dobbin, P r i n c i p a l Engineer Date

a/ Greenborg, Manag ' 'Date

W-B-?G R. 0. Z-i-dmerman, Team Leader FFTF Safe ty

Date


CONTENTS

1.0 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2.0 SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

3.0 FUEL AND CONTAINER DESCRIPTIONS . . . . . . . . . . . . . . . . . . . 4

4.0 ANALYSIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

4.1 Previous Analyses . . . . . . . . . . . . . . . . . . . . . . . . 5 4.2 Seven Fuel Assemblies i n a CCC . . . . . . . . . . . . . . . . . 9 4.3 M u l t i p l e I S C Storage . . . . . . . . . . . . . . . . . . . . . . 11

5.0 RESULTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

5.1 Hot C e l l Rot . . . . . . . . . . . . . . . . . . . . . . . . . . 11 5.2 Seven Ident-69s i n an CCC . . . . . . . . . . . . . . . . . . . . 16 5.3 M u l t i p l e ISC Storage . . . . . . . . . . . . . . . . . . . . . . 17 5.4 C r i t i c a l Number . . . . . . . . . . . . . . . . . . . . . . . . . 18

6.0 CONCLUSIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

7.0 VALIDATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

8.0 REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

APPENDIXA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

APPENDIXB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

APPENDIXC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41


CRITICALITY SAFETY EVALUATION FOR LONG TERM STORAGE OF FFTF FUEL I N INTERIM

STORAGE CASKS

1.0 INTRODUCTION

I n t h e c u r r e n t p l a n f o r l o n g term, i n t e r i m , s to rage o f i r r a d i a t e d FFTF f u e l , t h e f u e l assemblies w i l l be washed, and p laced i n Core Component Conta iner (CCC) assemblies which, i n t u r n , w i l l be p laced i n I n t e r i m Storage Casks ( ISC). (ISA) t h a t i s l o c a t e d a t t h e n o r t h e a s t corner o f t h e 400 p r o p e r t y p r o t e c t i o n area. Each CCC can accommodate up t o seven FFTF f u e l assemblies o r s i x p i n c o n t a i n e r s . M i x i n g up t o seven f u e l assemblies and p i n c o n t a i n e r s i n a CCC i s a l lowed w i t h t h e f o l l o w i n g 2 r e s t r i c t i o n s : t h e r e can be no p i n c o n t a i n e r i n t h e c e n t e r s to rage tube and no more than f i v e p i n c o n t a i n e r s a re a l lowed i n a CCC w i t h mix ing . Previous analyses (R ichard 1994, Er ickson 1993, Wi lcox 1991, Wi lcox 1989) have shown t h a t s to rage o f s i x FFTF f u e l assemblies o r s i x p i n c o n t a i n e r s i n CCCs i s acceptable f rom a n u c l e a r c r i t i c a l i t y s a f e t y p e r s p e c t i v e . T h i s document does n o t address Type B assemblies; they w i l l be addressed i n a separate document. Exper imental assemblies w i l l be eva lua ted on a case by case b a s i s .

The ISCs w i l l be p laced on a concre te pad a t t h e I n t e r i m Storage Area

2.0 SUMMARY

It has been p o s t u l a t e d (Waltar, 1993) t h a t a degradat ion phenomenon, r e f e r r e d t o as " h o t c e l l r o t " , may a f f e c t i r r a d i a t e d FFTF mixed plutonium-uranium ox ide (MOX) f u e l d u r i n g d r y i n t e r i m storage. "Hot c e l l r o t " r e f e r s t o a v a r i e t y o f phenomena t h a t degrade f u e l p i n c l a d d i n g d u r i n g exposure t o a i r and i n e r t gas environments. o r env i ronmenta l l y a s s i s t e d c rack ing . occurrence o f t h i s phenomenon; however, f o r conservat ism, extreme cases o f complete assembly d i s i n t e g r a t i o n were analyzed t o ensure a c r i t i c a l i t y sa fe c o n f i g u r a t i o n . t h a t may occur.

It i s thought t o be a form o f c a u s t i c s t r e s s c o r r o s i o n c r a c k i n g Steps w i l l be taken t o p revent t h e

The geometr ies analyzed bound any reasonable c o n f i g u r a t i o n

The kef, o f t h e most r e a c t i v e c o n f i g u r a t i o n analyzed ( w i t h o u t a l l o w i n g f o r t h e i n t r u s i o n o f a moderat ing m a t e r i a l such as water ) was l e s s than 0.95. F lood ing of t h e i n t e r i m s to rage area i s considered t o n o t be a c r e d i b l e event.


However, water was included in some of the criticality calculations to determine what effect it would have on keff if present. The most reactive hypothetical case analyzed assumed complete disintegration of fuel pins and duct, flooding of the CCC and suspension of the fuel pellets in water over a 36 inch height. This case led to a kef, greater than 1.00. However, in order for this to occur the following independent and highly unlikely events must happen.

flooding of the storage area failure of the ISC outer seal failure of the ISC inner seal failure of the CCC seal failure of the fuel pin cladding failure of the fuel assembly ducts optimization of the water/fuel geometry.

This combination of events far exceeds the double contingency principle generally used to assure criticality safety. these barriers would not result in loss of double contingency protection. any one of these events does not transpire the keff of the ISC and its contents will remain below 0.95 at the two sigma confidence level. requirements of DOE Order 5480.24 Section 7.a and 7.a.(2)(a), the double contingency principle, are met.

The loss of any single one of If

The

Contingencies related to mixing fuel assemblies and pin containers are addressed in Appendix C.

It can be concluded from this evaluation that unirradiated and irradiated FFTF fuel (29.32 wt% plutonium), stored in CCCs and ISCs, will remain safely subcritical during long term, interim storage.

3.0 FUEL AND CONTAINER DESCRIPTIONS Figure 1 illustrates the construction of the Driver Fuel Assemblies (DFAs) for the FFTF. The fuel pin specifications are listed in Table 1. Figure 2 illustrates the radial geometry of the CCC with Ident-69 pin containers in the six tubes surrounding the center tube. cover which allows insertion of a DFA into the center tube. The figure shows the CCC inside the small diameter cleaning vessel (SDCV). On the ISA, the CCC will reside in the Interim Storage Container (ISC). The ISC has an inner cavity, 150 inches long with a 21 inch diameter, to hold the CCC. itself consists of an inner stainless steel liner within a carbon steel shield

The grapple is located on the CCC

The ISC


of 32 inch diameter. A 0.75 inch gap exists between the liner and shield. The shield is enclosed by a concrete annulus with an outside diameter of 83 3/4 inches. Total ISC height i s 180 inches.

There are three high integrity mechanical seals blocking access of water from the outside into the CCC. The CCC lid contains one mechanical seal which functions once the lid is bolted on. After the CCC has been transferred into the ISC, the shielded closure is installed. The ISC closure contains redundant mechanical seals which function once its closure is bolted on.

4 . 0 ANALYSIS

4.1 Previous Analvses Previous analyses have addressed the storage of six fuel assemblies and Ident- 69 fuel pin containers in CCCs. This current report supplements the previous reports. CCC dimensions for the previous reports (Wilcox 1991, Erickson 1993) were from drawing H-4-66696.

All previous analyses assumed the center tube to be water filled.

The Ident-69 analysis (Wilcox 1991) determined the multiplication factor for the most reactive Ident-69 fuel pin loading in a CCC. arrangement of pins in an Ident-69 pin container is a fully flooded square array of 97 pins with a 0.4875 inch pitch. CCC containing six such Ident-69s is 0.8484 ? 0.0055 (1 sigma). The Wilcox analysis also addressed the reactivity effect of Ident-69 fuel pin breakage. This simulates the "hot cell rot" phenomenon. The results show that initially, as the fuel breaks up and mixes with the water, there is a small increase in reactivity. As more fuel pins break, the reactivity decreases. Wilcox concluded that the system will remain safely subcritical. Likewise, if the fuel pin breakage, within an Ident-69 pin container, is due to "hot cell rot," the pin container would be expected to retain its integrity and the system would remain safely subcritical.

The most reactive

The multiplication factor for a

The fuel assembly analysis (Erickson 1993) for six intact assemblies, concluded that 'the criticality criterion will not be exceeded and a criticality event is not credible during the normal fuel handling operations, nor during the accident conditions considered in this document.'

WHC-SD-FF-CSER.004, REV 1 Page 6

- I L 0.584 diameter

Fuel Pin - 1 1 -

0.726 Pitch

- 0.305 Wall

11.621

a ) Cross-sec t ion Through Fueled Region

F i s u r e 1: BASIC DESIGN FEATURES OF FFTF DRIVER FUEL ASSEMBLY

UHC-SO-FF-CSER-004, REV 1 Page 7

Table 1 :

FTR DRIVER FUEL ASSEMBLY NOMINAL DIMENSIONS AT 3OoC

Number o f p ins pe r assembly

Fuel p e l l e t end geometry

Fuel p e l l e t OD

P l a n a r smeared d e n s i t y

Fuel composi t ion

Cladding and duc t ma te r i a l

Cladding tube ID

C1 adding tube OD

Spacer system

Spacer w i r e d iameter

Spacer w i re p i t ch

Duct t ube inne r dimension

Duct wal l t h i ckness

Fuel p e l l e t s t a c k l eng th

I n s u l a t o r p e l l e t s t a c k l eng th

Axial r e f l e c t o r l eng th

Axial r e f l e c t o r ma te r i a l

Axial r e f l e c t o r geometry

217

d ished

0.494 c a (0.1945 i n . )

0.855 g/cm3

(U 7 PU) 0, .96

316 55

0.508 crn (0.200 i n . )

0.584 cm (0.230 i n . )

s p i r a l w i re wrap

0.142 cm (0.056 i n . )

30.48 cm (12. i n . )

11.011 cm (4.335 i n . )

0.3048 cm (0.120 i n . )

91.44 5 0.3175 cm (36 k 0.125 i n . )

2.032 cm (0 .8 i n . ) each end

14.478 cn (5.7 i n . ) each end

Inconel-500

cy1 i n d r i c a l rod , 0.4813 cx (0.1895 i n . ) OD

( d a t a from Erickson. 1993)

WHC-SD-FF-CSER-004. REV 1 Page 8

Fiqure 2: TOP VIEW OF CORE COMPONENT CONTAINER INSIDE OF SMALL DIAMETER CLEANING VESSEL (CALCULATIONS MODELLED CCC IN 53 CM DIA. CAVITY OF 2.1 M DIA. INTERIM STORAGE CASK)

WHC-SD-FF-CSER-'004 REV 1 Page 9

CCC's c o n t a i n i n g s i x FFTF f u e l assemblies o r s i x Ident-69 p i n c o n t a i n e r s a f f e c t e d by " h o t c e l l r o t " were analyzed and found t o be acceptab le f rom a n u c l e a r c r i t i c a l i t y p e r s p e c t i v e (Richard 1994). For any c r e d i b l e c o n f i g u r a t i o n keff w i l l remain f a r below 0.95.

4.2 Seven Fuel Assemblies i n a CCC An e v a l u a t i o n (Bunch, 1992) o f t h e maximum a l l o w a b l e keff f o r FFTF f a c i l i t i e s concluded t h a t a keff o f 0.95 prov ides an adequate s a f e t y margin i n t h e des ign o r m o d i f i c a t i o n o f f a c i l i t i e s f o r c lean ing , hand l ing and s t o r i n g f i s s i l e m a t e r i a l a t FFTF. The Monte Car lo c r i t i c a l i t y computer code, MONK6B (Smith, 1989), was used f o r t h e c a l c u l a t i o n s i n t h i s p resent s tudy . documents (Mack l in 1991, M i l l e r 1994) f o r MONKGB s p e c i f y t h a t a c a l c u l a t e d va lue o f 0.935 o r l e s s i s r e q u i r e d t o assure a kef, o f 0.95 o r l e s s , a l l o w i n g f o r b iases and a 2a u n c e r t a i n t y .

The v a l i d a t i o n

The CCC c o n s i s t s o f a r i n g o f s i x r a d i a l storage tubes around a c e n t e r s to rage tube F i g u r e 2. There are no s i g n i f i c a n t d i f f e r e n c e s between t h e dimensions o f drawing number H-4-72005, used f o r t h i s study, and drawing number H-4-66696, used f o r p r e v i o u s s t u d i e s . The c e n t r a l tube has t h e same diameter and a s l i g h t l y g r e a t e r w a l l t h i c k n e s s than t h e s i x r a d i a l tubes. For conservat ism and s i m p l e r modeling, t h e c e n t r a l tube i s assumed t o have t h e same dimensions as t h e s to rage tubes. assumption r e s u l t s i n reduced s t e e l mass f o r t h e c e n t e r tube and has a n e g l i b l e e f f e c t on t h e r e s u l t s . The CCC i s designed t o m a i n t a i n i t ' s p h y s i c a l i n t e g r i t y and w i l l n o t be adversely a f f e c t e d by ' h o t c e l l r o t ' . For a l l seven tubes o f t h e CCC t h e i n n e r diameter used i s 6.41 inches and t h e o u t e r diameter i s 6.65 inches. The t o t a l l e n g t h o f t h e CCC i s 145 inches . The 0.12 i n c h tube w a l l t h i c k n e s s assumed i s s l i g h t l y g r e a t e r than t h e a c t u a l w a l l t h i c k n e s s of 0.109 inch . However, t h e e f f e c t on t h e r e s u l t s o f t h i s a n a l y s i s due t o t h e d i f f e r e n c e i n w a l l t h i c k n e s s i s i n s i g n i f i c a n t . Two prev ious analyses (Wi lcox 1991, Er ickson 1993) addressed t h e r e a c t i v i t y e f f e c t due t o a change i n w a l l t h i c k n e s s . Both concluded t h a t t h e e f f e c t i s w i t h i n t h e s t a t i s t i c a l u n c e r t a i n t y o f t h e c a l c u l a t i o n s . a w a l l t h i c k n e s s change from 0.134 i n c h t o 0.109 i n c h .

Dimensions are from drawing number H-4-72005.

T h i s

From Wilcox, t h e kef, change was +0.0014 f o r


ISOTOPE

Pu-239

Pu-240

Pu-241

Pu-242

U-235

U-238

Am-241

0

MASS (9)

8421.38

1151.97

100.49

18.97

46.64

23274.00

41.86

4438.05

WHC-SO-FF-CSER-004 REV 1 Page 11

C a l c u l a t i o n s show t h a t a CCC c o n t a i n i n g seven moderated Ident-69 p i n c o n t a i n e r s w i t h o u t " h o t c e l l r o t " would exceed t h e 0.95 k e f f l i m i t ( s e c t i o n 5.2). A p rev ious a n a l y s i s (Richard 1994), shows t h a t s i x Ident-69 p i n c o n t a i n e r s can be s a f e l y s t o r e d i n a CCC. I S C p rec ludes hav ing a p i n c o n t a i n e r i n t h e center tube a t t h e I S A .

Design o f t h e s o l i d waste cask and

4.3 M u l t i D l e I S C Storaqe A f t e r t h e f i l l e d CCCs are p laced i n t o ISCs, t h e ISCs w i l l be s t o r e d on a concre te pad i n t h e 400 Area. Up t o 60 ISCs w i l l be s to red . The ISCs w i l l c o n t a i n f u e l assemblies o r Ident-69 p i n conta iners . The n e u t r o n i c i n t e r a c t i o n between ISCs has been analyzed. Each 20 i n c h diameter CCC r e s i d e s i n t h e 21 i n c h diameter h o l e i n t h e c e n t e r o f an I S C . An I S C has a nominal o u t e r d iameter o f 83 3/4 inches, i n c l u d i n g an 8 i n c h t h i c k i n n e r carbon s t e e l l i n e r surrounded by o r d i n a r y concrete. Most c a l c u l a t i o n s assumed t h e i n n e r s t e e l l i n e r t o be 5.4 inches t h i c k and t h e I S C o u t e r diameter t o be 85 inches. C a l c u l a t i o n s done w i t h 8 i n c h t h i c k carbon s t e e l and an I S C o u t e r d iameter as smal l as 80 inches gave t h e same r e s u l t s . S u b s t i t u t i o n o f carbon s t e e l w i t h s t a i n l e s s s t e e l has no e f f e c t on keff .

5.0 RESULTS

5.1 Hot C e l l Rot Table 3 shows t h e kef, o f seven DFAs s t o r e d i n a CCC w i t h i n an I S C f o r t h e d r y c o n d i t i o n . inc reases t o a maximum as t h e DFAs d i s i n t e g r a t e and t h e f u e l r e g i o n c o l l a p s e s t o t h e minimum 12.3 i n c h h e i g h t . However, even a t t h e minimum h e i g h t t h e c a l c u l a t e d kef, o f about 0.79 i s f a r below t h e acceptable l i m i t o f 0.935. The r e s u l t s f o r a l l cases i n t h i s t a b l e assume t h a t t h e d i s i n t e g r a t e d s t a i n l e s s s t e e l c l a d d i n g i n t h e f u e l r e g i o n i s homogeneously mixed w i t h t h e f u e l . The duc t i s i n t a c t f o r t h e 36.0 and 21.1 i n c h cases and d i s i n t e g r a t e d f o r t h e 12.3 i n c h case. When t h e duc t i s d i s i n t e g r a t e d , t h e r e s u l t i n g m a t e r i a l mix assumes t h e i n n e r diameter o f t h e CCC s to rage tube. The 21.1 i n c h h e i g h t i s t h e minimum fue l h e i g h t w i t h t h e duc t i n t a c t , and 12.3 inches i s t h e minimum f u e l h e i g h t w i t h t h e d u c t d i s i n t e g r a t e d .

The keff i s smal les t a t 36 inches when t h e DFAs are i n t a c t . It


Fuel Region H e i g h t ( inches)

S t a t i s t i c a l Case kef f U n c e r t a i n t y (+ Iu) Name

36.0

21.1

12.3

Table 4 shows d r y r e s u l t s w i t h t h e l e s s l i k e l y assumption t h a t t h e s t a i n l e s s s t e e l does n o t mix w i t h t h e f u e l . The e n t i r e assembly i n c l u d i n g t h e d u c t i s assumed t o have d i s i n t e g r a t e d . Comparison o f t h e 12.3 i n c h h e i g h t cases from Tables 3 and 4 shows t h e e f f e c t o f separa t ing o u t t h e s t a i n l e s s s t e e l . A t t h e minimum h e i g h t o f 7.2 inches t h e c a l c u l a t e d kef, o f t h e CCC i s a maximum o f 0.9294. T h i s i s s t i l l below t h e 0.935 l i m i t .

0.4352 0.0015 cc7df36d

0.5950 0.0019 cc7df21d

0.7862 0.0024 cc7df 12d

For t a b l e s 3 and 4, r e f l e c t i o n i s p rov ided by t h e concre te and s t e e l o f t h e I S C , and t h e f u e l i s i n powder form. For these d r y cases, whether f u e l i s modeled as powder o r p e l l e t s has an i n s i g n i f i c a n t a f f e c t on r e a c t i v i t y .

Tab le 4. Seven Dry Assemblies w i t h Fuel and S t a i n l e s s S t e e l Separated

Fuel Region H e i g h t ( inches)

12.3

7.2

S t a t i s t i c a l Case kef U n c e r t a i n t y (+ lu) Name

0.7536 0.0023 ccc7dfns l2 ,

0.9294 0.0025 ccc7dfns7

Since s t a i n l e s s s t e e l i s a neut ron absorber i t might be expected t h a t kef, would inc rease when i t i s removed from t h e f u e l . r e s u l t s f o r t h e 12.3 i n c h h e i g h t f rom Tables 3 and 4, shows t h a t removal o f t h e s t a i n l e s s s t e e l r e s u l t s i n a r e d u c t i o n i n keff f o r t h e d r y c o n d i t i o n . T h i s can be exp la ined as f o l l o w s . The f i s s i o n s i n t h e MOX f u e l occur p r i m a r i l y i n t h e f a s t neut ron energy r e g i o n (E,>100 keV). However, a s i g n i f i c a n t f r a c t i o n (-30%) o f t h e f i s s i o n s i n Pu-239 occur i n t h e 0.4 eV t o 100 keV neut ron energy range. occupied by t h e s t a i n l e s s s t e e l o f t h e duc t and c ladd ing . s t e e l i s removed, fewer neut ron s c a t t e r i n g i n t e r a c t i o n s occur r e s u l t i n g i n fewer neut rons i n t h e 0.4 eV t o 100 keV energy range. The r e s u l t i s a 24%

However, comparison o f

For t h e 12.3 i n c h case r e p o r t e d i n Table 3, 42% o f t h e volume i s When t h e s t a i n l e s s


Homogenized Fuel Region S t a t i s t i c a l

H e i g h t ( inches) kef , U n c e r t a i n t y (2 la)

36.0 0.8201 0.0028

31.5 0.8194 0.0029

26.0 0.8144 0.0030

21.1 0.7994 0.0028

r e d u c t i o n i n t h e number o f f i s s i o n s o c c u r r i n g i n Pu-239 i n t h e 0.4 eV t o 100 keV energy range. f i s s i o n s r e s u l t s i n a n e t r e d u c t i o n i n t o t a l f i s s i o n s by about 5.0%. Therefore, kef, goes down. neut ron leakage f r a c t i o n f o r t h e f i s s i l e medium.

Th is , a long w i t h a 2% decrease i n t h e number o f f a s t

The reduced s c a t t e r i n g a l s o y i e l d s a h i g h e r

Case Name

ccc7dfas

cc7df31 f

cc7df26 f

cc7df21 f

Under f u l l y f l o o d e d CCC c o n d i t i o n s , as a l l t h e f u e l p i n s c o l l a p s e and d i s i n t e g r a t e i n t o a homogeneous m i x t u r e o f f u e l , c lad , and water w i t h i n t h e i n t a c t d u c t t h e h i g h e s t va lue o f occurs f o r t h e 36 i n c h f u e l h e i g h t , g i v i n g t h e 0.8201 va lue shown i n Table 5. w i t h i n t h e duc t , keff decreases. homogeneously mixed w i t h t h e f u e l and water.

As t h e f u e l p i n s d i s i n t e g r a t e and c o l l a p s e The s t a i n l e s s s t e e l o f t h e c l a d d i n g i s

Table 5 bounds t h e case o f water

i n s i d e t h e I S C w i t h t h e CCC d r y and t h e duc t i n t a c t . No apprec iab le amount o f f u e l would be expected t o come out o f t h e duc t w i t h t h e duc t i n t a c t . For i n t a c t p i n s (36 i n c h f u e l l e n g t h ) , kef, i s 0.7836.

The f u l l y f looded c o n d i t i o n assumes complete f l o o d i n g i n s i d e t h e I S C , i n c l u d i n g i n s i d e and o u t s i d e t h e CCC. F u l l f l o o d i n g i s a h i g h l y undermoderated c o n d i t i o n . Any decrease i n water d e n s i t y o r volume would reduce k,,,.

Since t h e f u e l p i n c l a d d i n g (0.015 i n c h ) i s much t h i n n e r than t h e d u c t (0.12 i n c h ) , i t w i l l d i s i n t e g r a t e l o n g b e f o r e t h e duc t i s a f f e c t e d . i f ever , t h e d u c t f a l l s apar t , t h e f u e l p i n d e b r i s would have s e t t l e d so t h a t t h e f u e l r e g i o n h e i g h t would be much l e s s than t h e o r i g i n a l 36 inches.

Before,


Fuel Region Height (inches)

36.0

27.0

18.9

13.0

Statistical Case keff Uncertainty (+lo) Name

1.1347 0.0028 spf7df36

1.0876 0.0030 spf7df27

1.0354 0.0030 spf7df 19

0.9695 0.0030 spf7df13


must fail. And finally, the ISC must tip over. These are all independent and unlikely events. criticality. In addition, the ISC seals will be tested prior to any movement to insure seal integrity. Consequently, criticality as a result of an ISC tipping over at the ISA is not credible. consequence of dry ISCs tipping over at the ISA due to an industrial accident involving the mobile crane.

More than two contingencies must occur to achieve

There would be no criticality safety

The possibiity exists for some fuel pins within the intact DFA duct to disintegrate while the remainder remain intact. thicker than the cladding it would be reasonable to expect a mixture of intact pins and disintegrated pins only while the duct is still intact. With the duct still intact reactivity increases as the pins disintegrate for the fully flooded condition. pieces mix homogeneously in the water, the moderation improves and therefore reactivity continues to go up until all of the pins disintegrate. Since the duct is much thicker than the pin cladding, the pins will be completely disintegrated before the duct fails. homogenous mixture of debris and water within the CCC storage tubes, the reactivity continues to increase. in powder or pellet form (Table 5 and Table 6, respectively) and water is more conservative than the inclusion of some intact pins.

Because the duct is so much

As the undermoderated intact pins fall apart and the

As duct failure occurs and assuming

The homogeneous mix of disintegrated fuel

Figure 3 shows plots of results for CCCs with fuel assemblies for the various geometric configurations analyzed. are those in which the CCC is flooded, 'hot cell rot' and complete duct fai 1 ure has occurred.

The only cases where kef, exceeds 0.935

If the fuel form is assumed to be powder rather than pellets, the resulting keff is less for any given height. For example, for the duct disintegrated case with a fuel region height of 36" and full water moderation kef, is 1.0595 when the fuel is in powder form and 1.1347 when the fuel is in pellet form.


Fuel Region Length ( inches)

There fore , f o r conservat ism, t h e d i s i n t e g r a t e d f u e l i s assumed t o be i n t h e p e l l e t form when t h e DFAs are comple te ly d i s i n t e g r a t e d .

S t a t i s t i c a l keff U n c e r t a i n t y (+ Iu)

E v e n t u a l l y t h e ISCs w i l l be t r a n s p o r t e d away from t h e 400 Area. r o t " may have a f f e c t e d some f u e l p i n s by t h a t t ime. remain i n t a c t . t r a n s p o r t a t i o n , t h e f u e l r e g i o n o f t h e " h o t c e l l r o t " a f f e c t e d p i n s may extend beyond t h e normal 36 i n c h l e n g t h . Since t h e 36 i n c h f u e l r e g i o n l e n g t h i s an undermoderated c o n d i t i o n , any inc rease w i l l r e s u l t i n improved moderat ion and h i g h e r k,,,'s.Table 7 shows t h e a f f e c t o f i n c r e a s i n g t h e f u e l r e g i o n from 36 inches t o 140 inches. The f u e l i s modeled as f u e l p e l l e t s i z e spheres, t h e d u c t i s i n t a c t and f l o o d i n g i s assumed.

"Hot c e l l The assembly duc ts w i l l

I f t h e I S C were t o somehow f a l l over on to i t s s i d e d u r i n g

0.8418 0.8521

Tab le 7. ked< f o r H o r i z o n t a l ISC ( I n t a c t Duct)

0.0028 ccc7hexsp 0.0028 ccc7hexsp05

I 70 0.8714 0.0028 ccc7hexsp07 120 0.8758 0.0029 ccc7hexspl2 140 0.8576 0.0027 ccc7hexspl4

~ ~~~

As t h e f u e l r e g i o n i s extended keff r i s e s t o a maximum o f 0.8758 a t 120 inches

and then drops o f f . The r e s u l t s c l e a r l y show t h a t w i t h duc ts i n t a c t , " h o t

c e l l r o t " a f f e c t e d f u e l p i n s , f l o o d i n g and t i p p i n g over t h e I S C remains

s u b c r i t i c a l .

5.2 Seven Ident-69s

A s e t o f c a l c u l a t i o n s were done t o determine t h e maximum number o f Ident-69s

t h a t a CCC i n s i d e an I S C can c o n t a i n . The c a l c u l a t e d k e f f ' s f o r s i x o r seven

I d e n t 69s are shown i n t a b l e 8.


Number o f Ident-69s (97 I n t a c t P ins Each)

6

7

kef f S t a t i s t i c a l U n c e r t a i n t y Case (+ 1 4 Name

0.8651 0.0079 ccc61&9wa 0.9927 0.0031 ccc7id69wa

S i x Ident-69s conta ined i n a CCC have been shown t o be acceptable f rom a n u c l e a r c r i t i c a l i t y p e r s p e c t i v e (Richard 1994). Examinat ion o f Table 8 shows t h a t a CCC c o n t a i n i n g seven Ident-69s has a kef, o f 0.9927. i s r e s t r i c t e d t o c o n t a i n no more than 6 Ident-69s. A d d i t i o n a l l y , an Ident -69 i s n o t a l lowed i n t h e c e n t e r tube o f a CCC.

addresses m i x i n g f u e l assemblies and p i n conta iners .

Therefore, a CCC

Appendix C and Sect ion 6.0

The seven assembly (d ry , s e c t i o n 5.1) case bounds t h e e r r o r o f a f u e l assembly

o r p i n c o n t a i n e r i n t h e c e n t e r tube o f a CCC c o n t a i n i n g s i x Ident-69s, f o r t h e

d r y c o n d i t i o n .

5.3 M u l t i D l e I S C Storase

Seven f u e l assemblies, s i x Ident-69 p i n c o n t a i n e r s o r a mix o f two f u e l

assemblies and f i v e p i n c o n t a i n e r s (Appendix C) w i l l be p laced i n t o a CCC

which, i n t u r n , w i l l be s t o r e d i n s i d e an I S C . Up t o 60 ISCs w i l l be s t o r e d on

a concre te pad a t t h e I n t e r i m Storage Area ( I S A ) o f t h e 400 Area. The MONK6

Monte C a r l o code was used t o determine t h e n e u t r o n i c i n t e r a c t i o n between t h e

s t o r e d ISCs. For a l l cases, each CCC was assumed t o c o n t a i n seven i n t a c t and

f u l l y f looded 4.1 DFAs w i t h t h e f u l l 36 i n c h f u e l r e g i o n h e i g h t . Any growth

i n p i n h e i g h t o r diameter due t o i r r a d i a t i o n w i l l have a n e g l i g i b l e e f f e c t on

kef,. are ad jacent . Resu l ts are shown i n Table 9. The f i r s t case i s f o r a s i n g l e

I S C surrounded by 6 inches o f water r e f l e c t i o n . The n e x t two cases are

i n f i n i t e a r r a y s of ISCs. For t h e f i r s t i n f i n i t e a r r a y case, t h e space between

t h e ISCs i s empty, f o r t h e second case t h e space between ISCs i s water f i l l e d .

The I S C c a v i t y c o n t a i n i n g t h e CCC i s a l s o f u l l y f l o o d e d and t h e ISCs


Number o f ISCs

1

Infinite Array

Infinite Array

There is a small increase in keff (less than 1 sigma) when the number of ISCs

increase from one to infinity with or without moderation outside the ISC. Full

moderation outside the ISCs requires the storage pad to be completely flooded.

This is considered to not be a credible event. Without flooding keff is

slightly less for the infinite array. Even with flooding, keff is far less

than 0.95 for assemblies or pin containers. Since the cases shown include

flooding inside the CCC and ISC, the kef, for the more realistic completely

internally dry case will be far less. The occurrence of "hot cell rot" will

Moderation Statistical Case Outside ISC k,,, 'Uncertainty ( t lu ) Names

Water 0.8201 0.0028 ccc7dfas

None 0.8208 0.0029 infiscd

Water 0.8219 0.0028 infiscw

have no affect on ISC interaction. It is clear that any number of ISCs can be

safely stored on the 400 Area storage pad without any spacing restriction.

There are no fire fighting restrictions for ISA, and the fire fighting

category should be A .

5.4 MultiDle CCCs

Table 10 lists the keff for up to 64 dry adjacent CCCs.

intact Type A assemblies.

to 217 Type A pins per pin container.

when fissionable material is securely packaged within a container of high

integrity, the geometry restrictions imposed by the container may be taken

into account. Both the CCC and ISC are containers of high integrity,

therefore moderator exclusion can be assumed to determine the critical number.

For a single dry unreflected CCC, keff i s 0.3096.

Each CCC contains 7

These results also bound dry pin containers with up

Nuclear Safety Limit 20.3.2 states that

For an 8 x 8 array of


Number o f cccs k,,,

1 0.3096

2 0.3491

64 0.9672

unreflected dry CCCs keff is 0.9672. A critical number is the number of CCCs

necessary to achieve criticality. Nuclear Safety Limit 20.3.2 requires that a

batch shall not exceed 0.45 of a critical quantity. It is clear that a single

dry CCC containing seven fuel assemblies or six pin containers is far less

than 0.45 of a critical quantity. In addition, a single dry CCC is less than

0.33 of a critical quantity, which justifies not having a Criticality Alarm

System for the ISA. 'Hot cell rot' will not occur in CCCs prior to insertion

into the ISC and storage on the storage pad. The occurrence of 'hot cell rot'

in ISCs was addressed in Section 5.3.

S t a t i s t i c a l Case Uncertainty (* lu) Name

0.0013 1 cccw7df ad

0.0013 2cccw7dfad

0.0030 64cccw7df ad

As shown in Section 5.3, an infinite array of ISCs is far below critical.

Therefore, it is not credible to have a critical number of ISCs as shown in

Table 9.

+ Fuel Pellets,Flooded *< Duct Intact,Flooded * Dry,MOX and Stainless Steel Mix -+- Dry,Mox

1.20

1.10

1 .oo

0.90

0.80

0.70

0.60

0.50

0.49

5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00


6.0 CONCLUSIONS

The results of this study show that the plan for storage o f seven irradiated FFTF driver fuel assemblies or six pin containers, with no pin container in the center tube, in ISCs is acceptable from a criticality safety perspective. Mixing up to seven fuel assemblies and pin containers, with no more than five pin containers and no pin container in the center tube, is also acceptable (Appendix C). A criticality alarm system is not required at the ISA.

The kef, of the most reactive credible configuration of a single CCC or ISC analyzed (without allowing for flooding) is less than 0.8. For intact fuel assemblies keff is 0.4352 for the dry case and 0.8201 for the flooded case.

The flooded six pin container case with intact pins has a kef, of 0.8651. dry pin container case (intact pins) and the dry case with a mixture of pin containers and assemblies is bounded by the dry fuel assembly (intact pins) case. A flooded CCC with five pin containers and two fuel assemblies, with intact pins, has a keff of 0.9188 (Appendix C).

The

Complete disintegration of the fuel pins, within the duct, and flooding of the CCC are both considered not credible. However, even if the pins disintegrated and the system is flooded, kef' would not exceed 0.8418. pin containers and fuel assemblies, with the same incredible conditions, would have a kef, no greater than 0.9258 (Appendix C). container case with disintegrated pins would remain safely subcritical.

A CCC with a mix of

The flooded six pin

There is negligible neutronic interaction between ISCs containing CCCs. Therefore, storage of any number of ISCs on the 400 Area storage pad without spacing is acceptable from a criticality safety perspective.

If an ISC is tipped onto its side during transportation and "hot cell rot" and flooding occurs, kef, for assemblies with intact ducts will not exceed 0.8758. Appendix C addresses tipping of an ICs containing a mix of fuel assemblies and pin containers. tipover is not credible.

It concludes that an increase in kef, resulting from an ISC

The only situations in which keff was found to exceed 0.935, for seven fuel assemblies or six pin containers in an ISC, required the following independent and highly unlikely conditions:

Flooding of the storage area - The ISCs will be stored on a concrete pad above the flood plain and will have environmental covers for protection from rain and snow.


Failure of the ISC outer seal - The ISC outer seal would prevent water from reaching the ISC inner seal.

Failure of the ISC inner seal - the ISC inner seal would prevent water from reaching the CCC.

Failure of the CCC seal - The CCC seal would keep water out of the storage tubes.

Failure of the fuel pin cladding - requires the occurrence of 'hot cell rot. '

Failure of the fuel assembly ducts - The fuel assembly ducts are almost an order of magnitude thicker than the fuel pin cladding. been no observed case o f duct failure or degradation due to "hot cell rot" and is not expected to occur.

There has

Optimization of the water/fuel geometry - A critical configuration the fuel material would have to remain optimized in water without duct integrity.

This combination of events far exceeds the double-contingency principle generally used to assure nuclear criticality safety. seven conditions is not satisfied, the kef, of the ISC and its contents and an array of ISCs will remain below 0.95 allowing for biases and a two sigma confidence level. Finally, the concurrent occurrence of all these events is not credible. assemblies are discussed in Appendix C. The fire fighting category is A for the ISA.

If any one of these

Contingencies related to mixing pin containers and fuel

7.0 VALIDATION

In order to verify the accuracy of the methods used in this analysis, comparison calculations were made with previous criticality analyses done for the CCC, i.e. the original Wilcox (1989) analysis and an updated Erickson (1993) analysis. and assumed intact DFAs in the CCC (drawing H-4-66696); i.e., no occurrence of 'hot cell rot' of the fuel assemblies was considered.

Both of these earlier analyses used the MCNP computer code


Tab le 11. Comparison o f O r i g i n a l MCNP and MONK6

Computer S t a t i s t i c a l Code kef, U n c e r t a i n t y (tlo)

I

MCNP . . o r u l a n a l v s i s ) 0.657 n o t o i v e n

MONK6 0.6451 0.0027

The f u e l rods i n t h e DFAs f o r t h e o r i g i n a l Wi lcox a n a l y s i s were modeled as a homogenized c y l i n d e r p r e s e r v i n g t h e f u e l element volumes w i t h i n t h e s i x s to rage tubes o f t h e CCC.

s i t u a t i o n s . The CCC was f u l l y f l o o d e d w i t h 100% water d e n s i t y i n t h e vo ids and steam around t h e f u e l p i n s i n s i d e t h e DFA. Atom d e n s i t i e s f o r t h e m i x t u r e o f f u e l and water were taken from t h e o r i g i n a l a n a l y s i s and i n s e r t e d i n t o t h e MONK6 model o f t h e CCC used f o r t h e c u r r e n t a n a l y s i s . The r e s u l t s a re shown i n Table 11.

A v a r i e t y o f c a l c u l a t i o n s was done f o r v a r i o u s A comparison c a l c u l a t i o n was made f o r a f u l l y water f l o o d e d case.

The updated Er ickson (1993) a n a l y s i s e x p l i c i t l y modeled t h e f u e l p i n s w i t h i n t h e hexagonal DFA duc t . For comparison t o t h e MONK6 c a l c u l a t i o n s a f u l l y f l o o d e d case was used. A l l voided r e g i o n s had f u l l water d e n s i t y i n c l u d i n g t h e vo ids between t h e f u e l p i n s w i t h i n t h e duc t . t h e Er ickson MCNP c a l c u l a t i o n used e x p l i c i t l y modeled f u e l p i n s w h i l e t h e MONK6 c a l c u l a t i o n used homogenized atom d e n s i t i e s f o r t h e f u e l p i n s and water w i t h i n t h e duc t .

The f u e l enrichment used was e q u i v a l e n t t o a 4.1 DFA.

The o n l y d i f f e r e n c e between t h e c a l c u l a t i o n s i s t h a t

Table 12 p resents t h e r e s u l t s .


Computer Code

MCNP

S t a t i s t i c a l Case kef+ U n c e r t a i n t y (+ lo) Name

0.7034 0.0040

MONK6

The r e s u l t s o f these comparisons demonstrate t h e cons is tency between t h e t h r e e

independent analyses.

0.7084 0.0026 ho t ro t50h2

D i r e c t comparisons o f MONK6A c a l c u l a t i o n s aga ins t c r i t i c a l exper iments i n v o l v i n g mixed ox ide f u e l p i n s a k i n t o t h e FFTF f u e l have been r e p o r t e d by Rogers (1991) i n a Safe ty Ana lys is f o r Packaging (SARP) f o r t h e T-3 cask (which w i l l accomodate an Ident-69 c o n t a i n e r ) . Eva lua t ions o f t h e ca lcu la ted /exper imenta l b i a s and combined u n c e r t a i n t i e s i n d i c a t e t h a t system c a l c u l a t i o n k - e f f e c t i v e values l i m i t e d t o 0.932 o r l e s s are acceptable, t h a t t h e t r u e values w i l l n o t exceed 0.95 w i t h 95% conf idence. M i l l e r (1994) demonstrated t h e equivalence o f MONK6B t o MONK6A by v i r t u e o f t h e c ross- s e c t i o n l i b r a r y o f t h e two vers ions being i d e n t i c a l .


8.0 REFERENCES

M i l l e r , E. M., 1994, MONK6B Pu Va l i da t i on , WHC-SD-SQA-CSWD-20019 Rev. 0,

EDT 157930, Westinghouse Hanford Company.

Richard, R.F., A p r i l 19, 1994, C r i t i c a l i t y Eva lua t i on f o r Long Term

Storage o f FFTF Fuel i n I n t e r i m Storage Casks, WHC-SD-FF-CSER-003 Rev

0, EDT 157477, Westinghouse Hanford Company.

Er ickson, D. G. , June 17, 1993, C r i t i c a l i t y Safety Eva lua t i on Report o f

Fuel Assemblies i n Core Component Containers, WHC-SD-FF-CSER-002. Rev.

0, EDT 109191, Westinghouse Hanford Company.

Wal tar , A. E., 1993, "T ransmi t ta l o f White Paper on Long Term ( I n t e r i m )

Storage o f Spent FFTF Fuel," January 29, 1993.

I n t e r n a l Memo, W . L. Bunch, L. L. Car te r and R. J. Mor ford t o

J. W. Daughtry, "Maximum Al lowable keff f o r FFTF F a c i l i t i e s , " dated

June 23, 1992.

Wilcox, A.D., and Schwinkendorf, K. N., November 14, 1991, " C r i t i c a l i t y

Safety Eva lua t i on o f I den t 69s i n Core Component Container," WHC-SD-

FV792-DA-004 Rev. 0, EDT 109172, Westinghouse Hanford Company.


L. L. Mackl in and E . M. M i l l e r , November 1, 1991, "MONK6A Pu V a l i d a t i o n "

WHC-SD-SQA-CSWD-20015 Rev. 0, Westinghouse Hanford Company.

Wilcox, A. D., A p r i l 20,1989, C r i t i c a l i t y Ana lys i s f o r t h e SWTP,

WHC-SD-FV792-DA-00003, Rev. 0, EDT 466115, Westinghouse Hanford Company.

Smith, N. R., MONK6 User Guide, ANSWERS (MONK6) 1 AEEW R2195, issued

November 1, 1989.

Rogers, C. A., March 18, 1992, "Chapter 6 o f t h e T-3 Cask Safety

Ana lys i s Report f o r Packaging (SARP", WHC-SD-SQA-CSA-20333

WHC-SD-FF-CSER-004 REV 1 P a g e 27

APPENDIX A Sample MONK6B I n p u t F i l e


0.00001089 0.03198 0.0002603 0.0002117 0.009296 0.002756 0.001884 0.00003362 0.02916

0.00155 0.00126 0.05536 0.01641 0.01122 0.0002003

0.083491 0.003921

* A MONK6A model of a Core Component Cask (CCC) within an Interim * Storage Container (ISC). The ISC is a cylindrical concrete * container with an annulus for the CCC; the diameter is 85 inches * and the length is 180 inches. The annulus has a carbon steel * liner and carbon steel end pieces. Dimensions of the annulus * are 21 inches in diameter and 150 inches in length. This CCC * contains 7 DFAs. * Fully flooded 7 radial tubes. Fuel region height 91.44 cm. 43.60 percent water density * in fuel region, 100% in voids. Duct intact FISSION * Number of Material Number of Nuclides

5 21 NUCNAMES * Keyword Nuclide Concentration(number density) * Fuel and stainless steel homogeneous mix CONC PU239 0.002210

*

PU240 0.0003011 PU241 0.00002615 PU242 0.000004915 U235 0.00001245 U238 0.006134 AM241 0 MN MO FE CR NI C HINH20

* Stainless steel CONC MN

MO FE CR NI C

* Carbon steel CONC FE

C


* Concrete CONC

* Water CONC

* * CM *

H 0 SI FE NA23 C CA MG AL27

HINHLO 0

0.014868 0.041519 0.006037 0.0001968 0.000304 0.003814 0.01 1588 0.000587 0.000735

0.06689 0.03344

* The f o l l o w i n g i n p u t descr ibes t h e geometry NEST 4 * T h i s n e s t decr ibes t h e I n t e r i m Storage Cask ( I S C ) . * T h i s i s t h e i n n e r r e a i o n t h a t ho lds t h e Core Comoonent Conta iner ( C C C ) . 1 ZROD O R I G I N 0 0 38.11) P2 27.00 381.00 * T h i s i s t h e carbon s t e e l l i n e r 2 ZROD 3 40.64 457.20 * T h i s i s t h e concre te 3 ZROD 4 107.95 457.20 * T h i s i s o u t s i d e t h e I S C 4 ZROD 5 123.20 472.45 * t h e f o l l o w i n g c l u s t e r descr ibe t h e CCC w i t h i n t h e I S C CLUSTER 30 * s t a i n l e s s s t e e l i n tubes below f u e l r e g i o n 1 ZROD O R I G I N 0 0 38.10 P3 2 ZROD O R I G I N 0 16.94 38.10 P4 3 ZROD O R I G I N 14.6705 4 ZROD ORIGIN 14.6705 5 ZROD ORIGIN 0 6 ZROD ORIGIN -14.6705 7 ZROD ORIGIN -14.6705 * * f u e l r e g i o n i n t h e 7 tubes 8 ZROD O R I G I N 0 9 ZROD O R I G I N 0 10 ZROD ORIGIN 14.6705 11 ZROD ORIGIN 4.6705 12 ZROD O R I G I N 0 13 ZROD O R I G I N - 4.6705 14 ZROD O R I G I N - 4.6705 *

8.47 -8.47

-16.94 -8.47

8.47

0 16.94 8.47

-8.47 -16.94

-8.47 8.47

38.10 P5 38.10 P6 38.10 P7 38.10 P8 38.10 P9

98.274 P10 98.274 P11 98.274 P12 98.274 P13 98.274 P14 98.274 P15 98.274 PI6

8.45 8.45 8.45 8.45 8.45 8.45 8.45

8.45 8.45 8.45 8.45 8.45 8.45 8.45

60.174 60.174 60.174 60.174 60.174 60.174 60.174

91.44 91.44 91.44 91.44 91.44 91.44 91.44


* stainless steel i n the tubes above fuel region 15 ZROD ORIGIN 0 0 189.714 P17 16 ZROD ORIGIN 0 16.94 189.714 P18 17 ZROD ORIGIN 14.6705 8.47 189.714 P19 18 ZROD ORIGIN 14.6705 -8.47 189.714 P20 19 ZROD ORIGIN 0 -16.94 189.714 P21 20 ZROD ORIGIN -14.6705 -8.47 189.714 P22 21 ZROD ORIGIN -14.6705 8.47 189.714 P23 * * water in the 7 tubes above the stainless steel 22 ZROD O R I G I N 0 0 263.784 P24 23 ZROD O R I G I N 0 16.94 263.784 P25 24 ZROD O R I G I N 14.6705 8.47 263.784 P26 25 ZROD O R I G I N 14.6705 -8.47 263.784 P27 26 ZROD O R I G I N 0 -16.94 263.784 P28 27 ZROD O R I G I N -14.6705 -8.47 263.784 P29 28 ZROD O R I G I N -14.6705 8.47 263.784 P30 * * stainless steel cap on t o p 29 ZROD ORIGIN 0 0 393.70 2

* water surrounding the CCC 30 ZROD O R I G I N 0 0 38.10 5

*

* * * Darts 3 throuqh 9: stainless steel below fuel NEST 2 1 ZROD O R I G I N 0 2 ZROD O R I G I N 0 NEST 2 1 ZROD ORIGIN 0 2 ZROD ORIGIN 0 NEST 2 1 ZROD O R I G I N 14.6705 2 ZROD O R I G I N 14.6705 NEST 2 1 ZROD O R I G I N 14.6705 2 ZROD O R I G I N 14.6705 NEST 2 1 ZROD O R I G I N 0 2 ZROD O R I G I N 0 NEST 2 1 ZROD ORIGIN - 2 ZROD ORIGIN - NEST 2 1 ZROD O R I G I N - 2 ZROD O R I G I N - *

4.6705 4.6705

4.6705 4.6705

0 38.10 BH2 0 38.10 2

16.94 38.10 BH2 16.94 38.10 2

8.47 38.10 BH2 8.47 38.10 2

-8.47 38.10 BH2 -8.47 38.10 2

-16.94 38.10 BH2 -16.94 38.10 2

-8.47 38.10 BH2 -8.47 38.10 2

8.47 38.10 8H2 8.47 38.10 2

8.45 8.45 8.45 8.45 8.45 8.45 8.45

8.45 8.45 8.45 8.45 8.45 8.45 8.45

25.50

27.00

8.14 8.45

8.14 8.45

8.14 8.45

8.14 8.45

8.14 8.45

8.14 8.45

8.14 8.45

74.07 74.07 74.07 74.07 74.07 74.07 74.07

129.916 129.916 129.916 129.916 129.916 129.916 129.916

12.70

381.00

60.174 60.174

60.174 60.174

60.174 60.174

60.174 60.174

60.174 60.174

60.174 60.174

60.174 60.174


* Dar ts 10 th roush 16: f u e l r e g i o n NEST 2 1 ZROD O R I G I N 2 ZROD O R I G I N N E S T 2 1 ZROD O R I G I N 2 ZROD O R I G I N N E S T 2 1 ZROD O R I G I N 2 ZROD O R I G I N N E S T 2 1 ZROD O R I G I N 2 ZROD O R I G I N N E S T 2 1 ZROD O R I G I N 2 ZROD O R I G I N N E S T 2 1 ZROD O R I G I N 2 ZROD O R I G I N N E S T 2 1 ZROD O R I G I N 2 ZROD O R I G I N *

0 0

0 0

14.6705 14.6705

14.6705 14.6705

0 0

-14.6705 -14.6705

-14.6705 -14.6705

0 0

16.94 16.94

8.47 8.47

-8.47 -8.47

-16.94 -16.94

-8.47 -8.47

8.47 8.47

98.274 BH1 8.14 98.274 2 8.45

98.274 BH1 8.14 98.274 2 8.45

98.274 BH1 8.14 98.274 2 8.45

98.274 BH1 8.14 98.274 2 8.45

98.274 BH1 8.14 98.274 2 8.45

98.274 BH1 8.14 98.274 2 8.45

98.274 8H1 8.14 98.274 2 8.45

* Dar ts 17 throuah 23: s t a i n l e s s steel above f u e l N E ~ T 2 1 ZROD O R I G I N 0 2 ZROD O R I G I N 0 N E S T 2 1 ZROD O R I G I N 0 2 ZROD O R I G I N 0 N E S T 2 1 ZROD O R I G I N 14.6705 2 ZROD O R I G I N 14.6705 N E S T 2 1 ZROD O R I G I N 14.6705 2 ZROD O R I G I N 14.6705 N E S T 2 1 ZROO O R I G I N 2 ZROD O R I G I N N E S T 2 1 ZROD O R I G I N - 2 ZROD O R I G I N - N E S T 2 1 ZROD O R I G I N - 2 ZROD O R I G I N - *

0 0

4.6705 4.6705

4.6705 4.6705

0 0

16.94 16.94

8.47 8.47

-8.47 -8.47

-16.94 -16.94

-8.47 -8.47

8.47 8.47

189.714 BH2 8.14 189.714 2 8.45

189.714 BH2 8.14 189.714 2 8.45

189.714 BH2 8.14 189.714 2 8.45

189.714 BH2 8.14 189.714 2 8.45

189.714 BH2 8.14 189.714 2 8.45

189.714 BH2 8.14 189.714 2 8.45

189.714 BH2 8.14 189.714 2 8.45

91.44 91.44

91.44 91.44

91.44 91.44

91.44 91.44

91.44 91.44

91.44 91.44

91.44 91.44

74.07 74.07

74.07 74.07

74.07 74.07

74.07 74.07

74.07 74.07

74.07 74.07

74.07 74.07


* p a r t s 24 th rough 30: water above D F A s i n t ubes NEST 2 1 ZROD O R I G I N 0 0 263.784 5 8.14 129.916 2 ZROD O R I G I N 0 0 263.784 2 8.45 129.916 NEST 2 1 ZROD O R I G I N 0 16.94 263.784 5 8.14 129.916 2 ZROD O R I G I N 0 16.94 263.784 2 8.45 129.916 NEST 2 1 ZROD O R I G I N 14.6705 8.47 263.784 5 8.14 129.916 2 ZROD O R I G I N 14.6705 8.47 263.784 2 8.45 129.916 NEST 2 1 ZROD O R I G I N 14.6705 -8.47 263.784 5 8.14 129.916 2 ZROD O R I G I N 14.6705 -8.47 263.784 2 8.45 129.916 NEST 2 1 ZROD O R I G I N 0 2 ZROD O R I G I N 0 NEST 2 1 ZROD O R I G I N -14.6705 2 ZROD O R I G I N -14.6705

1 ZROD O R I G I N -14.6705 2 ZROD O R I G I N -14.6705

NEST 2

* * f u e l r eg ion hole * hole type T R I A N G L E * l a t t i c e p i t c h

4.0 * duc t dimensions WRAP * number o f t ubes * on s i d e

2 * mate r i a l i n s i d e * t ube

* duc t ma te r i a l 1

2

-16.94 263.784 5 8.14 129.916 -16.94 263.784 2 8.45 129.916

-8.47 263.784 5 8.14 129.916 -8.47 263.784 2 8.45 129.916

8.47 263.784 5 8.14 129.916 8.47 263.784 2 8.45 129.916

i npu t number of m a t e r i a l s

3 i nne r r a d i u s

1 .8

mate r i a l numbers 1 2 5

o u t e r r a d i u s 1.9

c e n t e r t o inne r duc t 5.50545

t ube ma te r i a l ma te r i a l

1 1 r e s t o f space

5

c e n t e r t o o u t e r duc t 5.81025

i n t e r s t i t u a l

* end o f f u e l r eg ion inpu t

* s t a i n l e s s s t e e l ho le inpu t * hole type T R I A N G L E 2 * l a t t i c e p i t c h

4.0 * duc t dimensions

* *

number of m a t e r i a l s

i n n e r r a d i u s 1.8

mate r i a l numbers 2 5

o u t e r r a d i u s 1.9


center to inner duct 5.50545 tube

WRAP * number o f tubes * on side

2 * materials inside * tube material

* duct material * end of stainless steel region * End of geometry input

2 2

2 5 rest of space

* *

center to outer duct

5.81025 intersti tual material

2

* Superhistory option using 10 generation per superhistory * and nu multiplication factor = 1.0 SUPERHIST 10 1.0 * First stage Last stage Neutrons per stage time limit Source

* Starting source MULTIF ISS STD REGION 1 IN PART 1 / END CODE 5 FSCN*

-3 10 1000 160 -1 *

-50.00 50.00 440.0 50.00 50.00 440.0 -50.00 -50.00 440.0 -50.00 50.00 300.0 50.00 50.00 300.0 -50.00 -50.00 300.0 -50.00 50.00 200.0 50.00 50.00 200.0 -50.00 -50.00 200.0 -50.00 50.00 110.0 50.00 50.00 110.0 -50.00 -50.00 110.0 -30.00 30.00 110.0 30.00 30.00 110.0 -30.00 -30.00 110.0 -50.00 50.00 50.00 50.00 50.00 50.0 -50.00 -50.00 50.0 -50.00 1.00 440.0 50.00 1.00 440.0 -50.00 1.00 30.0 -50.00 8.00 440.0 50.00 8.00 440.0 -50.00 8.00 30.0 END

WHC-SD-FF-CSER-004 REV 1 P a g e 34

APPENDIX B

INDEPENDENT REVIEW CHECKSHEET

AND

R E V I E W E R ' S COMMENTS


CHECKLIST FOR lNDEPENDENT REVIEU

UHC-SD-FF-CSER-004 0 Docmen1 Checked . N h r :

T i t l e :

Revision: - CRITICALITY SAFETY EVALUATION FOR LONG TERM STORAGE OF F F T F FUEL I N INTERIM STORAGE CASKS

Yes No

[A [ I

[ I [ I

Problem Cmple te ly defined.

Appropriate ana ly t i ca l nethcd used.

Necessary assurprions are appropriate, e x p l i c i t l y stared, and supported.

C-uter codes and data f i l e s docunnted.

Data used i n caLc;:ations c x p i i c i r l y s ta ted i n docunnt.

Sources of non-standard formulasldsta a r e referenced and the correctness of the reference ver i f ied .

Data checked f o r consistency w i th o r i g i n a l source i n f o r M t i o n i s applicable.

n a t h m t i c a l der ivat ions checked inc lud ing dimensional consisrency of resul ts.

Models appropriate and used u i t h i n range of v a l i d i t y or use outside range Of established v a l i d i t y j u s t i f i e d .

Hand calculat ions checked f o r error.

Code run sfreams corrccr and consistent u i t h analysis docmentat ion.

Code output consistent u i t h input and w i th results reported i n analysis docmenration.

Acccprabi l i ry l i m i t s on ana ly t i ca l r e s u l t s appl icable and . . . L imi ts checked against sources.

Safety margins cc-L stent wi th good engineering pract ices.

Conclusions consistent wi th ana ly t i ca l results and appl icable l im i t s .

Results and conclusions address a l l points required i n the problem statement.

I have checked the analysls/caicular ions and 1s c c w l e t c and accurate to the best of ny knoul edge.

a 2 , L &!h- Date Englncer/Checker

Note: Any hand ca icu la t io rs . notes. or smmaries generated as par t of t h i s check should be signed, dated, and attached to t h i s checkl ist . narer la l Should be Labeled and recorded so that i t i s i n t e l l i g i b l e Io a techn ica l l y q u a l i f i e d t h i r d parry.

WHC-SD-FF-CSER-004, R E V 1 Page 36

REVIEWER'S COMMENTS

The t e c h n i c a l con ten t o f t h i s eva lua t ion was reviewed by A . L . Hess of t h e Consequence Analyses group, who provides t h e f o l l o w i n g comments.

T h i s e v a l u a t i o n f o r t h e c r i t i c a l i t y p o t e n t i a l f o r I S C storage o f i r r a d i a t e d FFTF f u e l s u f f e r i n g t h e e f f e c t s o f pos tu la ted "Dry Rot" i s comprehensive, and t h e var ious scenar ios s tud ied cover t h e range o f p l a u s i b l e f u e l r e d i s t r i b u - t i o n s should t h e c l a d and f u e l d i s i n t e g r a t e . Examination o f t h e MONK68 problem mode l l ing shows t h e represented geometries and composi t ions t o be conserva t ive . Th is reviewer concurs t h a t such d r y r o t e f f e c t s do n o t increase t h e r e a c t i v i t y cond i t ions t o a l e v e l where t h e r e q u i r e d s u b c r i t i c a l margins a re exceeded, w i t h i n t h e double-contingency c r i t e r i o n . For d r y cond i t ions , a c r i t i c a l i t y hazard cou ld o n l y be approached i f t h e f u e l was e f f e c t i v e l y separated from a l l c l a d and be compacted a t t h e bottom o f t h e assembly ducts i n a l l seven o f t h e DFAs i n a Core Component Container; these s t i p u l a t i o n s a re beyond p l a u s i b i l i t y .

For pin- loaded Ident-69 conta iners , a t most s i x C C C tubes c o u l d be loaded, each c a r r y i n g n o t more than 217 p ins (as i n a DFA, per l o a d i n g r u l e s ) . Consi- d e r i n g a l s o t h a t t h e Ident-69 components would no t s u f f e r Dry Rot, t h e un- f looded load ings o f p i n s i n t h e compartmented Ident-69 conta iners would be l e s s r e a c t i v e than d r y - r o t t e d DFAs i n the C C C tubes.

I t has been long recognized t h a t f u l l water f l o o d i n g c o n d i t i o n s migh t c rea te a c r i t i c a l i t y hazard w i t h Ident-69s loaded i n t o C C C tubes, e s p e c i a l l y w i t h a p i n count and l a t t i c e spacing combination which op t im izes moderation. The d r y r o t e f f e c t s i n such cond i t ions would no t n e c e s s a r i l y increase t h e hazard. How- ever, t h e m u l t i p l i c i t y o f t h e tube, conta iner and casks seals , which would have t o be breached t o admit water i n t o a l l f u e l reg ions, renders t h e f l o o d i n g c r i t i c a l i t y no t c r e d i b l e .

I n t h e course o f t h i s rev iew f o r d r y - r o t t e d DFAs i n seven C C C tubes, t he rev iewer s tud ied a l l o f t h e predecessor CSERs cover ing the load ings o f Core Component Containers i n var ious casks and p i t s , t o become f a m i l i a r w i t h t h e f u l l range o f load ing lcont ingency scenar ios. To a i d i n t h i s task , by a rev iewer r e l a t i v e l y new t o t h e FFTF f u e l storage c r i t i c a l i t y aspects , th ree t a b l e s were prepared t o summarize past c a l c u l a t i o n s . c a l c u l a t i o n s f o r DFA-loaded CCCs. d r y and w i t h water i ng ress . Tables 8.2 and 8 . 3 address Ident-69 loadings. The Monte-carlo cases i n these t a b l e s are o n l y those where t h e 36- inch f u l l he igh t o f f u e l i s re ta ined .

I n Table S.l, t he most r e a c t i v e case fo r d r y DFAs w i t h noma1 h e i g h t f u e l i s t h e bas ic c o n f i g u r a t i o n o f DFAs w i t h i n t a c t f u e l p ins i n seven C C C tubes ( k = 0.466) . The s i t u a t i o n where t h e f u e l c l a d and MOX p ins have d i s i n t e g r a t e d and are e f f e c t i v e l y homogenized ( b u t s t i l l 3 6 " h igh ) reduces k a few percent due t o t h e l o s s o f i n - p i n m u l t i p l i c a t i o n e f f e c t s . For t h e f looded cask w i t h seven DFAs. t h e b lend ing o f f u e l . c l a d and water f o r p ins s u f f e r i n g d r y r o t provides t h e h i g h e s t k (0 .82 ) , because o f the enhanced e f f e c t i v e -odera t ion .

Table 8.1 concerns

WHC-SO-FF-CSER-004, REV 1 Page 37

A t the r e q u e s t of t h i s rev iewer , t h e author submi t ted some a d d i t i o n a l ca lcu- l a t i o n s model l ing Ident-69 loadings in tubes of CCCs in t h e s t o r a g e casks . These added c a s e s , concerned w i t h loadings of more than 97 p ins per Ident-69 c o n t a i n e r , a r e i d e n t i f i e d i n Tables 8 .2 and 8 . 3 a s " e x t r a l - through e x t r a 7 " .

Table 8 .2 summarizes r e s u l t s from various CSERs f o r pin-loaded Ident-69s under unflooded s i t u a t i o n s . By opera t iona l r u l e s , each Ident-69 may n o t be loaded with more than 217 fue l p i n s , the same as f o r a d r i v e r fue l assembly in a CCC t u b e . More than l i k e l y , f o r i r r a d i a t e d f u e l , 217 p ins could not be emplaced because of bowing, bu t i t i s l i k e l y t h a t t h e r e would be more than t h e 97 p in count g i v i n g optimum modera tor / fue l r a t i o s in f looded c o n d i t i o n s . The " e x t r a " c a s e s i n Table 8 . 2 show what the e f f e c t s a r e o f s t u f f i n g more than the allowed numbers of p ins in an Ident-69 a s an e r r o r cont ingency . For c a s e " e x t r a l " , 321 p i n s a r e packed in each Ident 69 casing a t t h e same p i t c h a s i n a DFA, and f o r c a s e " e x t r a 3 " t h e r e a r e 490 p ins packed i n wi thout any wire wrappers . The c a s e s "ex t ra2" and " e x t r a 4 " , with 462 and 704 p i n s r e s p e c t i v e l y , modelled wire-wrapped and unwrapped p in packings d i r e c t l y i n s i d e the C C C tubes wi thout containment in Ident-69 c a s i n g s ; t h i s e r r o r c o n d i t i o n might be p l a u s i b l e f o r a few C C C tubes assuming a complete d is regard of procedures under l o s s of proper supervi s i on.

For t h e dry s t i p u l a t i o n on t h e Table 2 c a s e s , i t i s seen as expected t h a t the r e a c t i v i t y i n c r e a s e s a s number o f p ins wi th in the Ident-69/CCC tubes . l a t t e r t h r e e c a s e s , wi th p i n counts over 321 per t u b e and kef , va lues over 0 .80, r e p r e s e n t concurren t combinations of p in c o n d i t i o n s , o p e r a t o r e r r o r s and o v e r s i g h t f a u l t s ( i n c l u d i n g a loaded cent ra l C C C t u b e ) t h a t go beyond c r e d i - b i l i t y .

Flooded CCCs bear ing pin- loaded Ident-69s a r e r e p r e s e n t e d in the var ious Monte-carlo c a l c u l a t i o n s c i t e d in Table 8 .3 . loadings of p ins a r e used because when f looded the f u l l e r packings would be undermoderated. The " e x t r a 7 " c a s e near the bottom in Table 8 .3 has the al lowed 217 p ins spaced evenly t o f i l l the Ident-69 c a s i n g s in seven CCC tubes . In t h e l a s t c a s e , the p i n s a r e packed i n Ident-69s with wirewraps i n t a c t ( t h e p i t c h being the same as in a DFA d u c t ) , again in seven C C C t u b e s . The l a s t t h r e e c a s e s c e n a r i o s would not be p o s s i b l e without a d e l i b e r a t e c u t o f f of a Ident-69 c o n t a i n e r end t o make i t f i t i n t h e c e n t r a l C C C tube . The d i f f e r e n t i a l on k,,, f o r the c e n t e r tube being loaded i s about tl5X nk/k. Thus, t h e worst p l a u s i b l e conf igura t ion of s i x . pin- loaded Ident-69s in an ISC cask would not g ive a k - e f f e c t i v e exceeding 0.93 under f looding c o n d i t i o n s .

Reviewer's recommendations f o r t e x t c l a r i f i c a t i o n s and/or f u r t h e r e x p l a n a t i o n s and d e s c r i p t i o n s have been incorporated i n t o t h e r e p o r t . MONK68 input l i s t i n g s f o r some of t h e more c r u c i a l c a l c u l a t l o n s were checked and found t o a c c u r a t e l y p o r t r a y t h e c a s e d e s c r i p t i o n s (see a t t a c h e d c h e c k s h e e t ) .

The

For most of t h e s e c a s e s . l i g h t e r


Table 8.1: SUMMARY OF MONTE-CARLO CALCULATION RESULTS FOR FFTF FUEL ASSEMBLIES I N CORE COMPONENT CONTAINERS - :ODE (Report fear)

~- ~

MODELLING OF TUBES WATER

FLOODING CONDITION

REFLECTOR AROUND CCC CASING

CASE I?

CALCULATION RESULTS

PIN LATTICE DETAILS (36 i n c h f u e l he igh t

and v o i d

With Pins

6 -

Pins/ tube

k,,, S t d . Dev.

Tubes Present 6 DFAs i n 6 CCC

None

water i n SWT P i t

___- 0.2611 0.0010 1ccconttd A l l Dry

A l l Dry i n SDCV

217 29% Pu

217 29% Pu

217 29% Pu

YONK6B (1994) YCNP ( 1993) YONK68 (1994

MONK68 (1995)

SWTPAE 6 0.2878 0.0015 6 OFAs i n 6 CCC

6 DFAs i n 6 CCC

7 DFAs i n 7 C C C

7 DFAs i n 7 C C C

A l l Dry I S C case t concre te

0.3825 0.0013 h o t r o t 53h2

6

__ 7

7 __

217 292 Pu

A l l Dry None 0.3096 0.0010 1cccw 7dfad drydfas7

hexduct

hexduct

D r y r o t : Honiog . and v o i d

Fuel, c lad , tube ID duct . water

hexay. ,7214 DFA hexduct

D r y r o t : Fuel, c l a d and water hexduct homogenized D r y r o t : As above hexduct

I S C case t concre te


0.4660 0.0017

0.4352 0.0015

217 29x Pu

217 2 9 r Pu

A l l Dry

A l l Dry

MONK68 (1995) MONK60 (1995)

MCNP (1989)

cc7d f36d

7

__ __ 6

7 DFAs i n 7 CCC

1eIl1c-2 1tcm 0 . 2

6 DFAs i n 6 C C C

217 31% Pri a l l 239

0.670 0.01 Flooded

Water i n A l l Voids Water i n A l l Voids

water i n SWT P i t

water i n SWT P i t

I

SWTPAC 6

6 __

0.7034 0.0040 217 29% Pu

217 2Y6 Pu

6 DFAs i n 6 C C C

6 DFAs i n 6 C C C

MCNP (1993) MONK68 (1994)

MONK68 (1995)


0.7084 0.0026 h o t r o t 50h2

ccc7dfas 7 DFAs i n 7 CCC

217 29x Pu

Water i n A l l Voids


0.8201 0.0028


Table 8.2

SUMMARY OF MONTECARLO CALCULATION RESULTS FOR DRY FFTF FUEL-LOADED INDENT-69s I N CORE COMPONENT CONTAINERS - CODE (Report Year)

~~

MODELLING OF PIN LATTICE DETAILS TUBES (36 i n c h f u e l l e n g t h ) WATER

FLOODING COND I T 1 ON

CALCULATION RESULTS

k,,' Std Dev

REFLECTOR AROUND CCC CASING

CASE # With Tubes Array P i t $ Outer P ins/ I (cm) P:ns 1 Present I Type 1 Radius 1 t;Ie

6 ID69s Square 1.238 6.79 cm i n 6 C C C 29% Pu

A l l Dry Dry ISC case t concre te

0.2009 0.0078 MCNP (1991)

ID69v 15

0.2068 0.0049 ID69v16 A l l d r y

A l l Dry

A l l Dry

S o l i d Waste Cask, d r y I S C case t concre te

97 29x Pu

217 29XPu

MCNP

MONK68 (1991)

(1995)

MONK66 ext ra1

0.4660 0.0017 dry dfas7

p ins i n c c r

I S C case + concrete

0.6081 0.0020

A l l Dry 0.8070 0.0024 p i n s inccc

1SC case t concrete

I S C case t concrete

MONK68 ex t ra2

MONK68 ex t ra3

A l l Dry 0.8427 0.0025 p i n s i n c c r l p ins i n c c c l

A l l Dry 1.0862 0,0029 ISC case t concrete

MONK6B ext ra4

a)

b) No Ident-69s:

c )

0.7214 cm l a t t i c e p i t c h i s p i n spacing i n s i d e o f DFA hexduct; wrappers would have t o be absent.

f o r any lesser p i t c h , t he f u e l p i n w i r e Minimum p i t c h w/o wrap i s .5842 cm p i n diameter.

7-DFA case l i s t e d here t o show maximum k f o r 217 p i n s per CCC tube i n dry cond i t ions .

For these cases, f u e l p i n s would have t o be loaded d i r e c t l y i n t o the tubes o f t h e Core Component Container.

WHC-SD-FF-CSER-004, REV 1 Page 40

Table 8.3: SUMMARY OF MONTECARLO RESULTS FOR FFTF FUEL-LOADED INDENT-69s IN FLOODED CORE COMPONENT CONTAINERS - COOL

[Report Year)

KNP (1989)

CALCULAT:ON WATER

Dev

MODELLING OF PIN LATTICE DETAILS (36 inch f u e l he igh t ) TUBES

With Pins

6

-

-

CASE I Tubes Array P i t c h

0.970 0.01 Table 2 Case C . 1

6 ID69s square 1.011 i n 6 CCC 1 1 f u l l y f u l l water

f u l l y F1 ooded

f u l l y SDCV i n

6.63 cm 31% Pu a l l 239

6.79 cm

6.79cm 29% Pu

29% Pu

h igh since no 24OPu was assumed 0.8421 0.0067 1069~14 6

6 -

- 6

KNP (1991) MCNP (1991)

MCNP (1991) MCNP (1991)

0.8484 0.0055 1D69V

1069~14

i n 6 CCC I

6 ID69s Square 1.238 i n 6 C C C 6 1069s Square .7214, i n 6 C C C t r i n g .59 i n

o f 68 r i n g * 6 hex- hexag 1.270 ducts i n 6 CCC 6 ID69 square 1.238 i n 6 CCC 7 ID69 square 1.238 i n 7 CCC 7 ID69 .E779 i n 7 CCC hexag 7 1069s hexag ,7214 no CCC t h i s close, t h e i r w i r e wral

0.8511 0.0058

0.9127 0.0050 29% Pu

29% Pu f u l l y SDCV i n f looded f looded

CCC tubes 6" water but no t around

Water i n I S C case t A l l Voids concrete Water i n 1SC case t A l l Voids concrete

ID69vx 6

__ 6 7GG-p- f l a t t o 29% PU 0.9072 0.0030 MONK6A

(1991) ccco3

0.8651 0.0029 6 ccc6 id69wa ccc7 id69wa

MONK66 (1995) MONK66 (1995) MONK6B extra7 MONK6B extra6 -=7z

29% Pu

29% Pu

29% Pu 6.79 cm -321

29% Pu e rs would have t o

7

7 -

0.9927 0.0031

water i n i ISC case t i 0.9916 0.0030 pins i nccc f p ins i n c c r f

r i n g p ins

L A l l Voids concrete Water i n I S C case t 1.0762 0.0029 A l l Voids concrete

7

e absent.


Appendix C

Mixing FFTF Fuel Assemblies and Pin Containers in an ISC

Introduction and Summary

In order to minimize the number of ISCs required for dry storage, it is

The reason is that

necessary to mix up to seven FFTF fuel assemblies and pin containers in a single CCC inside an ISC. Previous analyses always assumed that FFTF fuel assemblies and pin containers would be stored separately. when moderated, pin containers are much more reactive than fuel assemblies particularly when in the center CCC position. Consequently, CCCs were restricted to either seven fuel assemblies or six pin containers with no pin container allowed in the center position.

By utilizing the seven positions of all CCCs, including those with pin containers, fewer CCCs and ISCs will be required for dry storage.

This appendix addresses mixing of FFTF fuel assemblies and pin containers with the utilization of all seven storage positions in a single CCC inside an ISC.

The results of the analysis show that an ISC containing a CCC with seven fuel components, of which no more than five are pin containers, and with no pin container allowed in the center position, is safely subcritical under fully moderated and reflected conditions.

System Description

The ISC storage system is described in the main body of this document.

Special Requirements and Controls

Pin containers are not allowed in the center storage position of a CCC. A CCC containing one or more fuel assemblies can have no more than five pin containers.

Analysis and Results

Calculations were made for every possible combination and arrangement of fuel assemblies and pin containers in an ISC. used for all calculations. for previous ISC analyses reported in the main body of this document.

that a pin container is stored in the CCC center position.

The MONK6B computer code was The computer inputs used were based on those used

Calculational set 1 assume The calculations are presented in two sets. This set is

WHC-SD-FF-CSER-004 R E V 1 Page 42

p resen ted i n Table C-1. Ca lcu la t iona l s e t 2 assumes t h a t a f u e l assembly i s s t o r e d i n t h e CCC c e n t e r p o s i t i o n . All c a l c u l a t i o n s assume i n t e r n a l water moderation and i n t a c t d u c t s . Fuel assembly p ins a r e assumed t o be a f f e c t e d by hot c e l l r o t and a r e comple te ly d i s i n t e g r a t e d . P i n c o n t a i n e r s , a s modeled, a r e op t ima l ly moderated. These c a l c u l a t i o n s bound t h o s e o f Table 5 , Sec t ion 5 .1 , s i n c e op t ima l ly moderated p in c o n t a i n e r s a r e more r e a c t i v e than fue l assembl ies .

For each s e t o f c a l c u l a t i o n s , t h e arrangement of p in c o n t a i n e r s and f u e l a s sembl i e s i n the o u t e r t ubes was va r i ed t o a s s u r e t h a t a l l p o s s i b l e c o n f i g u r a t i o n s were accounted f o r .

The c a l c u l a t i o n s p re sen ted i n Table C-1 a r e p re sen ted f o r completion and t o i l l u s t r a t e t h e a f f e c t on keff of load ing a pin c o n t a i n e r i n t o t h e c e n t e r s t o r a g e pos t ion . t u b e of a s e a l e d CCC because of i t ' s l e n g t h .

This s e t i s p re sen ted in Table C-2 .

P i n c o n t a i n e r s w i l l no t be loaded i n t o t h e c e n t e r p o s i t i o n o f a CCC.

A p in c o n t a i n e r i s prevented from r e s i d i n g in t h e c e n t e r In o rde r f o r a p in c o n t a i n e r t o

f i t i n t o t h e c e n t e r p o s i t i o n i t must be cu t t o a s h o r t e r l e n g t h . c o n t a i n e r s w i l l no t be c u t and shor t ened .

P i n

WHC-SD-FF-CSER-004 REV I Page 43

(a) dfa = fuel assembly, pc = pin container

Examination of the data presented in Table C-2 shows that with a fuel assembly in the center storage position up to five pin containers can be stored in the outer tubes of a CCC inside an ISC. As stated in Section 4.2 the effect on k, of small variations in CCC storage tube wall thickness is insignificant. under fully flooded and moderated conditions the k f f of this arrangement is less than 0.95 including bias and uncertainty. If the fuel assembly pins are modeled explicitly, keff is 0.9188 k 0.0028 (case m5pcx). An infinite array of ISCs loaded in this manner has a kef, of 0.9294+0.0031 (case m5pce).

An ISC containing a CCC with the above described loading of two fuel assemblies and five pin containers, all affected by hot cell rot, if internally moderated and tipped over on it's side may possibly have a keff increase as the fuel material spread out over a longer length. However, violation of several contingencies are necessary for this occurrence. First, all pins in the fuel assemblies and pin containers must be infected with hot cell rot. Next, the ISC outer seal, ISC inner seal and CCC seal all must fail


t o a l l o w any a v a i l a b l e water access t o t h e f u e l d e b r i s . Each seal f a i l u r e i s a separate cont ingency. Then t h e I S C must somehow become f looded. There i s no c r e d i b l e water source t h a t would r e s u l t i n f l o o d i n g o f an I S C . F i n a l l y , t h e I S C must be t i p p e d on to i t ' s s i d e i n o rder t o a l l o w t h e f u e l d e b r i s t o be spread over a l e n g t h s u f f i c i e n t t o p o s s i b l y inc rease kef,. c r e d i b l e mechanism t h a t cou ld cause an I S C t o f a l l over on i t ' s s ide . The o n l y imaginable way an I S C may end up on i t ' s s i d e i s i f somehow i t were t o f a l l o f f a t r u c k bed. Even i f t h a t were t o occur, t o t a l f l o o d i n g i s r e q u i r e d and t h e CCC seal and t h e two I S C sea ls must f a i l . The simultaneous occurrence o f these cont ingenc ies i s considered t o be h i g h l y u n l i k e l y , and t h e r e f o r e a kef, inc rease r e s u l t i n g f rom such a scenar io i s n o t c r e d i b l e .

There i s no

For moderated c o n d i t i o n s , as t h e number o f i n t a c t p i n s i n a p i n c o n t a i n e r inc reases above 97 and approaches 217, i t ' s r e a c t i v i t y decreases and approaches t h a t o f an f u e l assembly w i t h i n t a c t p i n s . For moderated c o n d i t i o n s , as t h e number o f d i s i n t e g r a t e d p i n s i n a p i n c o n t a i n e r inc reases above 97 and approaches 217, i t ' s r e a c t i v i t y increases and approaches t h a t o f an assembly w i t h d i s i n t e g r a t e d p i n s . F i v e such p i n c o n t a i n e r s i n a CCC w i t h two f u e l assemblies would be e q u i v a l e n t t o a CCC w i t h seven f u e l assemblies and bounded by t h e r e s u l t s o f Sec t ion 5.

A CCC w i t h s i x p i n c o n t a i n e r s i n t h e o u t e r s to rage tubes may n o t c o n t a i n a f u e l assembly i n t h e c e n t e r p o s i t i o n . Such an arrangement under f l o o d e d c o n d i t i o n s would exceed t h e 0.95 k,,,, i n c l u d i n g b i a s and u n c e r t a i n t y . empty s to rage l o c a t i o n would r e s u l t i n a l e s s r e a c t i v e CCC.

An

Cont ingency A n a l y s i s

I n o rder f o r t h e 0.95 keff l i m i t t o be exceeded, a t l e a s t f i v e cont ingenc ies must be v i o l a t e d . The cont ingenc ies are as f o l l o w s :

F lood ing o f t h e s to rage area - The I S C s w i l l be s t o r e d on a concre te pad above t h e f l o o d p l a i n and w i l l have environmental covers f o r p r o t e c t i o n f rom r a i n and snow.

F a i l u r e o f t h e I S C o u t e r seal - The I S C o u t e r seal would p revent water from reach ing t h e I S C i n n e r sea l .

F a i l u r e o f t h e I S C i n n e r seal - The I S C i n n e r seal would p revent water f rom reach ing t h e CCC.

F a i l u r e of t h e CCC seal - The CCC seal would keep water o u t o f t h e s to rage tubes.

Overbatching - Loading a p i n c o n t a i n e r i n t o t h e c e n t e r s to rage tube o f a CCC o r l o a d i n g a s i x t h p i n c o n t a i n e r i n t o a CCC w i t h a f u e l assembly i n t h e c e n t e r tube.


The occurrence o f a l l f i v e cont ingenc ies i s r e q u i r e d f o r keff t o exceed 0.95. w i l l remain l e s s than 0.95 i n c l u d i n g b i a s and u n c e r t a i n t y .

Wi th any combinat ion o f l e s s than f i v e o f these cont ingenc ies , kef f

Technical Peer Review

The t e c h n i c a l con ten t o f t h i s e v a l u a t i o n o f Rev is ion 1 t o WHC-SD-FF-CSER-004 was reviewed by K. D. Dobbin, who prov ides t h e f o l l o w i n g comments.

Rev is ion 0 eva lua ted t h e c r i t i c a l i t y p o t e n t i a l f o r I S C s to rage o f f u e l assemblies and Ident-69 p i n conta iners . It was found acceptab le t o p u t e i t h e r seven f u e l assemblies o r s i x p i n conta iners w i t h t h e c e n t r a l p o s i t i o n vacant i n each CCC loaded i n t o an I S C . Rev is ion 0 analyses were thorough ly reviewed, p r e v i o u s l y ,

For Rev is ion 1, a m i x t u r e o f f u e l assemblies and p i n c o n t a i n e r s was examined t o a l l o w t h e c e n t r a l p o s i t i o n t o be u t i l i z e d , thus making s to rage more e f f i c i e n t . Each o f t h e combinat ions o f f u e l and p i n c o n t a i n e r s which c o u l d f i l l a l l seven l o c a t i o n s i n a CCC was examined. From these, i t was concluded t h a t up t o f i v e p i n c o n t a i n e r s cou ld be loaded as l o n g as t h e r e are no p i n c o n t a i n e r s i n t h e c e n t r a l CCC l o c a t i o n . The rev iewer concurs w i t h t h a t conc lus ion , based on examinat ion o f t h e computer code i n p u t and o u t p u t o f t h a t l i m i t i n g case.

The rev iew c o n s i s t e d o f t h e f o l l o w i n g s i x i tems:

1) Changes t o t h e t e x t o f t h e main r e p o r t , WHC-SD-FF-CSER-004, were read t o v e r i f y cons is tency w i t h r e s u l t s ,

2 )

3 ) was checked,

4) t h e l i m i t i n g case was checked,

5) assemblies w i t h no p i n c o n t a i n e r i n t h e c e n t r a l l o c a t i o n has a k - e f f e c t i v e l e s s than 0.95 i n c l u d i n g biases and u n c e r t a i n t i e s ,

6) cont ingency c r i t e r i o n .

and are used as benchmarks f o r t h i s work.

The t e x t o f Appendix C was read f o r accuracy,

The l o g i c o f t h e sequence o f a l l p o s s i b l e mix combinat ions o f Table C-2

I n p u t t o t h e MONK6B computer code and t h e i n t e r p r e t a t i o n o f t h e o u t p u t f o r

Concurrence t h a t t h e l i m i t i n g case o f 5 p i n c o n t a i n e r s and two f u e l

The r e s u l t s were reviewed t o be conserva t ive w i t h respec t t o t h e double-

WHC-SD-FF-CSER-004 REV 1 Page 4 6

CHECKLIST FOR INDEPENDENT REVIEW

Document Checked - Number: UHC-SD-FF-CSER-004 Revision: 1 T i t l e : C r i t i c a l i t y Safety Evaluation f o r Lons Term Storage of FFTF Fuel i n In ter im Storaqe

Casks

N/A

[ I

[ I

[ I

[ I

[ I

d

[ I

d [ I

@4 [ I

[ I

[ I supported.

t d L 1 [ I

d [ I [ I

r d r 1 [ I

Problem Conpletely defined.

Appropriate analy t ica l method used.

Necessary assmptions a re appropriate, e x p l i c i t l y stated, and supported.

Computer codes and data f i l e s documented.

Data used i n ca lcu la t ions e x p l i c i t l y s ta ted i n document.

Sources of non-standard formulasldata are referenced and the correctness of the reference ver i f ied.

Data checked f o r consistency u i t h o r i g i n a l source information i s appl icable.

Mathematical derivations checked inc lud ing dimensional consistency of resul ts .

Models appropriate and used u i t h i n range of v a l i d i t y or use ourside range of establ ished v a l i d i t y j u s r i f i e d .

Hand ca lcu la t ions checked f o r e ~ r ' o ~ .

Code run streams correct and consistenr u i t h analysis documentation.

Code o u t w t consistent u i t h input and u i t h resul ts reporred i n analysis d o c w n t a t i o n .

Acceptab i l i t y l i m i t s on analy t ica l r e s u l t s appl icable and

Safety margins consistent u i t h good engineering practices.

Conclusions consistent u i t h analy t ica l r e s u l t s and applicable l i m i t s .

Results and conclusions address a l l po in ts required i n the problem statement.

. . . Limi ts checked against sources.

I have checked the ana lys is lca lcu la t ions and i t i s complete and accurate t o the best of my knouledge.

Note: Any hand calculat ions, notes. or sunnaries generated as par t of t h i s check should be signed, dated, and attached t o t h i s checkl ist. Mater ia l should be labeled and recorded so that i t i s i n t e l l i g i b l e t o a techn ica l l y q u a l i f i e d t h i r d party.

DISTRIBUTION SHEET

Name

To Dis t r ibu t ion

Text Text Only Attach./ EDT/ECN MSlN With All Appendix Only

Attach. Only

1 Ly;. Richard Page 1 of 1

EDT No. C r i t i c a l i t y Safe ty Evaluation f o r Long Term Storage of FFTF Fuel Project Title/Work Order

in Inter im Storaae Casks

Central F i l e s (1 t

J . E. Baker

M. D . Clements

K . D . Dobbin

J . Greenborg

S . W . H i l l e r

E . M . Mi l le r

S . L. Mischke

D . L. Nielsen

R . B. Packard

J . N . Pagl ie r i

P. R . Prevo

R . F . Richard

P. L. Scot t

R . 0 . Zimmerman I

~ f i / E ’ H L

o r i g i n a l ) ~3-88

N2-57

62-02

HO-35

HO-35

N2-02

HO-35

N2-11

N2-53

N2-02

N2-10

N2-10

HO-35

N2-02

N2-10

m Q 3 _ 1 &Z*

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

fl942 x

A-6000-135 (01/93) WEF067