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MISSISSIPPI POWER & LIGHT COMPANYHelping Build Mississippi

EdhhihhMid5 P. O . B O X 164 0, J A C K S O N. MIS SI S SI P PI 3 9 2 0 5

'p=oouction oceaavus*T July 8,1980

U.S. Nuclear Regulatory Cotnission.

Licensing Branch No. 3Division of LicensingOf fice of Nuclear Reactor RegulationWashington, D. C. 20555

Attention: Mr. A. Schwencer , Acting Chief

Dear Mr. Schwencer:

SUBJECT: Grand Gulf Nuclear StationUnit s 1 and 2

Docke t Nos . 50 -4 16/4 17File 0272/0277/L-334.0Partial Transmittal ofResponses to Draf t SERfor FSAR Sections 3.6through 3.10 (Package 2)

AECM-80 /150

Our letter of June 20, 1980, transmitted our proposed agenda for the upcomingmeeting with Mechanical Engineering Branch personnel to resolve open issuesin the Dr'ft Safety Evaluation Report (DSER) . In that agenda some thirty-two(32) items were identified as open issues requiring a response or action by l

Mississippi Power and Light (MP&L) .

The responses to twenty-two (22) items were forwarded to you on July 2,1980,by our letter AEQi-80/149. The responses to the remaining (ten) 10 items are attached.

Yours truly,

~,---- hd^L. F. DaleNt. clear Project Manager

JGC/JDR/mb i

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80 0 7I40 3Jf Member Middle South Utilities System

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'U S. . Nu11 ear Regulatory Commission ' -2- July 8. 1980AECM-80/150

Attachments: DSER Item Nos. :,

1. 3.7.3-12. 3.7.3-2 - -

3. 3.9.2-24. 3.9.2-85. 3.9.3-16. 3.9.3-37. 3.9.348. 3.9.5-19. 3.9.5-2

10. 3.9.6-1

cc: Mr. N. L. StampleyMr. R. B. McGeheeMr. T. B. Conner

Mr. Vic tor Stello , Jr.t DirectorDivision of Inspection & EnforcementU. S. Nuclear Regulatory Commission '

Washington, D. C. 20555

Mr. Merv BamptonPacific Northwest LaboratoryRichland. Boulevard ,

* Richland, Washington 99351

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DSER 3.7.3-1DSER Page 7-

OPEN ITEM

" Standard Review Plan Section 3.7.3, " Seismic Subsystem Analysis," requires fiveOBEs udth a minimum of 10 cycles each to be utilized in fatigue evaluation. This

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requirement has not been met. The applicant must justify this deviation fromStandard Review Plan 3.7.3 or commit to meet our requirements."

RESPONSE

1 One OBE with 10 cycles has been approved as a licensing basis for other plants. Thebasis for acceptance is the low probability of occurrence of a single earthquake ofOBE intensity. During a 40 year life , it is probable that five earthquakes withintensities one-tenth of the SSE intensity, and one earthquake with approximately20% of the proposed SSE intensity, may occur. Therefore , the probability of evenone OBE intensity earthquake (50% of SSE intensity) occuring is extremely low.

Further study of strong motion in earthquakes shows- that the use of 10 cycles isconservative. Studies show that there are only 2 to 3 peak magnitude cycles.

MP&L ACTION;

None.

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DS ER - 3. 7. 3-2DSER Page 7

OPEN ITEM ,

" Regulatory Guide 1.92, " Combining Modal Responses and Spatial Componentsin Seismic Response Analysis,'' outlines the procedures for combining modalres ponses . Specifically, modes having frequencies falling within 107. of eachother are defined as closely spaced modes and must be combined by the absolute ~

sum method. Our review of FSAR Section 3.7.3 cannot be completed untilassurance is provided that this criterion has been met or that an equivalentlevel of safety hss been achieved."

RESPONSE

The Grand Gulf commitment to Regulatory Guide 1.92 is presented in FSAR Page3 A/1. 92-1. As indicated there , the treatment of closely spaced modes is dis-cussed in FSAR Subsection- 3.7.3.7.2.2, Page 3.7-38.

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In general, either time-histories or response spectrum methods of analyses areused for seismic analysis. When the time history method is used , the vectorsum at every time step will be used to calculate the maximam response. Theuse of the time-history analysis method precludes the need to consider closely'spaced modes . When the response spectrum method is used, the responses forclosely spaced modes are combined using the double sum method as describedin Reference 8 of FSAR Section 3.7.5 . This method was approved by the NRCon the' GESSAR 251 docket.

MP&L ACTION

A review of FSAR Subsection 3.7.3.7.2.2 has revealed an editorial error in theequation describing the double sum method used by Grand Gulf. Subsection 3.7.3.7.2.2will be amended to correct that error.

The corrected equation, consistent with Reference 8 of FSAR Section 3.7.5. isp esented below:

N N 1/2

[ RR= k si Km. s=1 ks

where

R Representative maximum value of a particular response of a given=

element to a given component of excitation

thPeak valae of the response of the element due to the k modeR =k.

Number of s'ignificant modes considered in the modal responseN =

combination -

thPeak value of the response of the element attributed to sR *s .

mode,

1 Singh, A.K. , et al., " Influence of Closely Spaced Modes in Response Spectra Methodof Analysis ," published in - ASCE ' Specialty Conf erence on Structural Design ofNuclear Plant ' Specialties , ' December 1973.

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Also,"

I 2 -1q '(g{~ - W[)d1+=

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ks p gW *k s s., d.

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;in which:

. 1/22W( "% 1 -f k pk'=f + 2k, E8dk

where

4 w = Modal frequency in the kth mode'k<

p = - Damping ratio in the k th mode.

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;. td. = Duration of the earthquake

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DSCR-3.9.2-2DSER Page 13

OPEN ITEM,

"We do not approve the GE acceptance criteria for steady-state piping vibrationor for transient snubber loads. GE stated that the piping stress due to vibration,woul.d be maintained below the ASME Code upset limit for primary stress. We believethat the allowable piping stress due to steady-state vibration should be set atsome percentage of the material endurance limit. Since the transient events in thistest program are expected to occur repeatedly throughout the plant life , we believethat the acceptable snubber load should be the snubber's upset load rating, not itcultimate capacity."

RESPONSE

Acceptance critorion is divided into two categories: Level 1 and Level 2. If Level Icriterion is violated, testing must be placed on hold. If Level 2 criterion is vio-lated , the testing can continue , but the measurements must be evaluated to verify thatcontinued test operation will not result in exceeding the piping fatigue requirements.For steady state vibration the piping peak stress due to vibration only (neglectingpressure) will not exceed 10,000 psi for Level 1 criterion and 5,00C psi for Level 2criterion. These limits are below the piping material fatigue endurance limits.From the ASME Code, Section III, Appendix 1, the material fatigue endurance limitsfor carbon steel and stainless steel are 13,000 psi and 25,000 psi, respectively.

For operating transient vibration, Levr,12 criterion is based on pipe stresses andsupport loads not to exceed design basis predictions. Design basis criteria requirethat operating transient stresses and loads not to exceed any of the Service Level Blimits including primary stress limits, fatigue usage factor limits, and allowableloads on snubbers.

MP&L ACTION

None.

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DSER-3.9.2-8DSER Page 18

OPEN ITEM

"The applicant has analyzed the reactor, its internals, and unbroken loops of thereactot coolant pressure boundary,. including the supports, for the combined loads

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due te a simultaneous loss-of-coolant accident and safe shutdown earthquake. Wecannoc complete our review in this area until the applicant submits the informationreqvasted in Question 110.29."

RESPONSE

The New Loads program for Grand Gulf will provide the analyses results requested.

,MP&L ACTION

Submit analyses results upon completion.of New Loads program.

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DS ER-3. 9. 3-1DSER Page 20

OPEN ITEM

"This one exception is that the applicant has not included the combined stressesdue to SRV and OBE loads in its fatigue calculations. We realize that a position "

such as the applicant's was accepted during the review of GESSAR. Upon reconsider-ation, however , we feel that the fatigue contribution attributable to combined SRVand OBE loads should be addressed for those lines whose failure may result inunacceptable consequences such as bypass of the suppression pool. We consider thisto be an open issue."

RESPONSE

We believe that the loading combination OBE + SRV (Load Case 2) should be considered *.as an Emergency condition. The classification of this low probability combinationof loads as Emergency (Service Level C requirements) is consistent with 1) theencounter frequency of the OBE, 2) the number of combined stress cycles expectedover the plant lifetime, and 3) the intent of the ASME code. As a conservativemeasure , we have agreed to meet Upset limits (Service Level B requirements) withoutfatigue analysis. The considerations for not conducting the fatigue analysis involve

,the same technical justifications enumerated above.

yP&L ACTION

None.

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'DSER-3.9.3-3DSER Page 21

OPEN ITEM

"Some of the data in FSAR Table 3.9-2 are missing and the applicant indicatesthet~the data will be supplied in amendment to the FSAR. We cannot complete our

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review until this data is available."

RESPONSE

The New Loads program for Grand Gulf will provide the analyses results requested.

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Submit analyses results upon completion of New Loads program.

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DS ER-3. 9. 3-4DSER Page 22

OPEN ITEM

"As discussed in our letter to General Electric Company dated January 28, 1980,we have accepted the applicant's proposal to cut and cap the control rod drive

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return line. More detailed discussions of these issues will be found in theTask Action Plan A-10 final report to be published shortly as NUREG-0619."

RESPONSE

Design changes are presently in progress or have been completed to incorporatemodifications proposed by the General Electric generic resolution in this issue.

MP&L ACTIONSs.

All necessary design changes required for compliance with the generic resolutionwill be accomplished.

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DSER - 3.9.5-1DSER Page 29

OPEN ITEM'

" Modes having frequencies failing within 107. of each other are defined as closelyspaced modes and should be combined by the absolute sum method. Our review ofFSAR Section 3.9.5 can not be completed until assurance is provided that this *

criterion has been met or t' e.t an equivalent level of safety has been achieved."

RESPONSE & MP&L ACTION

See response to DSER Itan No. 3.7.3-2.

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DS ER-3. 9. 5-2DSER Page 29

OPEN ITEM

"The applicant states that the f act that no plastic deformation occurs in thereactor internals components during emergency or faulted conditions demonstratesthat no mechanical interferences exist. We do not necessarily agree that not

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allowing plastic deformations will assure no mechanical interference. It is ourposition that even elastic deformation must be checked to provide this assurance."

RESPONSE

Elastic behavior is considered in the design of components inside the reactorpressure vessel which can af fect the insertability of the control rods. Plasticdeformation of a particular component is also permitted up to the limits (includingappropriate safety f actor) where control rod insertability has been demonstratedby prototype scram tests.

- MP&L ACTION

FSAR-subsection 3.9.5.4.4 will be revised to incorporate the above response.

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DSER-3.9.6-1DSER Page 31

OPEN ITEM

"The applicant has not yet submitted its program for the preservice and inservicetestinF of Pumps and valves, as requested by Question 110.40; therefore, we have - -

not yet completed our review."

RESPONSE

Preservice testing of safety related pumps and valves will be accomplished aspart of preoperational equipment testing. Preservice testing provides thebaseline information_ required for inservice inspection program. Currently, theinitial 120 month inservice inspection program for pumps and valves will besubmitted in February, 1981.

MP&L ACTION

Submit pump and valve inservice inspection program as requested.

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