cohp-821155—6 de83 007724 kuca critical experiments

25
COHP-821155—6 DE83 007724 KUCA CRITICAL EXPERIMENTS USING MEU FUEL vll) Keiji KANDA, Masatoshi HAYASHI, Seiji SHIROYA, Keiji KOBAYASHI, Hiroshi FUKUI, Kaichiro MISHIMA, and Toshikazu SHIBATA Research Reactor Institute, Kyoto University, Kumafcori-cho, Sennan-gun, Osaka 590-04, Japan DISCLAIMER This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsi- bility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Refer- ence herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recom- mendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. NOTICE PORTIONS OF THIS REPORT ARE ILLEGIBLE^ To be submitted to the International Meeting on Research and Test Reactor Core Conversions from HEU to LED Fue.1s ( Argonne National Laboratory, November 8-10, 1982 DISTRIBUTION OF THiS DOC'MHI IS

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Page 1: COHP-821155—6 DE83 007724 KUCA CRITICAL EXPERIMENTS

COHP-821155—6

DE83 007724

KUCA CRITICAL EXPERIMENTS USING MEU FUEL vll)

Keiji KANDA, Masatoshi HAYASHI, Seiji SHIROYA,

Keiji KOBAYASHI, Hiroshi FUKUI, Kaichiro MISHIMA,

and Toshikazu SHIBATA

Research Reactor Institute, Kyoto University,

Kumafcori-cho, Sennan-gun, Osaka 590-04, Japan

DISCLAIMER

This report was prepared as an account of work sponsored by an agency of the United StatesGovernment. Neither the United States Government nor any agency thereof, nor any of theiremployees, makes any warranty, express or implied, or assumes any legal liability or responsi-bility for the accuracy, completeness, or usefulness of any information, apparatus, product, orprocess disclosed, or represents that its use would not infringe privately owned rights. Refer-ence herein to any specific commercial product, process, or service by trade name, trademark,manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recom-mendation, or favoring by the United States Government or any agency thereof. The viewsand opinions of authors expressed herein do not necessarily state or reflect those of theUnited States Government or any agency thereof.

NOTICE

PORTIONS OF THIS REPORT ARE ILLEGIBLE^

To be submitted to the International Meeting on Research and Test Reactor CoreConversions from HEU to LED Fue.1s( Argonne National Laboratory, November 8-10,1982

DISTRIBUTION OF THiS DOC'MHI IS

Page 2: COHP-821155—6 DE83 007724 KUCA CRITICAL EXPERIMENTS

KUCA CRITICAL EXPERIMENTS USING MEU FUEL (II)

Keiji KANDA, Masatoshi HAYASHI, Seiji SHIROYA,Keiji KOBAYASHI, Hiroshi FUKUI, Kaichiro MISHIMA,

and Toshikazu SHIBATA

Research Reactor Institute, Kyoto University,Kumatori-cho, Sennan-gun, Osaka 590-04, Japan

Introduction

Due to mutual concerns in the USA and Japan about the proliferation

potential of highly-enriched uranium (HEU), a joint study program wasinitiated between Argonne National Laboratory (ANL) and Kyoto UniversityResearch Reactor Institute (KURRI) in 1978. In accordance with the reducedenrichment for research and test reactor (RERTR) program, the alternativeswere studied for reducing the enrichment of the fuel to be used in the Kyoto

2University High Flux Reactcr (KUHFR). The KUHFR has a distinct feature inits core configuration : it is a coupled-core. Each annular shaped core islight-water-moderated and placed within a heavy water reflector with a certaindistance between them. The phase A reports of the joint ANL-KURRI program

3 4independently prepared by two laboratories in February 1979, ' concluded thatthe use of medium-enrichment uranium (MEU, k 5Z) in the KUHFR is feasible,pending results of the critical experiments i» the Kyoto University Critical

Assembly (KUCA) and of the burnup test in the Oak Ridge Research Reactor

(ORR).6

An application of safety review (Reactor Installation License) fr>r MEUfuel to be used in the KUCA was submitted1 to the Japanese Government in March1980, and a license was issued in August 1980. Subsequently, the applicationfor 'Authorization before Construction* was submitted and was authorized inSeptember 1980. Fabrication of MEU fuel elements for the KUCA experiments byCERCA in France was started in September 1980, and was completed in March1981. The critical experiments in the KUCA with MEU fuel were started on asingle-core in May 1981 as a first step. The first critical state of the coreusing MEU fuel was achieved at 3:12 p.m. in May 12, 1981. After that, thereactivity effects of the outer side-plates containing boron burnable poisonwere measured.

At Julich Meeting in Sept., 1981, we presented a paper on critical mass

and reactivity of burnable poison in the MEU core. Since then we carried outo

the following experiments: (1) temperature coefficient, (2) flux9 9

distribution, and (3) void coefficient.

Due to a minor change of the KUHFR core design, the pitch of fuel plateswas changed from 3.84 mm to 3.80 mm. Although'in the present experiments,both fuel pitches were seen as shown in Table 1, the 3.80 mm pitch would beused thereafter.

Page 3: COHP-821155—6 DE83 007724 KUCA CRITICAL EXPERIMENTS

Table 1. Pitch of the fuel plates.

experiment

Critical Mass

Burnable poison

Jiilich (1981)

3.84 mm

3.84 mm3.80 mm

Temperature Coefficient

Flux distribution

Void effect

Experiments

ANL (1982)

3.30 mm

3.84 mm

3.84 mm

3.84 mm3.80 mm

Core Configuration

Figure 1 shows the view of the heavy water tank made from aluminum forthe single-core experiments. Figure 2 shows the fuel elements assembled in acylindrical fora, which is installed in the heavy water tank. The annularshaped core is light-water-aoderated and placed within a heavy water

reflector. The core has a cylindrical center island of light water. Thefuel region is divided into two parts by the space for control rods, which arecalled the inner and outer fuel regions, respectively. The inner regionconsists of 6 fuel elements, while the outer region consists of 12 elements.Each fuel plate which has some curvature, can be inserted one by one betwaenaluminum side-plates. Figure 3 illustrates the fuel plate and side-plates.For the KUCA critical experiments using MEU fuel, the boron loaded side-plateswere fabricated. The plane cross-section of the assembly looks like aJapanese fan or a kind of cake called Baumkuchen.

The core configuration employed in this work was called C38R(BK D.0)HEU

and is illustrated in Figs. 4 and 5. The outer fuel elements were numbered asOUT-01 or EX-01, 0UT-02 or EX-01 and so on, while the inner as IN-01, IN-02and so on. The maximum numbers of fuel plates which can be loaded in theouter and inner fuel elements are 17 and 15 per element, respectively. Thecore was mainly controlled by two rods, namely C2 and C3 rods, because allsafety rods were withdrawn to the upper limit at each operation and Cl rod wasapart from the core. The detectors were arranged around the heavy water tank.The neutron source was located under the heavy water tank.

Critical Mass

The critical approach of the core, which all side-plates contained noburnable poison and the pitch between the fuel plates was 3.80 ma* wasperformed by the inverse multiplication method. The critical state of theC38R(BK D2O)MEU core was achieved with 262 fuel plates of 3.80 mm pitch. This

number of fuel plates was the sane for the 3.84 mm pitch core illustrated in

Page 4: COHP-821155—6 DE83 007724 KUCA CRITICAL EXPERIMENTS

235Fig.4. The masses of U and (I were also 4165.74 g and 9284 g, respectively.The excess reactivity measured by the positive period was 0.077 ZAk/k. Usingthe measured mass reactivity coefficient for the fuel plate (0.018

235ZAk/k/g- U), the least critical mass of the core was estimated as 4162235

g- U or 9276 g-U. These results are listed in Table 2.

Table 2. The results of critical mass.

MEU

MEU

HEU

fuel

(44.

(44.

(93.

87Z)

87Z)

14Z)

pitch(mm)

3.80

3.84

3.84

numberof

plates

262

262

276

0-235

(8)

4165.74

4165.74

3524.46

U

(g)

9284

9284

3784

excessreactivity

(ZAk/k)

0.077

0.211

0.468

The change of fuel plate pitch caused a slight change in excessreactivity, due to spectral hardening.

Neutron Flux Distributions

For the measurement of neutron flux distributions, the activation foiltechnique was employed. Gold wires, with and without a cadmium sheath wereactivated. Relative neutron flux distributions were obtained for variouspositions in the core with and without a void at the center of the reactor.The values of reflector savings were obtained for a few positions in the corewithout the void. The positions of foil irradiations in the C38R(BK D.0)MEU

core are shown in Figs. 5 and 6 with its configuration. From these figures,the differences of distributions between two cores are seen at the centerisland region and the outer fuel region. In Fig. 5, all fuel elements exceptone outer element contain boron burnable poison. An acrylic void tube of 10cm o.d. and 9.2 cm i.d. is located at the center island. In Fig. 6, one halfof outer fuel elements contain no burnable poison and there is no void at thecenter island. Two hundred and ninety four fuel plates are fully loaded inboth cores. The numerical symbols (1 **• 11) in Figs. 5 and 6 indicate thepositions where gold wires were set vertically. The alphabetical symbols (a *>p) indicate gold wires set horizontally.

Bare gold wires of 0.5 mm diameter were set at all positions. To obtainthermal-neutron flux distributions, gold wires covered with cadmium sheaths (0.5 mm thick and 1 mm i.d. ) were set as shown in Fig. 6. The gold wires wereirradiated at approximately 1 W. Each irradiation time was 30 minutes. Afterthe irradiations, gold wires were cut into small pieces ( 1 ^ 2 cm). The

198gamma-rays emitted from the decay of Au were counted with an automaticsample changer in which a well-type Nal(Tl) scintillator was installed. The

Page 5: COHP-821155—6 DE83 007724 KUCA CRITICAL EXPERIMENTS

weight of each piece of gold wire was measured. The counts measured by the198

automatic sample changer were corrected with the decay of induced Auactivities to obtain values proportional to the saturated activities. Thosevalues were normalized by the weights of gold wires and by the reactor powerlevels of irradiations. The difference between such values with and without acadmium sheath was assumed to represent a relative flux of thermal neutrons.

Horizontal Neutron Flux Distributions

The horizontal neutron flux distributions are shown in Figs. 7, 8, 9 and10. These neutron flux distributions were measured in the core with theacrylic void tube at the center island.

Figures 7 and 8 show the neutron flux distributions in the fuel regionand in the heavy-water reflector, respectively. In Fig. 7, neutron fluxdistributions (j * m) measured at the middle height of fuel plates between theside-plates, have some depressions in the fuel region. The reason is that theside-plates contained boron burnable poison. In the void region, the fluxdistribution (g) is flat. At the outside of the inner fuel region, the fluxdistribution (f) measured on the top of fuel plates was reduced more than thatof (i). It is because there was the lower edge of the safety rod S4 near thatposition, though S4 was withdrawn to its upper limit. In Fig. 8 , the neutronflux in heavy-water reflector, measured at 44 mm below the middle height offuel plates, has no peak and decreases rather rapidly with the distance fromthe center of the core. This phenomenon reflects the facts that there is alight-water gap of approximately 2.5 -m thick between the outer fuel regionand the heavy-water tank and 30 cm thick layer of heavy-water is notsufficient for a neutron reflector.

Figures 9 and 10 show the neutron flux distributions at the middle heightof fuel plates along the inner circular direction of the inner fuel region andalong the outer circular direction of the outer fuel region, respectively. InFigs. 9 and 10, there are peaks near the side-plate regions, though theregions contain boron burnable poison.

Vertical neutron flux distributions

The vertical neutron flux distributions in the core with a void at thecenter island are shown in Figs. 11, 12 and 13; those for the core withoutvoid in Figs. 14 and 15. Asymmetric features were observed in all of thevertical distributions. Namely, the neutron flux near the upper edge of fuelplates was higher than that near the lower edge. The reason was that thethickness of light- or heavy-water layer was not the same at the upper andlower site. At the upper site it was much thicker. In addition to that,there were layers of other materials such as aluminum and stainless-steel atthe lower site. These materials are not favorable for the reflection ofneutrons. In fact, neutrons are strongly absorbed in the stainless-steellayer.

Figure 11 shows the neutron flux distribution in the heavy-waterreflector. The irregular points near the peak in Fig. 11 might be caused bythe horizontal aluminum pipe installed in the heavy-water tank for themeasurement of neutron flux distributions.

Page 6: COHP-821155—6 DE83 007724 KUCA CRITICAL EXPERIMENTS

Figure 12 shows the neutron flux distributions in the inner fuel region(between IN(B)-05 and -06) and outer fuel region (between EX-C1 and -02,OUT-07 and EX-08). In Fig. 12, the neutron flux (7) in the inner fuel regionis larger than those of (6) and (8) in the outer fuel region. The differencebetween (6) and (8) in the outer fuel region was caused by the OUT-07 elementwhich contains no boron burnable poison.

Figure 13 shows the neutron flux distributions in the center islandtinner fuel region (IN(B)-06) and outer fuel region (EX-01, OUT-07). Figure 14shows the neutron flux distributions in the center island, outer fuel region(OUT-11) and heavy-water reflector. In Figs. 13 and 14, the neutron flux inthe center island is distinctly higher than the others for either core withand without a void.

The thermal neutron flux distributions are shown in Fig. 15 in the centerisland, outer fuel region (OUT-11) and heavy-water reflector.

Reflector savings

Neutron flux distributions measured with cadmium sheath were fitted bythe least square technique to a ccsine curve and reflector savings wereobtained as follows:

y=Acos(B(x-C)),

where

A, B, C : constants for a cosine fit,y : neutron flux,x : distance from the surface of grid plate (cm).

As the length of the fuel meat was 60 cm, the axial reflector savings 6 (cm)was obtained from the following equation,

«=(§ - 60)12.

These results are listed in Table 3. Table 3 shows that the extrapolationdistance in the heavy-water reflector is larger than those in the fuel and thecenter island of light-water, while the center position of the fluxdistribution, C, is same in all regions.

Page 7: COHP-821155—6 DE83 007724 KUCA CRITICAL EXPERIMENTS

Table 3. Axial reflector saving and extrapolation distance.

A 2 B C 6(n/sec*cm ) (I/cm) (cm) (cm)

_2heavy water reflector 0.27 3.949x10 40.4 9.8+0.3

outer fuel region 1.01 4.158xlO~2 40.2 7.8+0.1

center region 9

of light water 1.01 4.119xlO~'i 40.0 8.1+0.1

Temperature Coefficients

The temperature reactivity coefficients were measured for two coreconfigurations. One had an acrylic void pipe at the center island of lightwater and the other had no such a void. The outer diameter of the acrylicvoid pipe was 100 mm and the inner diameter was 92 mm. In advance of themeasurements, 294 fuel plates were fully loaded in the core. The criticalitywas adjusted by the number of side-plates containing burnable poison. All ofthe inner and one half of the outer fuel elements contained poison, while, inthe core with the acrylic void pipe, all the fuel elements except only oneouter element contained burnable poison. The temperature of light and heavywater were raised simultaneously by the electric heater installed in bothregion and was adjusted to be the sama in both regions. The temperatures ofseveral locations in the core were monitored by the thermocouples set there.The excess reactivities of the core at seven temperatures from 20 °C to 70 °Cwere measured by the positive period method and the temperature coefficientsof the core were obtained. In Fig. 16, the temperature reactivitycoefficients are shown.

For the core without void, the temperature coefficient was positivebeyond 70 °C, while it changed sign from positive to negative at approximately33 °C for the core with.acrylic void pipe at the center island of light water.Two curves of the temperature coefficients were almost parallel to each otherand both curves tended to be linear beyond 35 °C. The difference between the

two was approximately 9 x 10~ Ak/k/°C.

Reactivity Effects of Void

The reactivity effects of a void were measured by two different methods.The one was that aluminum pipe was employed to simulate the void in the 3.84mm pitch cores The other was that a N_ gas bubbling was employed in the 3.80mm pitch core.

The reactivity effects of a void, simulated by aluminum pipe, weremeasured at four locations in the 3.84 mm pitch core, 294 full loaded. The

Page 8: COHP-821155—6 DE83 007724 KUCA CRITICAL EXPERIMENTS

location? were (1) the middle of the cylindrical center island of light water,(2) the space for control rods, (3) the light water gap between the heavywater tank and the outer fuel region and (4) the middle of the heavy waterreflector. Aluminum void pipes of several diameters were employed to simulatethe void. The excess reactivity was measured before and after pouring lightor heavy water into the pipe by the positive period method. The differencebetween two reactivities before and after the injection corresponded to theeffects of the voids.

The reactivity effects of voids measured at four locations using aluminumpipes are tabulated in Table 4. In the control rod space and at the middle ofthe heavy water reflector, the reactivity effects of voids were negative.While they were positive at the other locations. The void coefficient was

—5 3estimated as approximately 1 x 10 Ak/k/cm at the middle of the center

island of light water, -5 x 10~ Ak/k/cm at the space for control rods, 2 x

10 Ak/k/cm at the light water gap region between the outer fuel region and

the heavy water tank and -2 x 10~ Ak/k/cm at the middle of the heavy waterreflector, respectively.

Table 4. Reactivity Effects of Aluminum Void Pipes.

locations in the coreouter diameter

( cm )

inner diameter

( cm )

void reactivity

( ZAk/k )

middle of the center

island of light water

1.0

2.5

2.5

2.5

2.5

4.0

0.71.9

2.1

2.2

2.3

3.38

0.0249

0.171

0.212

0.231

0.245

0.538

space for control rods 1.0 0.7 -0.0109

light water gap betweenthe outer fuel regionand the heavy water tank

1.0

2.5

0.7

2.3

0.0042

0.0632

middle of the

heavy water reflector

3.5

6.5

9.0

2.95.5

8.'*

-0.0096

-0.0303

-0.0781

Page 9: COHP-821155—6 DE83 007724 KUCA CRITICAL EXPERIMENTS

The experiment of reactivity effects of void, simulated by N? bubbling,

consisted of an in-pile" experiment on reactivity measurement and anout-of-pile calibration on* void fraction. The reactivity effects of void weremeasured at six locations in the 3.8 mm pitch core, and measured in twodifferent cores, with and without burnable poison. The voids were -produced inthe fuel elements by bubbling N_ gas through a small needle-like nozzle which

was placed at the bottom of a fuel plate. Figures 17 and 18 show the coreconfigurations. The differences between the cores shown in Figs. 17 and 18are seen at the inner and outer fuel regions. In Fig. 17, strainless steeltubes at the space for control rods between IN-02 and EX-07, -08 were utilizedfor adjusting the excess reactivity of this core. In these cores,measurements of reactivity as a function of N. gas flow rate were made in the

two fuel elements, IN-02, EX-04 (or IN(B)-02, EX(B)-04). The position of theN_ gas outlet nozzle is shown in Fig. 19. With and without the N gas

flowing, the excess reactivity was measured by the positive period method.The difference between the two measurements gives the reactivity for each N.

gas flow rate. The relation between flow rate and void ratio is now beingmeasured by an out-of-pile experiment.

The results for various flow rates are shown in Figs. 20 and 21 and inTables 5 and 6, where the space dependency of void coefficient is clearlyobserved. It is explained by the change of neutron spectra in the measuredlocations. The location close to the moderator region, has a soft neutronspectrum; the other has a hard neutron spectrum. The difference in voidcoefficient by burnable poison is also observed.

The comparison between experiments and calculation will be done inseparate papers. The critical experiments with MEU fuel on a coupled core,including measurement of dynamic parameter, will be follow as mock-upexperiments for the KUHFR.

Acknowledgement

The authors wish to thank Mr. Toshimitsu Sagane and other members of theKUCA for their generous help and cooperation in the experiments. They arevery grateful to Dr. Manuel M. Bretscher of ANL, Prof. Yuichi Ogawa's group ofHokkaido Univ., Prof. Kojiro Nishina's group of Nagoya Univ., Prof. RyotaMiki's group of Kinki Univ. and Prof. Kazuhiko Kudo's group of Kyushu Univ.for their cooperation in the experiments. They wish to thank the members ofthe Technical Committee of the KUCA chaired by Prof. Hiroshi Nishihara ofKyoto Univ. for their advice and support in this work.

Page 10: COHP-821155—6 DE83 007724 KUCA CRITICAL EXPERIMENTS

Table 5. Void reactivity for the flow rate in C38R(BK D.O)MEUcore without burnable poison.

IN-02 (without burnable poison) EX-01 (without burnable poison)

position flow rate

(1/hr)

reactivity

(xlO~32Ak/k)position flow rate

(1/hr)

reactivity

(xlO~3ZAk/k)

Innerflowchannel(No.A)

middleflowchannel(No.B)

outerflowchannel(No.C)

50.1100.1200.2300.3400.5

50.1100.2200.3300.4400.6

50.099.9199.8299.8399.7

- 0.52- 1.50- 2.48- 3.54- 4.30

- 8.04-14.13-21.77-26.59-31.23

- 4.93- 9.18-14.51-20.22-23.03

innerflowchannel(No.D)

middleflowchannel(No.E)

outerflowchannel(No.F)

50.0100.0199.9299.9399.8

49.999.8199.6299.4399.1

49.999.9

199.7299.5399.3

- 3.56- 6.63-11.15-15.10-18.44

- 9.23-13.57-19.78-25.31-30.99

- 2.42- 5.69- 7.47- 8.29-10.56

Table 6. Void reactivity for the flow rate in C38R(BK D~0)MEUcore with burnable poison.

IN(B)-02

position

innerflowchannel(No. A)

middleflowchannel(No.B)

outerflowchannel(No.C)

(with burnable poison)

flow rate

(1/hr)

50.6100.7201.5302.2402.9

50.4100.7201.5302.5402.9

50.3100.7201.4302.1402.9

reactivity

(xlO~3%Ak/k)

- 0.36- 1.85- 1.21- 2.30- 3.14

- 6.97-11.66-17.08-22.36-25.42

- 5.23- 8.36-12.79-16.04-19.10

EX(B)-01

position

innerflowchannel(No.D)

middleflowchannel(No.E)

outerflowchannel(NcF)

(with burnable

flow rate

(1/hr)

50.4100.8201.5302.3403.0

50.4100.7201.4302.1402.8

50.4100.7201.4302.2403.0

poison)

reactivity

(xl0~3ZAk/k)

- 3.49- 6.43- 7.97-12.34-14.09

- 3.98- 7.79-12.87-18.04-22.79

- 3.58- 3.20- 7.36- 9.86-10.56

Page 11: COHP-821155—6 DE83 007724 KUCA CRITICAL EXPERIMENTS

• 650mm -'600mm-

(a)

175 mm2.09 mm

*—3i 53mm] 3,8mm

(b) JLSmm1mm

(C)

(a) : fuel plate

(b) : side-plate containing no burnable-poison

inner fuel element : L • 59.34 mm

outer fuel element : L » 67.41 mm

(c) : side-plate containing burnable-poison

inner fuel element : L » 59.40 mm, L • 47.1 mm

outer fuel element : L - 67.00 mm, L - 54.7 mm

Fig. 3. Illustration of the fuel plate and side-plates.

Page 12: COHP-821155—6 DE83 007724 KUCA CRITICAL EXPERIMENTS

Tig. 1. View of the heavy water tank for a single-core.

S d t - P t o l i '

Spoct lor Central Rods

O n t o lslonl

Hook

.Summing

Fuel Efcmtni

Fig. 2. View of the assembled fuel elements.

Page 13: COHP-821155—6 DE83 007724 KUCA CRITICAL EXPERIMENTS

FC2

UIC5

FC1

OjO tank (OjO reflector)

UIC6

IN-01 - IN-O6EX-01 - EX-12Cl - C3S4 - S6FC1 - FC3UICA - UIC6

Inner fuel elements (containing no burnable-poison)Outer fuel elements (containing no burnable-poison)Control.rodsSafety rodsFission chambersUncompensated ionization chambers

EX-01 - EX-12 contain 17 fuel plates.IN-01,-02,-05,-06 contain 10 fuel plates.IN-03 - IN-04 contains 9 fuel plates.

Total 262 plates

Fig. 4. C38R(BK D.0)MEU core configuration using the side-plateswith 3.8 mm pitch.

Page 14: COHP-821155—6 DE83 007724 KUCA CRITICAL EXPERIMENTS

i)-0MN(B)-06: Imar futl •Itimnn (containing burnobli poison)X-pt-06,08-12 : OuHr full t l w w n { • , )Uf-p7 : Outir futl tlimwus [containing no buraN* potion)

C3 : Gnirol rods6 S S &g iSSSR.&.rA

O : Acrylic void tub*©i,2A4.®558€,7,8: nt l l lon ol gold win. . o-i '• • • (lit* lop of fud plot*)

» i-o '• ' > |lb« niddlt of ftal plot*)— — p : • ( (44mni baloa lt» middl* of full pkM)

Fig. 5. Positions of wire irradiations in the C38R(BK D2O)MEUcore with an acrylic void tube at the center.

Page 15: COHP-821155—6 DE83 007724 KUCA CRITICAL EXPERIMENTS

1N(B)-OI-IN(B)-06: Iimr fuel *l«Mnti (cortolnnj burnabli poison)EX-03.06.09.12 : OuMr fwl tltiMffli I » » 1O U T | ^ (omoHng »tunrabto poiton)d - « < U O i ' " : Control ro<US4-S6 : Sohty mtoN : Nwtnn souu |*m-Bt 2CI)®9,10.11 : ftxiiiom of gold win with and without cadmium

Fig. 6. Positions of wire irradiations in the C38R(BK D2O)MEUcore without void tube at the center.

Page 16: COHP-821155—6 DE83 007724 KUCA CRITICAL EXPERIMENTS

IIH I 2 «1165 111

200 225

RSTMKC H O I T t f CENTER OF TtC CORE, ca

Fig. 7. Horizontal flux distributions in the C38R(BKcore with an acrylic void tube at the center.

I 4

Fig. 8. Horizontal flux distributions atD20 reflector in the C38R(BK D2O)MEU core

with an acrylic void tube at the center.

«ttM petition o in Fig.5

rtkteptoi*, INtBKMc IMBHB, INtBKB, IMBhOI,

I3 1

°0.0 5.6 11.2 168 22.4 w

1.1 B7 113 17.9 235DISTANCE, cm

Fig. 9. Horizontal flux distributionsalong the inner circular direction ofinner fuel region in the C38R(BK D.O)MEU core with an acrylic void tube atthe center.

Page 17: COHP-821155—6 DE83 007724 KUCA CRITICAL EXPERIMENTS

I.I10.1

11.2202

21.3303

31.4DISTANCE

4044I.S

, em

505SI.6

6066L7

70771.8

Fig. 10. Horizontal flux distributions along the outercircular direction of outer fuel region in the C38R(BKD70)MEU core withan acrylic void tube at the center.

A f l 1 ' • I I I I I I I T l l

° 0 7 5 0 20 30 40 50 60 70 725 80 90 95 NO °DISTANCE FROM TKaFFACE OF DC 6RID PLATE, o»

Fig. 11. Vertical flux distributions in the heavy-waterreflector of the C38R(BK D20)MEU core with an acrylic voidtube at the center.

Page 18: COHP-821155—6 DE83 007724 KUCA CRITICAL EXPERIMENTS

-4

*2

I

7 O * «• Imtr M l tim (toM« IWBI-05 rt -061I A k M MMr (Ml ragM ( M « M I 0UT-07 one) £X-0a)• 0 k l k u i l H I ngm (MMn EX-OI on* -02)(*-t mnmmt • «• n»Mnt i M H fl»SI

fuel plom

full imM

75 10 20 30 40 50 60 T0TZ5DISTANCE FROM Tl€ SURFACE OFTHE GRID PLATE, em

ED

Fig. 12. Vertical flux distributions between side-platesin the C38F(BK D20)MEU core with an acrylic void tubeat the cencer.

1»"2

7.5 10

I v m me conr m 9m anU k k t a M i M CN(ai-OC)

• • » w fM otmmntOUT-CT)

20 30 40 SO 60 TO 725DISTANCE FIOM THESURSCEOF THE GRID PLATE,cm

80

3 |

Fig. 13. Vertical flux distributions along center axisof the fuel element in the C38R(BK D O)MEU core withan acrylic void tube at the center.

Page 19: COHP-821155—6 DE83 007724 KUCA CRITICAL EXPERIMENTS

.10

i

(0 0 m ftm war d t» catIU laO^mt» O h Ma M f h*l •!•••« (CWMI

m Da tMliltm daaiilaFlf.6 i

10 C-

II

"0 15 10 20 30 40 SO 6 0 7 0 7 2 5 8 0DISTANCE FROM T>£ SURFACE Of THE GRID P U T E , era

Fig. 14. Vertical flux distributions in the C38R(BK D.O)MEUcore without void at the center.

i

15

° 0 75 10 S> 30 40 50 60 70 72b 80DSTAtCE FJOI THE SURFACE CfTHE GRD PLATE, cm

Fig. 15. Thermal-neutron flux distributions in theC38R(BK D20)MEU core without void at the center.

Page 20: COHP-821155—6 DE83 007724 KUCA CRITICAL EXPERIMENTS

in

O

8o

a>

oCD

12

10

8 -

-2

-6

-8

\

\

no void at the center Island

acrylic void pipe at the center Island

-1020 30 50 60 70

Core temperature,*C

Fig. 16. Temperature reactivity coefficients.

Page 21: COHP-821155—6 DE83 007724 KUCA CRITICAL EXPERIMENTS

FC2

UIC5

FC1

D20 tank (D2O reflector)

FC3

IN-01 - IN-06EX-01 - EX-12Cl - C3S4 - S6FC1 - FC3UIC4 - UIC600000

UIC6

Inner fuel elements (containing no burnable-poison)Outer fuel elements (containing no burnable-poison)Control rodsSafety rodsFission chambersUncompensated ionization chambersStainless tubes

EX-01 - EX-12 contain 17 fuel plates.IN-01 - IN-05 contain 10 fuel plates.IN-06 contains 9 fuel plates.

Total 263 platesThe 10th, 11th and 12th plates of IN-05 from the outside have beenremoved.

Fig. 17. C38R(BK D-0)MEU core configuration without burnable-poisonfor the measurement of void reactivity effects.

Page 22: COHP-821155—6 DE83 007724 KUCA CRITICAL EXPERIMENTS

FC2

UIC5

FC1

FC3

UIC4

IN-01,IN-03 - IN-06IN(B)-02EX-01 - EX-03,EX-05 - EX-12EX(B)-04Cl - C3S4 - S6FC1 - FC3UIC4 - UIC6

UIC6

Inner fuel elements (containing no burnable-poison)Inner fuel element (containing burnable-poison)

Outer fuel elements (containing no burnable-poison)Outer fuel elements (containing burnable-poison)Control rodsSafety rodsFission chambersUncompensated ionization chambers

EX-01 - EX-12 contain 17 fuel plates.IN-03 - IN-05 contain 11 fuel plates.IN-01, IN(B)-02 and IN-06 contain 10 fuel plates.

Total 267 plates

Fig. 18. C38R(BK D_0)MEU core configuration with burnable-poison-for the measurement of void reactivity effects.

Page 23: COHP-821155—6 DE83 007724 KUCA CRITICAL EXPERIMENTS

Outer flow channel No.F

Middle flow channel No.E

Inner flow channel No.D

Outer flow channel No.C

Middle flow channel No.B

Inner flow channel No.A

IN-02or IN(B)-02

Gas flow position : the center of the flow channel( A symbol • shows the position of nozzle )

N, gas outlet nozzle : the height of 1 cm from the bottom offuel plate

The side plates of EX(B)-04 and IN(B)-02 contain boron burnable-poison.

Fig. 19. Position of N_ gas outlet nozzle.

Page 24: COHP-821155—6 DE83 007724 KUCA CRITICAL EXPERIMENTS

10

15

20

25

30

35

REACTIVITY (X10~3ZAk/k)

FLOW RATE (L/HR)50 100 200 300 400

( ( (—*

REACTIVITY (X10"3Z Ak/k)

FLOW RATE (L/HR)200 300 400

A(b)

IN-02

OA

a

Inner flow channelMiddle flow channelOucer flow channel

IN(B)-02Inner flow channelMiddle flow channelOuter flow channel

No.A(b)No.B(b)No.C(b)

25

30

35

EX-04O: Inner flow channel No.DA! Middle flow channel No.Ea : Oucer flow channel No.F

. EX(B)-04• : Inner flow channel No.D(b)A: Middle flow channel No.E(b)• : Outer flow channel No.F(b)

Fig. 20. Comparison between voidreactivity in the core with andwithout burnable-poison.

Fig. 2i, Comparison between voidreactivity in the core with andwithout burnable-poison.

Page 25: COHP-821155—6 DE83 007724 KUCA CRITICAL EXPERIMENTS

References

1. K. Kanda and Y. Nakagome ed., "Research Reactor Using Medium-EnrichedUranium," KURRI-TR-K2 (1979).

2. T. Shibata, "Construction of a High Flux Research Reactor and Conversionof Kyoto University Reactor KUR to a TRIGA Type Pulsed Reactor," IAEA-214(1978) 183.

3. T. Shibata and K. Kanda, "ANL-KURRI Joint Study on the Use of ReducedEnrichment Fuel in KUHFR —Phase A Report —," (February 15, 1979).

4. A. Travelli, D. Stahl and T. Shibata, "The U.S. RERTR Program, Its FuelDevelopment Activities, and Application in the KUHFR," ANS Trans., _3j6(1981) 92.

5. K. Kanda, K. Kobayashi, M. Hayashi and T. Shibata, "Reactor PhysicsExperiment Using Kyoto University Critical Assembly," J. At. Energy Soc.Japan, ̂ (1979) 557, in Japanese.

6. T. Shibata and A. Travelli, "ANL-KURRI Joint Study on the Use of ReducedEnrichment Fuel in KUHFR — Status Report on Phase B —," (december 12,1980).

7. K. Kanda, S. Shiroya, M. Hayashi, Y. Nakagome and T. Shibata, "KUCACritical Experiments Using MEU Fuel", IAEA-SR-77/30 (1981)

8. K. Kanda, S. Shiroya, M. Hayashi, K. Kobayashi, Y. Nakagome andT.Shibata, "KUCA Critical Experiments Using Medium Enriched UraniumFuel", Annu. Rep. Reactor Inst. Kyoto Univ., 15_ (1982).

9. S. Shiroya, H. Fukui, Y. Senda, M. Hayashi and K. Kobayashi,"Meas" rements of Neutron Flux Distributions in a Medium Enriched UraniumCore", Annu. Rep. Reactor Inst. Kyoto Univ., _L5_ (1982).

10. M. Hayashi and S. Shiroya, "Few-Group Constants for the HEU and MEUcores in the KUCA," Aruiu. Rep. Res. Reactor Inst. Kyoto Univ., \U_ (1981).