ML20003H154
| ML20003H154 | |
| Person / Time | |
|---|---|
| Site: | 07002932 |
| Issue date: | 04/03/1981 |
| From: | Gary R TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC) |
| To: | Ketzlach N NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| References | |
| 18880, NUDOCS 8105050234 | |
| Download: ML20003H154 (13) | |
Text
{{#Wiki_filter:- 'f r[o ~t> Q)b ~ s TEXAS UTILITIES GENEIMTING COMPANY 2tmit IlltY AN Tt 3% F:H. In \\ LL \\% "I IW sw '.320t April 3,1981 ,,,c.jjj,..[,,,,, ^ g*6 q /A 6' cccxam g {,;* m - v.nc m ~ S EA APR 171981 > Mr. Norman Ketzlach o R t Division of Fuel Cycle and s I l. Material Safety ng[fk., 5 j U. S. Nuclear Regulatory Commis DccKErctat /d .c4 1-Washington, D.C. 20555 / ow .:t Jg \\&
Dear Mr. Ketzlach:
Your letter dated January 14, 1981, requested additional information in order to complete the review of our applica-tion dated July 10, 1980, for authorization for receipt, possession, storage, inspection and preparation for trans-port of special nuclear tr.aterial required for the operation of the Comanche Peak Steam Electric Station Unit 1. Eight (8) copies of the responses to your comments concerning the required additional information are enclosed for your evaluation. Your prompt completion of the application review will be appreciated. Respectfully, R. J. Gary RJG:kp Enclosure (s) g
- y(o 4= g 3 s
e i 9 3, N js o I I
- g. ;.>c. jh I
< p a n o-orc 9 & c o 13S30 8105050234
RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION ON TEXAS UTILITIES GENERATING COMPANY LICENSE APPLICATION FOR FUEL STORAGE ONLY AT UNIT 1. COMANCHE PEAK STEAM ELECTRIC STATION Section 1.1.2 Comment (1): Specify the pellet diameter and fuel rod pitch in an assembly.
Response
The average outside diameter of the slightly enriched uranium dioxide pellets is 0.3225 inches. The fuel rod pitch in a fuel assembly is 0.496 inches. Comment (2): Confirm 3.1% U235 is the maximum enrichment in a fuel assembly.
Response
Disregarding the nominal enrichment variations produced during the U. S. Department of Energy's enriching process, the maximum fuel assembly enrichment to be stored under the Comanche Peak Steam Electric Station Unit 1 Special Nuclear Material License is 3.1 weight percent (w/o) U-235.. The highest anticipated enrichment assumed for nuclear criticality safety analyses is 3.5 w/o U-235. 13SSO 1
Section 1.2.2 Comment (1): Specify the minimum spacings between fuel handling (e.g., carrier unloading, assembly inspection) and fuel assembly storage areas.
Response
The m' inum spacing between the nearest fuel storage racks and the new fuel receipt and inspection area is a horizontal distance of approximately 12 feet. It should be noted, however, that the operating level over the new fuel storage racks is at elevation 860' whereas the operating level for the new fuel receipt and inspection area is at elevation 841'. The attached Figure 1 shows the Fuel Building location of the fuel storage areas and the new fuel receipt and inspection area. Conment (2): Confirm preoperational testing for necessary fuel handlinc and support systems will be completed prior to receipt of unirradiated fuel. All equipment should be inspected and tested for safe operation prior to use in fuel handling activities.
Response
Prior to receipt of new fuel, all required fuel handling equipment and storage f acilities will be inspected and tested to ensure safe operation during fuel handling activities. 1 k 2
Section 1.2.4 ~ Comment (1): Confirm all construction related to fire protection of the fuel handling and storage areas is completed prior to receipt of unirradiated fuel.
Response
APCSB 9.5-1, Appendi:. A, requires that the fire protection program (plans, -personnel and equip-ment) for buildings storing new reactor fuel.and for adjacent fire. zones which could affect the fuel storage zone to be fully operational before fuel is received at the site. Therefore, the Fire Protection Programs for the Fuel Handling Building will be in effect and the suppression systems erational prior to receipt of fuel on the site c s as stated in the Comanche Peak Steam Electric Station Final Safety Analysis Report (CPSES FSAR) Section 9.5. 3
Section 2.1.2 Comment (1): Identify the responsibility for administration controls and for the development and approval requirements to ensure safety for all fuel handling and storage operations. Specify the approval requirements. Respons e: Administrative controls which govern the safe handling and storage of fuel will be the respon-sibility of the Engineering Superintendent. Those s procedures which control the safe handling of fuel will be approved by the Station Operations Review Committee (SORC). The function of the SORC is described in Section 13.4.1 of the CPSES FSAR. 4 Comment (2): Confirm all fuel handling operations will be performed in accordance with approved written procedures.
Response
The manipulation of the new fuel assemblies will be performed by CPSES Operations personnel trained in proper fuel handling techniques and, in addition, will be done in accordance with approved written fuel handling procedures containing provisions to assure that all fuel assemblies are handled correctly. 4 Comment (3): Specify the precautions taken to meet ALARA.
Response
Radiation and contamination monitoring will be performed prior to the initial handling and storage of new fuel. This practice should identify any possible radiation hazards associated with external contamination of new fuel assemblies and allow proper planning for ALARA controls deemed necessary by Chem-istry and Health Physics personnel. (Reference Section 2.1, CPSES Application for Special Nuclear Material License) Due to the fact that the fuel will be unirradiated, there will be no significant radiation hazard associated with the low level radioactivity of the fuel its elf. The handling and storage of the fuel, as outlined in the CTSES Application for Special Nuclear Materials License, will be sufficient to maintain radiation exposures ALARA. t 4
Section 2.2 Comment (1): Confirm there will be no more than one fuel assembly outside the shipping container or storage rack at any one time.
Response
In order to prevent accidental criticality, only one new fuel assembly will be allowed to be re-x moved from a shipping container or an approved storage location at any one time, e Comment (2): Describe the design of the new and spent fuel storage racks. Include sketches in support of the description.
Response
The new fuel storage racks (Figure 2) are composed of individual vertical cells fastened together to form a module which can be firmly bolted to anchors in the floor of the new fuel storage pit. The new fuel storage racks are designed to include storage for two-thirds core " a center-to-center spacing of 21 inches. The design of the fuel storage rack assembly is such that it is impossible to insert the new fuel assemblies in other than prescribed locations. All surfaces that come into contact with the fuel assemblies are made of annealed austenitic stainless steel. The fuel storage racks are designed to withstand normal operating loads as well as Safe Shutdown Earthquake (SSE) and Operating Basis Earthquake (OBE) seismic. loads meeting ANS Safety Class 3 and ASME B&PV Code 'Section III, Appendix XVII requirements. The fuel storage racks are also designed to meet the seismic Category I. requirements of NRC Legulatory Guide 1.29, Revision 2, February 1976. The fuel storage racks can withstand an uplif t force equal to the 5000 lb. uplift force of the fuel handling bridge crane. The spent fr?1 storage racks (Figure 3) are composed of individual vertical cells fastened together at a 16 inch center-to-ceater spacing to form a module which is firmly bolted to anchors in the floor of the spent fuel pool. Space between storage cells is blocked to prevent insercion of fuel. All surfaces that come into contact with fuel assemblies are made of annealed austenitic stainless steel. The spent fuel storage racks are designed to withstand shipping, handling, normal operrting loads (dead loads of fuel assemblies), as well as SSE loads. These racks meet ANS Safety Class 3 and ASME B&PV Code, Section III, Appendix XVII requirements. The spent fuel storage racks are also designed to meet the seismic Category 1 requirements of Reg. Guide 1.29 Revision 2, February 1976. The rasks can with-stand an uplift force equal to the uplift force of the spent fuel pool bridge hoist. 5
Comment (3): Provide the results of the nrclear criticality safety analyses, the method of analysis used, and the assumptions made in the analysis (e.g., degrees of water moderation, dropping of a crane loading on top of the rack).
Response
New fuel is stored in 21 inch center-to-center racks in the new fuel storage facility with no water present. These racks are designed to prevent accidental critical-ity even if unborated water is present. The design of the new fuel storage racks is such that the effective multiplication factor (keff) does not exceed 0.98 with fuel of the highest anticipated enrichment in place, assuming optimum moderation (under dry or flooded con-ditions). For the normally dry condition, keff does not exceed 0.98 with fuel of the highest anticipated enrich-ment in place assuming possible sources of moderation 4 such as those that could arise du' ring fire fighting operations (such as foam or water mist). Consideration is given to the inherent neutron absorbing effect of the materials of construction. The new fuel storage racks have adequate energy absorp-tion capabilities to withstand the impact of a dropped fuel assembly from the maximum lift height of the fuel 'andling bridge crane. An analysis was done using a standard 17 x 17 fuel assembly with the handling tool and a total mass of 2000 lb. falling from a height of 3.5 feet (without damping or energy dissipation) on to the top of a fuel cell. The analysis results show that the fuel cell deforms in compression and shortens in length. The accident would not result in an unsafe geometric spacing of fuel assemblies. Cranes capable of carrying loads heavier than a fuel assembly will be prevented by interlocks or administrative controls, or both, from traveling cver the new fuel storage area when new fuel is sto;ed in the new fuel storage racks. Unborated water of 1.0 gm/cm is assumed in the analysis of new fuel stored in the spent fuel pool racks. Over the range of water densities of interest (corresponding of 60 F through 212 F), full density water is a conservative assumption since a decrease in water density will cause keff to decrease. Boiling is not permitted to occur under any circumstances. The design basis for the wet fuel storage criticality analysis is that there is a 95% confidence level that the keff of the fuel storage array will be less than 0.95 per ANSI Standard N18.2-1973. The results of the analysis for an infinite array of 17 : 7 assemblies en-ciched to 3.5 w/o U-235 show that a 14.0 inch center-to-center rack spacing corresponds to at least 95% of the time keff will not exceed 0.95 at a 95% confidence level, t
The spent fuel storage racks have adequate energy absorption capabilities to withstand the impact of a dropped fuel assembly from the maximum lif t height of the fuel handling bridge crane. In the analysis for both the new tuel storage racks and the spent fuel storage racks, the fuel assemblies are assumed to be in their most reactive condition,- namely fresh or undepleted and with no control rods or removable neutron absorbers present. Assemblies can not be closer together than the design separation provided by the storage racks.. The mechanical integrity of the fuel assembly is assumed. Verification that the design criteria for fuel storage are met is achieved through the use of standard Westinghouse Electric Corp-oration design methods such as the LEOPARD and PDQ codes. Comment (4): Confirm all degrees of credible interspersed moderation (e.g., from sprinklers) have been considered in the nuclear criticality safety evaluation.
Response
Nuclear criticality safety evaluations for fuel ctored in 21 inch center-to-center racks were performed assuming fuel of the highest anticipated enrichment in place and optimum moderation conditions (such as foam or water mist arising from fire fighting operations) existing under dry storage conditions. The results of the evaluations showed that keff does not exceed 0.98. Optimummoderationconditionsfrominterspersegmoderators require a density of approximately 0.1 gram /cm. Achieving moderator densities in this range is not credible. As a point of referenge, the water density of a heavy rainstorm is 0.00014 gm/cm ; steam at 1 ATM and 212 F has a density 3 of 0.0006 gm/cm ; firefightingsprinklers, foams,andsprays have densities of 0.001 gm/cm ; a stream from a water hose that has diverged from 1" to 10" has a density of 0.01 3 gm/cm. Thus, achieving a density of 0.1 gm/cm over a significant rack volume has an extremely low probability of occurrence. The levels of low-density moderation needed to compromise the safety of the fuel storage arra'y are not achievable by accident. Comment (5): Provide the administrative controls to ensure " checkerboard" loading of new fuel in the spent fuel pool racks. What is to prevent the inadvertent insertion of an assembly in the open storage cells of the array? 7
Response
A loading pattern will be developed for the storage of new fuel in the spent fuel pool. The loading pattern will identify each fuel. assembly's assigned storage location and will arrange the fuel in an " expanded checkerboard" array. This " expanded checkerboard" array is described in more detail in the response to Comment (6) below. Periodic x ^ loading verification checks will be performed during new fuel storage operations in the spent fuel pool ~ with a final verification to be performed af ter all new fuel assemblies have been loaded into their assigned storage locations. The inadvertent insertion o* a new fuel assembly into one of the dry open storage cells of the " expanded checker-board" array will have no adverse consequences since keff for this dry storage condition will remain less than 0.98. Only for the most optimum moderation conditions (i.e., fire fighting operations) could the keff exceed 0.98. If during any of the periodic loading checks a fuel assembly is found to be out of its assigned location, it vill be promptly returned to its correct storage location. Comment (6): Provide justification for the assumption the " checker-board" array of fuel assemblies has a multiplication factor (keff) no greater than that for the array of assemblies in the new fuel storage areas. The edge-to edge spacing between some assemblies in the " checkerboard" array are closer than that between those in the new fuel storage racks. Considerat' ion should be given to the optimum credible water noderation within and between fuel assemblies.
Response
Dry storage of new fuel assemblies in the spent fuel pool racks will be in an " expanded checkerboard" array such that an open storage cell exists in the 8 adjacent cells surround-ing each assembly. Therefore, no two assemblies will be closer than the 21 inch center-to-center spacing of the new fuel storage racks. This more conservative loading pattern for new fuel storage in the spent fuel racks will result in a 32 inch center-to-center spacing between fuel assemblies. For the flooded condition with unbarated water present and assuming new fuel of the highest anticipated enrichment in place, the ef fective multiplication factor (kef f) does not exceed 0.95. For the dry storage condition, keff does not exceed 0.98 with fuel of the highest anticipated enrichment in place assuming possible sources of optimum moderation arising from fire fighting operations. The plastic covering around each assembly will be opened at the bottom to allow water drainage should flooding and then draining of the fuel storage occur, thereby eliminating any possibility of non-uniform radial moderator distribution. Inadvertent insertion of an assembly in an open cell of the array will be precluded 8
by the use of previously developed loading patterns and periodic loading verification checks. (see Response to Comment 5 above) i 9 - ~.--
Figure 1. CPSES Fuel Building Floor Plan s o c{, o Le 8 l'1 d r E en
- ) e-4 4.a <
d. -C-Y o ses c EJ i 5 g" e e o au / I 4 h 'e .,e- ~.1 n-BE ,\\ { 5 E- $ 3' =I e x=- 6\\ ->N li,Y;,q!Il.i !
- e. "
li.i5 c g x. s.- 'A c '14 s' E I r i h5 II 1 =, 5 . i. ,3 p n e a, , j MM 9 4, S- /\\\\ s,w; b -/$ { %..,r==% } U f$1 i p/ l. u b l Z'@? l $n.12 4 1 *., ,4 __1 1; / x, c. ? V i p -/ 1., J e. J..Qkleiy M; e=: ~ ~ ~ c~ 3 .n... t J. ; 2 v yIm.f.. f}1 {jf i 3 1 m \\...... --tp( Jill q 1]L a ~ j i !.l. 4 j n 3
- .0' !;
g i s,. r @!Mi li D_.fMI ;'n[i.5;i,[xr y sti i l {g,. f _:
- s. ~
5 . 1 Pl 4M
- i. ime T e 1
>e: w ~~ 'E/ {4 g 11 i k:I ('s IA 4 g P. Li .a E g11 " c. -, i I
- {3 Id!,f
} W d.c,An\\.\\<-)\\."AO}:l.;,LiRd{g '\\'g W g \\ .%R b .t.',i V i '.. g 1 { t' 8 \\ j (g -N i s ) f g. s, .pWM
- .n,n,
, I, te l ' (' j n. m r .$,_{--- ~ SL h { -- g"k s } 5 2, .h p.. ~J utuI [ k i k b ! 1 3 t s tl .A s p i ,/ g i r. t L H. A{cd;:. 'h.% W w-7ig y4 7i e. p ,;, g.. er o* d \\ ~ ' H d,.1.!ti. s \\ i ikE gl L-1i (1 =~ 10
Figure 2. New Fuel Storage Racks -4 Y .v $ s .n-zi we .. =g__. a __. / _ eel-h n A-8 E ] g A _v. -r-8 2:__-?w .i . -A 1 r% -g. vo / i et 8 c' t-a ., oi 9; i I "mii ',(-jdLQ_t.__*N"_@_Q_W_p_Q_Q;. e W L
- t i
i.g1-$ Le _ M] q' ,,,iii..l 3 7 i,,i_ i-s!_ q L,,-y "#- M u 7. 1 {t. ! i s
- '."$.t
- .@':-.. 45,; ',, l.
t_ Ih._h. 1_*t 1_- q- -e t d a *
- .,. ;-{,h._rn., h.j:__[h. :_S M m
H , v.yd. u. > _.. .,r:- ~. ' rrl a! = m,J l l r: i j 9.e .i r i< 1 i i li i! I i yf [6 lI l ll l I .-,j i, -p.-_y-e-gg ~; a e.- .we-e u O U$ 0 0 0 iA 7 O E b O O O b b W is a0 Og Da 60 06 66 66 a$ 60 6 6, 6, 6 04 06
- 6. 0,
.f g~s; s* 4 I OO O OO QO O O, O O OO .f 8-O O OO OO Q OO O O OO
- E C O O
b O O E{r-O d,- h. g f.1 G - Ob b b O O .n-I -: n ..:.. ~ ...= y n e--- .D.9 .E.O E 9.E ' 11
Figure 3. Typical Spent Fue Rack 4 16 hos I 1 ( p /' p /> !?'- - i \\9 k'fl pk i% y i / O . ;\\y y/ ,/ s
- s x
m e[ '%/% &/k)_O /x &d l l 1SS30 12 l}}