ML19254B419
| ML19254B419 | |
| Person / Time | |
|---|---|
| Issue date: | 09/20/1979 |
| From: | Eisenhut D Office of Nuclear Reactor Regulation |
| To: | Gridley R GENERAL ELECTRIC CO. |
| Shared Package | |
| ML19254B417 | List: |
| References | |
| MFN-210-78, NUDOCS 7909270492 | |
| Download: ML19254B419 (6) | |
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UNITED STATES NUCLEAR REGULATORY COMMISSION 3
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WASHINGTON, D. C. 205M p
September 20, 1978 General Electric Company l
Attention:
R. L. Gridley, Manager
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Operating Plant Licensing 175 Curtner Avenue San Jose, California 95125
SUBJECT:
GENERAL ELECTRIC COMPANY LETTER DATED MAY 22, 1978 FROM R. L. GRIDLEY TO D. G. EISENHUT ON " REACTIVITY LIMITATION ON GE BWR FUEL IN SPENT FUEL STORAGE RACKS" Gentleman:
We have reviewed your letter of May 22, 1978, regarding the reactivity limitations for fuel which is to be p' aced in spent fuel storage racks.
You state that reliance on the analyses of keff in the spent fuel pool is in itself sufficient and that it should be used rather than the current method of limiting the axial fuel loading to insure subcriticality for fuel storage.
We generally agree with your recomendation. However, we find it necessary to use the U235 axial fuel load limit method in the interim because sufficient analyses have not been provided to demonstrate the uncertainties in the calculations.
If these analyses were pro-vided and justified and the technical specifications included a specific reference to the fuel assembly design which was analyzed, this aporoach would be acceptable.
Currently, licensees have elected to use the fuel loading limit method.
This method, which is based on the present degree of optinization of LWR fuel assemblies, does not require detailed analysis of uncertainties.
It can also be used for different fuel assembly designs with no additional analysis other than demonstrating that the fuel loading is not in excess of that specified.
If you have any further questions regarding this subject, we would be happy to discuss them with you. \\
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. Eisenhut, Assistant Director Systems and Projects Division of Operating Reactors
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GENERALh ELECTRIC
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ENGlNEERING GENERAL ELECTRIC COMPANY.175 CURTNER AVE., SAN JOSE. CALIFORNIA 95125 DIVISION
'R ECE;"m July 10, 1978 JUL 131978 NSD-78-12 6 n.o.eaucou James F. Mallay Chair =an, AS-50 Co=mittee Babcock and Wilcox Co.
P.O. Box 1260 Lynchburg, VA 24505
Dear Mr. Mallay:
Subj ect :
Request for Change in Section 5.1.12.1 of A=erican National Standard N210-1976/ANS-57.2 Section 5.1.12.1 of ANS N210 states, in part, that the design of the spent fuel storage racks "shall be based on the maximum enrichnent and fissile isotopic content of fuel to be cycled in the plant...".
This requirment is apparently based on data on PWR fuel (with unifor:
U-235 distribution) in which the concentration of U-235 is a fair indicator of reactivity in the fuel storage arra;. This requirement is not appropriate for GE BWR fuel which contains the neutron absorber gadolinia in non-uniform distributien as well as U-235 in non-unif orm distribution. Because of this, there is not a simple correlation between the maximum enrichment of U-235 and the reactivity of the fuel in the storage rack. Therefore, the enrich =ent of U-235 cannot be used to directly measure the reactivity of GE BWR fuel in storage.
The NRC has used section 5.1.12.1 as a basis to impose new technical specification requirements for spent fuel storage on utilities who operate GE BWR's.
The new requirements contained in the technical specifications i= pose a limit on the weight of U-235 per unit length of fuel bundle, which is the same as a U-235 enrichment limit.
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July 10, 1978 Page two General Electric's arguement against the use of an enrichment limit is based on the fact that any limitation on U-235 enrichment must consider Gadolinia or be inconsistent with the acceptance of Gadolinia as a means of reactivity control in the reactor. Such a limitation would also be unjustifiably overly-conservative if appli2d to fuel at zero or low exposure. The only technically correct way to take both U-235, Gadolinia and other reactivity contributors into account for OE BWR fuel is by use of the parameter k..
The limitation on fuel oundle k. (k. of the fuel bundle in the reactor core geometry at 20 C) has historically and correctly been applied at the e::posure that maximizes k. to assure that the k gg limit imposed on the e
spent fuel storage atray is met.
There is a direct correlation between fuel bundle k. and fuel storage array keff.
Each FSAR or specific Jeload licensing submittal contains data on fuel bundle k.'s as a function of expousre and the k. that results in the limiting fuel storage kef f (including biases and uncertainties) is known f rom extensive calculations. Hence, by simple co=parison of actual calculated k.'s to the limiting k,
compliance with the specified kef f limit on the spent fuel storage array can be assured.
The Ibnit on U-235 enrichment is unnecessary and unjustified with respect to GE BWR fuel. Therefore, we request that the statement in which this limit appears be modified such that it includes a statement on fuel bundle reactivity limits for BWR's.
A suggested wording of this statement is "The design shall be based on the maximum enrichment and fissile isotopic content of fuel to be cycled in the plant for PWR's or based on the maximum k value of fuel to be cycled in the plant for BWR's."
Should you require any additional information or clarification on this
=atter, please contact the undersigned.
Very truly yours,
.C.>dI!a= C7&
C. J. Paone Core & Fuel Systems Design Mail Code 765 - Ext. 56160 1m cc:
R. O. 3rugge e' W. H. D'Ardenne D. M. Dawson C. C. Herrington L. L. Lantz D. H. Morley S.
Nabow L. A. Steinert E. P. Stroupe R. C. Stirn 1048 341
Dmac Powien Co3mm STEA31 1*ltOl#UCTION del'T.
GENEltAI. OFFICES mensoN E: AREA 704 P. o, sox sates 422 SOUTH CHURCH STREET 373 4ott C11AltLorrE, N. C. 2824'4, Ii May 22, 1979 i
o,eOC!\\rn SEP Ig1979 ci%,.,
s-Mr. L. A. Steinert General Electric Company (M/C 712) 175 Curtner Avenue San Jese, California 95125
Dear Leo:
By now, you should have received the notice concerning the next meeting of ANS 57.1/N208 Working Group in Boston, June 13-15.
The agenda for this meeting will include putting the final finishing touches on N208 by revising the section dealing with criticality and agreeing on boxing.
In addition, we will discuss and adopt a response to C. J. Paone's letter requesting relief from the criticality section, 5.1.12.1, of N210.
This will be done as an interpretation to N210 similar to the one in response to a Westinghouse question last year.
We will make every effort to make the criticality portion of N208 and the interpretation to N210 agree.
I believe that it is very important for G. E. to be represented at this meeting so that we do not inadvertently impose unwarranted restrictions on BWR design when we revise these standards.
Please make every effort to attend.
Very truly yours, S. E. Nabow, Chairman ANS 57.1 SEN:vr 1048 342
t BWR SYSTEMS ENGINEERING DEPARTMENT San Jose, California cc:
R.0. Brugoe g
0.M. Dawson B.E. Lawler D.H. Morley L.A. Steinert P.
van Diemen
,CFSD-79108 June 18,1979
,:a as.
1v. e w_
TO:
DISTRIBUTION
SUBJECT:
Revision to ANS 57.2/N210
REFERENCES:
1.
Letter from C.J. Paone to James F. Mallay, "Recuest for Chance in Section 5.1.12.1 of American National Standard N210; 1976/ANS-57.2", July 10,1978.
2.
ANS-57.7, " Design Criteria for an Indeoendent Scent Fuel Storage Installation (WATER POOL TYPE)", March 1979.
3.
Letter from S.E. Nabow to L.A. Steinert, "ANS 57.1/N208 Working Group Meeting",May 22, 1979.
Section 5.1.12.1 of ANS N210 states, in part, that the design of the scent fuel storage racks "shall be based on the maximum enrichment and fissile isotopic content of el to be cycled in the plant...".
On July 10, 1978 a letter was issued (g/ to J.F. Mallay, Chairman of the ANS-50 Committee requesting that an interpretation of paragraph 5.1.12.1 of N210 be made met in Boston June 13,14 and 15(ANS-50 Corrittee chaired by(S.E. Nabow for boiling water reactors. The 3), and the subject recuest I) was on the agenda for action.
The Committee met and discussed this item June 13 and via a conference call between S.E. Nabow and R.C. Stirn on June 13, the last details which were acceptable to both parties were worked out. Given below are the results of this discussion and changes or interpretation to N210 which address our re-quest.
The requested change to caragraoh 5.1.12.1 of ANS 57.2/N210 will be done as an interpretation to N210 similar to the one in response to a Westinghouse question last year. The comittee made every effort to make the criticality portions of ANS-57.7, ANS-57.1/N208, and the interpretation of N210 agree.
To meet this cbjective the requested interoretation will reference ANS 57.7(2) including some changes noted below:
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The ANS 57.2/N210 interpretation:
(1) will delete the last sentence of N210 p?ragraph 5.1.12.1 which recuired that the fuel storage racks be designed for the maximum enrichment fuel.
(2) will reference the criticality requirements as stated in Section 6.10 of ANS 57.7 along with the following changes:
(a) on page 6-41, paragraph 5.10.3 will be changed to read:
"Kc " Keff computed for the most reactive fuel at the most reactive exposure..."
(b) on page 6-42, paragraph 6.10.4.1 b) will be changed to read:
"the most reactive fuel assembly to be stored based on a minimum
. confirmed U-235 burnup..."
(c) on page 6-42, paragraph 6.10.4.2 will add burnable poison content to a list of design parameters to be considered.
6-43, paragraoh 6.10.4.4 will add "oresence of the remain-(d) on page ing amount of burnable poison in fuel assembly" (Note: This has already been added in March 1979 draft of ANS 57.7).
Based on the above interpretation of ANS 57.2/N210 and assuming that this interpretation gets implemented, our concerns stated in reference 1 have been adequately resolved by the ANS-50 comittee.
C.
R.C. Stirn, Manager Core & Fuel Systems Design MC 740, Ext. 56139 RCS:km
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