ML19345H474
| ML19345H474 | |
| Person / Time | |
|---|---|
| Site: | Zion File:ZionSolutions icon.png |
| Issue date: | 05/11/1981 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19345H472 | List: |
| References | |
| NUDOCS 8105200363 | |
| Download: ML19345H474 (7) | |
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NUCLEAR REGULATORY COMMISSION
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SAFETY. EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO. 64 TO FACILITY OPERATING LICENSE NO. DPR-3,9 AND AMENDMENT NO. 61 TO FACILITY OPERATING LICENSE NO. DPR-48 COMMONWEALTH EDISON C0f9ANY ZION STATION, UNITS 1 AND 2 DOCKET NOS. 50-295 AND 50-304
1.0 INTRODUCTION
By letter dated October 22, 1979 (Reference 1) the Commonwealth Edison Company (Licensee) requested changes to Operating License A for i on Station Units 1'and 2.
Nos. DPR-39 and DPR-48, Appendix, The purpose of the submittal is to revise the Zion Technic &L Specifications to increase the allowable LOCA peaking factor limit from 1.86 to 2.20 based on an ECCS reanalysis.
The reanalysis involves certain previously reviewed thermohydraulic model changes referred to as "UHI Technology," and changes t'o t'he input fuel stored energy.
In addition the licensee has performed an accumulator
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water volume sensitivity study.
Results are presented for the Large guillotine break with three discharge coefficients.
Also presented are the sensitivity resuLts for various ccmbinations cf UMI technology m e t h o d,s and for the accumulator water volume m
be 'oted that the licensee must con-study.
Finally, it should n
side-the impact of the interim recuirements for cladding swelling 1
a r. d ructure (Reference 2).
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2 2.0 FUEL S.TORED ENERGY CHANGES Th licensee proposed to remove the 65 degrees Fahrenheit pellet
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temperature modeling conservatism added to the average fuel temperatures calculated by PAD.
Thi_s has been previously approved by the staff and is therefore acceptable (Reference 3).
l 3.0 UHI TECHNOLOGY In analy:ing the large break LOCA, the applicant has proposed to use some of the-modeling techniques currently approved for ate
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in Westinghouse plants equipped with Upper Head Injection (UHI)
(Reference 4).
The following four changes were made to the SATAN VI computer program (Reference 5):
1.
ps'eudo-viscosity f,
2.
equation of state l
3.
modified drift flux 4.
elevation pressure change These changes were reviewed and approved for UHI plants in
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Reference 4.
None of th,e four changes is unique to UHI plants
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f and would be equally suitable to non-UHI plants.
We therefore find those SATAN modifications acceptable for the Zion large break analysis.
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The model approved in Reference 4 utilizes a s p li t' downcomer l
.This modeL was ccmpared to several er:erihental l
rcdaLi:ation.
results (Reference 5) and found accettable.
Since the exoeriments were net related to UHI, this model wculd also te ac:e: table fer r.cn-t"JI :Larts su:5 as !ien.
3 To account more realistically for the actual Westinghouse
-Looo ccr. figuration, the intact loop nodati:ation was split back to i
s eam generator.
Although this was not done for UHI plants, it is bekter representation for use with the split downcomer actually a and is therefore acceptable.
Addition of a containment node to better handle break flow slip is also acceptable.
A sensitivity l
l study to this change actually resulted in a slight increase in peak cladding temperature.
Several other non-substantive changes in SATAN not related to UHI technology are also acceptable.
4.0 ACCUMULATOR VOLUME SENSITIVITY This sensit'vity study is. consistent with t he requirements of i
Reference 6 and thus the analysis should be done wi,th higher water volume.
.5. 0 CLADDING SWELLING AND RUPTURE The NRC staff has been generically evaluating three materials models that are used in ECCS evaluations.
Those models predict cladding rupture temperature, cladding burst strain, and fuel
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assembly flow blockage.
We have (a) discussed our evaluation l
with vencors and ether industry representatives (Reference 7),
':) zu:Lished NUREG-0630,'" Cladding Swetting anc Rue:ure P.:cels for LOCA Analysis" (Reference 2), which ccaeluded that licensing cladding : dels
.e E, in general, ncn-c0nservative, and (c) re:;uired licensees to confirm that thsf r ;erating reactors would continue to be ~in confor ance iith 10 :.:R 50..;6 I
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if the fiUREG-0630 models were substituted for the present materials models in-their ECCS evaluations (References 8 and 9).
Until we have completed our generic review and implemented new acceptance criteria der cladding models, we have required that the ECCS analyses be accompanied by supplemental calculations to be performed with the materials models. of fiUREG-0630.
For these supplemental calculations only, we have accepted other compensatory model changes allowed for the confirmatory cperating reactor calculations centioned above.
By letters dated April 10,1981 and.May 5,1981 (Ref.10 & 11), the licensee provided a supple-(
mental ECCS calcul.. tion.
This calculation also accounted for a non-conservatism identified (Ref.12) by Westinghouse in their February,1978 ECCS evaluation model, which used a fast-heatup-rate' correlation for slow transients. Specifically, plant fleatup r.ates are at slow temperature-ramp rates; whereas, the evaluation model was,,in part, based on cladding tests that were conducted at fast temperature-ramp rates. The Zion submittal assessed the combined impact of this calculational error and.the final fiUREG-0630 models to be worth 855'F peak cladding temperature above that t
previously calculated. Subsequently Westinghouse calculated that a reduction ~
CF in total peaking factor, FQ3 0.03 would offset the tortion of the 855'F in-crease in peak cladding temperature that exceeded 2200*F.
Consequently an FQ redus. tion is required for Zion and the licensee has amended the Technical Specifications to reflect a new FQ of 2.17.
We, therefore, conclude that the applicant has satisfied our conce,rns related to the swelling and rupture issue.
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-5 d.0 CONCLUSIONS ine changes'in stored energy and the changes in SATAN modeld C t!echniques based on " UNI Technology" are acceptable for large i
break analyhis of the ECCS on Zion Station Units 1 and 2 as described in this SER.
They also meet the requirements of Accendix X to 10 CFR 50.
The accumulator volume sensitivity and the resulting worst case determination is also acceptable.
The licensee has suitably assessed the impact of the~ NUREG-Oti30 models i,n the sucolemental ECCS analysis.
s.
7.0 REFERENCES
1.
Letter from D.
L.
Peoples, Commonwealth Edison, to H.
R.
Denton, NRC, dated October 22, 1979.
2.
D.
A.
Powers and R.
O.
Meyer, " Cladding Swelling and Rupture Models for LOCA Analysis," NRC Report NUREG-0630, April 1980.
Available from the NRC Division of Technical Information and Docket Control.
3.
Letter from A.
Schwencer, NRC, to D.
Peoples, Commonwealth Edison, dated March'13, 1980.
1 l
4.
" Safety Evaluation Report en i' e s t i n g h o u s e Electric Ccecany ECCS Evaluation Model fer Plants Ecuirred with Uccer Head Injection," NUREG-0297, cublished by U.S.
Nuclear Reguia: cry Cc--
syicn in Aeril 197S.
i
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- v..
Y.
Young,. et al.,
" W e s t i n ; *. :.: l e E -' e r ;: e n c y Ocre Cccling Syster Evaluation Model Applicatien to Flan s E :u i ::: e c witr Upper bead Injection," WCAP-8479-P, Revision 2, November l
1977, Addendum 1, October 1979.
M.
i 6.
John F.
Stolz,'NPC, letter to T" M.
Anderson, Westinghouse,
" Safety Evaluation of WCAP-9220, Westinghouse ECCS Evaluation l
Model, February 1978 Ve r sion," dat ed S eh t embe r-5,197 8.
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7.
Memorandum from R.
P.
Denise, NRC, to R.
J.
M a t t s o ri, "Sunnary Minutes of Meeting on Cladding Rupture Temperature, CL' adding Strain, and Assembly Flow Blockage," November 20, 1979.
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Available in NRC PDR for inspection and copying for a fee.
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8.
Letter from D.
G.
Eisenhut, NRC, to ALL Operating Light Water
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Reactors, dated November 9, 1979.
Available fn NRC PDR for l
inspection and copying for a fee.
9.
M em o r an d utu from H.
R.
Denton, NRC, to Commission: Ps, " Potential Deficiencies in ECCS Evaluation Models," November 26, 1979.
Available in NRC PDF for inspection and copying for a fee.
10.
Letter from T. R. Tram, Comonwealth Edison, to S. A. Varga, NRC, dated April 10,1981.
11.
Letter from T. R. Tramt.Co=1onwealth Edison, to S. A. Varga, NRC, dated May 5,1981.
l 2.
'stter from T. M. Anderson,1.'estinghcase Electric Corporation, to D. G. Eiser.::
NRC, Number NS-T!'A-2163, dated fbvember 15, 1979.
P00RORl81[CL
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'I Environmental Consideration We have determined that the amendments do not authorize a change in effluent types or. total amounts nor an increase in power level and will not result in any significant env'ironmental impact. Having made this determiaation, we have fJrther concluded that the amendments involve an action which is insignificant from the standpoint of environmental impact and, pursuant to 10 CFR s51.5(d)(4), that an environmental impact statement or negative declaration and environ-mental impact appraisal need not be prepared in connection with the issuance of these amendments.
Conclusion We have concluded, based on the considerations discussed above, that:
(1) because the amendments do not involve a significant increase in the probability or consequences of accidents previously considered and do not involve a significant decrease in a safety margin, the amendments do not involve a significant hazards consideration, (2) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the propcsed manner, and (3) such activities will be conducted in compliance with the Commission's regulations and the issuance of these amendments will not be inimical to the common defense and security or to the health and safety of the public.
Date:
May 11,1981 9
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