ML20126E844

Safety Evaluation Supporting Amend 18 to License NPF-2

ML20126E844
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Site:	Farley
Issue date:	02/13/1981
From:	Office of Nuclear Reactor Regulation
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ML20126E841	List: ML20126E838 ML20126E844 ML20126E848
References
NUDOCS 8103040077
Download: ML20126E844 (3)

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UNITED STATES

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J WASHINGTON. D. C. 20555

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i SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION' i

SUPPORTING AMENDMENT NO.18 TO FACILITY OPERATING LICENSE NO. NPF-2 ALABAMA POWER COMPANY JOSEPH M. FARLEY NUCLEAR PLANT, UNIT NO.1

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f DOCKET NO. 50-348 9

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. Introduction 9

By letter dated March 28,1980-(supplemented by. letter dated January 5,1981) in response to our letter dated December 12,- 1980, Alabama Power Company. (APCO) proposed Technical. Specification changes. These changes related to a. proposed new Rod Eow Penalty (RPB) curve and the associated Bases. Additionally, by letter dated. January 9, 1981 (suoplemented by let er dated January 23,1981),.

f DC0 :rc:: sed new heatup and cooldown curves and bases.

These new cu rves re-i s its: # :- evaluation of a reactor vessel raterial s:ecimen (Capsule. Y) a f ter '.~." effective full power years of operation.

We havs t:e -in: changes I: the A:00 r:o:sals. These chances have been

<. - -hi APCO sta f # wno concur wi-h our changes. Our discussion discusse:

and eva' 5-':. are includec cerein.

Discuss':

a : Evaluation 1.

F.: : i :.- :ereicy Curve

( Fi; -e.:.2 - 3 a n: Eases)

An F','.,, penalty due to fuel rod bowing was approved for Farley Unit No.1 9'

TechWical Specifications in License Amendment No. 8.

The penalty - commences l

at. a region-averaged burnup of 400 mwd /MtU and parabolically increases-with addi-ional exposure. By letters of March 28, 1980 and January 5,1981, APC0 l

ore:!se: cnanges to Technical Soecifications Figure 3.2-3 and associated bases.

AKO proposed the elimination of the penalty because:

'a) -he proposed use of a recently soproved thermal-hydraulic model, and

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ne application of a plant-soecific margin available to offset DN3n reductions due to fuel rod bowing.

y Subsecuent to.NRC approval. of the present F' penalty, Westinghouse submitted

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1/ test results on the effects of a bowed.r5d on critical heat flux. These.

esuits showed a significant reduction in the presupposed DNBR penalty associated

'81030400 9 1/ Letter from C. 'Eiche1dinger,. Westinghouse, to D. F. Ross, NRC, NS.

j 2_4 _197 7. ____.._. _,

.CE.1580.9..Oc. to ber g

. with a small gap (specifically, the gap was equivalent to 85% closure).

Consequently, the NRC approved 2] the use of a less conservative model for the reduction in DNBR versus gap closure for Westinghouse applications.

By letter of March 28,1980, APC0 requested the use of this revised DNBR versus closure model for the Farley Unit No.1 rod bowing penalty calcu-lations. Since we had approved this model generically, the APC0 proposal to use this revised DNBR versus closure model is acceptable.

Using the revised model and available generic thermal margins totaling 9.1".

DNBR, APC0 first requested a reduction in the DNBR penalty. This proposal was ' subsequently revised by letter of January 5,1981 to ar. count for a plant-specific thermal margin of 3% DNBR. The combination of the generic margin plus plant-specific maggins are now sufficiently large to completely elimin-ate the reduction in F due to fuel rod bowing.

AH We previously approved 3/ the 9.1% DNBR margin for fuel designs such as is used in Farley Unit No. I and find its use in this application to be acceptable.

The 3% DNBR margin arises from the difference between the 1.3 DNBR safety limit and the minir.um DNBR calculation for the loss-of-flow accident. This.

3% margin was also previously approved for the Farley Unit No. 2 Technical Specifications.

Concl usion Since the thermal-hydraulic analysis of both Farley Units are identical, the application of the margin to Unit No.1 is acceptable as well. We, therefore, agree with APC0 in concluding that there is no longer a need to perform rod bowing penalty calculations for Farley Unit No.1 This conclusion, however, is cremised upon the ability of APCD to maintain at least 2.1% of the present plant-specific 3% DNBR margin.

In future cycles wnere the required 2.l*; DNBR margin g'ight not be evailable APC0 should determine the magnitude of any res-idual F.g penalty by use of the new Technical Scecifications Figure 3.2-3.

Figure 3.2-3 is not presently needed for Unit No.1 peration although it is retained for the stated reason.

2.

Heatuo and Cooldown Curves (Specification 3/4.4.9 and Bases 3/4.4.9)

Discussion and Evaluation We have reviewed the Updated Reactor Vessel Heatup and Cooldown Curves for the Joseph M. Farley Nuclear Plant, Unit No.1, submitted in APC0 letter dated January 9,1981.

-2/ Letter from J. F. Stolz, NRC, to T. M. Anderson, Westinghouse,

Subject:

Staff Review of WCAP-8691, dated April 5,1979.

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-3/ Memorandum from D. F. Ross and D. G. Eisenhut, NRC to D. B. Vassallo and K. R. Goller, " Interim Safety Evaluation Report on the Effects of Fuel Rod Bowing on Thermal Margin Calculations for Light Water Reactors," dated Cecember 8, 1976, 1

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As : art of our review, we have calculated the shift in the nil-ductibility transition temp'erature of the controlling iiiaterial in the beltline region of the reactor vessel (the intermediate to lower shell seam weld) to be 192*F after 7.7 EFPY operation. This is compared to an indicated shift of 185'F in the proposed updated curves for the Technical Specifications. i At the 1/4 t. location, this difference in shift' temperature corresponds to the fluence received by the vessel in 0.6 EFPY operation.

-Therefore, the Updated Reactor Vessel Heatup and Cooldown Curves should reflect the calculated decrease in fluence. Thus, we consider that the lic'itations should be applicable for 7 EFPY instead of 7.7 EFPY proposed.

Specification 4.4.9 and bases have been modified accordingly.

Conclusion

'n'ith ~tne changes which we have mad' e, we conclude -hat the Pressure-Temper-ature curves are acceptable and will be in conforman:e with Appendix G re;uirements.

Irv'-:mmental Consideration We

.a.e determined that the amendment dees not authorize a change in ef C uen-ytes or total amoun s nor an increase in power level and

*esult in any signifi:an: environmental impact.

Having made

e s :e:ermina-ion, we have further :encluded that the amencment

' v:'ves an action which is insignifi:an: from the standpeint of e v' :mmen al imcact and, oursuan :: 1 CFR s51.E(d)(4), that an ev d :mmental imcac statemen: er negative declara-f on and environ-e :g' it:a:: aporaisal need re be pre:ared in conne:: ion with the

.:s.an:e Of this amencment.

:';sien e

.a.e ::n:1udet, tased on re : nsi:e ations cis:Ussed above, thati

', :e:ause :ne amen:merr. d ces not involve a signift:an-increase i

i ne procability or consecuences of accidents previously considered and coes not involve a significant decrease in a safety margin, the amen: cent does not involve a significan: hazards consideration, (2) l nere is reasonable assurance that the health and safety of the public w i '., :: be endangered by operation in -he proposed manner, and (3) e I

l s;:r, i::ivities will be condu:ted in cameliance with the Commission's regu:t-ions and the issuance of this amendment will not be inimical

ne :ommon defense and security or to the heal-h and safety of

ne :ublic.

Cate:

February 13, 1981 l

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