ML20137U023

Proposed Tech Spec Pages 3/4 2-8,3/4 2-10 & B3/4 2-4, Deleting Rod Bow Penalty

ML20137U023
Person / Time
Site:	Farley
Issue date:	11/27/1985
From:	ALABAMA POWER CO.
To:
Shared Package
ML20137U016	List: ML20137U011 ML20137U023
References
TAC-60291, TAC-60292, NUDOCS 8512090184
Download: ML20137U023 (11)

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' Attachment 1-

. Proposed Cnanged~Pages Unit'1 Revision c..

-Page_3/4'2-8 Replace Page 3/4~2-10, Replace Page B3/4 2-4 Replace Unit'2 Revision Page 3/4 2-8 Replace

~Page 3/4 2-10 Replace Page B3/4 2-4 Replace

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POWER DISTRIBUTION LI'MITS'

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-3/4.'2.3-NUCLEAR-ENTHALPYHOTCHANNELFACTOR-FNLH LIMITING CONDITION =FOR OPERATION

N 3.2.3. F JL H shall be111mited by 'the following relationship:

FIH<1.55-[1+'O.3(1-P)]

THERMAL POWER where P = RATED THERMAL POWER 4

APPLICABILITY: MODE 11 ACTION:

~.With F"2LH exceeding its limit:

Ja.

R' educe THERMAL POWER to less than'50% of RATED THERMAL POWE5 within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> and reduce the Power Range Neutron Flux-High Trip Setpoints to <-

55% of RATED THERMAL POWER within the next 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />, b.

Demonstratethroughin-coremappingthatF$sHiswithinitslimit within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> after exceeding the limit or reduce THERMAL POWER to less than 5% of RATED THERMAL POWER within the next 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />, and c.

Identify and correct the cause of the out of limit condition prior to increasing THERMAL POWER above the reduced limit required by g or b, above; subsequent POWER OPERATION may proceed provided that FA H is

-demonstrated through in-core mapping to be within its limit at a nominal 50% of RATED THERMAL POWER prior to exceeding this THERMAL POWER, at a nominal 75% of RATED THERMAL POWER prior to exceeding this THERMAL POWER-and within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> after. attaining 95% or greater RATED THERMAL POWER.

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.FARLEY-UNIT l' 3/4 2-8 AMENDMENT NO.

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3/4 2-10 AMENDMENT NO.

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. POWER DISTRIBUTION LIMITS BASES F[

will be maintained within its limi s provided conditions a. through id. above"are maintained. The relaxation of F H as a function of THERMAL POWER

- allows changes in the radial' power shape for all permissible rod insertion limits.

When an F measurement l-te. ken, an allowance for both experimental error 0

and manufacturmg tolerance must be made. An allowance of 5% is appropriate for a full. core map;taken with the incore detector flux mapping system and a 3%

allowance is appropriate for. manufacturing tolerance.

When F H is measured, experimental error must be allowed for and 4% is theapproprfateallowanceforafullcoremaptakenwiththeincoredetection system. The specified limit for F1 g also contains an 8% allowance for uncertainties which mean that normal operation will result in Fg < 1.55/1.08.

The 8% allowance is based on the following considerations

a.

Abnormal perturbations in the radial power shape, such as from rod y

misalignment, effect F more directly than Fg, gg b.

Although rod movement has a direct influence upon limiting F to withinitslimit,suchcontrolisnotreadilyavailabletolbitF N AH and c.

Errors in prediction for control power shape detected during startup physicstestscanbecompensatedforigFg by restricting axial flux distribution. This compensation for Fgg is less readily available.

Fuel rod bowing. reduces the value of DNB ratio. Credit is available to 1 ' offset this reduction in the generic margin. The generic design margins,

_ totaling 9.1% DNBR, completely offset any rod bow penalties. This margin includes the following:

1) Design limit DNBR of 1.30 vs. 1.28

2) Axial Grid-Spacing Coefficient (Ks) of 0.046 vs. 0.059

3) Thermal Diffusion Coefficient of 0.038 vs. 0.059

4) DNBR Multiplier of 0.865 vs. 0.88 5)' Pitch reduction i

e FARLEY-UNIT 1 B 3/4.2-4 AMENDMENT NO.

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~ POWER DISTRIBUTION LIMITS' N

3/4.2.3 NUCLEAP~ENTHALPY HOT CHANNEL FACTOR - F2sH

. LIMITING CONDITION FOR OPERATION N-3.2.3 F46H shall be limited by the following relationship:

N-FAH < 1.55 [1 + 0.3 (1-P)]

. THERMAL POWER

where P =: RATED THERMAL POWER.

-APPLICABILITY: -MODE 1 ACTION:

N.

With' FAH exceeding. its limit:

a. : Reduce THERHAL POWER to less than 50% of RATED THERMAL POWER within 2

- hours and reduce the Power Range Neutron Flux-High Trip Setpoints to <-

55% of RATED THERMAL POWER within the next 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />, N

b.1 Demonstrate through in-core mapping that FikH is within its limit within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> after exceeding the limit or reduce THERMAL POWER to less than 5% of RATED THERMAL POWER within the next 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />, and c.

Identify and correct the cause of the out of limit condition prior to increasing THERMAL POWER above the reduced limit required by g or b, above; subsequent POWER OPERATION may proceed provided that FaH is demonstrated through in-core mapping to be within its limit at a nominal 50% of RATED THERMAL POWER prior to exceeding this THERMAL POWER, at a nominal 75% of RATED THERMAL POWER prior to exceeding this THERMAL POWER and within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> after attaining 95% or greater RATED THERMAL-POWER.

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FARLEY-UNIT 2 3/4 2-8 AMENDMENT N0.

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Fk :will be maintained within'its limitg provided conditions a. through

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d. above are maintained.- The relaxation of Fa H as a function of THERMAL POWER allows change 3 in the radial power shape for all permissible rod insertion -

limits.

When an F o - measurement is taken, an allowance for both experimental error and manufacturihg tolerance must.be made. An allowance of 5% is appropriate for a full core map taken with the incore detector flux mapping system and a 3%

. allowance'is appropriate for manufacturing tolerance.

. hen F '

is measured, experimental error must be allowed for and 4% is W

'theapproprht"eallowanceforaful core map taken with the incora detection

-system. The specified limit for also contains an 8% allow y ce for uncertainties which mean that norma operation will result in FfH ~< 1.55/1.08.

The 8% allowance is based:on the following considerations:

.a.

Abnormal perturbations n the radial power shape, such as from rod misalignment, effect more directly than F Q,

b. [Although rod movement has a direct influence upon limiting F to within its limit, such control is not readily available to liSit UAH e

and c.

Errors in prediction for control power shape detected during startup physics tests can be compensated for i F g by restricting axial flux distribution. This compensation for F H is less readily available.

Fuel rod bowing reduces the value of DNB ratio. Credit is available to offset this reduction in the generic margin. The generic-design margins, totaling 9.1% DNBR, completely offset any rod bow penalties. This margin includes the following:

1) Design limit DNBR of 1.30 vs. '1.28

2) Axial Grid Spacing Coefficient (Ks) of 0.046 vs. 0.059

3) Thermal Diffusion Coefficient of 0.038 vs. 0.059

4) DNBR Multiplier of 0.865 vs. 0.88

5) Pitch reduction FARLEY-UNIT 2 B 3/4 2-4 AMENDMENT N0.

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- s Significant Hazards Evaluation Pursuant to 10 CFR 50.92 i

for the Proposed Removal of the Rod Bow Penalty

.from the Technical Specifications Proposed Change Remove the Rod Bow Penalty (RBP) from the Units 1 and 2 Technical Specification 3.2.3 and revise the corresponding discussion in the bases.

Background

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-The phenomenon of fuel rod bowing in Westinghouse PWRs is considered in the departure from nucleate boiling ratio (DNBR) safety analysis of Farley Nuclear

-Elant Units 1 and 2.

In'the'early 1970s much larger fuel rod bowing than had.

been predicted was observed in Westinghouse low parasitic (LOPAR) fuel L

f.!

assemblies. Due to this larger rod bow,' the DNBR analyses were reevaluated.

Subsequently,' the DNBR effects due to rod bow were redefined and a rod bow penalty (RBP) was applied to the technical specification calculation of F N. Additionally, the RBP as a function of burnup was defined in the ATechnical Specifications by the addition of Figure 3.2-3._

In an effort.to gain insight into the extent and effect of fuel rod bow on DNBR Westf ; house Electric Corporation has obtained data from irradiated fuel assemblier-In 1975 sufficient rod bowing information was 'available to develop an empirical model to predict rod bow as a ' function of region average

'burnup. This-information and the effects of predic,ted rod bowing on power peaking and DNf2 analyses were presented in the original WCAP-8691, which was

~

submitted _for NRC review'in_ January 1976. Revision.1 of.WCAP-8691 (Reference 1) and References 2 and 3 document subsequent NRC inquiries and Westinghouse responses. The Westinghouse methods for predicting the effects

.of rod bow on'DNB as described in the above documents were approved by the NRC staff in Reference 4 WCAP-8691 Revision 1 and References 2 and 3 have successfully demonstrated that applicable generic credits for margin resulting from retained c.

I conservatism in the evaluation of DNBR and/or margin obtained from seasured

~ lant operating parameters, which are less limiting than those required by the p

plant safety analysis, can be used'to offset the effect of rod bow. The nazimua DNBR penalty which must be accounted for is < 3% at 33,000 MWD /MTU as identified in Reference 3.

The safety analyses for Farley Nuclear Plant Units 1 and 2 maintained sufficient margin to accommodate full and low flow DNBR penalties. This margin totals 9.1% DNBR and includes the following:

DNB Marain %

a.

Design limit DNBR of [1.30 vs. 1.28],

1.6 b.

Axial Grid Spacing Coefficient (K,) of

[0.046 vs 0.059),

2.9 4

D

)

p -- e DNB Marsin %

c., Thermal Diffusion Coefficient of

[0.038.vs 0.059],

1.2

d.L 'DNBR Multiplier of - [0.865 vs 0.88], and 1.7

e. 1 Pitch reduction.

1.7

~

Total:

9.1%

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This margin is' adequate to offset all rod. bow penalty for assembly average p

- burnups of up'to 33,000 MWD /MTU. The maximum rod bow penalties ~ accounted for

'in the design safety analysis are based on an assembly average burnup of 33,000 MWD /MTU. At burnups greater than 33,000 MWD /MTU, credit is taken for 4

the-effectofFNburndown,'duetothedecreaseinfissionableisotopes A

and the. buildup of' fission product inventory, and no additional rod bow

- penalty is required.

References (1) Skaritka, J., - (Ed), " Fuel Rod Bow Evaluation," WCAP-8691, Revision l1

~ July 1979, (Proprietary).

(2);" Partial-Response to Request. Number 1 for Additional Information on WCAP-8691, Revision 1" letter, E. P. Rahe, Jr., (Westinghouse) to J. R. Miller (NRC), NS-EPR-2515, dated October 9,1981, '(Proprietary).

(3) " Remaining Response to Request Number 1 for Additional Information on

[

--WCAP-8691, Revision 1" letter,' E. P. Rahe, 'Jr., ~ (Westinghouse) to J..R. Miller (NRC), NS-EPR-2572, dated March 16, 1982, (Proprietary).

l-

- (4) NRC letter from C. Thomas, NRC, to E. P. Rahe, Westinghouse dated December 29, 1982.

1

. Analysis Alabama Power Company has reviewed the requirements of 10 CFR 50.92 as they -

relate to the proposed deletion of the rod bow penalty from the technical specificationcalculation~ofFlandconsiderstheproposedchangenotto A

involve a significant. hazards consideration.

In support of this conclusion the following analysis is provided:

t

- 1) The proposed change will not significantly increase the probability or consequences of an accident previously evaluated because an adequate aargin of safety to the minimus DNBR of 1.30 will be maintained for those J

transients which must account for the phenomenon of fuel rod b.owing in the DNBR safety analysis (i.e., Condition I and Condition II events).

2) The proposed change will not create the possibility of a new or different

^ kind of accident from any' accident previously evaluated because the plant configuration or mode of operation is_not altered by the removal of the rod bow penalty. Adequate margin exists in the plant safety analysis to allow operation without the requirement for any DNBR related rod bow penaity.

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3) The. proposed change will not involve a significant reduction in margin of safety-because the safety analyses for Farley Nuclear Plant Units 1 and 2 maintain aufficient margin to accommodate the removal of all rod bow penalties related to DNBR and the margin within the existing DNBR limits remains unaffected.

Conclusion

.y Based upon the analysis provided herewith, Alabama Power Company has determined that the proposed technical specification change will not significantly increase the probability or consequences of an accident previo0 sly evaluated, create the possibility of a new or different kind of accident from any accident previously evaluated, or involve a significant reduction in a margin of safety. Therefore, Alabama Power Company has detemined that the proposed change meets the requirements' of 10 CFR 50.92(c) and does not involve a significant hazards consideration.

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