ML20236L528

Application for Amends to Licenses DPR-42 & DPR-60,changing High Flux,Power Range Monitor,Low Setpoint

ML20236L528
Person / Time
Site:	Prairie Island
Issue date:	11/03/1987
From:	Musolf D NORTHERN STATES POWER CO.
To:
Shared Package
ML20236L521	List: ML20236L519 ML20236L528 ML20236L544 ML20236L589
References
NUDOCS 8711100392
Download: ML20236L528 (3)

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-UNITED STATES ' NUCLEAR . REGULATORY COMMISSION q

i NORTHERN STATES POWER COMPANY 'e PRAIRIE ISLAND NUCLEAR GENERATING PLANT .DdCKET Nd. 50-282- '

50 306.-

REQUEST'FORLAMENDMENT TO <

OPERATING LICENSE DPR-42 & DPR-60; -

LICENSE AMENDMENT REQUEST DATED November;3, 1987 1 Northern States Power Company, a Minnesota! corporation, requestsj authorizationIfor changes.to Appendix lA of"the: Prairie Island-Operating License as shown on the.attachmentsLlabeled Exhibits A, B,:, .i C, and D. Exnibit A describes the proposed changes,' describes the recsons for the: changes, and contains<a:significant hazards eval-- 1

'uation. Exhibits B and C.are copies of the.Pra!rie IslandLTechnical i Specifications it.corporating the proposed changes. l Exhibit'D is' ,

1 a report supporting the requested changes.

l This letter contains no restricted or other defense information. -

NORTHERN STATES POWER COMPANY By J Q.

David Musolf \

Manager-Nuclear SupporMServices

-l On this 3 day of ele /;;/7 before me a' notary public in and for said Coun6y, personalfy' appeared David Musolf, Manag- j er-Nuclear Support Services, and being first duly sworn acknowl-edged that he is authorized to execute this~ document on behalf of 1 Northern States Power Company, that he.knows the contents there- .

of, and that to the best of his knowledge, information-, and be '  !

lief the statements made in it are trua. and that.is is not inter-posed-for delay,

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- ANOKA COUNTY- U Ny Comnuen Enru Sept. 5. IMI <

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G711100392 87.1103  ;

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- 1 EXHIBIT A Prairie Island: Nuclear Generating Plant License Amendment Reauest Dated November'3. 1987 Evaluation of Proposed: Changes to the;

. Technical Specifications Appendix A of Operating License DPR-42 and'DPR-60 Pursuant to 10 CFR Part'50, Sections 50.59 and 50.90, the holders of Operating Licenses'DPR-42.and DPR 60 hereby propose the following changes 1 to Appendix A, Technical Specifications: j High Flux. Poupr Rance. Low Set Point j

l Erososed ages (TS 2.3.A.1.b) f Chal6" dh flux, power range (low set point) to read, "s 40% of rated power.'.

Ega pn For Change l

The current Technical Specification of 25% for.this high flux, power l range low set point is unnecessarily restrictive. '

Calibration of the Nuclear Instrumentation System (NIS) power range l channels is performed using calorimetric data taken during the startup l physics testing program. During the power escalation program following' 1 the Unit 1 Cycle 11-12 refueling outage, at an indicated power of 34.6%,

calorimetric data showed that actual power was 45.7%. This was caused by a greater-than-predicted change in radial neutron leakage resulting from a change in core loading patr.crn and differences in core conditions at the time of calibration from Cycle 11 to Cycle 12. The effect of these differences was that the high flux, power range low set point would have tripped the reactor at an actual power of about 33%, (8% above the current technical specification set point of 25%) as reported in Licensee Event Report 87-014. The methods of calculating the neutron leakage have been reviewed. It was determined that a substantial effort would be necessary to refine the prediction. It was also concluded, that due to 1 the nature of these calculations, significant error is expected to remain following core loading pattern changes even if improvements were i incorporated. Since changes in these calculations are not practical, we j

have performed analyses to justify a set point change. I Analyses have been performel by the Northern States Power Nuclear l

Analysis Department assuming a high flux, power range low set point at an actual power of 40% (See Exhibit D). These analyses demonstrate  ;

acceptable results utilizing 406 of' rated power as the high flux, power 1 range low set point.

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, EXHIBfT A

3. The' proposed amendment will not involve a'significant reduction in the' margin of safety.

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The transients contained in the FSAR. t ich are affected by a change  !

- in the set. point of the high flux, power range low set point are an:

Uncontrolled RCC Assembly Withdrawal From a Suberitical Condition ~and a Rupture of Control . Rod Drive Mechanism Housing (RCCA Ejection) 2 from 1 hot zero power (HZP)' conditions. These transients 1have been  !

reanalyzed utilizing methods which have been reviewed and approved by' the NRC. For the Uncontrolled RCC Assembly _ Withdrawal.From a i Suberitical Condition the analyses demonstrate that the. primary and I secondary pressures do not exceed the' system design pressures'and j that the fuel cladding integrity is maintained since the peak clad' j temperature for this transient is.less than'even the nominal full' l power value. For the RCCA. Ejection from HZP conditions the - analyses demonstrate that the average hot spot fuel enthalpy, maximum' reactor j coolant system pressure and maximum clad temperature'are all-below '

the established acceptance criteria. Based on the results of the~

transient analyses performed, it has been concluded that the proposed-amendment does not significantly reduce the margin of safety.

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The commission has provided guidance (March 6,'1986 Federal Register) concerning the application of the' standards'in-10 CFR 50'92 for.

determining whether a significant hazards consideration exists by.  ;

providing certain examples of amendments that will likely be found'to involve no significant hazards considerations. ~he changes to the {

1 Prairie Island Technical Specifications proposed in this amendment I request are equivalent'to.NRC example (vi),.because they' involve changes which either may result in some change in the probability or consequences of a previously analyzed accident or may change-in some way a safety i margin, but where the results of the change are clearly within all transient analysis acceptance criteria. Based on this guidance and the ,

reason discussed above, we have concluded that the proposed changes do j not involve a significant hazards consideration.

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