NLS9000042, Application for Amend to License DPR-46,relaxing Safety Valve & Safety Relief Valve Setpoint Tolerance

Application for Amend to License DPR-46,relaxing Safety Valve & Safety Relief Valve Setpoint Tolerance

ML20006B463
Person / Time
Site:	Cooper
Issue date:	01/26/1990
From:	Kuncl L NEBRASKA PUBLIC POWER DISTRICT
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML19310C663	List: ML20006B463 ML20006B466 NLS9000042, Application for Amend to License DPR-46,relaxing Safety Valve & Safety Relief Valve Setpoint Tolerance
References
NLS9000042, NUDOCS 9002020247
Download: ML20006B463 (5)

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GENERAL OFFICE Nebraska Public Power District

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au NLS9000042 January 26, 1990

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i U.S. Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 j

l Centlemen:

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Subj ect:

Proposed Change No.- 66 to Technical Specifications Safety Valve'and Safety Relief Valve Setpoint Tolerance Cooper Nuclear Station-NRC Docket No. 50-298, DPR-46 In accordance with the applicable provisions specified in 10 CFR 50, Nebraska Public Power District requests that the Cooper Nuclear Station

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Technical Specifications be revised to-relax the setpoint. tolerance for.

I both the safety valves and safety relief valves from-11%- to 13%; This j

proposed revision is in agreement with: relaxed criteria adopted by-thefASME in Subsection IWV-3500 of the ASME~ Code, Section'XI, 1986 Edition,

,j The attachment to this letter contains L a fdescription of the proposed changes, the basis for our determination = that the-proposed ' changes. o not d

involve significant hazards considerations per 10.CFR 50.92, and the j

revised Technical Specification pages. As part of thi'sLattachment, the District is submitting "SRV Setpoint Tolerance Analysis For-Cooper Nuclear y

Station", NEDC-31628P, prepared for the District'by theLGeneral Electric

Company, General Electric considers the information. contained in this document to be proprietary and requests that it be. withheld from public-disclosure. An affidavit to this.effect is also attached as required by:

10 CIT 2.790.

This proposed change has been reviewed by the necessary Safety Review Committees and-incorporates all amendments-to.the CNS Facility Operating License through Amendment 130 issued May 24, 1989.

In addition to the signed original, 37 copies are also submitted for your-By copy. of this letter and attachments the-appropri' ate State ' of I

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Nebraska official is being' notified in accordance with 10 CFR 50.91(b)(1).

Copies to the NRC Region IV Office and the' CNS Resident ! Inspector are also being sent in accordance with 10 CFR 50.4(b)(2).

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- January 26, 1990-Page 2 i

i Should you have any questions or require additional information, please contact me.

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ely,

- l L.-G;.-K nel 5

Nuclear' Power Group Manager

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~t Attachments-(2) cc:

H. R. Borchert'.

i Department of Health

. State of Nebraska.

i NRC Regional Office Region IV Arlington, TX

.i NRC Resident Inspector Office Cooper Nuclear Station 1

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NLS9000042 January 26, 1990 Page 3 l

STATE OF NEBRASKA)

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.i PLATTE COUNTY

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L. G. Kunci,' being first duly sworn, deposes and says that he is an_

authorized representative of.the Nebraska Public Power District,-a public?

. corporation.and political subdivision of the State of Nebraska; that he is:

duly. authorized to submit this request on behalf of Nebraska Public Power.

District; and that the statements contained herein are true to the best'of his' knowledge and belief.

4 L*, G. Kunc1 i

i Subscribed n my presence and sworn to-before.me thist c2k d day of.

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PROPOSED CHANGE NO. 66 COOPER NUCLEAR STATION TECHNICAL SPECIFICATIONS SAFETY VALVE AND SAFET( RELIEF VALVE SETPOINT TOLERANCE -

l DESCRIPTION OF CHANGE REQUEST The Cooper Nuclear Station (CNS) Technical Specifications currently require that the setpoints for both the safety valves (SVs) and safety relief valves (SRVs) remain within a t1% tolerance band. During each outage, approximately half of the valves are tested to demonstrate that they will open within 1% of their nominal'setpoint.

In the past, some of these valves have experienced upward setpoint drift in excess of' the 1% tolerance. Each time this has occurred, a Licensee Event Report has been submitted to demonstrate that there is no safety concern associated with failure to-i meet this Technical Specification requirement.

The narrow 1% tolerance band on the SV and SRV setpoints specified in thel t

Technical Specifications stems from the original acceptance criterion defined by the ASME for in-service performance testing. The ASME has since relaxed the' criterion '

for demonstrating valve operational readiness from 1% to 3%. Although the 1%;

tolerance has been utilized in past plant safety evaluations,-it does not necessarily represent the limiting opening pressure required to ensure plant safety.

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A new safety evaluation, "SRV Setpoint Tolerance Analysis For Cooper Nuclear j

Station", NEDC-31628P, has been performed by the General Electric Company and is attached. This evaluation provides a determination of an upper limit for the SRV i

opening pressure such that safe plant operation is ensured without affecting the health L and safety of the public. An upper limit has been selected to ensure that the calculated peak vessel pressure does not exceed the ASME upset code limit for the limiting overpressure event.

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It should be noted that it is still intended to reset all SRVs and SVs to within t1%

i of their nominal setpoint prior to being returned to service.. This.will ' ensure that.

valve performance will remain as before, and that the probability of setpoint drift will not be increased.

I The attached analysis concludes th5t an upper limit value of 1210 psig on the SRV opening pressure and 1277 psig for the SVs is acceptable, and has no significant safety 1

impact on vessel overpressure margin, thermal limits, ECCS/LOCA performance,.

HPCI/RCIC performance, containment response, containment integrity, or steam line j

integrity. Consequently, the Technical Specification surveillance requirement on both -

j the SRVs and SVs can be increased to 3% without impacting plant safety or creating.

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any significant operational concerns. Future reload licensing evaluations will verify l

the cycle-specific applicability of this analysis. Specifically, the limiting overpressure event will be analyzed with the SRV opening pressure at the upper limit of 1210 psig '

and the SVs at 1277 psig to verify that vessel overpressure limits are not exceeded.

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'j The District also requests that Specifications 4.6.D.3 and 4.6.D.4.be deleted for clarification. These specificat pps spply to three stage valves which are no longer used i

at CNS. The three stage valves were replaced with two stage valves in 1980, as reported in the CNS Annual Report dated March 1,1981; and there are no plans to return to the use of three stage valves.

1 DETERMINATION OF NO SIGNIFICANT HAZARDS 1.

The proposed change will not involve a sienificant increase in the probability or conseauences of an accident oreviousiv evaluated, because the transient and-accident consequences are within tlie required acceptance criteria. The valve nominal i

setpoints are not being changed. The valve setpoints will be returned to within 1%

of their nominal setting before being returned to service so valve performance is not -

l affected.

The recommended surveillance requirements and testing ensure that i

expected valve performance will remain as before.--

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The oronosed channe will not create the oossibility of a new or different kind of accident fro'm any previousiv evaluated. because the proposed change does not' l

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introduce a hardware change, and the performance of the SVs and SRVs is not' affected. The valve setpoints will be returned to within 1% of their nominal setting before being returned to service so valve performance is not affected. The valves will continue to fulfill their design objective, which is to prevent overpressurization of the nuclear system.

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The proposed change will not involve a significant reduction in a margin of safety, because the transient and accident consequences will remain-within the required acceptance criteria. The valve nominal setpoints are not being changed and -

valve performance is not affected. The surveillance requirements and testing ensure-that expected valve performance will remain as before.

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