NLS2011088, Response to Nuclear Regulatory Commission Request for Additional Information for Reducing the Number of Technical Specification 3.4.3 Required Safety Relief Valves

Response to Nuclear Regulatory Commission Request for Additional Information for Reducing the Number of Technical Specification 3.4.3 Required Safety Relief Valves

ML11297A033
Person / Time
Site:	Cooper
Issue date:	10/18/2011
From:	Dori Willis Nebraska Public Power District (NPPD)
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NLS2011088, TAC ME5287
Download: ML11297A033 (6)

Text

N Nebraska Public Power District Always there when you need us 50.90 NLS2011088 October 18, 2011 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555-0001

Subject:

Response to Nuclear Regulatory Commission Request for Additional Information for Reducing the Number of Technical Specification 3.4.3 Required Safety Relief Valves (TAC No. ME5287)

Cooper Nuclear Station, Docket No. 50-298, DPR-46

References:

1. Letter from Lynnea E. Wilkins, U. S. Nuclear Regulatory Commission, to Brian J. O'Grady, Nebraska Public Power District, dated June 3, 2011, "Cooper Nuclear Station - Request for Additional Information License Amendment Request for Reducing the Number of Technical Specification 3.4.3 Required Safety Relief Valves (TAC NO. ME5287)"

2. Letter from Brian J. O'Grady, Nebraska Public Power District, to the U.S.

Nuclear Regulatory Commission, dated January 5, 2011, "License Amendment Request for Reducing the Number of Technical Specification 3.4.3 Required Safety Relief Valves"

3. Letter from Brian J. O'Grady, Nebraska Public Power District, to the U.S.

Nuclear Regulatory Commission, dated October 6, 2011, "Supplement to License Amendment Request for Reducing the Number of Technical Specification 3.4.3 Required Safety Relief Valves"

Dear Sir or Madam:

The purpose of this letter is for Nebraska Public Power District (NPPD) to submit a response to a request for additional information (RAI) from the Nuclear Regulatory Commission (NRC)

(Reference 1). The RAI requested information in support of NRC's review of a license amendment request (LAR) for the Cooper Nuclear Station (CNS) Technical Specifications (TS) to revise TS 3.4.3, "Safety/Relief Valves (SRVs) and Safety Valves (SVs)" to reduce the number of SRVs required to be OPERABLE for over-pressure protection (Reference 2).

Responses to the specific RAI questions were discussed in a public telephone conference on July 12, 2011. Afterwards, the NRC requested these responses be submitted to the public docket, and they are provided here in the Attachment with revisions as discussed. Subsequent to the public COOPER NUCLEAR STATION V 0oI P.O. Box 98 / Brownville, NE 68321-0098 Telephone: (402) 825-3811 / Fax: (402) 825-5211 ww-w.nppd .com

NLS2011088 Page 2 of 2 teleconference, NPPD decided to supplement the LAR and request seven of eight rather than five of eight SRVs (Reference 3). No regulatory commitments are made in this submittal.

The information submitted by this response to the RAI does not change the conclusions nor the basis of the no significant hazards consideration evaluation provided with Reference 3.

If you have any questions concerning this matter, please contact David Van Der Kamp, Licensing Manager, at (402) 825-2904.

I declare under penalty of perjury that the foregoing is true and correct.

Executed on (da/a ID I(dafe)

Sincerely, Demetrius L. Willis General Manager of Plant Operations

/em Attachment cc: Regional Administrator w/ attachment USNRC - Region IV Cooper Project Manager w/ attachment USNRC - NRR Project Directorate IV- 1 Senior Resident Inspector w/ attachment USNRC - CNS Nebraska Health and Human Services w/ attachment Department of Regulation and Licensure NPG Distribution w/o attachment CNS Records w/ attachment

NLS2011088 Attachment Page 1 of 3 Attachment Response to Nuclear Regulatory Commission Request for Additional Information for Reducing the Number of Technical Specification 3.4.3 Required Safety Relief Valves (TAC No. ME5287)

Cooper Nuclear Station, Docket No. 50-298, DPR-46 Ouestion #1 Please discuss if all cases were analyzed (i.e., all transients addressed).

Response

As discussed in the public teleconference on July 12, 2011, the Safety Relief Valve (SRV) analysis was performed for the limiting cases of Transients and Special Events, i.e. most bounding. Licensing-Basis for Over-Pressure Protection (OPP) identifies the limiting transient to be Main Steam Isolation Valve (MSIV) fast closure followed by a high neutron flux scram. The limiting special event for OPP is the Anticipated Transient Without Scram (ATWS) with MSIV closure or pressure regulator fails open.

Ouestion #2 Please discuss the number of SR Vs that are neededfor operation as described in the design basis calculations.

Response

Five SRVs are needed for operation. The GE Hitachi Reports provided with Reference 1 are now the Cooper Nuclear Station (CNS) design analysis for the required number of SRVs.

Ouestion #3 Please discuss if these valves have caused a plant shutdown in the past.

Response

No. SRV failures have not caused a plant shutdown.

Ouestion #4 Please discuss the timing and increments related to SR V actuationfor the full range of transients.Please also discuss which five will be the "required"valves or, if the request is for anyfive, justify the basisfor the TS having only four SR Vs availablewhen in the Limiting Conditionfor Operation.

NLS2011088 Attachment Page 2 of 3

Response

Safety Valves (SVs) and SRVs actuate over the full spectrum of transients as follows. SVs spring tension is set at 1240 + 37.2 psig and provides blowdown of approximately 38 to 50 psig, and they relieve > 644,543 lbm/hr each.

Spring lift setpoints for SRVs 71A, 71B and 71G are set at 1100 + 33.0 psig and have capacity > 877,900 lbm/hr each. SRVs 71C, 71E and 71H are set at 1090 +/- 32.7 psig and have capacity > 870,000 lbm/hr each. SRVs 71D and 71F are set at 1080 +/- 32.4 psig and have capacity > 862,100 lbm/hr each.

The request was not for specifically identified SRVs, but for any five OPERABLE. After the July 12, 2011 public teleconference, Nebraska Public Power District (NPPD) decided to supplement the submittal and request seven of eight SRVs required in Technical Specifications (TS) Limiting Condition for Operation (LCO) 3.4.3 to be operable instead of five of eight. This will reserve two SRVs above the five required for OPP and ATWS when operating in a condition of one SRV inoperable as permitted by the LCO action statement.

Ouestion #5 Please discuss if humanfactors will affect the mitigation of an accident and, ifso, if a human factors analysis has been performed.

Response

Human Factors are not affected, because TS LCO 3.4.3 only affects the SRV pilot actuated spring lift function for OPP and ATWS. Manual actions are not required to mitigate OPP or ATWS consequences. No human factors analysis was required.

Ouestion #6 Please discuss if the maintenance rule was taken into consideration. What maintenance issues, if any, contributedto the needfor this request?

Response

Maintenance Rule Functional Failure (MRFF) Evaluations include two SRV functions:

MS-Fl 1, Maintain Reactor Coolant Pressure Boundary, and ADS-PF02, Prevent.

Overpressurization of the Nuclear System (Mechanical Components).

For SRV MRFFs, CNS noted the following. An MRFF does not exist if the SRV can perform its Safety Related Function; the design functions of SRVs are not being changed.

MRFF evaluations are performed for each failure, regardless of how many SRVs are required by TS. Since MR became effective, all SRV as-found bench test failures have

NLS2011088 Attachment Page 3 of 3 been evaluated for MRFF, and the only MRFF CNS has had was in 2003 when SRV 71 G on Main Steam Line 'D' lifted in excess of its Analytical Limit.

No maintenance issues contributed to the need for this request.

Ouestion #7 Please discuss how the reduction in requiredSR Vs affects the heat load in the suppressionpool.

Response

Suppression Pool heat loads for SRV lifts are bounded by the CNS Loss of Coolant Accident analysis values.

Ouestion #8 Please discuss any structuralissues that would be impacted.

Response

The analysis shows that Suppression Pool and Drywell structural components remain capable of coping with SRV lifts in response to the bounding events and transients.

Ouestion #9 For all the above, please discuss the basisfor concluding the change would not increase the probability/consequencesof an accident and not reduce safety margins as described in the Updated Safety Analysis Report.

Response

After the July 12, 2011 public teleconference, NPPD decided to supplement the submittal and request seven of eight SRVs required in TS LCO 3.4.3 to be OPERABLE instead of five of eight. The No Significant Hazards Consideration evaluation was revised and provided in Reference 3. It provides the new basis for concluding the change would not increase the probability/consequences of an accident and not reduce safety margins.

4 ATTACHMENT 3 LIST OF REGULATORY COMMITMENTS© ATTACHMENT 3 LIST OF REGULATORY COMMITMENTS04 Correspondence Number: NLS2011088 The following table identifies those actions committed to by Nebraska Public Power District (NPPD) in this document. Any other actions discussed in the submittal represent intended or planned actions by NPPD. They are described for information only and are not regulatory commitments. Please notify the Licensing Manager at Cooper Nuclear Station of any questions regarding this document or any associated regulatory commitments.

COMMITMENT COMMITTED DATE COMMITMENT NUMBER OR OUTAGE None 4 4.

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