L-MT-12-019, CFR 50.55a Requests Associated with the Fifth Ten-Year Inservice Testing Interval

CFR 50.55a Requests Associated with the Fifth Ten-Year Inservice Testing Interval

ML12059A402
Person / Time
Site:	Monticello
Issue date:	02/28/2012
From:	O'Connor T Xcel Energy, Northern States Power Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
L-MT-12-019
Download: ML12059A402 (8)

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' Xcel EnergyB Monticello Nuclear Generating Plant 2807 W County Rd 75 Monticello, MN 55362 February 28,2012 L-MT-12-019 10 CFR 50.55a(f)

U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555-0001 Monticello Nuclear Generating Plant Docket 50-263 Renewed License No. DPR-22

Subject:

10 CFR 50.55a Requests Associated with the Fifth Ten-Year lnsewice Testing Interval Pursuant to 10 CFR 50.55a(a)(3)(i), the Northern States Power Company, a Minnesota corporation (NSPM), doing business as Xcel Energy, the licensee for the Monticello Nuclear Generating Plant (MNGP), hereby requests NRC authorization or approval of the enclosed 10CFR50.55a requests associated with the Fifth lnservice Testing (IST)

Interval for Monticello Nuclear Generating Plant (MNGP).

Relief Request No. VR 04 (enclosed) requests authorization to implement ASME Code Case OMN-17, Revision 0, "Alternative Rules for Testing ASME Class 1 Pressure RelieflSafety Valves", for the testing frequency on the Class 1 Main Steam SafetyIRelief Valves on the basis that the proposed alternative provides an acceptable level of quality and safety. This 10 CFR 50.55a request has been authorized for other NRC licensees.

NSPM requests the NRC authorize this 10 CFR 50.55a requests by March I , 2013, to support implementation of the IST fifth ten-year interval. This 10 CFR 50.55a request is proposed for the duration of the IST fifth ten-year interval.

Should you have questions regarding this letter, please contact Mr. Randy Rippy at (612) 330-6911.

Document Control Desk Page 2 Summaw of Commitments

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w commitments and no revisions to existing commitments.

Northern States Power Company-Minnesota Enclosure cc: Administrator, Region Ill, USNRC Project Manager, Monticello Nuclear Generating Plant, USNRC Resident Inspector, Monticello Nuclear Generating Plant, USNRC

ENCLOSURE MONTICELLO NUCLEAR GENERATING PLANT PROPOSED ALTERNATIVE IN ACCORDANCE WITH 10 CFR 50.55a(a)(3)(i)

RELIEF REQUEST VR04 5 pages follow

Monticello Nuclear Generating Plant Revision 0 VALVE RELIEF REOUEST NUMBER - VR 04 Use of Code Case OMN-17, Revision 0, on the Class 1 Main Steam Safety Relief Valves Proposed Alternative In Accordance with 10CFR50.55a(a)(3)(i)

On the basis that the proposed alternative provides an acceptable level of quality and safety.

1. ASME Code Component(s) Affected RV-2-71A, Main Steam SafetyIRelief Valve (ADS) (Class 1)

RV-2-71B, Main Steam SafetyIRelief Valve (Class I )

RV-2-71C, Main Steam SafetyIRelief Valve (ADS) (Class 1)

RV-2-71Dl Main Steam SafetyIRelief Valve (ADS) (Class 1)

RV-2-71El Main Steam SafetyIRelief Valve (Low-Low Set) (Class 1)

RV-2-71F, Main Steam SafetyIRelief Valve (Class 1)

RV-2-71G, Main Steam SafetyIRelief Valve (Low-Low Set) (Class 1)

RV-2-71H, Main Steam SafetyIRelief Valve (Low-Low Set) (Class 1)

ComponentISvstem Function The Nuclear Boiler System provides Reactor Pressure Vessel (RPV) overpressure protection by opening the SafetyIRelief Valves (SlRVs). The valves must open in order to prevent over pressurization of the reactor coolant system thereby preventing failure of the reactor system due to overpressure. The overpressure relief operation is self-actuated. The valves will open automatically or manually by the air operator during depressurization operation.

Certain valves are a designated part of the Automatic Depressurization System (ADS) and must open to provide automatic reactor depressurization as a result of a small break in the nuclear system coincidental with a failure of the High Pressure Coolant Injection (HPCI)

System. Rapid depressurization is necessary so that Low Pressure Coolant lnjection (LPCI) and the Core Spray systems can operate to protect the fuel cladding. ADS is automatically actuated after receipt of simultaneous Residual Heat Removal (RHR) or Core Spray pump running and low-low reactor water level signals.

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Monticello Nuclear Generating Plant Revision 0 Component/Svstem Function (Cont.)

In addition to the above, certain valves are designated as part of the SIRV Low-Low Set System and are set to open automatically at a set-point lower than the mechanical self-actuated set point to prevent the re-opening of a non-low-low set SIRV following a reactor isolation transient.

The set-points of the low-low set SIRVs ensure that they will be the first SIRVs to open and the last to close. After opening and closing of a low-low set SRV, a time delay relay prevents the operator or the low-low set logic from immediately re-opening the SIRV to allow the water leg in the SIRV discharge line to recede. The valves will open as part of the SRV Low-Low Set System in the event of a reactor SCRAM with reactor pressure greater than the low-low setpoint and the SRV low-low set hand switch in the auto position.

2. Applicable Code Edition and Addenda ASME OM Code-2004 Edition, with Addenda through OMb Code-2006.

3. Applicable Code Requirement(s1 Appendix I, Paragraph I-1320(a), 5-Year Test Interval, specifies that Class Ipressure relief valves shall be tested at least once every 5 years, starting with initial electric power generation. No maximum limit is specified for the number of valves to be tested within each interval; a minimum of 20% of the valves from each valve group shall be tested within any 24-month interval. This 20% shall consist of valves that have not been tested during the current 5-year interval, if they exist. The test interval for any individual valve shall not exceed 5 years.

4. Reason for Request MNGP transitioned from an 18-month fuel cycle to a 24-month fuel cycle on September 30, 2005 via Licensing Amendment No. 143. Prior to transitioning to the 24-month fuel cycle, ASME Code requirements could be satisfied by removing and testing approximately one-third of the 8 SIRVs each refueling outage in order to comply with the 5-year test interval requirements for Class 1 pressure relief valves imposed by the Code of record during that time. Since transitioning to the 24-month fuel cycle MNGP must remove at least one-half of the subject relief valves each refueling outage for off-site testing. The removal of approximately half of the 8 valves versus approximately a third of the valves each outage requires the removal of additional insulation, instrumentation, and other interferences. This additional work results in an undesirable increase in radiation exposure to maintenance personnel.

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Monticello Nuclear Generating Plant Revision 0

4. Reason for Request (Cont.1 The ASME Code committees have recently developed Code Case OMN-17, "Alternative Rules for Testing ASME Class 1 Pressure ReliefISafety Valves" which was published via ASME OM Code-2009 Edition. This Code Case has not been approved for use in US NRC Regulatory Guide

1. I 92, "Operation and Maintenance Code Case Acceptability, ASME OM Code, dated June 2003. The Code Case allows the Owner to extend the test frequencies for Class Ipressure relief valves to a 72-month (6-year) test interval providing all the requirements of the Code Case are satisfied.

The Code applicability specified in the Code Case is, in part, ASME OM Code 2001 Edition through the 2006 Addenda of Appendix I, Section I-1320. This is consistent with the Interval Code of record for MNGP.

MNGP currently meets or exceeds all the requirements specified in Code Case OMN-17.

5. Proposed Alternative and Basis for Use As an alternative to the Code required 5-year test interval per Appendix I, paragraph 1-1320(a), MNGP proposes that the subject Class 1 pressure relief valves be tested at least once every three refueling cycles (approximately 6 years172 months) with a minimum of 20% of the valves tested within any 24-month interval. This 20% would consist of valves that have not been tested during the current 72-month interval, if they exist.

The test interval for any individual valve would not exceed 72 months except that a 6-month grace period is allowed to coincide with refueling outages to accommodate extended shutdown periods.

After as-found set-pressure testing, the valves shall be disassembled and inspected to verify that parts are free of defects resulting from time-related degradation or service induced wear. As-left set-pressure testing shall be performed following maintenance and prior to returning the valve to service. Each valve shall have been disassembled and inspected prior to the start of the 72 month interval. Disassembly and inspection performed prior to the implementation of Code Case OMN-17 may be used.

The relief valve testing and maintenance cycle at MNGP consists of removal of the SRV complement requiring testing and transported to an off-site test facility. Upon receipt at the off-site facility the valves are subject to an as-found inspection and set pressure testing. Prior to the return of a complement of SRVs for installation in the plant, the valves are disassembled and inspected to verify that internal surfaces and parts are free from defects or service induced wear prior to the start of the next test interval. During this process, anomalies or damage are identified and dispositioned for resolution. Damaged or worn parts, springs, gaskets and Page 3 of 5

@ Xcel Energye Monticello Nuclear Generating Plant Revision 0 seals are replaced as necessary. The valve seats are relapped, if necessary. Following reassembly, the valve's set pressure is recertified.

This existing process is in accordance with ASME OM Code Case OMN-17 paragraphs (d) and (e).

MNGP has reviewed the as-found set point test results for all of the SRV's tested since 1996 as detailed in table 1. The average as-found set pressure is 1100.4 psig. MNGP did not have any as-found tests since

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1996 that exceeded the Technical Specifications as-found 33.2 psig acceptance criteria.

TABLE 1 Summary of As- Found Test Results of SRV Page 4 of 5

Xcel Energy' Monticello Nuclear Generating Plant Revision 0 MNGP submits that the proposed alternative of increasing the test interval for the subject Class Ipressure relief valves from 5 years to 3 fuel cycles (approximately 6 years172 months) would continue to provide an acceptable level of quality and safety while restoring the operational and maintenance flexibility that was lost when the 24-month fuel cycle created the unintended consequences of more frequent testing. This proposed alternative will continue to provide assurance of the valves' operational readiness and provides an acceptable level of quality and safety pursuant to 10CFR50.55a(a)(3)(i).

6. Duration of Proposed Alternative The proposed alternative identified in this relief request shall be implemented during the Fifth Ten Year IST Interval beginning September 1, 2012.

7. Precedents Perry Nuclear Power Plant, Docket No. 50-440, SER Date October 22, 2009, Safety Evaluation of Relief Requests for Third 10-Year Pump and Valve Inservice Testing Program (TAC Nos. ME0191 through ME0198)

(re: VR-6)

Nine Mile Point Nuclear Station, Docket No. 50-410, SER Date April 17, 2001, Safety Evaluation of the Alternative to ASME Code Regarding Inservice Testing of Main Steam SafetylRelief Valves, (TAC No. MB0290).

8. References Code C a s e OMN-17, Alternative Rules for Jesting ASME Class 1 Pressure RelieflSafety Valves Page 5 of 5