ML081620005

Relief Request VRR-GGNS-2007-01 and -02, Alternative Inservice Test Requirement, Extension to ASME OM Code 5-Year IST Interval for Main Steam Safety Relief Valve

ML081620005
Person / Time
Site:	Grand Gulf
Issue date:	07/11/2008
From:	Balwant Singal NRC/NRR/ADRO/DORL/LPLIV
To:	Entergy Operations
Donohew J N, NRR/DORL/LPL4, 415-1307
References
TAC MD7757, TAC MD7758
Download: ML081620005 (11)

Text

July 11, 2008 Vice President, Operations Entergy Operations, Inc.

Grand Gulf Nuclear Station P.O. Box 756 Port Gibson, MS 39150

SUBJECT:

GRAND GULF NUCLEAR STATION, UNIT 1 - RELIEF REQUEST RELATED TO ALTERNATIVE TEST INTERVAL FOR MAIN STEAM SAFETY RELIEF VALVES (TAC NOS. MD7757 AND MD7758)

Dear Sir or Madam:

By letter dated January 8, 2008 (GNRO-2007/00076), Entergy Operations, Inc. (EOI), requested authorization to use an alternative to an inservice test (IST) requirement in the American Society of Mechanical Engineers Operation and Maintenance of Nuclear Power Plants Code (ASME OM Code). Relief Request (RR) Nos. VRR-GGNS-2007-01 and VRR-GGNS-2007-02 were submitted for Grand Gulf Nuclear Station, Unit 1 (GGNS). EOI submitted a supplemental letter dated May 13, 2008 (GNRO-2008/00035).

The two RRs involve an extension to the ASME OM Code 5-year test interval for the GGNS main steam safety relief valves (MSSRV). RR No. VRR-GGNS-2007-01 is for MSSRV 1B21-F041E where the 5-year test interval expired in August 2007 (before RR VRR-GGNS-2007-01 was submitted). The NRC staff does not approve relief requests once the basis for the relief request has expired. In other words, the provisions in Title 10 of the Code of Federal Regulations (10 CFR) Section 50.55a(a)(3) for authorizing alternatives to ASME OM Code requirements are no longer applicable in this case after the test interval had expired.

However, in reviewing RR VRR-GGNS-2007-01 in the application, the NRC staff can state that the provisions in 10 CFR 50.55a(a)(3) for authorizing relief would have been applicable for this RR, if it had been submitted prior to the expiration of the 5-year test interval.

Request No. VRR-GGNS-2007-02 is for the following two sets of 11 MSSRVs: (1) 6 valves numbered 1B21-F041D, 1B21-F041F, 1B21-F041K, 1B21-F047D, 1B21-F051B, and 1B21-F051F; and (2) 5 valves numbered 1B21-F041G, 1B21-F047C, 1B21-F047G, 1B21-F047L, and 1B21-F051C. The request is to extend the ASME OM Code 5-year test interval from (1) about December 2008 to refueling outage 17 (spring 2010) for the first set of 6 MSSRVs and (2) about September 2010 (four valves) or January 2012 (one valve) to refueling outage 18 (winter 2012) for the second set of 5 MSSRVs. Therefore, the requested extension intervals range from 16 to 18 months, except for the one valve in the second set where the requested extension interval is only one month.

Based on the enclosed safety evaluation, the NRC staff has determined that authorizing the relief requested for these valves in RR VRR-GGNS-2007-02 pursuant to 10 CFR 50.55a(a)(3)(ii) is authorized by law and will not endanger life or property or the common defense and security, and is otherwise in the public interest giving due consideration to the burden upon the licensee that could result if the requirements were imposed on the facility. Based on this determination,

the alternative is authorized (1) for MSSRVs numbered 1B21-F041K, 1B21-F041F, 1B21-F051F, 1B21-F051B, 1B21-F041D, and 1B21-F047D through May 4, 2010 (in refueling outage 17); and (2) for MSSRVs numbered 1B21-F047L, 1B21-F041G, 1B21-F047G, 1B21-F051C, and 1B21-F047C through February 25, 2012 (in refueling outage 18).

Sincerely,

/RA/

Balwant K. Singal, Acting Chief Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-416

Enclosure:

Safety Evaluation cc w/encl: See next page

ML081620005 OFFICE NRR/LPL4/PM NRR/LPL4/LA DCI/CPTB/BC OGC NRR/LPL4/BC(A)

NAME JDonohew JBurkhardt JMcHale RHolmes BSingal DATE 7/8/08 6/16/08 05/22/08 07/07/08 7/11/08 Grand Gulf Nuclear Station (6/10/2008) cc:

Senior Vice President Office of the Governor Entergy Nuclear Operations State of Mississippi P.O. Box 31995 Jackson, MS 39201 Jackson, MS 39286-1995 Attorney General Vice President, Oversight Department of Justice Entergy Nuclear Operations State of Louisiana P.O. Box 31995 P.O. Box 94005 Jackson, MS 39286-1995 Baton Rouge, LA 70804-9005 Senior Manager, Nuclear Safety President

& Licensing Claiborne County Entergy Nuclear Operations Board of Supervisors P.O. Box 31995 P.O. Box 339 Jackson, MS 39286-1995 Port Gibson, MS 39150 Senior Vice President Richard Penrod, Senior Environmental

& Chief Operating Officer Scientist/State Liaison Officer Entergy Operations, Inc. Office of Environmental Services P.O. Box 31995 Northwestern State University Jackson, MS 39286-1995 Russell Hall, Room 201 Natchitoches, LA 71497 Associate General Counsel Entergy Nuclear Operations Chief, Energy and Transportation Branch P.O. Box 31995 Environmental Compliance and Jackson, MS 39286-1995 Enforcement Division Mississippi Department of Environmental Manager, Licensing Quality Entergy Operations, Inc. P.O. Box 10385 Grand Gulf Nuclear Station Jackson, MS 39289-0385 P.O. Box 756 Port Gibson, MS 39150 Regional Administrator, Region IV U.S. Nuclear Regulatory Commission State Health Officer 612 E. Lamar Blvd., Suite 400 State Health Board Arlington, TX 76011-4125 P.O. Box 1700 Jackson, MS 39215 Senior Resident Inspector U.S. Nuclear Regulatory Commission Attorney General P.O. Box 399 Asst. Attorney General Port Gibson, MS 39150 State of Mississippi P.O. Box 22947 Jackson, MS 39225-2947

SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION REQUEST NO. VRR-GGNS-2007-2 ALTERNATIVE TEST INTERVAL FOR MAIN STEAM SAFETY RELIEF VALVES ENTERGY OPERATIONS, INC.

GRAND GULF NUCLEAR STATION, UNIT 1 DOCKET NO. 50-416

1.0 INTRODUCTION

By letter dated January 8, 2008 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML080080589), Entergy Operations, Inc. (the licensee), requested authorization to use an alternative to an inservice test (IST) requirement in the 2001 Edition through 2003 Addenda of the American Society of Mechanical Engineers Operation and Maintenance of Nuclear Power Plants Code (ASME OM Code). The licensee submitted Request No. VRR-GGNS-2007-02 for Grand Gulf Nuclear Station, Unit 1 (GGNS). The licensee also submitted the supplemental letter dated May 13, 2008 (ADAMS Accession No. ML081350061), in response to a Nuclear Regulatory Commission (NRC) request for additional information for RR VRR-GGNS-2007-02 in a letter dated March 14, 2008 (ADAMS Accession No. ML080710001).

Request No. VRR-GGNS-2007-02 is for the following two sets of 11 main steam safety relief valves (MSSRVs): (1) 6 valves numbered 1B21-F041D, 1B21-F041F, 1B21-F041K, 1B21-F047D, 1B21-F051B, and 1B21-F051F; and (2) 5 valves numbered 1B21-F041G, 1B21-F047C, 1B21-F047G, 1B21-F047L, and 1B21-F051C. The request is to extend the ASME OM Code 5-year test interval from (1) about December 2008 to refueling outage 17 (spring 2010) for the first set of 6 MSSRVs and (2) about September 2010 (four valves) or January 2012 (one valve) to refueling outage 18 (winter 2012) for the second set of 5 MSSRVs. Therefore, the requested extension intervals range from 16 to 18 months, except for the one valve in the second set where the requested extension interval is only one month.

The licensee stated that the 2001 Edition through 2003 Addenda of the ASME OM Code is the current Code of record for the GGNS IST program.

2.0 REGULATORY EVALUATION

Section 50.55a(f), "Inservice testing requirements," of Title 10 to the Code of Federal Regulations (i.e., 10 CFR 50.55a(f)), requires, in part, that ASME Code Class 1, 2, and 3 components must meet the requirements of the ASME OM Code and applicable addenda, except where alternatives have been authorized by the Director of the Office of Nuclear Reactor Regulation pursuant to 10 CFR 50.55a(a)(3)(ii). The authorization of the relief request pursuant

to 10 CFR 50.55a(a)(3)(ii) would be that the applicant has demonstrated that compliance with the specified requirements would result in "hardship or unusual difficulty without a compensating increase in the level of quality and safety."

3.0 RR NO. VRR-GGNS-2007-02 3.1 Description of RR The licensee proposed an alternative in accordance with 10 CFR 50.55a(a)(3)(ii) to the 5-year test requirement in Mandatory Appendix I, Requirements for Inservice Testing of Nuclear Power Plant Pressure Relief Devices, Section I-1320, Test Frequencies, Class 1 Pressure Relief Valves, Paragraph (a), 5-Year Test Interval, of the 2001 Edition through 2003 Addenda of the ASME OM Code. The proposed alternative involves an extension to the ASME OM Code 5-year test interval requirement to reach (1) the spring 2010 (refueling outage 17) for six MSSRVs and (2) the winter 2012 (refueling outage 18) for five MSSRVs. See the table below. The next refueling outage for GGNS is the upcoming fall 2008 (refueling outage 16).

The 5-year test interval is for a test of each valve to open at the pressures bounded by the plant safety analysis. The licensee is proposing an alternative to the Code-required test interval, not an alternative to the test itself.

In Table 1 to the application, the licensee gave, for each of the 11 valves, the last test date, the scheduled replacement date to remove the valve in a refueling outage for testing, and the requested extension interval to the Code 5-year test interval. These are given below with the calculated date for the next testing of each valve:

Calculated Date for Next Test (with Requested requested interval Scheduled Valve Last Test Date Interval Extension extension) Replacement Date 1B21-F041K 01/09/2004 16 months 05/09/2010 04/18/2010 1B21-F041F 12/05/2003 17 months 05/05/2010 04/18/2010 1B21-F051F 12/04/2003 17 months 05/04/2010 04/18/2010 1B21-F051B 12/15/2003 17 months 05/15/2010 04/18/2010 1B21-F041D 01/09/2004 16 months 05/09/2010 04/18/2010 1B21-F047D 01/09/2004 16 months 05/09/2010 04/18/2010 1B21-F047L 01/25/2007 1 month 02/25/2012 02/19/2012 1B21-F041G 09/13/2005 18 months 03/13/2012 02/19/2012 1B21-F047G 09/20/2005 18 months 03/20/2012 02/19/2012 1B21-F051C 09/15/2005 18 months 03/15/2012 02/19/2012 1B21-F047C 09/20/2005 18 months 03/20/2012 02/19/2012 The calculated date for the next test (the fourth column) is calculated by adding the 5-year interval allowed by the Code plus the requested interval extension (third column) to the date of the last test (second column). The time interval, between (1) the calculated date for the next test and (2) the scheduled replacement date to remove the valve, ranges from as few as 6 days for

Valve 1B21-F047L above, to as many as 29 days for Valve 1B21-F047C above. The scheduled replacement dates are to show the removal of the valves in either refueling outage 17 (April 18, 2010) or refueling outage 18 (February 19, 2012). The valves are removed in the specified outage and tested before the outage is over.

The licensee is requesting authorization of the proposed alternative because compliance with this ASME OM Code requirement would result in a hardship due to unnecessary personnel radiation exposure, without a compensating increase in the level of quality or safety. The NRCs findings, with respect to the proposed extension to the ASME OM Code 5-year test interval requirement, are given below.

3.2 Technical Evaluation of VRR-GGNS-2007-2 Each refueling outage, a number of MSSRVs are removed from the steam lines and replaced by spare valves. The spare valves have already been tested, and the testing of the valves removed is performed during the refueling outage to determine if additional valves must be removed in the outage for testing. The valves removed are then refurbished and stored for a future refueling outage.

The licensee stated that its practice was to begin the ASME OM Code 5-year test interval when an MSSRV was installed and not to include the storage time for an MSSRV in meeting the Code-required 5-year test interval. However, the ASME OM Code requires that the 5-year test interval begin when the MSSRV is tested and include any storage time (i.e., the Code does not allow the valve storage time to extend the test interval). Therefore, the licensee is revising the MSSRV test schedule to comply with the ASME OM Code 5-year requirement for the test-to-test interval.

The licensee is proposing to test the 11 MSSRVs listed in Section 3.1 of this safety evaluation in the following two refueling outages:

1. Test MSSRVs 1B21-F041K, 1B21-F041F, 1B21-F051F, 1B21-F051B, 1B21-F041D, and 1B21-F047D during the refueling outage scheduled for the spring of 2010 instead of the upcoming refueling outage scheduled to begin in the Fall of 2008.

2. Test MSSRVs 1B21-F047L, 1B21-F041G, 1B21-F047G, 1B21-F051C, and 1B21-F047C during the refueling outage scheduled for the winter 2012 instead of the refueling outage scheduled to begin in the spring 2010.

There are a total of 20 MSSRVs that are located on each of the main steam lines between the reactor vessel and the first isolation valve within the drywell. They are tested to open at the pressures bounded by the plant accident analysis and have to be tested when the plant is shut down, which is during a refueling outage. The valves are removed from the main steam lines and tested in a refueling outage when the plant is shut down and the MSSRVs are not required to be operable. These tests are part of the required IST program of valves at GGNS.

3.2.1 ASME OM Code Requirement ASME OM Code Mandatory Appendix I, Section I-1320(a) of the 2001 Edition through 2003 Addenda of the ASME OM Code requires that Class 1 pressure relief valves (e.g., these GGNS MSSRVs) be tested at least once every 5 years.

3.2.2 Licensees Basis for Alternative In its application and supplemental letter, the licensee proposed to delay the removal and testing of the 11 MSSRVs because it would be a hardship due to unnecessary personnel radiation exposure, without a compensating increase in the level of quality or safety to remove and test more than 6 to 8 MSSRVs during a refueling outage. The licensee's normal practice at GGNS is to remove and test 6 to 8 MSSRVs every refueling outage, so that all 20 MSSRVs are removed and tested every three refueling outages.

The MSSRVs removed from service are tested, refurbished, retested, and may be placed in storage before being reinstalled during a future refueling outage. The MSSRVs removed for testing are immediately replaced by a valve from storage and are tested before the end of the outage because any failures in the testing may require additional valves to be removed and tested.

Crews of up to five to seven workers are required to remove each inservice MSSRV and install each spare MSSRV. Insulation and appurtenances on the MSSRV also require removal and reinstallation. The location of the MSSRVs in the containment results in radiation exposure to the maintenance personnel performing the work. The removal of additional MSSRVs beyond the six to eight MSSRVs that are normally removed during the upcoming refueling outage scheduled for the fall 2008 would add approximately 5.2-person roentgen equivalent man to the radiation exposure to the refueling outage without a compensating increase in the level of quality or safety. Without NRC authorization of the alternative, the additional work during the upcoming refueling outage scheduled for the fall 2008 would be contrary to the principles of keeping radiation exposure as low as is reasonably achievable (ALARA), as required by 10 CFR 20.1101.

In its application and supplemental letter, the licensee stated that it should be acceptable to extend the Code-required maximum test interval beyond 5 years based on satisfactory performance of the MSSRVs during IST. The IST history for MSSRVs installed for 54 months at GGNS from 2001 to the present indicates that 32 of 33 total tests have successfully passed the ASME OM Code as-found acceptance criterion of +/- 3 percent of set pressure. The as-found test for the one MSSRV that lifted outside of the +/- 3 percent test tolerance was in the negative, or conservative direction. The MSSRV lifted 3.5 percent below its set pressure. Additionally, the licensee stated that the GGNS test data is consistent with reliable and consistent performance of the same model valves (i.e., Dikkers Model G-471 valves) at Clinton Power Station and Perry Nuclear Power Plant.

3.2.3 Proposed Alternative Test In its letters, the licensee has proposed to extend the test interval for MSSRVs 1B21-F041K, 1B21-F041F, 1B21-F051F, 1B21-F051B, 1B21-F041D, 1B21-F047D, 1B21-F047L, 1B21-F041G, 1B21-F047G, 1B21-F051C, and 1B21-F047C beyond 5 years on a one-time basis. The requested interval extension for the MSSRVs varies between 1 to 18 months beyond the ASME OM Code test-to-test 5-year interval. All of these MSSRVs were refurbished, tested, and placed in storage for 2 to 22 months prior to installation in GGNS. The MSSRVs are scheduled to be removed after being in-service for 55 to 59 months.

The licensee is proposing to remove and test MSSRVs 1B21-F041K, 1B21-F041F, 1B21-F051F, 1B21-F051B, 1B21-F041D, and 1B21-F047D during the refueling outage scheduled for the spring 2010. Therefore, the test interval for these MSSRVs will expire up to 17 months prior to the refueling outage scheduled for the spring 2010. In its application, the licensee stated that the last test date for these valves is the following: January 9, 2004, December 5, 2003, December 4, 2003, December 15, 2003, January 9, 2004, and January 9, 2004, respectively.

The licensee is proposing to remove and test MSSRVs 1B21-F047L, 1B21-F041G, 1B21-F047G, 1B21-F051C, and 1B21-F047C during the refueling outage scheduled for the winter 2012. These valves were tested later than the valves listed in the previous paragraph.

The test interval for these MSSRVs will expire up to 18 months prior to the refueling outage scheduled for the winter 2012. In its application, the licensee stated that the last test date for these valves is the following: January 25, 2007, September 13, 2005, September 20, 2005, September 15, 2005, and September 20, 2005, respectively.

Based on the data in Table 1 of the application, the last test date and the requested interval extension (beyond the automatic 1-year extension of the Code, the licensee is requesting the extension to perform the Code-required test in refueling outages 17 or 18 after the plant is shut down and the MSSRVs are not required to be operable.

3.2.4 NRC Staffs Evaluation of Alternative Testing Interval The NRC staff has reviewed the MSSRV test results provided by Entergy to determine if it is acceptable to extend the test interval for MSSRVs 1B21-F041K, B21-F041F, 1B21-F051F, 1B21-F051B, 1B21-F041D, 1B21-F047D, 1B21-F047L, 1B21-F041G, 1B21-F047G, 1B21-F051C, and 1B21-F047C beyond the 5-year interval specified in the ASME OM Code.

The test results demonstrate that the MSSRVs almost always passed the TS lift acceptance criterion of +/- 3 percent of set pressure. In one instance, an unsatisfactory test was only slightly below +/- 3 percent of set pressure.

In its application and supplemental letter, the licensee stated that the MSSRVs were stored in a controlled environment from 2 to 22 months prior to installation, and will have been in service for up to 59 months prior to removal during the refueling outages scheduled for the spring 2010 and the winter 2012. The licensee also stated that stored MSSRVs are packaged to prevent condensation and corrosion. It provided the results for 16 tests for MSSRVs that were stored and then placed into service. The set pressure drift was insignificant in 15 of the 16 tests.

The licensee also stated that the MSSRVs were refurbished to a like-new condition prior to being placed in storage. In-house technicians perform testing, inspection, and refurbishment of each MSSRV that is removed from service in accordance with an approved procedure. The procedure identifies the critical components that are required to be inspected for wear and defects, and the critical dimensions that are required to be measured during the inspection.

Components found to be worn or outside of specified tolerances are either reworked to within the specified tolerance or replaced.

Based on the above evaluation, the NRC staff finds that the proposed alternative to extend the test interval for beyond the ASME OM Code 5-year test requirement for MSSRVs 1B21-F041K, 1B21-F041F, 1B21-F051F, 1B21-F051B, 1B21-F041D, 1B21-F047D, 1B21-F047L, 1B21-F041G, 1B21-F047G, 1B21-F051C, and 1B21-F047C is acceptable. Although the ASME OM Code does not require the MSSRVs to be routinely refurbished, refurbishment of MSSRV prior to installation provides reasonable assurance that set pressure drift will be minimized. The test results demonstrate that the MSSRVs almost always successfully passed the TS lift set pressure acceptance criterion of +/- 3 percent of set pressure. In one instance, the MSSRVs set pressure drifted slightly downward; not upward. From an overpressure protection standpoint, set pressure drift in the downwards direction is conservative because the valve would tend to open sooner than required. Test results also demonstrate that storage conditions did not adversely affect set pressure.

In its application, the licensee addressed not testing any of the above 11 MSSRVs in the upcoming refueling outage 16, which begins in the fall 2008. The licensee stated that during this refueling outage it will be replacing and testing 6 MSSRVs, at the restart from the outage the 11 MSSRVs will still be within the Code-required 5-year test-to-test interval, and the proposed test schedule is consistent with the licensee's historical method for implementing code requirements (i.e., the valves will have been installed for less than or equal to three operating cycles). Since the licensees plan to test about 17 MSSRVs in refueling outages 16, 17, and 18 is consistent with the licensee's normal practice of removing and testing 6 to 8 MSSRVs every refueling outage, so that all 20 MSSRVs are tested every three refueling outages, the NRC staff concludes that having the 11 MSSRVs in the RR tested in refueling outages 17 and 18, and not in refueling outage 16, is acceptable.

3.3 Conclusion Based on the letters submitted by the licensee and the evaluation given above, the NRC staff has concluded that compliance with ASME OM Code 5-year test interval for GGNS Unit 1 MSSRVs 1B21-F041K, B21-F041F, 1B21-F051F, 1B21-F051B, 1B21-F041D, 1B21-F047D, 1B21-F047L, 1B21-F041G, 1B21-F047G, 1B21-F051C, and 1B21-F047C would result in hardship due to unnecessary personnel radiation exposure. The additional time beyond that required by the ASME OM Code should not impair the valves operational readiness.

The NRC staff has determined that authorizing the relief requested for these valves in RR VRR-GGNS-2007-02 pursuant to 10 CFR 50.55a(a)(3)(ii) is authorized by law and will not endanger life or property or the common defense and security, and is otherwise in the public interest giving due consideration to the burden upon the licensee that could result if the requirements were imposed on the facility. Based on this, the alternative is authorized for MSSRVs 1B21-F041K, 1B21-F041F, 1B21-F051F, 1B21-F051B, 1B21-F041D, and

1B21-F047D through May 4, 2010 (in refueling outage 17) and for MSSRVs 1B21-F047L, 1B21-F041G, 1B21-F047G, 1B21-F051C, and 1B21-F047C through February 25, 2012 (in refueling outage 18).

Principal Contributor: S. Tingen Date: