ML091900724

Safety Evaluation for Revision to Reactor Pressure Vessel Surveillance Capsule Withdrawal Schedules

ML091900724
Person / Time
Site:	South Texas
Issue date:	08/05/2009
From:	Thadani M Plant Licensing Branch IV
To:	Halpin E South Texas
Thadani, M C, NRR/DORL/LPL4, 415-1476
References
TAC ME1409, TAC ME1410
Download: ML091900724 (6)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 August 5, 2009 Mr. Edward D. Halpin Chief Nuclear Officer STP Nuclear Operating Company South Texas Project P. O. Box 289 Wadsworth, TX 77483 SUB~IECT: SOUTH TEXAS PROJECT 1 AND 2: SAFETY EVALUATION FOR REVISION TO REACTOR PRESSURE VESSEL SURVEILLANCE CAPSULE WITHDRAWAL SCHEDULES (TAC NOS. ME1409 AND ME1410)

Dear Mr. Halpin:

By letter dated August 13, 2008 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML082330456), STP Nuclear Operating Company (the licensee) submitted for U.S. Nuclear Regulatory Commission (NRC) staff review and approval of a request for revising the withdrawal schedules for the two reactor pressure vessel (RPV) surveillance capsules (both are identified as Capsule X) for South Texas Project (STP), Units 1 and 2. The purpose of the licensee's submittal was to postpone the capsule withdrawal dates for the two units by one refueling cycle so that the RPV capsule withdrawal schedules would not coincide with the schedules for replacement of the respective RPV heads. Under the proposed schedule, one capsule per unit will be withdrawn during refueling outages 1RE16 and 2RE15, for STP, Units 1 and 2, respectively.

Based on its review of the licensee's request, the NRC staff concludes that the proposed revision to withdrawal schedules for the STP, Units 1 and 2 capsules continues to meet the requirements of the American Society for Testing and Materials Standard E185-82, "Standard Practice for Conducting Surveillance Tests for Light-Water Cooled Nuclear Power Reactor Vessels," and Appendix H to Title 10 of Code of Federal Regulations Part 50, "Reactor Vessel Material Surveillance Program Requirements." Therefore, the NRC staff finds the proposed modified capsule withdrawal schedules for STP, Units 1 and 2 are acceptable. The NRC staff's safety evaluation is enclosed.

E. Halpin -2 If you have any questions, please contact me at 301-415-1476 or by email at mohan.thadani@nrc.gov.

Sincerely,

/?JId,eLla~2u~

Mohan C. Thadani, Senior Project Manager Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-498 and 50-499

Enclosure:

As stated cc w/encl: Distribution via Listserv

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION REACTOR VESSEL SURVEILLANCE CAPSULE WITHDRAWAL SCHEDULE REVISION FACILITY OPERATING LICENSE NOS. NPF-76 AND NPF-80 STP NUCLEAR OPERATING COMPANY, ET AL.

SOUTH TEXAS PROJECT, UNITS 1 AND 2 DOCKET NOS. 50-498 AND 50-499

1.0 INTRODUCTION

By letter dated August 13, 2008 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML082330456), STP Nuclear Operating Company (STPNOC or the licensee) submitted for the U.S. Nuclear Regulatory Commission (NRC) staff's review a request for revising the withdrawal schedules for two reactor pressure vessel (RPV) surveillance capsules (both are identified as Capsule X) for South Texas Project (STP), Units 1 and 2. The purpose of the licensee's submittal was to postpone the capsule withdrawal dates of the two units by one refueling cycle so that the RPV capsule withdrawal schedules would not coincide with the currently planned schedules for replacement of their RPV heads.

The next set of withdrawals is scheduled to occur during Unit 1 refueling outage 15 (1 RE15) and Unit 2 refueling outage 14 (2RE 14). Under the proposed schedule, one capsule per unit will be withdrawn during refueling outages 1RE16 and 2RE15, for STP, Units 1 and 2, respectively.

2.0 REGULATORY REQUIREMENTS The surveillance programs for STP, Units 1 and 2 were implemented to monitor the radiation induced changes in the mechanical and impact properties of the RPV materials. The surveillance programs were established in accordance with Appendix H to Title 10 of the Code of Federal Regulations Part 50 (10 CFR Part 50), "Reactor Vessel Material Surveillance Program Requirements." Appendix H to 10 CFR Part 50 requires licensees to monitor changes in the fracture toughness properties of ferritic materials in the RPV beltline region of light-water nuclear power reactors. The regulation states that the design of the surveillance program and the withdrawal schedule must meet the requirements of the edition of the American Society for Testing and Materials (ASTM) Standard E185, "Standard Practice for Conducting Surveillance Enclosure

-2 Tests for Light-Water Cooled Nuclear Power Reactor Vessels," that is current on the issue date of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code) to which the reactor vessel was purchased. Later editions of ASTM E185 may also be used including those editions through 1982 (ASTM E185-82). NUREG-1801, "Generic Aging and Lessons Learned (GALL) Report," provides additional guidance concerning the development of surveillance programs to accommodate the 60-year extended period of operation if license renewal is pursued. The RPV surveillance programs for STP, Units 1 and 2, are based on ASTM E185-73. However, their current surveillance capsule withdrawal schedules have been developed in accordance with ASTM E185-82.

3.0 TECHNICAL EVALUATION

The licensee's RPV surveillance programs for STP, Units 1 and 2, are based on the ASTM E185-73 standard, and the surveillance capsule withdrawal schedules are in accordance with ASTM E185-82. ASTM E185-82 recommends that a surveillance program provide three surveillance capsules if the predicted transitional temperature shift (~RTNDT) at vessel inside surface is less than 100 degrees Fahrenheit (OF). The licensee stated in the submittal that the STP, Units 1 and 2 surveillance programs fall into this category. The staff verified this based on a survey of the NRC's Reactor Vessel Integrity Database which indicated that the bounding

~RTNDT value for the STP, Units 1 and 2 beltline materials for 32 effective full power years (EFPYs) is approximately 58.5 of. So far, three capsules have been withdrawn from each STP RPV, and three capsules remain in each RPV.

The last withdrawn capsules have neutron fluence values equivalent to 33.84 EFPYs for the Unit 1 RPV and 30.93 EFPYs for the Unit 2 RPV, meeting the ASTM E185-73 requirement, and meeting effectively the ASTM E185-82 requirement for the equivalent vessel neutron fluence value for the last capsule of each STP unit. Hence, the staff agrees with the licensee that no further samples are needed to support the 40-year operation of STP, Units 1 and 2.

STPNOC has stated its intention to submit an application to extend the operating licenses for STP, Units 1 and 2, for an additional 20 years for a license renewal authorization for 60 years of operation. As such, each unit's Capsule X will qualify operation for 60 years, and the remaining two capsules from each unit will be kept as spares until a determination for disposal is made.

The estimated neutron fluence values for each Capsule X at the proposed withdrawal dates are 4.37 X 10 19 n/cm 2 (E > 1.0 million electron volts (MeV)) for Unit 1 and 4.18 X 1019 n/cm 2 (E > 1.0 MeV) for Unit 2, or equivalently, 59.04 EFPYs for the Unit 1 and Unit 2 RPVs. The irradiated RPV material information from each unit's Capsule X, which is the subject of the present submittal for capsule withdrawal schedule deferral, is intended to support the extended period of operation for STP, Units 1 and 2.

Based on the above, the staff has concluded that the proposed withdrawal schedules for Capsule X for each STP unit is consistent with 10 CFR Part 50, Appendix H requirements because it meets the ASTM E185-73 recommendation and effectively meets the ASTM E185-82 recommendation.

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4.0 CONCLUSION

Based on its review of the licensee's submittal, the NRC staff concludes that the proposed withdrawal schedules for the STP, Units 1 and 2 capsules continue to meet the requirements of the ASTM Standard E185-82, and Appendix H to 10 CFR Part 50 and is acceptable for implementation. The licensee must revise the material surveillance program capsule withdrawal schedule in the Updated Final Safety Analysis Report (Section 5.0 and Table 16.1-2) for STP, Units 1 and 2, with only changes approved in this safety evaluation.

The Commission has concluded, based on the considerations discussed above regarding the revised RPV materials surveillance capsule program withdrawal schedule, that: (1) there is reasonable assurance that the health and safety of the public will not be endangered by the revised withdrawal schedule, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the revised withdrawal schedule will not be inimical to the common defense and security or to the health and safety of the public.

In addition, the NRC staff finds that the revised withdrawal schedule for RPV material surveillance Capsule X, which is consistent with the current license for operation of 40 years, allows future RPV withdrawals of material surveillance capsules to obtain RPV data with estimated fluence values greater than 40 years. However, this safety evaluation does not provide a determination on the material surveillance program for any period of extended operation for STP, Units 1 and 2. The NRC staff will evaluate the applicability of the withdrawal schedule for the extended period of operation once the licensee has submitted a license renewal application.

Principal Contributor: S. Sheng Date: August 5, 2009

ML091900724 *SE memo dated OFFICE NRR/LPL4/PM NRRlLPL4/LA DCI/CVIB/BC NRR/LPL4/BC NRRlLPL4/PM NAME MThadani JBurkhardt MMitchell* MMarkley MThadani DATE 7/22/09 7/21/09 7/8109 8/5/09 8/5/09