CNL-13-119, Revision to Watts Bar Nuclear Plant, Unit 1, Reactor Vessel Surveillance Capsule Withdrawal Schedule

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Revision to Watts Bar Nuclear Plant, Unit 1, Reactor Vessel Surveillance Capsule Withdrawal Schedule
ML13333A165
Person / Time
Site: Watts Bar Tennessee Valley Authority icon.png
Issue date: 11/22/2013
From: James Shea
Tennessee Valley Authority
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
CNL-13-119
Download: ML13333A165 (9)
v • d • e


Text

Tennessee Valley Authority, 1101 Market Street, Chattanooga, Tennessee 37402 CNL-13-119 November 22, 2013 10 CFR 50.4 10 CFR 50 Appendix H ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001 Watts Bar Nuclear Plant Unit 1 Facility Operating License No. NPF-90 NRC Docket No. 50-390

Subject:

Revision to Watts Bar Nuclear Plant, Unit 1, Reactor Vessel Surveillance Capsule Withdrawal Schedule

Reference:

1. "Materials Reliability Program: Coordinated PWR Reactor Vessel Surveillance Program (CRVSP) Guidelines (MRP-326)," EPRI, Palo Alto, CA dated December 2011
2. American Society for Testing and Materials (ASTM) E-1 85-82, "Standard Practice for Conducting Surveillance Tests for Light-Water Cooled Nuclear Power Reactor Vessels," dated July 1, 1982
3. NUREG-1 801, Revision 2, "Generic Aging Lessons Learned (GALL)

Report," dated December 2010

4. Administrative Letter 97-04, "NRC Staff Approval for Changes to 10 CFR Part 50, Appendix H, Reactor Vessel Surveillance Specimen Withdrawal Schedules," dated September 30, 1997 Pursuant to Title 10 of the Code of Federal Regulations (10 CFR), Part 50, Appendix H, "Reactor Vessel Material Surveillance Program Requirements," Paragraph III.B.3, the Tennessee Valley Authority (TVA) is requesting Nuclear Regulatory Commission (NRC) review and approval of the enclosed revision to the surveillance capsule removal schedule for Watts Bar Nuclear Plant (WBN), Unit 1. The proposed reactor vessel surveillance capsule removal schedule was developed to implement recommendations for WBN, Unit 1, in MRP-326 (Reference 1). MRP-326 addresses the need for reactor vessel property data at fluence values representative of 60 years of operation and beyond for WBN, Unit 1, and the industry. The requested change to the 10 CFR 50, Appendix H program for WBN, Unit 1, satisfies the requirements of 10 CFR 50, Appendix H and ASTM E-1 85-82 (Reference 2) and is consistent with the guidance of NUREG-1 801 (Reference 3).

Printed on recycled paper

U.S. Nuclear Regulatory Commission Page 2 November 22, 2013 The NRC Administrative Letter 97-04 (Reference 4) clarified the submittal requirements of 10 CFR 50, Appendix H. As stated in Administrative Letter 97-04, "...as long as the plant's withdrawal schedule change meets the applicable ASTM standard, the plant will not be exceeding the operating authority already granted in its license. Therefore, a license amendment would not be required, although prior NRC approval to verify conformance with the ASTM standard is required by 10 CFR 50, Appendix H." Because the proposed change described in the enclosure to this letter satisfies the requirements of ASTM E-185-82 (i.e.,

the applicable standard for WBN, Unit 1), TVA has determined that a license amendment is not required, and is consistent with the guidance of Administrative Letter 97-04.TVA requests NRC review and approval of the proposed withdrawal schedule.

This letter contains no new regulatory commitments. TVA requests that the NRC approve the proposed withdrawal schedule by March 14, 2014, to allow Reactor Vessel Surveillance Capsules V and Y to remain inserted in the core beyond the upcoming WBN, Unit 1, refueling outage scheduled to begin on March 24, 2014. Please address any questions regarding this request to Mr. Edward D. Schrull at 423-751-3850.

Resp ully, J. Shea Vic President, Nuclear Licensing

Enclosure:

Proposed Revision to the Watts Bar Nuclear Plant, Unit 1, Reactor Vessel Surveillance Program cc (Enclosure):

NRC Regional Administrator - Region II NRC Senior Resident Inspector - Watts Bar Nuclear Plant, Unit 1 Director, Division of Radiological Health - Tennessee State Department of Environment and Conservation

ENCLOSURE TENNESSEE VALLEY AUTHORITY WATTS BAR NUCLEAR PLANT UNIT I PROPOSED REVISION TO THE WATTS BAR NUCLEAR PLANT, UNIT 1, REACTOR VESSEL SURVEILLANCE PROGRAM

Subject:

Revision to Watts Bar Nuclear Plant, Unit 1, Reactor Vessel Surveillance Capsule Withdrawal Schedule

1.0 BACKGROUND

2.0 CURRENT PROGRAM /WITHDRAWAL SCHEDULE 3.0 CHANGES TO PROGRAM / WITHDRAWAL SCHEDULE 4.0 JUSTIFICATION 5.0 PRECEDENTS

6.0 REFERENCES

ATTACHMENTS

1. Current Watts Bar Nuclear Plant, Unit 1, Withdrawal Schedule
2. Proposed Watts Bar Nuclear Plant, Unit 1, Withdrawal Schedule Page E-1 of 7

1.0 BACKGROUND

Appendix H, "Reactor Vessel Material Surveillance Program Requirements," to Title 10 of the Code of Federal Regulations (10 CFR), Part 50, describes reactor vessel material surveillance program requirements. Paragraph III.B.3 of 10 CFR 50, Appendix H states that a proposed material withdrawal schedule must be submitted with a technical justification per 10 CFR 50.4, and approved prior to implementation.

NRC Administrative Letter 97-04 (Reference 1) clarified the submittal requirements of 10 CFR 50, Appendix H. As stated in Administrative Letter 97-04, "...as long as the plant's withdrawal schedule change meets the applicable American Society for Testing and Materials (ASTM) standard, the plant will not be exceeding the operating authority already granted in its license. Therefore, a license amendment would not be required, although prior NRC approval to verify conformance with the ASTM standard is required by 10 CFR 50, Appendix H." Because the proposed change described in the enclosure to this letter satisfies the requirements of ASTM E-185-82 (Reference 2) (i.e., the applicable standard for WBN, Unit 1), TVA has determined that a license amendment is not required, consistent with the guidance of Administrative Letter 97-04, and requests NRC review and approval of the proposed withdrawal schedule.

The nuclear industry has developed a Coordinated PWR Reactor Vessel Surveillance Program (CRVSP), which is documented in MRP-326, "Coordinated PWR Reactor Vessel Surveillance Program (CRVSP) Guidelines" (Reference 3). The purpose of the CRVSP is to increase the fluence levels of future surveillance capsules at withdrawal while maintaining compliance with 10 CFR 50, Appendix H, and consistent with the guidance of NUREG-1 801, Revision 2, "Generic Aging Lessons Learned (GALL) Report" (Reference 4). The CRVSP will result in the generation of high fluence pressurized water reactor surveillance data in support of nuclear power plant extended life operations.

The proposed changes to the WBN, Unit 1, reactor vessel surveillance capsule withdrawal schedule are required to allow Reactor Vessel Surveillance Capsules V and Y to remain inserted in the core beyond the upcoming WBN, Unit 1, refueling outage scheduled to begin on March 24, 2014, consistent with the MRP-326 guidelines for WBN, Unit 1.

2. CURRENT PROGRAM / WITHDRAWAL SCHEDULE Six surveillance capsules containing beltline materials fabricated from ASME SA-508 Class 2 (high Cu) and Grau Lo LW320 flux were inserted in the WBN, Unit 1, reactor prior to initial start-up. The current WBN, Unit 1, reactor vessel surveillance capsule withdrawal schedule is provided in Attachment 1 to this enclosure.

Four of the six surveillance capsules (i.e., U, W, X and Z) have been removed and tested. Capsules V and Y have a planned removal at 15 effective full power years (EFPY), at which time capsule V will be tested and capsule Y will be placed in storage.

Using the capsule lead factor and the linear relationship between the reported peak RPV fluences and their corresponding EFPY values, the capsule fluence at 15 EFPY was calculated to be 3.35x1019 neutrons per square centimeter (n/cm2). Capsules V and Y are currently scheduled to be removed during WBN, Unit 1 refueling outage U1C12, which is scheduled to begin on March 24, 2014.

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3. CHANGES TO PROGRAM I WITHDRAWAL SCHEDULE Attachment 2 to this enclosure provides the proposed revision to the WBN, Unit 1, reactor vessel surveillance capsule withdrawal schedule. TVA proposes to revise the WBN, Unit 1, reactor vessel surveillance capsule withdrawal schedule as follows:
  • Capsule V will be removed during the last scheduled refueling outage before estimated capsule exposure to a neutron fluence equal to two times the peak RPV neutron fluence at 60 years of operation (i.e., 54 EFPY). The removed capsule will then be tested.

The revised schedule is based on the recommendation for WBN, Unit 1, in MRP-326 and reflects calculated neutron fluence projections derived in WCAP-1 6760-NP (Reference 5). The proposed withdrawal schedule satisfies the requirements of ASTM E-1 85-82. Therefore, the withdrawal schedule satisfies the requirements of Appendix H to 10 CFR 50.

4. JUSTIFICATION The WBN, Unit 1, Reactor Vessel Irradiation Surveillance Program complies with ASTM E-185-82 and 10 CFR 50, Appendix H, with the exception that four of the six reactor vessel irradiation surveillance capsules will receive a fluence that is 3.6 times the maximum reactor vessel fluence (i.e., a lead factor of 3.6) rather than the required lead factor of 3.0. At the time of the design of the surveillance program, all capsules were positioned as near to the vessel wall as possible and were limited to a fluence less than 3.0 times the vessel fluence. A more accurate method of calculating vessel and capsule fluence was subsequently developed which results in a lead factor of 3.6 for four of the capsules. This difference is not considered to be of any significant consequence because the test results from the encapsulated specimens will represent the actual behavior of the material in the vessel. Therefore, the evaluation of the effects of radiation on the actual vessel material is not influenced by the larger lead factor.

MRP-326 states that the plant is responsible for determination of the actual removal year, based on the latest RPV fluence data. Following the guidance provided in MRP-326, the projected 2x60-year peak Reactor Vessel fluence and year of withdrawal were estimated. The latest Calculated Neutron Fluence and Future Fluence Projections were developed in WCAP-1 6760-NP. The projected 2x60 year peak Reactor Vessel fluence is 6.02x1 019 n/cm 2, which is twice the projected 60-year (54 EFPY) peak fluence of 3.01x10 19 n/cm 2 , reported in Table 6-2 of WCAP-16760-NP. Using the capsule lead factor and the linear relationship between the reported maximum fluence values and their corresponding EFPY values in WCAP-16760-NP Table 6-1, the EFPY required for Capsule V to reach 6.02x1 019 n\cm 2 was calculated to be 25.9. Assuming a 0.95 capacity factor starting in 2011 and the projected removal EFPY of 25.9, Capsule V should reach the specified fluence in 2024. As stated in Section 3 of this enclosure, the proposed schedule reflects the calculated neutron fluence projections derived in WCAP-16760-NP.

The proposed withdrawal schedule also requires that Capsule Y remain inserted in the reactor vessel on standby until needed to fulfill future 10 CFR 50, Appendix H or license renewal requirements. In the current withdrawal schedule, Capsule V and Capsule Y were to be removed after approximately 15 EFPY of operation, with one capsule being Page E-3 of 7

tested to satisfy the requirements of the fourth capsule (in a four-capsule withdrawal schedule) for extended operating life, while the other should be placed in storage pending regulatory guidance for capsule reinsertion. The proposed withdrawal schedule is consistent with NUREG-1801, Revision 2 (Reference 4),Section XI.M31, that recommends retaining additional capsules within the reactor vessel to support additional testing in the case that data from a required surveillance capsule is determined to be invalid, or in preparation for operation beyond 60 years.

This proposed change in the WBN, Unit 1, reactor vessel surveillance program capsule withdrawal schedule supports the goal of EPRI MRP-326 to coordinate the withdrawal schedules of remaining surveillance capsules so that pressurized water reactor high fluence surveillance data is available to develop future reactor vessel embrittlement trend curves.

5.0 PRECEDENTS The NRC has previously approved reactor vessel surveillance program capsule withdrawal schedules implementing the recommendations of MRP-326 for:

1. Shearon Harris Nuclear Plant [Safety Evaluation dated October 21, 2011 (Reference 6)]
2. H. B. Robinson Steam Electric Plant, Unit 2 [Safety Evaluation dated December 21, 2011 (Reference 7)]
3. Diablo Canyon Power Plant, Unit 1 [Safety Evaluation dated March 2, 2012 (Reference 8)]
4. Fort Calhoun Station, Unit 1 [Safety Evaluation dated January 31, 2013 (Reference 9)]
5. Seabrook Station, Unit 1 [Safety Evaluation dated June 13, 2013 (Reference 10)]
6. Turkey Point Nuclear Generating Unit Numbers 3 and 4 [Safety Evaluation dated September 4, 2013 (Reference 11)]

6.0 REFERENCES

1. Nuclear Regulatory Commission (NRC) Administrative Letter 97-04, "NRC Staff Approval for Changes to 10 CFR Part 50, Appendix H, Reactor Vessel Surveillance Specimen Withdrawal Schedules," dated September 30, 1997.
2. American Society for Testing and Materials (ASTM) E-185-82, "Standard Practice for Conducting Surveillance Tests for Light-Water Cooled Nuclear Power Reactor Vessels", dated July 1, 1982.
3. "Materials Reliability Program: Coordinated PWR Reactor Vessel Surveillance Program (CRVSP) Guidelines (MRP-326)," EPRI, Palo Alto, CA: December 2011, 1022872.
4. NUREG-1 801, Revision 2, "Generic Aging Lessons Learned (GALL) Report," dated December 2010.
5. Westinghouse WCAP-1 6760-NP,"Analysis of Capsule Z from the Tennessee Valley Authority Watts Bar Unit 1 Reactor Vessel Radiation Surveillance Program," dated November 2007.

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6. Shearon Harris Nuclear Plant - Safety Evaluation for Revision to Reactor Vessel Surveillance Capsule Withdrawal Schedule (TAC No. ME6998)," dated October 21, 2011 (ADAMS Accession Number ML11293A076).
7. NRC Letter "H. B. Robinson Steam Electric Plant, Unit No. 2 - Request for Revision to Reactor Vessel Material Surveillance Capsule Withdrawal Schedule (TAC No. ME7533)," dated December 21, 2011 (ADAMS Accession Number ML11349A026).
8. NRC Letter "Diablo Canyon Power Plant, Unit No. 1: Safety Evaluation for Request to Revise the Reactor Vessel Material Surveillance Program Withdrawal Schedule (TAC ME7615)," dated March 2, 2012 (ADAMS Accession Number ML120330497).
9. NRC Letter "Fort Calhoun Station, Unit 1 - Request for Approval of Proposed Changes to the Reactor Pressure Vessel Surveillance Capsule Withdrawal Schedules (TAC No. ME8219)," dated January 31, 2013 (ADAMS Accession Number ML13017A467).
10. NRC Letter "Seabrook Station, Unit 1 - Revision to Reactor Vessel Surveillance Capsule Withdrawal Schedule (TAC No. MF0669)," dated June 13, 2013 (ADAMS Accession Number ML13050A138).
11. NRC Letter "Turkey Point Nuclear Generating Units Nos. 3 and 4 - Review of Reactor Vessel Material Surveillance Program - Revised Surveillance Capsule Withdrawal Schedule (TAC Nos. ME9564 and ME9565)," dated September 4, 2013 (ADAMS Accession Number ML13191A090).

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Attachment I Current Watts Bar Nuclear Plant, Unit 1, Withdrawal Schedule Capsule Location Withdrawal Fluence(a)

Capsule (degrees) Lead Factor(a) EFPY (n/cm 2 U 56 5.00 1.2 4.47 x 1018 (b)

W 124 5.05 3.88 1.08 x 1 019(b)

X 236 5.03 6.63 1.71 x 1019(1)

Z 304 5.06 9.37 2.40 x 1019(b)

V 58.5 4.31 Mc) Standby Y 238.5 4.31 (c) Standby (a) Updated from Capsule Z dosimetry analysis.

(b) Plant Specific evaluation.

(c) Section X1.M31, "Reactor Vessel Surveillance," of NUREG 1801 states that any surveillance capsules that are left in the reactor vessel should provide meaningful metallurgical data. The NRC specifically states that anything beyond 60 years of exposure is not meaningful metallurgical data. Capsules "V" and "Y"can be removed after 12.1 EFPY (Capsule exposure equivalent to one times the projected 48 EFPY Peak Vessel Fluence of 2.66 x 1019 n/cm 2, E > 1.0 million electron volts (MeV)). It is recommended that these capsules be removed after approximately 15 EFPY of operation, with one capsule being tested to satisfy the requirements of the fourth capsule (in a four-capsule withdrawal schedule) for extended operating life, while the other should be placed in storage pending regulatory guidance for capsule reinsertion.

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Attachment 2 Proposed Watts Bar Nuclear Plant, Unit 1, Withdrawal Schedule (Changes shown as bold typeface)

Capsule Location Withdrawal Fluence Capsule (degrees) Lead Factor EFPY (n/cm 2)

U 56 5.00 1.2 4.47 x 101" W 124 5.05 3.88 1.08 x 1019 X 236 5.03 6.63 1.71 x 10' 9 Z 304 5.06 9.37 2.40 x 1019 V 58.5 4.31 25.9(a) 6.02 x 1019 Y 238.5 4.31 Standby(b) Standby (a) Capsule V will be removed during the last scheduled outage before estimated capsule exposure to a neutron fluence equal to two times the peak RPV neutron fluence at 60 years of operation (i.e., 54 EFPY).

(b) Capsule Y shall remain inserted in the reactor vessel on standby until needed to fulfill future 10 CFR 50, Appendix H or license renewal requirements.

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