ML21033A595
| ML21033A595 | |
| Person / Time | |
|---|---|
| Site: | Watts Bar  |
| Issue date: | 02/23/2021 |
| From: | Kimberly Green Plant Licensing Branch II |
| To: | Tennessee Valley Authority |
| Green K | |
| References | |
| EPID L-2021-LRM-0002 | |
| Download: ML21033A595 (6) | |
Text
February 23, 2021 LICENSEE: Tennessee Valley Authority FACILITY: Watts Bar Nuclear Plant, Unit 2
SUBJECT:
SUMMARY
OF JANUARY 21, 2021, TELECONFERENCE WITH TENNESSEE VALLEY AUTHORITY REGARDING PLANNED LICENSE AMENDMENT REQUESTS RELATED TO THE WATTS BAR NUCLEAR PLANT, UNIT 2 STEAM GENERATOR REPLACEMENT (EPID L-2021-LRM-0002)
On January 21, 2021, the U.S. Nuclear Regulatory Commission (NRC) staff conducted a Category 1 public teleconference with representatives of Tennessee Valley Authority (TVA).
The purpose of the teleconference was for TVA to discuss four planned license amendment requests (LARs) that are needed in support of the replacement steam generator (RSG) project at Watts Bar Nuclear Plant (Watts Bar), Unit 2.
The meeting notice and agenda, dated January 8, 2021, are available at Agencywide Documents Access and Management System (ADAMS) Accession No. ML21019A015. TVAs presentation slides for the meeting are available at ADAMS Accession No. ML21019A569. A list of participants is enclosed.
TVA initially planned to replace the steam generators (SGs) at Watts Bar, Unit 2, which have Alloy 600 mill annealed tubing with RSGs that have Alloy 690 thermally treated tubing during the Unit 2 fall 2023 refueling outage (U2R5). However, TVA has decided to move the replacement up to the spring 2022 refueling outage (U2R4), which is scheduled to begin in March 2022. The replacement SGs are currently on-site and are in protected storage. TVA stated that the planned LARs are similar in nature to those previously done for the Watts Bar, Unit 1 RSG project.
TVA plans to submit the LARs no later than March 1, 2021, and will request expedited NRC review and approval by February 1, 2022, to support the U2R4 outage.
TVA discussed each planned LAR. A summary of the four discussions is provided below.
WBN-TS-20 SG Tube Rupture (SGTR) Accident Dose Design Basis Change Installation of the RSGs will result in a revision to the primary and secondary side mass releases estimated for the SGTR accident. The primary side releases decrease, but the secondary side releases increase. These values are reflected in Updated Final Safety Analysis Report (UFSAR), Table 15.5-18. The reactor coolant system and SG volumes also increase.
TVA stated that NRC approval for the change to the licensing basis is needed because the increase in the main control room (MCR) thyroid dose for the pre-accident case exceeds the threshold in Nuclear Energy Institute (NEI) 96-07, Revision 1, Guidelines for 10 CFR 50.59 Implementation, i.e., the increase was greater than 10 percent of the difference between the
calculated value and the regulatory guideline limit. TVA noted that the SGTR accident doses remain less than dose limits in Part 100 of Title 10 of the Code of Federal Regulations (10 CFR), and General Design Criterion 19 of Appendix A to 10 CFR Part 50. The change in dose due to the SGTR will be reflected in UFSAR Table 15.5-9. The proposed changes to the UFSAR are detailed in TVAs slides.
The NRC staff asked if TVA considered using Regulatory Guide (RG) 1.195, Methods and Assumptions for Evaluating Radiological Consequences of Design basis Accidents at Light-Water Nuclear Power Reactors. TVA replied that its licensing basis is the Standard Review Plan, which references RG 1.4, Assumptions Used for Evaluating the Potential Radiological Consequences of a Loss of Coolant Accident for Pressurized Water Reactors. Therefore, to use RG 1.195 would require NRC approval.
WBN-TS-20 SG Water Level Changes for RSGs TVA plans to proposed changes to the narrow range SG water level required value in the Unit 2 Technical Specification (TS) limiting condition for operation (LCO) 3.4.7.b, and TS Surveillance Requirements (SRs) 3.4.5.2, 3.4.6.3, and 3.4.7.2. The SG water level value will change from 6 percent to 32 percent due to the change in SGs. The change in value is the same as the one made when the Unit 1 SGs were replaced. TVA noted that as an administrative change, it will propose to change the symbol and spell it out as greater than or equal to. TVAs slides detail the proposed changes to the TSs.
The NRC staff had no questions regarding this proposed LAR.
WBN-TS-20 SG Program Changes TVA plans to propose administrative changes to the SG Program descriptions contained in Unit 2, TSs 3.4.17, 5.7.2.12, and 5.9.9 to remove SG inspection and repair provisions (e.g.,
Generic Letter 95-05) that become invalid with the installation of the Unit 2 RSGs. Additionally, the allowance to use PAD4TCD to establish core operating limits will be proposed to be deleted from License Condition 2.C.(4) in the Unit 2 Operating License. With regard to the proposed change to License Condition 2.C.(4), TVA noted that the NRC staff is currently reviewing a LAR to use the Full Spectrum Loss-of-Coolant Accident (FSLOCA) for large-break and small-break LOCAs.
TVAs slides detail the proposed changes to the TSs and License Condition. During TVAs narrative about the proposed changes to TS 5.7.2.12.d.2, the NRC staff noted that Technical Specification Task Force (TSTF) Traveler 510 says that SG inspections should be conducted at least every 72 effective full power months or at least every third refueling outage. TVAs proposed wording for TS 5.7.2.12.d.2 states that the inspections should be conducted at least every 72 effective full power months and at least every refueling outage. Additionally, the NRC staff noted that based on TVAs proposed additional wording for TSTF Traveler 510, it does not consider the correction to TSTF Traveler 510 regarding applicable tube repair criteria. This phrase is not in the correction to TSTF Traveler 510. TVA stated that it will make the appropriate changes in the LAR to be consistent with TSTF Traveler 510.
With regard to License Condition 2.C.(4), the NRC staff inquired if TVA is transitioning to PAD5 for all accident analyses. TVA stated that the use of PAD5 will be coincident with the steam generator replacement, and that only the use of FSLOCA required NRC approval; the use of
PAD5 for the rest of the accident analyses will be carried out under the provisions of 10 CFR 50.59.
WBN-TS-20 Change to Unit 1 TS 3.7.12 for Continuous Opening of the Auxiliary Building Secondary Containment Enclosure (ABSCE) as a One-Time Exception TVA plans to propose a one-time exception to the Watts Bar, Unit 1 TS 3.7.12 Auxiliary Building Gas Treatment System (ABGTS) to allow administratively controlled openings of the ABSCE boundary on a continuous basis during the Unit 2 RSG Outage. TVA stated that it will use the same administrative controls that are currently allowed and used by the Unit 1, TS 3.7.12 for intermittent openings. These controls include closure of all ABSCE boundary openings within two minutes following notification from the MCR of an Auxiliary Building Isolation (ABI) alarm, thus ensuring closure of the ABSCE consistent with the safety analysis.
TVA explained that the ABGTS and the ABSCE that provides the ventilation envelope supporting ABGTS operability are shared between Watts Bar Unit 1 and Unit 2. The Watts Bar, TS 3.7.12 requires the ABGTS to be operable during Modes 1-4 for each unit. When Unit 2 shuts down for the RSG outage, it will exit the Unit 2, TS 3.7.12 operability requirements for ABGTS. However, due to the shared ABGTS and ABSCE boundary, the operability requirements of Unit 1 will still apply. During the RSG outage, when the Unit 2 equipment hatch is opened, the Unit 2 containment becomes an extension of the ABSCE boundary. The large flow of personnel and equipment in and out of the Unit 2 containment will be in excess of what is experienced during a typical refueling outage. The current wording of the Note in Unit 1, TS 3.7.12 limits passage through this boundary to intermittent openings. Due to this large flow of personnel and equipment, the ABSCE doors would be excessively cycled and could challenge the integrity of the doors over the course of the Unit 2 RSG outage. Therefore, there is a need for continuous versus intermittent opening of the ABSCE boundary at controlled access points during the Unit 2 RSG Outage. The subject access points involve three plant doors and the Unit 1 equipment hatch. A description of these access points and proposed one-time exception are detailed in TVAs slide presentation.
TVA further explained that in terms of ABSCE closure time capability, there is no difference between the control of intermittent ABSCE openings currently managed under Unit 1, TS 3.7.12 versus the control of continuous ABSCE openings proposed to be managed during the Unit 2 RSG outage. TVA has existing procedures, namely TI-65, by which the ABSCE openings will be continuously manned, and the operators will be in contact with the MCR such that the doors can be closed within the time requirements of the safety analysis. TVA noted that there is no direct precedent for a change from intermittent opening to a one-time exception for continuous opening of the ABSCE.
The NRC staff asked if there would be a limit on the number of openings of the four access points in the proposed footnote. TVA replied that TI-65 gives an area for the allowed opening with margin and that if this is exceeded, the access points have to be manned and closed no matter how many times the access points are opened. The NRC staff also asked if temporary doors or screens will be installed. TVA stated that a temporary door that can be automatically rapidly closed, and also be manually closed, if needed, will be installed for the equipment hatch.
The NRC noted that with continuous openings, one can lose track of the conditions of the doors, and asked TVA how does it plan to maintain track of the doors and their conditions to prevent deterioration of the doors. TVA stated that access is limited to four specific breaches in containment and that there are rigid processes in place to maintain the conditions of the doors.
No comments or public meeting feedback were received. No regulatory decisions were made at this meeting.
Please direct any inquiries to me at 301-415-1627 or by e-mail to Kimberly.Green@nrc.gov.
/RA/
Kimberly J. Green, Senior Project Manager Plant Licensing Branch II-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-391
Enclosure:
List of Participants cc: Listserv
LIST OF PARTICIPANTS JANUARY 21, 2021, TELECONFERENCE WITH TENNESSEE VALLEY AUTHORITY REGARDING WATTS BAR NUCLEAR PLANT, UNIT 2 PLANNED LICENSE AMENDMENT REQUESTS RELATED TO THE PLANNED STEAM GENERATOR REPLACMENT Name Organization Kim Green U.S. Nuclear Regulatory Commission (NRC)
Luke Haeg NRC Undine Shoop NRC Steve Bloom NRC Andy Johnson NRC Paul Klein NRC Greg Makar NRC John Parillo NRC Josh Borremeo NRC Rao Karipineni NRC Brian Wittick NRC Clint Ashley NRC Mathew Burton NRC David Pratt NRC Al Butcavage NRC Russ Wells Tennessee Valley Authority (TVA)
Gordon Williams TVA Tammy Sears TVA Anne Robinson-Givens TVA Bill Victor TVA Kim Hulvey TVA Dean Baker TVA Andy Taylor TVA Kasey Decker TVA Robert Brower TVA Robert Kirkpatrick TVA Jesse Baron TVA Brian Briody TVA Daniel Fox TVA Jeremy Mayo TVA Dave Lafever TVA Doug Pollock TVA Scott Carter TVA Mark Ceraldi Framatome Enclosure
ML21033A595 *via e-mail OFFICE NRR/DORL/LPL2-2/PM NRR/DORL/LPL2-2/LA NRR/DNLR/NCSG/BC* NRR/DSS/SCPB/BC*
NAME KGreen BAbeywickrama SBloom BWittick DATE 02/16/2021 02/12/2021 02/16/2021 02/16/2021 OFFICE NRR/DSS/STSB/BC* NRR/DORL/LPL2-2/BC* NRR/DORL/LPL2-2/PM NAME VCusumano UShoop KGreen DATE 02/17/2021 02/22/2021 02/23/2021