ML19277B908
| ML19277B908 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 10/07/2019 |
| From: | Richard Guzman Plant Licensing Branch 1 |
| To: | Stoddard D Dominion Energy Nuclear Connecticut |
| Guzman R | |
| References | |
| EPID L-2019-LLA-0177 | |
| Download: ML19277B908 (6) | |
Text
October 7, 2019 Mr. Daniel G. Stoddard Senior Vice President and Chief Nuclear Officer Dominion Nuclear Innsbrook Technical Center 5000 Dominion Boulevard Glen Allen, VA 23060-6711
SUBJECT:
MILLSTONE POWER STATION, UNIT NO. 2 SUPPLEMENTAL INFORMATION NEEDED FOR ACCEPTANCE OF REQUESTED LICENSING ACTION RE: EXTENSION OF TECHNICAL SPECIFICATION 3.8.1.1, A.C. SOURCES - OPERATING, ALLOWED OUTAGE TIME (EPID L-2019-LLA-0177)
Dear Mr. Stoddard:
By letter dated August 14, 2019 (Agencywide Documents Access and Management System Accession No. ML19234A111), Dominion Energy Nuclear Connecticut, Inc. (the licensee) submitted a license amendment request for the Millstone Power Station (Millstone), Unit No. 2.
The proposed license amendment would revise Technical Specification 3.8.1.1, A.C. Sources -
Operating, to add a permanent Required Action a.3 that would provide an option to extend the allowed outage time (AOT) from 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to 10 days for one inoperable offsite circuit.
In addition, the licensee proposed a one-time exception to the new proposed Required Action a.3 that would extend the AOT to 35 days for one inoperable offsite circuit. One-time use of the 35-day AOT would allow replacement of the Millstone, Unit No. 3, A reserve station service transformer, its associated equipment, and other 345 kV south bus switchyard components that are nearing the end of their dependable service life. This work is planned to take place no later than the fall 2023 outage (3R22) for Millstone, Unit No. 3.
The purpose of this letter is to provide the results of the U.S. Nuclear Regulatory Commission (NRC) staffs acceptance review of this amendment request. The acceptance review was performed to determine if there is sufficient technical information in scope and depth to allow the NRC staff to complete its detailed technical review. The acceptance review is also intended to identify whether the application has any readily apparent information insufficiencies in its characterization of the regulatory requirements or the licensing basis of the plant.
Consistent with Section 50.90 of Title 10 of the Code of Federal Regulations (10 CFR), an amendment to the license (including the technical specifications) must fully describe the changes requested, following, as far as applicable, the form prescribed for original applications.
Section 50.34 of 10 CFR addresses the content of technical information required. This section stipulates that the submittal address the design and operating characteristics, unusual or novel design features, and principal safety considerations.
D. Stoddard The NRC staff has reviewed your application and concluded that the information delineated in the enclosure to this letter is necessary to enable the staff to make an independent assessment regarding the acceptability of the proposed amendment request in terms of regulatory requirements and the protection of public health and safety and the environment.
In order to make the application complete, the NRC staff requests that Dominion Energy Nuclear Connecticut, Inc. supplement its application to address the information requested in the enclosure by October 23, 2019. This will enable the NRC staff to begin its detailed technical review. If the information responsive to the NRC staffs request is not received by the above date, the application will not be accepted for review pursuant to 10 CFR 2.101, and the NRC will cease its review activities associated with the application. If the application is subsequently accepted for review, you will be advised of any further information needed to support the staffs detailed technical review by separate correspondence.
The information requested and associated timeframe in this letter were discussed with Shayan Sinha and other members of your staff on October 3, 2019.
If you have any questions, please contact me at (301) 415-1030 or Richard.Guzman@nrc.gov.
Sincerely,
/RA/
Richard V. Guzman, Senior Project Manager Plant Licensing Branch I Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-336
Enclosure:
Supplemental Information Needed cc: Listserv
- by e-mail OFFICE NRR/DORL/LPL1/PM NRR/DORL/LPL3/LA NRR/DE/EEOB/BC*
NAME RGuzman LRonewicz DWilliams DATE 10/04/2019 10/04/2019 9/12/2019 OFFICE NRR/DORL/LPL1/BC*
NRR/DORL/LPL1/PM NAME JDanna RGuzman DATE 10/05/2019 10/07/2019
Enclosure SUPPLEMENTAL INFORMATION NEEDED LICENSE AMENDMENT REQUEST REGARDING EXTENSION OF TECHNICAL SPECIFICATION 3.8.1.1, A.C. SOURCES - OPERATING, ALLOWED OUTAGE TIME DOMINION ENERGY NUCLEAR CONNECTICUT, INC.
MILLSTONE POWER STATION, UNIT NO. 2 DOCKET NO. 50-336 By letter dated August 14,2019 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML19234A111), Dominion Energy Nuclear Connecticut, Inc. (DENC, the licensee) submitted a license amendment request (LAR) for the Millstone Power Station (Millstone), Unit No. 2. The proposed amendment would revise Technical Specification (TS) 3.8.1.1, A.C. Sources - Operating, to add a permanent Required Action a.3 that provides an option to extend the allowed outage time (AOT) from 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to 10 days for one inoperable offsite circuit. In addition, the licensee proposes a one-time exception to the new proposed Required Action a.3 that would extend the AOT to 35 days for one inoperable offsite circuit. One-time use of the 35-day AOT would allow replacement of the Millstone, Unit No. 3, A reserve station service transformer (RSST), its associated equipment, and other 345 kV south bus switchyard components that are nearing the end of their dependable service life. This work is planned to take place no later than the fall 2023 outage (3R22) for Millstone, Unit No. 3.
The licensee states in the LAR that the proposed changes have been deterministically evaluated in accordance with the guidance of NUREG-0800, Branch Technical Position (BTP) 8-8, Onsite (Emergency Diesel Generators) and Offsite Power Sources Allowed Outage Time Extensions, dated February 2012. Deviations from the deterministic criteria provided in BTP 8-8 that require supplemental risk information are supported by an evaluation consistent with Regulatory Guide (RG) 1.174, Revision 3, and RG 1.177, Revision 1.
Consistent with Section 50.90 of Title 10 of the Code of Federal Regulations (10 CFR), an amendment to the license (including the TSs) must fully describe the changes requested, following as far as applicable, the form prescribed for original applications. Section 50.34 of 10 CFR addresses the content of technical information required. This section stipulates that the submittal address the design and operating characteristics, unusual or novel design features, and principal safety considerations.
The U.S. Nuclear Regulatory Commission (NRC) staff performed an acceptance review of the LAR in accordance with the Office of Nuclear Reactor Regulation (NRR) Office Instruction LIC-109, Revision 2, Acceptance Review Procedures, dated January 16, 2017 (ADAMS Accession No. ML16144A521). The NRC staffs acceptance review was performed to determine if there is sufficient technical information in scope and depth to allow the NRC staff to complete its detailed technical review. The acceptance review is also intended to identify whether the application has any readily apparent information insufficiencies in its characterization of the regulatory requirements or the licensing basis of the plant.
The NRC staff has reviewed your application and determined that it is unacceptable for review with opportunity to supplement because it does not meet the criterion of Sufficiency of Information described in Section 3.1.2 of LIC-109. Specifically, it did not provide sufficient information concerning the proposed supplemental power source with adequate capacity to bring the plant to a cold shutdown. The staff concluded that the following information is necessary to enable the NRC staff to make an independent assessment regarding the acceptability of the proposed amendment in terms of regulatory requirements and the protection of public health and safety and the environment.
- 1. In Section 3.9 of the LAR, MPS2 FLEX Strategy, the licensee states that during the proposed permanent TS Required Action and one-time exception, DENC will utilize the FLEX diesel generators as a supplemental power source to the inoperable offsite power source. The technical evaluation to support this approach is provided in Section 4.0.
In Section 4.2 of the LAR, Supplemental Power Source (SPS) for Extended AOTs, the licensee states, DENC proposes to use the onsite 480 V FLEX diesel generators as the supplemental power source for the inoperable offsite circuit, to mitigate a postulated LOOP event. The FLEX diesel generators are selected as the supplemental power source because the MPS2 EDGs [emergency diesel generators] (which are the first line of defense) cannot be credited.
In Section 4.2.2 of the LAR, Initial Conditions - Electrical Power Configuration (for 10-Day/35-Day AOTs), the licensee lists as one of the initial conditions: FLEX 4160 V portable generators are stored offsite but are available for connection to MPS2 4160 V bus 24D.
In Section 4.3 of the LAR, Assessment Against Branch Technical Position 8-8, the licensee states the following:
Two 4160 V generators are stored offsite in the NSRC [National SAFER Response Center] storage facility. These 4160 V generators would be used (as requested) to allow operators to place the unit in cold shutdown, if the alternative actions are unable to restore power. Therefore, the intent of this criterion is met. []
The deployment of the 480 V FLEX diesel generator and re-powering 480 V bus 22F within the timeline described in Table 1-3 will allow operators (as directed by the appropriate FSG procedure) to restore power to recharge the battery prior to depletion and to maintain reactor coolant system inventory. However, the onsite 480 V FLEX diesel generator will be connected to MPS2 480 V bus 22F within 13 hours1.50463e-4 days <br />0.00361 hours <br />2.149471e-5 weeks <br />4.9465e-6 months <br /> rather than one hour [emphasis added]. Stripping of non-required DC [direct current] and vital 120 V instrument loads shows that battery life is extended to 29 hours3.356481e-4 days <br />0.00806 hours <br />4.794974e-5 weeks <br />1.10345e-5 months <br /> (Reference 1-37), well beyond the time battery charging will be restored via repowering 480 V bus 22F.
The staff finds that the application as submitted does not include information demonstrating that the proposed change meets the intent of the criteria identified in BTP 8-8. Specifically:
- a. The supplemental power source must demonstrate that it has enough capacity to carry all LOOP [loss-of-offsite power] loads to bring the unit to a cold shutdown without any load shedding.
- b. To support the one-hour time for making this power source available, plants must assess their ability to cope with loss of all AC [alternating current] power for one hour independent of an alternate alternating current (AAC) power source. The plant should have formal engineering calculations for equipment sizing and protection and have approved procedures for connecting the AAC or supplemental power sources to the safety buses.
Based on the above, the staff requests the licensee to provide technical justification to demonstrate how it meets the applicable criteria in BTP 8-8.
- 2. Additionally, the NRC staff noted the following items for the licensee to consider when evaluating its response to the above acceptance review items and supplementing its LAR as appropriate:
- a. The proposed TS markups do not discuss the compensatory measures and risk management actions taken during extended AOT. Since the NRC staffs review of the amendment considers the adequacy of compensatory measures and risk management actions, it is the staffs expectation that these items would be referenced in the TS markup.
- b. The LAR and the proposed TSs do not discuss information concerning the proposed actions to be taken, should severe weather conditions be anticipated prior to the scheduled transformer maintenance and replacement activities or if a severe thunderstorm warning or tornado warning is issued after entering TS Required Action a.3.
- c. The LAR states that the proposed activities for the permanent 10-day and the one-time 35-day offsite power AOT extensions are completed when Unit 3 is in Mode 5, 6, or defueled. However, the proposed Unit 2 TS markup does not indicate Unit 3 mode(s) for entry into Required Action a.3 of TS 3.8.1.1.
- d. In several instances, the LAR references NRC draft Revision 1 of BTP 8-8 dated March 2018, and provides discussion of how the proposed change meets the proposed draft staff positions. The NRC staff has not issued the revised BTP as approved guidance for generic use. While the NRC staffs safety evaluation of the LAR will consider the plant-specific justifications provided by the licensee, it will not be evaluated against a draft (unapproved) update to the generic guidance.
- e. In Tables 1-1 and 1-2 of the LAR, the licensee provided the duration (in days) for the various work/preventative maintenance activities and contingencies supporting both the proposed permanent 10-day and one-time 35-day AOTs. However, the licensee did not provide justification for the duration of the requested AOT (actual hours plus margin) based on plant-specific past operating experience.