ML23313A095
| ML23313A095 | |
| Person / Time | |
|---|---|
| Site: | Vogtle  |
| Issue date: | 11/16/2023 |
| From: | John Lamb NRC/NRR/DORL/LPL2-1 |
| To: | Southern Nuclear Operating Co |
| John Lamb, NRR/DORL/LPL2-1 | |
| Shared Package | |
| ML23313A094 | List: |
| References | |
| EPID L-2023-LRM-0097 | |
| Download: ML23313A095 (7) | |
Text
November 16, 2023
LICENSEE: Southern Nuclear Operating Company, Inc.
FACILITY: Vogtle Electric Generating Plant, Units 1 and 2
SUBJECT:
SUMMARY
OF NOVEMBER 7, 2023, OBSERVATION PRE-SUBMITTAL MEETING WITH SOUTHERN NUCLEAR OPERATING COMPANY, INC.,
REGARDING A PROPOSED LICENSE AMENDMENT REQUEST FOR VOGTLE ELECTRIC GENERATING PLANT, UNITS 1 AND 2 (EPID NO. L-2023-LRM-0097)
On November 7, 2023, an Observation meeting was held between the U.S. Nuclear Regulatory Commission (NRC) and representatives of Southern Nuclear Operating Company, Inc. (SNC, the licensee). The purpose of the meeting was for SNC to describe its plan to submit a license amendment request (LAR) for Vogtle Electric Generating Plant (Vogtle), Units 1 and 2.
SNC is proposing to submit an LAR to reduce the ultimate heat sink (UHS) mission times from 30 days to 22 days and utilize available makeup systems to meet the Regulatory Guide (RG) 1.27, Revision 3, Ultimate Heat Sink for Nuclear Power Plants, November 2015 (Agencywide Documents and Access M anagement System (ADAMS) Accession No. ML14107A411), requirement to replenish cooling water for use 30 days post-accident.
On October 24, 2023 (ML23297A195), the meeting was noticed on the NRC public webpage.
A list of attendees is provided as an Enclosure.
The NRC staff opened the meeting with introductory remarks and a roll call of the attendees.
The SNC representative discussed the following topics: (1) background, (2) proposed LAR, (3) evaluation, (4) precedent, and (5) schedule.
Prior to the meeting, SNC provided slides contained in ML23304A268. On November 7, 2023, SNC revised its presentation slides. The SNC representative presented the revised slides contained in ML23311A245.
SNC stated that it proposes to change the Vogtle, Units 1 and 2, licensing basis to allow both emergency diesel generators (EDGs) and nuclear service cooling water (NSCW) trains to run continuously after the first 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> post-accident and utilize the available water sources of well water and river water to replenish the NSCW basins. SNC proposes to change the UHS mission time from 30 days to 22 days, not shut down one EDG at the conclusion of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> as is the current practice, and to run both EDGs for the duration of 22 days.
The NRC staff asked SNC to explain the need for the proposed LAR. SNC stated that the proposed LAR is to correct an NRC violation. SNC provided the ADAMS Accession No. for the NRC Inspection Report.
By letter dated February 10, 2021 (ML21041A217), the NRC issued an inspection report titled, Vogtle Electric Generating Plant, Units 1 & 2 - Integrated Inspection Report 05000424/2020004 and 50000425/2020004 and Independent Spent Fuel Storage Installation Report 07201039/2020002.
The Vogtle, Units 1 and 2, Chapter 9, Auxiliary Systems, of the UFSAR, Revision 24 (ML22326A120), states, in part:
The ultimate heat sink for VEGP [Vogtle Electric Generating Plant] is the nuclear service cooling water (NSCW) towers. Two 100% capacity redundant NSCW towers are provided for each generating unit, one tower associated with each train of the NSCW system. Each NSCW tower consists of a basin which contains the ultimate heat sink water and an upper structure in which the NSCW heat loads are transferred to the atmosphere. The combined storage capacity of the two tower basins per unit will meet the intent of the short-term storage requirements without makeup in conformance with Nuclear Regulatory Commission (NRC) Regulatory Guide 1.27.
The heat removal requirement is greater for Unit 2 than for Unit 1 due to the larger spent fuel storage capacity of the Unit 2 pool. This results in some differences in the system performance and available inventory for each unit. The Unit 2 ultimate heat sink analyses envelope Unit 1. Therefore, all Unit 2 values are applicable to Unit 1. Case results are listed as a single value (applicable to Units 1 and 2). Unit 1 specific values are retained for historical purpose (cases 2, 4, and 5-see paragraph 9.2.5.2.4). For the power uprate, the governing design cases were reanalyzed (cases 1 and 3).
Originally five cases were analyzed for the ultimate heat sink analysis. They were:
- 1. Ultimate heat sink design, LOCA [loss-of-coolant accident] case (two-train operation post LOCA for 1 day followed by one-train operation for 29 days or until basin depletion) Units 1 and 2 (table 9.2.5-3);
- 2. Ultimate heat sink performance, post-LOCA (during two-train post-LOCA operation until basin depletion) Unit 1 (table 9.2.5-4)
[HISTORICAL];
- 3. Ultimate heat sink maximum temperature case (one-train operation post-LOCA until basin depletion) Units 1 and 2 (table 9.2.5-5);
- 4. Ultimate heat sink design, MSLB [main steam line break] accident case (two-train operation post-MSLB accident inside containment for 1 day followed by one-train operation for 29 days) Unit 1 (table 9.2.5-6) [HISTORICAL];
- 5. Ultimate heat sink performance, post MSLB accident (during one-train operation post-MSLB accident inside containment)
Unit 1 (table 9.2.5-7) [HISTORICAL].
The NRC staff asked if SNC reanalyzed the cases for this proposed LAR. SNC said that it reviewed the appropriate cases.
In its presentation, SNC cited an amendment to Palo Verde, dated June 14, 1995 (ML021710106), as a precedent. In addition, SNC cited NUREG-1137, Safety Evaluation Report related to the operation of Vogtle Electric Generating Plant, Units 1 and 2, June 1985 (ML091330626), in its presentation.
The NRC staff asked questions regarding the following:
What is causing the potential failure of the restart of the EDG?
Describe the problem with the EDG air start compressor.
Describe whether EDG air start receivers only start EDG or drain during operation.
Describe the use of the transfer pump between the two basins.
What SNC meant by the change in mission time from 30 days to 22 days?
Is there margin in the mission time of 22 days?
Does SNC take actions prior to 22 days?
When is the make-up started?
When would river water be established?
Are more wells needed to satisfy the UHS supply need (e.g., Grand Gulf extended power uprate)?
Are back-up supplies safety-related?
Does reliance on non-safety-related pumps introduce any changes to security controls?
Besides the transfer pump, are there other shared systems and components related to the proposed LAR?
How does the proposed LAR affect long-term cooling of containment and the reactor?
What is the environmental impact of the proposed LAR?
Were external hazards considered?
SNC said that it planned to submit the LAR in the first quarter of 2024, requesting completion within 12 months of the acceptance review and an implementation within 120 days.
There was one member of the public in attendance from the Nuclear Energy Oversight Project (NEOP). NEOP had comments/concerns regarding the following:
The licensee stated that one of the reasons for submitting the LAR to the NRC was because of a concern that the second EDG would not automatically start as required.
The licensee further stated that there was air leakage from the air-start supply as designed and that there was sufficient air-start supply for 5-attempts to start the EDG.
NEOP expressed a concern that there appears to be a licensing issue here where the licensees UFSAR and NRC regulations require that both EDGs be able to automatically
start during an emergency situation. The individual also questioned the fuel oil supply for such an extended period of operation of both EDGs.
On page 18 of the licensees slides, SNC states, in, part, that:
Updated analyses show that there is sufficient fuel oil to meet the 7-day requirement provided operator actions reduce electrical load on the EDGs. An EDG loading profile will need to be used to achieve the 7-day requirement, which will involve changes to operating procedures.
NEOP stated a concern that to the extent that the licensees operators would take actions to reduce the EDG electrical load, this causes concern about taking safety-related equipment off the power bus of the EDG since that is the basic function of the EDG to supply power to safety related equipment. The individual suggested that licensee does not appear to have adequately performed a fault-tree analysis to ascertain what safety-related equipment and/or systems would be adversely affected with the proposed LAR and whether taking safety-related equipment off the power bus would adversely affect the safety of the nuclear reactor.
The licensees proposed LAR reduces the RG 1.27 expectation that:
The capacity of the UHS should be sufficient to provide cooling for the time necessary to evaluate the situation and take corrective action. A period of 30 days is considered adequate for these purposes. In addition, procedures should be available for ensuring the continued capability of the UHS beyond 30 days.
NEOP expressed a concern that to the extent that the licensee would have only 22 days to evaluate an emergency situation and take corrective action, NEOP suggests that the licensees assumption may not be correct and could be nonconservative based on operational history of dealing with a nuclear emergency such as a LOCA or other such general emergency. NEOP notes here that the Three Mile Island, the Chernobyl, and Fukushima nuclear accidents all resulted in a reactor core melt-down which took the respective plant operators more than 30 days to evaluate and take corrective actions to protect the health and safety of the public and to protect the environment. NEOP stated that, in those events, the environment was not sufficiently protected from the release of radioactive particles.
The licensee stated that Well Water Makeup is normal makeup water for the NSCW and is provided by wells drilled into the Tuscaloosa aquifer, which has enough water yield capacity to meet the makeup requirements for emergency conditions. NEOP stated that the well water pumps are not powered by safety related buses; however, its power supplies are tied to Station Auxiliary Transformers (SATs). These SATs are connected to Plant Wilson, which can provide support through black start diesel generators to provide power to the Well Water pumps. NEOP stated a concern that to the extent that the licensee intends to draw make-up water from wells that incorporate pumps that are not connected to the safety related buses from Vogtle EDGs that the licensee cannot provide reasonable assurance that the requirements of RG 1.27 will be fully complied with and that power to the well pumps would be available on 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />s/7 days a week basis. NEOP questioned if the licensee meant that the EDGs at Plant Wilson would supply power or did the licensee mean that power from Plant Wilsons electric grid would
supply power? The NEOP representative expressed the view that any power source relied upon by the licensee to supply power to the well pumps must come from a safety-related power bus energized by EDGs that auto-start during an emergency situation.
NEOP expressed the view that the licensee should (1) be required to have operating procedures to address valve alignments and surveillance requirements, and (2) be required to address seismic concerns related to the wells and to Plant Wilson. Also, NEOP expressed concerns that the licensee (1) is departing from RG 1.27, (2) is departing from the licensees UFSAR, and (3) should consider installing a third EDG for the sole purpose of supplying make-up water from the wells and from the river as outlined in the proposed LAR.
The NRC staff made no regulatory decisions during the meeting. Once received, the NRC staff will perform a thorough review of the proposed LAR. The NRC staff will make any regulatory decisions in writing in a timely manner. Pub lic Meeting Feedback forms were available, but no comments were received.
The meeting adjourned at 12:17 pm Eastern Standard Time.
Please direct any inquiries to me at John.Lamb@nrc.gov or 301-415-3100.
/RA/
John G. Lamb, Senior Project Manager Plant Licensing Branch, II-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation
Docket Nos. 50-424 and 50-425
Enclosure:
List of Attendees
cc w/encls: Distribution via Listserv LIST OF ATTENDEES
NOVEMBER 7, 2023, PRE-SUBMITTAL MEETING WITH SOUTHERN NUCLEAR COMPANY
REGARDING A PROPOSED
LICENSE AMENDMENT REQUEST
VOGTLE ELECTRIC GENERATING PLANT, UNITS 1 AND 2
ATTENDEE REPRESENTING
John G. Lamb U.S. Nuclear Regulatory Commission (NRC)
Mike Markley NRC Andrea Johnson NRC Ahsan Sallman NRC Joshua Wilson NRC Donald Palmrose NRC Rao Tammara NRC Rick Scully NRC Gordon Curran NRC
DeLisa Pournaras Southern Nuclear Operating Company (SNC)
Ken Lowery SNC Amy Chamberlain SNC William Evans SNC Dennis Negron SNC Al Sweat SNC Elizabeth Sundstrom SNC
Kevin Kuhn Sargent and Lundy Nathan Jones Sargent and Lundy Jacob Whitely Sargent and Lundy Joshua Nikolovski Sargent and Lundy
Tom Saporito Public - Nuclear Energy Oversight Project
Enclosure
PKG: ML23313A094 Meeting Notice: ML23297A195 Meeting Summary: ML23313A095 Slides: ML23304A268 and ML23311A245 NRC-001 OFFICE NRR/DORL/LPL2-1/PM NRR/DORL/LPL2-1/LA NRR/DSS/SCPB/BC NAME JLamb KGoldstein (ABaxter for/) BWittick DATE 11/07/2023 11/13/2023 11/14/2023 OFFICE NRR/DORL/LPL2-1/BC NRR/DORL/LPL2-1/PM NAME MMarkley JLamb DATE 11/16/2023 11/16/2023