ML23272A182
| ML23272A182 | |
| Person / Time | |
|---|---|
| Site: | Vogtle  |
| Issue date: | 10/11/2023 |
| From: | John Lamb NRC/NRR/DORL/LPL2-1 |
| To: | Southern Nuclear Operating Co |
| References | |
| EPID L-2023-LRQ-0004 | |
| Download: ML23272A182 (1) | |
Text
October 11, 2023 LICENSEE: Southern Nuclear Operating Company, Inc.
FACILITY: Vogtle Electric Generating Plant, Units 3 and 4
SUBJECT:
SUMMARY
OF SEPTEMBER 28, 2023, OBSERVATION PRE-SUBMITTAL MEETING HELD WITH SOUTHERN NUCLEAR OPERATING COMPANY, INC.,
REGARDING A PROPOSED LICENSE AMENDMENT REQUEST FOR VOGTLE ELECTRIC GENERATING PLANT, UNITS 3 AND 4 (EPID NO. L-2023-LRQ-0004)
On September 28, 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 3 and 4.
SNC is proposing to revise Technical Specifications (TS) 3.7.6, Main Control Room Emergency Habitability System (VES). The proposed LAR will revise the Vogtle, Units 3 and 4, Combined License (COL) Appendix A, TS 3.7.6:
Surveillance Requirement (SR) 3.7.6.5 to refer to the American National Standards Institute (ANSI) / Compressed Gas Association (CGA) Commodity Specification for Air, G-7.1, Grade E, for the requirements for acceptable air quality in the VES air storage tanks.
TS 3.7.6, ACTIONS Condition E, to provide a clearer description of the Condition of an inoperable VES because the stored air volume is below the specified minimum value, and SR 3.7.6.8 to identify the surveillance as a functional test of the main control room envelope pressure relief damper.
A list of attendees is provided as an Enclosure.
On September 7, 2023 (Agencywide Documents and Access Management System (ADAMS)
Accession No. ML23257A303), the meeting was noticed on the NRC public webpage.
The NRC staff opened the meeting with introductory remarks and a roll call of the attendees.
The SNC representative presented slides contained in ML23257A232.
SNC representatives discussed the following topics: (1) reason for the proposed change, (2) proposed LAR, (3) TS mark-up, (4) evaluation, (5) precedent, and (6) schedule.
SNC Proposed Changes SNC is proposing to change SR 3.7.6.5 to revise the referenced standard for the testing requirements for VES storage tanks air quality testing from American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. (ASHRAE) Standard 62-1989 to the American National Standards Institute (ANSI) / CGA Commodity Specification for Air, G-7.1, Grade E.
SNC is proposing to change ACTIONS Condition E of TS 3.7.6. Condition E applies when VES is inoperable because one bank of VES air tanks is inoperable; the associated Required Actions specify restoring VES to OPERABLE status within 7 days. SNC is proposing that while in this Condition, the stored amount of compressed air in the remaining OPERABLE VES air tanks must be verified to be greater than 245,680 standard cubic feet (scf) within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> and every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> thereafter. SNC is also proposing that ACTION E require verification of the availability of the Nuclear Island Nonradioactive Ventilation System (VBS) Main Control Room Envelope (MCRE) ancillary fans and supporting equipment within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. SNC proposes to modify TS 3.7.6, Condition E, to replace the Condition description of One bank of VES air tanks inoperable with Compressed air storage tanks contain 327,574 scf of compressed air.
SNC proposes to change Required Action E.1 to replace OPERABLE tanks with compressed air storage tanks.
SNC proposes to modify TS SR 3.7.6.8 to replace Verify each VES pressure relief damper is OPERABLE with Perform a functional test of each VES pressure relief damper.
Background
VES provides a protected environment from which operators can control the plant following an uncontrolled release of radioactivity, hazardous chemicals, or smoke. The system is designed to operate following a Design Basis Accident (DBA), which requires protection from the release of radioactivity. In these events, VBS would continue to function if alternating current (AC) power is available. If AC power is lost for greater than 10 minutes, or a Control Room Air Supply Radiation (particulate or iodine) High 2 (Limiting Condition of Operation (LCO) 3.3.13) signal is received, the VES is actuated.
The major functions of the VES are: (1) to provide forced ventilation to deliver an adequate supply of breathable air for the MCRE occupants; (2) to provide forced ventilation to maintain the MCRE at a 1/8-inch water gauge positive pressure with respect to the surrounding areas; (3) to provide passive filtration to filter contaminated air in the MCRE; and (4) to limit the temperature increase of the MCRE equipment and facilities that must remain functional during an accident, via the heat absorption of passive heat sinks.
The VES consists of compressed air storage tanks, two air delivery flow paths, an eductor, a high efficiency particulate air (HEPA) filter, an activated charcoal adsorber section for removal of gaseous activity (principally iodines), associated valves or dampers, piping, and instrumentation. The tanks contain enough breathable air to supply the required air flow to the MCRE for at least 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
The 32 air storage tanks (1 bank is 8 tanks with 4 banks) are constructed of forged, seamless pipe, with no welds, and conform to Section VIII and Appendix 22 of the American Society of Mechanical Engineers (ASME) Code. The design pressure of the air storage tanks is 4000 psi (pounds per square inch). The storage tanks collectively contain a minimum storage capacity of 327,574 scf.
The VES system is designed to maintain caron dioxide (CO2) concentration less than 0.5-percent by volume for up to 11 MCRE occupants.
The MCRE is the area within the confines of the MCRE boundary that contains the spaces that control room operators inhabit to control the unit during normal and accident conditions. This area encompasses the main control area, operations work area, operational break room, shift supervisors office, kitchen, and toilet facilities. The MCRE is protected during normal operation, natural events, and accident conditions. The MCRE boundary is the combination of walls, floor, roof, electrical and mechanical penetrations, and access doors. The OPERABILITY of the MCRE boundary must be maintained to ensure that the inleakage of unfiltered air into the MCRE will not exceed the inleakage assumed in the licensing basis analysis of DBA consequences to MCRE occupants. The MCRE and its boundary are defined in the Main Control Room Envelope Habitability Program.
The compressed air storage tanks are initially filled to contain greater than 327,574 scf of compressed air. The compressed air storage tanks, the tank pressure, and the room temperature are monitored to confirm that the required volume of breathable air is stored.
During operation of the VES, a self-contained pressure regulating valve maintains a constant downstream pressure regardless of the upstream pressure. An orifice downstream of the regulating valve is used to control the air flow rate into the MCRE. The MCRE is maintained at a 1/8-inch water gauge positive pressure to minimize the infiltration of airborne contaminants from the surrounding areas.
VES air header isolation valves are required to be verified open at 31-day intervals. SR 3.7.6.5 is designed to ensure that the pathways for supplying breathable air to the MCRE are available should loss of VBS occur. These valves should be closed only during required testing or maintenance of downstream components, or to preclude complete depressurization of the system should the VES isolation valves in the air delivery line open inadvertently or begin to leak.
For SR 3.7.6.8, verification that each VES pressure relief isolation valve within the MCRE pressure boundary is OPERABLE and is required in accordance with the Inservice Testing Program. SR 3.7.6.8. It is used in combination with SR 3.7.6.9 to ensure that adequate vent area is available to mitigate MCRE over pressurization.
For TS 3.7.6, Condition E, if one bank of VES air tanks (8 tanks out of 32 total) is inoperable, then the VES can supply air to the MCRE for 54 hours6.25e-4 days <br />0.015 hours <br />8.928571e-5 weeks <br />2.0547e-5 months <br /> (75 percent of the required 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />).
If the VES is actuated, the operator must take actions to maintain habitability of the MCRE once the air in the tanks has been exhausted. The VBS supplemental filtration mode or MCRE ancillary fans are both capable of maintaining the habitability of the MCRE after 54 hours6.25e-4 days <br />0.015 hours <br />8.928571e-5 weeks <br />2.0547e-5 months <br />.
With one bank of VES air tanks inoperable, action must be taken to restore OPERABLE status within 7 days. In TS 3.7.6, Condition E, the stored amount of compressed air in the remaining OPERABLE VES air tanks must be verified within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> and every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> thereafter to be
> 245,680 scf. The 245,680 scf value is 75 percent of the minimum amount of stored
compressed air that must be available in the compressed air storage tanks. The standard volume is determined using the compressed air storage tank room temperature (VAS-TE-080A/B), compressed air storage tanks pressure (VES-PT-001A/B), and Compressed Air Storage Tanks Minimum Volume - One Bank of VES Air Tanks (8 Tanks) Inoperable. Values above the 245,680 scf line in the figure meet the Required Action criteria.
Verification that the minimum volume of compressed air is contained in the OPERABLE compressed air storage tanks ensures a 54-hour air supply will be available if needed.
Additionally, within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, the VBS ancillary fans are verified to be OPERABLE so that, if needed, can be put into use once the OPERABLE compressed air storage tanks have been exhausted. The Completion Times associated with these actions and the 7-day Completion Time to restore VES to OPERABLE are based on engineering judgment, considering the low probability of an accident that would result in a significant radiation release from the reactor core, the low probability of radioactivity release, and that the remaining components and compensatory systems can provide the required capability. The 54 hours6.25e-4 days <br />0.015 hours <br />8.928571e-5 weeks <br />2.0547e-5 months <br /> of air in the remaining OPERABLE compressed air storage tanks, along with compensatory operator actions, are adequate to protect the main control room envelope habitability.
Discussion The SNC staff presented the slides regarding the proposed LAR with three proposed changes.
Regarding the first few slides on air quality, the NRC staff asked SNC if SNC is making any changes to the air supply path, same compressor, and does SNC have an alternate supply or a different standard. SNC staff replied that the high-pressure instrument air system is used to supply the storage tanks and self-contained breathing apparatus (SCBA) gear in the main control room (MCR), and this will not change. SNC staff stated that instrument air is Grade D, and SNC is not proposing to use instrument air.
The NRC staff asked about NUREG 0700, Human-System Interface Design Review Guidelines, Revision 3 (ML20162A214) published in July 2020. The NRC staff noted different criteria for breathable air, and asked SNC if SNC will address all criteria. SNC staff said that only appliable criteria are addressed, but SNC will check, and state which criteria are not appliable and why.
The NRC staff asked what version of the CGA G-7.1 standard was going to be used. SNC replied that it will use the 1989 version of the CGA G-7.1 standard. The NRC asked about a 2018 version, and SNC stated that SNC would investigate it.
The NRC staff asked about the precedent cited, and how it applies to the proposed LAR. The SNC staff replied that SNC is using the same standard review plan that was used for the NuScale application. The NRC staff asked SNC to cite how/why the precedent is applicable to the proposed LAR.
Regarding slide 15, the NRC staff asked why SNC wanted to remove the defined term OPERABLE from TS 3.7.6, Condition E and associated Required Actions. The NRC staff asked about the minimum volume of one bank, since as written Condition E appears to apply only if the total stored air volume is less than or equal to 75-pervcent of the specified minimum stored air volume of 327,524 scf. The SNC staff replied with the reference to the discussion in slide 16. The NRC staff asked if SNC had the pressure-temperature curves for the 32 tanks like in the AP1000 standard TS Bases. The SNC staff confirmed that Vogtle, Units 3 and 4, do have
pressure-temperature curves for the tanks. The SNC staff stated that Vogtle, Units 3 and 4, cannot continue power operation with two stored air banks (eight tanks per bank) out of service.
The NRC also questioned SNCs proposal to remove the defined term OPERABLE from TS 3.7.6, Condition E since proposed Condition E addresses when VES is inoperable, because the stored air volume in the 32 tanks is less than the specified minimum stored air volume of 327,524 scf. The NRC staff requested SNC to describe the situation corresponding to proposed Condition E. The NRC staff asked about when SNC would declare the VES inoperable and enter Condition E, and how Condition E is related to Required Action E.3, which requires restoring the stored air volume to the minimum value within 7 days.
The SNC staff said there are real world examples of Condition E. The SNC staff explained that the VES compressed air tank volume was discovered to be slightly below 327,524 scf ten months ago. SNC said that this was a situation of an inoperable VES, but Condition E did not clearly describe the situation. SNC stated that it had difficulty making the condition of one bank of tanks inoperable fit the situation, because all banks would have a reduced inventory, and the remaining air volume would not necessarily correspond to losing the air volume of one bank (25-percent of 327,524 scf). The NRC staff requested that SNC describe the logic it would use to decide whether to enter Condition E.
Regarding Slide 20, the NRC staff asked where the functional test required by proposed SR 3.7.6.8 (currently states: Verify the VES MCRE pressure relief damper is OPERABLE) is defined, and could the definition be included in TS 3.7.6. The SNC staff stated that there are no changes to any tests or procedures. The NRC staff commented about the challenge of using an undefined definition such as functional test versus the TS defined term OPERABLE, and not using this defined term as a criterion the Surveillance must meet raises a question in licensing space. The SNC staff stated it will evaluate the proposed use of functional test.
SNC stated that it planned to submit the proposed LAR in the fourth quarter of 2023, and SNC would request an approval from the NRC one year after an acceptance review.
The NRC staff said that SNC should think carefully about the no significant hazards consideration for the breathing air.
There were two members of the public in attendance. Nuclear Energy Oversight Project (NEOP) questioned why the licensee must make all these changes if NRC already approved the design.
During the meeting, NEOP questioned why the proposed changes were not anticipated during design. The NRC staff replied that the NRC issues licenses for all units and changes do occur based on operational experience and that NRC reviews all these changes appropriately. NEOP asked what the purpose is of the proposed LAR. The NRC staff explained that the proposed LAR is comprised of the 3 changes: (1) Air quality, (2) TS 3.7.6, Condition E, and (3) surveillance requirement. The NRC staff said that the NRC will review the proposed LAR and will either approve or deny it.
Subsequently, by letter dated October 8, 2023 (ML23283A049), NEOP submitted additional comments regarding the CGA and ASHRAE standards.
The NRC staff did not make any 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. Public Meeting Feedback forms were available, but no comments were received.
The meeting adjourned at 11:03 am Eastern Time (ET).
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.52-025 and 52-026
Enclosure:
List of Attendees cc w/encls: Distribution via Listserv
LIST OF ATTENDEES SEPTEMBER 28, 2023, PRE-SUBMITTAL MEETING WITH SOUTHERN NUCLEAR COMPANY REGARDING A PROPOSED TS 3.7.6 LICENSE AMENDMENT REQUEST VOGTLE ELECTRIC GENERATING PLANT, UNITS 3 AND 4 ATTENDEE REPRESENTING John G. Lamb U.S. Nuclear Regulatory Commission (NRC)
Mike Markley NRC Andrea Johnson NRC Joshua Wilson NRC Craig Harbuck NRC Derek Scully NRC Brian Wittick NRC Brian Green NRC Garry Armstrong NRC Lauren Nist NRC Cayetano Santos NRC Mark Blumberg NRC Sean Meighan NRC Keith Dorsey Southern Nuclear Operating Company (SNC)
Amy Chamberlain SNC Neil Haggerty SNC Eddie Grant SNC Dan Williamson SNC William Garrett SNC Christopher Parkes SNC Neil Haggerty SNC Thomas Saporito Nuclear Energy Oversight Project Mary Miller Dominion Enclosure
PKG ML23272A183 Meeting Notice ML23257A303 Meeting Summary ML23272A182 SNC Slides ML23257A232 NRC-001 OFFICE NRR/DORL/LPL2-1/PM NRR/DORL/LPL2-1/LA NRR/DSS/STSBB/BC NAME AJohnson KGoldstein MJardaneh (RElliott for)
DATE 09/28/2023 09/29/2023 10/10/2023 OFFICE NRR/DORL/LPL2-1/BC NRR/DORL/LPL2-1/PM NAME MMarkley (EMiller for) JLamb DATE 10/11/2023 10/11/2023