GNRO-2020/00033, Response to NRC Integrated Inspection Report 05000416/2020002
| ML20254A157 | |
| Person / Time | |
|---|---|
| Site: | Grand Gulf  |
| Issue date: | 09/10/2020 |
| From: | Emily Larson Entergy Operations |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| GNRO-2020/00033 IR 2020002 | |
| Download: ML20254A157 (8) | |
Text
GNRO-2020/00033 September 10, 2020 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001
Subject:
Response to NRC Integrated Inspection Report 05000416/2020002 Grand Gulf Nuclear Station, Unit 1 Docket No. 50-416 Renewed Facility Operating License No. NPF-29
Reference:
Letter dated August 6, 2020, from David L. Proulx (NRC) to Eric Larson (Entergy), Grand Gulf Nuclear Station - Integrated Inspection Report 05000416/2020002 (ML20219A414)
The purpose of this letter is to provide the Entergy Operations, Inc. (Entergy) response to the Grand Gulf Nuclear Station Non-Cited Violation (NCV) 2020002-03 contained in the referenced letter. This NCV stated that the licensee failed to report under 10 CFR 50.73(a)(2)(v), an event or condition that could have prevented fulfillment of a safety function. It is Entergys position that this violation should be withdrawn based on the response to the NCV in the enclosure to this letter. The enclosure to this letter contains a restatement of the NCV and provides Entergys response to the NCV.
This letter and enclosure were originally required to be sent by September 5, 2020. Based on approval by the Chief, Branch C, Region IV, on September 2, 2020; the required due date was extended to September 11, 2020.
This letter contains no new Regulatory Commitments. Should you have any questions concerning the content of this letter, please contact Jim Shaw, Manager Regulatory Assurance at 601-437-2103.
Respectfully, Eric A. Larson EAL/fas
Enclosure:
Response to NRC Integrated Inspection Report 05000416/2020002 Non-Cited Violation 2020002-03 cc: Senior Resident Inspector, Grand Gulf Nuclear Station Eric A. Larson Site Vice President Grand Gulf Nuclear Station Tel: 601-437-7500 Entergy Operations, Inc.
P.O. Box 756 Port Gibson, Mississippi 39150
Enclosure Response to NRC Integrated Inspection Report 05000416/2020002 Non-Cited Violation 2020002-03
Enclosure to GNRO-2020/00033 Page 1 of 6 Response to NRC Integrated Inspection Report 05000416/2020002 Non-Cited Violation 2020002-03
Background
The Grand Gulf Nuclear Station - Integrated Inspection Report 05000416/2020002 dated August 6, 2020 contained a Non-Cited Violation for failure to report a safety system functional failure for the Standby Gas Treatment System, NCV 05000416/2020002-03. This report stated, in part:
An NRC-identified Severity Level IV non-cited violation of 10 CFR 50.73 was identified when the licensee failed to report an event or condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to control the release of radioactive material. Specifically, Grand Gulf Nuclear Station Licensee Event Report 05000416/2019-006-00 (ADAMS Accession No. ML19322C805), documented a condition where the B train of the standby gas treatment system was inoperable for a period of approximately 19 days. The licensee event report reported this event in accordance with 10 CFR 50.73(a)(2)(i)(B), for a condition which was prohibited by the plants technical specification. However, the licensee event report did not identify this condition as a 10 CFR 50.73(a)(2)(v) condition when the A train of the standby gas treatment system was concurrently inoperable during a period of time that the B train was inoperable.
==
Description:==
Licensee Event Report (LER) 05000416/2019-006-00 documented a condition where the B train of standby gas treatment system (SGTS) was inoperable for approximately 19 days from September 4, 2019, until September 23, 2019. The LER was submitted to the NRC pursuant to 10 CFR 50.73(a)(2)(i)(B) for a condition which was prohibited by the plants technical specifications.
The LER stated that the A train of SGTS was operable and available during the event. However, while reviewing LER 05000416/2019-006-00, the inspectors identified that on September 19, 2019, the A train of SGTS was declared inoperable during surveillance testing per Procedure 06-OP-1T48-Q-0002, Standby Gas Treatment System A Valve Test, Revision 111. Surveillance Procedure 06-OP-1T48-Q-0002, Revision 111, required kill switches to be installed as well as the lifting of wires. As a result, operators declared the A train of SGTS inoperable, as it would no longer provide its function while in this condition absent additional operator action.
Following the guidance in NUREG-1022, Revision 3, Event Report Guidelines 10 CFR 50.72 and 50.73, the inspectors determined that the concurrent inoperability of the A and B trains of SGTS should have been reported to the NRC as a condition that could have prevented the fulfillment of a safety function, pursuant to 10 CFR 50.73(a)(2)(v). Specifically, both trains of SGTS were inoperable at the same time due to one or more equipment problems associated with degraded charcoal in the B SGTS.
Enclosure to GNRO-2020/00033 Page 2 of 6 On approximately May 29, 2020, the inspectors informed the licensee of the information they discovered regarding a potential condition that could have prevented the fulfillment of the SGTS safety function. The licensee entered the concern into its corrective action program on July 7, 2020.
Performance Assessment: The inspectors determined this violation was associated with a minor performance deficiency. Specifically, the failure to report a condition that could have prevented the fulfillment of a safety function is contrary to licensee Procedure EN-LI-108, Event Notification and Reporting, Revision 18.
Violation: Title 10 CFR 50.73(a)(1), requires, in part, that a licensee shall submit a LER for any event of the type described in this paragraph within 60 days after the discovery of the event. Specifically, 10 CFR 50.73(a)(2)(v) requires that the licensee shall report any event or condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to (1) shut down the reactor and maintain it in a safe shutdown condition; (2) remove residual heat; (3) control the release of radioactive material; or (4) mitigate the consequences of an accident.
Contrary to the above, on November 18, 2019, the licensee failed to submit a LER for an event of the type described in 10 CFR 50.73(a) within 60 days after the discovery of the event. Specifically, when the licensee declared the A train of SGTS inoperable for a surveillance test with the B train of SGTS concurrently inoperable due to a failed charcoal test, a condition existed that could have prevented the fulfillment of a safety function of a system that is needed, in part, to control the release of radioactive material.
Entergys Position Entergy denies that a violation of NRC requirements occurred, in that Entergy was in compliance with regulatory requirements. It is Entergys position that a condition did not exist that could have prevented the fulfillment of a safety function. The A train of SGTS was declared inoperable solely for the performance of a surveillance test in accordance with an approved procedure and the plants Technical Specifications (TSs) and no condition was discovered during the surveillance test that would have resulted in the system being declared inoperable. As a result, and in accordance with NUREG 1022, no report was required since the second criterion for reportability was not met; that is, the inoperability was not due to one or more personnel errors, including procedure violations; equipment failures; inadequate maintenance; or design, analysis, fabrication, equipment qualification, construction, or procedural deficiencies. The declaration of the A train as inoperable solely for the performance of an approved surveillance procedure did not eliminate its ability to perform its intended function, if required. The following information provides a more detailed discussion, as well as an example of current industry practice to support the conclusion that a safety system functional failure did not exist.
Enclosure to GNRO-2020/00033 Page 3 of 6 Specified Safety Function of SGTS The specified safety function of SGTS is to mitigate the consequences of an accident by filtering radioactive materials released from the primary containment into the secondary containment prior to release to the environment.
This function is accomplished by automatically starting upon radiation or LOCA signals, processing air in the Auxiliary Building through High Efficiency Particulate Air filters to remove particulate and Charcoal Adsorption filters for adsorption of gaseous fission products entrained within the Auxiliary Building air volume, and then exhausting the processed air to the environment.
Surveillance Procedure 06-OP-1T48-Q-0002, Revision 111, states that required installation of kill switches and lifting of wires during the performance of the surveillance may render the pressure control for SGTS inoperative when F006 is being tested. However, the declaration of inoperability for this test did not, render the safety function from being able to be performed.
Valve F006 is the SGTS train A suction control Volume Control Damper from the Steam Tunnel Outside Containment area. The Steam Tunnel Outside Containment area is located in the auxiliary building (Reference UFSAR page 6.5-48) and backs up to the turbine building.
UFSAR Section 6.5.3.4 discusses the failure of individual control dampers and for failed open dampers concludes, (t)he effect of a stuck open volume control damper on air flows within the enclosure building will be negligible. Alternately if F006 were to fail closed, the Steam Tunnel Outside Containment area may not achieve the design negative pressure for the operation of the SGTS train A. As discussed in UFSAR section 6.2.3.3, any exfiltration from the area due to failure to achieve the desired negative differential pressure would be low since the auxiliary building walls are concrete. Also, as discussed in UFSAR Section 6.2.3.3, exfiltration rates of up to 100 scfm have been evaluated and found to be acceptable. The infiltration analysis discussed in UFSAR Section 6.2.3.3 demonstrates that this area would not be expected to infiltrate or exfiltrate more than 100 scfm at 1/4 differential pressure. As a result SGTS train A could have performed its safety function during the subject valve test.
Therefore, although the operator declared the train inoperable as allowed by Surveillance Procedure 06-OP-1T48-Q-0002, the A train of SGTS continued to be able to perform its safety function, if required to do so.
If the A train of SGTS had not successfully passed the surveillance test, the A train would have been maintained as inoperable. When the B train was also found to have been inoperable based on the results of the charcoal testing, a Safety System Function Failure would have been reportable under the cited regulation.
Licensing Basis Review The GGNS Operating License, TS and associated Bases were reviewed. No new information was obtained from this review that indicates that the system could not perform its specified safety function. The TSs require performance of the surveillances to demonstrate continued operability of the system.
Enclosure to GNRO-2020/00033 Page 4 of 6 The GGNS UFSAR 6.5.3 was reviewed. This section includes the failure modes analysis (FMA) of the SGTS. Included in the FMA is a discussion on the failure of volume control dampers (i.e.,
1T48F006 damper subject to the kill switch) either in the open or closed position.
The UFSAR Section 6.5.3.4 provides that a failure of a volume control damper in either position minimally impacts the ability of the SGTS to maintain the negative pressure configuration of the Auxiliary Building, and a failure does not impact the filtration capability of the system. As a result, the impact of the kill switch installation removing the damper positioning logic for 11 minutes would have no more than a minimal impact on the safety function. During this 11-minute duration, Train B remained fully operable for the initiation, draw down and filtration aspects of the system. The charcoal adsorption portion of Train B was the only sub-train portion of the system that was later determined to not meet its Technical Specification efficiency requirement of 99.5%. It should be noted that sample results indicated that the SGTS B train maintained an efficiency of 98.9%.
Regulatory Basis 10 CFR 73(a)(2)(v)
Any event or condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to:
(A) Shut down the reactor and maintain it in a safe shutdown condition; (B) Remove residual heat; (C) Control the release of radioactive material; or (D) Mitigate the consequences of an accident.
Events covered in paragraph (a)(2)(v) of this section may include one or more procedural personnel errors, equipment failures, and/or discovery of design, analysis, fabrication, construction, and/or procedural inadequacies. However, individual component failures need not be reported pursuant to paragraph (a)(2)(v) of this section if redundant equipment in the same system was operable and available to perform the required safety function.
NUREG 1022 (page 39)
A SSC that has been declared inoperable is one in which the SSC capability is degraded to a point where it cannot perform with reasonable expectation or reliability.
As a result, for SSCs within the scope of this criterion, a report is required when
- 1) there is a determination that the SSC is inoperable in a required mode or other specified condition in the TS Applicability,
- 2) the inoperability is due to one or more personnel errors, including procedure violations; equipment failures; inadequate maintenance; or design, analysis, fabrication, equipment qualification, construction, or procedural deficiencies, and
- 3) no redundant equipment in the same system was operable.
As a result, reports are not required when systems are declared inoperable as part of a planned evolution for maintenance or surveillance testing when done in accordance with an approved procedure and the plants TS (unless a condition is discovered that would have resulted in the system being declared inoperable).
Enclosure to GNRO-2020/00033 Page 5 of 6 Based on the above guidance from NUREG 1022 from the previous paragraph (emphasis added) no report would have been required.
Entergy acknowledges that there is an example discussed in NUREG 1022 (page 40, example
- 4) which involves the loss of two trains in a two-train system and the requirement to submit an LER. However, this example is not an applicable example to the situation that occurred with the SGTS. While analogous to one train being out of service for maintenance, the B train was inoperable based on the filter test; unlike the example from NUREG 1022, the A SGTS train passed its surveillance. The example provided in the NUREG shows the inability of the system to perform the specified safety function. Since train A of SGTS continued to be able to perform the safety function both prior to and after performance of the Volume Control Damper surveillance for the system, NUREG 1022 (page 40, example 4) is not a representative example of what occurred.
SGTS train A was declared inoperable only because a planned, scheduled, and required quarterly surveillance test, using an approved procedure, was performed. This procedure directed the declaration of inoperability and included appropriate procedural steps for immediate restoration of SGTS train A in the event of a condition requiring system initiation and actuation. The surveillance was performed to demonstrate operability of the system as required by TS. The SGTS train A was operable before the 11-minute test and operable after the 11-minute test, with no abnormalities noted during the test. Previous successful tests and subsequent successful tests support that SGTS train A did not show any indication of degradation.
Therefore, though the system was declared inoperable for 11 minutes, the system was able to perform as designed, was not in a failed or degraded condition and could have performed its specified safety function before, after and during that time, if required to do so.
Reporting In accordance with NUREG-1022, for a condition to be reported as a SSFF, the SSC must meet all three of the following criteria:
- 1) there is a determination that the SSC is inoperable in a required mode or other specified condition in the TS Applicability Operations declared SGTS train A inoperable on September 19, 2019 from 2345 to 2356 (11 minutes) only to perform a required surveillance. The plant was in Mode 1. SGTS is required to operable in Mode 1.
- 2) the inoperability is due to one or more personnel errors, including procedure violations; equipment failures; inadequate maintenance; or design, analysis, fabrication, equipment qualification, construction, or procedural deficiencies, and SGTS train A was declared inoperable solely due to a planned and scheduled required surveillance using an approved procedure which directed the inoperability, and with appropriate provisions within the surveillance procedure for immediate restoration of SGTS train A in the event a condition requiring operation
Enclosure to GNRO-2020/00033 Page 6 of 6 of SGTS train A should occur. The system inoperable condition did not meet this criterion.
- 3) no redundant equipment in the same system was operable.
At the time of the SGTS train A surveillance, SGTS train B was considered operable. It was later discovered that the SGTS train B filter media was deficient during the time that the SGTS train A surveillance was performed. SGTS train B is the redundant subsystem for SGTS train A.
Based on the SSC condition only meeting 2 of 3 criteria for reportability, the condition is not reportable as a SSFF.
As an example, a system condition that is most closely aligned with this GGNS SGTS issue is performance of a diesel generator surveillance where a station has two diesel generator emergency power supplies. One of the two diesels is out of service for maintenance and is not immediately recoverable. The second diesel generators surveillance is due to be performed.
When the second diesel generator surveillance is initiated, the surveillance would require the second diesel generator to be declared inoperable to perform the surveillance. During the surveillance performance the diesel generator selector switch, in accordance with the approved procedure, must be placed in manual. Placing the diesel generator selector switch to manual causes the diesel generator to become inoperable for the purpose of receiving an auto initiation signal, due to the receipt of a valid actuation signal. The diesel generator is considered inoperable during the period that the selector switch is in the manual position. Allowance is given for performing the surveillance under an approved and valid procedure to conduct the surveillance. If the outcome results in the diesel generator successfully completing the surveillance, the diesel generator obviously remains operable. In the event the diesel generator fails its surveillance, a safety system functional failure would exist, and a reportable condition would also exist based on NUREG 1022 page 39 requirements.
Based on the SGTS issue being compared to this example, there was no safety system functional failure when the SGTS surveillance was successfully performed under an approved and valid procedure, and not meeting the criteria for a safety system functional failure as defined by NUREG 1022.
Conclusion A condition did not exist that could have prevented the fulfillment of a safety function and Entergy was in compliance with regulatory requirements. The A train of SGTS would have been capable of performing its required function during the performance of the surveillance test.
The A train of SGTS was declared inoperable solely for the performance of a surveillance test in accordance with an approved procedure and the plants TSs and no condition was discovered during the surveillance test that would have resulted in the system being declared inoperable.
As a result, and in accordance with NUREG 1022, no report was required. It is Entergys position that the Severity Level IV Non-Cited Violation 05000416/2020002-03 should be withdrawn based on this response.