IR 05000458/2021013

Rriver Bend Station - NRC Baseline Inspection Report 05000458/2021013

ML21145A186
Person / Time
Site:	River Bend
Issue date:	05/25/2021
From:	Jason Kozal NRC/RGN-IV/DRP/RPB-C
To:	Vercelli S Entergy Operations
References
EA-21-036 IR 2021013
Download: ML21145A186 (14)

Text

May 25, 2021

SUBJECT:

RIVER BEND STATION - NRC BASELINE INSPECTION REPORT 05000458/2021013

Dear Mr. Vercelli:

On April 29, 2021, the U.S. Nuclear Regulatory Commission (NRC) completed an inspection at River Bend Station and discussed the results of this inspection with you and other members of your staff. The results of this inspection are documented in the enclosed report.

One Severity Level IV violation without an associated finding is documented in this report. We are treating this violation as a non-cited violation (NCV) consistent with Section 2.3.2 of the Enforcement Policy.

If you contest the violation or the severity of the violation documented in this inspection report, you should provide a response within 30 days of the date of this inspection report, with the basis for your denial, to the U.S. Nuclear Regulatory Commission, ATTN: Document Control Desk, Washington, DC 205550001; with copies to the Regional Administrator, Region IV; the Director, Office of Enforcement; and the NRC Resident Inspector at River Bend Station. This letter, its enclosure, and your response (if any) will be made available for public inspection and copying at http://www.nrc.gov/reading-rm/adams.html and at the NRC Public Document Room in accordance with Title 10 of the Code of Federal Regulations 2.390, Public Inspections, Exemptions, Requests for Withholding.

Sincerely, Jason W. Digitally signed by Jason W. Kozal Kozal Date: 2021.05.25 15:17:43 -05'00'

Jason W. Kozal, Chief Reactor Projects Branch C Division of Reactor Projects Docket No. 05000458 License No. NPF-47

Enclosure:

As stated

Inspection Report

Docket Number: 05000458 License Number: NPF-47 Report Number: 05000458/2021013 Enterprise Identifier: I-2021-013-0005 Licensee: Entergy Operations, Inc.

Facility: River Bend Station Location: St. Francisville, LA Inspection Dates: February 15, 2021 to May 31, 2021 Inspectors: R. Kumana, Senior Resident Inspector C. Wynar, Resident Inspector Approved By: Jason W. Kozal, Chief Reactor Projects Branch C Division of Reactor Projects Enclosure

SUMMARY

The U.S. Nuclear Regulatory Commission (NRC) continued monitoring the licensees performance by conducting an Event Follow-up inspection at River Bend Station, in accordance with the Reactor Oversight Process. The Reactor Oversight Process is the NRCs program for overseeing the safe operation of commercial nuclear power reactors. Refer to https://www.nrc.gov/reactors/operating/oversight.html for more information.

List of Findings and Violations

Failure to Provide Complete and Accurate Information in Response to a 10 CFR 50.54.f Information Request Cornerstone Severity Cross-Cutting Report Aspect Section Not Applicable Severity Level IV Not Applicable 71153 NCV 05000458/2021013-01 Open/Closed EA-21-036 The inspectors identified a Severity Level IV, non-cited violation of 10 CFR 50.9,

Completeness and Accuracy of Information, associated with the licensees failure to ensure information provided to the Commission was complete and accurate in all material respects.

Specifically, the information provided in the final report submitted on March 12, 2014, in response to the agencys request for information issued on March 12, 2012, to support Recommendation 2.3 of the Near-Term Task Force review of insights from the Fukushima Dai-ichi accident, pursuant to 10 CFR 50.54.f, was incomplete and inaccurate with respect to details regarding the configuration of the Unit 2 excavation pit and flood control berm and the associated function to prevent flooding in the safety-related G tunnel.

Additional Tracking Items

Type Issue Number Title Report Section Status LER 05000458/2020-003-00 Weep Holes Discovered in 71153 Closed G-Tunnel Wall Result in Inoperable Safety-Related Equipment

INSPECTION SCOPES

Inspections were conducted using the appropriate portions of the inspection procedures (IPs) in effect at the beginning of the inspection unless otherwise noted. Currently approved IPs with their attached revision histories are located on the public website at http://www.nrc.gov/reading-rm/doc-collections/insp-manual/inspection-procedure/index.html. Samples were declared complete when the IP requirements most appropriate to the inspection activity were met consistent with Inspection Manual Chapter (IMC) 2515, Light-Water Reactor Inspection Program - Operations Phase. The inspectors reviewed selected procedures and records, observed activities, and interviewed personnel to assess licensee performance and compliance with Commission rules and regulations, license conditions, site procedures, and standards.

Starting on March 20, 2020, in response to the National Emergency declared by the President of the United States on the public health risks of the Coronavirus Disease 2019 (COVID-19),resident inspectors were directed to begin telework and to remotely access licensee information using available technology. During this time, the resident inspectors performed periodic site visits each week; conducted plant status activities as described in IMC 2515, Appendix D, Plant Status; observed risk-significant activities; and completed on-site portions of IPs. In addition, resident and regional baseline inspections were evaluated to determine if all or portions of the objectives and requirements stated in the IP could be performed remotely. If the inspections could be performed remotely, they were conducted per the applicable IP. In some cases, portions of an IP were completed remotely and on-site. The inspections documented below met the objectives and requirements for completion of the IP.

OTHER ACTIVITIES - BASELINE

71153 - Followup of Events and Notices of Enforcement Discretion Event Report (IP Section 03.02)

The inspectors evaluated the following licensee event report (LER):

(1) LER 05000458/2020-003-00, Weep Holes Discovered in G-Tunnel Wall Result in Inoperable Safety-Related Equipment (ADAMS Accession No. ML20300A577). The circumstances surrounding this LER and an associated non-cited violation are documented in the Inspection Results section of this report.

INSPECTION RESULTS

Failure to Provide Complete and Accurate Information in Response to a 10 CFR 50.54.f Information Request Cornerstone Severity Cross-Cutting Report Aspect Section Not Severity Level IV Not 71153 Applicable NCV 05000458/2021013-01 Applicable Open/Closed EA-21-036 The inspectors identified a Severity Level IV, non-cited violation of 10 CFR 50.9, Completeness and Accuracy of Information, associated with the licensees failure to ensure information provided to the Commission was complete and accurate in all material respects.

Specifically, the information provided in the final report submitted on March 12, 2014, in response to the agencys request for information issued on March 12, 2012, to support Recommendation 2.3 of the Near-Term Task Force review of insights from the Fukushima Dai-ichi accident, pursuant to 10 CFR 50.54.f, was incomplete and inaccurate with respect to details regarding the configuration of the Unit 2 excavation pit and flood control berm and the associated function to prevent flooding in the safety-related G tunnel.

Description:

During a review of external flood protection, the inspectors identified that the facility had a vulnerability to flooding in the G tunnel, a safety-related structure. The tunnel was originally intended to connect Unit 1 to a planned second unit. The licensee cancelled the second unit after excavating the site and left the excavation pit unfilled after licensing.

The licensee installed a ventilation system through the tunnel wall with a vertical ventilation shaft. In the design basis flood analysis, the licensee identified that flooding from intense precipitation could result in the pit filling up and potentially affecting the adjacent safety-related structures, systems, and components (SSCs) of Unit 1, including the Unit 1 ultimate heat sink (UHS). The licensee had determined that flood water could intrude into the G tunnel at an elevation of 80.5 feet through the top of the ventilation shaft. In order to maintain water level in the pit below that level, the licensee constructed a flood control berm around the north side of the pit to direct runoff away from the pit and into existing channels. Based on the construction of the berm, the licensee determined that the maximum level of water that could accumulate in the pit was 80.3 feet mean sea level (MSL). The level at which water in the pit could affect Unit 1 was 80.5 feet MSL. The inspectors identified multiple design control violations associated with failures to incorporate changes to the site into the flood protection design basis, failure to use accurate assumptions in calculations, and failure to control critical parameters including the initial assumed water level in the pit. These violations were documented in NRC Inspection Report 05000458/2020004 (ADAMS Accession No. ML21041A546).

Based on questions that arose from these issues, the inspectors reviewed the licensees Flood Hazard Re-evaluation Report (referred to from hereon as the FHRR) submitted to the NRC in March 2014. On March 12, 2012, the NRC issued an information request under 10 CFR 50.54(f) as part of the agencys Near-Term Task Force (NTTF) review of the accident at the Fukushima Dai-ichi nuclear facility. The required response included a report described in the letter under the section titled, Recommendation 2.1: Flooding, in the paragraph titled Requested Information under Item 1, Hazard Reevaluation Report. The agency detailed the information required to be included in this report. Specifically, licensees were requested to provide:

Site information related to the flood hazard. Relevant SSCs important to safety and the UHS are included in the scope of this reevaluation, and pertinent data concerning these SSCs should be included. Other relevant site data includes the following:

i.

detailed site information (both designed and as-built), including present-day site layout, elevation of pertinent SSCs important to safety, site topography, as well as pertinent spatial and temporal data sets ii.

current design basis flood elevations for all flood causing mechanisms iii.

flood-related changes to the licensing basis and any flood protection changes (including mitigation) since license issuance iv.

changes to the watershed and local area since license issuance v.

current licensing basis flood protection and pertinent flood mitigation features at the site vi.

additional site details, as necessary, to assess the flood hazard (i.e., bathymetry, walkdown results, etc.)

The licensee responded to this request on March 12, 2014, with the FHRR referenced above.

The agency had requested that licensees perform a re-evaluation of the flood hazards using modern evaluation methods. The licensee re-evaluated the precipitation flood mechanism using the Local Intense Precipitation (LIP) methodology and compared the resulting flood level to the existing design basis flood level. In addition, the licensee re-evaluated the probable maximum flood (PMF) for the West Creek, which ran adjacent to the west side of the excavation pit. In the FHRR, the licensee stated that the revised LIP evaluation was not bounded for certain areas on site, but specifically stated that the LIP evaluation flood level was bounded by the design basis flood level for the Unit 2 excavation area. The licensees re-evaluation of the PMF for the West Creek was also reported as bounded for the Unit 2 excavation.

The NRC staff responsible for reviewing the information in the FHRR submitted a request for additional information (RAI) by email on April 27, 2015. The licensee responded to the RAI on May 27, 2015. Based on the information provided in the FHRR and RAI, the agency provided an interim response which concluded that the flood hazard information in the FHRR was suitable for further assessments in a letter dated September 4, 2015 (ADAMS Accession No.

ML15212A727). The agency then documented the basis for these conclusions in a staff assessment letter dated August 31, 2016 (ADAMS Accession No. ML16204A207). In that letter, the agency stated that the licensee was expected to submit a focused evaluation to address the local intense precipitation reevaluated flood hazard [for the Unit 1 areas identified as exceeding the design basis flood levels] and either:

(1) an integrated assessment; or

(2) a focused evaluation to address the rivers and streams flood-causing Mechanisms. The agency concluded that, based on the information provided by the licensee in the FHRR, those revised flood mechanisms were not bounded by the design basis flood mechanisms. The LIP reevaluated hazard for the Unit 2 excavation (i.e., the G tunnel) was determined to be below the design basis level and did not require further evaluation.

The licensee then submitted a focused evaluation on June 28, 2017, to address the remaining information requested by the agency. This evaluation addressed the areas previously identified by the licensee where the revised flood mechanisms were not bounded.

In a letter dated August 23, 2017 (ADAMS Accession No. ML17220A113), the agency concluded that the licensees response was complete and met the requirements of the information request.

After reviewing the FHRR in light of the information uncovered during the recent external flooding inspection sample, the inspectors identified information in the FHRR that appeared to be inaccurate or incomplete.

The inspectors noted that the FHRR did not describe detailed information regarding the G tunnel and its ventilation shaft. Specifically, the licensee did not identify the safety-related SSCs in the G tunnel that were below the design basis flood level. The inspectors noted that specific safety-related SSCs in the G tunnel include motor operated valves required to reposition upon actuation of the standby service water system. The inspectors also noted that other safety-related SSCs exist in adjacent tunnels that are not sealed off from the G tunnel. These include level instruments for automatic operation of the high-pressure core spray and reactor core isolation cooling systems. These SSCs are vulnerable to flooding from water accumulation in the Unit 2 excavation pit from three pathways:

1. Door TU-66-01 in the G tunnel, a flood barrier that opens to the pit at an elevation of

66 feet MSL.

2. Hatch TU-67-H1 in the G tunnel, a flood barrier that opens to the pit at an elevation of 67 feet MSL.

3. The G tunnel ventilation shaft opening at 80.5 feet MSL. This opening is covered by a filter assembly, but the filter assembly itself is not rated for flood protection.

The inspectors also identified that two weep holes existed in the ventilation shaft that opened to the excavation pit at 66 feet MSL. These weep holes were not accounted for in the original design basis but could have been identified through a more thorough review of information required to be provided in response to the information request or during the licensee walkdowns conducted in response to the 50.54(f) letter. The failure to account for or remove the weep holes was documented as a violation in Inspection Report 05000458/2020004 (ADAMS Accession No. ML21041A546).

The licensee did not describe individual SSCs pertinent to flooding in the FHRR. Instead, the licensee included the following statements:

Section 2.2: The CLB [current licensing basis] for flooding protection at RBS [River Bend Station] is described in the USAR [updated safety analysis report]

Section 2.3.2: Internal and external flood protection is provided for the safety-related systems and components identified in USAR Table 3.2-1 for all postulated flood levels and conditions Section 2.3.2: The access openings to the structures housing safety-related components are either located above the DBFL [design basis flood level] or are required to be closed to prevent any adverse effect from flooding of the structures.

Section 2.4: The plant design features and their functional requirements that provide protection against the design basis external flood mechanisms are provided in the USAR (RBS 2013, Section 3.4). Attributes of the overall plant configuration that support the design for external flooding are also identified.

Section 3.3: There are no on-site dams or levees which could impact site safety if breached.

These statements, while not specifically inaccurate, did not provide the information pertinent to the request. Instead, the statements either directly referenced the USAR, or provided general descriptions that did not address specific SSCs.

Referencing the USAR could have been acceptable if the required information was in the referenced portions. However, the inspectors identified that the USAR did not include the most recent information pertaining to the current licensing basis flood hazard level in the Unit 2 excavation pit. The inspectors documented a separate violation for failure to include the information in the USAR required by 10 CFR 50.71(e) in NRC Inspection Report 05000458/2020004. In addition, specific details that were material to the information request were not contained in the USAR because the level of detail in the referenced sections was not consistent with the level of detail of the request. Specifically, the licensee failed to include in the FHRR the following pertinent information that was required to be provided:

1. The G tunnel was a safety-related structure that required protection from external flooding mechanisms.

2. Safety-related SSCs in the G tunnel were vulnerable to and required to be operable during a design basis external flood hazard.

3. The three penetrations in the G tunnel were protected by flood control structures, including the door, the hatch, and the flood control berm.

4. A potential failure of the berm could impact site safety by allowing flood water to rise above the 80.5ft MSL opening in the ventilation shaft and enter the G tunnel.

The inspectors reviewed the documented responses from the agency and discussed the incomplete information with cognizant NRC staff who would have reviewed the information, and determined that if the licensee had included the above information in the FHRR, the staff would have requested additional information regarding the use of the berm for flood protection of SSCs in the G tunnel prior to acceptance of the RBS FHRR. Specifically, the staff would have requested information regarding the type of the berm, the design criteria used for the berm, hydraulic properties of the construction materials, and method of construction of the berm.

In addition, the licensee used an incorrect assumption in their re-evaluation of the flood mechanisms as required by the agencys information request. The agency had requested a re-evaluation of the flood hazards using modern evaluation methods. Based on their evaluation, the licensee re-evaluated the precipitation flood mechanism using the Local Intense Precipitation (LIP) methodology and compared the resulting flood level to the existing design basis flood level. In addition, the licensee re-evaluated the probable maximum flood (PMF) for the West Creek, which ran adjacent to the west side of the excavation pit. In the FHRR, the licensee stated that the revised LIP evaluation was not bounded for certain areas on site, but specifically stated that the LIP evaluation flood level was bounded by the design basis flood level for the Unit 2 excavation area. The licensees re-evaluation of the PMF for the West Creek was similarly bounded. The inspectors reviewed the assumptions that were used to reach those conclusions. On page 3-3 of the FHRR, the report states:

Unit 2 Excavation: The Unit 2 excavation was assumed dry at the start of simulation as the excavation is maintained dry based on RBS Procedure OSP - 0031 (RBS 2014).

The inspectors determined that the statement that the excavation is maintained dry based on Procedure OSP-0031 is inaccurate. The inspectors reviewed the Procedure OSP-0031 and found that it contains no requirement to monitor the excavation or ensure it is dry. The inspectors determined that the licensee has no processes or procedures for ensuring or maintaining the excavation in a dry state. Furthermore, the inspectors inspected the pit and found that the excavation pit typically has standing water in the southwest corner. The inspectors noted that the original design basis assumes a starting water level of 65 feet MSL prior to the initiation of the design basis PMP event. Further discussion with the licensee showed that the licensee periodically partially dewaters the pit but does not pump the pit dry or control the amount of water remaining in the pit. As a result, the licensee incorrectly assumed the excavation was dry and provided an inaccurate basis for their assumption in the report. The inspectors determined that, in the RAI submitted by NRC staff on April 27, 2015, under a paragraph designated as RAI Item 10, General: Unit 2 Excavation during PMF, the staff made the following request:

Request: Justify modeling the Unit 2 Excavation with no initial standing water conditions. Provide documentation that supports the Unit 2 Excavation being credited as a flood protection feature in the design basis. Provide information on whether the feature is considered permanent or whether its relevant characteristics and/or function could change in the future.

In their response to Item 10 of the RAI, the licensee made the following statements:

RBS Procedure OSP-0031 requires that equipment located at the base of the Unit 2 Excavation be inspected daily (RBS 2013, Items 29 and 30). If there are accessibility issues due to flooding, pumps will be used to dewater the excavation as needed.

A 40 percent antecedent PMP event prior to the PMP induced PMF on West Creek would potentially result in standing water in the Unit 2 Excavation. The amount of water ponding in the Excavation is expected to be relatively low, due to the surrounding elevated berm, and the lack of overtopping from West Creek.

Additionally, the 72-hour dry period between the antecedent rain event and the PMF, as well as the lag between the onset of the PMF and actual overtopping of West Creek into the Unit 2 Excavation, is considered sufficient to dewater to allow for daily equipment inspection per RBS procedures.

The inspectors noted that the Procedure OSP-0031, Revision 63, referenced in the RAI response contained two requirements to inspect equipment located in the Unit 2 excavation, including a sewer tank and piping associated with a temporary modification in place at the time that was located in the Unit 2 excavation. However, the inspectors concluded that the response was still inaccurate. First, the inspectors noted that the temporary piping was located only in the southeast corner of the Unit 2 excavation and the sewer tank was located in the east side of the excavation, while the lowest portion of the excavation was in the southwest corner, where the standing water was located. Furthermore, the inspectors noted that even if pumps were used to dewater the excavation as needed, this would not necessarily result in a complete dewatering of the excavation, and no justification was provided for the water that might remain for either the LIP or the revised PMF scenario.

The inspectors discussed the inaccurate information with cognizant NRC staff who would have reviewed the information and determined that if the licensee had disclosed that the pit was not maintained dry, the staff would have requested additional information regarding the standing water in the pit and the justification for excluding it from the LIP analysis that was performed, prior to acceptance of the RBS FHRR. The inspectors noted that this information was requested in the RAI, but the licensee provided similar inaccurate information. If the licensee had provided the correct information, the NRC would have requested information on the depth of the standing water, information on the duration of ponding, and analysis of the impact of the ponding water on the local intense precipitation and onsite flooding analysis. A finding associated with the licensees failure to implement measures to control the initial water level in the pit was issued separately in NRC Inspection Report 05000458/2020004.

Based on the issues detailed above, the agency was not provided with the information required to fully assess the impact of the potential maximum LIP or PMF flood elevation in the Unit 2 excavation pit. Specifically, the potential for existing standing water in the excavation pit or failure of the berm under a LIP or PMF condition could potentially result in a water level in the excavation pit that exceeds the USAR documented design basis protection level of 80.5 feet. The licensees failure to describe the function of the excavation pit with respect to protection of safety-related SSCs located in the G tunnel can be directly tied to the NRC staffs conclusion that the Unit 2 excavation did not affect flood protection for Unit 1.

Additionally, in Section 3.3 of the assessment, NRC staff stated that nor are there onsite dams, levees, water control, or water storage structures that could fail at the RBS site. The licensees failure to describe the Unit 2 excavation berm as a structure that was credited with mitigating the external flood hazard for Unit 1 can be directly tied to the NRC staffs incorrect assumption that it was not a credited water control structure in the external flooding design basis.

Based on the results of the inspections and review of all the documents submitted by the licensee, the inspectors have determined that the agency was not provided with complete and accurate information regarding the potential impact of the revised LIP flood mechanisms on the G tunnel. The inspectors also determined that sufficient information was not available to the NRC to determine whether the G tunnel should have been included in the areas that required further evaluation. Had the licensee provided complete and accurate information as described above, the NRC would have made further inquiries by requesting information about the adequacy of the Unit 2 excavation pit and berm with respect to protection of Unit 1 against external flooding, and the validity of the basis for the licensees assumption that the Unit 2 excavation pit would be maintained dry at all times. The inspectors determined, after consulting with cognizant agency staff, that the additional inquiries would not have been considered substantial, nor would they have resulted in the agency considering a different regulatory position.

This Severity Level IV, non-cited violation closes Licensee Event Report 05000458/2020-003-00 dated October 26, 2020.

Corrective Actions: The licensee entered this issue into their corrective action program.

Corrective Action References: Condition Report CR-RBS-2021-02274

Performance Assessment:

This violation was associated with a previously documented finding assessed using the significance determination process which was documented as NCV 05000458/2020004-01 in NRC Integrated Inspection Report 05000458/2020004.

Enforcement:

The ROPs significance determination process does not specifically consider the regulatory process impact in its assessment of licensee performance. Therefore, it is necessary to address this violation which impedes the NRCs ability to regulate using traditional enforcement to adequately deter noncompliance.

Severity: Because the violation had the potential to impact the NRCs ability to perform its regulatory function, it is necessary to address this violation using traditional enforcement to adequately deter noncompliance. Using the NRC Enforcement Policy, dated January 15, 2020, the violation was determined to be a Severity Level IV violation in accordance with Section 6.9. While inaccurate or incomplete information was provided, if the information had been completely and accurately provided or maintained, it would not likely have caused the NRC to reconsider a regulatory position or undertake a substantial further inquiry.

Violation: Title 10 CFR 50.9(a), requires, in part, that information provided to the Commission by a licensee shall be complete and accurate in all material respects.

Contrary to the above, on March 12, 2014, the licensee provided information to the Commission that was not complete and accurate in all material respects. Specifically, the licensees response to a 10 CFR 50.54.f information request issued by the NRC on March 12, 2012, contained incomplete and inaccurate information that the NRC relied on with respect to re-evaluation of the licensees flood hazards.

Enforcement Action: This violation is being treated as a non-cited violation (NCV), consistent with Section 2.3.2 of the Enforcement Policy.

EXIT MEETINGS AND DEBRIEFS

The inspectors verified no proprietary information was retained or documented in this report.

• On April 29, 2021, the inspectors presented the inspection results to Mr. S. Vercelli, Site Vice President, and other members of the licensee staff.

DOCUMENTS REVIEWED

Inspection Type Designation Description or Title Revision or

Procedure Date

71153 Corrective Action CR-RBS- 2021-02119, 2020-03876, 2020-03880

Documents

71151 Drawings EB-036C Ventilation, Remote Air and Chilled Water Piping Tunnels 12

71151 Miscellaneous 51-9207360-000 Entergy Fleet Fukushima Program Flood Hazard 0

Reevaluation Report for River Bend Station

71151 Miscellaneous EC41004 Provide Temporary Discharge Path for Groundwater from

Well MW-125 in Unit 2 Hole to Blowdown Pit

71151 Miscellaneous RBG-47573 Response to Request for Additional Information on River 05/27/2015

Bend Station Recommendation 2.1 Flood Hazard Re-

evaluation

71151 Procedures OSP-0031 Log Report - Outside Area 63

11