IR 05000348/2022090
| ML23044A393 | |
| Person / Time | |
|---|---|
| Site: | Farley  |
| Issue date: | 02/16/2023 |
| From: | Diane Jackson NRC/RGN-II/DRP/RPB2 |
| To: | Gayheart C Southern Nuclear Operating Co |
| References | |
| EA-22-095 IR 2022090 | |
| Download: ML23044A393 (10) | |
Text
February 16, 2023
SUBJECT:
JOSEPH M. FARLEY NUCLEAR PLANT-NRC INSPECTION REPORT 05000348/2022090
Dear Cheryl Gayheart:
On September 30, 2022, the U.S. Nuclear Regulatory Commission (NRC) issued Inspection Report 05000348/2022050 (ADAMS Accession No. ML22272A557). The report documented one apparent violation (AV) for which the NRC had not yet reached a preliminary significance determination. Based on subsequent review, the NRC has completed the final disposition regarding this apparent violation. On February 2, 2023, the NRC discussed the results of the evaluation with Delson Erb, Site Vice President and other members of your staff. The results are documented in the enclosed report.
One finding of very low safety significance (Green) is documented in this report. This finding involved a violation of NRC requirements. 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 significance or 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 20555-0001; with copies to the Regional Administrator, Region II; the Director, Office of Enforcement; and the NRC Resident Inspector at Joseph M. Farley Nuclear Plant.
For administrative purposes, this letter is issued as NRC Inspection Report 05000348/2022090.
Accordingly, the AV documented in NRC Inspection Report 05000348/2022050 (ML22272A557)
is now designated as NCV 05000348/202205001. 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, Signed by Jackson, Donna on 02/16/23 Donna N. Jackson, Acting Chief Reactor Projects Branch 2 Division of Reactor Projects Docket Nos. 05000348 License Nos. NPF2
Enclosure:
As stated
Inspection Report
Docket Number: 05000348 License Number: NPF-2 Report Number: 05000348/2022090 Enterprise Identifier: I20220900006 Licensee: Southern Nuclear Operating Company, Inc.
Facility: Joseph M. Farley Nuclear Plant Location: Columbia Inspection Dates: October 10, 2022 to February 2, 2023 Inspectors: S. Sandal, Senior Reactor Analyst C. Scott, Senior Project Engineer Approved By: Donna N. Jackson, Acting Chief Reactor Projects Branch 2 Division of Reactor Projects Enclosure
SUMMARY The U.S. NRC continued monitoring the licensees performance by conducting a NRC inspection at Joseph M. Farley Nuclear Plant, 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 Inadequate Design Control of the Auxiliary Feedwater System Resulted in the Inoperability of the Turbine-Driven Auxiliary Feedwater Pump Cornerstone Significance Cross-Cutting Report Aspect Section Mitigating Green None (NPP) 71153 Systems NCV 05000348/202205001 Closed EA22095 A self-revealed Green finding and associated non-cited violation (NCV) of 10 CFR Part 50, Appendix B, Criterion III, Design Control, was identified for the licensees failure to adequately translate the design basis of the auxiliary feedwater system (AFW) into procedures and instructions which resulted in the inoperability of the turbine-driven auxiliary feedwater (TDAFW) pump on August 3, 2022.
Additional Tracking Items None.
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.
INSPECTION RESULTS Inadequate Design Control of the Auxiliary Feedwater System Resulted in the Inoperability of the Turbine-driven Auxiliary Feedwater Pump Cornerstone Significance Cross-Cutting Report Aspect Section Mitigating Green None (NPP) 71153 Systems NCV 05000348/202205001 Closed EA22095 A self-revealed Green finding and associated non-cited violation (NCV) of 10 CFR Part 50, Appendix B, Criterion III, Design Control was identified for the licensees failure to adequately translate the design basis of the auxiliary feedwater (AFW) system into procedures and instructions which resulted in the inoperability of the turbine-driven auxiliary feedwater (TDAFW) pump on August 3, 2022.
Description: On August 3, 2022, following a reactor trip and automatic start of the TDAFW pump, operators were directed by licensee procedure FNP1ESP0.1, Reactor Trip Response, revision 39.0, to stop the TDAFW pump. Operators held the hand switches in the OFF position for at least 30 seconds which closed the three steam admission valves and stopped steam flow to the TDAFW pump. The TDAFW pump speed lowered to approximately 145 rpm. When the operators released the hand switches, the steam admission valves automatically reopened as designed because the automatic start signal was still present.
TDAFW pump speed rapidly increased and tripped due to overspeed. To recover the pump, a building operator locally reset the overspeed trip mechanism in accordance with licensee procedure FNP1SOP22.0, Auxiliary Feedwater System revision 83.0, however, the TDAFW pump tripped again due to overspeed. The licensee declared the TDAFW pump inoperable.
In 2011, the licensee modified the TDAFW pump under design change package (DCP) 106086201 by installing a Woodward 505 digital governor controller including a servo motor to control the position of the TDAFW pump governor valve. The Woodward 505 digital governor controller has a protective design feature that will generate a Speed Probes Failed signal when it senses a loss of control, which automatically opens the governor valve to 100 percent, thereby preventing the governor valve from controlling pump speed. This signal is generated when pump speed reaches a pre-defined setpoint of 200 rpm and can only be reset when pump speed lowers to another pre-defined setpoint of 100 rpm. During a routine shutdown of the TDAFW pump, the Speed Probes Failed signal would be generated at 200 rpm, and then reset at 100 rpm, as pump speed decreased.
The inspectors noted two examples where the licensee did not adequately translate the design basis of the AFW into procedures and instructions, following the 2011 modification, which resulted in the inoperability of the TDAFW pump on August 3, 2022.
Example 1: Licensee Procedure FNP1ESP0.1, Reactor Trip Response On August 3, 2022, licensed operators attempted to close the three steam admission valves to the TDAFW pump per licensee procedure FNP1ESP0.1, by holding two control room switches in the STOP position for at least 30 seconds. When the operator released the hand switches, the pump speed was approximately 145 rpm and the Speed Probes Failed signal was still locked into the controller. The steam admission valves went full open as designed because the undervoltage automatic start signal was still present, and the pump tripped on overspeed because the governor valve was locked out at 100 percent open and was prevented from controlling pump speed.
Example 2: Licensee Procedure FNP1SOP22.0. Auxiliary Feedwater System Following the first overspeed trip, a building operator attempted to reset the TDAFW pump by using Figure 1 of licensee procedure FNP1SOP22.0, which is an operator aid for resetting the TDAFW pump trip and throttle valve posted on the wall next to the pump. Following the reset and immediately after opening the trip and throttle valve, the pump tripped again due to overspeed. Step 1 of Figure 1 stated, Request control room close [steam admission valves]
Q1N12HV3235A/26 & Q1N12HV3235B if an autostart signal is not present. Since the automatic start signal for the TDAFW pump was present, operations proceeded to the next steps to reset and open the trip and throttle valve in accordance with the procedure. When the operator opened the trip and throttle valve, the TDAFW pump experienced a second overspeed trip because the governor valve was still open due to the Speed Probe Failure signal and the governor could not modulate to control the steam entering pump.
Licensee procedure NMP-ES044 Design Change Package, version 7.0, was used to implement DCP 1060862601 in 2011 and required an evaluation of plant site considerations including testing, training, maintenance, and operations. The DCP covered each of the items but did not specifically address changes to operating procedures.
The inspectors concluded that on August 3, 2022, the TDAFW pump was rendered inoperable because operating procedure FNP1ESP0.1 did not provide adequate guidance to ensure the Speed Probe Failed signal was reset before operators released the hand switches for the steam admission valves. Additionally, the TDAFW pump was rendered inoperable because the licensee did not update Figure 1 of FNP1SOP22.0 to check the controller for a Speed Probes Failed signal and failed to provide adequate guidance to locally reset the overspeed trip mechanism if an automatic start signal was present, following the modification in 2011.
Corrective Actions: The licensee entered these issues into their corrective action program and revised operating procedures to preclude securing steam flow to the TDAFW pump with an automatic start signal present. Additionally, the licensee established corrective actions to review the design of the TDAFW pump controller and revise additional operating procedures to identify and reset failure signals prior to starting the TDAFW pump.
Corrective Action References: Condition reports 10900508, 10899966, 10899944, 10898654, and 10901729
Performance Assessment:
Performance Deficiency: A performance deficiency was identified for the licensees failure to translate all aspects of the AFW system design into plant operating procedures. Specifically, licensee procedures FNP1ESP0.1, Reactor Trip Response, revision 39.0 and FNP1SOP22.0 Auxiliary Feedwater System, revision 83.0 did not provide adequate guidance to secure steam flow to the TDAFW pump with an automatic start signal and a Speed Probes Failed signal present.
Screening: The inspectors determined the performance deficiency was more than minor because it was associated with the Design Control attribute of the Mitigating Systems cornerstone and adversely affected the cornerstone objective to ensure the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences. Specifically, the licensee failed to provide adequate guidance in licensee procedures FNP1ESP0.1 and FNP1SOP22.0, which rendered the TDAFW pump inoperable on August 3, 2022.
Significance: The inspectors assessed the significance of the finding using IMC 0609 Appendix A, The Significance Determination Process (SDP) for Findings At-Power. The inspectors determined that because the finding could not be screened to be of very low safety significance, a detailed risk evaluation (DRE) was required. Specifically, (1) the procedural deficiencies resulted in the inoperability of the TDAFW pump due to overspeed trips on August 3, 2022, (2) the procedural deficiencies existed for greater than one year and could have resulted in rendering the pump inoperable under certain conditions, and (3) the procedural deficiencies affected the operators capability to recover the pump following overspeed trip. Consequently, the inspectors determined that the finding represented a loss of the probabilistic risk analysis function of one train (i.e., TDAFW pump) of a multi-train technical specification (TS) system for greater than its TS allowed outage time and required a DRE.
A DRE was performed by a regional Senior Reactor Analyst using SAPHIRE Version 8.2.6 and NRC Farley SPAR model Version 8.80. A conditional analysis was performed to evaluate the risk increase due to inability to restore operation of the TDAFW pump following initial successful operation. A one-year condition exposure period was used for the evaluation. No credit was provided for recovery of failed equipment impacted by the finding. The dominant sequences included a plant transient accompanied by a failure of main feedwater, auxiliary feedwater functions and the failure of operator actions to initiate feed and bleed cooling. Other contributing sequences included loss of service water, loss of component cooling water, and weather-related loss of offsite power initiators. The increase in risk was mitigated by the limited number of AFW system failure sequences that would also include plant conditions resulting in shutdown and restart of the TDAFW pump. The analysis determined that the estimated increase in Core Damage Frequency (CDF) and Large Early Release Frequency (LERF) was less than 1E06/year for delta-CDF and less than 1E07/year for delta-LERF, representing a finding of very low safety significance (Green).
Cross-Cutting Aspect: Not Present Performance. No cross-cutting aspect was assigned to this finding because the inspectors determined the finding did not reflect present licensee performance.
Enforcement:
Violation: 10 CFR Part 50, Appendix B, Criterion III, Design Control states, in part, that measures shall be established to assure that applicable regulatory requirements and the design basis are correctly translated into procedures and instructions. Farley Nuclear Plant Updated Final Safety Analysis Report, Section 6.5 states, in part, that the AFW system is designed to supply feedwater to the steam generator during emergency conditions when the normal supply is not available. The TDAFW pump is also designed, in part, to automatically start, during emergency operations, on a loss of power signal. At any point when the two motor-driven AFW pumps are not available, the TDAFW pump is required to provide adequate flow to the steam generators.
Licensee procedure NMP-ES044, Preparation of Design Change Packages, version 7.0, established design control measures to assure, in part that the design bases are correctly translated into procedures and instructions for plant design changes. Specifically, Section A5, DCP Special Design Considerations, of the procedure required an evaluation of plant site considerations including special training and potential negative impacts of the design change on system operation.
Contrary to the above, the licensee failed to ensure the design basis of the AFW system was translated into plant procedures during implementation of the TDAFW electronic governor modification in 2011. Specifically, the licensee failed to evaluate special training needs or negative impacts of the Speed Probes Failed condition of the new governor design on the design basis emergency operation of the TDAFW pump. As such, the licensee failed to revise the following operating procedures:
1. Licensee procedure FNP1ESP0.1, Reactor Trip Response, revision 39.0, did not provide sufficient guidance to secure the TDAFW pump with an automatic start signal present.
2. Operator aid (Figure 1) in licensee procedure FNP1SOP22.0, Auxiliary Feedwater System, revision 83.0, for locally resetting the TDAFW pump trip and throttle valve, did not include guidance to check the status of the electronic governor controller to determine if it was ready to control. As a result, the pump tripped due to overspeed and operators were unable to recover the TDAFW pump.
Enforcement Action: This violation is being treated as a non-cited violation, 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 February 2, 2023, the inspectors presented the NRC inspection results to Site Vice President, Delson Erb, and other members of the licensee staff.
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