IR 05000445/2020001

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Revised Report - Comanche Peak Nuclear Power Plant, Units 1 and 2 -Integrated Inspection Report 05000445/2020001 and 05000446/2020001
ML20353A072
Person / Time
Site: Comanche Peak  Luminant icon.png
Issue date: 12/22/2020
From: O'Keefe N
NRC Region 4
To: Peters K
Vistra Operations Company
References
IR 2020001
Download: ML20353A072 (24)
v • d • e


Text

December 22, 2020

SUBJECT:

REVISED REPORT - COMANCHE PEAK NUCLEAR POWER PLANT, UNITS 1 AND 2 - INTEGRATED INSPECTION REPORT 05000445/2020001 AND 05000446/2020001

Dear Mr. Peters:

On March 31, 2020, the U.S. Nuclear Regulatory Commission (NRC) completed an inspection at Comanche Peak Nuclear Power Plant, Units 1 and 2. On April 2, 2020, the NRC inspectors discussed the results of this inspection with Mr. T. McCool, Site Vice President, and other members of your staff. The results of this inspection are documented in the enclosed report.

The NRC is issuing this revision to the subject report to document inspection of a Unit 2 unplanned outage during the inspection period under Inspection Procedure, 71111.20 -

Refueling and Other Outage Activities, of the attached report. NRC Inspection Report 0500445/2020001 and 0500446/2020001 (ADAMS Accession No. ML20128J555) was initially issued on May 7, 2020, and this revised report replaces it entirely.

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 IV; the Director, Office of Enforcement; and the NRC Resident Inspector at Comanche Peak Nuclear Power Plant, Units 1 and 2.

If you disagree with a cross-cutting aspect assignment in this report, you should provide a response within 30 days of the date of this inspection report, with the basis for your disagreement, to the U.S. Nuclear Regulatory Commission, ATTN: Document Control Desk, Washington, DC 20555-0001; with copies to the Regional Administrator, Region IV; and the NRC Resident Inspector at Comanche Peak Nuclear Power Plant, Units 1 and 2. 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, Cornelius F. Digitally signed by Cornelius F. O'Keefe O'Keefe Date: 2020.12.22 08:33:01-06'00'

Neil F. O'Keefe, Chief Reactor Projects Branch B Division of Reactor Projects Docket Nos. 05000445 and 05000446 License Nos. NPF-87 and NPF-89

Enclosure:

As stated

Inspection Report

Docket Numbers: 05000445 and 05000446 License Numbers: NPF-87 and NPF-89 Report Numbers: 05000445/2020001 and 05000446/2020001 Enterprise Identifier: I-2020-001-0010 Licensee: VISTRA Operations Company, LLC Facility: Comanche Peak Nuclear Power Plant, Units 1 and 2 Location: Glen Rose, TX 76043 Inspection Dates: January 1 to March 31, 2020 Inspectors: J. Ellegood, Senior Resident Inspector D. Antonangeli, Health Physicist B. Baca, Health Physicist N. Day, Resident Inspector N. Greene, Senior Health Physicist J. Melfi, Project Engineer J. O'Donnell, Senior Health Physicist Approved By: Neil F. O'Keefe, Chief Reactor Projects Branch B Division of Reactor Projects Enclosure

SUMMARY

The U.S. Nuclear Regulatory Commission (NRC) continued monitoring the licensees performance by conducting an integrated inspection at Comanche Peak Nuclear Power Plant,

Units 1 and 2, 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

Manual Reactor Trip Due to Loss of both Main Feed Pumps Cornerstone Significance Cross-Cutting Report Aspect Section Initiating Events Green [H.12] - Avoid 71153 NCV 05000446/2020001-01 Complacency Open/Closed A self-revealed finding and associated non-cited violation (NCV) of very low safety significance occurred when the licensee failed to implement procedures for operation of the feed and condensate system as required by Technical Specification 5.4.1.a. Specifically, while adjusting flow to the auxiliary condensers for the Unit 2 main feed pumps, the operators isolated circulating water flow to the condensers, causing a loss of both Unit 2 main feedwater pumps. Control room operators manually insert a plant trip in response to the loss of feedwater.

Additional Tracking Items

Type Issue Number Title Report Section Status LER 05000446/2018-002-01 LER 2018-002-01 for 71153 Closed Comanche Peak, Unit 2,

Automatic Actuation of Auxiliary Feedwater System.

LER 05000446/2019-002-00 LER 2019-002-00 for 71153 Closed Comanche Peak Nuclear Power Plant, Unit 2,

Automatic Actuation of Auxiliary Feedwater System.

PLANT STATUS

Unit 1 began the inspection period at rated thermal power and remained there throughout the inspection period.

Unit 2 began the inspection period at rated thermal power. On January 1, 2020, the licensee inserted a manual trip in response to a loss of both main feed pumps while adjusting circulating water flow to the auxiliary condensers. The licensee took the reactor critical and synchronized to the grid on January 3, 2020. The licensee reached 100 percent power on January 4, 2020 and remained at or near rated thermal power for the remainder of the inspection period.

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. From January 1 - March 19, 2020, the inspectors performed plant status activities described in IMC 2515, Appendix D, Plant Status, and conducted routine reviews using IP 71152, Problem Identification and Resolution. 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 (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 and during that time conducted plant status activities as described in IMC 2515, Appendix D; and observed risk-significant activities when warranted. 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 the cases where it was determined the objectives and requirements could not be performed remotely, management elected to postpone and reschedule the inspection to a later date.

REACTOR SAFETY

71111.01 - Adverse Weather Protection

Impending Severe Weather Sample (IP Section 03.02) (1 Sample)

(1) The inspectors evaluated the adequacy of the overall preparations to protect risk-significant systems from forecasted thunderstorms on January 10, 2020

71111.04 - Equipment Alignment

Partial Walkdown Sample (IP Section 03.01) (1 Sample)

The inspectors evaluated system configurations during partial walkdowns of the following systems/trains:

(1) Unit 2, chemical and volume control system on February 6, 2020

71111.05 - Fire Protection

Fire Area Walkdown and Inspection Sample (IP Section 03.01) (4 Samples)

The inspectors evaluated the implementation of the fire protection program by conducting a walkdown and performing a review to verify program compliance, equipment functionality, material condition, and operational readiness of the following fire areas:

(1) Unit 1, turbine building basement on January 17, 2020
(2) Unit 2, turbine building basement on January 17, 2020
(3) Unit 2, emergency diesel generator A room on January 23, 2020
(4) Service water intake structure building on March 26, 2020

Fire Brigade Drill Performance Sample (IP Section 03.02) (1 Sample)

(1) The inspectors evaluated the onsite fire brigade training and performance during an unannounced fire drill on March 3, 2020

71111.11Q - Licensed Operator Requalification Program and Licensed Operator Performance

Licensed Operator Performance in the Actual Plant/Main Control Room (IP Section 03.01) (1 Sample)

(1) The inspectors observed and evaluated licensed operator performance in the control room during turbine start and synchronization to the grid on January 3, 2020

Licensed Operator Requalification Training/Examinations (IP Section 03.02) (1 Sample)

(1) The inspectors observed and evaluated licensed operators for just in time training for a reactor startup on January 2, 2020

71111.12 - Maintenance Effectiveness

Maintenance Effectiveness (IP Section 03.01) (1 Sample)

The inspectors evaluated the effectiveness of maintenance to ensure the following structures, systems, and components (SSCs) remain capable of performing their intended function:

(1) Unit 2, auxiliary feedwater system on February 25, 2020

71111.13 - Maintenance Risk Assessments and Emergent Work Control

Risk Assessment and Management Sample (IP Section 03.01) (4 Samples)

The inspectors evaluated the accuracy and completeness of risk assessments for the following planned and emergent work activities to ensure configuration changes and appropriate work controls were addressed;

(1) Realignment of the Units 1 and 2 circulating water system on January 15, 2020
(2) Planned yellow risk for Unit 1 auxiliary feedwater valve strokes concurrent with emergent work to restore the Unit 1 emergency diesel generator A to operable status on February 14, 2020
(3) Risk associated with switchyard work and troubleshooting of Unit 2 circulating water pump on February 7, 2020
(4) Risk associated with starting the Unit 2 circulating water pump 2 on March 5, 2020

71111.15 - Operability Determinations and Functionality Assessments

Operability Determination or Functionality Assessment (IP Section 03.01) (4 Samples)

The inspectors evaluated the licensee's justifications and actions associated with the following operability determinations and functionality assessments:

(1) Unit 1, residual heat removal systems A and B, due to increasing pressures as described in condition report CR-2019-009779 on January 9, 2020
(2) Unit 2, emergency diesel generator A, due to a degraded time delay device as described in condition report CR-2020-001295 on February 24, 2020
(3) Unit 2, safety chiller 2-06, tripping due to a shorting bulb socket assembly as described in condition report CR 2020-001502 on March 2, 2020
(4) Unit 2, control rods from potential thermal sleeve cracking as described in Part 21 report LTR-NRC-19-79, and corrective action document TR 2020-1247

71111.19 - Post-Maintenance Testing

Post-Maintenance Test Sample (IP Section 03.01) (4 Samples)

The inspectors evaluated the following post maintenance test activities to verify system operability and functionality:

(1) Repair of disconnected wires and replacement of components in the Unit 2 safeguard sequencer system per Work Order 5840776 on February 20, 2020
(2) Replacement of cell 22 on battery 1DT4 per Work Order 5848383 on January 31, 2020
(3) Repair of failed switch on neutron flux power ranch channel N-42 per Work Order 5866789 on February 28, 2020
(4) As found testing, calibration, and installation of Unit 2 safeguard sequencer B undervoltage relays per Work Order 5666818 on March 4, 2020.

71111.20 - Refueling and Other Outage Activities

Refueling/Other Outage Sample (IP Section 03.01) (1 Sample)

(1) The inspectors evaluated licensee activities during a Unit 2 unplanned outage from January 1-3, 2020.

71111.22 - Surveillance Testing

The inspectors evaluated the following surveillance tests:

Surveillance Tests (other) (IP Section 03.01)

Main article: IP 71111.22
(1) Unit 2, emergency diesel generator monthly load test per Procedure OPT 214B, Diesel Generator Operability Test, Revision 16, on January 22, 2020
(2) Unit 2, at power end of core life reactivity test per Work Order 5659452 on February 10, 2020
(3) Unit 1, monthly control rod exercise surveillance per Work Order 5829754 on January 24, 2020
(4) Unit 1, train A slave relay K609 actuation test per Work Order 5656218 on March 11, 2020

71114.06 - Drill Evaluation

Select Emergency Preparedness Drills and/or Training for Observation (IP Section 03.01)

(1 Sample)

(1) The blue team emergency preparedness drill on February 19,

RADIATION SAFETY

71124.05 - Radiation Monitoring Instrumentation

Walk Downs and Observations (IP Section 02.01) (1 Sample)

The inspectors evaluated the following radiation detection instrumentation during plant walkdowns:

(1) Portable Survey Instruments
  • RM-177, HP-1461
  • RM-177, HP-1113
  • RM-177, HP-1145
  • RM-177, HP-2400
  • RM-177, HP-1464
  • RM-177, HP-1081
  • RM-177, HP-1026
  • AMS-4, HP-2166
  • 3030E, HP-3270 Source Check Demonstration
  • Rad Eye G, HP-3112
  • Telepole, HP-1906
  • Rad Eye GX, HP-4045
  • Ludlum Model 3000, HP-3166 Area Radiation Monitors and Continuous Air Monitors
  • 2-RE-6253
  • 2-RE-6259A
  • 2-RE-6297
  • X-RE-5896A
  • X-RE-5895B
  • 1-RE-6256
  • 1-RE-6295 Personnel Contamination Monitors, Portal Monitors and Small Article Monitors
  • GEM-5, HP-0075
  • GEM-5, HP-0076

Calibration and Testing Program (IP Section 02.02) (1 Sample)

The inspectors evaluated the calibration and testing of the following radiation detection instruments:

(1) Alarm Setpoint and Calibration Method Check of Personnel Contamination Monitors, Portal Monitors and Small Article Monitors
  • GEM-5, HP-0075
  • SAM, HP-0063 Failure to Meet Calibration or Source Check Acceptance Criteria
  • Telepole, HP-1907
  • ARGOS, HP-0065
  • RO-20AA, HP-4123
  • AMS-4, HP-2166

71124.06 - Radioactive Gaseous and Liquid Effluent Treatment

Walk Downs and Observations (IP Section 02.01) (1 Sample)

The inspectors walked down the following gaseous and liquid radioactive effluent monitoring and filtered ventilation systems to assess the material condition and verify proper alignment according to plant design:

(1)

  • Plant Vent Stack Radiation Monitoring System
  • Liquid Waste Processing Radiation Monitoring System
  • Turbine Sump Radiation Monitoring System
  • Station Service Water to Discharge Canal Radiation Monitoring System Calibration and Testing Program (Process & Effluent Monitors) (IP Section 02.02) (1 Sample)

The inspectors reviewed the following gaseous and liquid effluent monitor instrument calibrations and tests:

(1)

  • WO 5360001, X-RE-5567A, South Plant Vent Stack Radiation Monitor Calibration, 07/30/2018
  • WO 5590739, X-RE-5570B, North Plant Vent Stack WRGM Radiation Monitor Calibration, 10/01/2019
  • WO 5585319, X-RE-5253, Liquid Waste Processing Discharge Radiation Monitor Calibration, 10/28/2019
  • WO 5556086, 2-RE-5100, Turbine Sump 2-04 Radiation Monitor Calibration, 06/12/2019
  • WO 5421935, 1-RE-4269, Unit 1 Station Service Water Train A to Discharge Canal Radiation Monitor Calibration, 10/24/2018
  • WO 5631300, 1-RE-4270, Unit 1 Station Service Water Train B to Discharge Canal Radiation Monitor Calibration, 01/14/2020
  • WO 5576336, 2-RE-4269, Unit 2 Station Service Water Train A to Discharge Canal Radiation Monitor Calibration, 09/25/2019
  • WO 5447947, X-FT-5288, LWPS LHMT X-01/X-02 Discharge to VD System Flow Transmitter Calibration, 09/27/2018

Sampling and Analysis (IP Section 02.03) (1 Sample)

The inspectors reviewed the following:

(1) Radioactive Effluent Sampling and Analysis Activities
  • Plant Ventilation Weekly Sampling, 01/27/2020
  • Containment Ventilation Sampling, 01/30/2020 Effluent Discharge Permits
  • G2018-034, Unit 1 Containment Vent, 02/27/2018
  • G2018-208, Plant Vent Stack B, 12/09/2018
  • G2018-210, Non-Routine Gas Normal, 12/10/2018
  • G2019-046, Plant Vent Stack B, 03/12/2019
  • G2019-193, Unit 2 Containment Vent, 11/24/2019
  • G2019-216, Plant Vent Stack A, 12/31/2019
  • L2018-023, Plant Effluent Tank 1, 07/05/2018
  • L2018-040, Plant Effluent Tank 2, 10/24/2018
  • L2018-051, Low Volume Waste Pond (LVWP), 12/01/2018
  • L2019-016, Plant Effluent Tank 1, 02/14/2019
  • L2019-055, Squaw Creek Reservoir, 08/01/2019
  • L2019-072, Plant Effluent Tank 2, 12/12/2019

Instrumentation and Equipment (IP Section 02.04) (1 Sample)

The inspectors reviewed the following radioactive effluent discharge system surveillance test results:

(1)

  • WO 5319196, Primary Plant Ventilation Exhaust Filter Unit X-16 - Carbon Analysis B Train, 01/13/2018
  • WO 5377734, Primary Plant Ventilation Exhaust Filter Unit X-01 - ESF Filter Test A Train, 10/31/2018
  • WO 5431297, Primary Plant Ventilation Exhaust Filter Unit X-02 - ESF Filter Test B Train, 11/07/2018

Analysis B Train, 09/18/2019 Dose Calculations (IP Section 02.05) (1 Sample)

The inspectors reviewed the following to asses public dose:

(1) Liquid and Gaseous Discharge Permits
  • G2018-034, Unit 1 Containment Vent, 02/27/2018
  • G2018-208, Plant Vent Stack B, 12/09/2018
  • G2018-210, Non-Routine Gas Normal, 12/10/2018
  • G2019-046, Plant Vent Stack B, 03/12/2019
  • G2019-193, Unit 2 Containment Vent, 11/24/2019
  • G2019-216, Plant Vent Stack A, 12/31/2019
  • L2018-023, Plant Effluent Tank 1, 07/05/2018
  • L2018-040, Plant Effluent Tank 2, 10/24/2018
  • L2018-051, Low Volume Waste Pond (LVWP), 12/01/2018
  • L2019-016, Plant Effluent Tank 1, 02/14/2019
  • L2019-055, Squaw Creek Reservoir, 08/01/2019
  • None were available for review during this inspection

71124.07 - Radiological Environmental Monitoring Program

Site Inspection (IP Section 02.01) (1 Sample)

The inspectors evaluated the radiological environmental monitoring program implementation.

(1) The inspectors reviewed the following:

Walkdowns, Calibrations, and Maintenance Record Review

  • Air sampling stations: A1, A2, A3, A4, A5, A6, A7, A8
  • Thermoluminescent dosimeter (TLD) monitoring stations: R1, R4, R11, R13, R22, R25, R27, R29, R30, R36
  • Calibrations of selected air sample pumps: 2178, 2196B, 2214, and 2224 Environmental Sample Collections and Preparation Observation
  • Air particulate (A1, A2, A3, A4, A5, A6, A7, A8)
  • Air charcoal (A1, A2, A3, A4, A5, A6, A7, A8)
  • Broad leaf (BL1, BL2, BL3)
  • Surface water (SW1, SW2, SW3, SW4, SW5)

Licensee Actions in Response to Missed Sample, Inoperable Sampler, Lost Thermoluminescent Dosimeter (TLD) or Anomalous Measurement The inspectors reviewed the licensee's response to 13 missing or anomalous TLD results. The inspectors reviewed 6 inoperable samplers as noted in corrective action documents since May 2017 and noted in the 2017 and 2018 Annual Environmental Operating Reports. The majority of inoperable samplers were attributed to loss of power due to external events, such as weather and power line work.

Sampling Program for the Potential of Licensed Material Entering Groundwater

  • Groundwater Monitoring Wells: 9, 10, 11, 12, 14, 15, 16, 19, 25, CP-A, CP-B, CP-C

Groundwater Protection Initiative (GPI) Implementation (IP Section 02.02) (1 Sample)

(1) The inspectors evaluated the licensee's voluntary groundwater protection initiative.

A few observations were as follows:

  • The general maintenance and material condition of the groundwater monitoring wells was adequate with the general area around the well was kept clear of any obstructions.
  • Most monitoring wells had enough water for samples to be taken.
  • Monitoring well locations 11 and CP-A had results of 835 and 1700 pCi/L, respectively, which are both below their lower limit of detection (LLD)requirements. The remaining well location samples all tested below the minimum detectable activity.
  • The licensee implemented additional surface water sampling of the drainage flow catch basin to track the potential impact of a water treatment filtered water storage tank leak. The licensee has corrective actions in progress to address the identified leak.

OTHER ACTIVITIES - BASELINE

===71151 - Performance Indicator Verification The inspectors verified licensee performance indicators submittals listed below:

IE01: Unplanned Scrams per 7000 Critical Hours Sample (IP Section 02.01) ===

Main article: IP 71151
(1) Unit 1 January 1, 2019, to December 31, 2019
(2) Unit 2 January 1, 2019, to December 31 2019 IE03: Unplanned Power Changes per 7000 Critical Hours Sample (IP Section 02.02)

(2 Samples)

(1) Unit 1 January 1, 2019, to December 31, 2019
(2) Unit 2 January 1, 2019, to December 31, 2019

IE04: Unplanned Scrams with Complications (USwC) Sample (IP Section 02.03) (2 Samples)

(1) Unit 1 January 1, 2019, to December 31, 2019
(2) Unit 2 January 1, 2019, to December 31, 2019

71153 - Follow-up of Events and Notices of Enforcement Discretion Event Follow-up (IP Section 03.01)

Main article: IP 71153
(1) The inspectors evaluated licensee response to a Unit 2 reactor trip on January 1, 2020.

Event Report (IP Section 03.02) (2 Samples)

The inspectors evaluated the following licensee event reports (LERs):

(1) LER 05000446/2019-002-00, Automatic Actuation of Auxiliary Feedwater System (ADAMS Accession No. ML19199A033). The inspectors determined that it was not reasonable to foresee or correct the cause discussed in the LER; therefore, no performance deficiency was identified. The inspectors did not identify a violation of NRC requirements.
(2) LER 05000446/2018-002-01, Automatic Actuation of Auxiliary Feedwater System (ADAMS Accession No. ML19199A032). The inspectors determined that it was not reasonable to foresee or correct the cause discussed in the LER; therefore, no performance deficiency was identified. The inspectors did not identify a violation of NRC requirements.

INSPECTION RESULTS

Manual Reactor Trip Due to Loss of both Main Feed Pumps Cornerstone Significance Cross-Cutting Report Aspect Section Initiating Events Green [H.12] - Avoid 71153 NCV 05000446/2020001-01 Complacency Open/Closed A self-revealed finding and associated non-cited violation (NCV) of very low safety significance occurred when the licensee failed to implement procedures for operation of the feed and condensate system as required by Technical Specification 5.4.1a. Specifically, while adjusting flow to the auxiliary condensers for the Unit 2 main feed pumps, the licensee isolated circulating water flow to the condensers, causing a loss of both Unit 2 main feedwater pumps. Control room operators manually insert a plant trip in response to the loss of feedwater.

Description:

On January 1, 2020, the Comanche Peak on-shift operations crew decided to secure a running circulating water pump for Unit 2. Although securing the pump was not on the plan of the day schedule, the shift manager added the activity into the shift's work activities to support planned work the following week. The inspectors noted that the activity would use normal circulating water system operating Procedure SOP-310B, Circulating Water, Revision 18, and the work schedule provided enough time to prepare for and conduct the evolution. The procedure was structured to secure one circulating water pump, adjust flow as needed to the main condenser, and then to adjust flow to the two main feedwater pump auxiliary condensers. There are two steam driven main feedwater pumps.

The auxiliary condensers support operation of the two main feedwater pumps by condensing the steam used by the feedwater pump turbines. Flow was being adjusted to optimize plant thermal efficiency.

The crew successfully secured the circulating water pump and adjusted main condenser flow.

The crew then proceeded to the auxiliary condensers to adjust circulating water flow. A field operator was stationed at each of the two auxiliary condenser outlet valves and a third field operator was communicating with the main control room staff. In addition, a senior reactor operator provided local oversight of the evolution. The crew intended to adjust the throttle position of the circulating water with a final position directed by the reactor operator in the control room. The reactor operator directed the valve operators to slowly close their respective valves (simultaneously) to his mark while he monitored water box outlet temperature. The valves were initially in a throttled position at the start and they reached the fully closed position shortly after starting. Without any flow to the auxiliary condensers, both main feedwater pumps automatically tripped on low vacuum to protect the pumps. Control room staff immediately inserted a manual trip from 100 percent power. The control room operators stabilized the plant in mode 3 using Emergency Procedure E-0, Reactor Trip and Safety Injection, and normal operating procedures without further issue.

Personnel directly involved in the task failed to recognize that condenser vacuum would respond quickly to reduced cooling water flow, but there would be delays before condensate temperature would be reduced as the circulating water was adjusted due to mixing. In addition, the personnel directly involved in the task did not recognize that the auxiliary condenser outlet valves were two turns from full closed at the start of the evolution. These factors led the field operators to erroneously fully close the valves prior to control room direction to stop throttling the valves. The inspectors noted that the auxiliary condenser outlet valves had large valve position indicators to provided system configuration information to the local operators.

Comanche Peak performed a root cause evaluation to understand the event. The review identified several weaknesses in crew performance that contributed to the event. Weakness identified as the root cause were an over-reliance on process (i.e., procedures) coupled with a failure to address gaps in behaviors and standards. This resulted in a lack of critical thinking by plant staff as well as a failure to understand and address risks associated with the proposed activities. During this evolution, operators failed to recognize the potential to lose vacuum for the feed pumps due to a lack in understanding system operation and fundamentals. The crew considered the throttling of cooling water flow to be a routine activity and, therefore, the task preparations did not trigger a focused brief to discuss the evolution.

However, changing the circulating water pump configuration only occurs during winter months to allow for maintenance on the pumps. The operators assigned to the task had a lack of proficiency as none of the operators directly involved with adjusting flow on the auxiliary condensers had secured a circulating water pump before. Furthermore, the operations shift included three operators that had performed this evolution previously, but none were directly involved in adjusting flow to the auxiliary condensers. The inspectors noted that their direct involvement could have reduced the likelihood of an error during the evolution. In addition, periodic throttling of the auxiliary condenser outlet valve flow occurred with regularity; however, the adjustments were normally made in small increments with time between valve movements to allow the system to equilibrate.

The inspectors performed walkdowns of the evolution after the event, interviewed the personnel involved, reviewed plant operating procedures, and reviewed the root cause evaluation. The inspectors noted that although Comanche Peak used the correct procedure and the procedure had been used successfully previously, weaknesses in preparation for the activity and oversight led to the loss of the feed pumps. Weaknesses included a failure to recognize the risks associated with throttling auxiliary condenser circulating water flow, adjusting flow to two condensers simultaneously, giving a non-standard order (throttle slowly closed to my mark), not understanding the throttling characteristics of a butterfly valve, not establishing the initial valve positions and closely monitoring the position as it was adjusted, not monitoring the most applicable system parameters for the expected changes, and failure to recognize and compensate for a lack of proficiency of the operators in performing this evolution.

Corrective Actions: As an immediate corrective action, Comanche Peak operators tripped the Unit 2 reactor and stabilized the plant in mode 3. Personnel involved were removed from on-shift duties pending remedial training. Longer term actions included additional oversite of operations activities. Additional actions are discussed on AR 2020-00008.

Corrective Action References: CR-2020-00008

Performance Assessment:

Performance Deficiency: The failure to adequately supervise component manipulations and control system parameters within procedure limits while adjusting circulating water flow through the auxiliary condensers was a performance deficiency. Specifically, operators failed to adequately prepare for adjusting circulating water flow to the Unit 2 main feedwater pump auxiliary condenser outlet valves, which caused inappropriate valve manipulation during the evolution and created a condition that required a Unit 2 reactor trip.

Screening: The inspectors determined the performance deficiency was more than minor because it was associated with the human performance attribute of the Initiating Events Cornerstone and adversely affected the cornerstone objective to limit the likelihood of events that upset plant stability and challenge critical safety functions during shutdown as well as power operations. Specifically, the failure to adequately supervise component manipulations and maintain system parameters within procedural limits led to the loss of both running main feedwater pumps and a plant trip.

Significance: The inspectors assessed the significance of the finding using Appendix A, The Significance Determination Process (SDP) for Findings At-Power. In accordance with IMC 0609, Appendix A, Exhibit 1, the inspectors determined that the finding required a detailed risk evaluation because the loss of feedwater caused operators to manually trip the reactor and the loss of main feedwater constituted a loss of mitigation equipment used to transition the plant to a stable shutdown condition.

The senior reactor analyst performed a detailed risk evaluation by treating the finding as an initiating event and using the conditional core damage probability for a loss of main feedwater as called for in Section 8.0, Initiating Event Analyses, of the Risk Assessment of Operational Events Handbook. The analyst used Comanche Peak SPAR model version 8.58, run on SAPHIRE, software version 8.2.1, for the evaluation.

The model was modified to reflect probabilistic recovery of a main feedwater pump. To accomplish this, the analyst adjusted Basic Event MFW-XHE-XL-TRIP, Operator Fails to Restart Main Feedwater Flow, used in Fault Tree MFW, Main Feedwater System, from TRUE to a SPAR-H human reliability model derived value of 4.40E-2. In this human reliability analysis, the analyst assigned high stress to both diagnosis and action and moderate complexity to both diagnosis and action for the recovery. All other performance shaping factors were set to nominal. Also, the analyst credited the use of the licensees diverse and flexible coping strategies (FLEX) equipment. Performance of the initiating event analysis with these modifications yielded an estimate of the increase in core damage frequency of 7.8E-7 per year from internal events. Loss of main feedwater events were the dominant sequences and were mitigated by the auxiliary feedwater system.

The analyst noted that this detailed risk assessment evaluates an actual event in which no external events occurred. Additionally, the period that the events impacted plant equipment was small enough that the probability of an external initiator occurring during this time would be negligible. Therefore, the analyst assumed that the risk from external events, given the subject performance deficiency, was essentially zero. This resulted a total estimate in the increase of core damage frequency of 7.8E-7 per year, making the finding of very low safety significance (Green).

The increase in large early release frequency from this finding was determined to be of very low safety significance using IMC 0609, Appendix H, Containment Integrity Significance Determination Process, because loss of main feedwater sequences screen as having low safety significance in pressurized water reactors with large dry containments.

Cross-Cutting Aspect: H.12 - Avoid Complacency: Individuals recognize and plan for the possibility of mistakes, latent issues, and inherent risk, even while expecting successful outcomes. Individuals implement appropriate error reduction tools. The licensee identified in their root cause analysis that operations did not recognize nor understand the risks associated with the evolution. The inspectors concluded that as a result, operators did not plan for the possibility of mistakes or implement appropriate error reduction tools.

Enforcement:

Violation: Technical Specification Section 5.4.1.a requires, in part, that written procedures shall be established, implemented, and maintained covering the applicable procedures recommended in Regulatory Guide 1.33, Revision 2, Appendix A, February 1978. NRC Regulatory Guide 1.33, Revision 2, Appendix A, Section 3, addresses Procedures for Startup, Operation, and Shutdown or Safety-Related PWR Systems and Section 3.K, addresses Feedwater System. The licensee established Procedure SOP-310B, Circulating Water, Revision 18, to address operation of the circulating water system, including adjusting flow to the auxiliary condensers which support operation of main feedwater system.

Procedure SOP-310B, Revision 18, step 5.3.7, requires operators to slowly adjust the auxiliary condenser differential pressure to between 1- and 10 feet H2O. Contrary to the above, on January 1, 2020, the licensee failed to slowly adjust the auxiliary condenser differential pressure and maintain it between 1- and 10 feet H2O when operators fully closed the valves, causing a condition (dual feedwater pump trips on low vacuum) that required a reactor trip.

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 January 31, 2020, the inspectors presented the radiation safety exit meeting inspection results to Mr. T. McCool, Site Vice President, and other members of the licensee staff.
  • On April 2, 2020, the inspectors presented the integrated inspection results to Mr. T. McCool and other members of the licensee staff.

DOCUMENTS REVIEWED

Inspection Type Designation Description or Title Revision or

Procedure Date

71111.04 Procedures SOP-103B Chemical and Volume Control System 13

71111.05 Fire Plans FPI-105B U-2, train B Diesel generator and Equipment Elevation, 810' 2

Miscellaneous Fire Hazard Analysis Report Sections 5.9.7 and 5.6 32

Drill 20-15-01 Fire Drill Scenario for EDG 2-02 810' Fuel Oil Transfer Pit March 3,

20

71111.12 Corrective Action TR-YYYY-NNNN 2016-008019

Documents

Miscellaneous Maintenance Rule Summary Report for Unit 1 and Unit 2 02/18/2020

Auxiliary Feedwater

Auxiliary Feedwater System Status 2nd Quarter

FY19

71111.13 Drawings E2-0026 6.9KV Three Line Diagram Normal Buses 13

Miscellaneous STI-600.01-1 Guarded Equipment Management Posting Log February 12,

20

Procedures SOP-310B Circulating water System 18

Work Orders 5835726 Auxiliary Feedwater Pump Turbine 2-01Govenor Stroke 02/13/2020

71111.15 Corrective Action CR 2019-9530 12/13/2019

Documents TR 2020-1247 February 19,

20

Drawings M2-2760 Diesel Engine Start/Stop Logic 15

Operability FSAR Table 8.3-1, Loading Requirements for Loss of 104

Evaluations Coolant Accident Coincident with Loss of Offsite Power

CR- 2020-001295

71111.19 Corrective Action CR-YYYY-NNNN 2019-009453

Documents IR-2020-001597 Multiple Relays Out of Tolerance on Unit 2 Train B

Sequencer

Procedures INC-7393A CH Cal Neutron Flux Power Range ION Current Gain and 6

Summing Level Amplifier

MSE-S2-0673B Unit 2 Train B Sequencer Under Voltage Relay Surveillance 5

Work Orders WO 5666818 Perform MSE-S2-0673B, TR B Sequencer UV Relay

WO 5840776 Troubleshoot and Repair Sequence Alarm Circuit as

documented in IR-2019-009453

Inspection Type Designation Description or Title Revision or

Procedure Date

WO 5848383 Replace Cell 22 on BT1D4 at Power

WO 5866715 Perform CCAL IAW INC-7393A

WO 5866789 Troubleshoot test signal going to zero described in CR 2020-

001447

71111.20 Miscellaneous BEACON 3D Reactivity Projection for Unit 2 Forced Outage 01/01/2020

Startup

71111.22 Procedures ETP-106 Monthly RCCA Repositioning 1

OPT-106A Control Rod Exercise 12

OPT-467A Train A Safeguards Slave relay K609 Actuation Test Revision 5

Work Orders WO 5656218 Solid State Protection System Slave Relay Test March 11,

20

WO 5659452 Perform NUC 202 AT-Power MTC Measurement

WO 5829754 OPT-106A, Control Rod Exercise Test

WO 5846000 Monthly RCCA Repost ETP-106

WO 5852752 IR-2020-000542 Troubleshoot 2-01 EDG Volt Reg TRBL

71114.06 Miscellaneous ERO team Exercise February 9,

20

71124.05 Calibration 3443188 X-RE-5700 ICI-4998, CCAL FB VNT EXH 06/24/2009

Records 3648653 2-RE-6297, ICI-4961 Channel Calibration 09/30/2010

391556 1-RE-6295 ICI-4961, CCAL 03/16/2009

4373552 1-RE-6295 ICI-4961, CCAL 04/12/2016

4374577 2-RE-6297 ICI-4961, CCAL 05/10/2017

26655 X-RE-5700 ICI-4998, CCAL FB VNT EXH 01/22/2015

20934 1-RE-6256 ICI-4959 CCAL HRAM 06/09/2015

5371788 X-RE-5701 INC-4915X, CCAL AB VNT GPRM 07/18/2019

22342 1-RE-6290A INC-7079, CCAL CNTMT HRRM 05/16/2019

22458 1-RE-6290B INC-7079, CCAL CNTMT HRRM 05/02/2019

26341 1-RUK-2326A/2328A INC-4916 CCAL 07/17/2019

ASCAN WBC System Calibration Data Package 11/20/2019

FSCAN WBC System Calibration Data Package 09/12/2019

HP-0058 Argos/Sirius Calibration Data Sheet 11/10/2019

HP-0063 NE Technology SAM Calibration Data Sheet 10/22/2018

HP-0075 GEM-5 Calibration Data Sheet 02/04/2019

Inspection Type Designation Description or Title Revision or

Procedure Date

HP-1206 Ludlum Model 177 Frisker Calibration Data Sheet 01/27/2020

HP-2166 AMS-4 Calibration Data Sheet 10/04/2019

HP-4124 Thermo RO-20AA Calibration Data Sheet 01/29/2020

HP-5002 Low Volume Air Sampler Calibration Data Sheet 10/12/2018

HP-711812 RDS-31 Calibration Data Sheet 10/07/2019

Corrective Action CR-YYYY-NNNN 2011-006222, 2016-001350, 2018-003694, 2018-006522,

Documents 2018-006631, 2018-007217, 2019-000184, 2019-001550,

2019-004125, 2019-004570, 2019-005318, 2019-007716,

2019-008045, 2019-008114, 2019-008129

TR-YYYY-NNNN 2018-006999, 2018-007197, 2018-007846, 2019-001511,

2019-003201, 2019-003405, 2019-003992, 2019-004146,

2019-004149, 2019-004221, 2019-005656, 2020-000063

Corrective Action CR-YYYY-NNNN 2020-000750, 2020-000783, 2020-000814

Documents

Resulting from

Inspection

Miscellaneous 1-RE-6290A Last Detector Primary Calibration 05/15/2019

19-001 through Calibration Well Source Charts 08/08/2019

19-007

2Qtr FY19 CPNPP System Status: Radiation Monitoring

T190990 RadCal 2026C and 1800cc, 180cc, and 6cc detectors 05/29/2019

Procedures CLI-782 APEX Gamma Spectroscopy Counting System 2

ICI-4959 Channel Calibration - High Range Area Radiation Monitors 4

ICI-4961 Channel Calibration - Digital High Range Area Monitors 4

ICI-4998 Channel Calibration - Gas Process Radiation Monitor 4

INC-7079 Channel Calibration - 6

Containment High Range Radiation Monitor Channels

1-RE-6290A/B and 2-RE-6290A/B

RPI-301 Portable Survey Instruments 13

RPI-800 Control of Radiation Protection Equipment 17

RPI-802 Performance of Source Checks 28

RPI-862 Calibration of the Argos/Sirius Personnel Contamination 14

Monitor and Gem-5 Gamma Exit Monitor

STA-619 Administrative Control of Digital Radiation Monitoring System 7

Inspection Type Designation Description or Title Revision or

Procedure Date

STA-650 General Health Physics Plan 8

STA-658 Radiation Protection Equipment Calibration Program 12

STA-677 Preventative Maintenance Program 13

STA-700 Surveillance Frequency Control Program 1

STI-677.01 PM Change Processing 2

Self-Assessments EVAL-2018-006 Work Management/Radiation Protection Audit 08/02/2018

EVAL-2019-007 Chemistry Control and Chemistry Measurement & Analysis 11/21/2019

71124.06 Calibration WO 5360001 X-RE-5567A, South Plant Vent Stack Radiation Monitor 07/30/2018

Records Calibration

WO 5421935 1-RE-4269, Unit 1 Station Service Water Train A to 10/24/2018

Discharge Canal Radiation Monitor Calibration

WO 5447947 X-FT-5288, LWPS LHMT X-01/X-02 Discharge to VD System 09/27/2018

Flow Transmitter Calibration

WO 5556086 2-RE-5100, Turbine Sump 2-04 Radiation Monitor Calibration 06/12/2019

WO 5576336 2-RE-4269, Unit 2 Station Service Water Train A to 09/25/2019

Discharge Canal Radiation Monitor Calibration

WO 5585319 X-RE-5253, Liquid Waste Processing Discharge Radiation 10/28/2019

Monitor Calibration

WO 5590739 X-RE-5570B, North Plant Vent Stack WRGM Radiation 10/01/2019

Monitor Calibration

WO 5631300 1-RE-4270, Unit 1 Station Service Water Train B to 01/14/2020

Discharge Canal Radiation Monitor

Corrective Action CR-YYYY-NNNN 2019-008687, 2019-008794

Documents TR-YYYY-NNNN 2017-000757, 2018-003362, 2019-001642, 2019-005866,

2019-006713, 2019-008605

Corrective Action TR-YYYY-NNNN 2020-000766, 2020-000815, 2020-000817

Documents TR-YYYY-NNNN 2020-000766, 2020-000815, 2020-000817

Resulting from

Inspection

Miscellaneous CPSES Offsite Dose Calculation Manual, Unit 1 and Unit 2 34

2017 Annual Radioactive Effluent Release Report 03/12/2018

2018 Annual Radioactive Effluent Release Report 04/20/2019

G2018-034 Gaseous Discharge Permit - Unit 1 Containment Vent 02/27/2018

G2018-208 Gaseous Discharge Permit - Plant Vent Stack B 12/09/2018

Inspection Type Designation Description or Title Revision or

Procedure Date

G2018-210 Gaseous Discharge Permit - Non-Routine Gas Normal 12/10/2018

G2019-046 Gaseous Discharge Permit - Plant Vent Stack B 03/12/2019

G2019-193 Gaseous Discharge Permit - Unit 2 Containment Vent 11/24/2019

G2019-216 Gaseous Discharge Permit - Plant Vent Stack A 12/31/2019

L2018-023 Liquid Discharge Permit - Plant Effluent Tank 1 07/05/2018

L2018-040 Liquid Discharge Permit - Plant Effluent Tank 2 10/24/2018

L2018-051 Liquid Discharge Permit - Low Volume Waste Pond (LVWP) 12/01/2018

L2019-016 Liquid Discharge Permit - Plant Effluent Tank 1 02/14/2019

L2019-055 Liquid Discharge Permit - Squaw Creek Reservoir 08/01/2019

L2019-072 Liquid Discharge Permit - Plant Effluent Tank 2 12/12/2019

Procedures CHM-170 Liquid and Gaseous Effluent Program 4

CHM-230 Guidelines for Sample Collection 3

CLI-744 Radioactive Effluent Pre-Release Permit Processing 2

CLI-745 Radioactive Effluent Post-Release Permit Processing and 3

Surveillance Tracking

STA-603 Control of Station Radioactive Effluents 21

STA-619 Administrative Control of the Digital Radiation Monitoring 7

System

STA-677 Preventive Maintenance Program 13

Self-Assessments EVAL-2019-007 Radioactive Waste, Effluents, Environmental, and Chemistry 11/21/2019

Programs

Work Orders WO 5319196 Primary Plant Ventilation Exhaust Filter Unit X-16 01/31/2018

WO 5377734 Primary Plant Ventilation Exhaust Filter Unit X-01 10/03/2018

WO 5431297 Primary Plant Ventilation Exhaust Filter Unit X-02 11/17/2018

WO 5558463 Primary Plant Ventilation Exhaust Filter Unit X-02 09/18/2019

71124.07 Corrective Action CR-YYYY-NNNN 2018-001574, 2018-001611, 2018-001760, 2018-004523,

Documents 2019-002077

TR-YYYY-NNNN 2018-001867, 2018-004228, 2019-001642, 2019-007287

2019-008284, 2019-009052, 2019-009165

Corrective Action CR-YYYY-NNNN 2020-000748

Documents

Resulting from

Inspection

Inspection Type Designation Description or Title Revision or

Procedure Date

Miscellaneous 2017 Annual Radiological Environmental Operating Report 04/30/2018

2018 Annual Radiological Environmental Operating Report 04/01/2019

NUPIC Audit GEL Laboratories (JQA-14-097) 05/29/2014

23724

NUPIC Audit GEL Laboratories (NOD-19-018) 08/29/2019

24747

(NOV2019-069)

ODCM Comanche Peak Steam Electric Station Offsite Dose 34

Calculation Manual Unit 1 and Unit 2

RPI-714-1- 2018 Land Use Census 07/31/2018

20180715

RPI-714-1- 2019 Land Use Census 07/25/2019

20190620

Procedures RPI-538 Process Environmental Badges 9

RPI-710 Radiological Environmental Monitoring, Sampling, and 22

Analysis Program

RPI-713 Collection, Preparation, and Shipment of Radiological 19

Environmental Samples

RPI-714 Land Use Census 6

RPI-888 Calibration of Portable Air Sample Equipment 5

STA-653 Contamination Control Program 20

STA-654 Groundwater Protection Program 9

Self-Assessments EVAL-2019-007 Radioactive Waste, Effluents, Environmental, and Chemistry 11/21/2019

Programs

Work Orders WO- 4938991, 4965490, 5052258, 5080201, 5490927,

5651858, 5654059, 5654081, 5654093, 5654106,

5654119, 5654136, 5659602, 5659645, 5667801,

5736155, 5736168, 5736197, 5736232, 5736248,

5736282, 5736299, 5741625, 5747140

21

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