ML22224A246

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Entergy Slides for Regulatory Conference (Enc 3)
ML22224A246
Person / Time
Site: Waterford Entergy icon.png
Issue date: 08/19/2022
From:
Entergy Operations
To:
NRC Region 4
References
EA-22-033
Download: ML22224A246 (36)
v • d • e


Text

Waterford Steam Electric Station, Unit 3 Condenser Wide Range Gas Monitor Regulatory Conference July 29, 2022

Introductions & Agenda John Lewis - Regulatory Assurance Manager, Waterford 3 01

3 Agenda Section Presenter Management Overview John Ferrick Issue Identification, Root Cause, Corrective Actions & Extent of Condition Billy Steelman Operator Actions Stephen Smith Emergency Planning Dean Burnett Enforcement Perspective John Lewis Closing Remarks John Ferrick

Management Overview John Ferrick - Site Vice President, Waterford 3 02

5 Management Overview

  • Licensee Identified
  • Prompt and timely corrective actions
  • Not indicative of current performance Failure to maintain the correct function of the Condenser Wide Range Gas Monitor (WRGM) is a performance deficiency Failure to maintain correct calibration and engineering conversion factors did not adversely impact the ability to accurately and timely classify an emergency condition and did not adversely impact the capability to adequately estimate offsite releases No Degraded Risk Significance Planning Standard Function

6

Issue Identification, Root Cause, Corrective Actions &

Extent of Condition 03 Billy Steelman - Strategic Engineering Manager, Waterford 3

8 Condition Description Problem Statement: From January 2011 to February 2022, the Condenser WRGM mid and high-range detectors were out of calibration

  • Licensee identified condition / Good questioning attitude
  • Technical Conscience / Cross Functional Teamwork
  • RD-72 detector is a Cadmium Telluride solid state detector used to detect mid and high range concentrations
  • Immediate notification to shift manager and emergency planning
  • Calibration requirements are not specifically called out in vendor documentation

9 Root Cause Root Cause:

Procedure revisions in 1985 removed critical steps and equipment requirements which supported replacement, calibration, and troubleshooting issues for specific detectors Legacy Issue:

  • Procedure allowed use of a scalar device instead of multi-channel analyzer
  • Impact on future detector replacements was not recognized RD-72 detector

10 Timeline 1985 - Procedural latent error introduced by deleting new detector calibration information Allowed calibration issue to occur for future detector replacement 1986 - EPLAN procedure added the Condenser WRGM to Site Area Emergency (SAE)

Classification 2011 - Condenser WRGM calibration error introduced Detector replaced and not calibrated using a multi-channel analyzer 2021 - NEI 99-01, Rev. 6 implemented This EPLAN version removed the Condenser WRGM for Emergency Action Levels (EALs) 2022 - Calibration issue identified (January)

Condenser WRGM calibrated, and condition corrected (February)

11 Corrective Actions

  • Condenser WRGM calibrated correctly
  • Vendor support obtained to validate issue and support resolution
  • Condenser WRGM procedure updated to correct detector replacement calibration methodology
  • Extent of Condition procedures for Plant Stack and Fuel Handling Building WRGMs were updated to correct detector replacement calibration methodology
  • EPLAN-related detectors have either been calibrated or a compensatory measure has been established
  • Organizational & Programmatic - latent procedure issue

12 Root Cause Safety Significance Condenser WRGM Design Basis Steam Generator Tube Rupture (SGTR) is limiting event for the Condenser WRGM Design Basis SGTR does not credit the Condenser WRGM for accident mitigation Emergency Operating Procedures drive to cool down the Reactor Coolant System to isolate the affected Steam Generator (SG) which limits the amount of radiological activity being released through the Condenser EAL Classification and Dose Assessments would not result in an Over-Classification because the affected SG would be isolated from the Condenser

13 Root Cause - Extent of Condition Extent of Condition Findings: No adverse impact on offsite release estimates or ability to classify an emergency condition

Operator Actions 04 Stephen Smith - Assistant Operations Manager Senior License Holder - Waterford 3

15 Plant Response to a Steam Generator Tube Rupture

16 Plant Response to a Steam Generator Tube Rupture

17 SGTR Mitigation Strategy

18 Condenser WRGM isolation from SGTR SGTR mitigating strategy results in isolation of the Condenser WRGM from affected Steam Generator

19 Monitors for Early Diagnosis of a SGTR Radiation Monitors to diagnose primary to secondary leakage:

The Air Evacuation PIG (Particulate, Iodine, Gas) Monitor detects small levels of primary to secondary leakage and monitors the condenser air evacuation system non-condensable gases directly from the discharge of the B & C Air Evacuation pumps Main Steam Line N16 (Nitrogen-16) Monitors are used to detect and display primary to secondary leakage specific to each Steam Generator

20 Additional radiation monitors to diagnose primary to secondary leakage:

Blowdown Radiation Monitor - Samples the combined blowdown sample stream for activity Main Steam Radiation Monitors - These high-level radiation monitors are located adjacent to each main steam line as it exits Containment Redundant Monitors to Diagnose a SGTR

21 Control Room Indication of SGTR SG Tube Leak Display Air Evacuation PIG SG Blowdown Monitor N-16 Monitors Condenser WRGM is not one of the commonly used monitors for initial diagnosis of primary to secondary leakage

22 Failures necessary for WRGM to detect activity Beyond Design Basis Simulator Initial Conditions:

1) All 4 Safety Injection Tanks isolated to prevent automatic or manual injection
2) Main Steam Isolation Valve fails to close
3) High Pressure Safety Injection Pumps A and B failed to start in automatic - Manual start not allowed
4) Low Pressure Safety Injection Pumps A and B failed to start in automatic - Manual start not allowed
5) Motor Driven Emergency Feedwater Pumps A and B failed to start in automatic - Manual start not allowed
6) Steam Driven Emergency Feedwater Pump failed to start in automatic - Manual start not allowed
7) Worse Case Tube Rupture is 285 gpm due to double ended sheer of one (1) tube - Approximately ten (10) tubes were failed to create a rupture leakage rate greater than 3000 gpm

Emergency Planning Dean Burnett - Director, Fleet Emergency Planning 05

24 Issues Significance: Risk Significant Planning Standards Emergency Event Classification / Protective Action Recommendations Bounding event impacting Condenser WRGM is SGTR WRGM indications would not be reached with incorrect settings until more than six (6) hours after an event had been declared based on other instruments reaching their initiating condition thresholds Condenser WRGM no longer used for Emergency Plan Classification Dose Assessment There is no credible accident scenario that would result in the Condenser WRGM seeing activity levels reaching the SAE or GE thresholds The Condenser WRGM would not have been used as an input into the Dose Assessment process Dose Assessments based on available effluent pathways would have provided technically adequate estimates of releases of radioactive material to the environment

25 Emergency Planning - EAL Classification Beyond Design Basis Simulator Initial Conditions:

1) All 4 Safety Injection Tanks isolated to prevent automatic or manual injection
2) Main Steam Isolation Valve (MSIV) fails to close
3) High Pressure Safety Injection Pumps A and B failed to start in automatic - Manual start not allowed
4) Low Pressure Safety Injection Pumps A and B failed to start in automatic - Manual start not allowed
5) Motor Driven Emergency Feedwater Pumps A and B failed to start in automatic - Manual start not allowed
6) Steam Driven Emergency Feedwater Pump failed to start in automatic - Manual start not allowed
7) Worse Case Tube Rupture is 285 gpm due to double ended sheer of one (1) tube - Approximately ten (10) tubes were failed to create a rupture leakage rate greater than 3000 gpm

26 Emergency Planning - EAL Classification SAE and GE declared based on Fission Product Barrier EALs long before plant conditions degrade to cause cladding damage Beyond Design Basis Simulator Run Timeline

27 Emergency Planning - EAL Classification T0 (Event Start) - Alert conditions met - Potential loss of RCS or Fuel Clad T+ 0:55:58 - Site Area Emergency conditions met - Loss of RCS and Loss of Containment T+ 0:59:18 - General Emergency conditions met - Loss of 2 barriers and potential loss of 3rd T+ 6:58:12 - Core Exit Thermocouple (CET) reach 700° F This is the core condition that are the onset of heat induced fuel cladding damage*

  • At this point both the SAE and GE Classifications are made well before conditions are present for the onset of fuel failure which is at +6:58:12 (almost 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> after the GE would have been initially declared based upon event Classification using the Fission Product Barrier EALs).

The Condenser WRGM calibration issue WOULD NOT RESULT in an Over-Classification of either a SAE or GE Beyond Design Basis Simulator Run Timeline

28 Emergency Planning - Dose Assessment No impact to Dose Assessment Isolation of the affected SG ensures that adequate methods for assessing and monitoring actual or potential offsite consequences of a radiological emergency condition were available SGTR mitigating strategies include isolation of the Condenser WRGM from the affected SG resulting in the Condenser WRGM not being used for Dose Assessment The use of Dose Assessment using the output of the Condenser WRGM to determine emergency classifications or Protective Action Recommendations would not occur -- multiple system failures would have to occur for conditions to reach this level Dose Assessments based upon available effluent pathways would have provided technically adequate estimates of releases of radioactive material to the environment -- any Protective Action Recommendations resulting from Dose Assessments would have been accurate based on using the available effluent pathways Dose Projection Process capable of providing technically adequate estimates of radioactive material releases or projected offsite doses

Enforcement Perspective John Lewis - Regulatory Assurance Manager, Waterford 3 06

30 Enforcement Perspective No actual safety consequences No degraded Risk Significant Planning Standard function Condenser Wide Range Gas Monitor

Self Identified

Promptly corrected

Does not reflect current performance

31 Entergys Dose Assessment Process remained capable of providing technically adequate estimates of offsite doses By procedure, the affected Steam Generator would be isolated from the Main Condenser removing the Condenser WRGM from the flow path No adverse impact of the ability to classify a potential emergency condition associated with effluent releases - made accurately and in a timely manner No adverse impact on the capability to adequately estimate offsite releases Enforcement Perspective - Safety Significance

32 Enforcement Perspective - EAL Classification Due to alternate mitigating factors, accurate and timely declaration would be made - the Classification function was neither lost nor degraded Diverse or redundant Program Elements would allow for the Risk Significant Planning Standard (RSPS) function to be accomplished In alignment with the industry, the Condenser WRGM is no longer in EAL Classification Scheme because the exhaust is not normally radioactive

33 Enforcement Perspective - Dose Assessment Procedurally, the affected Steam Generator would be isolated from the Main Condenser, removing the Condenser WRGM from the flow path and not used for Dose Assessment Dose Assessments based on available effluent pathways would have provided technically adequate estimates of release of radioactive material to the environment, irrespective of the Condenser WRGM status Without the initiation of multiple additional failures beyond the Design Basis requirements, the Condenser WRGM would not see activity levels reaching the SAE or GE thresholds

34 Enforcement Perspective No impact to EAL Classifications and No impact to Dose Assessments No Potential Consequences to the Public No loss or degradation of RSPS Function Requirements of 10 CFR 50, Appendix E and 10 CFR 50.47(b) were met Very Low Safety Significance

Closing Comments John Ferrick - Site Vice President, Waterford 3 07

36 ML22224A246

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