ML030790347
| ML030790347 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 10/31/2002 |
| From: | Nuclear Management Co |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| FOIA/PA-2003-0094 | |
| Download: ML030790347 (20) | |
Text
Point Beach Nuclear Plantj¶ Potential Common Mode Failure NMCi-"b Auxiliary Feedwater Committed to Nuclear Exce~llen~
-7ib 3-2 0 0 2s
INTRODUCTION Fred Cayia NMCi Committed to NudeM:
- lEncele, 2
AGENDA
"* Introduction (Fred Cayia)
"* Response (Ken Peveler)
"= System Design/Orifice Design (Tom Kendall)
"* Root Cause Status (Rich Flessner)
"* Immediate Corrective Actions (Duane Schoon)
"* On-Line Risk Assessment (Jim Masterlark)
"* Incident Investigation (Stu Thomas)
"* Closing Comments (Fred Cayia)
Committed to NuceerExcette
,Y 3
ORGANIZATIONAL
RESPONSE
NMC---us Committed to Nulear W"le i1 4
AFW SYSTEM DESIGN/RECIRC LINE ORIFICE DESIGN Tom Kendall NMC11*
Committed to Nudear Excellen' 5
AFW DESIGN BASIS
> Supply water to SG to remove decay heat and replenish SG inventory
> Safety-Related Functions:
"* Supply FW during accidents with main steam safety valve opening
"* Supply FW during accidents which require rapid RCS cooldown
"* Isolation capability NMC" Committed to Nuclear Excellence 6
AFW System - Major Flow Paths SERVIC WATER MAIN
-FEED WATER
-CST
ROOT CAUSE EVALUATION STATUS Rich Flessner Committed to Nuclear Excellencey 8
ROOT CAUSE TEAM Team Team Team Team Leader - Engineering Processes Member - Engineering Processes Member - AFW System Engineer Member - Design Engineer (KNPP)
NMme--Nc Committed to Nucear Ex'cellnc 9
/
ROOT CAUSE CHARTER
> Determine the following:
"* Timeline of key events
"* The root and contributing causes of why the condition exists, including any potential human performance issues
"* Why the problem was not identified previously NMmedC-Committed to Nuclear Enaellanea 10
ROOT CAUSE CHARTER
> Make recommendations for:
"* Correcting the problem, including any remedial actions
"* Preventing recurrence of the problem
"* Applicability of the root cause to other areas (extent of condition), including verification that a safety-related AFW recirculation flow path exists for the postulated failure modes NMC--d Committed to Nuclear Exceffence
RCE INVESTIGATION
I
- Plugging not considered a concern because recirc flow not required
- 3 AFW pump recirc lines modified with new design RO prior to decision to upgrade recirc line to have a safety-function to provide flow to CST
- 1 AFW pump recirc line modified after recirc line safety function was changed NMCittd t
Commiffed to Nucteer Excellencel 12
IMMEDIATE lo CORRECTIVE ACTIONS
);Immediate Actions
"* Information tags placed
"* Shifts briefed and trained on issue
"* Procedure changes
"* Notification made to NRC
"* Root Cause Evaluation initiated 9 Multi-discipline RCE Team NMC Commlffed to Nud kefer E
cele 13
ON-LINE RISK ASSESSMENT Jim Masterlark NMC--dt Committed to Nueller ExceffenIe 14
On-Line Risk Monitoring Plant is currently at an elevated risk level due to additional Operator Actions.
NMce Committd to Nucla xel*dl 15
On-Line Risk Monitoring Continued SPerformed a Bounding Risk Evaluation
"* Large Uncertainty in Failure Probabilities
"* Bound Risk to ensure that we do not underestimate risk associated with both planned and unplanned configurations
"* Performed Simulator Runs and Operator/Training Interviews to assist with evaluation of Human Error Probabilities NMc*
Committed to Nudear F&cellerwe1 19" 16
On-Line Risk Monitoring Continued
> Analysis Provides an Upper Bound for Risk
"* Assumes high probability for plugging orifice if Service Water is used
"* Does not account for water treatment for CST make-up. This would reduce probability for need to use raw Service Water for some transients/accidents.
Committed to Nudear Excellence 17
On-Line Risk Monitoring ar Current Risk
> Current Risk Level is Yellow (safety monitor)
> Monitoring Planned plant activities to evaluate impact on risk
> Will receive appropriate approvals and.take appropriate compensatory measures as needed.
> Risk model currently credits temporary information tags. Model will be updated as procedure changes are implemented.
> Expect risk to be near Green/Yellow threshold after all procedure changes are complete.
NMCefl"1 Comm/*ed to Nudeor "Excefltenc 1
INCIDENT INVESTIGATION
"* Investigation of the l*fe*hQM post maintenance testing of P38A continues.
"* Based on initial discussions and written statements of both operators and maintenance personnel, maintenance and testing activities were performed in accordance with procedures.
Committed to Nuclear Ex cet"Ienc 19
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CLOSING COMMENTS Fred Cayia Commi*ted to NUcear Excellence 20