ML030790347

NMC Presentation on Potential Common Mode Failure Auxiliary Feedwater

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 Committed to Nuclear Exce~llen~

Auxiliary Feedwater

, -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 i1 RESPONSE NMC---us Committed to NulearW"le 4

AFW SYSTEM DESIGN/RECIRC LINE ORIFICE DESIGN Tom Kendall NMC11*

Committed to NudearExcellen' 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" Committedto Nuclear Excellence 6

AFW System - Major Flow Paths SERVIC WATER MAIN

-FEED WATER

-CST

ROOT CAUSE EVALUATION STATUS Rich Flessner Committed to NuclearExcellencey 8

ROOT CAUSE TEAM Team Leader - Engineering Processes Member - Engineering Processes Team Team Member - AFW System Engineer Team Member - Design Engineer (KNPP)

NMme--Nc Committed to NucearEx'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 NuclearEnaellanea "

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 NuclearExceffence

RCE INVESTIGATION

• SE/SCR for MR 99-029*A-D recognized potential for SW plugging of RO I 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 NucteerExcellencel 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 NuellerExceffenIe 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 NudearF&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 NuclearEx cet"Ienc 19

-v

CLOSING COMMENTS Fred Cayia Commi*ted to NUcear Excellence 20