ML18318A064

Public Meeting Slides with Extra Content

ML18318A064
Person / Time
Site:	San Onofre
Issue date:	11/08/2018
From:	NRC Region 4
To:
References
Download: ML18318A064 (39)

Text

San Onofre Special Inspection Webinar November 8, 2018 NRC Region IV, Arlington, TX

Logistics

• Webinar Format

• Back-up Bridge Line (888) 469-1677, Passcode 2471451

• Questions and Answers 2

NRC Staff

• Eric Simpson, Special Inspection Team Leader Region IV Fuel Cycle and Decommissioning Branch

• Patricia Silva, Branch Chief Division of Spent Fuel Management

• Troy Pruett, Director Region IV Division of Nuclear Materials Safety 3

Webinar Agenda

• Background

• Canister Downloading Operations

• Inspection Team Findings

• Current Status

• Summary

• Questions & Answers 4

ISFSI Layout TN NUHOMS Design Holtec UMAX Design 5

Transnuclear NUHOMS 6

Holtec UMAX 7

Vertically Ventilated Module (Vault) 8

Spent Fuel Canister Holtec MPC Transfer Cask 9

Downloading: Shield Cone 10

Downloading: Transporter 11

Downloading: Vault Door 12

Downloading:

Alignment 13

Downloading:

Attaching Slings 14

Downloading:

Attaching Slings 15

Downloading Preparations 16

What Happened on August 3rd?

Low Dose Area Low Dose Area 17

What Happened on August 3rd?

18

What Happened on August 3rd?

19

What Happened on August 3rd?

20

What Happened on August 3rd?

21

Post Event Actions

• Spent Fuel Handling Activities Suspended

• NRC Inspection Activities

• San Onofre Notification to NRC

• Causal Evaluations

• Corrective Actions 22

Spent Fuel Handling Activities Suspended

• MPC 29 lowered into vault

• San Onofre suspends fuel loading

• MPC 30

- Inside Transfer Cask

- Seismically Restrained in Fuel Building 23

NRC Inspection Activities

• August 6th: NRC Region IV informally notified of Misalignment Event and initiates daily oversight communications

• August 7th: San Onofre commits to NRC review before resuming operations

• August 17th: NRC decides to conduct Special Inspection

• September 10-14: NRC Special Inspection Team onsite

• NRC to perform inspection prior to resumption of fuel loading 24

NRC Inspection Activities

• 2 Preliminary Escalated Findings

- Failure to provide redundant drop protection

- Failure to report

• 3 Preliminary Severity Level IV Violations

- Procedures

- Corrective actions

- Training

• Management Oversight Weaknesses 25

Causal Evaluations

• San Onofre Apparent Cause Evaluation

• Holtec Root Cause Analysis

• Common Cause Evaluation 26

Root Causes

• San Onofre Management failed to provide

- Adequate procedures

- Adequate training to support procedure

- Adequate oversight 27

Corrective Actions

• Training Requirements

• Procedure Enhancements

• Equipment Enhancements

• Oversight Improvements 28

Event Significance

• No Actual Drop of Canister

• No Radiological Release

• Load Drop Analysis (if canister fell) 29

Next Steps

• Issue NRC Inspection Report

• NRC Inspection of Causal Analyses

• NRC Inspection of Corrective Actions 30

Summary

• Could have been prevented

• Weaknesses in management oversight

• Multiple failed barriers

• Increased NRC oversight 31

Questions 32

Shims 33

Shims Original Design: Machined Slots Design Change: Standoffs Pins 34

Radiation Levels on the ISFSI Pad Survey Results found by the NRC:

Lids: 0.015 - 0.018 mR/hr Outlet Vents: 0.12 - 0.24 mR/hr Closure Lid Canister #29 levels in Gamma Lid: 0.015 mR/hr TS limit on Lid = 0.4 mR/hr Outlet Vent: 0.12 mR/hr TS limit on Outlet Vent = 1.8 mR/hr 35

Aging Management Plan

• Required upon license renewal

• Tracks Degradation of Structures, Systems, and Components

- Concrete

- Steel

- Stainless Steel

• Some licensees have performed Aging Management Inspections

- No breaches of the canisters have been identified

- No chloride induced stress corrosion cracking has been identified

• California Costal Commission Commitment 36

Canister Drop analysis

• San Onofre provided preliminary analysis

• Analysis under NRC review

• San Onofre preliminary results: no loss of containment 37

Unresolved Item

• Last NRC Inspection report (2017-001) documented an Unresolved Item

• Licensee has modified loading operations to address NRC concern 38

Seismic and Flooding

• Both ISFSI systems at San Onofre are evaluated for:

- Design Base Earthquake

- Maximum flood height and flood velocity (Tsunami) 39