ML18318A064
| 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 5
TN NUHOMS Design Holtec UMAX Design
Transnuclear NUHOMS 6
Holtec UMAX 7
Vertically Ventilated Module (Vault) 8
Spent Fuel Canister 9
Holtec MPC Transfer Cask
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
17 What Happened on August 3rd?
Low Dose Area Low Dose Area
What Happened on August 3rd?
18
What Happened on August 3rd?
19
What Happened on August 3rd?
20
21 What Happened on August 3rd?
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 23
- MPC 29 lowered into vault
- San Onofre suspends fuel loading
- MPC 30
- Inside Transfer Cask
- Seismically Restrained in Fuel Building
NRC Inspection Activities 24
- 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
NRC Inspection Activities 25
- 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
Causal Evaluations 26
- San Onofre Apparent Cause Evaluation
- Holtec Root Cause Analysis
- Common Cause Evaluation
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 Design Change: Standoffs Pins Original Design: Machined Slots 34
35 Radiation Levels on the ISFSI Pad TS limit on Lid = 0.4 mR/hr TS limit on Outlet Vent = 1.8 mR/hr Canister #29 levels in Gamma Lid: 0.015 mR/hr Outlet Vent: 0.12 mR/hr Lids: 0.015 - 0.018 mR/hr Outlet Vents: 0.12 - 0.24 mR/hr Survey Results found by the NRC:
Closure Lid
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