ML16312A507
| ML16312A507 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 11/09/2016 |
| From: | Xcel Energy Inc |
| To: | Office of Nuclear Material Safety and Safeguards |
| Jacobs C, 301-415-6825 | |
| Shared Package | |
| ML16312A513 | List: |
| References | |
| CAC L25156 | |
| Download: ML16312A507 (25) | |
Text
Project Plan for Restoring Dry Shielded Canister (DSC) 11 - 16 Compliance to 10 CFR Part 72 Pre-Submittal Meeting Monticello Nuclear Generating Plant Independent Spent Fuel Storage Installation (ISFSI)
Xcel Energy November 9, 2016 1
Introduction 2
Xcel Energy Pat Burke - Vice President Engineering and Technical Services Jeff Place - Nuclear Vice President Fleet Operations Kent Scott - Director Site Operations, MNGP Marty Murphy - Director, Nuclear Licensing, Regulatory Affairs Scott Marty - Director, Dry Fuel Storage Mike Baumann - Director, Nuclear Fuels Glenn Adams - Project Licensing
Introduction 3
Meeting Objectives Understand Project Plan for restoring DSC 11 - 16 compliance
DSC 16 is currently restored Understand Project Schedule Understand NRC engagement and approvals
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Background===
4 2013 DSC 11 - 16 Loading Campaign
Dye penetrant (PT) exams non-compliant with Technical Specification (TS) 1.2.5
Integrity of welds assured through weld process, advantages of multi-layer weld, visual inspection, and helium leak testing
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Background===
5 DSC 16 Exemption (6/15/2016) - Reasonable Assurance Integrity of fuel cladding Quality of the welding process Advantages of multi-layer weld technique Visual inspections of welds Helium leak testing Lack of failure mechanisms Margin of safety available in welds demonstrated by:
Analysis of theoretical full circumferential flaws
Analysis of flaw distribution derived from DSC 16 PAUT exams
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Background===
6 Confirmatory Order EA-14-193 (12/21/2015)
- 1. Restore DSC 11 - 16 compliance to 10 CFR 72 within 5 years of exemption (i.e., by 6/15/2021)
DSC 16 restored by Exemption 6/15/2016; placed in HSM 10/5/2016
- 2. Submit Project Plan for restoring compliance by 12/12/2016 Scope of Project Plan is DSC 11 - 15
Project Principles 7
Maximize Nuclear Safety Minimize Industrial Safety Risks Minimize Radiological Dose Using proven technology Timely restoration to compliance Optimize submittal scope
Alternatives 8
PAUT Scope Considered DSC 16 DSC 11 and DSC 16 DSC 11 - 16 PAUT Methods Considered In Horizontal Storage Module (HSM)
In Transfer Cask with Inspection Ring In Transfer Cask - Horizontal on Trailer In Transfer Cask - Vertical on Refuel Floor PAUT Timing Considered Perform in 2017 Perform in 2018
Alternatives - Scope 9
PAUT of DSC 16 - Results Applied to DSCs 11 - 15 Demonstrate DSC 16 is a representative sample. Margins of safety account for potential differences between DSC 16 and DSCs 11 - 15 Benefit Eliminate nuclear risk associated with handling Eliminate industrial risk and radiological impact of handling and PAUT Challenges Uncertainty of potential flaws in DSCs 11 - 15
Alternatives - Scope 10 PAUT of DSC 11 and 16 - Results Applied to DSCs 12 - 15 Perform PAUT on DSC 11. Demonstrate DSCs 11 and 16 are representative samples. Margins of safety account for potential differences between DSC 11 and 16, and DSCs 12 - 15 Benefits Specific analysis of DSC 11 PAUT results Improved confidence in weld quality of DSCs 12 - 15 Minimize nuclear risk associated with handling Minimize industrial risk and radiological impact of handling and PAUT Challenges Uncertainty of potential flaws in DSC 12 - 15 Increased nuclear risk associated with handling
Alternatives - Scope 11 PAUT of DSC 11 - 16 Perform PAUT on DSC 11 - 16 Benefit Specific analysis of DSC 11 - 16 PAUT results Challenges Increased nuclear risk associated with handling Increased industrial risk and radiological impact of handling and PAUT
Alternatives - Methods 12 PAUT in HSM Benefits DSC is not moved Potential lower occupational dose Incorporates same PAUT transducers Challenges
< 360o coverage due to rails 72.48 screening implications Unproven transducer delivery tooling Unproven shielding design Weather risks
Alternatives - Methods 13 PAUT in TC with Inspection Ring Benefits Minimize DSC movement and transfer Same weld coverage as DSC 16 Potential lower occupational dose Incorporates same PAUT transducers Challenges Requires move of DSC into TC 72.48 screening implications Unproven transducer delivery tooling Unproven shielding design Unproven transfer system modifications Weather risks
Alternatives - Methods 14 PAUT in TC - Horizontal on Trailer Benefits Minimize DSC movement and transfer Same weld coverage as DSC 16 Incorporates same PAUT transducers Challenges Requires move of DSC into TC 72.48 screening implications Higher occupational dose Unproven transducer delivery tooling Weather risks
Alternatives - Methods 15 PAUT in TC - Vertical on Refuel Floor Benefits Same weld coverage as DSC 16 Proven 72.48 determination on refueling floor Proven transducer delivery tooling Proven PAUT transducers Controlled environment Challenges Requires move of DSC into TC Requires move to Refuel Floor Known occupational radiological dose (~ 1 Rem / DSC)
Alternatives - PAUT Timing Considerations 16 Perform in 2017 Challenges Less time to resolve open question on moving non-compliant DSC(s)
Requires a dedicated crew mobilization Perform in 2018 Benefits Allows time to resolve the open questions Allows execution with a crew mobilized for 2018 campaign
Selected Approach 17 PAUT of DSC 11 and 16 Optimized balance of nuclear, radiological and industrial safety Improved confidence in weld quality of DSCs 11 - 15 PAUT in Transfer Cask on Refueling Floor Same weld coverage as DSC 16 Proven 72.48 determination on refueling floor Proven transducer delivery tooling Proven PAUT transducers Controlled environment mitigates weather and environmental risks PAUT in 2018 (following planned 2018 DSC loading campaign)
Allows time for resolution of open questions Allows execution with crew mobilized for 2018 campaign Provides margin to Confirmatory Order deadline
Project Plan 18 The project plan consists of two major areas:
1.
Open questions on movement of non-compliant DSCs Move non-compliant DSC from HSM Move non-compliant DSC to HSM 2.
Exemption to Restore Compliance Exempt DSCs 11 - 15 from TS 1.2.5 using DSC 11 and DSC 16 PAUT directly applied to DSC 11, and as representative of DSCs 12 - 15
Project Plan 19 Open Question on Movement of Non-Compliant DSC Certificate of Compliance 1004 and TS have no action statements for discovery of noncompliant PT discovered during Storage TS 1.2.5 Action for unacceptable weld requires weld repair and re-performance of PT TS 1.2.10 Limit and Applicability requires that any TC/DSC dropped on route to, or at, the storage pad, the fuel shall be returned to the spent fuel pool and the DSC removed from service and evaluated
Project Plan 20 Bases for Movement of non-compliant DSC from HSM Reasonable Assurance of Safety, Presumption of Operability Integrity of fuel cladding Quality of the welding process Advantages of multi-layer weld technique Visual inspections of welds Helium leak testing Lack of failure mechanisms Margin of safety available in welds demonstrated by:
Analysis of theoretical full circumferential flaws
Analysis of flaw distribution derived from PAUT exams
Project Plan 21 Bases for movement of non-compliant DSC to HSM Additional assurances supporting return to HSM Compliant PT exam of OTCP final pass Comparative review of PAUT data informed by analysis of theoretical flaw and flaw distribution derived from DSC 16 PAUT
Project Plan 22 Exemption Request of DSCs 11 - 15 Bases:
Integrity of fuel cladding Quality of the welding process Advantages of multi-layer weld technique Visual inspections of welds Helium leak testing Lack of failure mechanisms DSC 11 and DSC 16 are representative (first and last)
Margin of safety available in welds demonstrated by:
Analysis of theoretical full circumferential flaws
Analysis of flaw distribution derived from DSC 11 and 16 PAUT exams
Project Plan 23 Milestones:
12/2016 Submit Project Plan 01/2017 NRC input on open questions on movement of DSCs 03/2017 Clarify open questions on movement of DSCs 08/2017 Resolve open question on movement of DSCs 08/2018 Transfer DSC 11 from HSM to Refuel Floor
Perform PT and PAUT
Perform OTCP PT and comparative review of PAUT data
Return DSC 11 to HSM
Perform analysis and prepare exemption request 12/2018 Submit exemption request 12/2019 NRC grant exemption request
Project Plan 24 Plan Content Cover letter High level summary and milestone schedule Progress Reporting Required 180 days after project plan submittal, and every 360 days thereafter Will provide additional updates as appropriate as development and planning progress
Summary 25 Work with NRC to resolve open question on movement of non-compliant DSCs from HSM Work with NRC to resolve open question on movement of non-compliant DSCs to HSM Plan is to submit an exemption request for DSCs 11 - 15 from TS 1.2.5 based on PAUT and analysis of DSC 11 and DSC 16 and demonstrating these are representative of DSCs 12 - 15