ML22235A117
| ML22235A117 | |
| Person / Time | |
|---|---|
| Site: | National Bureau of Standards Reactor |
| Issue date: | 08/23/2022 |
| From: | Newton T US Dept of Commerce, National Institute of Standards & Technology (NIST) |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| Download: ML22235A117 (23) | |
Text
August 23, 2022 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 NISI
Subject:
Docket Number 50-184 Confirmatory Order
Dear Sirs/Madams:
I NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY U.S. DEPARTMENT OF COMMERCE Attached please find a draft of a proposed presentation on the February 3, 2021, NBSR event for NRC review. This is intended to be presented at the October meeting of the National Organization of Test, Research, and Training Reactors, and satisfies the requirement of the Confirmatory Order of August 1, 2022, section V. 7.d.
Deputy Director Chief, Reactor Operations and Engineering NIST Center for Neutron Research N,s1
The NCNR Fuel Failure Event: Recovery and Corrective Actions Tom Newton Deputy Director Chief of Reactor Operations and Engineering N** +4 Center for Neutron Research
2 NCNR
- One of three major neutron Science Centers in the US
- Supports > 3000 research participants annually
- Neutrons supplied by 20 MW reactor, the NBSR
- Reactor operates on a 38 day fuel cycle NCNR Instrument Layout BT9 MACSII BTT 3-AXIS 30mSANS VSANS NIOF
Cut-away View of the NBSR Core Top Grid Plate Fuel Elements (30)
Fuel Plates Liquid Hydrogen Cold Neutron Source Bottom Grid Plate D2O Primary Inlet Plenums Cd Shim Safety Arms (4)
Reactor Vessel Radial Beam Tubes (9)
Split Core:
18-cm Unfueled Gap - Flux Trap Primary Outlet (2)
Thermal Shield
Refueling January 4, 2021
- Routine refueling performed, with latching and latch checks
- After-the-event review showed these checks were done incorrectly.
- 2nd cycle element was not latched.
- Startup was delayed ~1 month because of COVID concerns.
- Routine (daily) starting and stopping of primary pumps pushed the element into an area outside of flow.
- Not detected by any instruments prior to startup.
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6 Video Surveillance of Core Began 2/23/21 Lower grid plate, near position J-7 Bottom of failed fuel element prior to removal from the core on August 5
February video surveillance showed single element out of position with apparent fuel damage.
Concluded that 450oC fuel safety limit had been exceeded, report to NRC in accordance with TS 6.6.1 Safety Limit 7
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tronReHeroh 6.6 Required Actions 6.6.1 Actions to Be Taken in the Event the Safety Limit is Exceeded (1) The reactor shall be shutdown and reactor operations shall not be resumed until authorized by the NRC.
(2) An immediate notification of the occurrence shall be made to the Chief, Reactor Operations and Engineering and the Chief, Reactor Operations.
The Chief, Reactor Operations and Engineering shall inform the NCNR director.
(3) Reports shall be made to the NRC in accordance with the specifications of Section 6.7.2. A written report shall include an analysis of the causes and extent of possible resultant damage, efficacy of corrective action, and recommendations for measures to prevent or reduce the probability of recurrence. The report shall be prepared by the Chief, Reactor Operations and Engineering and submitted to the SEC for review. The SEC shall review the report and submit it to the Director, NIST Center for Neutron Research director for approval. The Director shall then submit the report to the NRC.
Internal Technical Working Group (TWG) formed to investigate root cause May 13: TWG report complete; letter to NRC reporting inadequacies in:
Training and procedures in fuel latching Procedural compliance Management oversight June 3 follow-up: finding that element could inadvertently be unlatched by use of refueling tool without rotational force Initial Root Cause Investigation 2021 8
Page lof27 2 2 Root Cause Investigation of February 2021 Fuel Failure NCNR Technical Working Group April 30, 2021
SEC Subcommittee formed to investigate response, root cause review and corrective actions Two additional root causes:
Lack of change management program Culture of complacency 24 recommended corrective actions and program improvements Safety Evaluation Committee (SEC) Investigation 2021 9
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a FINAL Report SEC Subcommittee Report:
Review of the NCNR Event Response and Technical Working Group Root Cause Analysis and Corrective Action Plan Submitted to NCN R Director August 12, 2021 From the Safety E11aluation Committee (SEC) Subcommittee:
E11ent Response and Correcti11e Action Subcommittee Members:
Elizabeth Mackey, NIST Chief Safety officer, SEC Vice Chair Donald Pierce, NIST, NCNR Engineer, SEC Chair Amber Johnson, Uni11ersity of Maryland, SEC Member nmothy Bar11it.Skie, NIST, NCNR Health Physicist, SEC Member James Adams, NIST, Chief Radiation Physics Di11ision SEC SUbcommtttee RevieW 0
Change management:
New Aging Reactor Management program Organizational realignment, including additional training shift Procedure overhaul with compliance audits Problem Identification and Resolution System Review Team Review system changes Corrective Action Plan under development Integrated with other programs: trouble tickets, engineering changes, audits Tiered with safety significance Continuous improvement All NCNR-ROE staff involved in detailed corrective actions implementation and recovery tasks.
Annual benchmarking with other facilities Corrective Actions -- Management 10
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Plan of the day meeting Safety minute every day Weekly discussion of selected safety event, related to INPO 12-012, Traits of a Healthy Nuclear Safety Culture Reorganization of safety structure Safety Culture training for all personnel (ROE/HP)
Observation program - including all levels of NCNR management Employee Engagement - Safety recognition Safety culture changes 11 C
INPD INPO 12-012 December 2012 Traits of a Healthy Nuclear Safety Culture OPEN DISTRIBUTION Document
3rd party annual safety culture assessment 3rd party nuclear program assessment:
- 1. Problem Identification and Resolution
- 2. Event Root Cause
- 3. Training
- 4. Procedures
- 5. Safety Assessment Committee 6.
Safety Evaluation Committee independence and effective oversight Safety Culture Monitoring Panel Leadership Accountability Safety Evaluation Committee changes Safety culture training for leadership (INPO 12-012)
Management performance appraisal to include safety culture Safety culture corrective actions 12 e act*o s
Proficiency training Qualification for fuel movements Programs rewritten for better knowledge transfer Plan for more frequent staff attrition Development of standards for supervisors Qualification and oversight training Periodic management reviews of program Corrective Actions -- Training 13 C
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Personnel adherence Safety more integrated into procedures Revision to INPO 11-003 169 procedures were revised as condition for startup Rewrite fueling procedures Capture details Redundant rotation check New procedures Visual checks No contact with fuel head during and after visual check Corrective Actions -- Procedures 14 C
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New rotation check gauge New visual (video) checks Discontinue use of height checks NI noise gate Gurgen presentation Corrective Actions -- Equipment 15 C
2021 February 8: NRC Special Inspection Team begins February - May: Written reports on event, exceeding safety limit, and findings of inadequacies October 1: Root causes, planned corrective actions and request for permission to restart December 23: LAR submitted to require both rotation and visual latch checks in technical specifications 2022 March 16: SIT report issued; escalated enforcement; NCNR enters Alternate Dispute Resolution July 21: LAR approved August 1: NRC issues Confirmatory Order and Supplemental Inspection Plan NCNR interactions with NRC 16 C
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- 1. TS 2.1*: Safety limit violation (fuel cladding temperature exceeding 842 oF)
- 2. TS 3.1.3**: All grid positions not filled with full length elements
- 3. TS 6.4**: Procedure inadequacies - fuel handling
- 4. TS 6.4: Procedure inadequacies - startup monitoring for abnormal indications
- 5. TS 6.4: Procedure inadequacies - emergency response delays
- 6. TS 3.9.2.1**: elements not properly verified to be latched in the core grid.
- 7. Inadequate 50.59 review: changes to refueling tools
- 3/5/21 NCNR Report to NRC
- 5/13/21 NCNR Report to NRC NRC Findings 17 gs
Filter elements installed in all 30 core positions Each and all (4) primary pumps run Mechanical agitation: use of ultrasonics in low flow areas.
Chemical agitation: insertion of CO2 into pump discharge piping.
Analysis shows that major release of fission products from remaining debris is not credible.
Complete cleanup will require long term effort, including component replacement.
Primary Cleanup 18 Page 15 of 56 Section VI: Proee-ss: Room HS 4 and Gf>nenl BS Pr y I a (1.4.b 50U!Ce overlay imagufHS 3, HS 4, HS 7, H:S S, and ~1.11,ot spots)
Fall 2021: All fuel elements removed from core, including damaged element February 2022: Reactor vessel cleanup complete March 2022: Primary system cleanup using filter elements Most remaining fuel elements contained debris Startup core: Celikten presentation August 2022: Startup plan submitted to NRC Recovery timeline 19 Vessel cleanup February 2022 0 e y
Feb. 3, 2021 event was unprecedented in recent U.S. research reactor history.
NIST is committed to long term major corrective actions as outlined in the NRC Confirmatory Order.
Restart plan submitted to NRC outlining special startup preparations and precautions.
NRC Special Inspection ongoing.
Frequent and open communications with NRC is key to recovery and restart.
Conclusion 20 Co c us*
Backup slides 21
Latching video 22