ML25084A359
| ML25084A359 | |
| Person / Time | |
|---|---|
| Issue date: | 03/13/2025 |
| From: | Brian Wagner NRC/NMSS/DFM/NARAB |
| To: | |
| References | |
| Download: ML25084A359 (14) | |
Text
NRC REVIEW OF A RISK-INFORMED METHODOLOGY FOR A TRANSPORTABLE MICROREACTOR PACKAGE Brian Wagner, Reliability and Risk Analyst Division of Fuel Management Office of Nuclear Material Safety and Safeguards U.S. Nuclear Regulatory Commission 2
Overview 3
- The certification process provides the infrastructure for regulating transportation package designs.
- A risk-informed methodology can be used as the basis for an exemption request under 10 CFR 71.12, with appropriate justifications.
- The NRC endorsed a methodology, developed by Pacific Northwest National Laboratory (PNNL), for the Project Pele transportable microreactor in SECY-24-0062 (ML23320A124).
- The staff is considering approaches for licensing transportation of new fuels.
Focus of Risk Method Supporting Project Pele Transportation 4
Certification of Transportation Packages 5
- 1. Preapplication Meetings
- 2. Application Submittal
- 4. Safety and Security Review
- 5. Issuance of Final Safety Evaluation and Certificate of Compliance (Up to 5 years)
If the application is accepted If all pertinent regulations are satisfied
Package Performance Tests and Conditions 6
- Normal conditions of transport (10 CFR 71.71)
- Hot and cold temperatures
- Reduced and increased external pressure
- Vibration
- Water spray
- Free drop (1 to 4 feet)
- Corner drop
- Compression test
- Penetration test
- Hypothetical accident conditions (10 CFR 71.73) foot drop test inch puncture test minute fire at 1,475 degrees Fahrenheit
- Water immersion test (fissile/nonfissile)
Project Pele 7
- Goal: Design and fabricate a transportable microreactor
- Producing less than 5 megawatts
- Operable for 3+ years
- Reactor module fits into a single custom-developed International Organization for Standardization container which resembles a CONtainer EXpress (CONEX) box
Why a Risk Methodology?
8
- Hypothetical accident conditions (10 CFR 71.73)
- 30-foot drop test
- 40-inch puncture test
- 30-minute fire at 1,475 degrees Fahrenheit
- Water immersion test (fissile/nonfissile)
- Additional requirements for Type B packages
- Containment criteria for normal form material (10 CFR 71.51(a)(1) and (2))
- Dose rates after hypothetical accident conditions (10 CFR 71.51(a)(2))
- Regulatory approval pathways
- Alternative test criteria in 10 CFR 71.41(c)
- Exemptions (10 CFR 71.12) from specific requirements using a risk-informed approach
A Risk-Informed Methodology 9
- The risk-informed methodology consists of (1) risk evaluation guidelines and (2) a systematic process to develop a probabilistic risk assessment.
- Risk evaluation guidelines:
- Frequency-consequence (F-C) plots used as surrogate guidelines for acceptable levels of risk of bounding representative accidents
- Informed by existing NRC performance criteria for nuclear fuel facilities, U.S.
Department of Energy nuclear facilities, and International Atomic Energy Agency risk evaluation guidelines
- Consistent with similar risk-informed, performance-based approaches endorsed by the NRC, such as described in Regulatory Guide 1.233
A Risk-Informed Methodology 10 Probabilistic risk assessment to identify and evaluate bounding representative accidents Goals to (1) inform the package design regarding the risk significance of containment and shielding features and (2) identify the need for compensatory measures during transportation Elements of the probabilistic risk assessment
- Identification of safety functions
- Characterization of hazardous conditions to identify accidents
- Determination of accident likelihoods
- Consequence analysis
- Evaluation of probabilistic risk assessment results against risk evaluation guidelines
- Sensitivity studies
- Uncertainty analysis
- Defense in depth
Proposed Risk Evaluation Guidelines for the Public and Workers 11
Looking Forward: Potential Regulatory Needs for New Fuels 12
Conclusion 13
- The NRC is committed to the safe, secure, and efficient transportation of radioactive materials.
- A risk-informed methodology can provide the necessary justification for approving exemptions for transportable nuclear power plants for domestic use.
- Transport regulations in 10 CFR Part 71 are adequate to approve transportation package designs for new fuels and microreactors, but the NRC is open to risk-informed approaches.
References 14 SECY-24-0062: https://www.nrc.gov/docs/ML2332/ML23320A124.html Letter of Approval: https://www.nrc.gov/docs/ML2332/ML23321A131.html Final Endorsement Letter: https://www.nrc.gov/docs/ML2427/ML24271A054.pdf Final PNNL Report: https://www.nrc.gov/docs/ML2426/ML24268A100.html NEI 18-04: https://www.nrc.gov/docs/ML1924/ML19241A472.pdf Regulatory Guide 1.233: https://www.nrc.gov/docs/ml2009/ml20091l698.pdf