ML21069A020
| ML21069A020 | |
| Person / Time | |
|---|---|
| Issue date: | 03/03/2021 |
| From: | Wendy Reed, Vanwert C Office of Nuclear Regulatory Research |
| To: | |
| W. Reed | |
| References | |
| Download: ML21069A020 (14) | |
Text
Phenomena Identification and Ranking Tables:
US NRC Perspective Chris Van Wert and Wendy Reed US Nuclear Regulatory Commission Presentation to the MSR PIRT Workshop on Licensing Basis Events March 3, 2021
One Objective, Separate Roles Common Objective: Enable Safe Use Industry Role: Make safety case Regulator Role: Ensure Regulatory Compliance 2
PIRT process is part of ensuring safety Common Objective: Enable Safe Use Ensure all issues critical to safety are identified Identify areas for additional research or heightened review Experiments, modeling and analysis Phenomena Identification and Ranking Table 3
4 Principle/General Design Criteria Regulations Regulatory Guidance PIRTs help identify:
Novel issues not covered by the current regulatory infrastructure.
Confirmatory tool needs Standard Review Plan What will NRC do with PIRT results?
GDC X GDC Y GDC Z Reg A
Reg B
Reg C
Reg D
R G
1 R
G 2
G 5
R G
6 S
R P
a S
R P
d S
R P
c S
R P
d S
R P
b S
R P
c S
R P
d
5 LMP introduces the concept of Failure-Consequence Curves into NRC advanced reactor reviews.
PIRTs and the Licensing Modernization Project (LMP)
6 PIRTs and the Licensing Modernization Project (LMP)
- F-C curves are used to determine event categorization and application content
- PIRTs can be used to help identify areas that the reviewer needs to focus on to make sure that all applicable event sequences are included in the application
- PIRTs can also be used to identify areas where additional regulatory guidance needs to be provided or independent confirmatory tools should be updated or developed.
ATF PIRT Development development of technical bases old paradigm development of regulatory infrastructure licensing activities schedule efficiency enabled by plan ATF project plan phenomena identification and ranking exercise PIRT maintenance refinement of regulatory infrastructure licensing activities 7
8 https://www.nrc.gov/reactors/atf/related-docs.html#pirt
Driver: identify the simulation tools that will be used for confirmatory safety analysis Objective: understand modeling needs of simulation tools Outcomes: identified modeling and simulation needs in neutronics and thermal-hydraulic analysis.
9 ADAMS Accession No.: ML18124A330
- Facilitator is Key - Responsible for planning and facilitating discussions, documenting the identification and ranking outcomes of the panel
- Member experience & credentials drive results -
Members should be actively involved in experimental and analytical work on the subject.
- Documentation creates long-lasting value -
Documenting rationale for rankings allows others to understand & effectively use PIRT results. Allows readers to build on foundation of the PIRT.
Lessons Learned What makes a PIRT successful? - NRC Staff Perspective 10 ML18057A212
Additional Information 11
Recent Example: High Burnup Fuel Driver
- In mid 1990s, research started to indicate that certain regulatory criteria might not be adequate at high burnups and may not be effective for the new cladding alloys
- New, focused research was needed to ensure that reactor safety was maintained
- A PIRT was conducted to inform research planning 12
Recent Example: High Burnup Fuel Approach
- Conducted 3 PIRTS, defined by hardware and scenario Rod Ejection Accidents in Pressurized Water Reactors Containing High Burnup Fuel
- Power Oscillations Without Scram in Boiling Water Reactors Containing High Burnup Fuel
- Loss-of-Coolant Accidents in Pressurized and Boiling Water Reactors Containing High Burnup Fuel
- Considered 4 categories: plant transient analysis, integral testing, transient fuel rod analysis, separate effects testing 13
Recent Example: High Burnup Fuel Outcome Three reports document the results of this expert elicitation.
- Phenomenon Identification and Ranking Tables (PIRTs) for Rod Ejection Accidents in Pressurized Water Reactors Containing High Burnup Fuel (NUREG/CR-6742)
- Phenomenon Identification and Ranking Tables (PIRTs) for Power Oscillations Without Scram in Boiling Water Reactors Containing High Burnup Fuel (NUREG/CR-6743)
- Phenomenon Identification and Ranking Tables (PIRTs) for Loss-of-Coolant Accidents in Pressurized and Boiling Water Reactors Containing High Burnup Fuel (NUREG/CR-6744)
PIRT reports did not include conclusions, by design. Implications of the phenomenon rankings are discussed in the staff report, and methods of resolving issues related to fuel damage limits are outlined.
- Implications from the Phenomenon Identification and Ranking Tables (PIRTs) and Suggested Research Activities for High Burnup Fuel (NUREG-1749) 14