ML21096A183
| ML21096A183 | |
| Person / Time | |
|---|---|
| Issue date: | 04/08/2021 |
| From: | Chang Y, Michelle Kichline, Jing Xing NRC/RES/DRA/HFRB |
| To: | |
| Xing, Jang - 301 415 2410 | |
| Shared Package | |
| ML21096A176 | List: |
| References | |
| Download: ML21096A183 (7) | |
Text
IDHEAS dependency model and guidance (IDHEAS-DEP)
Jing Xing, Michelle Kichline, Y. James Chang,,
U.S. Nuclear Regulatory Commission Presented by Jing Xing to the public meeting on IDHEAS April-08-2021
Overview
- 1. IDHEAS Dependency Model
- 4. Path forward with IDHEAS dependency 2
IDHEAS-G Dependency Model Identify the dependency context (HFE1, HFE2)
- Consequential dependency in an event sequence
- Resource-sharing dependency
- Cognitive dependency HFE1 and HFE2 are Model the dependency context HFE2lHFE1 independent All no Any Are there changes to HFE2s:
Definition? Time required and time available?
P(HFE1,HFE2)= yes?
Feasibility? Additional CFMs?
P(HFE1)*P(HFE2) Critical tasks? PIF attributes?
Yes Calculate P(HFE2lHFE1) based on P(HFE1,HFE2) =
context changes to HFE2 and using P(HFE1)*P(HFE2lHFE1) same method as individual HFEs HFE2lHFE1 means the occurrence of event HFE2 given the occurrence of event HFE1, where HFE1 is the first event and HFE2 is the second event. 3
NRC HRA Dependency Workgroup (Nov. 2020 - March 2021)
Purpose:
Understand HRA dependency and develop guidance for using IDHEAS Dependency Model
- Activities:
- Phase 1: Six analysts each performed dependency analysis of an example event (from SDP or PRA models) using IDHEAS-ECA and IDHEAS Dependency Model
- Phase 2: The project team developed the draft guidance and the analysts piloted it with the examples
- Phase 3: The workgroup will review and comment on the fully written guidance
- Workgroup members:
- A. Brown, C. Hunter, J. DeJesus, M. Pohida, and K. Tetter, Reliability And Risk Analysts, NRR and RES
- A. Rosebrook, Sr. Reactor Analyst, Region II
- K. Gunter, Lead Engineer, Jensen Hughes Company
- M. Presley, Principal Technical Leader, EPRI 4
IDHEAS dependency guidance framework HFE2HFE1 Pre-determination:
Assess the relationships between Entry conditions No STOP met?
the HFEs for no dependency, complete dependency, or further Yes No dependency analysis Step 1 Pre-determination Complete Screening analysis:
dependency Assessing screening dependent HEPs without using IDHEAS-ECA (for HRA applications where detailed information is not Step 2 Step 3 available or the individual HEPs of Screening analysis Detailed analysis the HFEs were not from IDHEAS-ECA)
Graded screening IDHEAS-ECA calculated Detailed analysis: dependent HEP dependent HEP Analyze dependency factors and their impact on HEPs using IDEHAS-ECA
Preliminary insights on IDHEAS dependency guidance
- IDHEAS dependency analysis is based on IDHEAS-G and IDHEAS-DATA
- THERP dependency: Each relationship deems a multiplier
- IDHEAS dependency: The context of each relationship is analyzed for its impact on the dependent HEP
- The assessed dependency is explainable on why the dependency occurs and how it impacts HEPs
- Enhanced HRA traceability and documentation
- Explicit identification of dependency mechanisms for reducing dependency
- Preliminary piloting of the draft dependency guidance dependency shows promise
- that the dependent HEPs calculated from IDHEAS dependency model were more consistent with analysts assessment, not overly conservative 6
Path forward with IDHEAS dependency
- IDHEAS Dependency Model in IDHEAS-G report (NUREG-2198)
Appendix K, in publication, 2021
- Publish The guidance for using IDHEAS Dependency Model (IDHEAS-DEP) as a NRC Research Information Letter and collect public comments
- summer 2021
- Document and publish the dependency analysis examples from the NRC Dependency Workgroup - summer 2021
- Update IDHEAS-ECA report and software tool by incorporating IDHEAS dependency guidance - winter 2021 7