ML21098A146
| ML21098A146 | |
| Person / Time | |
|---|---|
| Issue date: | 04/06/2021 |
| From: | Js Hyslop NRC/NRR/DRA/APLB |
| To: | |
| Kenneth Hamburger | |
| Shared Package | |
| ML21098A144 | List: |
| References | |
| Download: ML21098A146 (10) | |
Text
Industry Participation to Support Resolution of pre-GI 018 (Aluminum HEAF)
NRR/Division of Risk Assessment RES/Division of Risk Analysis Dr. J.S. Hyslop, NRR/DRA/APLB, presenting
HEAF Pre-Generic Issue Update - April 6th, 2021 Overview
- Industry engagement
- Benefits from industry participation in the technical evaluation
- Drawbacks from technical evaluation performed by staff
- Some details of the technical evaluation
- Preliminary factors developed by staff to prioritize pilot plants
- Final remarks 2
HEAF Pre-Generic Issue Update - April 6th, 2021 Industry Engagement in GI Continued industry participation is requested and strongly desired Collaborate to perform technical evaluation necessary for GI
- Full industry participation is ideal
- Pilot plants probably more practical Technical evaluation needed for plants with fire PRAs, and for those plants without PRAs whose licensing basis is deterministic
- Viable pilot plants needed to cover both cases of technical evaluation
- Staff aware from risk analyses performed by EPRI that many plants having a fire PRA will not pose a significant risk increase Mutual benefits for industry and the NRC from continued collaboration 3
HEAF Pre-Generic Issue Update - April 6th, 2021 Benefits of Industry Participation Industry fire PRA models are more refined and representative - lead to better estimates of risk increase
- Greater satisfaction by both NRC and industry with respect to results Timely resolution of issue
- Pilots much better positioned to gather detailed information about their plant
- Resources to perform assessments distributed within industry Pilots can play a role in identifying measures to mitigate HEAF should Al HEAF be significant, and corresponding credit e.g.
- Additional mitigation features not credited in the PRA
- Potential plant improvements With respect to timeliness, remaining plants in the fleet with significant exposure to Al HEAF will know sooner and be able to take measures sooner 4
HEAF Pre-Generic Issue Update - April 6th, 2021 Drawbacks of Analysis Performed by Staff
- Likely analysis will be more conservative
- Industry collaboration needed regardless
- Staff will still need to engage industry to collect information, e.g.
- Spatial information,
- Cable raceway database information,
- Information to update NRC SPAR models, etc.
- Staff will identify measures to address Al HEAF should issue be important, and will establish the credit for these measures 5
HEAF Pre-Generic Issue Update - April 6th, 2021 Details of Industry Participation for Plants with a Fire PRA
- Assessment phase
- Industry will evaluate the risk increase from Al HEAF over existing HEAF treatment with NRC/EPRI MOU model
- If progress to Regulatory Office Implementation (ROI) phase
- Industry will support evaluation of existing measures or improvements to address Al HEAF 6
HEAF Pre-Generic Issue Update - April 6th, 2021 Industry Participation For Plants With No FPRA; With a Deterministic Licensing Basis
- Assessment phase
- Industry will assess whether protected train per deterministic licensing basis is damaged by the Al HEAF
- Assessment for deterministic licensing basis does not evaluate the difference between Al HEAF and the existing HEAF model
- Deterministic licensing basis does not appear to consider HEAF
- If progress to ROI phase
- Industry will assist in the evaluation of improvements to prevent damage to protected train 7
HEAF Pre-Generic Issue Update - April 6th, 2021 Determining Viable Pilots for GI Process Industry encouraged to work with staff to identify viable pilots Preliminary factors developed by staff to prioritize pilots
- Plants without a main generator circuit breaker
- Plants having direct generator feed for 1E switchgear
- Plants which potentially expose redundant train to Al HEAF Plants which expose redundant train for prioritization
- Fire PRA: redundant and diverse trains in same physical analysis unit
- No fire PRA: expose protected train or defeat spatial separation credited in fire protection program
- Applicable only for locations containing equipment subject to a HEAF
- Rooms containing Medium Voltage switchgear,
- Rooms containing Low Voltage switchgear,
- Other locations containing bus ducts or HEAF susceptible equipment > 440V 8
HEAF Pre-Generic Issue Update - April 6th, 2021 Determining Viable Pilots for GI Process (cont.)
- More detailed spatial information will determine importance to Al HEAF
- Fire PRA significance varies according to spatial relationship of Al HEAF source to important fire PRA targets providing redundant and diverse mitigative capability
- Plant with significant risk contribution from HEAF with current model may not exhibit significant risk increase from Al 9
HEAF Pre-Generic Issue Update - April 6th, 2021 Final Remarks
- Pilot plants participation in resolving pre-GI is of mutual benefit to NRC and the industry
- Timeliness of resolution supported by industry participation is important to NRC and the industry
- Staff believes that industry participation will lead to a mutually satisfactory resolution 10