ML25037A063
| ML25037A063 | |
| Person / Time | |
|---|---|
| Site: | 99902071 |
| Issue date: | 02/07/2025 |
| From: | Dukes O NRC/NRR/DANU/UAL2 |
| To: | |
| References | |
| Download: ML25037A063 (1) | |
Text
1 NOTES FOR THE NOVEMBER 12, 2024, OBSERVATION MEETING WITH X ENERGY, LLC, TO DISCUSS XE-100 PLUME EXPOSURE PATHWAY EMERGENCY PLANNING ZONE (EPZ) SIZING METHODOLOGY The table below contains the questions and corresponding responses for the topics discussed during the meeting.
NRC Question X-energy Response (Slide 6) Does this topical report take into account the 4-pack Xe-100 unit, such as planned for Project Long Mott, or does the topical report only focus on one Xe-100?
Yes, the topical report accounts for the 4-pack Xe-100 unit.
(Slide 8) How is X-energy leveraging the NEI seismic scenario white paper, Selection of a Seismic Scenario for an EPZ Boundary Determination dated May 2024 (ML24187A096)? Is it referencing the whole discussion, or is it specific to a conclusion?
The white paper has multiple conclusions, X-energy is referencing the white paper in this topical report. However, while it is leveraging the white paper for this topical report, the topical report will provide all the necessary information to support the NRC staff finding.
The seismic white paper will not be incorporated by reference, instead X-energy will extract any needed information from the white paper and include it in the topical report.
(Slide 9) X-energy planned to use probabilistic risk assessment (PRA) and NEI 24-05, "An Approach for Risk-Informed Performance-Based Emergency Planning,"
for licensing basis events (LBEs); How will that be addressed in the security concepts?
Will it be addressed in this topical report?
Security concerns are not addressed in this EPZ Sizing topical report consistent with the NEI 24-05 guidance document.
(Slide 9) Per the bullet regarding 10 CFR 50.160, will the topical report identify which potential exemptions X-energy may need if the methodology for the topical report is approved?
There will be no need for exemptions. The need for exemption is obviated by new regulation (i.e., 10 CFR 50.160).
(Slide 10) Is X-energy making direct reference to NEI 24-05 in this topical report?
The NRC staff noted that NEI 24-05 is still under review and also noted the risk associated with referencing a report that is under review.
Yes, X-energy intends to directly reference NEI 24-05.
X-energy discussed referencing 10 CFR 50.160 and NEI 24-05. For some concepts in NEI 24-05, security concerns are not necessarily addressed; however, 10 CFR 50.160 requires that security is included as part of spectrum of requirements.
The justification for the security events in NEI 24-05 includes that LBEs used to establish EPZ size should encompass the regulations to protect against design basis event (DBE) and beyond design basis event (BDBE) threats.
(Slide 14) What is the time frame for the 200 rem?
96 hours0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br />.
2 (Slide 12) Did X-energy discuss cutoffs in the presentation? It should consider uncertainty and be determined based on the likelihood of events based on facility, and the analysis should confirm that there is adequate defense in depth. The analysis should be unique to the Xe-100 reactor.
Results will be obtained for PRA. Uncertainty and cliff-edge will be discussed in more detail later in the presentation.
(Slide 18) In accordance with 10 CFR 50.160(b)(1)(iii)(B), applicants shall ensure that the capability exists to implement and maintain protective actions for onsite personnel for emergency conditions and recommend protective actions to offsite authorities as conditions warrant. This is applicable even if its identified that No PEP EPZ exists beyond facility structures OR the PEP EPZ is at the Site Boundary. It should be noted that there is still an action on the applicants behalf for offsite communication capabilities to protect constituents. This information should be detailed in the TR.
X-energy understands the need for engagement.
(Slide 14) NRC staff need to fully understand the basis for the use of the specific criteria, and the 200 rem criterion at 96 hours0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br /> being an acute dose. The items that X-energy is referencing are from NEI 24-05 which is still under review.
Understood.
Public Question NRC Response Is the NRC staff creating guidance for how the security-based events will be considered and addressed in EPZ sizing methodology?
Yes, NRC staff are currently looking at methods to provide further guidance in the next revision of RG 1.242, Performance-Based Emergency Preparedness for Small Modular Reactors, Non-Light-Water Reactors, and Non-Power Production or Utilization Facilities.
How are uncertainty and cliff edge analyses being considered in meetings with applicants, and is this information being shared amongst other stakeholders (including other applicants)?
The review of the NEI 24-05 document will support this. The NRC staff will take any needed changes under consideration for incorporation into NRC guidance documents.
NRC staff also discussed the importance for applicants to fully participate in these public engagements.