ML26036A341
| ML26036A341 | |
| Person / Time | |
|---|---|
| Site: | 99902130 |
| Issue date: | 02/05/2026 |
| From: | NRC |
| To: | NRC/NRR/DANU |
| References | |
| Download: ML26036A341 (0) | |
Text
From:
Denise McGovern Sent:
Thursday, February 5, 2026 5:09 PM To:
EnergyNorthwestX-SafPUBLICem Resource
Subject:
Follow-up questions from ENNN Volcanic White Paper presentation Attachments:
ENNN responses to NRC questions on volcanic presentation.docx This is a follow up to a public meeting held on January 27, 2026.
Meeting information ADAMS No. ML26026A098 Denise McGovern Senior Project Manager U.S. Nuclear Regulatory Commission NRR/DANU/UAL2 301.415.0681 From: Clark, Nathan D. <ndclark@energy-northwest.com>
Sent: Thursday, February 5, 2026 4:31 PM To: Denise McGovern <Denise.McGovern@nrc.gov>
Cc: Williams, Lisa L. <llwilliams@energy-northwest.com>; Gregoire, Donald W. (Contractor)
<dwgregoire@energy-northwest.com>; Moen, Stephan C. <scmoen@energy-northwest.com>; Slavens, Crystal D. <cdslavens@energy-northwest.com>; Boswell, Greg <gregory.r.boswell@sargentlundy.com>
Subject:
[External_Sender] follow-up questions from ENNN Volcanic White Paper presentation
- Denise, Please see the attached responses to the questions during the volcanic hazard presentation last week, 1/27/26. Let me know if the Staff have any additional questions.
Thank you, Nathan Clark Licensing Supervisor l New Nuclear Development Office 509.377.6069 l Mobile 509.480.9120
Hearing Identifier:
EnergyNorthwestX_CPSafDocs_Public Email Number:
3 Mail Envelope Properties (SA9PR09MB48301FA392D4FC6B3906DB3CE299A)
Subject:
Follow-up questions from ENNN Volcanic White Paper presentation Sent Date:
2/5/2026 5:09:20 PM Received Date:
2/5/2026 5:09:24 PM From:
Denise McGovern Created By:
Denise.McGovern@nrc.gov Recipients:
"EnergyNorthwestX-SafPUBLICem Resource" <EnergyNorthwestX-SafPUBLICem.Resource@nrc.gov>
Tracking Status: None Post Office:
SA9PR09MB4830.namprd09.prod.outlook.com Files Size Date & Time MESSAGE 1093 2/5/2026 5:09:24 PM image001.jpg 810134 ENNN responses to NRC questions on volcanic presentation.docx 21422 Options Priority:
Normal Return Notification:
No Reply Requested:
No Sensitivity:
Normal Expiration Date:
ENNN Responses to NRC Questions from 1/27/26 Volcanic White Paper Presentation What computer program was used for original Columbia tephra analysis?
- From the description in TM-1250, it appears that no modeling of volcanic ashfall was done. Rather, the design basis values were determined from evaluation of several reports.
The information to support these findings has been abstracted from the references cited in each subparagraph of section 1 of this report. These have been acquired primarily as the result of work performed at (1) Battelle Pacific Northwest Laboratories, (2) U.S. Department of Energy - Bonneville Power Administration, and (3) numerous discussions with scientists from both the academic and private sectors. Appendix A is a compilation of Figures and Tables from these sources with the applicable references. The results were discussed and coordinated with the AE for the WNP-1 and 4 Project, in order to assure uniformity of ash parameters between the two closely located sites.
The 2020 USGS study used ASH3D. What model did the 2011 study use?
ASH3D was issued in 2012 so was not available for USGS 2011. From discussion of P(3l2) in the 2011 report, it appears that they used a ranking table based on 14 historical volcanoes to get probabilities for exceeding a given ashfall depth at 200 km from the source rather than a computer model. From the 2011 report, To calculate tephra exceedance probabilitythe probability that an eruption will deposit tephra whose thickness at a given distance from its source will be greater than or equal to a specified valuewe first rank the empirical observations from highest to lowest, with the greatest value assigned a rank of 1. The exceedance probability for a thickness value of rank m is m/(n+1), where n is the number of data points. Results for the 14 eruptions with data extending to 200 km from source are tabulated in table 3. Consequently, it appears that no computer modeling of ash transport such as ASH3D performs was used.
Were there any considerations to changing the tectonic models between the 2011 and 2020 USGS studies?
One 2017 reference in the 2020 report includes tectonic in the title. Otherwise, the 2020 study adopted the 2011 studys eruption probability and used historic information to determine ashfall quantities and characteristics. I found no indication of an attempt to make adjustments based on new tectonics, though theres recognition that tectonics changes that could affect eruptions had occurred. See Appendix 2, Introduction 1.
larger pre-Holocene eruptions did not reflect the current composition and (or) size of the magma system.
o Coltice, N., Gérault, M., and Ulvrová, M., 2017, A mantle convection perspective on global tectonics: Earth-Science Reviews, v. 165, p. 120-150.