ML25204A201
| ML25204A201 | |
| Person / Time | |
|---|---|
| Issue date: | 07/24/2025 |
| From: | John Tomon NRC/RES/DSA/RPB |
| To: | Cindy Rosales-Cooper Office of Nuclear Security and Incident Response |
| Shared Package | |
| ML25204A195 | List: |
| References | |
| Download: ML25204A201 (1) | |
Text
MEMORANDUM TO:
Cindy Rosales-Cooper, Chief (acting)
Policy and Oversight Branch Division of Preparedness and Response Office of Nuclear Security and Incident Response FROM:
John Tomon, Chief Radiation Protection Branch Division of Systems Analysis Office of Nuclear Regulatory Research
SUBJECT:
CLOSURE OF INFORMAL ASSISTANCE REQUEST (IAR) NSIR-2024-012, EFFECTIVE USE OF MASKS DURING A RADIOLOGICAL EMERGENCY The purpose of this memorandum is to inform you that the Office of Nuclear Regulatory Research (RES) has completed the activities for Informal Assistance Request (IAR) NSIR-2024-012, Effective Use of Masks During a Radiological Emergency, (ML24269A133). For this IAR, the RES staff developed values of radiation doses from N95 and other types of mask usage during nuclear power plant (NPP) accidents. Use of the N95 mask blocks the inhalation of fission products (i.e., alpha/beta emitters such as radioiodines and gamma emitters such as radiocesiums) during the NPP accident which results in the transformation of the N95 mask into a new source term during the accident. This IAR builds on the Office of Nuclear Security and Incident Response (NSIR) 2020 sponsored project to explore the benefits of wearing a mask and the cost/benefit of designing an optimal mask for use in radiological emergencies. Please note that this IAR was submitted several months later than originally planned, due to Dr. Hansons paid parental leave.
The IAR completed the following task:
Task 1:
Dosimetry Assessment for Mask Usage.
CONTACT:
Sam Hanson, RES/DSA (301) 415-2097 July 24, 2025 Signed by Tomon, John on 07/24/25
C. Rosales-Cooper Perform a dosimetry assessment using RAMP computer codes (i.e., as Radiological Assessment System for Consequence Analysis (RASCAL), VARSKIN+ (V+), and the add Phantom with Moving Arms and Legs (PiMAL)) to determine dose. Specifically, looking at the particulate concentrations in the mask which is close to the thyroid or other sensitive organs to see not just the skin dose but also proximity dose due to the mask for a complete risk analysis.
Deliverables:
RES provided a report. Effective Use of Masking During Radiological Emergencies and Early Releases: Dosimetry Analysis Report, (ML25204A202) covering a complete dosimetry analysis of radiation dose consequences of wearing or not wearing multiple mask types. This report demonstrates that dose consequences of gamma activity captured on a face mask to the nearby thyroid, eyes, oral mucosa, as well as shallow skin dose from charged particle and ionizing photon to the skin near the mouth represent an overall decrease in risk from committed dose consequences of inhalation without a mask. It additionally compares these dose consequences to the alternative of committed dose from inhalation. All radionuclides that RASCAL lists as contributing to dose are analyzed to provide a full dosimetry analysis.
The report considers two severe RASCAL scenarios for commentary, one to mirror Fukushima accident air concentrations, and another to maximize chemical variety of particulate release. In the accessible IAR file, the entire Python script and several.csv files from data captured in all V+ and PiMAL with the Monte Carlo N-Particle (MCNP) runs are available. This script simply needs five lines changed to reorient its file pathways to fit ones own computer environment and then it may be run to determine similar results for any other open RASCAL files. This script also provides secondary information about the RASCAL run that is not available in the RASCAL GUI such as estimated air concentrations across all important contributors to dose and may potentially be the basis for future research into RASCALs capabilities.
As a result of this report, RES staff validated previous speculation that masking is an effective tool for dose reduction in a radiological emergency. Masks of various types and efficiencies, even worn with small air gaps can effectively reduce inhalation dose from particulate radionuclides significantly enough as compared to the alternative that masking should be listed as one of multiple strategies emergency responders can use to minimize risk to the public.
RES established an online Quality Survey to collect feedback from user offices on the usefulness of RES products and services. The Research Operating Plan System (ROPS) will send the MSEB staff Point of Contact (POC) a link to complete the Quality Survey. The email will be from RES OpPlan Admin RESOpPlanAdmin@nrc.gov with the subject line ROPS Work Request Survey. We would appreciate the recipient completing the survey within the next 5 working days to present your Offices views of the completed product and services.
- via eConcurrence 202550724-30022 OFFICE RES/DSA/RPB RES/DSA/RPB:
BC NAME SHanson JTomon DATE 07/22/2025 07/24/2025