ML25057A400
| ML25057A400 | |
| Person / Time | |
|---|---|
| Issue date: | 02/25/2025 |
| From: | Tanya Smith NRC/NSIR/DPR |
| To: | |
| References | |
| Download: ML25057A400 (1) | |
Text
1 Potassium Iodide Policy Implementation Todd Smith, PhD Senior Level Advisor for Emergency Preparedness and Incident Response
2 Potassium Iodide policy in the U.S.
- NRC regulations require consideration of KI as a supplemental protective action regulations and guidance are specific to large light water reactors
- Federal Policy on Use of Potassium Iodide (KI), 67 FR 1355, 2002 KI should be stockpiled and distributed for emergency workers, institutionalized persons, and considered for the public within the 10-mile emergency planning zone
- Bioterrorism Act of 2002 requirement to distribute KI out to 20 miles around nuclear power plants; waived because more effective protective measures exist
3
- radioiodine biokinetics
- optimal timing of intake
- feasibility and acceptability
- best practices for stockpiling or pre-distribution WHO recommends further KI research:
World Health Organization, Iodine thyroid blocking: Guidelines for use in planning and responding to radiological and nuclear emergencies, WHO 2017.
https://www.who.int/publications/i/item/9789241550185
4 U.S. KI policy is evidence-based
- Efficacy and efficiency of KI implementation could benefit from modernization
- KI Subcommittee within the Federal Radiological Preparedness Coordinating Committee (FRPCC) has been reinstated to assess need for guidance
- KI guidance can benefit from:
insights on radioiodine release from state-of-the-art consequence analyses lessons from Chernobyl, Fukushima and Ukraine adequacy of dietary iodine sufficiency and daily iodine intake understanding of advances in nuclear technologies best practices
5 KI effectiveness can be modeled Kimura, M., Oguri, T., Ishikawa, J., & Munakata, M. (2020). Development of an evaluation method for planning of urgent protection strategies in a nuclear emergency using a level 3 probabilistic risk assessment. Journal of Nuclear Science and Technology, 58(3), 278-291. https://doi.org/10.1080/00223131.2020.1820914 SI: stable iodine
6 MACCS can inform KI strategies What is MACCS?
MELCOR Accident Consequence Code System Analysis tool for developing realistic estimates of consequences of nuclear power plant incidents Developed by NRC and Sandia National Laboratory Extensive use by NRC and domestic and international organizations How is MACCS used?
Consequence studies Level 3 Probabilistic Risk Assessment (PRA)
Cost-benefit analysis Risk-informed decision-making
7 MACCS can inform KI strategies NRC is using MACCS to assess effectiveness of KI implementation KIMODL determines whether to consider KI or NOKI Linear no threshold (LNT) dose-response model applied Dose to a population is reduced by a factor 1 x
- where, EFFACY reduces the dose to the thyroid from inhalation POPFRAC is the fraction of a cohort that ingests KI
8 KI effectiveness depends on many factors Ioannis Ilias, Manfredi Rizzo, Georgios Meristoudis. Potassium Iodide in Nuclear Accidents: Give it Timely, Swiftly and Judiciously, Endocrine, Metabolic & Immune Disorders - Drug Targets; Volume 23, Issue 6, Year 2023, e141022210042. DOI:
10.2174/1871530323666221014150729 To be effective against inhalation exposure, KI must be administered within a specific window of opportunity
< 12-24 hours before exposure ~90% to 70% effective
< 1-3 hours after exposure ~85% to 50% effective
> 6 hour6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> after exposure has negligible protective effect Modeling can provide useful insights for informing KI implementation. Factors include:
source term (optimal timing and radioiodine form)
KI time dependency (biokinetics) iodine sufficiency (biokinetics) distribution strategy (feasibility) human factors (acceptability) state of practice (best practice)
9
- Real events provide insights on KI use and best practices
- Regarding radioiodine:
children are most at-risk ingestion pathway is important KI intake is not 100%
thyroid screening resulted in overdiagnosis and anxiety
- Nonradiological health effects can outweigh radiological risks
10 Data will inform MACCS parameters The rate of distribution was 94.9%, but the intake rate was only 63.5%. Intake was lower in those aged 0 to 2 years compared with those aged 3 years (OR, 0.21; 95% CI, 0.11 to 0.36). Parents intake was positively associated with their childrens intake (OR, 61.0; 95% CI, 37.9 to 102.9). The variance partition coefficient for regions was 0.021, suggesting that the intake of stable iodine was more likely affected by individual than by regional factors. Closed-ended questions showed that the main reason for avoiding intake was concern about safety. Open-ended questions for other reasons revealed issues related to the distribution method, information about the effects and adverse effects of iodine, and instructions for iodine intake. There were no symptomatic adverse effects claimed to the town.
11 Other countries are using MACCS to assess KI use Jia Hao Tang, Sung-Yeop Kim, (KAERI), 2024 International RAMP and MACCS User Group Meeting, Rockville, MD, Oct 21-25, 2024
12 Potential scenarios to model in MACCS No KI KI pre-distributed KI picked up at distribution centers/shelters KI stockpiled - delivered when and where needed
13 RAMP codes inform use of other measures
14 The time to prepare for advanced nuclear is now