Document: NRC Regulatory Guide
Document ID: 0cfc3978-32da-4370-9f31-8a3547d82846
Document Type: regulatory_guide
Title: Assumptions Used for Evaluating the Potential Radiological Consequences of a Fuel Handling Accident in the Fuel Handling and Storage Facility for Boiling and Pressurized Water Reactors (Rev. 0)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML0833/ML083300022.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.25
CFR Part: 
CFR Title: 

Content:
from radioactive clouds: a. The assumptions relative to inhalation thyroid dose approximations are: (1) The receptor is located at a point on or beyond the site boundary where the maximum ground level concentration is expected to occur. (2) No correction is made for depletion of the effluent plume of radioiodine due to deposition on the ground, or for the radiological decay of radioiodine in transit. (3) Inhalation thyroid doses may be approximated by use of the following equation: ) DF )( DF ( ) Q / χ ( IFPBR F D f p g = Where: D = thyroid dose (rads) Fg = fraction of fuel rod iodine inventory in fuel rod void space (0.1) I = core iodine inventory at time of accident (curies) F = fraction of core damaged so as to release void space iodine P = fuel peaking factor B = breathing rate = 3.47 × 10-4 cubic meters per second (i.e., 10 cubic meters per 8 hour work day as recommended by the ICRP) DFp = effective iodine decontamination factor for pool water DFf = effective iodine decontamination factor for filters (if present) χ/Q = atmospheric diffusion factor at receptor location (sec/m3) R = adult thyroid dose conversion factor for the iodine isotope of interest (rads per curie). Dose conversion factors for Iodine 131-135 are listed in Table I.9 These values were derived from “standard man” parameters recommended in ICRP Publication 2.10 9 Dose conversion factors taken from “Calculation of Distance Factors for Power and Test Reactor Sites,” TID-14844, J. J. DiNunno, R. E. Baker, F. D. Anderson, and R. L. Waterfield (1962). 10 Recommendations of the International Commission on Radiological Protection, “Report of Committee II on Permissible Dose for Internal Radiation (1959),” ICRP Publication 2, (New York: Pergamon Press, 1960). RG-1.25, Page 7 Table 1. Adult Inhalation Thyroid Dose Conversion Factors IODINE ISOTOPE CONVERSION FACTOR (R) (RADS/CURIE INHALED) 131 1.48 × 106 132 5.35 × 104 133 4.0 × 105 134 2.5 × 104 135 1.24 × 105 b. The assumptions