Document: NRC Regulatory Guide
Document ID: c0dbb594-6262-4b83-96b1-366758ad9676
Document Type: regulatory_guide
Title: Interim Licensing policy on as low as Practicable for Gaseous Radiodine Releases from Light-Water-Cooled Nuclear Power Reactors (Rev. 1)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1229/ML12298A137.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.42
CFR Part: 
CFR Title: 

Content:
tion as 0.30 and 0.23, respectively, the daily depositions of radioiodine within the thyroid by goat milk ingestion and air inhalation are given by: Daily Thyroid Deposit (milk) = (0.30)(0.70) nij and Daily Thyroid Deposit (inhalation) = (0.23)(3) C The ratio of goat milk to air thyroid doses for the same air concen- tration is (0. 30) (0.70)n' Wi = (0"23)(3)Ci j (17) A These ratios for 1-131 and 1-133 are then 1220 and 90, respectively. Thus, the calculation of infant thyroid dose via the goat milk pathway may be related directly to those air concentration values provided in 10 CFR Part 20 that correspond to air doses of 1500 millirem per year to an infant's thyroid. These are given below: Annual Infant Thyroid Dose Via Nuclide Goats Milk (mrem) 1-131 (1220)(-•e Mp (1500) a 1-133 (90) (cUi-) (1500) MPC )(50 a Alternative representations of the above are: Dl 31 (mrem/yr) = 5.82 x 108 (x/Q)QR (18) W D1 3 3 (mrem/yr) = 1.07 x 10 7 (x/Q) Q1 33R (19) 0 1. 42-ClO In Equations 18 and 19, (x/Q)j is given in seconds per cubic meter, Q is given in curies per year, and R (from Equation 2) is dimensionless. As indicated in the discussion of infant thyroid dose via the cow milk pathway, doses calculated per Equations 18 and 19 are annual doses and may be reduced by that proportion of the year that goats are actually pastured. Annual Adult Thyroid Dose Via Leafy Vegetables The equilibrium areal density of radioiodine i on vegetation is as given in Equation 5. The average United States production per unit area during 1971 of several leafy vegetables27 is as follows: Cabbage 2.47 kilograms per square meter Lettuce 2.38 kilograms per square meter Spinach 1.11 kilograms per square meter Upon normalization of these yields to relative total production,27 the average y•eld of leafy vegetables is estimated to be 2.34 kilograms per square meter. It is assumed that over a period of 3 months of a year the adult consumes 18 kilograms of fresh leafy vegetables. As a consequence, the rate