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:
1.42-C4 where p on vege ij is the quantity of radiolodine i in curies per square meter tation at the location of interest. Annual Infant Thyroid Dose Via Cows Milk Milk cattle pastured on green fodder containing iodine secrete a portion of the iodine ingested into their milk. Several authors3,5,6,12,14,15,17-20 have measured or calculated (using the measurements of others) the concentration of radioiodine in milk of cattle pastured on forage with measured areal activity densities. Based on this information, an iodine transfer coefficient, k 2, was found to range from 0.014 to 1.54 curies/liter per curie/square meter, with average values ranging from 0.09 to 0.40 for 1-131. A value of 0.20 has been selected as appropriate to represent the 1-131 transfer coef- ficient, k 2, for purposes of this model. Upon application of appropriare 21 parameters and relationships , the value of the iodine transfer coef- ficient for 1-133 has been calculated to be 0.09 curie/liter per curie/ square meter. The values assigned to iodine transfer coefficients are, of course, dependent upon the quantities of green fodder ingested per unit time by the cow. However, given free access to pasture, cows have been shown22 to ingest a nearly constant weight of grass per day over a large weight range of daily concentrate intakes. As a consequence of this, no allowance is provided for iodine concentration reduction in milk due to supplemental feeding of cows that are allowed to graze freely. It might also be expected that the addition of inactive iodine to the diet of a cow could provide some reduction of radioiodine concentration in milk. This is true, but the iodine intake requirements of the cow must be quite large to affect the iodine transfer coefficients. 1. 42-C5 0 It has been reported21 that as much as 2 grams of iodine per day results in only a 50% reduction in milk radioiodine concentration and that, within a rather large range, the iodine content of a cow's diet has little effect on the