Adopt NUREG 1.109 approach.

Problem is addressed in three stages.

Stage 1: Concentration of radioactive material in vegetation (C_iv)

The expression used to derive C_iv is eq. A-8 on p. 1.109 - 15. Two components contribute to the total activity concentration.

Component 1 given in the first term of the bracketed expression refers to direct foliar deposition. This term is neglected as this is specifically excluded from the brief.

Component 2 refers to the uptake of radioactivity into vegetation from soil and can reflect long term deposition due to operation of a facility.

The modified expression taken from eq. A-8 for use in the project will therefore be:

where

C_iw - Bq× l^-1 of nuclide i in water used for irrigation

I - L× m^-2× h average irrigation rate during growing season

f_i - fraction of year which crops are irrigated

B_iv - soil to vegetable radionuclide concentration factor

r - effective surface density of soil kg× m^-2

l _i - radiological decay constant

t_b - period of time for which soil is exposed to contaminated water

t_h - hold-up time between harvest and consumption

In the current case, t_b will be assumed to be one year and t_h will be zero, and so exp(-l _i× t_h) will therefore tend to one.

The radionuclide concentration in an animal product such as meat or milk is dependent on the amount of contaminated feed or forage eaten by the animal and its intake of contaminated water.

In the current case, the intake of contaminated water is neglected.

The radionuclide concentration C_im in milk is given by eq. A-11 of NUREG 1.109 on p. 1.109 - 16.

where

F_im - stable element transfer coefficient relating daily intake rate by an animal to concentration in milk, day× L^-1.

Q_v - Consumption rate of contaminated vegetable matter, kg× day^-1.

Stage 3: Dose to man from ingestion of contaminated milk

The dose D_i, is simply the product of the radionuclide concentration in milk C_im, the annual intake of milk Q_m, and the ingestion dose coefficient for the particular nuclide:

thus

Note: the above equations can be adapted to provide concentrations of radionuclides in various crop types using the appropriate transfer values. Dose to the consumer may then be calculated in a manner similar to the above example but using the appropriate consumption factors for the various crop types.