2.25 MEASURED DIRECT RADIATION


    When measurements are available to characterize radiation fields where people are expected to reside, an estimate of the health impacts from direct radiation exposure to the fields may be made.
Transport Medium:
direct radiation dose rate for radiation transport from source to the exposed individual, rem/yr, expressed as an instantaneous dose rate

Special Process:
reduction of dose rate with time according to a user-defined half-time

Exposure Factors:
exposure rate and exposure duration.

The total lifetime dose from external exposure to measured radiation fields is evaluated as follows:

(111)



where
and 365.25 is as previously defined.

    The user may supply a value for the dose reduction half-time from which the effective rate constant, ldr, is evaluated. If no value is given for the half-time, the dose rate is assumed to be constant over time.