Calculation of the Dose Rate and Air Ionisation from Radioactive Fallout Deposited at Chilton, Oxon (1951 to 1977)

摘要

This report is a brief survey of the methods used for calculating the dose rate from deposited fallout and includes improvements in the computing techniques. The changes consist of (a) the use of a more exact allowance for weathering (b) the calculation doses to mid-month rather than end of each month (c) the inclusion of the contribution from Nb-95 in a more exact way to allow for its build-up and decay with time (d) the use of a more precise method for estimating the dose prior to 1954. The result is to increase the calculated total gamma -ray dose from 1951 to 1976 by 17% from 153 to 179 mrad in air at 1 m with an increase of 11% in the beta-ray dose. The annual levels for natural gamma and beta radiation are 12 and 62 mrad respectively. (Atomindex citation 10:426141)