Co-60 Irradiation Facility Of Dose Distributions For The Calculation And Measurement

In this paper, according to the special characteristics of a large scale cobalt-60 gamma irradiation facility, a series of liquid Ag₂Cr₂O₇ chemical dosimeters with appropriate measuring range and performance of dosimetry have been prepared. These prepared chemical dosimeters have been used to measure the dosage distribution of multiple points distributed in the radiation field and within irradiated goods simultaneously. At the same time, base on Monte Carlo method, the theoretical calculations of the dosage distribution have been carried out, the calculated results are compared with those measured dosage data.The main achievements made in this paper are summarized as follows:1, The standard solution of Cr₂O₇^2- ions and Ag₂Cr₂O₇ chemical dosimeters have been prepared successfully. The molar extinction coefficient ε of the solution and the radiation chemical yield G of the chemical dosimeter have been specified and calibrated, two important parameters s and G which are used to determine the absorbed doses have been measured and calibrated respectively, they are ε=317.1m²·mor(-1) and G=3.77×10^-8 mol·J^-1 respectively.2, The dosimeters have been applied to the measurements of absorbed doses in the radiation field and inside the irradiated goods, the measured results have been traced to metrological standard. The measured results showed that they have indirect relative deviation of-3.0% with respect to Alanine/ESR dosimeters (metrological standard) of National Institute of Metrology. This proved that the preparation and application of our Ag₂Cr₂O₇ dosimeters are successful; the measured values of absorbed doses are reliable and precise.3, The dosage distribution of corresponding dosage measured points has been simulated by Monte Carlo method. The comparison between theoretical computation results and actual measurement data showed the relative deviation of computed data is coincident generally with the measured data, with relative errors about 10% in the radiation field and about 20% inside the irradiated goods. It showed that the computed results basically reflect the actual dosage distribution. Considering the actual situation that it is impossible to measure every dose point in the radiation field and inside the irradiated goods, computer simulation has a very important significance in associated scientific research and radiation processing industry.