Predigestion And Application Of SGS Technology In Measurement About Barreled Radioaction Waste From Decommissioning Of Nuclear Facility

With the development of the nuclear industry and technology, large amounts of radioactive waste will be produced. Our government has published a series of standards to strengthen the control of radioactive waste. Low and intermediate level radioactive waste(LILW) must be packed by 200 L steel barrel, the radionuclide composition must be given and activity must be accurately measured before the final disposal. Presently, instrument based on SGS used in analyzing waste of density less than 1.0g/cm3 was one of the best ways to solve the analyse of barreled radioactive waste. For most densities of the waste from the decommissioning programs are much higher than 1.0g/cm3, the application of standard equipments is limited. To resolve these measurement problems, efforts must be made to understand the analysis of these wastes. The main objective of the present study is to analyse the waste in the steel barrels from decommissioning of nuclear facility of our institute. The research of barreled radioactive waste non-destructive testing technology based on SGS is carried out. The main contents and results are as follows:(1)Design of testing equipmentMachine segment includes Horizontal transmission of waste barrel, Rotational support of waste barrel, Shield, Synchronous hoist of detector, and integrated framework. Application program segment includes drive control and ADC interface program.(2)Fitting detection efficiencyA user-defined parameter(absorption factor K),which is related to the medium absorption of transmission source is given. Fitting the relation between detection efficiency and absorption factor based on the experiment and theoretical calculation. The detection efficiency of detector is available through the measurement of barrel medium absorption of transmission source.(3)Crosstalk correctionAccording to the results of theoretical calculations and limits specified in the national standard, we proposed two reasonable assumptions on the basis of SGS to simplify crosstalk correction. A user-defined parameter(Count Correction Factor f), which is related to the medium absorption of transmission source is given. Fitting the relation between Absorption Factor and Count Correction Factor based on the experiment. The Count Correction Factor is available through the measurement of barrel medium absorption of transmission source, and can be used to correct the count number of interest region.(4) verification experimentThe verification experiments were carried out using simulated barreled radioactive waste prepared by 137 Cs standard liquor. The results showed that when the radioactive sources are random distribution and the medium density is less than 1.8 g/cm3, the error of calculation was less than 20%.