Source Term Calculation And Analysis And Research

The calculation, analysis and the research of the radioactive source term are the basic aids and dependence for safety analysis of nuclear facilities, environment impact assessment, waste conditioning and decommissioning of nuclear facilities, etc. Nowadays in our country, we face the problem in decommissioning of nuclear facilities, spent fuel transport and waste disposal, etc. The unitl and unit2 of Dayabay have transported two bathes of spent fuel, some power reactor already started decommissioning, the research reactor-492 pool type reactor and 101 heavy water reactor in CIAE will be facing decommissioning too. At present in the world, there is not a good method which is unitized and effective, reasonable and economical for the long term disposal of high level radioactive wastes. Nowadays in our country, we are still absent of successful example for the experiences about reactor decommissioning, a set of Calculation, Analysis and Research (CAR) and useful results. Foreign countries have got experiences from the nuclear facilities have been or are being decommissioned, there has been formed a set of matured CAR of source term, successfully developed source term calculation and analysis programs which have been passed test verification, like ORIGEN series, KORIGEN, DECOM, FISPIN, etc. The International Atomic Energy Agency (IAEA) and the member states already have sets of matured criteria about control of radiation dangerous and the disposals of radiation wastes, and this has been provided a performance for the CAR.This report has reviewed the source term calculation and analysis of the real states of power reactors and Dayabay commercial reactor, and gave an estimated source term calculation and analysis for the China Advanced Research Reactor (CARR). This calculation choose the general computer code and calculation route which common in the world, for example, the calculation of spent fuel and in-core source term have been used the ORIGEN2 code, some external components source term calculation was combined with the MCNP code and ORIGEN2 code, MCNP code was used to calculate the neutron flux within the components, then, based on the geometry form of the components, using ORIGEN2 code to have a part by part calculation or general average calculation. Based onthe results of the source term calculation of different reactors in this report, it has been taken an analysis and research for the important nuclides of actinide, fission products and activation product; it has given instruction criteria for the concerned decay heat, long life radioactive nuclides and short life radioactive nuclides during the spent fuel transportation and disposal. The detail calculation has been carried out into components which is hard to detect during decommissioning, and for determine the accuracy of the calculation, a group of calculation results was chosen for compare with the measured data, mean while, the analysis and research for the disposal of short life nuclides and long life nuclides in high level waste has been carried out, especially the long term disposal problem for some extreme long life nuclides. The CAR has given the nuclides of actinide, fission product and active product which are important for radioactive inventory during disposal and transportation. The suggestion of disposal and transportation was given according the decay characteristic of the important nuclides, for example, the long life nuclides of actinide and fission products will not decay obviously during short term, it should be choose the long term geologic disposal.Different type reactor will use different library for the reason of different burn-up level, nuclear fuel characteristic, materials and cross section data, so, the calculation results will be quite different, but it'll solved by 0RIGEN2 code. A good estimate of the amount and type of radioactivity in spent fuel or nuclear facility are very important, because it can directly affect the whole approach to spent fuel transportation and disposal, all the same is the approach to decommissioning includi...