Radiation Protection Of The Place Of Nuclear Fuel Pellets Production And Research Of The Radiation Effects On Staff

This thesis comes from the scientific research project of Sichuan Provincial Health Department and the number is 100433. Since the rapid development of national nuclear power, there is an enormously increase in the demand of nuclear fuel. Meanwhile, the influence of nuclear fuel production to the human and the environment has become an important issue to the society.Currently, there is few researches about how nuclear fuel pellet production influents the health of staff. However, the radiation is quite intense in the workplace. If without complete preventive measure, it will lead to certain harmful effects. Thus, it is very important to go into the studies of the influence of radiation in Pressurized Water Reactor nuclear fuel pellet production to staff and measures to reduce the individual dose of radiation.Through on-site inspection and analysis of occupational radiation hazards of one Pressurized Water Reactor nuclear fuel pellet production line, we propose some radiation protection measures. We make dose estimation of production line radiation levels in the workplace and the individual dose operating staff exposed, which is compared with national standards. Develop a comprehensive analysis and evaluation of possible radiation effects of staff in nuclear fuel pellet production line. Furthermore, it proposes the measures to respond to the accidental incidents. Critical security issues on the storage of UO2 powder in the pellets production line need to be considered, this paper adopts the international advanced version of MCNP 5 Monte Carlo computer program to simulate the nuclear criticality safety analysis of UO2 powder treasury. The main conclusions are as follows:1,By taking some radiation protection measures such as workplace division, access control,device control,sealing, ventilation and purification, personal protection and so on, the max level of contamination on surface of device ofαis 3.77Bq/cm².These all consistent with the requirements of Ionizing Radiation Protection and Basic Standard of Safety of Radiation Sources (GB18871-2002),which request control limits of contamination on surface ofαis 40Bq/cm². 2,By taking some radiation protection measures such as workplace division, access control,device control,sealing, ventilation and purification, personal protection and so on, the max level of contamination on surface of groud ofβis range 0.09 from 3.38Bq·cm^-2, which is near barrel storage area. This value consistent with the requirements of Ionizing Radiation Protection and Basic Standard of Safety of Radiation Sources (GB18871-2002), which request control limits of contamination on surface ofβis 40Bq/cm².3,By taking some radiation protection measures such as workplace division, sealing, ventilation and purification and so on, the max level of aerosol concentrations ofαis 12.73 Bq·L^-1 and the value of ALI is 3.06×10³Bq, which is in press place. This value consistent with the requirements of Radiation protection regulations of uranium processing and fuel fabrication facilities (EJ1056-2005), which request control limits of ALI is 3.09×10⁴Bq. The max level of average of aerosol concentrations ofαis 8.89×10^-4Bq·L^-1, which is equal as 0.69DAC. This value meets the requirements of operating limits, which is below 1DAC or equal as 1DAC.4,By taking some radiation protection measures,the max level of Annual effective equivalent dose is 9.92mSv/a, which is lower than the requirements of GB18871-2002[52], which requsts 20mSv/a and is lower than the requirements of EJ1056-2005[51], which requsts 10mSv/a.Thses show that fuel pellet production line will not result in significant radiation hazard to staff.5,According to the subcritical limits of the UO₂ powder, whose water content is bellowed 1.5 (wt)% and less than half the density, we know that a single UO₂ powder material container is sub-critical safety equipment, and about 6 times higher than the safety factor. Through MCNP 5 program to simulate the criticality safety analysis of UO2 powder treasury, I can see the result of k eff increases first and then decreases, This rusult mainly due to a combination of factors such as the slowing, absorption and reflection of middle moderator water.When the density of the water is 0.4, the maximum value of k eff is 0.84152, which is bellowed 1. I can conclude that the criticality of UO₂ powder treasury is safe.6,This article provides the protective measures and emergency response corresponding to all kinds of abnormal and accident conditions, such as the possible leakage a large number of dust UO₂ and UO₂ powder erratum, and so on. These measures are feasible, as long as they can seriously implement safety measures. They can effectively prevent and reduce all cases of potential radiation exposure of workers.