Abstract
An optimization design and application of high temperature–resistant shielding material was carried out according to the nuclear power plant source characteristics and special protection requirements such as loss-of-coolant accident (LOCA). The composition of lead–boron polyethylene shielding composite was optimized based on the genetic algorithm and Monte Carlo methods and then realized by blending modification and graft copolymerization to improve its high temperature–resistant, shielding, and mechanical properties. Then comprehensive properties such as mechanical, neutron shielding, damp heat aging, irradiation resistance, and high temperature resistance were tested. These experiments proved that the high temperature–resistant lead–boron polyethylene shielding composite has excellent performance; especially, as it is able to keep a complete structure in a high-temperature environment of up to 190°C for 48 h. Finally, the shielding composite was applied to the shielding door design of a reactor pit chamber. When the shield thickness is 60 mm, the level of the neutron dose rate was reduced by 10 times, and that of the γ dose rate was reduced by 5 times, which meets all the requirements of radiation protection safety for nuclear power plants.
Highlights
The Hualong One reactor chamber adit requires effective shielding against neutrons and γ to reduce radiation from radiation sources such as reactor pressure vessels and main circuit systems so that the radiation dose rate of typical positions inside and outside the shielding door meets the requirements of the radiation zoning to ensure the safety of the staff, equipment, and environment
GENOCOPIII (Michalewicz and Nazhiyath, 1995; Michalewicz and Janikow, 1996) based on the genetic algorithm and MCNP 5 (X-5 Monte Carlo Team, 2003) and the Monte Carlo method are applied to the optimization design of the lead–boron polyethylene shielding composite according to the radiation field source terms of the Hualong One reactor pit chamber
When the 60-mm-thick lead–boron polyethylene shielding composite developed in this study is installed inside the shielding door, the maximum neutron dose rate outside the shielding door of the reactor chamber adit is 75 μSv/h, and the maximum γ dose rate is 48 μSv/h
Summary
The Hualong One reactor chamber adit requires effective shielding against neutrons and γ to reduce radiation from radiation sources such as reactor pressure vessels and main circuit systems so that the radiation dose rate of typical positions inside and outside the shielding door meets the requirements of the radiation zoning to ensure the safety of the staff, equipment, and environment. GENOCOPIII (Michalewicz and Nazhiyath, 1995; Michalewicz and Janikow, 1996) based on the genetic algorithm and MCNP 5 (X-5 Monte Carlo Team, 2003) and the Monte Carlo method are applied to the optimization design of the lead–boron polyethylene shielding composite according to the radiation field source terms of the Hualong One reactor pit chamber. The shear force can separate the macromolecular chains of the material to form free radicals, and some block and graft copolymerization will occur (Chen and Peng, 2011) so that the high-density polyethylene is suspended in the liquid phase of the blended material This can effectively improve the material’s ability to withstand high temperatures, making the melt of the improved lead–boron polyethylene shielding composite in a gel state at high temperatures and not producing softening deformation without an external force. Shielding door (composed of a steel structure and lead–boron polyethylene shielding composite)
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