| With the continuous development and utilization of nuclear energy,nuclear safety and nuclear emergency response have increasingly become the focus of attention of all countries,and the requirements for robots that can be used in nuclear emergency relief and rescue are also increasing.Combined with nuclear plant at the time of the accident of radioactive environment,with independent research and development of the laboratory design target demand"gourd dollⅢ"robot as an example analysis shows that in order to make it to the remote remote control operations,complete response command corresponding to a variety of actions,the nuclear emergency robot electronics box of radiation protection is particularly important.In the event of an accident in a nuclear power plant,the nuclear emergency robot needs to enter a highly radioactive environment for rescue and relief work,which is likely to cause great damage to electronic devices.The key to the disaster relief mission is that the nuclear emergency robot still maintains normal working ability under radiation conditions.In the electronic device box,the radiation resistance of the controller is relatively weak.Therefore,it is important to understand the radiation resistance of the controller in the electronic device box,and to design the corresponding shielding device according to the radiation resistance of the controller.This paper first investigates the radiation shielding technology of electronic components,the radiation shielding reinforcement method,introduces the epec2024 controller and the failure principle,and introduces the radiation damage mechanism from the total dose effect,the radiation damage effect of components and related factors.The radiation damage mechanism of the nuclear emergency robot is described.The effects of radiation environment with high dose of gamma rays on the controller with semiconductor as the main structure are described.The effects of external related factors on the radiation damage of the controller are analyzed.The radiation source was 60Co.The experiment was carried out in Liuyang City,Hunan Province.The dose rate was20Gy/h,50Gy/h,75Gy/h and 100Gy/h respectively.MCNP simulation was carried out.After a series of analysis,in the pure metal shielding performance indicators:The linear attenuation coefficient（μm）and mass attenuation coefficient（μm）compared to explore the mass attenuation coefficient,the identified with tungsten as matrix material,mixing of other elements in tungsten alloy to improve tungsten mechanics performance,thermal performance,shielding performance,finally realizes the nuclear disaster relief robot electronics material shielding box optimization design.Then the model is constructed.The shielding properties of different tungsten-nickel combinations and alloys were explored.Through the calculation results of transmittance,the conclusion was drawn that the Ni-W composite shielding effect was the best in the experiment of single-layer shielding structure.The effect of increasing the thickness of the shielding layer on the shielding effect is calculated.When the thickness reaches 5cm,the shielding efficiency is more than 90%,which basically meets the shielding requirements of the electronic device box and can ensure the normal operation of the robot in the irradiation environment.The optimized design of the shielding layer based on the determined thickness was carried out.The stratified sampling of the 5cm thickness was carried out by using genetic algorithm.The layers were randomly divided into three layers and randomly assigned with materials,which were selected and numbered from tungsten,tantalum,lead and iron.It is concluded that in the 200th generation,it has basically converged to a compact distribution along the front line.Based on the weight and surface flux of the initial scheme,10 optimal schemes that are better than it can be found in the lower left corner.The adjacent schemes are regarded as similar schemes to be cut down,and five schemes are finally selected.The epec2024 controller can still work normally after 3 times of irradiation time in unshielded state.It is concluded that the design scheme of the shielding structure can safely and effectively prolong the service time of the epec2024 controller.The external shielding scheme was designed for the strong radiation field,and the neutron and photon transport calculations were carried out to explore the influence of different distances and different superimposed shielding methods on the shielding effect.The shadow shielding is made of B4C and Be materials with lighter weight and better neutron shielding effect,and the local shielding at the back end is made of W and B4C materials.In this part,the shielding design scheme and calculation results of electronic device box are given. |
