Under the entrustment and support of the Chinese Academy of Atomic Energy, the Special Alloys Research Group of the Special Environmental Materials Research Department of the Institute of Metal Research, Chinese Academy of Sciences, and TGJT Stainless Steel Technology Group achieved the localization of stainless steel for the fourth-generation sodium-cooled demonstration fast reactor vessels and internal components.
The launch of the fourth-generation nuclear power sodium-cooled demonstration fast reactor project marks that China has become the sixth country to master fast reactor technology and is a key step in the national nuclear energy development strategy. The service conditions of sodium-cooled fast reactors are extremely harsh, and they have been exposed to harsh environments such as high temperature, corrosion, and irradiation for a long time. There is no domestic standard for materials used in these conditions. The structural materials in the early experimental reactor rely on foreign imports. In order to realize the independent construction of the demonstration fast reactor, it is urgent to establish technical standards for steel plates for key equipment to meet the safety and reliability requirements.
Sodium-cooled fast reactor stainless steel is used for a long time under high temperature, which requires high durability and creep performance, fatigue performance, and uniformity of structure. Especially in the case of medium carbon content, it must have intergranular corrosion resistance, with a thickness of 40 ~ The 90mm thick plate with a single weight greater than 12 tons makes it extremely difficult to produce. After more than three years of research, the researchers of the Metal Research Institute have selected the four materials used in foreign fast reactors as a 316KD stainless steel. Through the control of alloy elements and microstructures, the process is optimized to ensure that the materials take into account strong toughness, corrosion performance, Fatigue performance and endurance performance, etc., in order to meet the engineering design requirements for the material performance index, the technical standard (first edition) of 316KD plate for sodium-cooled fast reactor was formulated. Based on the preparation process parameters proposed by laboratory research, an industrialized trial production of 316KD was carried out in conjunction with the China Atomic Energy Institute and TGJT Stainless Steel Technology Group. The formation mechanism of ferrite in thick and large slabs is revealed and countermeasures are proposed to achieve the preparation of 316KD slabs with a ferrite content of less than 1%; a treatment process with medium carbon content 316KD stainless steel that has resistance to intergranular corrosion is proposed; The processing problem of thick steel plate with uniform grain size realizes the control that the grain size difference in the whole thickness direction of the steel plate does not exceed 2 levels.
At present, the production of 316KD stainless steel plates for the fourth generation nuclear power sodium-cooled demonstration fast reactor has been realized in TGJT Stainless Steel Technology Group. The homogeneity and performance of localized steel plates are better than similar foreign steel plates. The only qualified supplier of steel plate in China.