In using new materials in irradiation environments in which high-energy corpuscular beams are emitted and occurrence of severe irradiation damage is expected, it is necessary to evaluate beforehand usability and long-period soundness of materials in these environments. Hence, in prior art, an irradiation test plan in which environments are simulated is first formulated, irradiation experiments in which many irradiation conditions are parameterized are conducted, and obtained systematic post-irradiation examination (PIE) data is analyzed to thereby obtain practical conditions in which materials can be used under irradiation.
However, in order to conduct a high-accuracy evaluation analysis that can ensure high safety and reliability during use of materials, a long period and much cost for an enormous number of tests and a sufficient analysis are required. For example, in development of materials for fission reactors in study of light-water reactors and high-temperature gas reactors, and development of materials for nuclear fusion reactors, in a case where new materials that have no irradiation result are used in irradiation environments, development of new materials represented by Zircaloy, HASTELLOY XR (an Ni—Mo—Cr(Fe) based alloy), austenitic stainless steels, fine-grained isotropic graphite, and the like has required a development period on the order of 10 years and an enormous development cost has been indispensable.
Therefore, as described in the following Reports 1-4, there have been available methods by which multiple research institutes store enormous irradiation data in collaboration by assembling an irradiation database on materials and use this data in analyses. Under present circumstances, however, such methods have not yet reached a stage at which irradiation data can be systematically analyzed, and there is no analysis solution, calculation code or data base capable of easily deriving practical conditions for use.
A description of irradiation damage to materials is very complex. Irradiation damage starts with collision of high-energy particles and is composed of instantaneous heating and cooling processes and various reaction processes, such as atomic displacement, generation, growth and diffusion of defects, aggregation and coalescence of defects, and initiation and propagation of cracks. Although part of these reactions are expressed by mathematical formulae such as a diffusion equation, almost all of these reactions require high-speed and large-capacity processing by a computer on the basis of statistical processing by molecular dynamics, the Monte Carlo method and dislocation dynamics. For this reason, because at present there is a limit to calculating performance of computers, it is difficult to analyze an entire picture of irradiation damage and to systematically grasp the irradiation damage even if a next-generation super computer is used. Furthermore, there is no evaluation formula that enables a description of irradiation damage to be reflected in an evaluation of material characteristics and, therefore, it has hitherto been impossible to instantaneously derive practical conditions under which materials can be used under irradiation (practical conditions for use).
A problem to be solved by the present invention is that in pursuing application of new materials represented by ordered alloys subjected to irradiation environments, there is no method of judging practical conditions for use of the materials under irradiation in a short period and at low cost and that for this reason, it has been difficult to introduce materials that have no irradiation result.
Report 1: Shuichi Iwata et al., Materials Data Base for Fusion Reactors-1, Journal of Nuclear Materials, Vol. 103 (1982), pp. 173-177.
Report 2: Hajime Nakajima et al., Present status of Data-Free-Way—Distributed database for advanced nuclear materials, Journal of Nuclear Materials, Vol. 212/215 (1994), pp. 1711-1714.
Report 3: Mitsutane Fujita et al., Application of the distributed database (Data-Free-Way) on the analysis of mechanical properties in neutron irradiated 316 stainless steel, Fusion Engineering and Design, Vol. 51/52 (2000), pp. 769-774.
Report 4: Yoshiyuki Kaji et al., Status of JAERI Material Performance Database (JMPD) and Analysis of Irradiation Assisted Stress Corrosion Cracking (IASCC) Data, Journal of Nuclear Science and Technology, Vol. 37 (2000), pp. 949-958.
USPTO Backgrounds
USPTO Backgrounds