Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Izawa, Kazuhiko; Aoyama, Yasuo; Sono, Hiroki; Ogawa, Kazuhiko; Yanagisawa, Hiroshi; Miyoshi, Yoshinori
Proceedings of 9th International Conference on Nuclear Criticality (ICNC 2011) (CD-ROM), 11 Pages, 2012/02
For reactor physics and criticality safety researches, the Static Experiment Critical Facility (STACY) will be modified. In the modification, the present STACY, solution-fuel-type homogeneous cores, will be converted to fuel-pin-type heterogeneous cores moderated by light water. For nuclear safety design of the modified STACY, computational analyses have been carried out by using a Monte Carlo code MVP and a transport code system DANTSYS with cross-section data based on the JENDL-3.3. In the analyses, basic nuclear characteristics have been evaluated, such as criticality, water-level worth and reactor shutdown margin. By the results of these analyses, the feasibility of reactivity control mechanism and the sufficiency of reactor shutdown margin of the modified STACY were confirmed. In addition, temperature and void coefficients of reactivity and kinetic parameters were obtained to comprehend nuclear characteristics of the modified STACY.
Tonoike, Kotaro; Miyoshi, Yoshinori; Uchiyama, Gunzo
Proceedings of 9th International Conference on Nuclear Criticality (ICNC 2011) (CD-ROM), 11 Pages, 2012/02
Several series of critical experiments have been conducted in the Static Critical Experiment Facility (STACY) to measure critical volume of low-enriched uranyl nitrate solution. Its purpose is to obtain critical benchmark data for validation of computation methods used in the criticality safety analysis of nuclear facilities, especially, reprocessing plants. The experiment series are: homogeneous single-unit system, homogeneous multi-unit system, and heterogeneous system. Experimental conditions such as core tank geometry and fuel solution composition, and measurement results of critical volume were carefully and precisely evaluated to produce critical benchmark data. Sensitivity analysis on uncertainties of such experimental conditions was conducted to estimate overall uncertainties of the benchmarks. In this report, features of each experimental system will be highlighted by describing results of the experiments and the sensitivity analysis. Also presented will be lessons leaned from the experimental and evaluation experience which might be valuable for design of future critical experiments.
Tonoike, Kotaro; Suyama, Kenya; Okuno, Hiroshi; Miyoshi, Yoshinori; Uchiyama, Gunzo
Proceedings of 9th International Conference on Nuclear Criticality (ICNC 2011) (CD-ROM), 8 Pages, 2012/02
The 1st version of criticality safety handbook of Japan was published in 1988. A criticality safety analysis code system JACS was validated, and minimum critical mass and safety limit mass of various fissile materials were calculated. During more than two decades since then, new critical experimental data were taken in the Static Critical Experiment Facility (STACY), and more precise benchmark data of wider range of fissile materials were accumulated by the International Criticality Safety Benchmark Evaluation Project (ICSBEP). Computational capability has greatly grown, and new codes and nuclear data have been developed. The 2nd version of the handbook utilizes the results of validation of the criticality analysis method with a continuous energy Monte-Carlo code MVP and a nuclear data library JENDL-3.2 using the benchmark data chosen from the ICSBEP handbook. Results of the benchmark calculation were statistically studied, from which the safety limit value of multiplication factor was derived as 0.98. Based on the conclusion, minimum critical mass and safety limit mass were calculated. Future plan of research activities on the criticality safety in JAEA will be also overviewed.