NRA has conducted a joint research program with the University of Tokyo to clarify how the pore sizes affect the adsorption reactions of different ions.

A system analysis code AMAGI (Advanced Multi-fluid Analysis code for Generation of thermal-hydraulic Information) has been developed as a best estimate code from its basic design. In the calculations using AMAGI on the void fraction experiments, technical knowledge was obtained on the differences between the AMAGI and TRACE models for each phenomenon and their impacts on the results.

Severe accident code, AZORES, is coupled with plant dynamics code for SFRs, ADYTUM. Accident progression between coupled and single AZORES simulations differs significantly.

Clearance measurement should be performed as a conformity assessment of the evaluated contamination values to the regulatory limit, considering the measurement’s uncertainty, including the uncertainty of the ratio of the activity concentration of the difficult to measure nuclide to that of the key nuclide. The key issues for the treatment of these uncertainty were summarized.

NRA Secretariat experts developed an empirical method for estimating source vicinity ground-motion levels on hard bedrock and annual exceedance probabilities for inland crustal earthquakes with sources difficult to identify in advance.

NRA conducted tube burst tests and post-test analyses on high-burnup spent nuclear fuel claddings to investigate the condition for the occurrence of macroscopic hydrogen-induced ductile-brittle transition at operational temperatures with quantitative consideration of precipitated Zr hydrides' morphology.

We have developed a debris bed formation prediction method that takes into account accident scenarios and physical properties by providing THERMOS with the analysis results in MELCOR.

Uranium is an important nuclear material and contaminant with respect to the sites of uranium mining and whole nuclear facilities.

A new risk-informed and performance-based inspection program will be enacted from April 2020. A part of this program builds on the information obtained from a probabilistic risk assessment (PRA).

The seawall is one of the main coastal protection structures against tsunamis. Estimating tsunami wave pressures on a structure is quite important when designing seawalls.