“Failure” of Voluntary Safety Efforts
Second is the “failure” of voluntary safety efforts by private nuclear utilities. Nuclear safety regulation in Japan has had a tendency toward relying heavily on operators' voluntary safety efforts. The current institutional design, where NISA is located under the Ministry of Economy, Trade and Industry (METI), has been well adapted to such attributes of regulation.
Though belatedly, Japan introduced its system for severe accident management in 1992. However, under the regulatory scheme of voluntary safety efforts, accident management measures were basically regarded as voluntary efforts to be made by operators, not legal requirements. Moreover, in Japan, it was decided in keeping with the intention of operators that the PSA(Probability Safety Assessment), which provides the basis for accident management, limit its scope to internal events, and exclude external events including earthquakes. These refl operators' concerns on gaining public acceptance in siting areas as well as technical challenges involved in evaluations of external events.
Voluntary measures for severe accident management, however, became subject to informal evaluation by the regulatory body in the periodic safety review (PSR), which is one of the quality assurance activities taken up by operators voluntarily every 10 years. Through this informal evaluation, severe accident management had gradually expanded its scope to include external events such as fires. We might say that such voluntary safety efforts were effective to a certain extent.
However, when NISA made the PSR obligatory as a requirement of operational safety regulations after some scandals involving TEPCO's cover-ups of cracks in shrouds in 2002, NISA left the PSA-related matters as voluntary requirements because of insufficient technical expertise to conduct PSAs. As a result, NISA no longer evaluated severe accident management informally, and the expansion of the scope of the PSA was halted. This can be regarded as an adverse effect of institutionalizing voluntary safety efforts.
Operators had taken voluntary measures against tsunami risks as well. It was the electricity industry that supported a series of studies by JSCE on tsunami assessment technologies as mentioned above. Power companies also showed their concern about the new simulation studies on the Jōgan tsunami, and tried to seek countermeasures by making contact with researchers on this project.
In the end, such voluntary efforts were too slow to prevent this accident caused by the earthquake and tsunami. In addition, the delay in accident responses is assumed to be due also to the circumstance that it was hard for the operator to vent voluntarily without the government's involvement. Considering these points, we must conclude that there have been some real limitations in the conventional methods of voluntary safety efforts.
This does not necessarily mean, however, that the offi regulation system by the regulatory body would be completely effective. As for the responses to tsunami risks, it was not the electricity industry but the regulatory body that should have commissioned the studies on tsunami assessment technologies by JSCE. The regulatory body has given less attention to recent fi in related fi than operators have.