Report on Japan's nuclear introduction experience

In the aftermath of World War II, Japan's electric power generation infrastructure was in a desperate condition. As the post-war economic recovery got under way, spurring demand for electricity, there was an urgent need to establish large power plants. In view of the country's paucity of natural resources, Japan promoted large scale development of hydroelectric power generation, but this was incapable of satisfying the demand for electricity. Therefore, Japan initiated a study with a view to introducing commercial nuclear power in step with the international trend toward the peaceful use of nuclear power. As a result of the study, it was decided to select the gas cooled reactor (GCR) using natural uranium fuel from the United Kingdom. This decision was based on accumulated experience of GCR operation and the fact that it was relatively easy to procure natural uranium fuel compared with enriched uranium fuel at that time. The start of operation of the GCR reactor (166 MW(e)) of the Tokai power plant unit 1 in 1966 signalled the dawn of the era of commercial nuclear power in Japan. At about the same time, the light water reactor (LWR) with low enriched uranium fuel was commercialized in the USA. It was decided that the second reactor to be imported would be the LWR because it had become possible to procure low enriched uranium and there was a prospect of scaling up plants in the future with relative ease. Following the second reactor, the LWR, the boiling water reactor (BWR) and the pressurized water reactor (PWR) introduced from the USA started operation around 1970. Reflecting the fact that nuclear power generation in Japan started shortly after its commercialization in various other advanced countries, there were cases in which nuclear power plants in Japan experienced a decline in their availability factors due to unknown problems and the workers dealing with these problems were exposed to high doses of radiation. From this experience, the importance of ensuring stable operation by improving the existing LWR was recognized. In these circumstances, the first LWR improvement and standardization programme was launched in 1975 for the purpose of achieving enhancement of reliability and a high availability factor and radiation dose reduction for workers, utilizing domestic technologies capitalizing on the experience of LWR construction, operation and maintenance. The results of the improvement and standardization programme were applied to the nuclear power plants that started operation from the 1980s onward. These reactors are still operating well. The objectives of the third improvement and standardization programme, launched in 1981, were long operating cycle, further improvement of core performance, compact plant and reduction of the construction period. The programme also envisaged development of the advanced boiling water reactor (ABWR) and the advanced pressurized water reactor (APWR). The world's first ABWR started operation in Japan in 1996, and four units of ABWR are in operation as of 2007. Regarding the APWR, the review process regarding the granting of an installation licence is currently under way and it is envisaged that the first unit will start operation around 2016. As of 2007, 55 LWR units are in operation in Japan. The first imported GCR using natural uranium fuel contributed to the development of nuclear power generation technology and the cultivation of human resources. The GCR, having demonstrated the commercial use of nuclear power, was shut down in 1998. The decommissioning and waste treatment for the GCR, which are under way, will be used to establish the technologies and procedures for future LWR decommissioning and waste treatment