Volcano questions for Sendai restarts

13 May 2014

Additional work on protection against volcano eruption is complicating the process to restart two reactors at Sendai, while other Japanese reactor restarts await the result.  

The Nuclear Regulatory Authority (NRA) is working through submissions from seven power companies regarding 17 reactors they would like to operate once again for electricity generation. The NRA has prioritised the application for Sendai 1 and 2, owned by Kyushu Electric Power Company, as the new regulatory system is put to the test.

Kyushu's application has been under discussion with the NRA since it was submitted in July last year and the power company has already revised the paperwork once to give more information. It was told to do so again on 8 May to address some 42 points covered in the discussions but not sufficiently documented.

A separate issue exacerbating this slow progress is volcano protection. The Sendai plant is in Kagoshima prefecture in Japan's southern Kyushu island and situated about 60 kilometres from the active volcano Mount Sakurajima. The plant must therefore be prepared for eruption scenarios where heavy ash fall may compromise personnel, equipment, cooling water and grid power supply. However, the NRA is struggling to set clear requirements in this area and in April it told Kyushu to consult with volcanologists and devise extra safety measures beyond those it had already proposed.


Sendai 1 and 2 will be the first to go through the new regulatory system. Applications have also been made for Genkai 3 and 4; Ikata 3; Ohi 3 and 4; Takahama 3 and 4; Tomari 1, 2 and 3; Kashiwazaki Kariwa 6 and 7; Shimane 2; Onagawa 2 and Hamaoka 4.

At launch the regulatory process for restart was hoped to take about six months, but applications were submitted in July last year and it is not yet clear when Sendai, or other units, might restart.

Once the NRA is technically satisfied, it will allow four weeks for public comment. Then the utility must carry out a definitive list of design modifications, which NRA will inspect before restart is finally permitted. This whole process is not expected to be complete in time for Japan's peak electricity demand in July and August, meaning another spell where the balance of power supply and demand will be tight.

Researched and written
by World Nuclear News