information about Fukushima published in English in Japanese media info publiée en anglais dans la presse japonaise
3 Décembre 2013
December 3, 2013
http://ajw.asahi.com/article/behind_news/social_affairs/AJ201312030046
Stockpiles of unprocessed plutonium solutions and liquid waste at a nuclear reprocessing facility in Tokai, Ibaraki Prefecture, could boil and spew radioactive substances or cause hydrogen explosions if safety devices were to fail, the Nuclear Regulation Authority says.
The assessment of the Tokai Reprocessing Plant of the Japan Atomic Energy Agency, where 3.5 cubic meters of solutions containing plutonium and the 430 cubic meters of high-level radioactive liquid waste are stored, was part of a Dec. 2 report issued by the NRA.
The reprocessing plant extracts plutonium from spent nuclear fuel for use in plutonium-uranium mixed-oxide fuel for consumption in the Monju prototype fast breeder reactor and other facilities.
The plutonium solutions are supposed to be processed into mixed-oxide powder before going into storage, whereas the high-level radioactive liquid waste is supposed to be vitrified before going into storage. But the processing equipment for those operations has remained offline since 2007, partly because of anti-seismic retrofitting and partly due to equipment glitches.
NRA investigations showed that a loss of cooling functions could allow the liquid waste to boil and spew radioactive substances in 55 hours, while plutonium solutions could boil in 23 hours.
A loss of hydrogen removal functions could cause an explosion of hydrogen generated by the radiolysis of water in the liquid waste in 38 hours and a similar hydrogen explosion in the plutonium solutions in 11 hours, the NRA added.
The JAEA plans to take 18 months to process the plutonium solutions into 640 kilograms of mixed-oxide powder and 20 years to process the high-level radioactive liquid waste into 630 vitrified products.
The processing equipment can be restarted only after clearing the government's new regulatory guidelines, which are expected to take effect Dec. 18.
In view of the risk involved in leaving the liquid waste unprocessed, however, the JAEA has requested a special exemption to allow the agency to operate the equipment even before it passes the safety screenings.
The NRA is expected to review the request.
/https%3A%2F%2Fassets.over-blog.com%2Ft%2Fcedistic%2Fcamera.png)
/image%2F1225368%2F20190309%2Fob_2ace02_1000-water-tanks.jpg)
/image%2F1225368%2F20190307%2Fob_afc703_fukuleaks-report.jpg)