8,000 accelerator facilities with their own regulations

May 29, 2013

Nuclear regulators to review radiation controlled areas at major accelerator facilities

http://mainichi.jp/english/english/newsselect/news/20130530p2a00m0na012000c.html

The Nuclear Regulation Authority (NRA) said on May 29 that it will check and review radiation controlled areas at major accelerator facilities similar to one of the Japan Atomic Energy Agency (JAEA)'s nuclear physics laboratories in Ibaraki Prefecture which released radioactive substances into the atmosphere last week.

The NRA also said it will look into the process in which the operators of such facilities have obtained approval for designating radiation controlled areas at their facilities. The NRA made the decision because the operator of the Japan Proton Accelerator Research Complex (J-PARC), one of the JAEA's nuclear physics laboratories, which accidentally released radioactive substances into the atmosphere last week, used a method of controlling radiation which did not take into account the possibility of radioactive contamination inside the accelerator building. The NRA plans to check the safety of dozens of large-scale accelerator facilities across the country and give instructions to review the way in which they set up radiation controlled areas if flaws are found. There are about 8,000 accelerator facilities throughout the country.

The Laws Concerning the Prevention from Radiation Hazards due to Radioisotopes and Others allow the operators of such facilities to set up two different radiation controlled areas -- a Class-1 controlled area and a Class-2 controlled area. The strict Class-1 controlled area is set up where there is a possibility of radioactive contamination and internal exposure to radiation. The Class-2 controlled area can be set up where there is no possibility of radioactive contamination.

At the "Hadron experimental facility," which released radioactive substances into the atmosphere last week, a Class-1 controlled area was set up only around the experimental apparatus, and dozens of people, including researchers, were exposed internally to leaked radiation in a Class-2 controlled area. It was a lax safety control area in which no filter for radioactive substances was attached to a ventilation fan, causing radioactive substances to escape into the outside atmosphere. According to J-PARC officials, people wore special long-sleeved clothes in the Class-1 controlled area and checked to see whether radioactive substances were adhered to them when leaving the area. But in the Class-2 controlled area, people wore ordinary work clothes and moved in and out of the area without checking on radiation.

Meanwhile, the National Institute of Advanced Industrial Science and Technology (AIST) in Ibaraki Prefecture and the National Institute of Radiological Sciences (NIRS) in Chiba Prefecture do not divide their facilities into two different radiation controlled areas. They, instead, put their facilities under a single controlled area where they assume radioactive contamination could occur anywhere in the area. The AIST says a filter is attached to a ventilation fan and there are in-house regulations on decontamination procedures.

The operators of such facilities decide which category of controlled area should be set up on their own and all they need to do is effectively report their decisions to the government. They can also decide on guidelines for setting up such controlled areas. Thus, their regulations are looser than the Nuclear Reactor Regulation Law that controls over nuclear reactors.