November 23, 2018
The Japan Atomic Energy Agency said Wednesday that some of the low-level radioactive waste stored underground at a facility near Tokyo may leak from its containers due to inadequate disposal procedures.
The government-backed agency keeps 53,000 drums of low-level radioactive waste, or about 10,600 kiloliters, in a concrete pit in the basement of a building of the Nuclear Research and Science Institute in the village of Tokai, Ibaraki Prefecture.
Some of the waste did not undergo the proper water removal process when placed in the pit, and leakage and corroded containers in the pit were found during inspections between 1987 and 1991, according to the agency.
The nuclear research body planned to inspect the drums over the next 50 years to check for leakage. But the Nuclear Regulation Authority said at a meeting Wednesday that the agency needs to check them more quickly.
The agency should inspect all the drums within five years, Shinsuke Yamanaka, an NRA commissioner, said at the meeting.
The agency currently inspects the drums visually once a year but will now begin to lift and check them individually.
According to the agency and the NRA, the low-level radioactive waste is placed at the facility, built sometime from around 1964 to 1976, for disposal.
The agency said it did not properly conduct the process of removing water and other materials in some cases during the 1960s.
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The Tokai spent nuclear fuel reprocessing plant in Tokai, a village in Ibaraki Prefecture
TOKAI, Ibaraki Prefecture–Drums of nuclear waste are stacked in disarray within a storage pool containing unidentified floating objects. Wires in the pool are feared entangled, and containers are believed corroded, possibly leaking radioactive substances. And highly toxic liquid waste remains untreated in a potentially explosive state.
After years of apparent mismanagement, the Tokai spent nuclear fuel reprocessing plant is a jumbled mess, as the operator, Japan Atomic Energy Agency (JAEA), prepares for the Herculean task of shutting down the facility.
The circumstances at the plant in this village northeast of Tokyo has raised concerns about the JAEA’s ability to dismantle it.
“A situation far from appropriate has been allowed to continue at the plant,” said an official of the Nuclear Regulation Authority, the nation’s nuclear watchdog. “Not only the JAEA, but also the former Science and Technology Agency and the former Nuclear and Industrial Safety Agency, have all looked the other way despite their knowledge of the situation.”
According to a JAEA report submitted to the NRA on Nov. 30, it will take 70 years to complete the dismantling process, with costs estimated at 217 billion yen ($1.92 billion) for the first decade alone.
A recent visit to the plant by Asahi Shimbun reporters revealed drums containing radioactive waste stacked in a disorderly manner in a storage pool.
JAEA officials showed pictures of the pool and explained that it contains about 800 drums piled about 7 meters high. The drums hold demolished clads from spent nuclear fuel assemblies.
The officials said that when an underwater camera was placed near the drums, it stirred up brown objects.
“We have no idea if they are water scale or rust,” one of JAEA officials said.
Workers put the drums in the storage pool between 1977 and 1994 by hanging them with cables above the pool and then cutting the cables to allow them to drop in, according to the officials.
The officials said they believed the cables also fell into the pool and became entangled.
Some experts at the NRA suspect the drums are now corroded and leaking radioactive materials.
Radiation at the pool surface measured 3 millisieverts per hour, three times the safety limit for annual exposure for a person, apart from background radiation.
The pool is not equipped with purification units.
Furthermore, JAEA officials said they do not know what’s in other containers at the facility.
Workers will eventually sort them out by opening their lids, they added.
One of the most challenging tasks facing the JAEA in the dismantling work is dealing with the 400 cubic meters of high-level radioactive liquid waste at the plant.
The liquid waste, which was generated during reprocessing, emits radiation registering 1,500 sieverts per hour, which would kill a person exposed for 20 seconds.
Left intact, this waste could produce heat and hydrogen, possibly leading to hydrogen explosions.
The JAEA has put the liquid waste in six stainless tanks and kept them cool with water. A ventilation system has been used to prevent hydrogen from accumulating inside the storage facility and sparking an explosion.
Ibaraki Prefecture is located immediately south of Fukushima Prefecture.
The Great East Japan Earthquake and tsunami that struck northeastern Japan in 2011 severed all power sources to the Fukushima No. 1 nuclear power plant, leading to hydrogen explosions and the triple meltdown there.
The natural disaster also cut off electricity to the Tokai plant for more than 40 hours. But the plant rode out the contingency with emergency power generators.
The NRA is aware of risks involved in keeping the liquid waste in the current state at the Tokai plant.
In 2013, the NRA allowed the plant to resume operations to solidify the liquid waste with glass as a special case before the watchdog checked whether the plant met tougher nuclear safety regulations set after the Fukushima disaster.
Work on the solidification process resumed this year, but it has been suspended because of a series of glitches. Only one-fourth of the scheduled volume of the liquid waste has been solidified.
The reprocessing plant began full operations in 1981. It had reprocessed 1,140 tons of spent nuclear fuel before the decision was made in 2014 to close down the facility.