Tokyo Electric Power Co. said Thursday a system that can substantially reduce radioactive substances in tainted water at the Fukushima No. 1 nuclear plant has been halted because of a worker’s operational mistake.
The advanced liquid processing system, or ALPS, had been in continuous operation since it was switched on for a test run starting Saturday.
The equipment was halted at around 5:25 a.m. Thursday after the worker pushed the wrong button.
As no problem was found, the plant started discharging water from the ALPS at around 6:35 a.m.
Tepco is depending on the system to drastically cut the levels of 62 types of radioactive materials in water, excluding tritium.
On Wednesday, Tepco announced that an alarm went off at the crippled plant to warn that a dust monitor near the main gate had detected radioactive materials above an acceptable level in the air.
The utility said the incident was probably the result of an equipment malfunction because there were no major changes in radiation levels around the monitor and no problems with the reactors’ water injection and cooling systems.
According to Tepco, the alarm sounded around 3:55 p.m., warning that radioactive materials were detected above the set level of 0.0001 becquerel per cubic centimeter.
Dust monitors in other places and at monitoring posts showed no abnormalities, but Tepco issued a temporary order for workers at the plant to wear full face masks, including in zones where they are allowed to work without a mask.
No abnormal figures were found when radiation levels around the main gate were measured using a portable dust monitor, Tepco said.
Tepco also revealed Wednesday that it did not make public that dust monitor alarms sounded four times at the plant between November 2011 and November 2012. In each case, measuring equipment stopped showing abnormal readings after being reset.
A Tepco official said the company decided to announce the latest alarm activation after the power outage at the plant in March.
Aomori fuel processors face regulatory delay
The Nuclear Regulation Authority will not allow nuclear fuel-related facilities in Aomori Prefecture to operate before new regulatory standards are compiled, its chairman, Shunichi Tanaka, said Wednesday.
The new standards are expected to be implemented in December, according to the regulatory body.
This conflicts with Japan Nuclear Fuel Ltd.’s plan to launch its spent-fuel recycling facility to extract plutonium and uranium in the village of Rokkasho in October.
Recyclable-Fuel Storage Co., a joint firm between Tokyo Electric Power Co. and Japan Atomic Power Co., is also planning to open a temporary storage facility for spent fuel in the city of Mutsu in October.
The NRA intends to examine the facilities using the new regulatory standards before deciding whether to permit them to operate.
Suspected active faults in those areas have already cast serious doubt on the facilities’ viability.