Twenty liters of water containing radioactive materials were accidentally released at a spent nuclear fuel reprocessing plant in the village of Rokkasho, Aomori Prefecture, earlier this week, operator Japan Nuclear Fuel Ltd. has said.

The water was released during an inspection of pumps in the purification system at a spent fuel pool in the Rokkasho complex, the nuclear power reprocessing company revealed Tuesday. The firm gave assurances, however, that the level of radioactive materials in the water was within the limits specified by government safety standards and would have had no impact on the employees' health.

According to the company, which is based in the prefecture, the water leaked onto the ground near the spent fuel pool at around 2:25 p.m. Monday, when nine workers from an affiliated company disassembled parts of the pumps for inspection after draining the pool. Water from the pool had remained inside the pump parts.

As the workers cleaned the floor soon afterward, the release did not impact other areas, the firm said.

Japan Nuclear Fuel said they were investigating the cause of the release, and that they would do their utmost to prevent any reoccurrence of such incidents in the future.