The leak occurred Thursday, October 25th, on a service road during routine transportation from one part of the Mayak facility to another, it said. An unspecified problem with a hermetically-sealed valve on a cistern containing the material caused the spillage of liquid medium-grade radioactive waste.

The leak occurred after the waste had been transported from chemical-metallurgical facility No. 20, which during Soviet times separated weapons grade plutonium into metal content for the preparation of the charge in atomic bombs.

The number 20 plant ran several workshops and departments – among them a chemical department, a metallurgical department, and a mechanical foundry workshop. The last stage of production, the mechanical foundry workshop, was the last step in forging atomic bombs, and was therefore the most shrouded in secrecy. Goings-on at plant No. 20 remain classified today, and it is unclear what the plant’s function is.

Officials say the transport of the liquid waste was carried out in agreement with all procedures.

“The transport occurred in accord with all regulated conditions for the specialised cisterns, which have a sanitary and epidemiological qualification. The formation of spot radioactive contamination occurred during transport. The positive results for the contamination along a service road were established as a compromise to the hermetically-sealed valves of the cisterns by mid-level radioactive waste,” a Mayak spokesman told the state run ITAR-TASS Russian newswire.

Mayak said that efforts to deactivate the contamination on the service road were carried out effectively, and that Geiger counter surveys were conducted at all exits from the industrial complex.

“Contamination of transport leaving the industrial complex, including busses or personnel, has not been established. There are no casualties. A commission has been formed to investigate the technical breach,” Mayak’s press service told Bellona Web.

A history of accidents
In June 2007, a serious leak occurred at Mayak, which, according to various sources, cost plant Director Vitaly Sadovnikov his post. An accident on the pipeline for carrying pulps of radioactive solutions occurred over a two-day period from June 24th to June 26th in workshop No. 5 of Mayak’s plant No. 235.

In 2003, the license for Mayak radiochemical plant, No. 235, was yanked by Russia’s former nuclear safety oversight body, Gosatomnadzor, because the plant continued dumping radioactive waste in the Techa River Cascade on a temporary order issued during a time when the status of these reservoirs was not defined. The license was returned only when Rosatom’s precursor Minatom and the Mayak administration developed a program to address the combine’s technical and environmental shortcomings.

As a major Soviet nuclear weapons facility, Mayak 50 years ago suffered a catastrophic explosion at a waste tank, contaminating a large area and prompting authorities to evacuate 10,000 residents from neighboring regions.

The impact on the local population remains largely unknown, and environmental activists say the damage has been compounded by other accidents, leaks and planned discharges of liquid waste.