Chronic water seepage at Australia’s only nuclear reactor has sparked plans to build a plant to treat the water in a sign the problem might never be fixed.

The problem lies within the new Argentinian-built OPAL nuclear reactor used not to produce power, but rather nuclear medicines, neutrons for scientific research and irradiation services.

It seems water is seeping into “heavy water” which acts as a coolant in the process, Fairfax newspapers report.

The reactor, commissioned in 2006, is based at Lucas Heights south of Sydney and is managed by the Australian Nuclear Science and Technology Organisation (ANSTO).

The reactor has been out of operation for 11 of the past 14 months, during which time Australia has had to rely on costly imports from countries including South Africa.

The water seepage was first identified in December 2006 and attempts have been made to address the problem during an extended shutdown.

“This was only partially successful,” ANSTO told Fairfax.

“The seepage has been slowed by adjusting the pressure differential between the reflector vessel and the reactor pool.

“Several other options for mitigating or completely rectifying the seepage are being assessed and trialled in consultation with the designer … who are responsible for the rectification under warranty.”

ANSTO confirmed that a heavy water upgrade plant is an option being considered to address the seepage problem.