Japan has asked Russia to send a floating radiation treatment plant, used to decommission nuclear submarines, which will solidify contaminated liquid waste from the country's crippled nuclear power plant.

Engineers at the Fukushima Daiichi nuclear plant have been forced to release radioactive water into the sea until Friday and have resorted to desperate measures to contain the damage, such as using bath salts as a dye to try to locate the source of leaks at the complex 240 km (150 miles) north of Tokyo.

More than three weeks after a 9.0 magnitude earthquake and massive tsunami hit northeast Japan and damaged the plant, engineers are no closer to regaining control of the facility or stopping radioactive leaks.

Operator Tokyo Electric Power Co (TEPCO) said on Tuesday, April 5, it started paying "condolence money" to local governments to aid people evacuated from around its stricken plant or affected by the radiation crisis, Reuters reports.

TEPCO is facing a huge compensation bill, but said it must first assess the extent of damage before paying compensation.

The world's costliest natural disaster has caused power blackouts and cuts to supply chains, threatening Japan's economic growth and the yen, and the operations of global firms from semiconductor makers to shipbuilders.

The quake and tsunami left nearly 28,000 people dead or missing, thousands homeless and Japan's northeast coast a wreck.