The Ministry of Economy, Trade and Industry said Kansai Electric Power Company and trading company Sumitomo Corporation were expected to sign a long-term agreement on the project with Kazakh state-run Kazatomprom in Astana, the former Kazakh capital, on Wednesday.
Experts attribute the companies' plans for a contract with the Central Asian country, which possesses at least a quarter of the world's uranium, to the need to diverse energy sources in the face of soaring world oil prices.
The Japanese partners are to provide technology and overhaul a Soviet-era nuclear processing plant in the Central Asian country.
The companies are set to allocate 70-80 billion yen (some $750 million) for the project, and the ministry said investment in expanding uranium production could reach several hundred billion yen, or several billion dollars.
Nuclear power makes up 30% of Japan's energy output, and the country intends to raise the figure to 40% by 2030, making nuclear power its key energy source.