|Rokkasho (Image: JNFL
The long-delayed reprocessing plant at Rokkasho-mura in Japan has passed a significant commissioning milestone, proving its vitrification lines and moving it towards operation.
A test completed this week successfully trapped highly radioactive materials from 70 litres of liquid waste within 25 glass 'logs'. This test of the 'A' vitrification line follows a similar successful trial at the 'B' line in January and completes an active test run of the entire reprocessing plant that began in January 2008.
Vitrification is the end of the reprocessing operation, which starts with the input of used reactor fuel. This is chopped up and dissolved in acid before the resulting liquor is chemically processed to recover reusable uranium and plutonium. This mix is kept for recycling into new reactor fuel, while the waste liquor goes to vitrification. In the resulting glass form, the wastes are ready for long-term storage and permanent disposal at much smaller volume than the original reactor fuel.
The Rokkasho plant took 13 years to build and its commissioning since 2006 has been extremely slow. Serious delays followed an incident when ceiling bricks in the glass furnace fell down, causing molten glass containing waste to stick on some surfaces.
The plant is owned and operated by Japan Nuclear Fuels Ltd (JNFL), which designed the vitrification unit to go with the reprocessing section supplied by Areva. JNFL needs to secure a licence from the Nuclear Regulation Authority before putting Rokkasho to work on reprocessing Japan's national stockpiles of used reactor fuel, currently slated to begin in October. Despite the uncertainty over nuclear power's future in Japan, the country's waste management policy remains centred on reprocessing before underground disposal.
Researched and written
by World Nuclear News