An experiment to convert radioactive liquid waste into an easier-to-dispose-of glassy substance at a spent nuclear fuel reprocessing plant has been delayed because preliminary work has been marred by trouble.
An experiment to convert radioactive liquid waste into an easier-to-dispose-of glassy substance at a spent nuclear fuel reprocessing plant has been delayed because preliminary work has been marred by trouble.
Japan Nuclear Fuel Ltd., operator of a spent nuclear fuel reprocessing plant in Rokkasho, Aomori Prefecture, said Feb. 3 that the experiment to vitrify highly radioactive liquid waste will be postponed to at least early March.
JNFL has not revised the goal of finishing the experiment in October, but that deadline is unlikely to be met, sources said.
The delay may influence discussions on reviewing the government's nuclear fuel cycle policy.
The trouble took place in a furnace where highly radioactive liquid waste, left after plutonium and uranium have been extracted from spent nuclear fuel rods, is mixed with melted glass.
In a rehearsal, imitation liquid waste that contained no radioactive substances was mixed with melted glass and was drained into a container from an outlet at the base of the furnace, but the drainage eventually became too slow. A rod was used to stir the mixture so that solid glass did not clog up the outlet, but the fluid did not regain its initial drainage speed. The operator stopped heating the furnace on Feb. 3.
The drainage jam could be attributed to the formation of a glass chunk in the furnace, JNFL officials said.
JNFL plans to insert a drill into the base of the furnace to scrape off any glass that might have stuck.
JNFL initially started a trial run on this procedure at the reprocessing plant in 2006, but suspended it in 2008 after a succession of troubles. The end date for the trial run has been postponed 18 times so far.
Preliminary work for a resumption started on Jan. 24, after a 10-month hiatus following the Great East Japan Earthquake. Experts were questioning the feasibility of the target end date even before the latest trouble was reported.
If the radioactive waste can be successfully vitrified, scientists say it can be disposed of by burying it or keeping it in a storehouse.