Operation of the HLLW vitrification Mock-up Test Facility

After the mock-up test facility was constructed in March, 1982, the operational test runs were carried out from April to July, 1982. The operational results of pre-treatment and glass melting are described in this paper. The mock-up test facility is equipped with both batch denitration and continuous denitration vessels. The operational ability of the two types of denitration equipment was compared. In the batch denitration equipment, a liquid waste (1 m3) was denitrated with formic acid under reflux condition, and concentrated to a volume of 0.5 m3. In the continuous denitration, the feed rate of HLLW to the denitration vessel was adjusted by an air ejector system, and denitration proceeded under non-reflux condition. The concentration rate was controlled by the quantity of heating steam. The denitrated concentrate was transferred gravitationally to the melter. The glass melter of the mock-up test facility is a liquid-fed Joule-heated ceramic melter. Before the initiation of Joule-heating, the melter was heated by SiC resistance heaters. From the test results, it was concluded that 1) the denitration in batch process was safely controlled by the step-wise increase of HCOOH addition, 2) the gas evolution rate in continuous denitration process was very low and stable, but the clogging of over-flow line may occur when excessive HCOOH was added, and 3) the Joule-heated ceramic melter was operated successfully to yield homogeneous glass product. (Yoshitake, I.)