Successful Hot Operation of the German Vitrification Plant VEK - Results and Experiences - Paper 11277

The German VEK project has been established to vitrify approx. 55 m³ of high-level liquid waste (HLLW) with a total radioactive inventory of 7.7E+17 Bq in the new VEK vitrification plant erected from 1999 to 2004. Immobilization of the waste solution stored at the site of the former German WAK pilot reprocessing facility is the precursor to further decommissioning and dismantling of the WAK facilities which have been underway since the mid-nineties. Within a minimum operation period of only 9 months from September 2009 until June 2010 the highly noble metals containing HLLW was successfully processed and the storage tanks of WAK were finally emptied. Subsequent to hot vitrification of the concentrated HLLW solution an extensive cleaning of the storage tanks and VEK plant components is being performed. Rinsing liquids are being vitrified after mixing with simulated inactive HLLW solutions. The efficiency of the melting process performance with respect to noble metals was optimized by application of air bubbling subsequent to a complete waste glass exchange after the first six months of hot operation. In total nearly 500 kg of noble metals (in terms of oxides) were processed. The overall plant availability was in the range of 97% with only short lasting HLLW feeding interruptions caused by mainly remote exchange and cleaning of the off-gas-pipe, rinsing of the wet off-gas-line, leakage of a cooling water hose, melter emptying and insertion of an air bubbling device due to a suspected emerging of noble metal sediments. From processing of the waste solution actually 140 glass canister of the European standard type have been produced containing 400 kg waste glass with a waste oxide loading of 15 - 16wt.%. The glass canisters will be transported by CASTOR casks to the interim storage facility. This paper gives an overview of the successful hot operation of the VEK plant. Operational data, results and lessons learned during one year of hot operation are presented in detail.