INNOVATIVE UNDERWATER CUTTING PROCEDURES FOR THE DISMANTLING OF TWO GERMAN NUCLEAR POWER PLANTS

摘要

The two power stations, KRB A and VAK, represent the first generation of Boiling WaterrnReactors in Germany. VAK (Versuchsatomkraftwerk Kahl), located in Kahl, near Frankfurt,rnwas Germany’s very first nuclear power plant and served mainly scientific purposes, whilernKRB A (Kernkraftwerk RWE-Bayernwerk, Block A), located in Gundremmingen, nearrnMunich, was Germany’s first commercial reactor.rnBoth plants are shut down and decommissioning is under way. Up to now more than 70 % ofrnthe systems have already been dismantled and decontaminated. In KRB A for instance aboutrn6,500 tons of contaminated material has been treated, allowing to recycle 93 % and leavingrnonly 7 % of radioactive waste for final storage.rnThe actual work in both projects is focused on dismantling the reactor pressure vessels and itsrninternal components. Besides extensive experiences in both plants with mechanical tools, likernsawing, shearing and grinding, two innovative cutting procedures are applied for this purpose,rni.e. plasma arc cutting and abrasive water suspension jet (AWSJ). The application of plasmarncutting in KRB A and AWSJ-technique in VAK has qualified these procedures as state-of-theartrnin the nuclear field.