Experience With Operation of Mobile Cementation Facility at A-1 NPP

Abstract

The purpose of the paper is to describe a mobile cementation facility (MCF), which was designed by VUJE, Inc. and by JAVYS, Inc. (Nuclear and Decommissioning Company) in 2003. MCF was constructed and installed in 2004 in the so-called garden nearby A-1 NPP in Jaslovske Bohunice, where underground storage tanks for liquid radioactive waste are located. The facility is designed to process liquid radioactive waste and sludge or gravel collected from the underground tanks. These storage tanks are situated in the vicinity of active water treatment plant belonging to A-1 NPP. The tanks, some of which are of diameter 16 m, have their internal complex structure. All tanks were designed to collect various liquid waste streams from the A-1 NPP reactor building. Special remotely controlled DENAR 41 manipulator was developed. for the collection of liquid waste as well as for other purposes (collection of solid waste, decontamination, cutting of internal pipelines, etc.) The unique mobile equipment, which carries a suitable pump for sludge pumping to the cementation facility, was used to collect sludge last year. Large diameter of the storage tanks and small hatchways for the inspection access (approximately 540 × 540 mm) through which the telescopic mast of manipulator DENAR 41 or the special mobile vehicle were inserted into the tanks proved to pose some difficulties while being at use. Standard ISO containers, in which the main components are installed, were designed and used for the MCF project. The whole equipment is relatively easy to transport and can be installed to any other tanks with stored liquid waste. In-drum mixing technology is applied during cementation process. Standard 200 litre drums with the cement product are the only outputs form the mobile cementation facility. Production of 200 litre drums with the cemented product gradually increased from 19 pieces per year in 2005 to 88 pieces last year in 2008. Several problems particularly in the cement dosing system as well as problems in monitoring and measurement system with occasional failures in control system appeared amidst MCF operation. However these issues were always operatively resolved and the cementation facility could successfully met desired expectations.