The removal of a 50-tonne concrete and steel plug has allowed access to the containment of the UK's prototype steam generating heavy water reactor (SGHWR) for the first time since it was built in the 1960s.
|SGHWR's concrete plug is removed after 50 years (Image: RSRL)
The plug covered an access point used to install large plant items inside the reactor's concrete containment shell during the plant's construction. On completion of the installation, the access point was sealed with the reinforced concrete and steel slab which was then secured to the containment itself.
The project to decommission the reactor, which began in 1991, has now reached the stage where those large items of plant can be removed from the primary containment necessitating the removal of the plug for the first time. Some essential equipment and walkways had to be repositioned or removed to allow the plug to be extracted. After removing the securing bolts, trial lifts were carried out using a weight sensor to ensure that plant and equipment would not be overloaded.
The plug was successfully lifted clear of the containment and placed into storage, and has been replaced with a horizontal roller shutter door to seal the access point and act as a fire barrier. Work has now begun to remove the equipment from inside the primary containment.
The 100 MWe SGHWR is one of two reactors still undergoing decommissioning at the Winfrith nuclear research site in Dorset. Operating from 1968 until 1990, the prototype reactor supplied electricity to the grid as well as performing its prime function of supporting research into water-cooled reactor technology. Site licence company Research Sites Restoration Ltd recently announced a tender for a £40-60 million ($66-100 million) project to design, test and build specialist equipment to remove the remaining core components from the SGHWR.
Researched and written
by World Nuclear News