16 May Last Rig Removed from DR 3

On May 15th, DD celebrated a significant internal milestone with the removal of the last rig from DR 3. This marked a historic day for the technical team, who operated the lead-lined horizontal transport flask for the final time.

TTuesday, May 15th, marked a day of internal celebration for DD. DR 3 successfully completed the removal of rigs (tubes) from the reactor when the last irradiation tube from horizontal silicon was extracted from the research reactor.

Just a few years ago, the reactor was surrounded by a multitude of auxiliary systems, such as ventilation and cooling systems, and remnants from experimental setups, including the silicon doping facility. Since the characterization (assessment of radioactivity levels, etc.) of the reactor in 2003, rigs have also been stored in the reactor's horizontal and vertical experimental holes. Over the past few years, pipes, systems, and equipment have been removed one by one by DD's research technicians and experimental assistants, leaving the reactor now quite bare.

The rigs are radioactive, having been exposed to radiation during operation. Their extraction, therefore, involves the use of a transport flask, which is lead-lined and effectively shields the surroundings from radiation.

The extraction process is somewhat complex, primarily due to the need to maneuver the 23.8-ton lead flask into position within confined spaces using the facility's large polar crane. Additionally, the operation involving the attachment of a “bridge” between the reactor and the flask, as well as the flask itself, must be executed swiftly and accurately to minimize personnel exposure to unnecessary radiation.

Fortunately, DD's technical personnel are well-versed in the operational procedures from the plant's active period, during which both vertical and horizontal transport flasks were frequently utilized for moving equipment, fuel, and experimental tubes. This particular operation, however, marked the final deployment of the horizontal flask at the facility, making today's successful execution a historic milestone for the technical team. The flask, containing the last rig, was safely transferred from DR 3 to the AH hall, where the rig is now temporarily stored in a concrete-lined storage facility hole.

The next steps in the dismantling of DR 3 are the dismantling of the heavy water space, which will begin in June 2012. In addition, the top void on top of the reactor must be cleared to masterplan, so that it is ready for the dismantling of the internal parts of the reactor.