This is the lower third of a cover to be erected over Fukushima Daiichi 1, pictured yesterday during trial assembly.
With a lightweight construction compared to the thick reinforced concrete of a reactor building, it will form a seal around the damaged building and reduce any ongoing emission of radioactivity and protect the building from the weather.
The top section of unit 1's reactor building was wrecked by a hydrogen explosion, the first at the site, on 12 March. The top structure had covered the service area above the concrete reactor containment, including the used fuel pond, which has now been visually inspected and found to have suffered no serious damage. An increase in radioactivity of pond water is not thought to have resulted from fuel damage due to overheating, but rather from the influx of contaminated dust after the explosion.
In the last three days the fuel pond's normal systems have been brought back into action to maintain water levels. The current temperature is not known, but sufficient water will maintain essential nuclear safety by preventing fuel damage. Cooling is to be restored by the end of this month through the use of an additional system.
According to Tokyo Electric Power Company's schedule, the cover should be completed in place by the end of September. It will be able to handle accumulated snow loads of 30 centimetres and wind speeds of up to 90 kilometres per hour.
All the wall panels will have a flameproof coating, and the structure will have a filtered ventilation system capable of handling 10,000 cubic metres per hour through six lines, including two backup lines. The cover structure will also be fitted with internal monitoring cameras, radiation and hydrogen detectors, thermometers and a pipe for water injection.
Similar cover buildings will be designed to fit around the other three damaged reactor buildings.
Researched and written
by World Nuclear News