Heightened discharges as pump truck arrives
22 March 2011
Researched and written by World Nuclear News
ORIGINALLY PUBLISHED: 1.08pm GMT
UPDATE 1: 4.01pm GMT, Connection of power to unit 3
Discharges to sea from Fukushima Daiichi have shown increased levels of radioactivity, Tepco has reported, as it brings in a concrete pumping truck to secure water levels in used fuel ponds.
Tokyo Electric Power Company released the results of a half-litre sample of water taken 100 metres south of the discharge channel from damaged units 1 to 4.
Testing for a range of radionuclides showed amounts below regulatory limits for cobalt-58, iodine-132 and cesium-136. Detections were far above limits, however, for cesium-137, cesium-134 and iodine-131.
Local people began evacuation more than ten days ago and this is complete to a 20 kilometre radius. People in a further ten-kilometre zone have been warned to stay indoors. Pills to block the potential negative health effects of iodine-131 have been distributed to evacuation centers.
Iodine-131 has a half-life of eight days, so its potential danger reduces relatively quickly. Caesium-137 has a half life of 30 years, whereas the other isotope, caesium-134, has a half-life of two years. Additional monitoring at eight locations is to be carried out by the Japan Agency for Marine-Earth Science and Technology in conjunction with the Japan Atomic Energy Agency. Results from this are expected on 24 March.
Major pump begins work
At 5.17pm today efforts to refill fuel ponds at units 3 and 4 were upgraded significantly by the arrival of a concrete pumping truck of the kind usually used in construction. It will supply water at up to 160 tonnes per hour through a 58 metre flexible boom via remote control.
It is hoped that this extra reach, capacity and flexibility will enable Tepco to reduce issue of fuel pond levels and cooling until such time that normal systems can be brought back into operation.
External power connections have been made to units 1 and 2 and checks are underway to verify that systems will function when power is restored. A connection has been made for units 3 and 4 and cabling to the main power control centre has been completed.
White smoke was seen rising from the broken reactor buildings of units 2 and 3 yesterday, causing a short-term evacuation of workers from around unit 3 to a safer area of the site.
Smoke at unit 2 has now reduced virtually to the point of invisibility, while at unit 3 it changed from grey to white and is dissipating. Tepco said that neither its monitoring of unit 3’s reactor system or radiation in the area showed nothing unusual.