Cesium-137 flow into sea 30 times greater than stated by TEPCO: report
PARIS (Kyodo) — The amount of radioactive cesium-137 that flowed into the Pacific after the start of Japan’s nuclear crisis was probably nearly 30 times the amount stated by Tokyo Electric Power Co. in May, according to a recent report by a French research institute.
The Institute for Radiological Protection and Nuclear Safety said the amount of the isotope that flowed into the ocean from the Fukushima Daiichi nuclear plant between March 21 and mid-July reached an estimated 27.1 quadrillion becquerels. A quadrillion is equivalent to 1,000 trillion.
Of the amount, 82 percent had flowed into the sea by April 8, according to the study, which noted that the amount released as a result of the disaster triggered by the March 11 earthquake and tsunami was unprecedented.
The report also said the Pacific was polluted at an exceptional speed because the plant stands in a coastal area with strong currents, though it said the impact of the contamination on marine life in remote waters is likely to wane from autumn.
But the institute warned that a significant degree of pollution would remain in waters off the coast of Fukushima Prefecture, northeast of Tokyo. Radioactive cesium-137 has a half life of around 30 years.
(Mainichi Japan) October 29, 2011
Panel lowers limit of radiation in food
Experts quiz decision to ignore external exposure
Health minister Yoko Komiyama announced Friday that the government will lower the allowable amount of radiation in food products from 5 millisieverts per year to 1, but some experts are puzzled.
Permanent limits for various categories of food will be set based on recommendations submitted Thursday by the government’s food panel.
The current limit of 500 becquerels per kilogram of radiation for meat, fish and vegetables is also expected to be lowered by about one-fifth in April.
Citing findings from various studies, the food safety panel concluded Thursday that a cumulative dose of 100 millisieverts or more throughout one’s lifetime poses significant health risks.
But experts question the focus solely on internal exposure from food and drink, while ignoring external exposure from radioactive materials, such as fallout on the ground, roofs and in ditches.
“I can’t think of a reason why they decided to omit external exposure as a factor in the proposal this time,” said Dr. Eisuke Matsui, who heads the Gifu Environmental Medicine Research Institute.
The radiology expert noted that while consuming food contaminated with radiation is a far bigger risk to human health than being exposed to radiation from the environment, it does not mean it can be disregarded.
“Think of the children in the cities of Fukushima or Minamisoma, where there is a relatively high level of radiation in the environment,” Matsui said. “Any guideline on radiation should consider the total exposure and not only the limit of contaminated food one can consume.”
Article continues at:
Emergency press conference reveals 110 microsieverts per hour at Tokyo supermarket
TOKYO, Oct. 28 — Breaking news from Mochizuki, “110 micro Sv/h in Setagaya.”
“In Setagaya, Tokyo, ward mayor held an emergency press conference at 10PM,” says the report. They announced the 110 micro Sv/h near ‘Powerlarks Setagaya’ supermarket.
“If an average citizen measured it, it might be way higher,” notes Mochizuki.
Major Study: Reactor No. 5 releases may explain why so much radioactive xenon detected… or “recriticality has occurred in one of the reactor units”
SOURCE: Xenon-133 and caesium-137 releases into the atmosphere from the Fukushima Dai-ichi nuclear power plant, Stohl, A., Seibert, P., Wotawa, G., Arnold, D., Burkhart, J. F., Eckhardt, S., Tapia, C., Vargas, A., and Yasunari, T. J., October 20, 2011
“Fortunately, due to the maintenance outage and the survival of one diesel generator, it seems that unit 5 reactor cores as well as spent fuel ponds have not suffered major fuel damage,” says the study.
Though, Reactor No. 5 is mentioned again several pages later:
“Total a posteriori [experienced levels] 133Xe emissions are 16.7 EBq, one third more than the a priori value [predicted levels] of 12.6 EBq (which is equal to the estimated inventory) and 2.5 times the estimated Chernobyl source term of 6.5 EBq.”
If there was only 12.6 EBq of xenon-133 inventory that could be emitted from reactors 1-3 and spent fuel pool No. 4 — yet 16.7 EBq was experienced — where did the extra xenon come from, according to the study?
- “There is the possibility of additional releases from unit 5.”
- Another possibility is that recriticality has occurred in one of the reactor units.
The study says the a priori emissions could have been overestimated, but discounts the notion that the initial 12.6 EBq figure so poorly underestimated the amount of xenon in Reactors 1-3 and SFP 4, “It is unlikely that the 133Xe inventories of the reactor units 1–3 were one third higher than estimated.”
SOURCE: Discussion Paper
NOTE: ENENEWS.com also has this headline for the above research publication:
“High concentrations” of radiation hit US and Canada — Plume was rich in Cesium-137 and “close to the surface” from Vancouver southward — See also Hawaii, Florida (MAPS)