Drill confirms three-hour time delay for seawater injection

13 October 2011

The Fukushima Daiichi site completed an emergency cooling water drill on 12 October, its first since the 11 March earthquake and tsunami.

Firefighters uncoil hose for seawater injection drill
Firefighters uncoil hose for seawater injection drill


In the event of a magnitude 8 earthquake should knock out equipment on site, TEPCO said it could restart seawater injection at units 1-3 in about three hours, according to a report from Japanese news agency NHK published on the website of the Japan Atomic Industrial Forum. In the drill, 40 firefighters attached 300m of hoses from a seawater intake to truck-mounted mock headers via a fire truck.

In other news, TEPCO purged the containment cooling system of hydrogen by injecting 9m3 of nitrogen gas. On 28 September, the hydrogen concentration was measured to be 64%; half an hour after the gas injection the concentration was 4%. TEPCO said that the possibility of hydrogen explosion is very low because of the low (0.4%) concentration of oxygen.

The Japanese Ministry of Agriculture has published advice about how to decontaminate farmland affected by Fukushima Daiichi following tests in Iitate village and Kawamata Town in Fukushima province, according to Japan Atomic Information Forum's Atoms in Japan news service.

For land contaminated with caesium at levels of less than 5000 Bq/kg, the limit for rice farming, the report advises turning or burying topsoil as necessary to reduce the uptake of radiation to crops, and to reduce airborne radiation.

For land with caesium levels between 5000-10,000 Bq/kg, the report advises several different methods: agitating the topsoil, removing it by water, scraping it off, turning it or burying it, depending on the type of land and the soil condition.

For land with caesium levels between 10,000-25,000 Bq/kg, the report says that turning or burying the soil does not sufficiently dilute the soil, and therefore advises scraping off the topsoil.

For land with caesium levels above 25,000 Bq/kg, the report recommends scraping off the top 5 cm of soil after the soil has been treated (such as with chemical solidification) to prevent scattering dust.

According to JAIF, research continues on sunflowers and amaranth, which may take up caesium at higher rates than other plants.

In late September, Japan's nuclear accidents minister Goshi Hosono said that the government would present its plans for an interim radioactive waste storage facility by the end of October, according to Atoms in Japan. He said that the government would “not be able to carry out decontamination work on a broad scale without a centralized interim facility or facilities where the waste could be stored and

managed.”




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