Explosive concentrations of gas at Fukushima Unit 1? Hydrogen and Krypton-85 levels fluctuating since April, says Tepco

Published: October 26th, 2012 at 11:57 pm ET
By ENENews

Status of TEPCO’s Nuclear Power Stations after the Tohoku-Chihou-Taiheiyou-Oki Earthquake (Daily Report as of 3:00 PM, October 23)
Source: TEPCO : Press Release
Date: Oct 23, 2012
Emphasis Added

At 9:37 AM on October 23, continuous nitrogen injection into Unit 1 suppression chamber was started. The nitrogen injection is planned to be continued for about a month until the hydrogen concentration in the suppression chamber is reduced to approx. 2%.

SimplyInfo: “This indicates that the current known level in the torus air gap is over 2% air density. 4% is the point where an explosion becomes possible.”

Mainichi: There is a danger of a hydrogen explosion if hydrogen levels reach 4% with more than 5% oxygen

Title: Progress Status of Mid-and-long Term Roadmap towards the Decommissioning of Units 1-4 of TEPCO Fukushima Daiichi Nuclear Power Station (Outline)
Source: Nuclear Emergency Response Headquarters, Government-TEPCO Mid-and-long Term Response Council, Working Council
Date: August 27, 2012
(Provisional translation)

Nitrogen injection to Unit 1 suppression chamber

As hydrogen concentration and Kr-85 radioactivity density have been changing since April, it is assumed that the hydrogen generated in the early stage of the accident and Kr-85 which remain in the upper part of the suppression chamber are intermittently released into the dry well. In order to investigate whether or not hydrogen and Kr-85 still remain in the suppression chamber, changes in hydrogen concentration and Kr-85 radioactivity density will be measured after injecting nitrogen into the suppression chamber (Early September).

Watch a Japanese television broadcast on the hydrogen levels at Unit 1 here

Published: October 26th, 2012 at 11:57 pm ET By ENENews