Steam spotted at Fukushima Daiichi Unit 3 - July 18, 2013

During the daylight hours in Japan on July 18, a contractor working on the roof of Unit 3 at Tokyo Electric Power Company's devastated Fukushima Daiichi nuclear station spotted steam coming up from the debris on the roof of the building --- which is formerly the operating floor and in normal conditions would not be open to the atmosphere, having been daylighted by the hydrogen gas explosion which occurred during the accident progression.

This event - the spotting and videotaping of the steam - has led to an overnight flurry of press reports on the situation, which are piggybacking on the recent announcements that contaminated water at relatively high activity levels is being found on the site grounds again, making for a cycle of worsening press for the struggling plant owner.

Representatives of TEPCO have stated to the press that it is likely that heavy rainfall in the area has led to rainwater pooling, moving and coming into contact with the primary containment vessel --- which some news sources are confusing with the reactor vessel, which is contained inside of the primary containment vessel.  The exact source is not known but TEPCO continues to investigate.

TEPCO has been continuously measuring xenon gas level (to monitor recriticality) and there is no spike.  Radiation levels on top of the reactor building are unchanged.  Cooling water flow has not been altered.  Temperatures at all points have not changed.  In other words, there has been no sudden change in the status of the damaged reactor that would explain a sudden increase of gaseous emission.  The logical conclusion then is that the steam is coming from somewhere else; water contact on the outside of the relatively hot PCV is as good a bet as any at this point.

The press overnight has been sporadic on the topic, mainly having been printed in Asia, but English language sources are beginning to pick up the story and run with it; this is why I've chosen to make an update on the topic today -- to bolster APR readers against the flurry of guesswork likely to appear later on today should this story gain traction. 

Here are some links of interest.

Times Live:  Steam Spotted at Fukushima Nuclear Plant

Asahi Shimbun:  Steam Rising from Reactor Building in Fukushima

TEPCO's latest press release on the subject of July 18 steam emission.  Includes a link to video (Japanese language labeled only) page which will show the video taken by the contractor.  Not playable on all platforms (especially mobile.)

Fuku-ichi Live Camera.  This video camera has been moved several times since the accident and is now back on the Unit 4 side.  Steam was not seen in this view, but close up by a contractor.  Not playable on all platforms.

As always, I continue to monitor the situation at Fukushima Daiichi, and if anything newsworthy happens you'll see it here.

8:30 AM Eastern  7/18
ATOMIC POWER REVIEW