Saturday, November 9, 2013

GE Boiling Water Reactors

Fukushima Unit 3 Log

Fukushima Unit 3 Log

In the latest photo, the shield plug appears intact, but if you look closely the center of the middle piece is depressed downward. TEPCO's analysis is that some heavy debris fell on top of the piece after the explosion, and the shield plug itself (which has three layers) is structurally sound. The shield plug is not likely to be touching the Containment Vessel head, says TEPCO in theaccompanying document.

Again from TEPCO's photos and videos library, 2/14/2014, photos of the shield plug, with the second photo showing the gap of 300 millimeters (or 30 centimeters):

Diagrams of the shield plug, and TEPCO's analysis on the deformed shield plug, from the accompanying document (Japanese):

(TEPCO's analysis above)
The cause of deformation could be "hydrogen explosion" or "falling of the ceiling crane and other objects". However, as the floor slab (30-centimeter and 60-centimeter thick) surrounding the shield plug is not damaged, it is not likely that the shield plug (made of three layers of ferroconcrete (60 centimeters each) was deformed by the hydrogen explosion. The ceiling crane itself did not make direct contact with the shield plug after it fell, but there was a trolley above the shield plug. So the deformation is likely to have been caused by the fall of the main hoisting hook onto the shield plug.

Video from above of cleared Unit 3 operating floor showing damaged reactor plug

For building precursor findings of Fukushima Daiichi Nuclear Power Station Unit 3 reactor building top debris removal after

PostedFebruary 14, 2014

via ex-SKF / December 29, 2013 /
(UPDATE 12/31/2013) For those who want the summary of the steam incident since July this year and the Reactor 3 operating floor condition since the March 2011 accident, I have a new post.
An acquaintance who casually follows the Fukushima I NPP accident sent me a link, quite worried. I opened the link, and I started laughing, then I despaired – realizing that this may be the current level of understanding in the US when it comes to the Fukushima I NPP accident.
I have no idea who this is (“Turner Radio Network – Free Speech, No Matter Who Doesn’t Like It”), but it has an urgent news flash on December 28, 2013:

Persons residing on the west coast of North America should IMMEDIATELY begin preparing for another possible onslaught of dangerous atmospheric radiation from the Fukushima nuclear disaster site in Japan. The Tokyo Electric Power Company (TEPCO) says radioactive steam has suddenly begun emanating from previously exploded nuclear reactor building #3 at the Fukuishima disaster site in Japan. TEPCO says they do not know why this is happening and cannot go into the building to see what’s happening due to damage and lethal radiation levels in that building. Experts say this could be the beginning of a “spent fuel pool criticality (meltdown)” …

The page shows a photograph of Reactor 3 steaming vigorously to lend support to the contention above.
The problem? It is a photo from March 2011 right after the building blew up.
Further down the post,
The video below was taken several months ago by TEPCO. It shows that the roof is totally blown off reactor building # 3

October 10, 2013:

Add caption

Overhead crane, and brown cover over spent fuel pool

July 2013 west wall nearly completed

Construction of outer building for Unit 3 between main building and turbine building

Everything above the fueling floor has been removed except the collapsed overhead crane

May 2013

May 25, 2013:

Feb 16, 2013 wreckage in pool #3

December 2012

Photo: Unit 3 spent fuel pool from above, with a portion of the liner protection system visible at its edges. Source: TEPCO.

Beam Removed from Unit 3 SFP
While clearing debris from around the unit 3 spent fuel pool on Sept. 22, a piece of remotely operated equipment dropped a steel beam into the water. TEPCO workers retrieved it Thursday, according to a release, after practice runs using a mockup of the beam and the SFP. Before the beam was lifted from the pool and set on the ground next to the reactor building, crews also lowered a system of rods and chains into the SFP to protect its liner during the procedure. A water purification system was also installed that TEPCO said doubled visibility in the pool to 5 meters. No damage to the liner or changes in plant conditions were detected after the beam was removed.

September 21, 2012 (SFP, when TEPCO started removing the debris):

July 11, 2012:

Video of spent fuel pool  - mostly wreckage
August 2011

Reactor 3 fuelled by Plutonium & Uranium mix oxide
Extensive radioactive steam coming from reactor core. Only the east vertical pillars remain standing, and even they are extenstively bent over.  West pillars are completely gone. Only part of the roof framework remains.  The picture below wasthe one that I marked up showing the upper left "spider hole" shaft used to lift fuel up from ground floor, sfp at lower left, dryer pool at lower right, center of reactor cover, and crane collapsed (two gray beams) onto the refueling floor.
Reactor No 3
Reactor No3
This is from the south looking north. The roof is at an angle as west wall is gone, but roof (but not crane) is supported on the east side. 

Unit 3 looking at the north side, looking south shows that the northwest (closest) corner was destroyed to one level below the top floor. The explosion not only blew out wall panels, but destroyed part of the floor and blew out the structural pillars on the northwest corner.