AP, Mar 27, 2015 (emphasis added): [It] was billed as a way to decipher where, exactly, the morass of nuclear fuel might sit at the bottom of reactors… But what went wrong, even in a simple demonstration for reporters… was a sobering reminder of the enormous challenges that lie ahead… a programming glitch could not be fixed in time for Friday’s demonstration… No one knows where the molten fuel debris lies, and in what shape or state. [TEPCO] has said itlikely sank to the bottom of the plant. But the fuel could have dropped even beyond. Tadashi Yotsuyanagi, an official in charge of the muon project at Toshiba… acknowledged the technology will not be able to get the complete image toward the bottom of the reactor… David Ireland, a professor who heads the Nuclear Physics Group at the University of Glasgow, said muons may be the only way to probe inside atomic reactors. “There are not really any other noninvasive options that will allow inspection,” he said in an email.
The Japan Times published the AP report above, however one sentence was altered. “Tepco has said it likely sank to the bottom of the plant. But the fuel could have dropped even beyond” vs. “But the fuel could possibly have escaped even beyond the containment facility to the outside environment.”
IAEA technical meeting Managing the Unexpected, Harri Tuomisto, Sr. Nuclear Safety Officer at Finland’s Fortum Power, 2012:
- Part 4: “If the cooling is not successful, it means the corium melts through the vessel… When this massive amount of corium enters into the containment zone, there are very, very many different energetic consequences… Interaction of molten core and concrete starts… concrete is eroding, and this eroding of concrete, for a long time it was known as China Syndrome.”
- Part 5: “The corium will be in 3 parts, there is a solid crust formation in the bottom of the pool, then there’s a pool of oxidic materials… The metals and oxides are not soluble with each other and the metals will be separated… which is bad news in the sense that theheat transfer to the vessel is much higher, and it’s much more difficult to guarantee the integrity of the [containment] vessel in that case.”
- Part 6: “Molten corium on the containment floor, it’s eroding the concrete and going partially downward. Actually it will never go to China, because it also erodes sideways… The final size of the pooling maximum case is 10 to 15 meters in diameter, and 6-7 meters [20-23 ft or 2 stories] deep — or even deeper.”
- Part 9: “There are quite many challenges… There are different energetic phenomenon… which can lead to different combustions… accelerating flames, or even detonations — which can cause a very high pressure in the containment and even break the containment… Then there’s this China Syndrome — attack of containment liner by corium — which can also bypass containment.” (See US gov’t analysis: Fukushima containment breached due to “failure of the drywell liner by melt-attack“)
- Slides 3-4: If corium melts through the vessel, there are various energetic consequences caused by ejected high-temperature molten corium… Molten corium on the containment basemat initiates core-concrete interaction that releases aerosols and non-condensible gases to containment atmosphere and erodes the concrete (‘China syndrome‘)
- IAEA Paper: Corium was not cooled in majority of tests using water injected from above, as done at Fukushima — Were studying how to stop molten core from melting through concrete December 26, 2013
- IAEA ***NOT for distribution***: Molten core is suspected to have penetrated Fukushima containment vessel — Prime Minister on 3/11: We couldn’t be in Tokyo if melted fuel went through containment vessel (VIDEO) December 18, 2013
- Nuclear Engineer: New video appears to show molten corium that melted out of Fukushima reactor — “Some of it is still oozing” — We’ve been talking about criticalities going on and causing continued heat for a long time now” (AUDIO & VIDEO) February 23, 2015
- Gov’t Doc.: Re-criticality a threat at Fukushima; Concern melted fuel to change it’s form — M.I.T. Q&A: Coolability of the molten corium is questionable (VIDEO) December 4, 2013
- Nuclear Expert: Disgusting that Fukushima’s corium hasn’t been located — If melted fuel burned to center of Earth it’d be nice, that gets rid of it — Impossible to retrieve all of it (AUDIO) September 28, 2013
Kyodo, Mar 27, 2015 (emphasis added): [Tepco] disclosed that a 35-ton piece of machinery debris might be resting on the inner gate of the spent fuel pool for reactor 3… and that the gate is slightly out of position. Tepco said Thursday that a fuel-handling machine… is
touching one of two gates that stand between the pool and the reactor containment vessel [and] both… gates are slightlyout of position but said the pool… does not appear to be leaking… If the gates are damaged, it might trigger a water leak from the pool…
The Japan Times changed the headline on Kyodo’s report from ‘Debris poses risk to spent-fuel pool gate in Fukushima No. 1′s reactor 3‘ to ‘Setback at Fukushima No. 1 plant threatens reactor 3 rod removal’.
NHK, Mar 27, 2015: Fuel pool gates found shifted at Fukushima plant… [TEPCO] says 2 iron gates that keep cooling water inside a spent fuel pool were found to be out of position… officials say this could affect the removal of debris… TEPCO officials said on Thursday that both of the iron gates in the pool hadshifted from their original positions. They say the innergate was likely damaged by a large machine that fell into the pool. The operator says it will examine if removal of the machine from the pool may trigger water leaks.
Enformable, June 2012: Nuclear engineer Chris Harris identified the “weakest link” which may initiate a spent fuel pool draindown… The gate is a long rectangular “dam” in the side of the fuel pool… The gate has seals so that the fuel pool doesn’t drain into the cavity and dangerously expose fuel assemblies… If the seal were to fail, then the fuel pool would drain to dangerously low levels right through the damaged gate.
Chris Harris, former licensed Senior Reactor Operator and engineer, Nov 2012: “One of the Tepco releases that really intrigued me was that there is something called ‘curing material’… to me it means they know about a tear or a rip in the spent fuel pool liner [of Unit 3 and] they tried to repair with some sort of epoxy and something that needs to cure or cure time on it before they can proceed.”
Tepco, Sept 2012: Prior to removing the steel beam which fell into the spent fuel pool… liner curing of the pool will be implemented in mid November once the preparation is complete.
- Damaged fuel rods are cracked and leaking radioactive gases in Fukushima Unit 4 pool; Wire appears trapped in racks — Another assembly bent when “mishandled during a transfer” November 14, 2013
- Nuclear Expert: Fuel rods in Fukushima Unit 4 “may not be in their original position” — Concern over “way the spent fuel is sitting in pool” (AUDIO) November 1, 2013
- IAEA Meeting: Concern of Fukushima spent fuel pool collapse as aftershock “should be caused in near future” September 24, 2012
- Kyodo: Steel beam removed from Fukushima plant’s No. 3 pool after falling on fuel racks — Another steel beam found soon after (PHOTOS) December 20, 2012
- Tepco: Fuel assemblies could be damaged from shock in Fukushima Unit 3 pool December 21, 2012