Inside Footage from Fukushima's Deepest Crisis

PBS' FRONTLINE cringe-inducing documentary, Japan's Nuclear Meltdown, takes you about as far inside Fukushima's rupturing, quake-paralyzed nuclear plant as you want to get. We've pulled together the most jarring moments here, where Japanese workers struggled to prevent a disaster from exploding further.

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Exploding, literally. As you'll see, rescue workers and engineers were working inside a building that was literally self-destructing. The moment they describe, post-blast, nuclear materials seeping into their masks, and visions of certain death, the meltdown loosens itself from year-old headlines and feels new again. It feels real again—and for the people of Japan, it is. Be sure to watch the doc in its entirety—it's a terrific film.

DISCUSSION

We just got our internal Fukushima update at the nuke plant I work at.. and it appears some of the information released by the media is incorrect. The earthquake did not damage any safety systems at the plant, according to the data we gathered, and all the problems began after the tsunami wave hit, which was far above their design basis accident rating.

First issue: They say they 'lost' their EDG's (emergency diesel generators) because the fuel tanks for them were washed away; that's not true. The aux boiler fuel tank was washed away, and that tank is not a Q or seismic rated structure (it is also not needed in a nuclear emergency). The media always focuses on that tank and incorrectly points it out in pictures. The operators couldn't restore power using the EDG's because they could not load sequence anything since their switchgear rooms were located in the turbine building basement which was flooded out by the tsunami. Terrible design that should never had been allowed by their government according to design bases accident requirements, at least according to US standards.

Second issue: The media hyped up was the spent fuel pool. They did not lose much water from it like some media reports claimed it went dry and "caught fire". The initial earthquake caused some water to slosh out of it, but there was still over 20ft of water covering the top of spent fuel. I don't have any information on how much fuel is in their pool, but time to boil was most likely very long, if not indefinite since losses to ambient, or steam boiling could sufficiently cool it. Each bundle rack is encased basically in it's own control rod, so you don't have neutron flux, just a little decay heat. And the way the fuel is designed, lack of water prevents neutron flux as well. If the fuel has spent over 120 days cooling in the pool, losses to ambient are sufficient cooling if it is still submerged.

Third issue. The hydrogen explosions on the top floor of the reactor building are actually made to do that in the event of high pressure and high H2 levels in primary containment as result of a LOP/LOCA where you are likely to experience fuel melt. The top floor walls are designed with blowout panels, which you saw blow off in the smaller explosion. The drywell head studs stretched from >56psig pressure as a result of H2 buildup from disassociation of water, and zirc-water reactions from melting fuel. The stretched head studs let the gasses out into the top floor of the reactor building where they exploded and burned off. The second large explosion at the other unit where we saw where the debris went 500ft+ in the air was also from not properly venting via the Torus Hardened Vent line. In that case, the H2 looked to explode inside the drywell, completely blowing off the top of the containment head. They did not vent their primary containment because they claim they were waiting for evacuation orders or confirmation from their government to do so. This is completely insane that their procedures barred them from venting, and is completely the opposite in the US. It is much better to vent an early release than to lose primary containment and just let fission products spew out for months on end.

Last, we have confirmed 3 full core meltdowns with complete loss of core geometry. The fuel melted (5000F+ degrees to melt the ceramic UO2 pellets and zirconium cladding), and is in the bottom of primary containment where it hits the cement, then 'splashes' and spreads out, and interacts with the concrete so it can't go any further and cools down. (sorry folks, no China syndrome where it never stops burning through like in a movie). Also, we have confirmed they lost primary containment integrity on the two units that had the minor explosions, and a major loss of primary containment on the unit with the large explosion. There are other details I could go into that the operators closed valves, then lost DC power and couldn't re-open them, but we don't fully know the impact of some of the manual actions they took since the timeline is still sketchy. Their one RCIC turbine ran for ~80hrs and maintained water level properly, then tripped, causing a unit to melt down. Another unit had the RCIC turbine trip right away due to manual operator interaction for an unknown reason, then that unit melted down. The last unit that melted down was from manually isolating a safety system condenser leg and then losing DC power, and no ability to re-open it since the radiation levels would have killed a worker in that location.

edited for clarity/information