Radioactive Venting at Fukushima?

[Delta Force]

Could the hydrogen and other radioactive gasses at Fukushima have been vented prior to the hydrogen air explosions that cause damaged to the reactor buildings and containment systems? This is how Three Mile Island was saved, but because Three Mile Island still had station power it was able to use burner devices to flare most of the gas before release. Because Fukushima was suffering a station blackout it had no power to operate the burners. Neither Three Mile Island nor Fukushima had passive auto-catalytic hydrogen recombiners (standard in Europe as a result of Three Mile Island and Fukushima) which would have allowed for the safe venting of the hydrogen gas without power.

If the reactors suffered a hydrogen explosion (as they ultimately did) then any radioactive gasses would release anyways, but could a release of the unfiltered gas at Fukushima have prevented the explosions and turned Fukushima into more of a bad Windscale Fire Incident instead of the much more severe incident it did become?

 

[Nik]

Snag was the site design suffered from a *nasty* attack of 'tunnel vision'.

Despite historical records of bigger Japanese tsunamis, their sea-wall was considered adequate.

Then, rather than respecting 'Murphy's Law', they put *all* the essential back-up generators at ground level, thus ensuing any wash-over would drown them.

Similar illogic applied to the recombiners...

IIRC, UK's Windscale piles were a near-copy of a US design. However, one of the senior scientists got to thinking about the consequences of a pile-fire. The US had many miles between their station and civilisation. The UK lacked such margin for error. So, the filter stacks got added, which duly averted a chernobyl-grade evacuation...

 

[trurle]

Could the hydrogen and other radioactive gasses at Fukushima have been vented prior to the hydrogen air explosions that cause damaged to the reactor buildings and containment systems? This is how Three Mile Island was saved, but because Three Mile Island still had station power it was able to use burner devices to flare most of the gas before release. Because Fukushima was suffering a station blackout it had no power to operate the burners. Neither Three Mile Island nor Fukushima had passive auto-catalytic hydrogen recombiners (standard in Europe as a result of Three Mile Island and Fukushima) which would have allowed for the safe venting of the hydrogen gas without power.

If the reactors suffered a hydrogen explosion (as they ultimately did) then any radioactive gasses would release anyways, but could a release of the unfiltered gas at Fukushima have prevented the explosions and turned Fukushima into more of a bad Windscale Fire Incident instead of the much more severe incident it did become?

The preventive venting of hydrogen would require a total overhaul of Japanese culture. Basically, hydrogen was not vented because "venting of reactor building was not in the manuals". Explosion happened for Unit 1 just 1 hour after opening the reactor pressure valves. But Unit 3 later took nearly a day from first detection of problem to explosion. Contributing factor was what the station staff at moment did not suspected what core severely melted down and went critical again. They expected a cooler fuel and smaller hydrogen emission, and acted accordingly. Also contributing factor was an absolute absence of individual courage/initiative. Well, it helped to have zero deaths despite of 37 injuries, but contributed also to snail-paced emergency response and much increased the scale of physical destruction.

If hydrogen would be vented anyway, the total dose of radiation would slightly reduce. Not much. All mobile nuclides would escape one way or another, with the minor power of hydrogen explosion doing little to spread radioactive material. It was not much low-volatile nuclides outside of primary containment vessel to begin with. More significant change will be increase of number of radiation-sick staff (necessary to vent in time) and reduction of number of physically wounded.

 

[David Flin]

Could the hydrogen and other radioactive gasses at Fukushima have been vented prior to the hydrogen air explosions that cause damaged to the reactor buildings and containment systems? This is how Three Mile Island was saved, but because Three Mile Island still had station power it was able to use burner devices to flare most of the gas before release. Because Fukushima was suffering a station blackout it had no power to operate the burners. Neither Three Mile Island nor Fukushima had passive auto-catalytic hydrogen recombiners (standard in Europe as a result of Three Mile Island and Fukushima) which would have allowed for the safe venting of the hydrogen gas without power.

If the reactors suffered a hydrogen explosion (as they ultimately did) then any radioactive gasses would release anyways, but could a release of the unfiltered gas at Fukushima have prevented the explosions and turned Fukushima into more of a bad Windscale Fire Incident instead of the much more severe incident it did become?

Fukushima is one reason why there has been a big increase in interest in passive safety cooling. Basically, heat removal from the reactor core is independent of access to station power.

https://www.oecd-nea.org/nsd/pubs/2016/7284-five-years-fukushima.pdf

gives a summary of "lessons learned" from the NEA. It's only 80 pages, which for an NEA report, is almost back of envelope stuff.

 

[Histor32]

The preventive venting of hydrogen would require a total overhaul of Japanese culture. Basically, hydrogen was not vented because "venting of reactor building was not in the manuals". Explosion happened for Unit 1 just 1 hour after opening the reactor pressure valves. But Unit 3 later took nearly a day from first detection of problem to explosion. Contributing factor was what the station staff at moment did not suspected what core severely melted down and went critical again. They expected a cooler fuel and smaller hydrogen emission, and acted accordingly. Also contributing factor was an absolute absence of individual courage/initiative. Well, it helped to have zero deaths despite of 37 injuries, but contributed also to snail-paced emergency response and much increased the scale of physical destruction.

If hydrogen would be vented anyway, the total dose of radiation would slightly reduce. Not much. All mobile nuclides would escape one way or another, with the minor power of hydrogen explosion doing little to spread radioactive material. It was not much low-volatile nuclides outside of primary containment vessel to begin with. More significant change will be increase of number of radiation-sick staff (necessary to vent in time) and reduction of number of physically wounded.

would love to see that manual.

IN the event of a 9.0 earthquake, Tsunami's, and fires and loss of electricity and generators, and coolant, and help will not arrive for a week or more please do the following:
1. casually update resume
2. vent hydrogen, throw glass of water on reactor to help keep it cool
3. continue to update resume

It truly was a worst case scenario, mixed with not the best pre planning.

man is a smug creature who thinks he has tamed nature, until it bites him in the proverbial rear

 

[Nik]

"man is a smug creature who thinks he has tamed nature, until it bites him in the proverbial rear"

"Also contributing factor was an absolute absence of individual courage/initiative."

Yup. That's a dangerous combination...

IIRC, Fukushima staff often dined at a little port up the coast where there was a memorial for a frightful historical tsunami. The prominent 'high waterline' marker stood several metres higher than the reactor complex sea-wall...