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Comment: Re:My daugher had 33 MBq injected last week (Score 1) 190

by virve (#47538363) Attached to: One Trillion Bq Released By Nuclear Debris Removal At Fukushima So Far

Before I sign off from this thread: Do you know of a good, authoritative account of the Fukushima event?

I don't, sorry. I find that there's tons of misinformation and downright falsehood about the event out there, both by tepco and anti-nuke activists,

Right, that's what I have found as well.

and I'm not gonna waste my time plowing through it and fact-checking every single line. I'm a technologist and as such much rather concern myself with the technology of newer safer and cleaner nuclear power than with politics.

Peace, man!

I just wanted to know if you had found something. You seemed very well informed.

Comment: Re:My daugher had 33 MBq injected last week (Score 1) 190

by virve (#47537395) Attached to: One Trillion Bq Released By Nuclear Debris Removal At Fukushima So Far

Right, that's what I forgot. You're correct that Tritium originates from reactor operations, not radioactive decay after the accident had occurred, but in LWRs it appears to be a by-product of fission reactions (1 in 10000).

Well, there is a little deuterium in the water to start with but on top of that we have so many tons of water in an intense neutron flux for 40 years. Without trying to run the numbers, I am sure there is going to be a fair amount of tritium present.

Anyhow, I also just learned about the pathway to tritium in fission yesterday. Great, I learned something new.

Before I sign off from this thread: Do you know of a good, authoritative account of the Fukushima event? I heard rumours that the Tepco crew made some unfortunate choices with the operation of the isolation condensers, and that the one measuring instrument the prioritized above all else (water level) lied to them. Now, I am not going to second guess the decisions they made under extreme duress but I am curious.

Comment: Re:My daugher had 33 MBq injected last week (Score 1) 190

First of all, I like your analysis.

By "a mess" I meant the fact that what was supposed to be inside the fuel rods came to the outside. That's plenty of a mess for me ;-)

I am not going to check your numbers but it sounds awfully little. Actually, I did check your number for Cs and I get 0.311 g assuming a half-life of 30 years and 6*10^23 for Avogadro's constant. Pretty impressive clean-up.

My vague understanding of this clean-up is that they have enormous amounts of cooling water that has been in direct contact with ruined fuel rods so the pollution is fairly well-defined. The waste-water is filtered and ion-exchanged (or whatever they do) leaving quite clean water with tritium in it. The tritium comes from (correct me if I am wrong) neutron capture in the reactor water over its life-time. It is already in the form of HTO. In principle, I guess, they could distil and electrolyse repeatedly to separate the tritium out. Or they could dump it into the Pacific Ocean. As I understand they chose the latter.

With tritium activation energy and auto-ignition temperature is less relevant not just because has been in the form of water for years but also because its beta-activity makes it insert itself readily into other molecules: A simple way to introduce tritium into a hydrogen containing molecule is to store the compound under tritium gas for a few days.

(Oh, I wrote Sr-99 above where I meant -90 and Cs-133 where I should have written -137. One typo and one genuine mistake :-( I have been too interested in atomic clocks lately.

Comment: Re:My daugher had 33 MBq injected last week (Score 1) 190

Yeah, yeah, Tc-99m. I know. It was probably gone much earlier than that because we kept her plenty hydrated and it was chelated as the dimercapto succinicate which is eliminated in the urine. And yes, the radiation is mostly benign gamma that escapes.

Similarly, apparently what gives the Japanese the most trouble at Fukushima Daiichi (as far as I understand) is tritium which is very hard to capture in waste water but luckily decays through a very low energy beta.

Still, they have managed to make a mess with plenty of actinides, strontium-99 and caesium-133 all over the place which was emphatically *not* meant to happen.

Finally, brambus we were probably both wanting to make the point that the mere activity (as measured in becquerel) is not very informative. Dose matters. Radiation type matters. Toxicity matters.

Comment: My daugher had 33 MBq injected last week (Score 1) 190

Not to trivialize Fukushima Daiichi but the current release of 10 MBq/h could be compared to the single dose of 33 MBq my baby daughter has injected last week. I was not happy with that because it seemed that the examination was for no useful purpose.

Still, the Fukushima mess has convinced me that nuclear power is a too dangerous path to thread. Unfortunately.

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