One Trillion Bq Released By Nuclear Debris Removal At Fukushima So Far

AmiMoJo writes The operator of the damaged Fukushima Daiichi nuclear plant says more than one trillion becquerels of radioactive substances were released as a result of debris removal work at one of the plant's reactors. Radioactive cesium was detected at levels exceeding the government limit in rice harvested last year in Minami Soma, some 20 kilometers from Fukushima Daiichi. TEPCO presented the Nuclear Regulation Authority with an estimate that the removal work discharged 280 billion becquerels per hour of radioactive substances, or a total of 1.1 trillion becquerels. The plant is believed to be still releasing an average of 10 million becquerels per hour of radioactive material.

I also measure distance

[Anonymous Coward]

in miles per hour. No but seriously, Bq is disintegrations per second. It's a convenient way to quantify radiation if you have one isotope or it's contained in a small area, but is absolutely ass for a situation like this.

Re:English motherfucker, do you speak it?

[Cyberax]

One Becquerel means one decay per second. So Fukushima each month emits radioactive material that adds additional 1 million decays per second to the environment.

This is a very small number, the natural activity of radioactive materials inside a human body is about 10000 Bq. One gram of radium is 37 billions Becquerels. So the whole Fukushima disaster emitted the equivalent of about 30 grams of radium, not a trivial amount anymore, but still very small on the global scale. For comparison, one ton of uranium-bearing minerals contain about 0.1g of radium.

Re:Is that a lot?

[calidoscope]

Not that much. A typical Tc99m scan involves injection a bit over a billion (10E9) bq per person, albeit half life is only 6 hours. Reminds me of a "warning sticker" for a CB radio - "Danger 5,000 milliwatts".

Re:Pick your units of radiation...

[Noah Haders]

agreed, the bequerel as a unit is bad enough, but it's even worse when people mis-use it. A bequerel isn't a count of something, like coulomb or joule (or "atoms popping tops off") but rather a rate, like amperes or watts. it's (atoms popping off) per second. so the notion of "bequerels per hour" makes no sense, or "a total of N bequerels".

the best you can do, if you want to measure the number of atoms blowing their wad over a period of time, you multiply the atoms-blowing-chunks-rate with the number of seconds in the time period. So, if something has a radioactivity of N bequerels, then there are 3600 * N atom pops per hour. Or, as we do with electricity, you could measure atomic pops with the unit bequerel-hours. You could also say "my atomic trash emitted N bequerels (or N/3600 bequerel-hours) over the course of the clean-up period.

honestly, the bequerel-hour may be the most common-sense method to measure radioactivity. It's grounded in the physical world (atomic pop-offs) unlike things like greys, and it's similar enough to watt-hour that people will use it right.

Re:Pick your units of radiation...

[Anonymous Coward]

No.

A dose released in a short amount of time is much more damaging than a dose released over a long period of time.
If you have a high dose*time over a second, the body won't be able to heal itself.
If you have the same dose over 10 years, your body can heal the damage.

Also, the Bq is a worthless unit because it doesn't tell you *what* is released.
A decay that releases a low energy beta is fairly harmless, but if it releases a 10 MeV gamma, that is very bad.

But then again, I'm just some "pro nuc AC", so maybe you should rely on people who don't know what they are talking about.

Re:I also measure distance

[Solandri]

Bq seems a fair measure to me. It's a measure of radioactivity. Would you prefer pounds (or kilograms) of X, with no measure of the rate X is releasing radiation?

It's a bad unit to use in this context because it's a measure of individual atomic decays per second. It's kinda like you asking me how far you have to walk to get to the nearest bus stop and me telling you the distance in angstroms. The scale is just completely devoid of any common reference frame for the number to be intuitively useful (not that most people have a common reference frame for radioactivity). That's why Bq is commonly used by people trying to scare the public about radioactivity - when you're talking about a lot of material like, oh, a field, it results in really, really big numbers.

Let's put it this way. A block of soil one square mile by 1 foot deep (790,000 m^3) has a natural radioactivity of 653 billion Bq [isu.edu]. If they excavated 1.1 trillion Bq of radioactive material from Fukushima, then they removed about as much radioactive substances as is naturally contained in 1.7 square miles of soil one foot deep. Of course the piece of information that we're missing (and no it's not in TFA) is how much volume of material they removed. If we knew that, we could come up with a ratio and say "Ah hah! The stuff they removed is x times more radioactive than the natural radioactivity of dirt!"

Real world consequences

[Required Snark]

Now that the Slashdot Pundits have made fun of a number, here's what's happening in the real world.

According to researchers, monkeys in the vicinity of Fukushima City had detectable levels of radioactive cesium in their muscles, while the northern monkeys did not. Researchers also found that the Fukushima simians had significantly lower white and red blood cell counts compared with macaque troops almost 200 miles away.

The researchers suggested their findings mirrored studies conducted on human health impacts following the Chernobyl disaster, where researchers found decreased blood cell counts in people living in contaminated areas.

http://www.latimes.com/science/sciencenow/la-sci-sn-fukushima-monkeys-20140724-story.html [latimes.com]

The Chernobyl site is in the process of having a New Safe Confinement [wikipedia.org] structure built, which will keep radioactive material from the disaster site from entering the environment for 100 years. Once it is in place some of the radioactive material will be broken up and moved to long term buried storage.,

In contrast, one of the articles states "The plant is believed to be still releasing an average of 10 million becquerels per hour of radioactive material." The quoted 1.1 trillion BQ figure was the result from recent debris removal.

Up to 1.12 trillion becquerels of cesium was dispersed last summer as debris was removed from the battered building of reactor 3 at the Fukushima No. 1 nuclear plant, with tainted rice later being found in Miniamisoma, Fukushima Prefecture, according to Tokyo Electric.

The amount of cleanup and debris handling remaining is immense compared to the work done in this last operation. This means that the impact of future work will be proportionally larger.

Beyond that, the three damaged cores are still not stable or safe. There is no solid information on the state of cores, or even if the core material is in the containment structure. At least one of the cores is believed to have suffered a complete meltdown and become corium [wikipedia.org].

The already severely damaged reactors are still at risk for future earthquakes, tsunamis and typhoons. Any one of these events could result in another large scale radiation event. The Fukushima disaster is not necessarily over. It's just less active.

So go on and giggle over a number. It shows that you have the collective intelligence of a retarded 11 year old.