How many hot particles are you breathing in a day?

I think it's easy to get overwhelmed by the numbers. The idea of the "banana equivalent dose" (BED) is to try to make matters clearer by bringing together all the different units of radioactivity that are commonly banded around.

If you convert everything to BED, things can actually be compared - and they are being compared to something in our experience, not just abstract numbers.

1 BED is typically taken to be 0.1µSv for informal purposes.

Dosage values (in Sv or rem) are the ones which are comparable in terms of their effects on humans.
Activity values (in Ci or Bq) are numbers of radioactive decays per second, and these will have different effects depending on the substance.

A year of average background radiation gives you 2.4mSv, which is 24,000 BED (or 66 BED per day). You're getting this whether you like it or not. You've evolved to live with and heal in this environment.

If you ingest a milligram of pure enriched Uranium (which is a visible lump, the size of a grain of sand), the radiation dose would be 40 BED (source), less than you could expect to receive per day from natural sources.

What would be in a "fuel flea"?

Of the contaminants listed above, Caesium will be the main source of radioactivity. I-131, I-132, Te-132 and others all have virtually disappeared (see graph below):

(NB the activity of Cs-137 doesn't actually increase over time – the graph shows percentages of total activity. The activity overall is decreasing, and everything apart from Cs-137 decreases fastest).

Consider the Cs-137. Firstly this makes up 6.3% of the fission products of Uranium fission, and fission products make up 3% of the fuel at the end of its time in the reactor. So the fuel elements contain between 0% and 0.19% Cs-137, depending on how long they have been in use in the reactor.

How big could a "hot particle" be? Let's say you could accidentally ingest a large fuel flea, let's say a visible particle of three-month-old fuel from a reactor, the size of a grain of sand, one tenth of a cubic millimetre. With a density of 15g/cm3, this would have a mass of 1.5mg, and contain 2.8µg of Cs-137.

The figures for Cs-137 are readily available: 1µg has an activity of 3.2MBq = 86µCi, and if ingested has a toxicity of 0.013µSv/Bq...

So putting all this together, ingesting a sand-sized particle of fuel from a reactor would give you a dose of 120 mSv of radiation, or 1.2 million BED.

That is just from the Cs-137. From the graph, we can see that this makes up only around 20% of the radioactivity of the fuel, but it gives the majority of the dose; but this 120mSv will be an underestimate – the total could be up to twice as much.

Result of Calculation for Large Fuel Flea: you'll get around a 200mSv dose if you ingest a sand-grain sized particle of fuel from a nuclear reactor three months after the reactor has shut down

Result of Calculation for Large Fuel Flea: 200mSv dose if you ingest a visible sand-grain sized particle of 100% spent fuel from a nuclear reactor three months after the reactor has shut down (details above)

This is a large dose, comparable to the dose that workers at Fukushima might expect to receive if they weren't especially careful.

The question you need to ask now is how is a sand-grain-sized piece of pure nuclear fuel going to find itself transported straight from the core of a nuclear reactor across the Pacific ocean?

Something one thousandth of this size could feasibly be considered an aerosol, carried by the wind and breathed in. The dosage would then obviously be proportionately smaller.

I'll let you muse over the implications, but that's as far as my understanding will take me.

Originally posted by IndieA

You say

That's interesting. Because 1000 rem is equivalent to 10 Sieverts, which is a massive (and probably fatal) dose of radiation over a year.

Can you provide a source that proves that please.

This stuff is not easy lets try to get all our facts straight.

Yes, I gave a link in my post on the word rem, here it is again. It's only Wiki, but it's readily available elsewhere. 100 rem = 1 Sv, which is the standard unit for radiation dose.

The sizes of doses can be compared using this table.

1000 rem = 10,000 mSv, which is a long long way down the table – a very high dose.

The source quoted by jadedANDcynical gives this as equivalent to 0.07 pCi of alpha decay. This is an example of disadtrously wrong units – my rough calculation gave 0.05 Ci, so I presume the author has confused pCi with Ci.

1 pCi, as you pointed out, is 0.000 000 000 001 Ci. Getting these two mixed up is pretty silly.

I've seen that Berkeley nuclear chat posted all over the place. I don't know who is writing on there, or how they came to be on a Bekeley Nuclear Engineering forum, but whoever they are, they're clueless and full of crap. It's a shame to see it getting passed around as if it's some reputable source.

reply to post by Bobathon


Thanks for your time, effort, and the information provided.

I am still not seeing much information on Plutonium. The EPA results make no mention to it.

This paper, www.hss.doe.gov..., speaks about it.
Those in question, results can be found on PDF page 38 or report page 33.

I have to take a break from this. My brain can't take anymore today.

reply to post by IndieA
In the reference you're citing (using pdf page numbers):

p.32: a single particle of 0.08µg of Pu-239 with activity 0.005µCi (this is 5,000pCi) is seen to cause a lesion.
p.33: since this has occurred once in less than a thousand contaminated puncture wounds, the risk is taken to be in excess of 1 per 1000 (this is a little statistically dodgy, but fair enough)

p.37: smallest activity burden in dogs suffering lung cancer was found to be 0.2µCi (this is 200,000pCi). In this case, the radioactivity is not a single large particle but 10,000,000 tiny particles in the lung.

p.38-39: the researchers are now talking about a steep increase in cancer at above 1,000 rem per year, which is a massive dose rate. On their table, they somehow present this as being given by particles of as low as 0.02pCi, and they define a "hot particle" as a particle with an activity of 0.07pCi.

As you can see by comparing with the figures on the earlier pages, there is something very amiss with the numbers on p.38-39.

p.41: the cases in the table refer to lung burdens of 24,000 to 272,000 pCi, of which about 12% is attributable to hot particles, and the number of particles involved ranges from 12,500 to 137,000, and they do appear to be taking the cancer risk to be one per thousand for each particle!

They appear to go on to use these tiny pCi numbers through the rest of the paper. This is an appallingly shoddy and confused piece of research. Someone has messed up real bad.

Do you know where this paper has come from, and how it's come to be circulated so widely?

I've posted to the dodgy Berkeley Nuclear Engineering chat thing. It was easy to register, no questions were asked.

If anyone was thinking that presence on a Berkeley Nuclear Engineering chat thing was evidence of being a nuclear engineering expert from Berkeley, clearly that's not the case.

What you have there is a bunch of clueless people talking about a really bad piece of research as if it means something.

There is very little danger from radiation dosing, except to people in Japan, and people still dumb enough (or young enough) to be drinking milk. Talking about equivalent dose is meaningless and makes me believe you are a shill for the nuclear industry.

There is a large danger in any given radioactive particle becoming lodged in our bodies (lung, colon etc) and releasing all of its radiation at the clump of cells around it. That's what gives you cancer, that's what kills people. Analyzing "how many particles" is NOT about radioactive dose, it's about the statistical odds that one of those particles will stick inside you and end up killing you via cancer.

Originally posted by Bobathon
I think it's easy to get overwhelmed by the numbers. The idea of the "banana equivalent dose" (BED) is to try to make matters clearer by bringing together all the different units of radioactivity that are commonly banded around.

One of my very favorite posts from the megathread:

Originally posted by checkmeout
reply to post by MedievalGhost

 

I have come to realise that anyone who mentioned bananas in relation to radioactivity is in fact bananas themselves!

www.telegraph.co.uk...#

This article about the Fukushima '50' is very touching

All kidding aside.

Originally posted by Bobathon

Originally posted by IndieA

You say

That's interesting. Because 1000 rem is equivalent to 10 Sieverts, which is a massive (and probably fatal) dose of radiation over a year.

Can you provide a source that proves that please.

This stuff is not easy lets try to get all our facts straight.

Yes, I gave a link in my post on the word rem, here it is again. It's only Wiki, but it's readily available elsewhere. 100 rem = 1 Sv, which is the standard unit for radiation dose.

The sizes of doses can be compared using this table.

1000 rem = 10,000 mSv, which is a long long way down the table – a very high dose.

The source quoted by jadedANDcynical gives this as equivalent to 0.07 pCi of alpha decay. This is an example of disadtrously wrong units – my rough calculation gave 0.05 Ci, so I presume the author has confused pCi with Ci.

1 pCi, as you pointed out, is 0.000 000 000 001 Ci. Getting these two mixed up is pretty silly.

I've seen that Berkeley nuclear chat posted all over the place. I don't know who is writing on there, or how they came to be on a Bekeley Nuclear Engineering forum, but whoever they are, they're clueless and full of crap. It's a shame to see it getting passed around as if it's some reputable source.

These numbers are good and when I originally looked at the 1000 rem figure something tickled my mind as I had just been looking at the very same chart you linked in the post when I made this post.

So I'll give you this and as I have not read the paper quoted, will refrain from using any of those numbers until such a time as I have been able to go through it myself, is it very long?

Originally posted by Observer99
There is very little danger from radiation dosing, except to people in Japan, and people still dumb enough (or young enough) to be drinking milk. Talking about equivalent dose is meaningless and makes me believe you are a shill for the nuclear industry.

There is a large danger in any given radioactive particle becoming lodged in our bodies (lung, colon etc) and releasing all of its radiation at the clump of cells around it. That's what gives you cancer, that's what kills people. Analyzing "how many particles" is NOT about radioactive dose, it's about the statistical odds that one of those particles will stick inside you and end up killing you via cancer.

I'm not a shill for anyone. Just trying to shed a little light on this. If I was denying the statistical odds of lodged particles giving you cancer, I wouldn't have posted the details of the part of that report which deals with the statistical odds of lodged particles giving you cancer.

The point is that the lodged particle in the report was very large (5,000pCi) and the assessed odds were "greater than 1 in 1000" because one "pre-cancerous lesion" was observed out of less than a thousand cases.

The "hot particles" being talked about as having activities of hundredths of a pCi. You see the difference, no?

The content of the air is also hundredths of a pCi (at most) per cubic metre.

Originally posted by jadedANDcynical

One of my very favorite posts from the megathread:

Originally posted by checkmeout
reply to post by MedievalGhost

 

I have come to realise that anyone who mentioned bananas in relation to radioactivity is in fact bananas themselves!

OK, point taken!

Greetings:

Meanwhile, back to the Fukushima World-Killer Nuke Meltdowns and the [color=limegreen]continuing radiation poising of our land, food and children - 24/7/365.

zorgon, what is your take on this?

Well, I spent three weeks following that Fukushima story doggedly... then in the end I found out three things...

1) Except for a handful of people and those that live in the area... NO ONE CARES...

2) We are still here... 1000's of nuke tests (especially near my home town) medical radiation, space radiation, CME's, cell tower radiation, microwave radiation... etc etc.. and we are STILL HERE.. and world population is increasing exponentially

3) Radiation is good for you

Greetings:

Thank you for your insightful and timely response.

1) We have been attempting to sound the alarm in the many nuke-related threads in our signature, and have come to the same conclusion: NO ONE CARES...

However, having spent the last six weeks on the road in the Hurricane Irene-ravaged areas of North Carolina, we were amazed - no, dumfounded - that [color=limegreen]NOT ONE PERSON we spoke with (including fellow First Responder Volunteer Firepersons) had any clue about Fukushima 24/7/365.

The Captain of the local department said that "there is no problem, or the USGOV/EPA would alert us, and it would be on television, right? (!???!)

Revised Conclusion: The people have been denied the basic information to make informed decisions as to how best "handle" the radiation poisoning nightmare.

2) Never thought that you would not be (there) "here" - after all, who would want to leave that pool? And whatever happens in "here" (there) stays in "here," (there), right mate?

3) You and Ann Coulter make such a great pair...

Glad to be back.

As we have been attempting to bring to light for over six months (!), there exists a world-wide conspiracy in the MSM to deprive the public of the facts regarding the dire consequences of the melt-throughs of the nuclear reactors at Fukushima-Daiichi.

Please listen up, people.

Your life and the lives of your loved ones may very well depend on your access to and use thereof of potentially life-saving information being kept from you by the EPA/USGOV.

The total number of days between Friday, March 11th, 2011 and Tuesday, October 11th, 2011 is 214 days.

The radiation poisoning of our people, food and land has continued unabated - 24/7/365 - for exactly 7 months.

For your edification and enjoyment (bewilderment), a few 'notable' stories that seemed to miss mass circulation and perhaps a peek at what might have been missed on the 6:00 o'clock news...:

Three days into the disaster, this FOR EYES ONLY memo circulated at the NRC.

14 March 2011
NRC ONLY Update – All 3 Reactor Cores Likely Damaged

15 March 2011
Fukushima Daiichi Units Degrading – Zirconium Fire at Reactor 4 SFP – Reactor 2 Possible Reactor Vessel Breach & Ex-Vessel Core Reaction

My goodness gracious! And we thought they (TEPCO/JAPGOV) said they had this "stabilized..." and presumably under control...

At least, that is what they (and the EPA/USGOV) would have you believe.

Fast-forward about six months to more headlines you may have missed in your local media:

21 August 2011
Fukushima Officials Worry New Discovery of Radioactive Beef Will Harm Reputation More After Farmer Confirms Cattle Not Fed Contaminated Rice Straw

21 August 2011
4,000 Potentially Radioactive Cows Without Radioactive Rice Hay May Have Been Shipped from One Farm in Namie-Machi, Fukushima

29 August 2011
Why the Fukushima Disaster Is Worse Than Chernobyl

31 August 2011
France Releases Map of Cesium-137 Deposition Across the Pacific – Shows the US More Contaminated Than Western Japan



[color=limegreen]Will this insanity ever end?

In Peace, Love & Light

tfw