Can a Student Check my Math here re: I-131 levels reported by TEPCO?

Submitted by Anonymous on Sat, 2011-04-09 10:06

Hey all. Thanks for all your time and efforts. You are doing an incredible service to the community trying to present fact in the face of much fear-can't thank you enough.

I'm an MD, we don't have to do math like this often. I compared the I-131 levels TEPCO is reporting ON SITE at Fukushima (6.1e-6 or 0.0000061 Becquerels/cm3 , source: http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110408e...) to the levels being measured in Phoenix Arizona near me thousands and thousands of miles away from Fukushima. Here is my problem...when I use an online becquerel to curie converter to compare values, the values in Phoenix are several fold HIGHER (source for Phoenix data: http://www.azein.gov/azein/2011/Radiation%20in%20AZ_Data%2014.pdf).

So what am I doing wrong?

Or have I done the math right and TEPCO is stating that their measured levels of I-131 are lower than those measured in Arizona (which of course defies logic)?

Thanks for taking your time to look at this.
Marjorie in Tucson AZ

‹ why is it that the EPA milk samples have no C-137 but UCB does? How come no Iodine-129 half-life 15.7 million years, Strontium-90, half life of 28.8 years or plutonium testing ›

It looks like Tepco is

Submitted by Anonymous (not verified) on Sat, 2011-04-09 10:19.

It looks like Tepco is reporting in cubic centimeters. To convert, you need to multiply the Tepco values by one million to get cubic meters for air readings.

thanks!

Submitted by Marjorie (not verified) on Sat, 2011-04-09 11:35.

Right you are...a units problem as usual. Thanks so much. Keep up the good work.

I see postings by a lot of less than rational people finding their way onto this board. I myself am a parapolitical researcher and truly believe in thinking for ourselves and investigating- not just believing what agencies tell us. But some people are behaving beyond rational thinking right now. Don't let it get to you. Please continue to bring us the honest facts evaluated with your own minds and education ignoring the irrational few. Stay strong.

marjorie

one more thought...

Submitted by marjorie (not verified) on Sat, 2011-04-09 11:47.

So when I follow through with the math correcting for Fukushima units being measured in cubic cm and Phoenix units being measured in cubic meters, you still get that the reported amount of I-131 being measured at fukushima is about 160 picocuries/meter-cubed while values in Phoenix are hovering around 0.1 picocuries/meter-cubed. It is of interest that on that Arizona Regulatory site they state the range of concern is above 1,000 picocuries/m3....they are essentially saying that by their standards if you were standing at fukushima you would not yet hit the level that their threshold of concern is at...interesting. A little hard to believe almost. The values and scales being used here have such a wide span that it exceeds normal intuitive thought. Its all about the units right now and understanding them. History has proven that industries ARE NOT above minimizing and tweaking the data when they have screwed up. Time will tell as this unfolds.

marjorie

Hi Marjore, I am an MD too

Submitted by Anonymous (not verified) on Sat, 2011-04-09 15:43.

Hi Marjore,

I am an MD too and have followed the news and this block. TEPCO has repeatedly misrepresented the facts.
Greenpeace has written some good articles about that.

Hi Marjorie, One more thing

Submitted by bandstra on Sat, 2011-04-09 15:38.

Hi Marjorie,

One more thing to add here: it looks your math is right, but it looks like you are using their "Detection limit density," which is the lowest activity they would expect to be able to measure (we call this the MDA or Minimum Detectable Activity). So it is not surprising that this level is below the safety limit for Arizona.

The quantity they are actually measuring is the "Radioactivity density." For I-131, they measure 7.8E-4 Bq/cm^3. If you convert this to picocuries/m^3, the number is 21,000 pCi/m^3, which is very far over your state's limits.

By the way, a pretty handy unit converter is Wolfram Alpha. Here's an example for the unit conversion I just did:

Wolfram Alpha: "7.8E-4 Bq/cm^3 in pCi/m^3"

Mark [BRAWM Team Member]

thank you Mark

Submitted by Marjorie (not verified) on Sat, 2011-04-09 17:46.

Can't thank you enough Mark for the correction. I feel much better about these numbers.

Thanks to all for your comments. It is getting into some technical math territory for us non-students who don't crunch these numbers often...I have to laugh about how crazy it gets. But thinking for yourself in these times makes sense. History has taught us that this is the most reasonable and responsible approach - to use all the fact and information available to draw your own conclusions, even if it takes a bit of work.

What the BRAWM team are offering the public right now is of great service. thank you again :)
marjorie

it's only a calculator...

Submitted by the golden kazoo (not verified) on Sat, 2011-04-09 16:59.

that's neat. helps when you have alot of data to crunch.

Isn't this getting a bit

Submitted by e^x (not verified) on Sat, 2011-04-09 16:44.

Isn't this getting a bit ridiculous?
What's next - homeworks?