The “Fukushima Experiment”. An email from David Chanin.

David Chanin co-authored, among other things, the following publications :

“MELCOR Accident Consequence Code System (MACCS) Model Description”

NUREG/CR-4691, SAND86-1562, Prepared by H-N Jow, J. L. Sprung, J. A. Rollstin, L. T. Ritchie, D.I. Chanin,

Sandia National Laboratories, Prepared for U.S. Nuclear Regulatory Commission. ManuscriptCompleted:

December 1989 Date Published: February 1990.

87185 GRAM, Inc.Albuquerque, NM Technadyne Engineering Consultants, Inc. Albuquerque, NM Prepared for
Division of Systems Research Office of Nuclear Regulatory Research, U.S.Nuclear Regulatory Commission
Washington, DC 20555 NRC FIN A1853, Prepared for Division of Systems Research Office of Nuclear Regulatory Research

U.S. Nuclear Regulatory Commission Washington, DC 20555 NRC FIN A1853
“PWA 00004 Pilgrim LR Proceeding 50-293 – LR, 06-848-02-LR PWA- David Chanin: MACCS2 Support Forum & The Development of MACCS2: Lessons Learned, August 23, 2006 RE: MACCS2 Economic Costs” Available at:
In 2011 and 2012 David Chanin and I exchanged emails in regard to the consequences of the Fukushima Nuclear Disaster.
In response to a question David Chanin responded with the following:
David Chanin To Paul Langley16 Jul 2011

“I think we’ll never know the truth about what’s happening there.”
—– Original Message —–
From: paul langley
To: David Chanin
Sent: Thursday, July 14, 2011 9:21 AM
Subject: Decontamination in Fukushima
David, has there been any progress or good news regarding decontamination of Fukushima City itself?

Paul Langley

David Chanin also wrote the following:
— On Fri, 22/4/11, David Chanin <> wrote:

From: David Chanin <>
Subject: hey, here’s another favor you can do me
To: “paul langley” <>
Received: Friday, 22 April, 2011, 1:45 AM


What’s amazing to me is that I seem to be the only one who thinks that I-131 levels should be decreasing with 8-day halflife because its only parents in the “standard NRC 60-nuclide list for reactors” are Te-131and Te-131m, both with shorter halflives, so they can’t be causing any I-131 buildup and certainly can’t cause the high levels of I-131 being reported in the flood of measurements that were published by TEPCO all on April 19, with measurements of seawater as far away as 15 km showing I:Cs rations of over 2:1 and as high as 3:1, but sometimes they’re equal, with few to none where I-131 is measured at levels less than Cs-134  and Cs-137 on a Bq/gram-water basis with 1000-second counting time of 1-liter sample, which matches up with usage of a gamma spectrometry machine like the GAM-AN1 by Canberra:

Can you do me a favor and ask one of your nuclear engineer contacts how and why I-131 can be over double the reported levels of Cs-134 and Cs-137, after five halflives of I-131?

I’m not a nuclear engineer who can try to run the Origen code for their reactors and the SNF pools to see what could be making the I-131.  I’m the consequence analyst who developed the MACCS2 code and have used it and its predecessor MACCS since the 1980s for nuclear accident analysis.

All I know is that when people use the MACCS2 code, which is the NRC-approved code for reactor PRA consequence calculations, and is used worldwide for well over 500 nuclear facilities and operations since its release in 1997, the MACCS2 code shows ZERO consequences from I-131 from reactor accidents after 40 days of decay.   It’s not just the direct exposure doses from groundshine and inhalation, it’s also the food doses calculated by the code with both of the “food models” that are available to the code user.  Milk from cows grazing during a large release shows very low levels of I-131 after 40 days according to the MACCS2 calculations. 

And it’s also my understanding that “normal levels” of I-131 in SNF pools should be practically zero, with the million-year, weak emitter, I-129 being the only iodine that should be detected to any significant degree in SNF water from an intact pool under normal operation.  So, if my MACCS2 code is wrong about I-131, then all the safety analyses that use to MACCS2 to calculate nuclear accident impacts are also wrong. That’s why this is an important question.

Even if criticalities are ongoing, it’s impossible for me to imagine that they could be creating so much I-131.  I’ve used “standard decay tables” that all derive from ICRP 38 and were calculated by Keith Eckerman, at ORNL, who calculates the internal and external DCFs for US and international agencies which all rely on the ICRP 38 decay chains, where decay-chain calcs are necessary because of the decay and buildup of progeny after an intake both on the ground for deposited material and in the human body from inhlaed or ingested material.

I have not tried to use this database from KfK to solve the puzzle.:

So my question, which you can forward around with all the above ane below is: Why are the I-131 levels of April 19 in “plant-water” and seawater from   so high after 5 halflives?  The NRC says that the MACCS2 code is essentially error-free. I’m curious if that’s true because I learned way back in school that there is no such thing a bug-free large-scale software such as MACCS2, which has received little-to-none verification and validation for complex scenarios.

I have no qualms whatsoever being known as the source of this request.  I’ve never pretended to know everything.

David Chanin

David Chanin also wrote the following:

“I haven’t read your blog going back past a week or so. The only reason i posted there was that it seemed like a safe enough place to post my newly formed opinion about the Japanese being used as human guninea pigs for the second time … but now by their own government. There are plenty of competent CHPs in Japan who can read and write good English. Unfortunately, competent CHPs seem to have no involvement with the events of Fukushima. The flood of garbled information with nonsense numbers coming from people driving cars around with a single pen dosimeter to take a “dose reading” is tragically funny. You’re right about ignoring the inhalation intakes. They might not know that the inhalation pathway is more important than “groundshine.” But that’s Radiation Safety 101. Every nuclear engineer in the world should know that or have it on their bookshelf. Tis a mystery. Maybe the US NRC told them they didn’t have to worry about inhalation as long as they wore face masks. But then what about analyzing their nasal swabs? Never mind. The labs are full. No need to worry. It’s perfectly safe. Time will tell … Meantime we get to do a huge experiment to see if low doses and low dose rates actually can cause any cancers other than childhood thyroid cancers. Isn’t that grand?”  David Chanin 2011.
When a nuclear decontamination expert communicates  the concerns expressed above, people need to sit up and take notice.   I know only 2 nuclear experts: my superior officers during my time in the Army.  I am a facebook friend of an Oak Ridge worker. I have corresponded with Dr. Pazit. I have conversed, by email with Paul Frame at Oak Ridge.  These are the only nuclear experts, apart from David Chanin with whom I have conversed.  So sadly the riddle of the wonky Iodine : Cesium ratios in evidence at Fukushima is quite beyond me. The obvious chemical causes I suggested are wrong. The obvious answer which springs to anyone’s mind may or may not be correct. (ie, was fission ongoing at Fukushima later than March 2001? Who knows? ).
It’s passed time for everyone to think for themselves on the basis of the best information availabe. IMO

%d bloggers like this: