Thursday, April 21, 2011

Measuring low-level radiation damage...

April 20th, 2011

Today's items:

(1) Measuring Radiation: From Becquerels to Sieverts, from birth to death by Ace Hoffman
(2) Naoto Kan should resign. He's an international disgrace (plus: "LNT") by Ace Hoffman
(3) Richard Bramhall: Guardian article: Dose is too simple a measure of risk
(4) Is this what it takes? One dead, seven wounded in Jaitapur (India) nuclear protests
(5) Michio Kaku: Blunder and Confusion at Fukushima Reactor...
(6) Fresh leak fears as Japan rocked by ANOTHER earthquake
(7) I bought a DIGILERT 100. It reads about 700 counts per hour. Is that bad?
(8) Contact information for the author of this newsletter

(1) Measuring Radiation: From Becquerels to Sieverts, from birth to death

April 20th, 2011

Dear Readers,

What are Curies, Becquerels, Rems, Rads, Grays, Sieverts, Roentgens, Q, RBE etc.?

Here are some answers (quotes are taken from my book, The Code Killers (URL for free download: ).

Let's start with a Curie: "An amount of radioactivity defined as 3.7 *10^18 decays per second... about equal to the radioactivity of one gram of pure radium. Replaced by the Becquerel (Bq)."

Becquerel: "Exactly one radioactive decay per second. Abbreviated Bq."

So those are just different measurements for the same thing: Radioactive decays per unit of time, regardless of strength or type of radioactive emission.

A Curie is a lot of radiation. A single Becquerel... not so much.

One Bq is equal to 27 picocuries, which makes sense because a picocurie (a millionth of a millionth of a Curie) is 0.037 disintegrations per second, and mathematically 0.037 times 27 equals (approximately) one. Radioactive disintegrations, of course, don't actually happen in fractional amounts. They either happen or they don't. WHEN they are likely to happen can be guessed at by the isotope's half-life, but it's only a guess.

But knowing the disintegrations per second doesn't tell you very much, really. To guess at the damage a given amount of radiation causes, you still need to know the average energy of the disintegrations. And of course, you need to know the type of emission: alpha, beta, gamma, x-ray, etc.. Each type has different properties, and each isotope's type(s) of emissions have average energy levels. Some occur together -- a gamma ray and an alpha emission. Some follow in short sequence: A beta emission followed by a gamma ray shortly thereafter.

Sometimes the decay product is also radioactive. This can go on for dozens of steps.

Gamma rays are very penetrating but have no mass and no charge. They are pure energy, traveling at the speed of light.

X-rays are less penetrating than gamma rays, having less energy, but are still damaging or "ionizing".

Alpha particles (also sometimes called alpha rays) are relatively massive (the size of helium atoms minus their two electrons) and don't travel very far before they've collided with so many things that they've slowed down, and become a helium atom out of place, grabbing two electrons and floating away. It's said that a single alpha decay has enough energy to visibly reposition a grain of sand on the beach.

Alpha particles travel at "only" about 98% of the speed of light when they are first emitted during a radioactive decay. Compared to beta particles, gamma rays and x-rays, that's slow!

Alpha particles are not much of an external radiation hazard because they can be blocked by a sheet of newspaper or dead layers of your skin (mucus membranes, eyes, and a few other exposed areas can be damaged by external alpha radiation).

But alpha particles released inside your body can do a lot of damage to molecules they collide with, and they have a double positive charge, which is also very damaging as they pass by many thousands of molecules before they slow down and capture two electrons.

Beta particles (also known as beta rays) are negatively charged particles which are ejected from the nucleus of an atom at 99.7% the speed of light or even faster. Beta particles are tiny: They are only as big as electrons, which is what they are once they slow down. Beta particles do most of their damage as their negative charge passes by other charged things -- protons and electrons.

When beta particles are traveling very quickly, their charge is not near any particular thing long enough to have any significant effect. Most of the damage occurs when they've slowed down most of the way. For this reason, the health effects for the exact same TOTAL energy "dump" per kilogram of body tissue for beta particles with low energy emission values, such as tritium, are HIGHER than for isotopes of elements with higher beta energy emission values.

But knowing the decays per second and the type of emissions, and their average energy levels, is still only a small part of understanding the potential damage from any particular radioactive release such as Fukushima Daiichi.

You also need to know the isotopic composition of the sample. Otherwise, you won't be able to estimate what the Bqs or Curies will be in a minute, or a day, or a year, or a thousand years. You need to know the half-lives of the isotopes that have been released, and the ratios of each isotope and each element.

A sample of plutonium-239 giving off one curie of radiation per hour (wow! that's a lot!) will give off about 99.999...% as much radiation tomorrow, or next year. But a sample of Iodine-131 giving off the same amount of radiation today, will give off half as much radiation in just eight days, and half as much as that -- a quarter curie per hour-- eight days after that. In a few months it will be gone completely.

But even knowing all THAT isn't nearly enough.

The next step is to estimate the absorbed dose. One measure of this is the Radiation Absorbed Dose or RAD. Grays are another way to measure absorbed dose.

But, absorbed dose still doesn't provide an estimate of the damage the radiation may do. For that, there is effective dose, which is measured in REM ("roentgen equivalent man") or sieverts. Background radiation varies greatly by location and other factors, but is usually given as almost a third of a REM per year, expressed as "320 millirem" for instance. How much that will go up because of Fukushima Daiichi is hard to estimate, but will surely be the subject of a future newsletter and much debate.

One additional, traditional, measurement of radiation is the roentgen (pronounced rent-gen (like rent again without the "a")) which is defined as 0.876 RADs "in air".

All of these yardsticks are blunderbuss attempts to estimate the potential damage from radiation as a function of energy dumped into the body. One rad equals an absorbed dose of 0.01 joules of energy per kilogram of body tissue. For ongoing radiation assaults, a time factor needs to be included: "1000 milli-sieverts per hour" or something like that. They might call that "one sievert per hour" too. Same thing. (About 6 sieverts or 6 grays, or about 600 rem or 600 rads, is considered a fatal dose, the slow and painful death coming within a few weeks of exposure. 400 to 450 rem received over a short time will kill about half the population that receives it within about 30 days.)

What is really happening when radiation damages the body, in large or small doses, is a very complex microscopic assault on living tissue. Certain elements concentrate in certain organs: Iodine in the thyroid, strontium in bones, astatine in the brain, etc.. If the percentage of radioactive strontium isotopes goes up compared to non-radioactive strontium isotopes (as it is in Japan today), the radioactive strontium will concentrate in bones and teeth. And, sometime in the future, the incidence of bone cancer and leukemia will increase.

So simply averaging the assault across "whole bodies" can miss things and is improper. Another adjustment factor is needed.

That's expressed by assigning each isotope of each element a Q (Quality factor) or RBE (relative biological effectiveness value), or the more modern "radiation weighting factor" (which works better with computers).

Analysts use these numbers to try to compare apples to oranges, or, more specifically, for example, tritium exposure in drinking water to an xray of your knee after you blow it out on the tennis court.

None of these values consider the effects of bioaccumulation: Radioactive isotopes build up in the edible portions of one living thing (strontium concentrates in beans, for instance) and are then eaten by another up the food chain to us, at the "top" (beans concentrate in Mexicans, for instance). When that happens, a dose that had been dispersed into the environment becomes concentrated again.

It's all a very inexact science, and that inexactitude is used by the nuclear industry to hide what is really nothing short of premeditated murder.


Ace Hoffman
Carlsbad, CA

The author has written extensively about nuclear power and is the author of several computer tutorials as well. His book, The Code Killers, is available online at his web site:

(2) Naoto Kan should resign. He's an international disgrace (plus: "LNT"):

April 20th, 2011

Dear Readers,

Many people think Japanese Prime Minister Naoto Kan should resign. He has bungled everything. He is an international fool.

The only slightly logical reason I can think of for him not to resign is it would, of course, add to Japan's chaos. But his support for nuclear power before Fukushima Daiichi, and his ongoing failure to inform the Japanese people -- and the world -- properly about the dangers they/we are facing, and his continued support for nuclear power throughout the rest of Japan even now, are each good enough reasons for him to resign in shame.

As shown in the quote below, PM Kan wants everyone in Japan to share in the radioactive misery of the northern prefectures by throwing caution to the wind (literally) and pretending everything is okay.

So what will happen is, for example, they'll take a farm's vegetables that are known to be highly irradiated, and mix them with vegetables from other farms that were not so badly hit, until the average level of radiation in the larger batch is low enough to pass inspection. Because inspections will be looking for averages: "Becquerels per kilogram."

The Japanese people are being encouraged -- made to feel it's their patriotic duty -- to slip as much of the hot stuff through as possible! Based on Kan's remarks, and on what happened (and still happens) throughout Ukraine after Chernobyl, and what happened after Three Mile Island to milk supplies (including for chocolate bars sold all around the world from nearby Hershey, Pennsylvania), that's what they will be doing -- are already doing -- in Japan.

And you can be sure of another rule of thumb, thank's to Kan's pronouncements: Sell the "hot" produce to foreigners, especially! Why? Because after all, the more you spread it around, the safer it is, right? If it's below legal limits, it's safe, right? So spread it around! Especially to countries that don't have a good inspection program in place. Or that just don't care.

Prime Minister Naoto Kan calls it a "sacrifice" while at the same time assuring everyone it's harmless. Eat some plutonium. Plutonium-laced spinach will make you strong. Enjoy it, even!

This "dilution solution to pollution" will not only be legal, it will be encouraged. Everyone is expected to figure that yes, they will get some poisons one day, but other days they won't. So it won't matter.

But it does matter.

Scientists agree that radiation is a "Linear, No Threshold" poison, so spreading the doses out among many people doesn't stop a single death (though it makes those deaths much harder to prove statistically, a phenomenon which the nuclear industry finds very useful). Lest you think LNT is fringe science, you should know that the US National Academy of Sciences has accepted the LNT threshold "theory" of radiation damage for many decades.

Linear no-threshold means that if one person receives one fatal dose of radiation, that person will presumably die. But if the same amount of radiation is spread out among a hundred people, or, say, a hundred thousand (a small city), or a million (a large city), divided out and distributed to everyone somehow (diabolically), one person (on average) will die from what would have been one fatal dose if given entirely to one person.

Furthermore, it doesn't matter if the total quantity is divided evenly or unevenly -- that only determines an individual's risk, not the total "communal" risk. According to the LNT theory, the total risk for the community -- one death -- remains unchanged regardless of how the dose is distributed. (NOTE: This theoretical example does NOT consider dilution in the environment, in which even more people will be exposed to the poison, but some of it will not come in contact with humans at all. By the same token, it also does not consider the billions of fatal doses that are being released from Fukushima Daiichi, it only considers the effects of ONE theoretical fatal dose. And it doesn't account for the many additional, non-fatal health effects of radiation such as inflammation, dementia, deformities, chronic fatigue syndrome, and many others.)

We don't purposefully, (at least, not often) experiment on humans even with tiny radiation doses, but the LNT data line has been indicated in thousands of different studies involving millions of lab animals who were "sacrificed" for science.

Sacrificed and apparently then utterly forgotten by society, along with the results of the studies they died so painfully for (the normal technique, when experimenting with dogs, for instance, is to remove their vocal cords first).

Because of the statistical nature of radiation doses (and many other poisons), even a so-called "fatal" dose may not be fatal. So for that reason, it's usually called a "normally fatal dose." And also for that reason, nearly all radiation damage approximations attempt to discover, not the fatal dose, but instead, the exact dosage that will be lethal for 50% of any exposed population (of beagles, fish, fruit flies, or whatever (the actual level is different for each species and each individual)). That level is known as the LD/50, and that method is used for studying many poisons besides just radiation.

Data from animal experiments, is compared against some very imprecise studies of Hiroshima and Nagasaki victims, and then used to estimate the damage that will be caused by any particular human exposure to radiation.

However, in those original Hiroshima and Nagasaki studies, damage to humans was grossly underestimated, especially for the very young. It was politically expedient to do so. Radiation damage estimates, especially for low levels of exposure, have been grossly (and correspondingly) underestimated ever since.

In the Hiroshima and Nagasaki studies, stillbirths and spontaneous abortions were not counted for the first five years after the bombings. This was a rather crucial oversight! For Chernobyl, actual doses were so poorly recorded or estimated, that all studies since then have been both difficult to design and easy to criticize as inaccurate. Instead the original bomb studies are still used as if they were unbiased and reasonably accurate.

(Eminent physician and nuclear physicist, Dr. John Gofman, used statistical studies of x-rays and subsequent patient health effects to study low level radiation damage to humans, but the larger health establishment, heavily reliant on x-rays and CT scans for their income, has ignored the late scientist's (and other's) findings. However, his results are available for consideration in several books he published during his long and distinguished career.)

With a poison which behaves according to the LNT model, dilution is the ONLY solution offered for such pollution, and it's not a very good one. Spreading LNT poisons into the environment IS premeditated murder, so you better have a pretty good reason for doing so, if you plan to do it. The nuclear industry excuses itself as "vital" because they produce electricity, which most certainly is very important.

But electricity -- and mountains of nuclear waste -- is ALL nuclear power plants produce. (One or two of them also produce a few medical isotopes, but that could be done just as well with a much smaller and safer reactor -- and ONE such reactor would be sufficient for the entire world. And, there are often other ways to obtain those isotopes or better yet, other medical procedures (such as MRIs) that can be done. So let's not get sidetracked...).

The promise from the nuclear power industry was NOT that "a little radiation is harmless" or that it's good for you. Those are excuses, and poor ones, that they like to use and want you to believe. The promise was that accidents like Fukushima Daiichi and Chernobyl simply could not happen. They promised the public, the regulators, the investors and the legislators that they had built enough safeguards into the system to make such accidents impossible.

Nuclear power is just one broken promise after another, yet even in the midst of a tragedy as large as Chernobyl or Fukushima Daiichi, statisticians and government officials can hide the deaths in reams of bad statistics.

Using their methods, nothing subtle can ever be statistically proven, or uncovered, or noticed, or anything -- the deaths are real, the cause may even be statistically obvious, but there will still be no "PROOF".

Scientists had to work very, very hard to prove the "LNT" theory -- it took 30 or 40 years for it to be accepted. Some highly qualified scientists still don't accept it. Still others believe that when microscopic clumps of billions of radioactive atoms known as "hot particles" irradiate a small area of living tissue, the harmful effect is greater than "merely" linear, and is "supra-linear".

Because Fukushima Daiichi is releasing trillions and trillions of "hot particles" every hour, and because these particles can travel all over the globe, the scientific debate about whether such particles actually cause a supra-linear effect is very important. But it doesn't negate the fact that "merely" a linear, no-threshold (LNT) rate means Fukushima Daiichi is the largest disaster in history, and will continue to kill for billions of years.

As will Chernobyl. As will Three Mile Island, Hiroshima, Nagasaki, and the uranium used in the wars in Iraq, Afghanistan, Kosovo, Libya, Palestine and elsewhere. As will the testing of such weapons in Guam, Puerto Rico, Okinawa, California, Hawaii, etc..

As will uranium mining. As will bomb testing. As will the entire nuclear industry.

Those who are in denial of the dangers of radiation poisoning should not be in charge of how MUCH radiation the rest of us are poisoned with!

But they are.


Ace Hoffman
Carlsbad, CA

The author has written a book about radiation called The Code Killers (referring to radiation's damage to the DNA code) that is available for free download from his web site:


At 07:36 PM 4/16/2011 -0700, Leuren Moret wrote:

Speaking at a news conference to mark one month since the massive earthquake
and tsunami devastated the northeastern coast of the country, Japanese Prime
Minister Kan said produce from the region around the Fukushima plant is safe
to eat despite radiation leaks.

PRIME MINISTER NAOTO KAN: [translated] From now on, people should not fall into
an extreme self-restraint mood, and they should live life as normal. To
consume products from the areas that have been affected is also a way in which
to support the area. We should enjoy the use of such products and support the
areas that have been affected. I ask you to do this.


(3) Richard Bramhall: Guardian article: Dose is too simple a measure of risk:

At 01:15 PM 4/20/2011 +0100, "Richard Bramhall" <> wrote:

The science of radiation risk has had rough treatment in the Guardian recently. Today there's an article by LLRC's Richard Bramhall which suggests why opinions are so polarised. It's below this and at:

It's short. That's all the space the editors would give it, but it makes the point: radiation risk standards are over-simplified; external radiation is reasonably well-understood, but internal radioactivity and micro-dosimetry are like the dark side of the moon.

The on-line edition has an extra paragraph about Wade Allison's book "Radiation and Reason". It's frequently cited as thorough, rational and authoritative, but it only deals with the moon's familiar face. Professor Allison's preface says, "many important topics have been omitted … in particular the subject of micro-dosimetry is treated rather briefly in spite of its importance for future understanding" (our emphasis). In fact he doesn't discuss micro-dosimetry at all, not even briefly. If people like George Monbiot, James Lovelock, Mark Lynas, Chris Goodall and Stephen Stretton would see the complexities they would understand why there are such wide disagreements about the effects of radiation on health. Maybe a more rational debate would replace the shouting and personal abuse (just look at the blog comments on-line today).

As soon as possible we will issue a statement about the Jim Green article which some people are circulating.

Guardian Wednesday 20th April 2011

The Chernobyl deniers use far too simple a measure of radiation risk:

Those who downplay the dangers of nuclear energy are wrong to focus only on dose.

In his article on "the confusing world of radiation exposure", readers' editor Chris Elliott was right to point out that getting a whole year's sunshine in an hour would fry him to a crisp (Open door, 4 April). Radiation dose rate is important. What he didn't say is that "dose density" is important too.

The "sievert", as Elliott says, is a dose unit for quantifying radiation risk. He did not add that it assumes dose density is uniform. "There are many kinds of radiation", he says, but he does not mention how they differ. In fact, external sources like cosmic rays and x-rays distribute their energy evenly, like the sun; others, notably alpha-emitters like uranium, are extremely uneven in the way they irradiate body tissue once they have been inhaled or swallowed.

Because alpha particles emitted from uranium atoms are relatively massive, they slow down rapidly, concentrating all their energy into a minuscule volume of tissue. Applying the sievert to this pinpoint of internal radiation means conceptualising it as a dose to the whole body. It's an averaging error, like believing it makes no difference whether you sit by the fire to warm yourself or eat a burning coal. The scale of the error can be huge.

Radiation protection officials fell into this averaging trap in 1941. The Manhattan Project, rushing to build the atom bomb, was creating many new radio-elements whose health effects were unknown. Summing them all ­ external and internal, alpha, beta, gamma or whatever ­ into a single dose quantity gave an impression of certainty and precision. Post war, the US National Council on Radiation Protection closed down its internal exposure committee because it took the complexities too seriously. From then on radiation effects were estimated from acute external radiation at Hiroshima and Nagasaki ­ studies which are entirely silent on internal radioactivity. In 1952 the US forced this mindset on to the newly formed International Commission on Radiological Protection (ICRP) whose advice now has almost the force of international law. In 2004 the UK scientific committee CERRIE challenged the commission's view by reporting that dose could be meaningless at the scale of molecules and cells.

If one mentions published studies which show, for example, increased cancer in Sweden after Chernobyl or the doubled risk of child leukaemia near German nuclear power stations, health officials say the ICRP model doesn't predict them: "Doses were too small to be the cause."

Chernobyl is an acid test of ICRP's risk model since, at around 2 or 3 milliSieverts, doses were close to natural background. If this level of fallout was proved to cause any health detriment, the ICRP model would fall and the economics of nuclear power would worsen dramatically. So Chernobyl denial is crucial to nuclear interests. George Monbiot's article quoted a UN committee on Chernobyl: "There has been no persuasive evidence of any health effect [other than thyroid cancer] in the general population that can be attributed to radiation exposure" (The unpalatable truth is that the anti-nuclear lobby has misled us all, 5 April). But this too is based on the flawed ICRP model; there is a lot of evidence and many scientists attribute it to the accident.

Monbiot's recent blog (The double standards of green anti-nuclear opponents, 31 March) relies on his friends Mark Lynas and Chris Goodall who in turn cite Radiation and Reason, a book by Professor Wade Allison. But Allison's preface says, "many important topics have been omitted … in particular the subject of micro-dosimetry is treated rather briefly in spite of its importance for future understanding". Monbiot and colleagues should note that in fact Allison doesn't discuss micro-dosimetry at all. It's easy to spin something if you leave out the difficult, challenging science.

ICRP has admitted that its model cannot be applied to post-accident situations. Fortunately the European Committee on Radiation Risk employs weighting factors to modify sievert-based doses for internal exposures. This won't cure the mess in Fukushima but it will mean better public protection.


(4) Is this what it takes? One dead, seven wounded in Jaitapur (India) nuclear protests:

Jaitapur is a new nuclear complex to be built in India, enabled in large part by the Indo US Civilian Nuclear Agreement of October, 2008. The French company Areva, subject of at least one bribery scandal (in Germany), is to be the manufacturer, with French financial institutions providing the money. The biggest hurdle appears to be the matter of culpability in case of a catastrophic accident: The French want none of it.

If built, Jaitapur would be the largest reactor complex in the world, with six reactors capable of producing 1650 megawatts of electricity each -- much more than current reactors. The site is known to be in a seismically active area and tsunamis are also a possibility. The Jaitapur reactors would be capable of a cascading nuclear accident that will make Fukushima Daiichi seem small by comparison.

The fishing would be ruined in the nearby oceans and the farming on the nearby lands, for miles around. Small compensations are being offered to those forced to leave. Around Jaitapur, barely 1% of the villagers have accepted compensation checks for their forced removal.

Protests turned violent when some protesters, who were expected to go toward the gates of the proposed complex, instead went to the police station and started burning police cars. Police reportedly first fired into the air, and then into the protesters when they reportedly ignored the warning shots. One protester was killed and seven wounded.

People are angry all over the world. It is a shame when the anger turns to violence of any sort, be it against police cars, or police, or each other, or anyone. But to let the situation continue, to allow nuclear poisons to be created when there isn't, and never will be, any safe way to protect humanity forever from those poisons, is a form of violence too.

Nuclear power is not necessary anywhere. There are clean energy solutions that could be implemented instead (wind, wave, solar...). Vastly safer solutions exist for India than nuclear power.

Only lies brought nuclear to where it is today. People fight pretty hard when they realize they've been lied to.

Report by Ace Hoffman


(5) Michio Kaku: Blunder and Confusion at Fukushima Reactor:

The "Sunday" he refers to is a few weeks ago, but it's a great little essay!

The following item was found at this URL:

Blunder and Confusion at Fukushima Reactor On Sunday

Michio Kaku on March 28, 2011, 12:53 PM

The utility at Fukushima (TEPCO) announced that radioactive water was found to be 10 million times normal levels at Unit 2, prompting evacuation of that site and world wide anguish and worry. This was a major story. Then, a few hours later, the utility made a rare apology and retracted that statement, stating that the water was only 100,000 times normal. What happened? How could the utility make such a blunder?

Only now is it possible to piece together the events that led to this unusual apology. First, workers at Unit 2 were astonished to find that radiation levels in the water were extremely high. This prompted them to evacuate the site immediately. Second, they rushed out so fast that they did not do a second measurement of the water. Third, the first readings were slightly incorrect. The workers got iodine-134 (with a half-life of 53 minutes) confused with iodine-131 (with a half-life of 8 days). Also, cesium-137 was also found in the water (with a half - life of about 30 years). Fourth, by confusing the two, they also got the wrong level of radioactivity. They found more iodine-134 that was actually present in the water. The shorter the half-life, the more radioactive an isotope is - the longer the half-life, the less the radioactivity. So their calibration of iodine-134 was incorrect, yielding the false number of 10 million. Fifth, the utility did not send in another crew to check the measurements, so they got their calibration wrong, but they went public with this incorrect number.

The main point, however, from the workers perspective, is that radiation levels are 1,000 milliseverts/hour. That does not change at all with this new calibration. This means that workers will come down with radiation sickness with only 15 min. of exposure. Some workers will die after 6 hours of exposure.

The meaning of all this is: if radiation levels continue to rise, and one day all workers are forced to evacuate, it means that the accident will be in free fall. If the workers abandon ship, and the cores will all be uncovered, then that is the point of no return; 3 nuclear power may inevitably have meltdowns making a tragedy worse than Chernobyl. Time is not on their side. Already, a new 6.5 earthquake has hit Japan, creating a small tsunami. Earthquakes, pipe breaks, cracks, etc. might cause radiation levels to increase until evacuation is unavoidable, then all hell might break out.


(6) Fresh leak fears as Japan rocked by ANOTHER earthquake:

Fresh leak fears as Japan rocked by ANOTHER earthquake

by Lesley Yarranton, Sunday Mirror 17/04/2011

RADIATION levels around Japan's stricken nuclear plant soared after another earthquake jolted the ­country yesterday.

Engineers fear the 5.9 quake may have caused fresh leaks at ­Fukushima Dai-ichi, north of Tokyo.

Levels of radioactivity rose sharply in seawater near the plant. It happened shortly after the Tokyo Electric Power Company had beefed up safety ­systems. TEPCO has been fighting leaks at the plant since it was crippled by a tsunami on March 11.

Politicians ­ reportedly considering breaking up the ­company ­ think the ­problems will get worse. A government adviser said yesterday: "We are far from the end. There will be mountains to climb."


(7) I bought a DIGILERT 100. It reads about 700 counts per hour. Is that bad?

My Digilert 100 radiation detector arrived yesterday. It is operational from 0.001 to 110 mR/hr (milliroentgens per hour) and is "optimized" for Cesium-137. It has a "Halogen-quenched Geiger-Mueller tube with mica end window" behind a wire mesh at the top. It detects alpha, beta, gamma, and x-ray emissions.


I've taken about a dozen hourly totals today (April 20th, 2011, Carlsbad, CA). they average just under 12 mR/hr, which is not considered a particularly alarming figure. There is a HEPA filter in the room. An outdoor measurement this evening registered about 10% higher over a period of one hour, and a room with a window cracked open slightly, and no HEPA filter, fell midway between the other counts. The detector is guaranteed calibrated within 15% of actual values.

I certainly wish I had bought this detector two months ago, so that I could compare these readings to normal background readings for this area. However, I find the apparent difference between indoor and outdoor values interesting in any case.



(8) Contact information for the author of this newsletter:

** Ace Hoffman, Owner & Chief Programmer, The Animated Software Co.
** POB 1936, Carlsbad CA 92018
** U.S. & Canada (800) 551-2726; elsewhere: (760) 720-7261
** home page:
** email: