Radiation and radiation detection instruments are topics that I study on an amateur basis. I recently discovered this site and the case files, including the radiation analysis report on pages 371 – 377. I’ve reviewed this, including the methodology and the numbers. What it’s telling me is incredibly fascinating.
The report indicates that testing was performed on the clothing and selected tissue and bone samples of all four hikers discovered in the ravine. All of them were found wearing clothing with radiological contamination.
In most cases, contamination takes the form of trace amounts of radioactive isotopes in dust. The report confirms this because when the clothing samples were washed in running water, the resulting radioactivity dropped significantly.
Also, I want to be clear that while the level of contamination on their clothing was above acceptable safety limits for nuclear workers, it was by no means high. It is orders of magnitude less than, say, the Chernobyl firefighters’ clothing. The level of contamination on the hikers would have caused no noticeable health effects to them.
What kind of radiation is it?What is telling in the report is the statement “When determining the type of radiation, it is established that the activity takes place due to beta particles. Alpha particles and gamma quanta were not detected.” This is incredibly surprising. Almost every scenario I can imagine that would result in people being contaminated would involve a mixture of alpha, beta, and/or gamma radiation. Beta alone just does not make much sense.
Plenty of rocks (like granite) contain uranium and are radioactive as a result. The hikers stayed at the abandoned North-2 mining settlement. Was uranium, or rocks containing it, mined or processed there? If so, I could easily see their clothing becoming contaminated with uranium dust from past mining operations. But natural uranium and its decay chain emits lots of alpha, beta, and some gamma. That doesn’t explain the lab report.
Gas lanterns are something the hikers may have used, and their mantles contain natural thorium. These wear out and need to be changed, which could conceivably spread contamination among the hikers. But natural thorium-232 is an alpha emitter, and its decay chain includes alpha, beta, and gamma. This is not what was observed in the lab report.
Radium-226 has been used in all sorts of luminous products like clocks and watches. While I don’t know if it was common in Russia, I do know that America went through a craze of quack medical cures, with all kinds of consumer products containing, or claiming to contain, radium. But Ra-226 is an alpha emitter. Its decay chain includes beta and gamma emitters. So an accidentally smashed luminous clock could easily cause contamination, but it wouldn’t match what the lab report showed.
Nuclear fission, which happens inside nuclear reactors and atomic bombs, produces many kinds of fission products. And there are also activation products. Cobalt-60 is formed when normal cobalt in steel is subjected to neutron flux inside a reactor, or as part of a bomb casing. And isotopes are formed when the uranium or plutonium absorbs one or more neutrons. When a reactor blows up or an atomic bomb detonates, the fission and activation products are all released, contaminating the environment. One very common fission product is strontium-90, which happens to be a pure beta emitter and what I think is a very likely candidate for what contaminated the hikers’ clothing. But in a fission reaction producing Sr-90, there’s also another major fission product, cesium-137, produced. Cs-137 is primarily a gamma and beta emitter.
If we assume that the radiation on the four hikers’ clothing is pure beta, then it cannot be fission / activation products. So we can rule out a nuclear weapons test, or the hikers contaminating themselves in an area where a test had occurred.
Likewise, the Chelyabinsk-40 / Mayak accident in 1957 contaminated the surrounding area with fission products that included Cs-137 in addition to Sr-90, so it would not have been a pure beta emitter.
I don’t know of any scenarios where someone could become contaminated with a pure beta emitter where an isotope wasn’t first isolated and purified in a lab for, say, scientific, military, medical, or industrial use. And that’s really fascinating because these kinds of isotopes are only used in rare, specific circumstances. A person just doesn’t randomly find themselves contaminated with Sr-90. I will speculate on this in detail below.
Now I also want to play devil’s advocate regarding fission products. But I first need to talk about how radiation is detected.
Specialized counters (either zinc sulfide scintillators or mica window Geiger tubes) can detect alpha radiation. A simple piece of paper shields against alpha but will pass most beta and gamma. If inserting a piece of paper between a Geiger tube and the sample causes the count rate to drop significantly, that is proof that the sample is admitting alpha. Alternately, a ZnS scintillator typically has no sensitivity to beta or gamma, so any count from this would show the presence of alpha. But the dosimetrist compiling this report did not observe alpha.
Beta can be differentiated from gamma by inserting a sheet of metal between the sample and a beta-sensitive Geiger tube. This should block nearly all beta but pass most gamma. So if inserting a metal shield would reduce the count rate to background levels, that indicates the sample is just emitting beta.
Now one caveat is that Geiger tubes that can detect beta and gamma are usually significantly more sensitive to beta than to gamma. I once made a rookie mistake in examining a piece of slightly contaminated clothing from the Chernobyl accident when I concluded it was a pure beta emitter; my mistake was that I forgot about the sensitivity difference, and that it was emitting gamma too, but the gamma was below my observation threshold.
For example, let’s assume fission products contain equal activity of Sr-90 and Cs-137. That means one could expect approximately 2 betas (1 from Sr-90 and 1 from Cs-137) for every 1 gamma from the Cs-137 emitted. The hottest clothing sample measured 640 counts per minute. Subtracting 90 counts per minute (the reported background), we arrive at 550 cpm. So let’s assume the sample consisted of Cs-137 and Sr-90 fission products emitting 550 cpm beta and 225 cpm gamma. But if the Geiger tube is 100x as insensitive in measuring gamma vs. beta, that implies that for an unshielded sample showing 550 cpm beta, the sample is emitting 2.25 cpm measurable gamma. This may be difficult to observe when compared to the existing gamma background, which, as mentioned above, is 90 cpm. This counting was done in a shielded “lead house” to reduce background. It’s possible, with contamination at this low a level, to miss counting the gamma. Higher contamination (say, 10,000 cpm measured beta) would produce, say, 5,000 cpm gamma, and even with a 100x sensitivity difference, 50 cpm additional gamma could be observed, which would be significant and discernible over a 90 cpm background. So such a sample would be classified as a beta and gamma emitter.
So this is a big question in my mind. Any professional dosimetrist would recognize that small quantities of contamination by fission products may produce both measurable beta and gamma that would be below the threshold of measurement with a Geiger tube. When the dosimetrist said “Dosimetric measurements of clothes showed excessive radioactivity (Betaemission only, no Alpha or Gamma-quanta) of 200–300 counts per minute (cpm) over the natural background” and “Alpha particles and gamma quanta were not detected,” how did the dosimetrist exclude gamma? If the dosimetrist used, say, a highly sensitive gamma scintillator counter inside a “lead house” to reduce background, then that may be sensitive enough to detect gamma from fission products in lightly contaminated clothing. In that case, lack of observed gamma would rule out fission products accounting for the observed beta. But if the dosimetrist simply counted in the same “lead house” using a Geiger tube and determined nothing significant above background when the beta shield was installed, fission product contamination might still be a possibility. Without knowing how the dosimetrist made this determination, it is difficult to know whether fission products can be ruled out.
When did the contamination happen?I’m wondering when the hikers’ clothing became contaminated. It could have been:
- Before the hike. They brought contaminated clothing with them.
- During the hike, but before the incident on the night of Feb 1-2.
- During the incident of Feb 1-2 that resulted in their deaths.
- Post-mortem, either before they were discovered or afterwards.
Looking at the first possibility, I can’t see any evidence to suggest that their clothing was already contaminated before the hike that could explain what was observed.
I’m aware that Krivonischenko worked at Mayak / Chelyabinsk-40, and may have been involved in the 1957 accident cleanup. But nuclear plant workers are typically very aware of contamination. In my visits inside the Chernobyl Nuclear Power Plant (admittedly, using modern safety protocols, but all this was known in 1957), you have to change clothes or are given overclothes to prevent your own clothes from being contaminated. And there are detector portals that scan all over a person’s body when they leave, which should prevent a person from leaving with contaminated clothing.
Let’s assume Krivonischenko did leave the plant with contaminated clothing. Would it have been the same clothing he packed for the expedition? And how did contamination get onto four different hikers found in the ravine? It is possible for, say, a very contaminated piece of clothing in a backpack to come in contact with and contaminate the other clothes. But I would imagine each hiker carried their own clothing. That all four hikers found in the ravine would be contaminated from Krivonischenko seems unusual.
Likewise, I am aware Kolevatov worked at a secret institute in Moscow, potentially pertaining to radiation. But that was some time before he came to UPI. If he was working with Sr-90, and contaminated his clothing, that doesn’t explain why the other three hikers found with him were contaminated too. Even if we assume that living hikers took clothing from dead hikers, and some may have huddled together for warmth, I still can’t see how all four could be contaminated with something encountered before the hike.
It seems more likely that whatever contaminated them occurred after the hike began, as that’s the only likely way I can explain all four of the hikers in the ravine being contaminated to some extent. Still, whatever did it was very unusual.
Unfortunately, the first five hikers found were buried before the four in the ravine were tested for radiation. I would be very interested in knowing whether their clothing, as well as other clothing or items in their backpacks were radioactive, but I don’t see reports of any attempts to test them. This would be useful in confirming or ruling out the second possibility.
If the dosimetrist is correct and it is pure beta, I’m at a loss for likely possibilities. Pure beta emitters often have to be separated in labs.
Regarding the second possibility, I am aware that the Soviet Union deployed RTGs (Radioisotope Thermoelectric Generators) containing Sr-90. So a damaged RTG that contaminated the environment could have contaminated the hikers if they stumbled across it. But according to Wikipedia, these were invented in the US in 1954, which doesn’t leave much time for the Soviets to adopt them before 1959. So I’m having a hard time seeing this as likely.
If the dosimetrist is not correct, fission products might account for the contamination. But that would mean that the hikers went through land contaminated by a nuclear explosion or reactor accident, or were hit with fallout from either of these. I’m having a hard time seeing these as likely, either.
Now if we look at the third possibility, that whatever caused them to flee from their tent also resulted in their contamination, we may find some interesting outcomes. I don’t think the isotope(s) contaminating the four hikers are not naturally occurring, and no natural event could have created them. To that end, I’m inclined to think that the military might have been involved to some extent.
Could the contamination have been caused by a small atomic bomb? That depends on how the dosimetrist attempted to measure, and failed to find, contamination emitting gamma. An atomic bomb would always produce gamma and beta contamination. But as mentioned above, the beta contamination was measurable while the gamma contamination wasn’t.
I’d also like to consider the possibility of military testing using conventional explosives spiked with radioisotopes. For example, if one wanted to measure the blast damage pattern of a bomb, or the distribution pattern of a nerve gas dispersal device, one could add a known quantity of, say, Sr-90. One could detonate the device over uninhabited land and then send in people with Geiger counters to measure the beta activity from the Sr-90 to produce a map with beta activity contours. Military testing of such devices could cause hikers to flee their tent and become contaminated.
But all of these possibilities would result in significant contamination of the land, in addition to the hikers’ clothing. I don’t know of any surveys done to the environment around where they were discovered.
Also, I find it interesting that, of the tissue and bone samples tested for radiation, none of the hikers’ lungs were tested. Anything that resulted in airborne dispersal of contamination could have been breathed in, at least if it didn’t immediately kill them. So that is one useful piece of data we don’t have.
Looking at the fourth option, that the contamination occurred post-mortem, I want to consider the possibility that the bodies were moved and staged. If they were transported in, say, a truck, or on stretchers, or in tarps that themselves were contaminated, this could transfer contamination to the hikers’ clothing.
It also may be possible that the bodies were contaminated in transit from where they were discovered, although this does not seem likely to me.
Why was radiation detected?This, to me, is just as important as how the contamination occurred in the first place. It seems ridiculous to think to test supposed hypothermia or avalanche victims for radiation. In 1959, I can’t imagine the equipment to detect radiation would be common, or that emergency responders would normally possess it and routinely use it for mountain expedition emergencies.
From the timeline, we know Ivanov takes over as lead investigator on March 17. The four bodies in the ravine were discovered May 5. Case file page 370 shows that on May 18, Ivanov orders the detailed radiological examination of the bodies and clothing because contamination has already been discovered.
I have heard that the helicopter pilot initially refused to transport the four bodies from the ravine because of fears of radiation, and that zinc coffins had to be procured. If this is correct (although my research here is limited, and I did not learn this from primary sources), then I would think someone must have tested the bodies already, they were found to be contaminated, and that spooked the pilot. Or, possibly, it could have been a rumor of radiation, and the rumor proved to be correct.
This level of precaution is not reasonable based on the levels of contamination measured in the report, but it is understandable because most people are not knowledgeable enough to assess actual radiation danger, hence they frequently possess irrational fear of anything even slightly radioactive.
I keep thinking that the military had to have some involvement here, and that someone in the know tipped off the investigators. Radiation just doesn’t seem like something you’d test for in a mountain expedition accident unless you had reason to suspect something was amiss.
Now, were it me in charge of the investigation, I would not want to stop at testing just the clothing and bodies of these four hikers. Other things that I believe should have been done:
- Testing the other five hikers. The last of them had been buried March 10, and I imagine exhumation wasn’t an option, given what seems like a desire to keep the investigation quiet. But was the clothing they were wearing when they died still held along with the other evidence? If so, I would think it would be logical to order it tested, too, especially after contamination was discovered on the four hikers found in the ravine.
- Testing the other possessions. What about the tent, and the contents of their backpacks and equipment? The soles of the shoes they left behind? All this would have provided so much information.
- Testing the environment where they were found.
I am surprised that more testing wasn’t done once the initial radiation was found. Then again, given what I hear about pressure to close the case, and especially if there was a military component to the contamination, I could see why Ivanov may not have been able to do a thorough job exploring this.
Still, I am very interested in learning more about the Dyatlov Pass case. I welcome any comments on this, and information that I might be missing.
Topic: Thoughts on the radiation testing report (Read 20248 times)