The radioactive trace on the Dyatlov Pass - two conflicting opinions

Igor Pavlov

Nuclear physicist, author of book "1079. The Overwhelming Force of Dyatlov Pass". Died in 2021.

Igor Pavlov is a nuclear physicist. Graduate of the Leningrad Polytechnic Institute (now St. Petersburg Polytechnic University) with a degree in Dosimetry and Radiation Protection. He took part in decontamination activities after the Chernobyl accident, in international research programs in collaboration with specialists from the International Atomic Energy Agency (IAEA), Lund University (Sweden), Swedish University of Agricultural Sciences (SLU Uppsala, Sweden), National Defense Research Establishment, Sweden (FOA, now Swedish Defense Research Agency, FOI).

In fact, the issue with radioactivity is the most difficult one. Because there is no clear, 100% evidence of any possible option. The first thing to note is that radioactive contamination was actually found on only a few items of clothing.

Second. At that time, radioactive contamination in those places could only come from 3 sources: the accident at Mayak, tests on Novaya Zemlya, and exotic things like Rakitin’s version that someone was carrying a pure beta isotope. And it is almost impossible to prove that Rakitin is wrong. I went from the opposite - if the pollution is from one of the real sources (Mayak or Novaya Zemlya), then Rakitin’s version can not be considered.

Third. Levashov discovered only beta radiation. In fact, this is unlikely, since gamma is present almost always and everywhere (Well, except for Rakitin’s version). The bottom line is that there is a so-called sensitivity threshold of any device. Incl. and the detector used by Levashov. Taking into account the characteristics of the detector and the overall low activity of the samples (it is often said that the highest activity that Levashov discovered was comparable to the activity of a bunch of bananas. And this is true), Levashov was physically unable to determine the gamma radiation from the samples. It was below the sensitivity threshold of the device. In the case of Novaya Zemlya, the gamma/beta ratio is such that the device would "see" gamma. But in the case of Mayak, the gamma/beta ratio is much smaller. And the device does not see the gamma. Therefore, this is indirect evidence that the pollution comes from the Lighthouse.

Fourth. This is already easier. We have indirect confirmation that the pollution parameters are very similar to Mayak. We have Krivonischenko. who worked there. We have Zina, who is from a village that was affected by contamination. Therefore, it is very likely that the contamination was received before the trip.

The most important thing is not the source of the pollution, but the reason why Ivanov decided to measure something in the first place. I am sure that there have been more than one case of death of people from Mvyak or contaminated areas, but no one has ever measured their radiation.

First, I will explain the basic principles in relation to the Dyatlov group. So. There are 3 main processes.
(1) Contamination. Objects or organisms become contaminated with radioactive isotopes either through physical contact (radioactive dust or precipitation falls on clothing; in the laboratory, a radioactive solution is accidentally poured onto clothing, etc.), or through physical-chemical-biological processes in the food chain (radioactive fallout fall to the ground, then into the grass, into cows, with meat and milk into humans). In this case, contaminated objects or organisms emit radiation
(2) Emission. This radiation affects other objects and organisms that are irradiated
(3) Exposure. This means that interaction occurs between radiation particles (electrons, protons, gamma, etc.) and the substance of the irradiated object or organism.

Now the most important thing. Only process (2), radiation, can be physically measured. This is exactly what Levashov did. He measured the number of particles that were emitted by contaminated samples per unit time (recorded the number of times particles hit the detector). Based on these measurements, it is possible to calculate the activity of the contaminated sample (roughly speaking, how much it is contaminated, how many radioactive substances are on the sample) and the degree of radiation exposure of the body that is (or has been) exposed to radiation from this contaminated sample (what is called the radiation dose). But processes (1) and (3) cannot be measured. You can only calculate from the parameters using the results (2).

When Levashov measured contaminated samples (clothing or samples of human tissue) he determined precisely the degree of contamination of the samples, because they themselves emitted radiation (i.e. they were contaminated either due to physical contact (clothing), or through the food chain (human tissue).

But it is impossible to measure the degree of exposure of internal organs from external radiation (for example, from clothing). This can only be calculated. For example, a dosimeter can show the radiation dose only when it is with a person at the reactor. If you apply the dosimeter to a person after that. When he leaves the reactor compartment, the dosimeter will show 0, because the person himself does not emit anything after irradiation. And the detector "counts" the reactor radiation. which affects a person.

Therefore, it is in principle impossible to measure or see anything on samples that have been exposed to radiation (naturally, until symptoms of radiation sickness begin).

When we refer to histological samples, I understand this as samples of human organs prepared for histological examination. These are thin sections for examination under a microscope. The case files contain the results of histological studies for the last four.

Levashov did not examine histological samples (as understood above), but ash from human tissue samples. That is, formally these are not samples for histological studies. Histological samples were not submitted for radiometric examination.

Levashov's studies established the fact of minor radioactive contamination of human tissue samples. This means that somehow the isotopes ended up in the samples = in the human body. For example, this is possible when consuming contaminated foods (common in areas contaminated after radioactive accidents). That is, the samples themselves were a source of radiation. This is not the same as if they were irradiated from an external source (on the body or outside the body). The fact of external irradiation cannot be determined by examining samples using radiometric instruments.

Игорь Павлов - физик-ядерщик. Выпускник Ленинградского политехнического института (ныне Санкт-Петербургский политехнический университет) по специальности "дозиметрия и защита от излучений". Принимал участие в дезактивационных мероприятиях после аварии на Чернобыльской АЭС, в международных исследовательских программах в сотрудничестве со специалистами International Atomic Energy Agency (IAEA), Lund University (Sweden), Swedish University of Agricultural Sciences (SLU Uppsala, Sweden), National Defence Research Establishment, Sweden (FOA, ныне Swedish Defence Research Agency, FOI).

На самом деле вопрос с радиоактивностью — самый сложный. Потому что нет никаких явных, 100% доказательств любого возможного варианта. Прежде всего нужно отметить, что на самом деле радиоактивное загрязнение было обнаружено всего на нескольких элементах одежды.

Второе. В то время радиоактивного загрязнение в тех местах могло быть только от 3-х источников: авария на Маяке, испытания на Новой Земле и экзотика типа версии Ракитина о том, что кто-то нес чистый бета-изотоп. И то, что Ракитин не прав, доказать практически невозможно. Я шел от противного — если загрязнения от одного из реальных источников (Маяк или Новая Земля), то версию Ракитина можно не рассматривать.

Третье. Лавашов обнаружил только бета-излучение. На самом деле это маловероятно, т.к гамма присутствует практически всегда и везде (Ну, кроме версии Ракитина). Суть в том, что есть так называемый порог чувствительности любого прибора. В т.ч. и детектора, которым пользовался Лавашов. С учетом характеристик детектора и общей малой активностью образцов (очень часто говорят, что самая большая активность, которую обнаружил Лавашов, сравнима с активностью грозди бананов. И это правда) Лавашов физически не мог определить гамма-излучение от образцов. Оно было ниже порога чувствительности прибора. В случае Новой земли соотношение гамма/бета такое, что прибор бы «увидел» гамму. А вот в случае Маяка — там соотношение гамма/бета значительно меньше. И прибор не видит гамму. Поэтому это косвенное доказательство того, что загрязнение как раз от Маяка.

Четвертое. Это уже легче. Мы имеем косвенное подтверждение, что параметры загрязнения очень похожи на Маяк. Мы имеем Кривонищенко. который там работал. Мы имеем Зину, которая из деревни, которая попала в зону загрязнения. Поэтому с очень большой вероятностью загрязнение было получено до похода.

Самое главное — это не источник загрязнения, а причина, по которой Иванов вообще решил что-то измерить. Я уверен, что был не один случай гибели людей с Мвяка или загрязненных районов, но никто и никогда не измерял у них радиацию.

Сначала я на пальцах объясню основные принципы применительно к группе Дятлова. Итак. Есть 3 основных процесса.
(1) Загрязнение (contamination). Предметы или организмы оказываются загрязненными радиоактивными изотопами или путем физического контакта (радиоактивная пыль или осадки выпадают на одежду; в лаборатории р/а раствор случайно выливается на одежду и т.д), или при физико-химических-биологических процессах в пищевой цепочке (радиоактивные осадки выпадают на землю, далее в траву, в коров, с мясом и молоком в человека). При этом загрязненные предметы или организмы излучают радиацию
(2) Излучение (radiation, emission). Это излучение воздействуют на другие предметы и организмы, которые облучаются
(3) Облучение (exposure). Это значит, что происходит взаимодействие между частицами излучения (электроны. протоны, гамма и т.д) и веществом облучаемого предмета или организма.

Теперь самое главное. Физически измерить можно только процесс (2), излучение. Именно это и делал Лавашов. Он измерял количество частиц, которые излучали загрязненные образцы в единицу времени (фиксировал число попаданий частиц в детектор). На основании этих измерений можно рассчитать активность загрязненного образца (грубо говоря — насколько сильно он загрязнен, сколько р/а веществ находится на образце) и степень облучения организма, который подвернется (или подвергся) облучению от этого загрязенного образца (то, что называется доза облучения). Но измерить процессы (1) и (3) нельзя. Можно только рассчитать из параметры, используя результаты (2).

Когда Лавашов измерял загрязненные образцы (одежда или образцы человеческих тканей) он определял именно степень загрязнения образцов, т.к они сами излучали (т.е были загрязнены или из-за физического контакта (одежда) или по пищевой цепочке (человеческих ткани).

Но измерить степень облучения внутренних органов от внешнего облучения (например от одежды) невозможно. Это можно только рассчитать. Например, дозиметр может показать дозу облучения только когда он находится вместе с человеком у реактора. Если приложить дозиметр к человеку после того. как он выйдет из реакторного отсека, то дозиметр покажет 0, т.к сам человек ничего не излучает после облучения. А детектор «считает» излучение реактора. которое воздействует на человека.

Поэтому измерить или увидеть что-то на образцах, которые подверглись облучению в принципе невозможно (естественно, пока не начались симптомы лучевой болезни).

Когда говорится о гистологических образцах, я это понимаю как образцы человеческих органов, подготовленные для гистологического исследования. Т.е тонкие срезы для исследования под микроскопом. В УД есть результаты гистологических исследований для последней четверки.

Левашов исследовал не гистологические образцы (в понимании выше), а золу от образцов человеческих тканей. Т.е формально это не есть образцы для гистологических исследований. Гистологические образцы не передавались на радиометрическую экспертизу.

Исследования Левашова установили факт незначительного радиоактивного загрязнения образцов человеческих тканей. Это значит, что каким-то образом изотопы оказались в образцах = в организме человека. Например, это возможно при употреблении загрязненных продуктов (обычное дело в загрязненных после радиоактивной аварий районах). Т.е образцы сами являлись источником радиации. Это не то же самое, что они облучались от внешнего источника (на теле или вне тела). Факт внешнего облучения невозможно установить при исследовании образцов с помощью радиометрических приборов.

Ryan Pierce

Letters are published with his permission

I live in Chicago in the United States and recently earned a Bachelor of Science in Engineering - Electrical Engineering degree from Arizona State University. I am now a graduate student at ASU. My studies focus on nuclear power. In my spare time, I collect and restore radiation detection equipment, research nuclear history, and explore related sites, including three trips to the Chernobyl Exclusion Zone in 2013, 2015, and 2016.

I was thinking about you recently, and I'm glad to hear about your successful expedition!

I'm about to head back to graduate school and I’m taking more nuclear courses.

I came to the realization that the radiation on the ravine bodies could be explained if someone dumped a significant amount of a chemical containing potassium on them, and the potassium remained in significant quantities in the clothes. It would explain the beta counts. Potassium is also a gamma emitter, but because Geiger tubes are far more sensitive to beta than gamma, and the level of beta was significant but not high, the gamma would probably fall below the threshold of detection.

In particular, I speculated how this could support your theory. Bodies were taken to the Ivdel morgue and later returned to the mountain to be staged once it became known that this was the famous Dyatlov team, a high profile search effort was underway, and it would be disastrous if the the truth about the tree falling on their tent was known. When it became clear that some of the bodies had severe enough trauma from the tree falling on them that nobody would believe they left the tent and died of hypothermia, those bodies were hidden in the ravine, and potassium hydroxide (a cousin of lye, sodium hydroxide) was dumped on them in a failed attempt to speed decomposition so they wouldn’t be found.

First, I want to clarify that I'm not a chemist, but I have taken university level courses pertaining to radiation, its detection, and measurement. My theory is just a theory, and I have no idea if it’s correct. But I can say with as much certainty as is possible regarding anything in the case files that the statement that only three pieces of clothing are contaminated is not true at all. It is a misrepresentation of the radiation testing report. All 9 pieces of clothing tested are radioactive beyond background levels! This is a critical misunderstanding that I want to correct.

I am not suggesting experienced criminals are involved. If anything, I'm suggesting the opposite. People seem to think it’s possible to dissolve bodies in lye due to rumors, fiction, etc. But in practice, it really doesn’t work. I'm thinking more along the lines that someone involved in moving the bodies and staging the scene had bags of caustic potash for some reason and thought it would be possible to get rid of four of the bodies by dumping them in the ravine and covering them in caustic potash so that the searchers wouldn’t find them. It may have been a hasty, impulsive, and/or desperate decision made in part because of time pressure to finish the job. I'm not suggesting it was a calculating, experienced, or even mad and sadistic criminal.

If so, they were clearly wrong, seeing as the four bodies were not dissolved and eventually were discovered by the search party. Again, this points to an amateur, not an experienced criminal.

Otherwise, I have no good explanation for the radiation measured. That report is so detailed, quantified, and specific about what was and was not detected that it is so unusual. Just about anything can be ruled out.

* Thorium lantern mantles, natural uranium dust, radium watches, etc. These would all have detectable alpha emissions so must be ruled out.

* Fallout from nuclear tests. The incident happened in the middle of a nuclear testing moratorium. The US was watching the Soviets for any cheating, and none was detected.

* Kolevatov doing nuclear work in Moscow, or Krivonischenko doing cleanup of the Kyshtym disaster. The Soviets gave people work clothes so they wouldn’t contaminate their personal clothing. Yes, that may not have been perfect. And yes, there may have been clothing exchanged during the night as people died and those still surviving tried to stay warm. But radiation doesn’t magically jump from one piece of clothing to another. 9 samples from pieces of clothing worn by the four hikers all showed elevated radioactive contamination. I don’t believe that could have been the fault of one person bringing contaminated clothes on the expedition.

Natural potassium is slightly naturally radioactive, which could account for the numbers observed, but it would have to be large. This would mean the 75 square centimeters of Dubinina’s brown sweater would need to retain 3 grams of pure potassium or a greater amount of a potassium-containing chemical. This is what causes me to question whether someone shoveled caustic potash onto the four ravine bodies.

Otherwise, I'm rapidly running out of explanations, and we would need to talk about man-made isotopes, and whether the hikers got caught in a military dirty bomb test, or found a leaking radioisotope thermal generator, all of which seems incredibly unlikely.

I've examined Levashov's report in detail. First of note is the background number. The background reading on the day the clothing samples were measured before washing was 90 counts per minute. The background reading after the sample washing was concluded, likely the next day, was 100 counts per minute. Small fluctuations like this are normal. I’ve observed them myself with my own instruments.

It follows that everything above 90 - 100 counts per minute is likely radioactive unless it’s a statistical fluctuation.

In Table 2, the first sample, soil from #1, measures 96 counts per minute. 96 is close enough to 90 that it is not considered radioactive.

Now let’s look at sample #2, waistband from Kolevatov. There are two numbers for counts per minute before washing, and two numbers after washing. The two before are 384 and 300. It seems they took two measurements. Possibly they measured both sides of the fabric? They also seemed to use the larger of the two numbers, not the average, for the rest of the computations, which makes sense if they want to be cautious.

384 - 90 (subtracting the background count) gives you 294 counts per minute. But the next thing to note in the report is the beta detection efficiency of the detector. The conversion factor is listed as 8.9 which means for every 1 pulse detected, there were 8.9 actual counts. So 294 * 8.9 = 2617, rounded to the 2600.

- 2 -

It is important to note that this "Radioactivity of contaminated area" column has already had background radiation subtracted from it! So any number in this column means the sample is radioactive!

Likewise, after washing, count rates were 244 and 218. Taking the highest, subtracting the background of 100 and multiplying by 8.9 yields 1282 cpm which is rounded to 1280 in the report.

If you look at the data, you’ll see that with the exception of sample 1, everything is well above the 90 or 100 cpm! This is very much abnormal. It means EVERYTHING in the clothing samples, with the exception of soil measured as #1, is radioactive! The smallest reading before washing was sample #6, the bottom of Thibault-Brignoles’ trousers. Even that is 33% above background, which is likely above any statistical noise and means it is really radioactive. This is reflected in the “Radioactivity of contaminated area” column. Again, any number there implies the sample is radioactive above background.

Because the clothing pieces are all different sizes, it follows that if they were equally contaminated, the larger pieces would be more radioactive than the smaller pieces. So the last column attempts to correct this by normalizing this to counts per 150 cm2 of area. So, for example, sample 2 before washing is 2600 beta emissions per minute. It has an area of 70 cm2. If you take 2600 * 150 / 70 = 5571 which is rounded to 5600 in the last column.

Now we get to the source of the confusion. The expert, Levashov, then compares the clothing to what appears to be a Soviet industrial safety standard:

For example, according to the sanitary rules that exist in our country, the contamination in beta particles from 150 cm2 per minute should not exceed 5000 decays (washing), and after cleaning (washing) there should be only the natural background, i.e. as much as it gives cosmic radiation to all people and all objects in a given locality, this is the norm for workers with radioactive substances.

This is likely a standard for nuclear workers. So if you apply the limit of 5000 counts per minute per 150 cm2 to the rightmost column of Table 2, you will see that only samples 2, 3, and 10 exceed this. And Levashov calls them out specifically:

Further investigation allowed maximum contamination to be established on different spots of clothing:

Brown sweater from №4: 9900 cpm on 150 cm2
Bottom part of pants from №1: 5000 cpm on 150 cm2
Belt of sweater from №1: 5600 cpm on 150 cm2

What this means is that if the hikers were workers in a nuclear plant, the contamination on those three pieces of clothing should not have occurred. The contamination on the rest of the clothing was acceptable for nuclear workers.

Here we get to the source of the confusion. The report does not say that only 3 pieces of clothing were contaminated. It says that all 9 clothing samples were contaminated with beta emitting radionuclides, but only 3 were contaminated beyond Soviet safety standards.

Saying only three pieces of clothing are radioactive is like standing beside a road, watching police pull over three cars for speeding, and saying that those three cars are moving, but the rest of the cars must be standing still. That’s clearly not true.

All four of the hikers found in the ravine were wearing clothing that was measurably radioactive above background levels. This is a critical fact. Assuming Levashov's report is correct (considering it would be difficult for him to make a mistake of this magnitude, he would be subject to penalties for lying, and, if anything, the officials would probably have preferred the report to say there was no radiation at all) then the contamination was spread among 9 pieces of clothing on all four hikers.

What’s worse is that they were found with at least some of their clothing subjected to running water which could wash contamination out. That they were found with that much contamination implies a potentially significantly higher level of contamination in the past.

I can also address radioactive contamination on clothing. I have been in the Chernobyl Exclusion Zone three times, including receiving professional training from plant staff as part of a professional training program in detecting contamination and decontamination. I’ve had to deal with this personally.

Radioactive contamination can best be perceived like dust. If you’re in a room with the air filled with lots of dust, your clothing will get dusty. If you rub against a dusty surface, your clothing will get dusty. If two pieces of clothing rub together, dust can transfer from one to the other, but usually only a small percentage does. But it is impossible otherwise for dust to jump from one piece of clothing to the other, just because they are in proximity.

This is why the case fascinates me. There is no way, even if Krivonischenko and/or Zina brought back contamination from the Mayak Chelyabinsk area, that it could have transferred to all 9 clothing samples on all four ravine bodies. Taking clothing off the dead won’t easily account for it. The hikers huddling together for warmth won’t explain the number and variety of transfer locations of contamination.

That’s why I believe they didn’t bring contamination with them from Mayak, their university, or Moscow nuclear work. Either something they experienced on the hike contaminated them in the clothes they died in, or something contaminated the four ravine bodies after death.

As for my potassium hydroxide theory, I'm not terribly confident in it, but it does suggest why all four bodies wore contaminated clothing. Also, human bodies only take in chemicals while they are alive. If the bodies had potassium hydroxide dumped on them, and it didn’t successfully react with and dissolve them (seeing as they were later found) then I’d expect none of the internal organs would be contaminated. Maybe exposed skin could be chemically burned, partially dissolved, and contaminated, but if we assume potassium hydroxide was dumped on clothed bodies, the clothing would protect the skin. (Again, these are not smart criminals!) It isn’t clear from Table 1 what part of the body that all the skin samples were taken from, so, especially if clothing covered said skin, it might not be contaminated.

Anyway, regardless of what you think of my potassium hydroxide theory, I do hope I have convinced you that all four bodies wore contaminated clothing. That is a fact of the radiological report.


You can discuss this topic on Dyatlov Pass Forum.



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