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Twenty Years after Chernobyl Nuclear Accident

Chernobyl's nuclear accident occurred on the night of April 25th to 26th, 1986 during its test run. This was just the beginning of my work in the Institute of Nuclear Physics in Krakow, my first real job. After we had heard about the accident my boss handed me a nuclear dosimeter (radiation counter) asking to look around and check the levels of radiation. I was walking on the grounds of the Institute monitoring the level of radiation. I remember this day, I was inspecting the area, sidewalks, roads and even checking the dose of radiation on bottom of peoples' shoes.

This was already a couple of days after the accident, the main radioactive air masses from Eastern Ukraine passed already through the territory of Poland leaving the radiation, especially in the regions that experienced rains. The highest doses of radiation were detected in the northern part of Poland.. The measurements showed higher levels of radioactive cesium in some mushrooms species that are known for a tendency to accumulate cesium. The most radioactive mushrooms were found near Opole region in southwestern Poland, an area quite distant from Chernobyl.

We had rain in Krakow just a couple of days after the accident, even the local radio was warning against being outside. The rain was light, just enough to collect some radioactive dust on its way through the atmosphere and accumulate some of this radioactivity on the roads and sidewalks. So, when I walked outside the buildings belonging to the Institute with the counter, I found the most radioactivity in the small puddles of water on the sidewalks corners, and everywhere where the water was drained and accumulating. The level of radioactivity was not really health-hazardous, but it could be detected easily by the counters. The "hottest" spots were about 50-100 times more counts than the background level found inside the buildings.

First, the effects of the catastrophe in the Soviet Union were ignored everywhere outside of the directly affected Chernobyl region. The Soviet Union administration tried keep the information about the catastrophe completely secret, but it was impossible since the "unruly" radioactivity penetrated through the country's borders. I remember seeing the report on the TV from usual 1st of May, Labor Day, in Kiev as like nothing had really happened.

The Polish government on the contrary acted quite fast and efficiently. The special session of the Central Party Committee was called at 1 am in the morning, and the Chernobyl Committee was established. The Potassium Iodide (KI) solution was given to all Polish children to prevent any accumulation of the radioactive iodide in the thyroid gland. Such action did not take place in the Soviet Union until a month later, when no any negative effects of the radiation could be prevented since the radioactive iodine half-life (131I ) is just 9 days. This means that the accumulation of the dangerous radioisotope is rapid and should be treated immediately. Because of the lack of preventive action (as in Belarus, Ukraine, and the Russian Federation), the risk of the thyroid cancer in children was increased among these children who were exposed to the high doses of radiation.

Although the shock after Chernobyl helped to open Russia to the world through perestroyka (since Soviet Union could not keep the accident secret and had to admit to some errors), the accident was detrimental to the Polish nuclear science. The project of the nuclear power station, the first one that was in Zarnowiec was completely abandoned. Paradoxically, one of the biggest problems of the nuclear technology, unlike chemical technology, is that the nuclear radiation is very easy detectable even in the trace amounts. The effects of the low levels of radiation are not well understood. The low radiation dose effects can be examined only by statistical methods after many years of studies. Since the nuclear radiation is so easily detectable, every dose a bit higher than the background level is considered suspicious even though in some regions of the world people naturally live in higher radiation levels for thousands of years without any noticeable side effects. Vast areas of Poland are damaged by heavy industry, mining and industrial pollution. Still, the chemical pollution is considered less dangerous since it cannot "explode" like a nuclear bomb. Not too many people realize that the concentration of uranium and other radioactive materials in coal piles is higher than in proper operating nuclear power station. So, everything "nuclear" is still considered dangerous.

The problem of Chernobyl was mainly due to its faulty construction. The Chernobyl power station, like many Soviet reactors, did not have a containment building, which helps to withstand the high pressure and prevent a massive release of nuclear radiation to the outside. The Chernobyl reactor was of the RBMK type, built only in Soviet Union. This reactor type was graphite-moderated, therefore it was inherently unstable. It was characterized by the positive temperature coefficient (as temperature went up, power went up), which is a very dangerous. All the other reactors constructed all over the world do not have this problem. For instance in a very popular PWR (Water Pressurized Reactors) water is used in two functions - as the coolant and as a moderator(when the temperature goes dangerously up, the water simply evaporates). When the water evaporates, the moderator is gone and the chain reaction stops. Unfortunately in the Chernobyl's reactor, graphite was used for moderation. Since graphite is solid, it cannot evaporate like water, therefore the chain reaction does not stop immediately. This dangerous characteristic of the Chernobyl reactor was known by its engineers and designers; however, these reactors were still used since they could produce the big amounts of plutonium for the military. The Soviet Union had even changed its regulation code in order to be able to operate the RBMK type reactors. The earlier safety rules did not allow for such instability! Human error was just one extra factor that prevailed and caused the chemical (not nuclear) explosion that was waiting to happen eventually in one of the RBMK reactors.

When the accident occurred, Chernobyl was a part of Ukrainian Soviet Republic near the Belarus border, now this is a free Ukraine. Not too many people are aware that Chernobyl was a part of Polish multi-ethnic kingdom for many centuries! We will talk about the Chernobyl history and its Polish connection in the next part of the article: Chernobyl's Polish Connection from Historical Perspective.

 

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