Currently, what is the risk of an accident occurring at the Zaporizhzhia NPP? How does this situation differ from the earlier case of Chernobyl?
According to specialists, in the case of Zaporizhzhia NPP, there are several reasons why the risks are slightly lower. First, the Chernobyl NPP reactors were of a different type; the so-called nuclear fuel “rods” were surrounded by a graphite lining. When Chernobyl NPP exploded in 1986, the combustion caused a release of radioactive substances, including the graphite that is involved in nuclear reactions, into the environment. In the case of the Zaporizhzhia NPP, there is no graphite there, and instead, water is used. Should the localised temperature increase, the water would start boiling and “bubbles” would form reducing the reactor’s power by decreasing and slowing down the rate of the nuclear reaction. The other thing, is that the reactors of the Zaporizhzhia NPP have been switched off for some time now and as a result the radioactive substances has decreased significantly. As a result, in the case of the Zaporizhzhia NPP, the situation is substantially safer. However, it is important to bear in mind that radioactive substances stay radioactive; in other words, you cannot “switch off” the radioactivity, and it can spread across a wide territory. Notably – the water intended for cooling, can itself, also become radioactive.
According to the International Atomic Energy Agency, in the highest-risk event category, i.e. an intentional blast, large territories would be contaminated with radioactive substances. They would potentially enter rivers, plants, animals, food, ground water, and ultimately, human bodies. In other words, they would enter the food chains. Radiation exposure might also have an external airborne effect: fumes containing radioactive substances would rise into the air and settle on various surfaces, including the same plants, animals, and indeed, human skin. Some of the radioactive substances might be absorbed by the human body or be inhaled through the lungs. Either way, the consequences would potentially include serious health disorders.
What is ionising radiation? What are its types and which one is the most dangerous?
Radioactive substances can emit four main types of radiation: alpha particles, beta particles (beta plus and beta minus), gamma rays, and neutrons. In terms of external radiation exposure, when humans are exposed to radiation from the outside, neutrons and gamma rays are the most dangerous, since these are the most penetrative, and can travel all the way through a human body, interacting with the atoms and molecules that make up the cells. In the case of exposure to very strong radiation, radiation sickness can result, disrupting the functioning of organs and can even be lethal. However, if one is a significant distance away from the radiation source or only exposed to it for a short time, radiation sickness rarely develops. In the meantime, beta and alpha particles are less penetrative. For example, radiation from alpha particles could be stopped by just covering the source with a sheet of paper. At first glance, alpha radiation might not seem too dangerous. But, it cannot go through the sheet of paper for a reason – it interacts with almost everything it “encounters” on its path.
Compared to alpha particles, gamma rays, albeit interacting significantly less and exposure to them also being less often, have a tremendous power to penetrate. In contrast, if alpha particles made contact with us externally, seemingly, nothing terrible would happen; they would not penetrate the deeper layers of the body. However, if they got inside the human body, for instance, if we ate contaminated food, drank contaminated water or inhaled them into our lungs, they would be particularly dangerous, as they would damage and kill all the surrounding cells. So, different forms of radiation affect us differently: alpha particles are the most dangerous ones, but only if they get inside the human body. However, most attention should be paid to gamma rays and neutrons, which are extremely penetrative and can affect the human body, even though the radiation source might be relatively far away.
What are the threats of ionising radiation to our health? Which age groups are the most vulnerable?
Children and elderly people are the most at risk. A child’s body is developing and cells proliferate very quickly: 1,000 cells are formed from a single cell, but should that cell mutate, very quickly, lots of “bad” cells would develop. Should these cells die, the body would potentially lose a high number of cells. With elderly people, the situation is the opposite: every cell is precious, as all processes in the body have slowed down. The damaged organs of an elderly person recover with difficulty. People of employable age are the most resistant to radiation.
Lengthy exposure to ionising radiation has a dual effect. If a lot of cells die, the effect can be felt very quickly. In that case, there is a likelihood that radiation sickness will appear. Symptoms include headaches, hair loss, spasms, and bleeding both from the digestive tract and other organs – in other words, there will be serious disruption to the functioning of organs. If radiation doses are substantial, a person might perish very quickly, possibly even within a few minutes. Another scenario relates to small doses, when a lot of cells survive but, some of them mutate. Then, a long-term effect manifests via oncological diseases: cancer cells appear, divide, multiply, the tumour spreads, starts pressing on the surrounding organs and disrupting their activity. If metastases develop, and the treatment is unsuccessful, death is the likely outcome. Therefore, in the case of large doses, the casualty will die very quickly; if doses are lower – oncological diseases develop, let us say, within 8–10 years. Additionally, non-oncological diseases might develop too, for instance, cataract or other illnesses.
How could residents protect themselves or reduce the effect of ionising radiation? How should they respond in the event of a nuclear emergency; what should they do first?
There are a variety of ways in which we can protect ourselves: staying inside, and limiting the entry of air from the outside; instructions might be issued by competent institutions to avoid consuming certain food products or (surface) water, along with instructions to wear respirators. However, these are extreme cases. Should an incident occur at the Zaporizhzhia NPP, it is believed that radioactive substances would not reach the surrounding countries as explained earlier, and also, we are more than 900 km away. Naturally, the possibility always remains. On the other hand, we encounter radioactive substances every day and we all already carry these substances in our bodies. Therefore, there is no need to panic; we just have to bear this in mind and be prepared for the possibility. It’s worth mentioning iodine tablets here. For many people, it is not clear what their purpose is, how they act and when to take them. First and foremost, iodine tablets should only be taken when such an instruction is issued by competent authorities. It is important to stress here, that they do not protect against any effect of the ionising radiation; they only protect the thyroid, and then only from radioactive iodine – it does not accumulate in the thyroid, and the thyroid is where the most iodine is accumulated in the whole human body. If the thyroid accumulates non-radioactive iodine, this is not dangerous. However, if radioactive iodine gains entry, this jeopardises health significantly, as a high concentration of radioactive substances is concentrated in a single part of the body. Once one has taken an iodine tablet, radioactive iodine can no longer enter the thyroid, as it is already filled up with “stable” iodine. According to the Radiation Protection Centre, in the event of an incident at the Zaporizhzhia NPP, residents of Lithuania would most probably not need to take potassium iodide tablets, but they should be available and people should be prepared.
Where can people search for information about the current radiation levels in Lithuania and for recommendations on what to do in the case of an emergency?
The main source of information is the Radiation Protection Centre. This institution is accountable to the Ministry of Health. The Radiation Protection Centre has particular responsibility for monitoring the ionising radiation levels in Lithuania (there are detectors deployed, various situations are modelled, etc.). The website of the Radiation Protection Centre provides a lot of current information about how to behave in the event of a nuclear emergency and shares the findings of numerous studies performed in this area.
