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The nuclear power plant accident in Chernobyl April 26, 1986 – KAMEDO-report 59

The Kamedo-reports are published by the Swedish Disaster Medicine Study Organisation (Kamedo), at the National Board of Health and Welfare. Observers study the medical, psychological, organisational and social aspects of disasters. The results, with a focus on experiences gained, are presented in the reports.

This report is entirely in Swedish. Only summary in English.

Summary

During the night between Friday April 25 and Saturday 26, 1986, an experiment was made in block 4 of the Chernobyl Nuclear Power Plant in order to test the ability of the turbine to power the cooling pumps whilst the generator was freewheeling to a standstill after its steam supply had been cut off. At about 01.23 the staff in the control-room of block 4 tried to achieve an emergency stop of the reactor manually. However, the control rods were too few and went down too slowly. The thermal effect increased to more than 300,000 MW (megawatt) and at 01.24 two violent explosions occurred, throwing the roof of the reactor building and lumps of material and radioactivity into the atmosphere.
There were eight persons in block 4 but also 268 building employees working on block 5 and 6 and 175 persons in block 1-3 and other buildings. A fire broke out and fire fighters arrived. After some hours, the fire fighters showed acute radiation sickness.
At the medical unit of the nuclear plant, situated in the administration building, patients from the plant were given acute, care iodine, tranquillizers and antiemetics. They were then sent to the hospital of Pripjat, where they were the same afternoon examined by radiological experts.
More than 100 out of about 200 patients with high radiation doses were later on taken to Moscow where professor Angelina Guskowa was responsible for the further treatment. In addition to whole body irradiation, several patients had also local skin injuries due to beta irradiation and bums.
During the first days the dose rate in Pripjat was 1-10 mSv/h. The inhabitants received about 30 mSv as a mean dose before they were later on evacuated.
Acute radiation sickness with lymphocyte counts less than 1,0 x109/l within 24 hours was seen in more than 100 patients. Bleeding disorders were treated with platelet transfusions. Bone marrow transplantation was performed in at least 13 cases showing signs of having received high radiation doses and chromosome aberrations. All of these patients except two died.
The total number of casualties that died, as an immediate consequence of the accident, was 31. Among those, two died already at the site of the accident. In 19 cases skin injury was an important factor and in five cases the main cause of death. Seven patients died probably because of radiation pneumonitis.
After the accident a large scale medical operation took place in the Ukraine. About 2,000 physicians and 1,000 medical students took part therein. Iodine was given in doses of 250 mg to adults, 125 mg to school children and 60 mg to younger children.
According to the Minister of Health, dr Romanenko, about 80,000 persons were listed for medical follow up at a new research centre for radiation injuries at the University Hospital of Kiev. About one million Soviet inhabitants were reported to have been medically examined in January 1989, among these about 32,000 had received medical treatment.
The consequences and risks of low dose radiation are discussed in this report.
Some of the more important experiences from the accident can be summarized as follows: • Information to the inhabitants should be immediate and in accordance with the truth; • Intervention levels and road barriers should at first be adjusted at sufficiently great distances from the site of the accident that off-limit can later be contracted; • Immediate measures must be undertaken as to drinking water supply and food distribution; • Supply of clothes, shoes and blankets is needed in evacuation situations; • In order to reduce radiation doses, sufficiently large rescue forces are needed in fire fighting and rescue work, minimizing working hours for the personnel; • Except for a limited group exposed to high doses, the immediate medical effects of the irradiation were insignificant. For most inhabitants in the Ukraine and White Russia the consequences were mostly caused by evacuations, disruption of services, lack of confidence in the information given by the authorities, uncertainty and anxiety.

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