Following the accident in April 1986 operation of units 1 and 2 was resumed in October/November 1986, and of unit 3 in December 1987, after large-scale decontamination, and restoration and improvement to the safety of the reactors was carried out. Specific measures aimed at elimination of the causes of the accident were introduced including faster control rod insertion, improvements to the emergency protection systems of the reactor; and reduction of the value of the void coefficient of reactivity by adding 80 additional absorbers to the core and running with 2.4% enriched fuel rather than 2%. Complete inspections of all systems and equipment were carried out, and expert personnel recruited.
Meanwhile, work began on entombing the crippled Chernobyl-4 reactor in a huge sarcophagus. This task was very labor intensive because of the high radiation levels surrounding the damage reactor. By November 1986, the sarcophagus was completed. The figure below shows the entombed reactor as it now appears.
Personnel difficulties during the post-accident period (1986-1988) included operating the provisional 'watch' method of working (15 days on and 15 days off); the radiation situation, which necessitated repeated monitoring and changes of clothes; and psychological problems resulting from reaction to the accident, loss of relatives and homes, and stressful working conditions. Later, the glasnost policy also brought added pressure from mass media. Today average external radiation dose per worker is about 7mSv/year.
After the disintegration of the USSR, Ukraine's five nuclear stations united into one organisation, and the Ukrainian State Committee on Nuclear Power Utilisation (Goscomatom) was established. Ukrainian parliamentary candidates campaigned on an anti-nuclear platform, and the 1991 fire in the turbine hall of Chernobyl's unit 2, though admirably dealt with by the personnel, precipitated a moratorium on nuclear development. This, though cancelled in late 1993, adversely affected industry prestige and economics. Two IAEA safety missions in 1994, nevertheless, confirmed that Chernobyl operates well compared with other former Soviet nuclear stations. It is now among the Ukraine's top three nuclear stations. A US$360 million safety upgrading programme has been developed, to be implemented over six years; unit 2 is scheduled to reopen in 1996.
The new town for the operating personnel, Slavutich, completed 1988, continues to suffer from its perception as a 'community of the doomed', with high levels of stress among residents. A social and psychological rehabilitation programme, including visits by famous actors and theatre companies. etc.; economic support of the town's organisations and facilities by Chernobyl NPS; a UNESCO sociological centre; and holding of frequent festivities and festivals, has had appreciable results. Slavutich's birth rate is the highest in Ukraine, while morbidity and mortality indicators are decreasing.
Closure of Chernobyl NPS without compensation and a replacement power station is not viable for Ukraine because of the need for electricity supply. Expert opinion recommends a substitute 2300 MWe gas-fired thermal power plant, cost US$2000 million, to be constructed within three years near Slavutich. Expenses could be met by the world community. Meanwhile, an international scientific centre is being planned at Slavutich in which to study solutions to the problems presented by the Chernobyl accident and related issues.
Text reprinted from http://www.uilondon.org
Mr. Nosovsky is Deputy Director of the Chernobyl Nuclear Power Plant.