This document presents a contribution by the Ukrainian Ministry for Extraordinary Situations and for Protection of the Population from the Chernobyl Disaster, which is intended to be a reference document for discussion at the Deputies 652^nd meeting (15 December 1998, B level) under item 9.2, "Assistance to the victims of the Chernobyl disaster".

Permanent Delegation of Ukraine

to the Council of Europe

To Mr L G Davies

Secretary of the Committee of Ministers

Council of Europe

Strasbourg, 19 October 1998

Dear Mr Davies,

We hereby request you to transmit to the Delegations of member States the (attached) document drawn up by the Ukrainian Ministry for Extraordinary Situations and for Protection of the Population from the Chernobyl Disaster, for examination at the 645^th meeting of the Ministers' Deputies under the agenda item "Assistance to victims of the Chernobyl disaster".

Yours sincerely,

Olexandr Kupchyshyn

Permanent Representative of Ukraine

As a result of the accident at the Chernobyl Nuclear Power Plant on 26 April 1986, Unit 4 was completely destroyed and approximately 11 EBq of radionuclides were released into the environment. About 600 PBq long-life radionuclides remained in the destroyed reactor. In addition, nearly 8 PBq of high, medium, and low-level radioactive waste was buried in 800 temporary disposal sites. About 30,000 km² of territory in Belarus, Ukraine and Russia have a radioactive contamination density exceeding 185 kBq m². All this creates an additional risk for the population in the affected area.

The comprehensive evaluation of the 1986 Chernobyl accident has shown three major risks related to it:

- risks of a negative effect of the accident on human health and the environment;

- subjective risks related to the perception of the accident and economic risks;

- risks related to a reassessment of the safety of nuclear power operation.

 

The first category of risks includes:

1. Risks related to incomplete control of high-active radioactive waste in the Sarcophagus object.

2. Risks related to an incomplete control of radioactive waste in RWDs and RWTSs of the Exclusion Zone.

3. Risks related to the high levels of surface contamination of the Exclusion Zone territories.

4. Risks related to additional irradiation of the population of Ukraine with radionuclides outside the Exclusion Zone.

1. As of 1 June 1996, the Sarcophagus object had about 6x10¹⁷ Bk in the form of highly active radioactive waste. Radiation and other physical and chemical effects lead to the transformation of radioactive waste. One of their decomposition products is radioactive dust. In the event of the Sarcophagus downfall, about 2,000 kg of the dust containing about 40 kg of fine dispersible fuel may form a radioactive release of about 100-200 m high. Depending on the weather conditions, this may result in a significant pollution of the territory within 30 km around the Chernobyl NPP and in considerable exposure of personnel.

Another process related to the transformation of radioactive waste in the Sarcophagus object is a possible "wash out" of uranium and plutonium from radioactive waste and there may be a concentration of them in certain places. This process is difficult to forecast in detail and, though at the moment there is no threat of the formation of a critical mass, nobody can guarantee that it will never happen in the future.

The third threat is a possibility of pollution of environment due to the radioactive water migration which is annually accumulated in the Sarcophagus object in the rate of about 1,000 tons.

Therefore, it is obvious that the problem of the radioactive waste stabilisation in the Sarcophagus object and ensuring their subcriticality requires an immediate resolution.

At the moment, the following possible solutions are being discussed:

i. Concreting. This solution is based on the idea of pouring the radioactive waste in the Sarcophagus with concrete or its modifications with the addition of neutron absorbers (eg boron). In this case, the possibility of the radionuclides re-distribution in the Sarcophagus will be limited therefore the chain reaction will be impossible. An advantage of the project is low cost and low exposure of personnel. A major disadvantage of the project is that in one hundred years a problem of the burial of plutonium waste and other transuranium elements containing in the concrete may arise. Thus this solution makes the future generations responsible for the transformation of the Sarcophagus into a completely safe object.

ii. The stabilisation of the Sarcophagus, the construction of the Sarcophagus and the removal, processing and burial of waste are proposed. An advantage is an up-to-date and complete solution of the problem. Disadvantages are high cost and high irradiation exposure of personnel.

Other proposed solutions (like, for example, the complete burial of the Shelter in the mine at significant depth) are not properly developed and exist only in the form of ideas. In any case, the Sarcophagus problem needs to be resolved, since a complete or partial demolition of the Shelter will result in a significant contamination of the nearest (up to 30 km) area. The probability of this happening is constantly growing.

2. Keeping of radioactive waste in RWDs and RWTSs does not comply with national and international recommendations on the storage of radioactive waste. This means that, at the moment, a complete control of radioactive sources does not exist. However, the analysis has shown that collective exposure doses of the Ukrainian population related to radionuclides migration from burial places are much lower than the natural (background) radioactivity. On the other hand, the lack of any guaranteed control of the radioactive sources in different situations creates an additional risk which must be minimised. In the current conditions any unauthorised access to burial places, at least for several centuries, must be prohibited (a half-life of the most biologically active radionuclides ²⁴¹Pu and ²⁴¹Am are 14.4 and 432 years, respectively).

3. In the Exclusion Zone and some other locations, the surface contamination density with ¹³⁷Cs reaches 740,000 kBq m² (20,000 Ci km²) and higher. This means that in these locations the soil in fact is radioactive waste. Natural ecological systems in these locations are significantly affected by radiation. However, any radiobiological effects important for ecological systems have not been observed. That is why, considering the uniqueness of the situation, when all elements of the ecological system are under a significant radiological effect, a long term monitoring of these systems together with the scientific support is absolutely required.

Vertical and horizontal radionuclide migrations lead to the local contamination of the underground waters. At the same time, there are large amounts of radionuclides on the surface that are of potential danger. The migration processes in such vast territories may have characteristics that have not yet been studied, therefore, a permanent monitoring of radionuclides in interrelated elements of the environment and the verification of appropriate forecasting models are required. Nowadays, the transfer of radionuclides outside the Exclusion Zone does not significantly contribute to the total exposure dose of the Ukrainian population.

Risks related to the effect of the "Chernobyl" exposure on human health depend on the effective individual and collective exposure doses.

Every year individual doses in all contaminated territories decrease. Over 80% of a life (during 70 years) individual dose has already been acquired. At the same time, in practically all towns and villages located in the contaminated territories, average annual doses of the "Chernobyl" origin do not exceed average exposure doses of the residents of Ukraine from natural radiation sources (5 mSv · year^-1). Only in 50 locations is there an average individual dose of more than 1 mSv · year^-1, which is a criteria for the classification of these locations as the area of voluntary resettlement.

The collective exposure dose from the "Chernobyl" radionuclides is about 1/57 of the collective exposure dose from natural radiation sources for the total population of Ukraine. In one of the most contaminated regions – Zhitomir region, the exposure dose caused by natural radionuclides is 7 times higher than the "Chernobyl" dose. In the most contaminated areas, considered to be the areas of forced resettlement (eg in the villages of Denisovichi, Polessiy district, Kiev region, the surface contamination density is 555 kBq m^-2), the exposure dose from the "Chernobyl" radionuclides was about the same as that of natural radionuclides, provided people would have lived there and eaten locally produced food.

The contribution of the external exposure dose in the collective dose was quite significant only during the first years after the disaster. Currently (for 1997), over 70% of the "Chernobyl" collective dose is related to the doses of internal exposure, where radiocaesium dominates. The internal exposure dose almost completely depends on food products, in which the content of radiocaesium is related to its transfer in the "soil-plant" chain. The research conducted has shown that the radiocaesium transfer in agricultural produces is lowering with time. Therefore, the contribution of the "Chernobyl" component in the collective exposure dose will gradually decrease.

At the moment, in 978 locations of the 2,293 considered to be the areas of guaranteed voluntary resettlement, exposure doses actually assessed are even significantly lower than those ceiling doses which would allow to qualify them as such areas.

Therefore, as for a direct exposure from the "Chernobyl" radionuclide as such, without taking account of the social and psychological effects, a conclusion can be made that the existing legislation, regulating the protection of the contaminated areas' population, is excessive.

During the period after the Chernobyl accident, considerable political changes took place in Ukraine. The accident happened when Ukraine was a part of the Soviet Union, and any information on the disaster available to the population was strictly limited by the top authorities. This had a number of negative consequences. For example, no iodine prophylaxis was performed in villages situated in the 30 km zone, the consumption of dairy products and fresh green grass and vegetables was restricted (instead of being replaced with clean products).

During the 1990s, after the period of "secrecy", some politicians used to talk about the genocide of the nation, mutants that lived in the Exclusion Zone, etc, especially during the election campaign. This exaggerated a distorted idea of the population and about the evaluation of real risks. Consequently, the majority of the population of Ukraine overestimates the effect of the accident on human health. This belief was also reinforced by the "populist" legislation.

Now one may also hear a lot of rumours about the effect of the accident on human health (for example, about hundreds of thousands of residents of the contaminated areas that are supposed to have died of exposure).

It is obvious for any competent person, that it is impossible to clearly identify the "Chernobyl" component in the situation of general deterioration of the population health due to a group of reasons related to the economic crisis and, consequently, the poverty of the significant part of the population - pollution of the environment with pesticides, heavy metals and other toxic substances, deterioration of the health care quality, etc. The summarised experience of the scientific studies of radiation accidents, the use of irradiation in medicine, etc, have shown so far that no accurate experimental evidence of the negative effect of the irradiation dose of 50 mSv (5 Rem) per year on the health exists. An average individual dose caused by natural irradiation in Ukraine is 5 mSv · year^-1, while in some countries (eg, Finland) it is 8 mSv · year^-1. In some locations individual doses may reach 10 and more mSv · year^-1. It should be remembered that the criterion for the obligatory evacuation is 5 mSv · year^-1.

The lack of knowledge about the emergency irradiation effect on human health has been used by many politicians and is reflected in legislation. This has led to an increase in the psychological stress of residents of the contaminated areas and has undoubtedly affected their health.

The overestimation by the population of risks related to the accident's consequences requires the development of a reasonable approach, including the review of the "Chernobyl" legislation.

It is known that the population’s health in any country on 80-85% depends on the condition of its economy. By "health" we mean physically, psychologically and spiritually favourable conditions and not just the absence of illnesses.

The Chernobyl disaster undoubtedly led to great damage to the economy of the country, namely:

- the direct damage of material objects and electronic objects;

- unproduced electric energy and other indirect losses;

- cost of works related to the liquidation of the accident consequences, instead of use of funds for social development, health care and other purposes.

The general cost of the damage from the Chernobyl disaster (for 1997) is estimated at about 128 billion USD, or 2.1 annual 1997 GDP. These funds could have been used for the development of the economy, scientific research, health care and other areas aimed at the welfare of the country.

3. RISKS RELATED TO OPERATION OF NUCLEAR REACTORS AND THE POSSIBILITY OF THEIR MITIGATION ON THE BASIS OF THE CHERNOBYL EXPERIENCE

In 1996-1997 nuclear power stations produced about 50% of the electric energy in Ukraine. At the same time, the radioactivity in a reactor core equals about 10²⁰ Bq - enough to kill the population of the Earth. The same situation is observed with road accidents that take more lives than any war. Many chemical production plants generate toxic substances dangerous for the life of hundreds of people. Most modern technologies have related risks for the lives and health of people, however, humanity has made its choice to continue the development of a technocratic civilisation. Moreover, this process has positive results, eg, the average life expectancy in developed countries has grown several times.

However, the sources of technological risks require special attention, since this is a part of modern life. The Chernobyl experience is of great value for the understanding of the necessity to create a system of dangerous objects risk management.

The analysis of the reasons for the accident has primarily shown the inadequacy of the nuclear safety infrastructure that was effective at that time. This was taken into consideration and resulted in the establishment of an independent body regulating nuclear and radiation safety in Ukraine – the State Committee on Nuclear and Radiation Safety later reorganised into the Ministry of the Environment and Nuclear Safety.

In addition to the infrastructure, another important element of the safety system is the minimisation of risks in the object through the introduction of several safety barriers, and improved emergency system and other control systems.

An initial construction of the power stations with RBMK reactors failed to ensure appropriate safety criteria.

During 1987-1991 most deficiencies of the construction that had led to the accident were eliminated. A staff training function was improved, and a non-destroying control and safety analysis were provided. Therefore, the same accident scenario appears to be practically impossible at the moment. However, other accidents that may result in a significant release of radioactive substances cannot be excluded.

The Chernobyl accident was a great disaster for the people of Ukraine, however, the residents of Pripiat were lucky to have a northerly, rather than a westerly wind on 26 April 1986, as if the wind had been blowing in the direction of the town, Pripiat might have had significant deterministic exposure effects. This risk, which fortunately did not occur, could have been mitigated, if then and later, the country had had an overall emergency system based on standard response procedures, evaluation of the environment contamination conditions, forecasts and regulation of decisions being made. To establish such a system, the Chernobyl experience may be invaluable.

Emergency preparedness and response is based on prevented expected doses within a short period of time (4-6 hours, a week) and for 50 years (70 years) (TEC 953, TEC955, Po97).

There are three periods of the emergency exposure evaluation: intense (during the release and 4-6 hours later), short term (several days), and long term (up to 50-70 years).

A major task during the intense exposure period of the emergency evaluation is to forecast in which territories the doses may exceed 1 Sv during the release and 4-6 hours after it, thus preventing deterministic 7 effects (SS109).

A main task of the short term period of the emergency evaluation is the following: on the basis of radiation monitoring data, release mitigation measures, personnel and population protection, to forecast the territories where exposure doses will exceed 1 Sv during the next month. At the same time, the evaluation of the dose prevented takes into consideration countermeasures both taken and planned.

A main task of the long-term period is to forecast in what territories irradiation doses may exceed an accepted level during the next 50 (70) years, considering countermeasures taken.

Two last stages of the emergency measures require short term and long term evaluation of appropriate doses according to radiation measurements and computer modelling of the situation.

A great experience in the creation of methods for post-accident radiation monitoring of the environment has been accumulated after the Chernobyl accident. These methods are the basis of the scientific research system for decision making in the event of nuclear and radiation accidents. The creation of such a system based on procedures for the evaluation and monitoring of accidents unified at the regional and international level, is most important. This will be a good example of a positive input in the development of the society of the Chernobyl disaster that brought so much trouble and suffering to people.

Taking into consideration these Chernobyl lessons at national and international level, an overall early warning system needs to be developed to minimise both objective and subjective risks resulting from major accidents.

The elements of this system are:

- education of employees of governmental and legislative bodies, mass media, students and schoolchildren, and the population in general on different types of accidents and disasters, ways and means for collective and individual protection;

- the development of decision-making and models of optimal action system for governmental and legislative bodies, state institutions, governmental and public organisations and mass media in pre-accidental, accidental and post-accidental emergency situations;

- studies of the formation of a subjective opinion on the irradiation effect in order to control this process and minimise its negative consequences for human health;

- spiritual rehabilitation of the population on the way to investment in polluted regions and economy and demonstration of the possibility of normal life.

Open Partial Agreement on the prevention of, protection against, and organisation of relief in major natural and technological disasters jointly with the Ukrainian Ministry of Emergencies and the Ministry of Affairs for Population Protection from the Consequences of Chernobyl Catastrophe have created the organisation "European Centre of Technogenic Safety (TESEC)". One of the TESEC activities is research on the consequences of the Chernobyl NPP accident.

TESEC prepared an annual report for Ministries, "National program of minimisation of Chernobyl catastrophe consequences - implementation". Other projects on the "Chernobyl subject" are also carried out by TESEC.

In the context of a new stage of the development of the liquidation of the accident's consequences we think that it will be expedient to use the common Council of Europe/European Union organisation as a tool for the effective embedding of European Union assistance and to entrust TESEC with carrying out the project "Risk assessment of the Chernobyl accident consequences and efficiency evaluation of countermeasures".