10. MAJOR CONCLUSIONS

10.1. INTRODUCTION

Detailed conclusions on each of the major topics are presented at the end of each section. This section lists the more important conclusions for each topic and the final classification of hot spots. Section 11 gives recommendations for the SAP and NAPs.

10.2. CHERNOBYL AFFECTED AREAS

(1)High levels of radioactivity remain within the CEZ. Important hot spots within this zone are the floodplain along the Pripyat River, the Chernobyl nuclear power plant cooling pond and the Chernobyl shelter.

(2)There is still transboundary transfer of radionuclides (mainly 90Sr) by rivers within the Dnieper River basin. The most important source is the floodplain of the Pripyat River within the CEZ.

(3)The concentrations of 137Cs and 90Sr in river waters of the Dnieper River basin have decreased significantly and are now below the maximum permissible levels set by the national authorities and recommended by expert international organizations. Almost all the 137Cs washed out of contaminated areas is immobilized in bottom sediments within the reservoirs of the Dnieper River. The impact of these sediments is low and will decline further with decay and further deposition of sediments on top of the contaminated sediments.

(4)Lakes with no regular outflows still present a radiological problem arising from higher levels of 137Cs in water and fish.

(5)The levels of radioactivity in forest foods (wild game, mushrooms, berries) in some Chernobyl affected areas are above permissible levels, as are those in milk and beef produced by cattle grazing on contaminated floodplains.

10.3. NUCLEAR POWER PLANTS

(6)Routine discharges from nuclear power plants in the Russian Federation and Ukraine are

generally well below authorized limits and do not contribute to significant contamination of the environment.

(7)A legislative and regulatory basis established in both the Russian Federation and Ukraine ensures that all nuclear power plants operate with a valid licence. A legal mechanism exists for regulatory body review and assessment of plant safety and renewal of plant licences on a regular basis.

(8)In recent years the safety of RBMK and WWER reactors has been subject to considerable regulatory and international scrutiny. Major engineering upgrades have been undertaken to improve safety. An international in-depth safety assessment process is under way to optimize the improvement programmes. There is room for improvement in emergency preparedness and response.

10.4. URANIUM MINING AND MILLING

(9)Uranium mining and milling in Ukraine has had a negative impact on the environment. The most serious problem is caused by about 100 × 106 t of tailings and other radioactive waste from past and current operations. Most of the tailings dumps have not been properly rehabilitated and will pose a long term problem unless they are properly stabilized. Tailings D at Dniprodzerzhinsk is considered to have the greatest potential for pollution of the environment because of its proximity to the Dnieper River, the evidence of current seepage and the possibility of catastrophic failure of the impoundment. The situation in the region of tailings C and adjacent to it needs regular control, and decisions on further use should be taken with regard to IAEA recommendations and on the basis of a cost– benefit analysis.

(10)There is a paucity of data on the levels of radionuclides in the vicinity of uranium mines and mills and radioactive waste impoundments. Consequently, it is not possible to estimate the current or future dose rates from these sources with any degree of accuracy.

180

(11)There is a need to urgently start the development of modern standards on the protection of the environment, radiation safety and monitoring in the zone of influence of the uranium sites, consistent with the requirements of Ukrainian law and the recommendations of international organizations such as the IAEA.

10.5. OTHER RADIOLOGICAL SOURCES

(12)Medical and industrial uses of radioisotopes do not pose significant risks to the population of the Dnieper River basin. Radioactive sources with a high radioactivity could be a source of local exposure. Regulatory authorities should ensure that they are properly licensed and managed.

(13)There are many disposal or temporary storage sites for Chernobyl waste in Belarus, the Russian Federation and Ukraine. There is a need to continue to monitor and characterize the most hazardous of these sites; however, their impact appears to be quite localized and does not represent a major source of contamination of surface waters.

(14)There are two RADON type waste storage facilities at Kiev and Dnipropetrovsk in the Ukrainian section of the Dnieper River basin. Further safety assessments need to be undertaken to assess their environmental impact.

(15)The Ecores State facility near Minsk does not comply with international standards for the storage or disposal of radioactive waste. This facility is a potential source of radioactive contamination of the local population, but not of the Dnieper River basin as a whole.

10.6. HUMAN EXPOSURE TO RADIATION

(16) The average dose rate to Ukrainian citizens from natural radiation sources is about 2.5 mSv/a, which is close to the global average. This value is also considered to be a reasonable estimate of the average dose rate to the population of the Dnieper River basin as a whole.

(17)The inhabitants of areas contaminated with radionuclides from the Chernobyl accident in 1986 are still being subjected both to external

exposure from 137Cs gamma radiation and to internal exposure due to consumption of local foodstuffs containing 137Cs and, to a lesser extent, 90Sr. The most important factors controlling the mean external dose are the settlement type (rural or urban) and the level of 137Cs soil deposition (in kBq/m2). For internal exposures, the most important factors are the soil type and the level of 137Cs soil deposition. On average, effective doses to the inhabitants of rural settlements are higher than those to urban dwellers.

(18)The average total annual doses to the inhabitants of settlements located in the Chernobyl accident areas, caused by environmental 137Cs and 90Sr, range from 0.1 to about 5 mSv. In many tens of settlements the average annual exposure level still exceeds the national action level of 1 mSv.

(19)Dosimetric models have been developed and tested to estimate past, present and future radiation exposures from all Chernobyl related pathways. The models predict that, by 2001, people in affected areas had already received at least 75% of their lifetime internal dose due to 137Cs, 134Cs, 90Sr and 89Sr in Chernobyl fallout. Dose rates will decrease slowly with time over the next 50 years as deposited 137Cs (half-life 30 years) decays and is made less available by soil redistribution processes.

(20)For critical groups in Chernobyl contaminated areas, wild foods (e.g. forest mushrooms, game, forest berries and fish) can make an important contribution to dose; for example, in one study in the Bryansk region of the Russian Federation, ‘natural’ foods contributed from 50% to 80% of 137Cs intake. The average annual internal dose due to 137Cs was estimated to be 1.2 mSv for men and 0.7 mSv for women.

(21)In most cases, aquatic pathways (drinking water, fish consumption and irrigation) make only a small contribution to the total dose from Chernobyl sources. At times of flooding of the Pripyat floodplain, dose rates increase somewhat due to washout of 90Sr. Furthermore, in some closed lakes the concentration of 137Cs remains high, and high levels of contamination are found in fish species. People who illegally catch and eat contaminated fish may receive internal doses in excess of 1 mSv/a from this source.

181

(22)Routine releases of radionuclides from operating nuclear reactors in the Dnieper River basin do not contribute significantly to radiation exposure of communities living in their vicinity.

(23)More data are required in order to make reliable estimates of exposures of people living in uranium affected areas. Estimates of exposure from the drinking water pathway suggest low dose rates, except in small areas that are unlikely sources of drinking water.

(24)Further work is needed to assess the potential short term and long term doses that might be received if uranium tailings impoundments adjacent to waterways in Ukraine were to fail and release tailings and/or contaminated water into adjacent rivers.

10.7. GENERAL

(25)Monitoring data are collected by various agencies for different purposes; different methodologies are used, some of which are outdated. There needs to be harmonization of results between the various organizations engaged in monitoring.

10.7.1. Classification of hot spots

Definitions appropriate to radiological assessment have been determined for hot spots, transboundary hot spots, national hot spots and local hot spots. Based on these definitions and assessments by the project team, the following hot spots have been identified.

Actual hot spots:

(a)The Pripyat floodplain area within the CEZ. This is assessed to be a transboundary hot spot

with a current impact and a greater impact during times of high flooding.

(b)The radioactive waste dumps on the former Prydniprovsky chemical plant site in Dniprodzerzhinsk and of the uranium processing operations in Zhovti Vody. These are actual national hot spots with a potential for a major impact over a very long period if impoundment structures erode or fail catastrophically.

(c)Inhabited areas in the three countries with high levels of Chernobyl caused radioactive contamination, including closed lakes in which concentrations of 137Cs in fish or drinking water exceed the permissible levels. These are local hot spots but occur in all three countries.

Potential hot spots:

(i)The Chernobyl shelter in the event of its collapse (transboundary hot spot).

(ii)The Chernobyl cooling pond in the event of a dam failure (national hot spot).

(iii)The Ecores and RADON facilities at Kiev and Dnipropetrovsk, until reconstruction is complete (local hot spots).

10.8. POSSIBLE ACCIDENTS

In addition to these actual and potential hot spots, an accident at a nuclear power plant was considered. A major accident at a nuclear power plant is considered to be of very low probability, having regard for major and ongoing improvements at nuclear power plants in the Russian Federation and Ukraine. However, a large release would have considerable transboundary impacts, especially in the Black Sea if the source were in the south of Ukraine.

182

11. RECOMMENDATIONS TO THE GOVERNMENTS

OF BELARUS, THE RUSSIAN FEDERATION AND UKRAINE

FOR THE STRATEGIC ACTION PLAN

AND NATIONAL ACTION PLANS

11.1.CHERNOBYL AFFECTED AREAS

Within the CEZ:

(1)The engineering works on the right bank of the Pripyat river within the CEZ should be completed. The works were started in 1998 but

were suspended due to lack of funding.

(1)A diversionary canal should be constructed along the Belarus–Ukraine border between the settlements of Krasne and Zimovische to prevent inundation of the heavily contaminated areas on the Pripyat River’s left bank.

(2)After 2007 the heavily contaminated Chernobyl cooling pond should be safely decommissioned.

(3)Appropriate measures need to be taken to monitor and prevent releases of radioactivity from the Chernobyl shelter.

(4)Technical measures should be taken to prevent significant radionuclide dispersion from the sites of temporary radioactive waste storage in the floodplain of the Pripyat River.

(5)The monitoring system for surface and underground waters in the CEZ should be improved and optimized.

Within inhabited areas:

(6)In order to reduce population exposure in the most contaminated areas, the following measures should be considered:

(i)Restrict consumption of local foods (wild game, fish, berries, mushrooms, etc.);

(ii)Restrict grazing and use of vegetation on floodplains;

(iii)Provide safe water to rural communities.

(7)The monitoring system for surface and underground waters should be optimized. In particular, screening studies on closed lakes in the most contaminated areas should be performed and their impact on population exposure assessed.

(8)The radiological criteria in the Chernobyl affected countries should be harmonized.

11.2. NUCLEAR POWER PLANTS

(9)Rules and regulations should be harmonized within the Dnieper River basin and made consistent with international best practice.

(10)Cooperation and information exchange between regulatory organizations should be strengthened to make use of experience gained in implementing safety upgrade programmes.

(11)To improve preparedness for a possible nuclear accident, technical measures (early warning systems, decision support systems), institutional measures (logistics) and links between nuclear power plants and regional administrative units should be improved.

(12)The scope of safety analysis reports should be compliant with national requirements and consistent with the IAEA safety standards and current international practice.

(13)Comprehensive plant specific probabilistic safety assessments need to be finalized for all nuclear power plants in the region and subjected to thorough regulatory review. The countries with nuclear power plants would benefit from participation in activities organized by the IAEA on comparison of probabilistic safety assessment studies for similar reactors.

(14)Plans established for safety improvements should be carried out as a matter of urgency.

11.3. URANIUM MINING AND PROCESSING

(15)An ongoing system for radioecological monitoring of the environment (water, soil, vegetation, air and food products) in the affected regions (Zhovti Vody, mining areas

and Dniprodzerzhinsk) needs to be

183