Current status of the ChEZ
The area of the Chornobyl Exclusion Zone and the Zone of Unconditional (Obligatory) Resettlement (the EZ and ZU(О)R) is 2600 km2.
The EZ and ZU(O)R is a territory with strictly restricted access and movement, which is controlled by a block of special laws and regulations. The status of the EZ and ZU(O)R is determined by the Ukrainian legislation, in particular, by the Law of Ukraine ‘On the Legal Regime of the Territory that was Subjected to the Radioactive Contaminated as a Result of the Chornobyl Accident’. In accordance with the current legislation:
the Exclusion Zone is the territory, from which the evacuation of the population was carried out in 1986;
the Zone of Unconditional (Obligatory) Resettlement is a territory that was subjected to the intense pollution with the long-lived radionuclides, with a density of soil contamination above the pre-accident level of cesium isotopes from 15.0 Ci/km2 and above, or strontium from 3.0 Cі/km2 and above, or plutonium from 0.1 Ci/km2 and above, where the estimated effective equivalent dose of human radiation, taking into account the coefficients of migration of radionuclides in plants and other factors, may exceed 5.0 mSv (0.5 rem) per year above of the dose that was received by a man in the pre-accident period.
Zoning of the Chornobyl Exclusion Zone territory
The Chornobyl Exclusion Zone is divided into the territories taking into account the inequality of radioactive contamination of the area, the location of the radioactive waste temporary storage places and radioactive waste disposal sites, available and planned complexes for the radioactive waste processing and storage, as well as elements of infrastructure, various natural conditions (including the need of conservation of the available protected objects), predictions of changes in the radioecological state of the territory, radiation and hygiene peculiarities, introduction of the special regime regulating all activities, the number of the staff and duration of its stay at the territory. The territory is divided into three radiation and regime zones, where a special sanitary and access control regime is introduced.
Zone I (10 km Zone) is an area within the 10 km radius around the Chornobyl Nuclear Power Plant (ChNPP), where the main work related to the elimination of the Chornobyl accident consequences (radiation-hazardous works) is carried out under the program agreed with the Regulatory Bodies in accordance with the current normative and legal acts on radiation safety of Ukraine. In case of necessity, according to the results of radiation dosimetry control, especially dangerous work is carried out in accordance with the special regulations with the orders and permits. The territory is divided into two parts, different in density and composition of radionuclide pollution and the nature of activity:
- territory of the special danger is a site, where the work is carried out on transformation of the Shelter Object into an environmentally safe system, radioactive waste management, the ChNPP decommissioning, protection of the floodplain of the Pripyat River from flooding during the floods, sanitary and fire protection measures in forests;
- territory of the high danger is a site, where the elements of the production activity and the infrastructure of the EZ and ZU(O)R to provide production activity are concentrated.
At these territories, it is envisaged to introduce various regulations on occupational safety and radiation protection of personnel.
Zone II (buffer) is a territory from the border of the 10 km zone to the external boundary of the Exclusion Zone (except the Chornobyl Town) with a low density of radioactive contamination, which is perspective for returning to the national economic use. This zone is characterized by the limitation of activities. Within its boundaries, it is planned to carry out forest-related activities taking into account the prospect of the return of this territory to the national economic use. Some sites can be used as research and other polygons. The buffer zone includes a protected zone (not less than 10 percent of the natural land). At the territory of the protected zone, a regime is observed that eliminates the disturbance of the natural course of self-recovery of ecosystems by limiting the presence of personnel in accordance with the status of the reserve. The works within this zone are carried out in accordance with monthly schedules.
Zone III (location of the shift personnel) combines part of the territory of the Chornobyl Town, where hostels and administrative buildings are located along with adjacent sites, public catering and trade facilities, social-cultural, medical and sanitary facilities, access roads to them.
The management of the EZ and ZU(O)R is entrusted to the State Department – Administration of the Exclusion Zone and the Zone of Unconditional (Obligatory) Resettlement (SAUEZM).
The main mission of the Chornobyl Exclusion Zone is the protection of the population and personnel from the radioactive contamination, control and limitation of the radiation propagation, implementation of measures for the further elimination of the accident consequences and the permitted industrial activities, as well as support of the ecosystems of the region in the controlled stable condition and assistance in their natural rehabilitation.
Regular radiation and dosimetry monitoring is carried out at the territory and facilities of EZ and ZU(O)R. For the facilities located in each zone, the control levels of radioactive contamination (CL) are approved in the established order. The values of the CL must not exceed 70% of the values of the corresponding allowable levels.
When leaving the boundaries of the EZ and ZU(O)R, the obligatory radiation control of vehicles, shipment and personnel is carried out.
The exposure dose levels at the territory within the 10 km Exclusion Zone are currently 100-200 μR/h, and the density of the soil contamination by radionuclides is from 800 to 8000 kBq/m2 (but may exceed this value). At the territory of the Buffer Zone, the exposure dose rate is from 20 to 200 μR/h, and the density of the soil contamination varies from 20 to 4000 kBq/m2. The rate of contamination by radionuclides for the territories with population is 37 kBq/m2. The main part of the radioactivity is concentrated in the upper layer of soil (5-10 cm) and in the forest litter.