Recovery of the nuclear accident area and cleaning supplies has resulted in a large amount of radioactive waste and contaminated equipment. The nuclear waste generated is found stored at nearly 800 different sites in and outside the 30 km exclusion zone around Chernobyl Nuclear Reactor 4.
These nuclear residues are partially stored in containers or buried in trenches, which can cause risk of contamination of groundwater.
The sarcophagus and the proliferation of waste storage sites have been assessed to represent a source of dangerous radioactivity in nearby areas. Some NEA experts feared that the sinking of the crashed nuclear reactor would cause serious damage to the only operating reactor until December 15, 2000, reactor 3.
The following images correspond to the aspect of neglect that the city of Prypyat currently has, the city closest to the nuclear power plant.
Vienna International Conference
At the Vienna International Conference, held in April 1996, it was concluded that full rehabilitation of the area was not possible due to the existence of contamination "hot spots", risks of groundwater contamination, food restrictions and risks associated with the possible collapse of the sarcophagus, given its deterioration in the years following the accident.
At the Vienna International Conference, it was pointed out that a comprehensive research program was necessary to develop a suitable design that would constitute an ecologically safe containment system. The new confinement of the plant should prevent rainwater seepage inside it and prevent the existing sarcophagus from sinking. The sinking of the current sarcophagus would cause radioactive dust and the remains of nuclear fuel (uranium and plutonium) to escape into the environment.
International aid programs to improve the current situation in Chernobyl
Faced with the Chernobyl situation, the authorities and the nuclear industry in western countries are making notable efforts to help eastern countries improve the safety of their reactors, including RMBKs. Currently it is stated that the situation in these countries is much better than in 1986.
Among the aid programs of the European Union, the programs TACIS (1989) and PHARE (1990) stand out. All financial contributions are transferred to a fund managed by the EBRD (European Bank for Reconstruction and Development) known as the “Chernobyl Shelter Fund (CSF)” or “ Chernobyl Protection Fund”. The EBRD will administer the fund on behalf of the contributing and donor countries, being responsible to the Assembly that meets 3 or 4 times a year. It currently has 22 members, including the European Union and Ukraine.
The TACIS Program financed, in 1996, a first study with the objective of analyzing, in an initial phase, possible short and long-term measures to remedy the deplorable situation of the sarcophagus, and finally transform it into a safe location.
Initially, there were two alternatives: burying the sarcophagus in a concrete block and constructing a new enclosure that would completely cover the damaged Reactor 4 and Reactor 3.
In May 1997, a group of European, American and Japanese experts, funded by the program, prepared the SIP (Shelter Implementation Plan - Protection System Execution Plan). The objectives of the plan to convert the sarcophagus into a safe location were as follows:
- Reduce the risk of subsidence of the sarcophagus.
- In case of sinking, limit the consequences.
- Improve the nuclear safety of the sarcophagus.
- Improve worker safety and environmental protection in the sarcophagus.
- Convert the sarcophagus site into an environmentally safe area.
In addition, the SIP established three milestones to achieve:
- Strategic decision to follow regarding stability and protection.
- Strategy to follow regarding the problem of damaged fuel and scattered inside the sarcophagus.
- Decision of the new type of enclosure to build.
According to the program, the project was to be completed in 2007. Until May 2001, stabilization tasks and other short-term measures were carried out, constituting the first phase of the SIP.
The necessary preliminary technical studies were also carried out to determine a strategy for improving the nuclear plant's security systems and to prepare, in a second phase, the sarcophagus as a safe location.
Regarding the type of protection enclosure, it was finally decided to build a wide metal vault arch inside which unit 4 would be damaged. This construction offered many advantages in terms of reduced irradiation doses, safety during construction, the release of existing unstable structures, more space for decommissioning and the flexibility required to cope with uncertainties of fuel removal. nuclear damaged and scattered.
This metallic vaulted arch was under construction from 2002 and 2005, at a cost of $ 700 million. The sarcophagus will house the units of Nuclear Reactors 3 and 4 of the Chernobyl Nuclear Power Plant, under its internally pressurized double-walled waterproof wall and with a 27-meter deep foundation.
Unit 3 of the Chernobyl plant was permanently shut down on December 15, 2000. Both Ukrainian and foreign experts set the cost of the closure at $ 2 billion to $ 5 billion, until the remaining radioactive fuel was removed from the plant with a 2008 deadline. This decision completed the complete closure of the nuclear installation that had led, on April 26, 1986, to the greatest nuclear catastrophe in the history of nuclear energy.