Pripyat Blog

Shelter object. Current status

Actually it is possible to consider as established, that inside the Shelter object remains about 90% of fuel, which was in a reactor at the moment of accident. Its total activity makes about 18 mln curies. Destructive processes, occurring in fuel containing materials (FCM), every year increase their hazard. Lava-like FCM destructs spontaneously and radionuclides containing in them are transformed from the bound state in mobile dust particles capable to live the Shelter boundaries with air flows. The radioactive dust amount according to conservative estimations makes about 4 tons.

There is a potential risk of a radioactive dust releases in an environment during probable collapse of supporting constructions, and due to water migration.
At the site near the Shelter under the layer of the ground, sand and concrete there is significant quantity of radioactive substances, non-isolated from hydrogeological environment.

Object’s constructions don’t meet the requirements of the normative and technical documentation on Safety if the field of mechanical durability, structural integrity, constructive reliability and have undetermined operational term.

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Started during the first days after the accident complex diagnostic investigations were continued after Shelter object construction completion. Main arias of investigations were:
• сlarification of quantity and location of nuclear fuel inside the Unit;
• determination of fuel containing masses mechanical, physical and chemical condition;
• nuclear and radiation safety assessment;
• creation and operation of diagnostic systems;
• facility’s constructions reliability monitoring.
Investigation of the Shelter object started from hols drilling. Results of these investigations provided wide volume of information. It was possible to determine character of internal damages, constructions condition, to penetrate to fuel congestions and to sample fuel containing materials (FCM), to measure directly neutron multiplication factor in congestions, which showed that FCM in the Shelter were in subcritical state. It was established, that inside the Shelter the fuel was in the form of destroyed reactor core fragments, stark glassy mass (lava) and fuel dust.
Results of drilling allowed to determine new penetration ways into the Shelter premises and stimulated creation of the special diagnostic robots for works implementation inside the sarcophagus.

Initial large-scale works on Shelter’s constructions reinforcement were started in 1987 and completed in 1989. It was revealed three zones requiring urgent anti-emergency measures: deaerator stack, main circulating pumps premise and premise 805/3.
In spit of additional measures on constructions reinforcement, experts understood, that in existing status the Shelter couldn’t be considered as facility, safety of which is ensured for decades.
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