The following problems related to the destroyed 4th Unit of the
Chernobyl Nuclear Power Plant (NPP) are considered.
Monitoring of the unit's current state, including:
1) Monitoring of the atmospheric release of radioactive elements in
the form of aerosols. In this case the problem is the unqualified
area of cracks and holes that have formed in the “Sarcophagus” (the
“Shelter”) since 1986. In addition, the method used to evaluate the
release, in which an uncontrolled escape of radioactive
contamination is possible, raises objections;
2) Monitoring of the aquatic medium both inside the “Shelter” and on
the industrial site. At present, the quantity of water in the
4th Unit is about 3000 m, which in fact is low- and
intermediate-level radioactive waste. This quantity is not constant
and essentially varies depending on the season, amount of
atmospheric precipitation, the intensity of dust suppression, etc.
In this case the problem is that the paths of water migration
inside the unit are not known, so that an uncontrolled penetration
of water into the ground, via the damaged foundation slab or the
unit's walls, is quite possible;
3) Monitoring of the state of lava-like fuel-containing masses (LFCM)
and the fuel. The problem is that the exact location of the fuel in
the 4th Unit, the amount of fuel in major aggregates of
LFCM, and the nuclear safety of these aggregates are all unknown to
date.
The arrangements for the stabilization of the 4th Unit first of
all include the reinforcement of the structural construction.
The transformation of the “Shelter” into an ecologically safe system is
subject to many questions still unresolved. In particular:
Whether to create a common “Shelter-2” for the 3r and
4th Units or to merely encase the destroyed
4th Unit in concrete (the project “Cube”);
Whether to peace a plant for conditioning and reprocessing of
radioactive waste under the roof of the “Shelter-2”, or to build
this plant separately;
Where to create a temporary repository for containers of
radioactive waste from the ChNPP 4th Unit;
How to solve the problem of radioactive waste permanent storage in
the territory of the Ukraine with proper observation of all nuclear
and radiation safety requirements