Pripyat Blog

Chernobyl. New safe confinement. Unique graphic materials in 3D technology that show in details building of new safe

confinement.

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Shelter stabilization.

Unique graphic materials in 3D technology that show in details stabilization of existing

sarcophagus.

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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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Shelter Implementation Plan

Shelter Implementation Plan (SIP) became the culmination of the efforts made by Ukraine and International Community toward development of economically and ecologically acceptable approach to resolve the Shelter problems. It was developed under cooperation of European Union Commission, Ukraine, USA and team of international experts and approved in June 1997 at G7 countries meeting.
The main project goal is Shelter object transformation into environmentally safe system with regard to personnel protection, radiological and environmental safety. SIP project consists of stabilization and other urgent measures and regular strategic measures development and implementation for step-by-step Shelter transformation into safe facility. Final SIP goal is new safe confinement (Shelter-2) erection and Shelter object unstable constructions dismantling.
28 Donors countries and European Commission pledged to allocate funds necessary for the project implementation into Chornobyl Shelter Fund (CSF), established according to Memorandum of Understanding and assigned to assist Ukraine in transformation of existing sarcophagus into safe and environmentally stable system by Shelter Implementation Plan realisation. Total cost of works performance according to more precise estimation makes 1091mln US$.
Project implementation
The first phase of the project lasted since 1998 up to mid 2000. That was the stage of investigations, development of strategies, programs, concept designs and preparatory works for the phase 2. In transitional period – since mid 2000 up to the beginning of 2001- the results of the undertaken investigations were reviewed and the program decisions were adopted. More then 30 companies from different countries and a number of key Ukrainian research institutes were involved in the activity within the first phase
Implementation of two emergency stabilization measures of the structure has become a considerable achievement. ChNPP Units 3 and 4 ventilation stack foundation and bracing were repaired in 1998, beams B1/B2, being the basic support for the sarcophagus roof were reinforced in 1999.
Besides the works, which contributed to the Shelter safety improvement and the development of infrastructure were carried out in the frames of the first phase
The second phase of the project implementation started since the beginning of 2001. First of all that was an activity, linked to unstable Shelter structures stabilization, installation and commissioning of monitoring systems, development and testing a technology for FCM removal, implementation of technical decisions on water and dust management, new safe confinement (NSC) construction and dismantling of Shelter unstable structures under a new protective enclosure. At SO and ChNPP site very difficult and, as a rule, unique and technically non-uniform activity has been done during Phase 2 implementation.
New Safe Confinement

New Safe Confinement (NSC) construction above the Shelter object is one of thee most important condition of the Shelter object transformation into ecologically safe system.
Confinement is a protective facility, included a complex of technological equipment for fuel containing materials removal out of the Chernobyl destroyed Unit 4 and for radioactive waste management and other systems, designed to perform the activity on the Unit transformation into environmentally safe site and to provide personnel, residents and environment safety According to Conceptual Design NSC includes:

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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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At 01 hr 23 min 49 sec Moscow time on April 26, 1986, the world’s worst-ever nuclear disaster occurred at Power Generation Unit No.4 of the Chornobyl NPP. As a result, the reactor core was destroyed completely, and almost all its supporting structures were severely damaged. The reactor and its building were destroyed by two powerful explosions. The upper biological shielding of the reactor (scheme “E”) was torn off and turned at 15° to the vertical. All high-pressure pipes were destroyed. Hot graphite blocks, fragments of pipelines and equipment were thrown outside. Most of the debris piled up at the north wall. The explosion destroyed the separator room. All the four separators, each weighing 130 tons, were moved from their supports and torn off from the pipelines.

The roof collapsed and hung down on the separators.
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