Since 1992 an active work on Shelter Object transformation into an ecologically safe system, including those performed under international programs, has been implemented. The main conclusion of this long-term research is that a considerable reduction of Shelter Object’s hazard can be achieved by constructing a new protection structure over the Shelter – that is a New Safe Confinement (NSC).
The necessity of creating the NSC is set forth in the following documents:
- Law of Ukraine “On the general principles of the further Chоrnobyl NPP operation and decommissioning, and transformation of the destroyed 4th Unit of this NPP into an ecologically safe system”;- Shelter Object Transformation Strategy approved by a Decision of a Government Commission on the Issues of Comprehensive Chоrnobyl NPP Problem-Solving;
- Shelter Implementation Plan adopted in June 1997 at the G7 meeting.
In the Law of Ukraine “On the general principles of the further Chоrnobyl NPP operation and decommissioning, and transformation of the destroyed 4th Unit of this NPP into an ecologically safe system” are laid down the basic requirements to the Confinement:
“The Confinement is a protection facility comprising a set of processing equipment for removal of materials containing nuclear fuel from the destroyed Chоrnobyl NPP 4th Unit, radioactive waste management and other systems designed for transforming this Power Unit into an ecologically safe system and ensuring the safety of personnel, public and environment”.
In accordance with the Conceptual Design the NSC includes:
- the main facility comprising the Arch structure, chord of which is 257.44 m towards North-South, height – 108.3 m and length - 150 m;
- foundations, western and eastern end walls, required supporting and auxiliary systems;
- processing building including sections for decontamination, fragmentation and packing, sanitary locks, workshop and other process premises;
- auxiliary structures.
To assure nuclear, radiation and general industrial safety of the NSC facility and its efficient operation involving a minimum number of operating personnel it is envisaged to establish an Integrated NSC Management System.
It will include such systems as:
- Radiation safety monitoring system;
- Seismic monitoring system;
- Monitoring system of building structures state;
- Operation support systems: ventilation, water supply, sewerage (including liquid radioactive waste management) and power-supply systems;
- Process systems for management of radioactive waste and fuel-containing materials.
In addition, fire safety and physical protection systems, communication and TV networks will be installed. Crane equipment will be erected to ensure dismantling of unstable structures.
Main NSC functions:
1. Limit the radiation impact on public, personnel and environment within the established boundaries, both during normal Shelter Object operation and in case of normal-operation disturbances, emergencies and accidents, including accidents occurring during dismantling of unstable structures and future management of fuel-containing materials (FCM) and radioactive waste (RAW).
2. Limit the spread of ionizing radiation and radioactive substances contained within the Shelter Object.
3. Technology process support – i.e. creating conditions for dismantling of unstable structures, future FCM and RAW removal, accumulated water removal, ensuring that measures on monitoring and maintenance of the Shelter Object and its Industrial Site are implemented.
4. Monitor all the Shelter state parameters and manage technology processes.
5. Physical protection – i.e. prevent unauthorized access to FCM and RAW, and ensure functioning of the IAEA safeguards system.
The NSC construction will enable the following to be achieved:
• increased level of radiation safety – the NSC cladding safety would limit radiation impact on public, personnel and environment for 100 years of operation;
• reduced probability of accidental collapse due to dismantling of unstable structures;
• reduced consequences of accidental collapse owning to enclosing and bearing structures, and monitoring systems inside the NSC;
• improved Shelter Object nuclear safety by preventing atmospheric moisture from getting onto FCM accumulations, that considerably reduces the risk of occurring a self-sustained chain reaction;
• ensured implementation of the Shelter transformation strategy owning to durability of the NSC structures, and possibility of dismantling of unstable structures of the existing Shelter Object and removal of fuel-containing materials.
The Safe Confinement as a multifunctional facility with the service life of 100 years in future will enable to remove fuel-containing materials and their conditioning for further safe storage.
The NSC Conceptual Design ordered by ChNPP was developed by a Consortium of Bechtel и Battelle (USA), and EDF (France) involving the Ukrainian “KSK” Consortium (Scientific and Research Institute for Civil Structures (NIISK), Kyiv Institute “EnergoProekt” (KIEP), and Interdisciplinary Scientific and Technical Center “Shelter” (now an Institute for NPP Safety Problems)).
The Conceptual Design was discussed at public hearings held in March 2004 in Slavutych, as well as within Ukrainian scientific circles, and it passed a comprehensive state expert examination. Under the results of these discussions the Cabinet of Ministers of Ukraine approved this Design as a basis for further design work by its Order №443-r dated July 5, 2004.
The Conceptual Design justifies the possibilities to implement the proposed engineering solutions, assesses the ecological NSC efficiency as compared to the existing level of Shelter Object impact on environment, and evaluates terms of construction and financial expenditure required for the NSC creation.
On August 10, 2007, after an open international two-stage tendering, the SSE “Chоrnobyl NPP” and International Consortium NOVARKA comprised of two French companies “VINCI Construction Grands Projets” and “Bouygues Travaux Publics” concluded a contract for designing, construction and commissioning of Commissioning Stage 1 (CS-1) of the New Safe Confinement.