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Information to the 30th anniversary of the Chernobyl disaster
14 March 2016 12:07

Chernobyl NPP

 

State Specialized EnterpriseChernobyl NPP” (SSE ChNPP) was established based on Chernobyl NPP in accordance with the Decree No.1084/2000 of the President of Ukraine dated September 25, 2000, “On Actions Associated with an Act of Chernobyl Nuclear Power Plant Shutdown” and the Order No.399 of the Cabinet of Ministers of Ukraine dated April 25, 2001, “On Establishment of the State Specialized Enterprise “Chernobyl NPP”.

SSE ChNPP is based on government property and funded at the costs of the State Budget. Planning and organization of works at the Stage of ChNPP Shutdown is currently carried out in accordance with the National Program of Chernobyl NPP Decommissioning and the Shelter Transformation into Environmentally Safe System which became effective since January 1, 2010.

 

Basic tasks of the enterprise:

Performance of Units 1, 2, 3 shutdown programs;

Performance of Units 1, 2, 3 decommissioning programs;

Safe current operation of shut-down Units and Shelter facility;

Performance of the Shelter Implementation Plan regarding its transformation into environmentally safe system.

SSE ChNPP is an operating organization (operator) of nuclear facilities of this NPP at the stage of their decommissioning and elimination of the beyond-design-basis accident consequences, as well as of radioactive waste management facilities and temporary waste storage facilities pursuant to effective legislation of Ukraine.

The Chernobyl NPP consists of three power units containing reactor installations of RBMK-1000 type:

Unit 1 was shut down on November 30, 1996.

The reactor installation was brought into a condition of “finally shut-down”.

On September 28, 2013, the activities on Unit 1 release from conditioned spent nuclear fuel were completed.

Unit 2 was shut down on October 11, 1991, due to a fire occurred in the Turbine Hall. The reactor installation was brought into a condition of “finally shut-down”.

On November 30, 2012, the activities on Unit 2 release from conditioned spent nuclear fuel were completed.

Unit 3 was shut down on December 15, 2000, according to the Order of the Cabinet of Ministers of Ukraine “On Pre-schedule Shutdown of Unit 3 and Final Shutdown of Chernobyl NPP”.

The reactor installation was brought into a condition of “finally shut-down”.

In December 2012, Unit 3 status was changed. By a decision agreed with the State Nuclear Regulatory Inspectorate of Ukraine, it was recognized as the radioactive waste management facility.

Besides the Units, the Chernobyl NPP includes Shelter Object as well, i.e. an engineering building ensuring containment of Unit 4 destroyed as consequence of beyond-design-basis accident, Interim Storage Facilities for Spent Nuclear Fuel, Startup Auxiliary Heating Plant, Cooling Pond, the plants for liquid and solid RAW processing and other infrastructure facilities.

The shut-down Chernobyl NPP remains the nuclear facility. Relating to safety, it continues to be in the same legal and regulatory framework as the operating nuclear power plants.

Safety within Chernobyl NPP site is of the highest priority. Notwithstanding the ChNPP Units are shut down and don’t generate electric power, they continue to be nuclear and radiation hazardous facilities. To preserve the achieved level of safety at ChNPP, a number of measures are being carried out relating to keeping the power units in safe condition:

-       Safety-related systems and process control systems are kept in operating condition and tested in accordance with the requirements of regulatory and technical documentation;

-       Operation of systems and equipment is carried out in strict accordance with the requirements of regulations and manufacturer’s instructions;

-       A required temperature and humidity condition is maintained within buildings and structures;

-       Maintenance and scheduled repairs of equipment are performed with periodicity prescribed by the regulatory and technical documentation;

-       Fire prevention regime is established and supported within enterprise’s area;

-       Corresponding sanitary-access regime is established as barrier system on the ways of potential carry-over of radionuclides beyond boundaries of the enterprise and Exclusion Zone;

-       Activity regarding personnel training and advanced training is carried out continuously.

 

 

Chernobyl NPP. Decommissioning

 

The available world experience shows that NPP decommissioning is a complex and long-term process that requires development of regulatory-legal and technical documentation, production of specific-purpose equipment, long-term preparation and significant labour and material resources.

Taking into account international and national experience, regulatory framework of Ukraine and actual state of the site, the ChNPP decommissioning is performed under following stages:

1. Shutdown (preparatory stage prior to decommissioning) is a stage during which nuclear fuel will be removed and transferred to a storage facility for spent nuclear fuel intended for long-term storage. Completion term is not before 2014.

2. Final Shutdown and Preservation of reactor facilities/installations. During this stage, the reactors and the most radioactively contaminated equipment will be preserved (approximately, till 2028).

3. Safe enclosure of reactor facilities within the period, during which radioactive radiation should be naturally decreased to an acceptable level (approximately, till 2045).

4. Dismantling of reactor facilities, during which the hardware will be dismantled and the site will be decontaminated with a purpose of removing restrictions to the maximum and regulatory control (approximately, till 2065).

According to the requirements of General Provisions of safety assurance during decommissioning of nuclear power plants and research nuclear reactors during ChNPP decommissioning, the following tasks should be implemented:

1. Safety assurance during decommissioning of Units 1, 2, 3;

2. Protection of personnel, public and environment from hazardous impact of ionizing radiation and protection of future generations;

3. Bringing the Units 1, 2, 3 to a condition excluding a potential of further use of these energy facilities with the purposes for which they were constructed.

4. Performance of a number of actions to achieve the conditions, within the area of Units 1, 2, 3 and auxiliary structures location, which maximally lift restrictions for using this area. This envisages:

- gradual release from ionizing radiation sources subject to control;

- cancellation of restriction conditions and reduction of radiation monitoring within observation area and sanitary-protective area of ChNPP.

According to the results of a comprehensive consideration of options under the principle “expenses – benefit”, a “deferred dismantling” decommissioning strategy is accepted for ChNPP Units (under international classification – SAFSTOR method), which envisages long-term safe enclosure of the structures of reactors and equipment of primary circuit – up to 50 years at the available reinforced concrete building structures with early removal of process channels and performance of dismantling activities and further decontamination of external equipment.

The selected dismantling strategy set in the Chernobyl NPP Decommissioning Program specifies ability of dismantling at the stage of shutdown of facility systems and components being external to nuclear reactor, which are not safety-related and not required for work during subsequent decommissioning stages, under the principle “from clean equipment to contaminated one”, from viewpoint of its radioactivity. Since February 2012, the activities relating to dismantling of equipment and structural components are being carried out, as well as its fragmentation, decontamination and release from regulatory control.

Dismantling of building structures and clearance of ChNPP site area do not belong to decommissioning activity and will be considered under framework of minimization of accident consequences and rehabilitation of the Exclusion Zone.

Decommissioning of ChNPP requires simultaneous performance of works on preparation for decommissioning and decommissioning of the Units, including construction of required facilities relating to management of spent nuclear fuel and radioactive waste (RAW), introduction of new technologies and equipment, development of necessary regulatory-technical, design and operational documentation, etc.

 

 

Current state of the Shelter Object

 

The Shelter Object is a set of structures formed of damaged structures of Unit 4 and newly constructed structures and system following the accident intended to control and manage post-accident situation.

By a decision of the state regulatory authority for nuclear and radiation safety, the Shelter facility is defined as destroyed by beyond-design-basis accident Unit 4, where top-priority actions have been implemented regarding elimination of accident consequences and ensuring control of its condition.

Peculiarities of the Shelter are defined by its potential hazard, which is much higher than standards and regulations permit for the facilities containing nuclear and radioactive materials, and by a lack of practice for operation of such or similar facility.

Potential hazard of the Shelter for environment and human is determined by following factors:

Presence of nuclear materials at the quantity of about 200 tons, for which there are no measures of active influence to their criticality, and absence of reliable physical barriers on the way of radioactivity spreading into the environment.

Inside the Shelter, about 95% of fuel remained, which was within the reactor at the moment of accident occurrence. Destructive processes taking place in fuel-containing materials (FCM) increase their hazard year by year. Lava-like FCM are self-destroyed and radionuclides contained in them are passed from fixed state into moveable dust particles able to get outside the Shelter boundaries with air flows. Currently, by conservative estimates, the amount of radioactive dust is about 1.5 tons.

Water inflow to the Shelter premises is associated with many negative consequences able to destabilize currently achieved level of nuclear, radiation and radioecological safety of the Shelter. Besides, water disturbs normal operation of diagnostic systems, impedes performance of investigations on improving safety of the facility, influences on electrical safety of the Shelter premises.

Building structures of the facility do not meet the requirements of safety-related regulatory and technical documentation regarding mechanical durability, structural integrity, structural reliability and have indefinite period of operation.

Impossibility to ensure full monitoring of the object condition, in particular, the condition of building structures, nuclear and radioactive materials due to the limited access to some rooms which is made more complicated by high radiation level. As consequence of insufficient survey of the object no reliable quantitative assessments of various types of risks have been provided.

Radioactive aerosols of Shelter Object. At the time being, Shelter Object does not have any prominent impact on general radioactive contamination of the ambient air which is predominantly characterised with surface contamination of the adjacent area as result of the 1986 accident.

The whole current and transforming activity at Shelter Object is intended for protection of personnel, residents and environment against impact of radioactive materials located within the object and its industrial site.

Administrative and engineering measures to ensure safety of Shelter Object

  • monitoring SO condition
  • localisation of contamination distribution within SO boundaries
  • prevention of SO safe/normal operation limits violation
  • maintenance of SO systems, equipment and buildings
  • emergency preparedness.

At Shelter Object, combustible and lubricating material condition as well as radionuclide composition of air, water and air flow are monitored (about 20, 000 samples annually), also the monitoring of building structure condition and  process radiation monitoring are provided.

In order to localise radioactivity within SO, the ChNPP’s personnel provide on daily basis decontamination and dust suppression of premises and areas of SO local zone as well as of the areas where activities are carried out. Continuously, in the course of radioactive waste generating and receipt, the radioactive waste is collected and removed for disposal or interim storing.

 

 

Shelter Object. Transformation

 

Within the framework of TACIS project "Chernobyl Unit 4. Short- and long-term measures - Measures 2 + 4" in 1996 “Recommended Course of Actions” was developed in which potential short- and long-term measures were proposed to be determined as well as the comprehensive set of top priority measures for Shelter Object transforming into ecologically safe system. “Recommended Course of Actions” specifies the main concept including a package of steps towards transformation of Shelter Object into a safe system. With purpose to implement the recommended course of actions, Ukraine developed “Strategy of Shelter Object Transformation”. In accordance with this document, transformation of Shelter Object into ecologically safe system is completed via three main phases:

Phase 1: stabilization of existing object status, enhancing operational reliability and durability of constructions and systems which ensure stabilization and monitoring of Shelter safety indicators.

Phase 2: creation of the additional protective barriers (New Safe Confinement first of all) that will provide necessary conditions for engineering activity at Phase 3 and safety of the personnel, population and environment; the preparatory engineering works aimed at development of the technologies for Fuel Containing Materials removal from SO at Phase 3; infrastructure creation for Shelter Object’s RAW management.

Phase 3: fuel containing materials and long lived RAW retrieval from SO, their conditioning with the subsequent storage and disposal in RAW storage facility according to the effective standards, Shelter Object decommissioning.

The main SIP project is construction of New Safe Confinement. It is a multi-purpose complex for transformation of Shelter Object into ecologically safe system. It encompasses a main building including arch-shaped structure, foundations, west and east side walls (essential sustaining) and ancillary systems; a process building with decontamination, fragmentation and packing areas, sanitary barriers, workshops and other process compartments; auxiliary buildings.

On September 17, 2007, upon completion of an open international tender, SSE CHNPP and Consortium “NOVARKA” signed a contract for design, construction and commissioning of New Safe Confinement.

New Safe Confinement as a multi-purpose complex with 100-year service life will enable in the future to dismantle the unstable structures of the existent Shelter, to remove fuel containing materials, to provide their conditioning for further safe storage.

 

New Safe Confinement (NSC)

 

Engineer: Project Management Unit (PMU) - Bechtel (USA) – Bettelle Memorial (USA) - SSE ChNPP

Contractor (Design-Procurement-Construction): Joint Venture NOVARKA, France (VINCI Construction Grands Projets - 50% / Bouygues Travaux Publics - 50%)

Funding: Chernobyl Shelter Fund (CSF)

Contract signing date: August 10, 2007.

Contract completion date: November 30, 2017.

New Safe Confinement is a multi-purpose complex for transformation of Shelter Object into an ecologically safe system. Based on the design, NSC comprises:

- a main building including: arch-shaped structure whose north-south span makes 257.44 m, height makes 108.39 m, length makes 150 m; foundations, west and east side ends (essential sustaining) and ancillary systems;

- a process building encompassing decontamination, fragmentation and packing areas, sanitary barriers, workshops and other process compartments;

- auxiliary buildings.

Design-based service life of NSC is 100 years.

At the construction FIRST PHASE commencing in 2008 and actually completed, the preparatory activities were performed enabling safe and efficient construction of NSC. Particularly, a large scope of works was completed associated with clearing and planning of the area, arrangement of foundation pits for construction of the foundations for assembly, transport and service areas of NSC, and mounting site for assembly of the Arch’s structures to major units.

At the SECOND PHASE, the design and NSC construction are being carried out as well as the whole package of comprehensive testing and its commissioning.

At the THIRD PHASE, upon commissioning of Start-up Package-2 and ProcessBuilding as a part of integrated RAW management system at ChNPP industrial site, it is possible to commence early dismantling of SO unstable structures to the extent specified at the stage of relevant detailed design. Early dismantling activities and management of dismantled structures and associated RAW will be performed using process lines located within the ProcessBuilding.

 

 

Decommissioning Projects

 

In the framework of international technical aid projects with partial funding by Ukraine, some facilities have been built and are being built within ChNPP industrial site. These facilities are essential for Chernobyl NPP Units decommissioning, namely:

Spent Fuel Interim Storage Facility (ISF-2)

ISF-2 is intended for acceptance, preparation for storage and storage of Spent Fuel Assemblies (SAF) accumulated in the course of Chernobyl NPP operation.

ISF-2 will provide acceptance for storage, preparation for storage and storage within 100 years of more than 21,000 RBMK-1000 SFAs with throughput of 2,500 SFA per year.

Liquid Radwaste Treatment Plant (LRTP)

LRTP is designed for treatment of liquid radioactive waste accumulated during operation and those generated during ChNPP decommissioning, and operational liquid RAW of Shelter Object.

Its designed capacity is the following:

- treatment of incoming product is 2,500 m3 per year;

- final product makes 10,000 drums per year;

- total designed capacity makes 250,000 drums per year.

 

Industrial Complex for Solid Radioactive Waste Management (ICSRM)

ICSRM is designed for acceptance, treatment and/or disposal of solid RAW accumulated during the operation period and those generated during ChNPP decommissioning, and operational solid RAW of Shelter Object.

Complex comprises four interlinked facilities:

- Temporary storage facility for low- and intermediate level long-lived waste and high-level waste.

- Facility for removal of all-type solid radioactive waste from the existing waste storage facility. Capacity is the following: removal makes 3 m3 of RAW per day; operational life cycle is 30 years.

- Plant for sorting all-type solid radioactive waste and processing low- and intermediate-level solid waste. Capacity is 20 m3 of non-treated waste per day; capacity of incineration facility is 50 kg/h (solid RAW), 10 kg/h (liquid RAW); capacity of cementation facility is 10 m3 per day; facility for LIL LLW and HLW packaging is 1.5 m3 per day; capacity of interim storage facility for LIL LLW and HLW is 3,500 m3, operational life cycle is 30 years.

- Engineered near-surface disposal facility for low- and intermediate-level short-lived solid waste.  Capacity is 55,000 m3of waste packages; equipment operation lifetime at the stage of filling is 30 years; state surveillance period of the enclosed disposal facility is 300 years.

 

Complex for Production of Steel Drums and Reinforced Concrete Containers

The Complex as an essential part of safety assurance programme at radioactive waste and spent nuclear fuel management will provide safe collection, moving and handling procedures, storage, processing, transportation and disposal of radioactive waste.

Mainline production capacity makes:
- 34,250 steel drums per year;
- 700 reinforced concrete containers per year.

 

Modernisation of Long-Length Waste Cutting Facility (LLWCF)

The subject of existent long-length waste cutting facility modernisation is establishment of a new line for long-length waste cutting in Unit 2. This line should be portable for its installation in other units. The purpose of this project implementation is safe management of equipment and special items which were used within power-generating units operation in the reactor core. It is also intended for decrease of radiation impact on the personnel as well as for safe removal from ChNPP units of a great number of special items including their highly radioactive pieces. 

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