Chernobyl (Ukraine)

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Location of the biggest nuclear accident; since April 1986 heavily contaminated. Site of the sarcophagus containing the destroyed reactor of unit-4 and centre of the exclusion zone, with several radioactive waste dumps. After a severe fire, which destroyed the turbine, unit-2 has been closed, too. Units 3 and 4 have also been shut down.

Facilities in Chernobyl

plantreactor typconstruction startoperation startshut down
Chernobyl-1RBMK 1000197219771996
Chernobyl-2RBMK 1000197319781991
Chernobyl-3RBMK 1000197719812000
Chernobyl-4RBMK 1000197919831986

The Federal Government provides further funding for clean-up work in Chernobyl. Federal Environment Minister Sigmar Gabriel has granted Ukraine a further euro 12.4 million to overcome the consequences of the devastating accident at the Chernobyl nuclear reactor. The funds will be used to secure the so-called sarcophagus, which ensures the safe encapsulation and containment of the ruined reactor. In April 1986 Chernobyl was the site of the world's most serious accident to date in the commercial utilisation of nuclear power.


Today the State Nuclear Regulation Committee of Ukraine issued the license for Chernobyl NPP decommissioning.


Flooding of diesel generator building, unavailability of emergency power supply systems. Reactor has to be shut down.
(source: greenpeace nuclear accident calendar)


A group including BNFL Engineering Ltd., and Ukrainian partners has signed a two-year, multi-million-dollar contract to provide consulting services on the Chernobyl Implementation Project. The project is part of the Chernobyl program funded by the G7 nations, Ukraine and others through the European Bank for Reconstruction & Development. The team will examine the existing Chernobyl-4 sarcophagus and develop a pre-conceptual design to convert the ustable structure, so that the wrecked reactor´s site can be made environmentally safe. Ukrainian members of the joint venture are: the State Scientific-Research Institute of Building Constructions, Kiev Scientific R&D Designing Institute, and the Interdisciplinary Scientific & Technical Center.


The Ukrainian government and the European Bank for Reconstruction & Development (EBRD) agreed on projects that will allow work to begin on improving the sarcophagus over Chernobyl-4.
Under the first agreement, between EBRD and state nuclear utility Energoatom, the bank will allocate ECU 103,5-million to fund the "early biddable projects" in the international Shelter Implementation Plan (SIP). It foresees implementation of projects in four areas over two years: stabilization of structures and definition of strategy for a new cover; perfecting monitoring systems for the sarcophagus; management of dust and water inside the existing shelter; and research into technologies for managing fuel-containing materials within the structure.
Energoatom signed a contract in late April with a consortium of Bechtel, Battelle, and Electricite de France to run the Chernobyl SIP Project Management Unit (PMU). The initial $28-million contract runs for two years, with an option to extend for the full eight-year SIP program.
The contract anticipates that the Ukraine government will guarantee consortium participants indemnity against nuclear liability connected with their services. EBRD has undertaken to develop a cetralized insurance policy for the SIP project, sesigned to cover all kinds of risk and help lower the cost of contracts, according to a representative of the Chernobyl Nuclear Power Plant. Liability coverage, and notably the problem of obtaining insurance coverage at the Chernobyl site, has been one of the major issues blocking conclusion of the SIP contracts. By the end of the year, the bank will have allocated about $130-million of Shelter Fund money.
The second agreement, between the EBRD and the Ukraine Ministry of Environemnt & Nuclear Safety provides $9,5-million to support the ministry´s Nuclear Regulatory Administration (NRA) in licensing SIP activities.
Fourteen organizations "from the U.S., Canada, Germany, France, Switzerland, Slovakia, and Ukraine" expressed interest in bidding on the regulatory support contract, worth on estimated $600.000, in late May or early June.
Ukraine officials have said $750-million is needed for the first phase of the shelter project, but to date only a fraction of that has been pledged.


The Ukrainian Ministry for Energy last week proposed extending operation of Chernobyl-2 and -3 until 2016, the end of their design life.
Minenergo calculates this could bring revenues of 2,39-billion Hryvnia ($1,15-billion). If Chernobyl-1 were restarted and operated as well, the gain would reach Hrv 3,58-billion ($1,76-billion). In contrast, if all the Chernobyl units are shut in 2000, as the government has pledged if replacement power is available, the total loss by 2015 will amount to Hrv 3,6-billion.

None of the four Chernobyl RBMK-1000 units is in operation today, although unit 3 is technically ready for restart after a long repair outage. Chernobyl-1 was closed definitively in late 1996, and Chernobyl-2 has been off-line since a 1991 fire.
Energoatom´s most pressing task today is restart of Chernobyl-3 after a long repair during which more than 330 cracks were eliminated in the reactor cooling piping. Another 100 smaller indications remain without repair.


A two-week unplanned inspection of the Chernobyl-3 nuclear unit has revealed no violations of safety requirements, although "drawbacks" in safety culture were found. That is the verdict given by the Head of Ukraine's Nuclear Regulatory Administration (NRA) on the outcome of the investigation by officials from the Ministry of Environmental Protection and Nuclear Safety. The special probe was launched after a peer review by experts from the World Association of Nuclear Operators (WANO) resulted in a negative picture being painted of the overall safety situation. The head of the NRA, said the Chernobyl nuclear plant faced no problems associated with meeting the nuclear safety requirements of unit 3. Plant personnel were adhering to requirements set out in safety procedures and regulations. He said practically all planned safety improvement measures had been implemented, and the physical characteristics had been improved in line with design modifications made after the 1986 accident in unit 4. The NRA head added that there were no particular problems with fire safety at Chernobyl, although five out of 20 planned fire protection measures had not yet been implemented.
The government inspectors did find a number of violations supporting those highlighted by the WANO specialists. He mentioned in particular:
· instances of workers failing to follow established rules for personal safety;
· shortcomings in maintenance management that could result in higher personnel radiation exposure;
· "formalistic" attitudes among personnel in performing equipment operation duties;
· evidence of careless house-keeping indicated by some dirty and littered areas.


A major project to improve safety at Chernobyl-3 a and build spent-fuel and liquid waste facilities ready for decommissioning of reactors 1, 2 and 3 - is to be run by a team led by Westinghouse.
The US$ 125 million project is being funded by the European Bank for Reconstruction & Development.
Partners with Westinghouse in the US$ 10 million management contract are Britain's NNC Ltd. and the Kiev Design Institute.
The PMU will provide integrated project management and engineering support for 15 near-term improvements on Chernobyl-3:
· in-service inspection equipment for reactor fuel channels;
· in-service inspection equipment for main steam/water circuit;
· steam drum and pipework movement monitoring;
· plant radiation monitoring system;
· personnel radiation monitoring;
· personnel access control system;
· maintenance tools and equipment;
· essential electrical spares.

Technical safety improvements
· neutron flux instrumentation;
· reactor control and absorber rods;
· hydrogen monitoring system;
· spare parts for emergency diesel generator;
· new 6-kV switchgear for essential electrical supplies;
· main steam relief and pilot valves;
· vibration monitoring equipment.


G7 leaders will discuss in July an accord to spend US$ 800 million to stabilize for 50 years the sarcophagus entombing the wrecked Chernobyl-4 reactor.
The 22 related projects will include structural improvements, dust suppression and enhanced radiation protection systems.

Initial operation of Vector, to collect, process, and store low- and medium-level waste, is projected in 1999, for a cost evaluated at US $78-million, including 8 million $ for civil and construction works. (An earlier figure of 150 million gUS$ turned out to be an error.) Further construction is estimated to cost260 million US$ including 35 million for civil and construction works.


The EBRD signed an agreement under which Ukraine will receive a grant worth 118 million ECU (150 million US$) from the EBRD's Nuclear Safety Account (NSA). The grant is to finance decommissioning and safety measures as part of international moves to close Chernobyl by 2000. The grant is part of a total amount of 350 million US$ financed by NSA, TACIS and bilateral donors.
The grant comprises three elements: provision of an interim spent fuel storage facility, a liquid waste treatment facility and short-term safety measures for unit-3.


Neutron radiation levels inside the Sarkophagus increased sharply.Specialists are investigating whether this could cause a chain reaction. The increase was only temporary.
Scientists don't have full control over the fuel masses inside the sarcophagus,


Fires inside of the 30 km zone led to an increase in radiation. This was registered in Southern Belorussian regions.


Work continues on the study being conducted by the Alliance with funding from the EC: stabilization of the existing Chernobyl-4 sarcophagus, design of a new concrete structure for 100-year operation, and estimate of costs. Initial results of the study, awarded in 1994, were presented to Ukrainian authorities a year ago.
EC is negotiating contracts for a peer review of the Alliance technical/economic proposals. In parallel, the EC has asked the Alliance to conduct a value engineering analysis of the proposal as a function of cost and risks, and a sensitivity study to assess the impact on project costs of changing work conditions, particularly using higher worker dose limits foreseen by the International Commission on Radiological Protection for recovery actions as opposed to normal operations.
The working document submitted to Ukrainian authorities estimated the cost of the new sarcophagus at between $ 1.1 - and $1.5-billion, 65% of it devoted to construction. Preparatory work was estimated to cost between $181- and $186-million; shelter construction between $605- and $689-million; shelter equipment between $109- and $122-million; project management between $250- and $280-million; and stabilization of the original sarcophagus between $75- and $150-million.


Investigations by German and Russian researchers have concluded that the massive lid of the defunct Chernobyl-4 reactor, suspended about 30 meters above the mass of dust and corium on the unit's floor, likely will not collapse as feared.
The heavy top of the reactor was blown off its supports when a power excursion on April 26, 1986 caused the Chernobyl-4 core to explode. It has been hanging at a precipitous 75% angle since then, in the aperture opened by the explosion. Until now, experts have feared that the heavy metal top could crash to the floor and unleash a renewed emission of radioactive dust into the environment around the plant.
The official said that the lid could be dislodged from its perch, "but then it would likely slide down to the bottom of the reactor, not crash down," he said, since investigations showed that the lid's fall would be impeded by remaining support structures under the aperture. The official said that an external event - most probably an earthquake - would be necessary to dislodge the lid from its perch. According to GRS data, local quakes have been recorded at just over Richter Scale 5. Events between Richter 6,3 and 7,4 have been recorded in the Carpathian Mountains, 700 kilometers to the west.
There is more concern, said Alexander Borovoi of the Kurchatov Institute, about the effects of precipitation, which is falling onto the top of the sarcophagus at the rate of 10.000 cubic meters per year. About 3.000 cubic meters of water are inside the structure.
Borovoi said that concern is increasing about the water contamination problem since the groundwater level under the reactor has been rising since 1993-94. The threat to the groundwater in the area is more acute because up to 700 kilograms of fuel material are buried in the ground on the plant site, and an additional 3.000 kg are distributed outside the evacuated 30-km zone.


A November 1995 event at the Chernobyl-1 RBMK has been uprated to Level 3 (near-accident) on INES.
The event, which involved contamination of reactor rooms by a damaged fuel element via the fuel loading machine, comes on the heels of claims by Ukrainian nuclear operating committee Goscomatom that 1995 was an exceptionally good year for nuclear plant safety in Ukraine.
The number of INES-reported-incidents at Ukrainian reactors was nearly halved, compared to the previous year, from 140 to 85. But the most spectacular drop had occurred at Chernobyl, from 15 events in 1994 to four in 1995, almost a fourfold decrease. Most of the Ukrainian events were rated at INES Level 0 (below-scale), and only 10 were classified at Level 1 (deviation).
The November event led to a dose to one employee exceeding the statutory limit of 50 milliSievert (5 rem) per year.
The incident occurred November 17 during extraction of a failed fuel element from one of the RBMK´s 1.600-plus fuel channels.
On December 11, in one room investigators found pieces of nuclear fuel, described by NRA as"black crumbs". Near the largest piece, which measured some 5 millimeters in diameter, activity reached about 200 rad per hour.


Restart after completion of repairs including replacement of 39 fuel channels. This replacemnt is considered to be a "dress rehearsal" for major fuel channel reconstruction needed in all 3 Chernobyl units, which could allow operation until 2010-1015.


Restoration because Ukraine threatens to restart unit-2 if the west doesn't provide funds for new NPPs: one of the two turbogenerators has been repaired the other could be replaced with one of unit-5. Most important task is unloading of fuel, which may be reused at unit-1 and upgrading of safety.


Leak from a spent fuel pool at Chernobyl site.


Reactor was reaching operating capacity after maintenance when water level in RCS dropped suddenly. SCRAM


Fire in the wall separating unit-3 and -4 in an "unserviced area of the sarcophagus.smouldering wooden structure was found in a room classed as ventilation centre. fire was extinguished within 30 minutes


Cable fire in auxiliary building caused by a short.


Failure of an electrical generator switch followed by generator seal failure and ejection of oil and hydrogen caused fire and significant damage to the turbine building. Collapse of building's roof and damage of a generator. Reactor was shutdown and RHR system remained operable, due to prompt action of operators.