Kozloduy (Bulgaria)

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200 kilometers north of Sofia Bulgaria's first nuclear power station is located - in total six PWR units were constructed at the site:

4 units WWER 440 V230: grid connection from 1974 to 1982
2 units WWER 1000 : grid connection 1987 and 1991

The two oldest VVER 440 units have been closed in 2002. At the end of 2006 units 3 and 4 were also shutdown.
For units 5 and 6, lifetime extension is planned.
For a new unit (Kozloduy 7) an environmental impact assessment was started in 2013.

Operator of the NPP-units: KOZNPP
Supplier: AEE

Facilities in Kozloduy

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The Bulgarian parliament announced that Bulgaria plans to recommission the two reactors in Kozloduy (3 and 4), which have been shutdown in 2007. They argument that the Russian gas crisis made this step necessary (although the gas supply had already restarted at that moment). The shutdown of the reactors has been a condition in Bulgaria's EU association agreement. Austria protests against the recommissioning.

Incident in Kosloduj

In the Bulgarian nuclear powerplant Kosloduj one of the reactors was shut down after a short-circuit during the night of friday to saturday, the direction of the powerplant announced. The incident was located at the connection between the reactor turbine and the generator. No radiation was released.


During the removal of nuclear waste several containers of low-level nuclear waste fell over. No increased levels of radioactivity were detected.


Russia will continue storing used nuclear fuel from Kozloduy even after 2020, until the exploitation period expires executive director Vassily Konstantinov from TVEL stated.


After the breakdown of a pump a high number of elements of the emergency shutdown failed. In addition deficiencies in procedure and a delay in the discovery of the source of the incident occured.


In 2004 74 events were reported to the Nuclear Regulatory Agency NRA. One of these was rated INES level 1, 56 events were rated INES level 0, while the rest of the events proved to be out of INES.


In 2004 more than BGN 17 million were invested in the modernization programmes for Kozloduy 3 and 4, and at each Kozloduy unit more than 35 technical improvements were implemented.


By the end of 2004, more than 73% of the total scope of Units 5 and 6 Modernization Programme had been completed. The total number of measures implemented rose from 98 at the end of 2003 to 155 at the end of 2004. Since the beginning of the Programme, investments in the modernization of equipment have reached EUR 385 million.


Bulgaria will receive EUR 7.9 M for boosting the safety of Kozloduy under the EU PHARE programme. The memorandum might be signed officially by the end of the year. The projects plan the improvement of Kozloduy N-plant security, the construction of a radioactive wastes processing plant and depot at Novi Khan.


Russia's TVEL contract with Bulgaria for storing spent fuel from Kozloduy will expire in 2007.


Bulgaria will be financed with EUR 61.9 M for the decommissioning of its two oldest units.
In the course of accession talks, Bulgaria has agreed on the closure of another two units on the grounds of EU concerns over the safety of Soviet-designed 440-MW pressurized water reactors. The EU claimed they lack a concrete safety encasement that would prevent radioactive stuff from spreading in case of an accident. Decommissioning units 3 and 4 was set as a precondition for the country's accession to the EU in 2007, as scheduled.
The nuclear lobby and Bulgarian opposition parties, including the head of state Georgi Parvanov, protested that the reactors are economically necessary and called EU demands "arm-twisting."


A contract was signed with a consortium of German companies for the design and construction of a facility for the dry storage of spent nuclear fuel using casks. Kozloduy International Decommissioning Support Fund finances the project, which will provide conditions for safe storage of WWER-440 assemblies for over 50 years.


A contract for the design and construction of a new storage for spent fuel at Kozloduy was signed with a tie-in between Germany's RWE NUKEM Gmbh and GNB mbh. The contract is worth EUR 48.7 M and is financed by an international fund administered by the European Bank for Reconstruction and Development. The new facility will be able to store casks of spent nuclear fuel up to fifty years. The design of the storage will allow expansion of its capacity. The storage will be constructed for four years and a half.


The results of the peer review conducted of the the Kozloduy N-Plant in mid-November by an expert mission of the European Union's Atomic Questions Group/Working Party on Nuclear Safety (AQG/WPNS) are expected to be officially announced in February 2004.


Unit 6 of the Kozloduy Nuclear Power Plant was brought back on stream on December 5th. The reactor was stopped on September 2 for repair, refuelling and upgrading.
During the repairs 30 per cent of the improvements stipulated in a programme for upgrading Units 5 and 6 were completed. The upgrading for this two 1,000 MW units shall be completed in 2006.


A EU peer review of the safety of Units 3 and 4 of the Kozloduy plant will be purely technical and will look into the implementation of prescriptions by two previous missions of the EU's Atomic Questions Group, the Energy Ministry said.
The programme notes that the expert mission is not competent to discuss political matters, and also that it is not expected to repeat the detailed assessment of measures implemented under all safety upgrade programmes.
Twelve experts are expected at Kozloduy for the peer review.


Thirty-four per cent from the planned technical improvements for the 1000 MW power units 6 of the Kozloduy nuclear power plant will be completed in September to December. The improvements are part of a programme for the modernization of the generating unit which will increase its nuclear and operational safety.
The 1000 MW power unit 5 too will be modernized in March 2004. The goal is to achieve a maximum percentage of use of the nuclear facilities, 80-85%, in 2007. The percentage now is 72%.
The modernization of the two units will absorb 152 million euros. A total of 212 technical improvements will be made. It is expected that the achieved safety level after the improvements will allow to extend the operational potential of the units 15 to 20 years longer than their designed life, Kostadinov said.


A television monitoring system will be built at the Kozloduy Nuclear Power Plant to monitor the plant's physical protection. This measure was recommended from by experts who reviewed the physical protection of the nuclear materials and installations at Kozloduy in February 2002. At their request, the US Department of Energy has agreed to finance the project. The first stage is to be completed by March 2004.


On October 10, 2003 at Kozloduy NPP site, the Nuclear Regulatory Agency officially submitted to the plant management an operational license for Units 5 and 6 for six years in compliance with the requirements of the new Safe Use of Nuclear Energy Act.


European Union expert mission will assess the safety of two controversial reactors at Bulgaria's only nuclear power plant in the second half of November, an official said Thursday. Bulgaria has asked for the review in hopes to extend the 2006 deadline it has agreed with the EU to permanently close units 3 and 4 of the Kozlodui plant.
The EU says that the 440-megawatt pressurized water units 3 and 4 are dangerous because they lack safety containment. Bulgaria contends it has upgraded the Soviet-designed reactors well enough to use them until the end of their lifespans, expiring in 2010 and 2012 respectively. A recent inspection by the Vienna-based International Atomic Energy Agency has concluded that the reactors in question are safe.


Russia will no longer store nuclear waste for Bulgaria´s Kozloduy nuclear power station.
Russia would continue to help Bulgaria process nuclear waste, but the processed waste must be sent back to Bulgaria for storage. According to a newly-released decree, it is illegal to store nuclear waste for other countries in Russian territory, the Russian ministry said. Russian environmentalists in the Ural´s city of Chelyabinsk have protested for several times against underground storage for nuclear waste in the city, reports said.


The 1,000 MW Unit 6 of the Kozloduy Nuclear Power Plant was shut down at 11 a.m. local time on Tuesday for elimination of a technical defect, said Yordan Georgiev, Atomic Energy and Nuclear Safety Director at the Ministry of Energy and Energy Resources.


A court annulled Friday a government decision to shut down early units 3 and 4 at Kozloduy on whose closures the European Union is conditioning the admission of the Balkan country. The Supreme Administrative Court said the Cabinet had illegally agreed to permanently close the two units in 2006. The court ruled that the government infringed legislation prohibiting any reactor closures before Bulgaria joins the EU.
In January another panel of the Supreme Administrative Court annulled the decision about the closures but the Cabinet appealed. On Friday an extended panel of the same court confirmed the previous ruling.


Experts of the World Association of Nuclear Operators (WANO) said after a two week mission to study the safety of Kozloduy Units 3 and 4 that the facility fully matched international safety standards. The inspectors said that the plant had fulfilled all recommendations that similar previous missions made. Three of the improvements in the plant would be internationally recommended as good practices in the branch.
An earlier inspection by the Vienna-based International Atomic Energy Agency has included that units 3 and 4 are safe.


Last year Bulgaria closed Kozloduy's two oldest units and later agreed to close two more by 2006. All of the four units are 440-megawatt pressurized-water without safety containment, installed between 1974 and 1982.

The EU insists those reactors are a safety risk and Bulgaria ought to close them if it is serious about joining the Union.

Yordan Georgiev, deputy director of the Kozloduy power plant, said the plant would decrease its output but its expenses would remain the same due to conservation works costs at the decommissioned units. The production cost of electricity from Bulgaria's only nuclear plant will rise by 50% if the country bows to European Union pressure to close the two reactors,

The plant has two newer 1,000-megawatt reactors with safety containment that are - in view of the European Union - no safety issue.


Unit 3 received an 8-year operational license. The license was issued by the Nuclear Regulatory Agency of Bulgaria based on the new Safe Use of Nuclear Energy Act.


The Nuclear Regulation Agency of Bulgaria issued ten-year operating licence for Unit 4 of Kozloduy based on the new Safe Use of Nuclear Energy Act.
The new license does not significantly improve the chances of Bulgaria in the negotiations that it holds with the European Union on the exploitation terms of Kozloduy's units 3 and 4. Most members of the European Union regard Bulgaria's Russian-type nuclear units 3 and 4 as potentially dangerous and want them shut down by 2006. The government in Sofia agreed to this deadline provided the EC dispatches a peer review. Bulgaria now hopes to re-negotiate the closure timetable if the results of the check prove favourable. The country hopes for EU membership in 2007.


A Kozloduy peer review won't happen in the first half of 2003, according to Greece sources.
Kozloduy management and the Bulgarian government have said they hoped for an EU-commissioned peer review of Kozloduy-3 and -4 before mid-2003. The Bulgarians agreed last year to shut the two units, which the EU has branded as non-upgradable at reasonable cost, by 2006 but insisted on the peer review which they expect to confirm the VVER-440 units have in fact been upgraded and are safe. Plant management announced that a World Association of Nuclear Operators peer review visit to the units will take place June.


The production cost of electricity generated by the Kozloduy nuclear power plant will rise by 10 per cent at the most by 2006, said K. Shoushoulov, Chairman of the State Commission on Energy Regulation. He talked to journalists at Saturday' public debate on the energy sector bill.

The production cost of electricity will rise due to the modernization of Units 5 and 6, not because of the possible decommissioning of Units 3 and 4, according to Shoushoulov.
Without mentioning figures, he said Kozloduy's production cost is lower in 2003 than in 2002.
The commission's chief expects that in April, after the business plans of the energy companies are analysed, calculations will show if the price of electricity should be raised by 15 per cent in July as planned. Losses in electricity transmission and voltage transformation amount to 22-24 %

This percentage, which includes abstraction of electricity, is unacceptably high. Losses from high voltage transmission amount to 4-5 %. Shoushoulov said the admissible losses posted by the energy companies would be capped.


Nuclear Power plant Kozloduy reported 55 incidents in 2002. The danger they pose is set at about zero, the remainder below that level. No incident reached the first degree on the seven-point scale, Vapirev underlined.

The first of the two oldest units at Kozloduy nuclear power station, 200 kilometres north of Sofia, were decoupled from Bulgaria's energy grid on December 31 and December 30. At the moment, Unit 1 of Kozloduy N-plant is in its 23rd nuclear fuel cycle, and Unit 2 in its 24th fuel cycle. A nuclear fuel cycle corresponds approximately to one calendar year. The designed life of the reactors is 30 years.
The closure of the two oldest units comes after many years of concern over their safety, strong pressure from the European Union, protests from the nuclear lobby and opposition parties that the reactors are economically necessary.


According to the signed Agreement of November 29, 1999 between the Government of the Republic of Bulgaria and the European Commission on behalf of the European Union, Units 1 and 2 were shut down on December 31, 2002. The accumulation of the National Decommissioning Fund continues. A disbursement plan is developed for the purposes of the decommissioning preparation activities during 2003.


The Nuclear Regulatory Agency (NRA) intends to invite the regulatory bodies of Germany, the UK and France to inspect generating units 3 and 4 of the Kozlodoui N PP in October.
The three regulatory bodies will prepare the mission of the
atomic affairs group next year to establish the real state of
the two generating units. The NRA is in the process of signing a contract on cooperation with them.

The Energy Minister said that in the first five years after
the closure of generating units one and two expenditures will
total 35 million euro. Some 300 million leva have been raised
for the closure of the two units plus 100 million euro in
financial aid.

A tender is underway for choosing a consultant to manage the project for the closure of the two oldest units. Three offers have already been received.


"Several days ago we got indications for a minor leak, just on the threashold of sensitivity of the meters," said the N-plant press office. Kozloduy did not have to switch off the reactor because it was within all limits. But as the autumn/winter season approaches, and the power grid works below its peak capacity, the N-plant and the National Electric Company decided to stop the unit for repairs and mend the fault. The radiation situation in the plant and the surrounding area remains unchanged.


Unit 2 of the Kozloduy Nuclear Power Plant was stopped from running due to accidental actuation of a protective mechanism, which brought one the unit's generators off stream.
The emergence of differences between the parameters of Circuits 1 and 2 actuated the protection of Unit 2.
The causes were later identified and preparations began to restart the unit. The radiation situation at Kozloduy remained unchanged, the information center said.


Greasy heat insulation of a heated piping was found smoldering in an engine room of unit 2.
Back then, the plant's information center said that the event does not qualify as a fire and is unrelated to the safety and security systems of the generating unit.


At a news briefing in Parliament, EU Enlagement Commissioner Verheugen was asked about the possibility for the European Commission to review its position on the closure of units 3 and 4. He said the Commission cannot be expected to modify its position on the Energy chapter in the membership talks unless a new joint decision is made, supported by all 15 member states.
According to a Memorandum of Understanding between the Commission and the Bulgarian Government, under which the Bulgarian authorities committed themselves to definitively close down Kozloduy Units 1 and 2 before the year 2003 and to decide on the definitive closure dates for Units 3 and 4 before the presently envisaged closure dates of 2008 and 2010, respectively. The European Commission's understanding is that the definitive closure of those units will take place in 2006 at the latest, according to the Memorandum.


A State Acceptance Commission started work at the Kozloduy Nuclear Power Plant on checking a new Accident Localization System for Unit 3, centred around a jet vortex condenser. The Accident Localization System (ALS), of which the jet vortex condenser is the principal component, offsets the lack of a containment vessel of the generating units using VVER-440 Model V 230 reactors and makes substantial progress in ensuring safety up to modern standards. Such a system was installed on Kozloduy Unit 4 at the end of last year.


Bulgaria and the EU have agreed that Unit 1&2 will be decommissioned before 2003 and the permanent closure of reactors three and four should take place in 2006 at the latest. Kozloduy officials said they had launched preparations to close its two oldest reactors by end-2002 and were modernising the other two older reactors to convince the EU that they could be closed later than 2006. A programme for upgrading Units Three and Four is planned by the end of 2002 to solve 62 technical problems, this should be a strong argument in favour of extending their service life to 2008 and 2010. The major part of the improvements concern the safety program for third reactor.

The Kozloduy officials argue that Bulgarian energy exports are an important stabilising regional factor, because Bulgaria now covers 50 percent of the power deficit in the region. Bulgaria`s main power buyers are Turkey, Greece, Serbia, Kosovo, Albania, Macedonia and the Yugoslav Republic of Montenegro.


One of the two turbines of power unit two was switched off after an oil leak in one of the bearings. The faulty part is in the conventional section of the generator and has no bearing on the nuclear and radioactive safety of the reactor.

After a 72-hour stop for repair works the generator was switched back on.


Although an IAEA review found units 3 and 4 can operate for at least 35 ? 40 years, because all problems that were identified in 1991 have been solved, the European commission is insisting the units be closed no later than 2006.

The EU yesterday approved a loan of Euros 212.5 million. The loan would finance over 40% of a five-year modernisation programme. The money was promised after Bulgaria agreed to close the four VVER 440 plants at Kozloduy. Environmentalists have criticised the loan, because it is a "continuation of an inconsistent strategy" which has "failed to assure the closure of any nuclear power plant in the region." By not insisting on a closure date for the second two reactors the EU was "effectively prolonging the lifetime of high-risk reactors in order to finance Bulgaria's electricity export programme," said Patricia Lorenz of Friends of the Earth/Austria. Follow up: Friends of the Earth Europe (http://www.foeeurope.org),

The EU has repeatedly stressed that the closure of the four Kozloduy reactors by 2002 would be a condition of Bulgaria's eventual entry into the bloc. But the Bulgarian government recently passed a law which would have seen the last reactor decommissioned only in 2010.
Following a meeting yesterday with EU enlargement commissioner, Günther Verheugen, Bulgarian prime minister Ivan Kostov said he was "fully committed" to closing units 1-4 of the Kozloduy plant "at the earliest possible date."

Two units will be closed by 2003, he said, and a review in the same year would decide on closure of the second two. The Commission said its understanding was that they would be closed in 2006 at the latest. Mr Verheugen said the decision would "help open the door" for accession talks to
begin following the EU summit in Helsinki later this month.

In return for the reactor closure, Bulgaria will receive euros 200 million to compensate for loss of electricity from Kozloduy, which generates half the country's supply. Half of this would be transferred only after the last reactor had been closed, a spokesman said.


A steam generator blowdown pipe ruptured during a chemical decontamination job at Bulgaria's Kozloduy-1, polluting the emergency boron tank with chemical products. The reason for the rupture was still not clear as of late last week, and the committee has ordered the plant operator to inspect all similar pipes on steam generators at the Kozloduy nuclear plant.
The event was Level 2 after investigation showed deficiencies in safety culture and violation of procedures without justification.


The integrity of the vessel was discussed at a workshop in Sofia, attended by specialists from the IAEA, the EU, Bulgaria, Germany, Russia, the UK, the US, and other countries. It was established that there was close conformity in the results of independent analysis carried out by Westinghouse, Siemens and Russia's OKB Gidropress. The results indicate that the vessel will be good for the next 6-7 years of plant operation. In January, a period of two years was given by the French and German nuclear safety agencies, IPSN and GRS.


Framatome Siemens upgrade unit5/6

Together with Russian organizations, Framatome-Siemens has won a US $200 million contract to modernize Kozloduy-5 and -6 . Details of the work program and financing are being released as we go to press.


Bulgarian Energy Minister Georgi Stoilov has said that "he is now aware" that the equipment of Kozloduy NPP is reliable.
According to Stoilov, who visited Kozloduy between 10th and 14th March, the safety levels have been raised and an assessment of probable risks will be carried out by the end of March.
In his statement as energy minister at the end of February, Stoilov said that, despite improvements in recent years, Kozloduy posed a high risk.


Bulgaria started talks with Russia about a complex upgrading program for unit-1 to 4. Bulgaria hopes to get a credit from Russia which it will pay back by exporting goods. Costs for the program are estimated at 400 million US$ of which 100 million $ would go for construction of a spent fuel storage.
Reconstruction had been concentrated on the two oldest units, which were restarted in 1992 and 1993 respectively. Kozloduy plans to finish the last stage of reconstruction in 1997.


Shutdown because of a SG air relief leak without release of radiactive substances.


Russia's Kurtchatov Institute is to start soon tests on samples taken from RPV. First results will be ready in November.
Main Contractor for the tests is Siemens with the Kurchatov and two Bulgarian Institutes as sub-contactors.
Technical difficulties delayed the sampling: the critical weld at unit-1' RPV does not have the 2 mm crown which was found at unit-2.


Samples will be taken from the Kozloduy-1 pressure vessel next spring for analysis of ist ductile strength, under an agreement concluded late last month during a visit to Sofia by Viktor Sidorenko, vice minister of Russia's Ministry of Atomic Energy (Minatom).
Kozloduy-1's vessel is the most worrisome of those fabricated in the former Soviet Union for VVER-440 Model 230 reactors because, according to Russian and western experts, it combines a high phosphorus content in the beltline weld (No.4) with high neutron fluence. However, based on the analysis conducted last summer, Russia's Gidropress VVER design institute concluded that Kozloduy-1 could be operated for an 18th cycle within safe margins.
An EDF expert said that the so-called scrapings taken from the No. 4 weld for previous chemical analysis were so deep that they had already affected the smoothness of the vessel surface, so the boat-shaped samples would not likely reduce the vessel's lifetime by much. Western officials also noted that Kozloduy management had earlier allowed sampling at unit 2.
The data for the elemental composition of the No. 4 weld and the vessel base material "practically corresponds" to data from unit 1 in Greifswald, one of the German VVER-440s shut down several years ago. The Kozloduy vessel was produced just after the Greifswald-1 vessel, the Bulgarians note, concluding that "studies of the Greifswald reactor can be used for assessment of the status of unit 1 at Kozloduy."
Russia's Kurchatov Institute has recently worked out a new theory for assessing the behavior of vessel material after annealing, based on experimental results. Instead of the so-called "conservative assumption" which supposes that vessel embrittlement accelerates after annealing, the Russian scientists have found evidence to support the theory of "lateral shift," which postulates that embrittlement resumes at the original pace after annealing, but from a lower starting temperature. A Russian expert said that Kozloduy could likely demonstrate that the unit 1 vessel is in better shape than is assumed today, but only on the basis of analysis of actual samples.


Restart, despite objections from western safety organizations.(GRS, IPSN, Riskaudit); Riskaudit director said that given the impossibility of guaranteeing the resistance of the vessel to PTS, the probability of a catastrophic accident is identical to that of the most likely initiator, a main steam line break, or 1:10.000.
The EC already approved funding for the sampling and contracts were signed with Westinghouse for the sampling and with Siemens for the analysis, but they were not carried out because of the plants resistance. The plant had cited 3 reasons not to take the samples: lack of margins in the vessel wall, the potential loss of safety margins by removing vessel wall material and the risk that tools or other objects could be left in the RPV. The Bulgarians also rejected an offer to provide emergency coal supply.
Bulgaria suggested that the vessel episode was designed to put pressure on Bulgaria to fulfill its commitment, made in exchange for a 1993 nuclear safety improvement grant from the EBRD, to prepare for closure of the first 4 Kozloduy units in a few years.


A consortium of Western safety experts gives its advice on the Bulgarian proposal for restart of the unit which hs been down since March 95. The unit is the most susceptible VVER 440 V230 to RPV embritlement and the assozciated risk of PTS. A 1989 analysis by Rusian and Bulgarian engineering institutes indicated that because of the high phosphorus content of the RPV velds, and despite annealing of the critical mid-core circumferential weld the RPV had already exceeded the transition temperature at which PTS becomes a safety risk. After 4 years of study the IAEA identified RPV status as the most worrisome issue for VVER 440/V2130 safety. One xpert of this IAEA team said the agency feels that unit-1 ought to be shut immediately, unit-3 within 3 years and unit-2 within 5 years. The IAEA did not publish these results but waited for further analysis.
No samples had ever been taken from the RPV material; the concern is still based on chemical analysis with broad uncertainties.
Western companies want to postpone the restart of unit-1, but Bulgaria has loaded the fuel and closed the vesselectrical Kozloduy management is reluctant to take samples from the RPV, because this would reduce the lifetime of unit-1' s vesselectrical Western expert suspect that the paper calculations underestimate the PTS risk.


Bulgaria's regulators are evaluating an upgrade plan for units 5 & 6 which aims at improving both reliability and safety. It includes modernization of I&C and replacement of some original equipment which is causing errors, including spurious signals causing scrams. Design of unit 5 &6 is of 1978 and equipment faults are causing > 60% of the incidents.

The modernization plan was developed by Energoprojekt, Risk Engineering and EDF. The plan is to be submitted to the EBRD for financing. The proposed work will probably cost 150-250 million US$.


Fire in storage facility for LLW.


Leak in MCP (radioactive steam escaped)


Fire in transformer housing room affecting circuit breaker in the reserve power supply.


Failure of generator breaker during startup tests -> short circuit caused fire and loss of. power -> generator damaged.


Leak in MCP triggered plant radioactivity detectors.


Failure of HP injection pump.


Leak in the main flange of a primary coolant pump led to release of radioactivity into the pump room.


Fire in turbine hall which is common for all 4 units. Fire is a recurrent event at the plant. In the period 1987-1990 24 fires occured: 14 in the turbine hall and 3 in the electrical component distribution devices.


SG leakages -> during SG cooldown personnel error led to depressurization of RCS (it was second time at unit-2).