Greifswald Nuclear Power Plant

F1

Decommissioned Reactors ( gross ):

Set construction ( gross ):

The decommissioned Greifswald nuclear power plant (more precisely, nuclear power plant Lubmin, also: Nuclear power plant North ) was located in the municipal district of the seaside resort Lubmin near Greifswald and was the larger of the two operating nuclear power plants in the GDR. The nuclear power plant was officially called "VE Kombinat nuclear power plants " Bruno Leuschner " Greifswald ". It was shut down in 1990, then finally shut down in 1995 and since then has been in the demolition. Today's owners are the energy Nord, who also run the adjacent Interim Storage North.

• 2.1 embrittlement of the reactor pressure vessel ( blocks 1-4 )
• 2.2 Passive safety reserves

• 6.1 lines
• 6.2 cooling

History

Construction of NPPs (block 1-4 )

Even before completion and commissioning of the first commercial 70 MW experimental reactor Rheinberg the GDR in 1966 was on 14 July 1965 intergovernmental agreement between the GDR and the USSR to build a second nuclear power plant with 2000 MW of electrical power on the territory of the GDR as well as delivery the core components for this from the USSR closed.

As part of a site - selection process, Lubmin prevailed near Greifswald. This was due to the year-round adequate through the Baltic Sea cooling water supply, the low agricultural use value of land and low population density, which should minimize the effects of an incident. In contrast, the large distance of the north of the GDR by the power generation centers in the south and the resulting transmission losses spoke.

1967 saw the development of the site and in 1969 the actual building of four reactor units of type WWER-440/230, the prime contractor was the VEB BMK coal and energy. The construction of the first four blocks was carried out by the usual international time frame, was criticized at the 14th meeting of the Central Committee of the SED from the 9th to the 11th December 1970 that the cost of the project were to twice that of the financial statements. The commercial power operation began in 1974 in Block 1, 1975 in block 2, 1978 in Block 3 and 1979 4 in Block From then covered the first four blocks about 10 % of the electricity needs of the GDR.

Enlargement by four more blocks (block 5-8 )

Mid-70s, the decision to expand the nuclear power plant was hit by another four blocks with a net capacity of 408 MW, which should be operational by 1980. In blocks 5-8, the particular safety aspects significantly improved reactor type was WWER-440/213 used the example has more redundant main cooling lines, a revised emergency cooling system with at least theoretical control large coolant loss and a wet condensation and today is still operated in several Eastern European countries.

The completion of the new blocks was delayed significantly due to a delay in delivery on the part of Soviet heavy industry as well as quality defects to the delivered as well as in the GDR manufactured components. After insistent complaints in Moscow on non-compliance of the supply contracts, the GDR leadership was for the nuclear industry by the Ministry pointed out that this

Block 5 took until much later in 1989 the trial operation, block 6 was completed in 1990, but no longer loaded with fuel assemblies.

Construction of district heating line

In 1982 started the construction of a district heating. In 1983 and 1984, respectively 75 MW of district heat from the blocks 1 and 2 could be coupled and approximately 14,000 homes as well as some industrial plants are supplied.

Carryover of maintenance measures late 80s

The WWER-440/230 reactors of Units 1 to 4 corresponded with their conception of the late 60s under a number of security issues not generally accepted in the 80s standards. In addition to basic conceptual weaknesses in particular the increasing embrittlement of the reactor pressure vessel in Unit 1 to 4 was (see section below ) is very concerned by the State Office for Nuclear Safety and Radiation Protection of the GDR. As part of a large-scale reconstruction of Units 1 to 4, an approximation to the standard international safety standards and a reliable operation for the remaining term of the reactors should reach / be ensured. The project did, however, due to the lack of cooperation of Soviet authorities initially not progressing. Over the 80 years, the state of the system deteriorated so much that the supervisory authority for block 1 called for an immediate reconstruction in May 1987, as the operation is otherwise unacceptable safety:

Against the backdrop of the worsening energy crisis in the GDR Politburo pushed on 30 June 1987 on the reconstruction measures for the Greifswald nuclear power plant. The reactor block 1 was started up again, contrary to the claims of the safety authority. At least the thermal treatment of the reactor pressure vessel to the annealing of the embrittlement of the weld was made, however, one year later.

Within the GDR leadership the future of Units 1 to 4 of the Greifswald nuclear power plant was controversial. While the Central Committee of the SED May 30, 1989 decided the large-scale reconstruction of the reactor units 1 to 4, one was at the State Office for Nuclear Safety and Radiation Protection against Soviet authorities consider that

Also in this issue, the formally independent regulatory authority ultimately had to bow to the party line and endorse the planned reconstruction.

Decommissioning in the years of change

By on February 1, 1990 at the magazine "Der Spiegel" published report " time bomb Greifswald " were first in the public safety deficiencies in the Greifswald nuclear power plant ( "Chernobyl Nord" ) is known. In addition to a collection of hitherto unpublished incidents and referring to the embrittlement of the reactor pressure vessel of the article also claims to uncontrolled corrosion problems in the reactor pressure vessel and a problematic fluid dynamics in the reactor core as a result of over-sized main circulation pumps. The latter two issues have been contradicted in a later published security advisories of the Society for Reactor Safety ( GRS).

The GRS began the nuclear power plant to be reviewed in the course of reunification in early 1990 using Soviet and French experts. In addition to general safety-related faults on all four blocks as the lack of redundancy for emergency cooling of the reactors, the non- mastery of breakage of the main coolant line and the absence of a containment or a wet condensation resulted in particular those resulting from the embrittlement of the reactor pressure vessel serious safety concerns (see section below ) 3 to a temporary closure recommendation in February 1990. This was promptly followed at blocks 2 & by the GDR authorities.

Block 4 has been covered in early summer 1990 for the upcoming revision and no longer put into operation. The East German government decided on 1 June 1990 on the basis of an opinion of the GRS that the blocks 1 to 4 can not be accommodated at a reasonable cost to an eligible for approval by BRD right level and thus should be turned off. To supply the district heating facilities remained connected by block 1 until 17 December 1990 and became operational immediately after commissioning of a temporary oil boiler switched off last. Since 1995, the district heating supply is largely due to gas-powered combined heat and power.

On November 17, 1990 and the trial operation of Unit 5 was prohibited. This WWER-440/213 reactor is indeed bring with additions of security systems on a West German Atomic Energy Act appropriate level of security, but no West German energy company was willing to assume the cost and approval risk for Block 5 ( and 6) .. The retrofitting costs would approximately 50 million marks be for block 5 and 6, and would, according to a former employee after 6 months of operation have been recouped.

Dismantling

In subsequent years, a deconstruction concept was developed in which using a part of the permanent staff of the power plant whose dismantling should be done. On 30 June 1995, the plan has been approved and the nuclear power plant officially shut down. At that time the cost of the demolition of three to five billion euros were estimated. By 2007, 2.5 billion Euros have already been invested. 2012 should be terminated and the dismantling of the state reached a "green field ".

In April 2012 it was reported that the operators in order to save costs, a combination of immediate dismantling and safe enclosure plans: For example, most plants should be immediately demolished the buildings, however, are still remain 50 years old and are degraded only when the radioactive radiation has subsided. Environmentalists criticize that this decommissioning will unnecessarily delayed.

In February 2013 it was announced that the main activities of decommissioning to be completed in 2015.

In the public eye the work fell again, as in 1996 amid protests by Greenpeace 235 unused fuel to the Hungarian Paks nuclear power plant with reactors of the same design have been delivered.

Of the approximately 10,000 people who worked at the power plant operating times are still about 1,000 employed. You are responsible for the energy Nord GmbH for the dismantling and disposal of nuclear plant components. Since the closure of the power plant and a variety of built for the workers of the power plant housing estates were built back in the east of Greifswald.

Safety aspects of plant

The nuclear reactors at Greifswald come from Soviet production and possess some unique features compared to Western PWRs:

Embrittlement of the reactor pressure vessel ( blocks 1-4 )

The VVER -440 reactors of all types, the fuel assemblies are positioned very close to the wall of the reactor pressure vessel. Produced during the nuclear fission neutron place by only a short path through the water back, be a little hard braked accordingly and meet with high energy on the wall of the reactor pressure vessel. As a result of the neutron entry of the steel changes its material properties and tends to fracture with increasing irradiation.

As a critical vulnerability has been doing the weld 0.1.4. (see right figure ) were found in the center of the reactor pressure vessel. Inter alia, from experiments with Einhängeproben from the Loviisa nuclear power plant in Finland is known that the embrittlement of the weld progresses three times as fast as was forecast when configuring the equipment. The cause is too high copper and phosphorus concentration is suspected in the material of the weld. Technically it describes the embrittlement by the ' Sprödbruchübergangstemperatur ' - above this temperature tends a material to elastic deformation, can be present in the material below to cracks suddenly a brittle fracture may occur.

In the case of a current with full load reactor in need with borated water due to a technical defect of an emergency shutdown, the thermal shock can cool the reactor pressure vessel at high pressure continues under the Sprödbruchübergangstemperatur and thus bring him to burst in initiating the Havarieborwassers.

As a preventive countermeasure can be provided with the reactor core Abschirmkassetten to reduce neutron entry into the weld seam. Furthermore, it was recommended by the reactor developers OKB Gidropress in 1984, preheat the Havarieborwasser to reduce the thermal shock in the event of an emergency shutdown. This retrofit has been omitted in the Greifswald nuclear power plant. If the embrittlement of the weld at an advanced stage, the pressure vessel may annealed by heating at about 500 ° C and the initial material properties are largely restored.

Passive safety reserves

The WWER-440/230 rectors of Units 1 to 4 and the advanced second generation WWER-440/213 (blocks 5-8 ) have opposite West German pressurized water reactors such as the convoy in relation to the emergency cooling and the removal of decay heat over much greater passive safety reserves. The primary circuit of a VVER -440 reactor contains, based on the thermal performance of approximately 160 % of the water compared to a convoy reactor and in the secondary circuit three times the amount of water. These large coolant inventories allow in case of total failure of the power supply, the removal of decay heat over a period of about 7 h and thus extend the time frame for responding to incidents significantly. In this respect, the short-term failure of all cooling pumps at a VVER -440 reactor is far less critical than would be the case with a Western-type reactor.

Incident

On December 7, 1975, a electrician wanted to show his apprentice how to bridge electrical circuits. This led to a short-circuit on the low voltage side of the generator transformer of Unit 1 by the arc produced a cable fire broke out. The fire in the main cable channel destroyed the power supply and the control lines of five of the six main coolant pumps. The sixth was accidentally connected to the power circuit of the neighboring reactor and secured a makeshift cooling of the reactor core. The fire was brought by the company fire quickly under control and the power to the pumps are provisionally restored, since immediately after the occurrence of the fire counter-measures have been taken and the operating team at any time of the accident made ​​the right decisions. After this near - disaster measures to improve fire protection have been proposed within the power plant and introduced the " spatial separation " in safety-related equipment, which took several weeks to complete; while each main coolant pump got its separate power supply. The fire protection measures were implemented only eleven years after the incident of 1975 and in the meantime there was at least one other fire ( 1977 in a water treatment plant ). The incident in 1975 was only after 1989 in television and the mirror (eg Output 1 February 1990) made ​​public. Through Soviet sites was already informed the IAEA a few hours after the incident that regarded this accident first in INES 4, later in INES 3 ( precursor to an accident, here a " station blackout " - melting scenario) corrected. The 10-percent limit of allowable activity release was not exceeded. Subsequent evaluations of the operations by a government commission and the confirmation of the conclusions drawn by the Commission by the IAEA to show that an experienced operating team can compensate for plant-specific vulnerabilities. This incident is therefore incorporated as a standard accident scenario for VVER -440 in the simulator training in Greifswald to 1990.

Information Centre

On the grounds of the nuclear power plant is an information center that provides information, inter alia, about the history of nuclear energy, the VVER used in Greifswald, decommissioning, dismantling and disposal. It is by appointment also has the unique opportunity to travel the "visitor route - the primary circuit " to visit the completed, but never loaded with fuel reactor block 6. Radiation protection measures are not necessary for this reason. In the exhibition center and on the open spaces original components are issued.

Turbine Hall

All turbines and generators of the power plant were housed in a 1,000 -meter-long hall, which was one of the longest industrial buildings in Germany.

This spatial proximity and linkage was partially offset only by the fire safety measures after the incident in 1975. But it was still: The reactor units were, as a report from Greifswald noted " in mutual quasi- local as well as circuitry linked Störnähe ". Thus would be by a fault in one of the reactors at the same time, a second was involved.

Technology

Lines

Two double-circuit 380 kV lines led to the substation and the substation Wolmirstedt Ahrensfelde in Berlin. The former was with 287.8 kilometers, the longest power line in Germany.

Cooling

The former nuclear power plant Greifswald / Lubmin moved into its cooling water through an open inlet channel from the Spandowerhagener Wiek, which in turn is fed by the river Peene. After flow cooling of the reactor units per hour were approximately 20,000 ... 40,000 m³ ( 1 m³ = 1 t) cooling water with high heat load over an open outlet channel in the Bay of Greifswald passed. This could be dispensed with cooling towers. A small part of the heat also went into the district heating network of Greifswald.

Efficiency

The efficiency was as in nuclear power plants of this type common in about 34 % in terms of pure power generation. However, since heat, was used as district heating for the city and process heat for industry, combined heat and power generation process, the utilization rate was based on the utilization of the stored energy in the fuel, uranium above this value.

It existed immediately prior to the change in the GDR nor concrete plans for the expansion of the district heating network by cities and towns as Wolgast, the Riems, Wusterhusen and Stralsund.

Data of the reactor units

The Greifswald nuclear power plant had a total of eight blocks: