Gundremmingen Nuclear Power Plant

Gundremmingen Nuclear Power Plant
Gundremmingen Nuclear Power Plant: Unit A (left foreground), Units B and C (right) and their cooling towers (rear)
Location of Gundremmingen Nuclear Power Plant in Germany
Country	Germany
Location	Gundremmingen, district of Günzburg, Bavaria
Coordinates	48°30′53″N 10°24′8″E / 48.51472°N 10.40222°E / 48.51472; 10.40222Coordinates: 48°30′53″N 10°24′8″E / 48.51472°N 10.40222°E / 48.51472; 10.40222
Construction began	1962
Commission date	April 12, 1967
Owner(s)	75% RWE 25% E.ON
Operator(s)	Kernkraftwerk Gundremmingen GmbH
Nuclear power station
Cooling source	Danube River
Cooling towers	2
Power generation
Units operational	2 x 1,344 MW
Units decommissioned	1 x 250 MW
Average generation	20,629 GWh
Website kkw-gundremmingen.de

The Gundremmingen Nuclear Power Plant is the highest-output nuclear power station in Germany, producing 2 × 1344 megawatts. It is located in Gundremmingen, district of Günzburg, Bavaria and is operated by Kernkraftwerk Gundremmingen GmbH, a joint operation of RWE Power AG, based in Essen (75%) and E.ON Kernkraft GmbH, based in Hannover (25%). Two units, B and C, are currently in operation. Unit A was the site of the first fatal accident in a nuclear power plant and subsequently of a major accident resulting in a total loss, the only such catastrophe to date in a nuclear power plant in Germany.

Reactor Units

Unit A

Scale model of the Gundremmingen plant, in the information center

The damaged Unit A

Retired turbine from Unit A in front of plant information center

Unit A was a boiling water reactor with an output of 237 megawatts, the first large nuclear power plant in Germany. It was in operation from 1966 until 1977, and during its life generated a total of 13,800 GWh of energy.

Following objections by the city of Nuremberg to the original planned location on the Danube at Bertoldsheim (between Donauwörth und Neuburg an der Donau), because of protected areas for the city's drinking water supply in the Lech estuary, the plant was instead located approximately 50 km up-river in Gundremmingen, between Dillingen und Günzburg. The plant was proposed on July 13, 1962, quickly approved, on December 14, 1962, and placed in service in December 1966. A protest group, the Notgemeinschaft Atom-Kraftwerk Gundremmingen-Offingen (Gundremmingen-Offingen Atomic Power Plant Emergency Organization) was silenced using monies specifically set aside for the purpose.^[1]

In 1975 an incident occurred in which two workers were killed by escaping steam: it was the first fatal accident in a nuclear power plant in Germany.^[2][3][4]

On January 13, 1977 a serious accident occurred that resulted in the total loss of Unit A. In cold, damp weather, two high-voltage lines carrying electricity from the plant short-circuited. The ensuing rapid shutdown of the reactor led to operational errors. Within ten minutes, there was approximately 3 meters of standing water in the reactor building and the temperature had risen to nearly 80 degrees Celsius. Through error, too much water was introduced into the reactor for emergency cooling. Pressure relief valves released between 200 and 400 cubic meters (sources vary) of radioactive coolant water into the building. The water, and also the gases, were later released from the building into the environment.

This was Germany's first and so far only catastrophic loss of a nuclear power plant. Political and regulatory bodies required that in addition to repairs, the unit's control and safety systems be modernized. Because modernization would have required an investment of 180 million DM, and since Units B and C were already under construction, the operating authorities later decided not to return Unit A to service. The contaminated steel parts were contained in protective castings and removed to the interim radioactive storage location in Mitterteich.

In 1983 the decision was made to dismantle the unit.^[5] Dismantling was "far advanced" in 2005^[6] and has led to valuable experience and the development of state of the art processes for the breakdown, handling, and cleansing of radiation-contaminated materials.^[5] According to the operators, approximately 10,000 tonnes of scrap have been created in the process, of which 86% have been re-usable and 14% are to be disposed of in permanent storage as radioactive waste.^[7]

In January 2006 the Bayerische Staatsministerium für Umwelt, Gesundheit und Verbraucherschutz (Bavarian State Ministry for Environment, Health, and Consumer Safety) gave permission for the construction of a "technology center" within the confines of the former Unit A - with the exception of the reactor building. Following conversion and modernization, the following work will be possible there:

• Treatment of remaining radioactive material with the objective of re-use
• Mitigation of radioactive wastes
• Servicing of components
• Manufacture and storage until use of tools and equipment
• Storage and preparation for transportation of treated and untreated wastes pending their conversion or removal from the site.^[5][8]

The statement of permission also allows venting of radioactive materials via the exhaust stacks. Maximum permitted annual radioactive emissions are: 50 MBq for aerosol radionuclides with half-lives greater than 8 days (excluding iodine-131), 0.5 Mbq for iodine-131, and 100,000 MBq for tritium.^[8]

Units B and C

Units B and C are neighboring units of identical construction. Each consists of a reactor building, a machine shed, and a 160 m tall cooling tower. The two units share a 170 m tall exhaust stack.^[9] Construction commenced on Units B and C on July 19, 1976. Unit B was completed on March 9, 1984, Unit C on October 26, 1984. Both reactors are designated Series 72 (for 1972, the year in which they were initially conceived).

Each reactor is loaded with around 136 tonnes of fuel; the reaction elements last approximately five years. Annually, roughly a fifth of them are switched out. Water is drawn from the river via a canal 1.4 km in length and condenses in the cooling towers at a rate of 0.7 cubic meters per second. It is returned to the river through an underground pipe.

Units B and C are, like unit A, boiling water reactors. In this type of reactor, the water flows around the fuel elements, boils, and the steam directly drives the turbines. Thus, in boiling water reactors, in contrast to pressurized water reactors, there is only a single, primary coolant loop. Each unit is loaded with 784 fuel elements. One fuel element contains approximately 174 kg uranium and consists of 100 (i.e. 10 x 10) fuel rods. Units B and C together generate a total of approximately 21,000,000,000 kWh of electricity annually. Hence they are calculated to supply approximately 30% of Bavaria's electricity.^[10]

Net electrical output is 1,300 megawatts per reactor. An increase in the output of Units B and C, from a gross electrical output of 1,344 megawatts each to 1,450 megawatts, was requested in September 1999 but has been suspended for years. On December 19, 2007, the Bayerisches Umweltministerium (Bavarian Ministry of the Environment) mandated an increase in performance of 160 thermal megawatts and in electricity generation of 52 megawatts. In addition, in recent years there has been a plan to convert both units to load management operation, in which the electrical output ("load") is managed. On weekends, at least, these reactors are often throttled back.

At the end of 1994, the operators announced agreements with the nuclear reprocessing plants at La Hague, France and Sellafield, England, and with that opted for long-term interim storage.

In 1995, plutonium-containing mixed oxide fuel elements (MOX fuel) were for the first time used on a large scale in boiling water reactors. Their increased radiation has been repeatedly criticized by environmental protection groups, which have registered around 40,000 protests. Utilization of these fuel elements enables more effective use of available uranium through reprocessing. The operators must guarantee that the reactor can be safely shut down under all operating conditions. And at least once every operating period and upon every alteration to the fuel load in the core, a report on the so-called shut-down reactivity must be submitted, as required by German safety rule KTA 3104.^[11]

Measured emitted radioactivity in 2004 was 3 TBq airborne and 5 TBq waterborne.^[12]

The planned shutdown of the Gundremmingen B reactor has been scheduled for december 2017, and of Gundremmingen C for 2021.^[13]

Interim storage of spent nuclear fuel

Interim storage for spent nuclear fuel (white building in foreground)

Since August 2004, an interim storage facility has been established on the grounds of the nuclear power plant for spent fuel elements with a heavy metal weight of 2,250 tonnes. It contains 192 storage spaces and was placed in operation in 2006.^[14] € 30 million have been budgeted for this. Construction of the building (104 m long, 38 m wide, and 18 m tall) was completed at the end of 2005. After interior fitting with electrical, heating, and ventilation equipment, installation of heavyweight hoists, and remaining exterior work, on August 25, 2006 the interim storage facility was opened and the first containers from the power plant moved in.

To minimize risk of radiation, the facility has two doors each weighing 50 tonnes and thick concrete walls, although at 85 cm they are thinner than in comparable storage facilities in North Germany (e.g. at Brokdorf 120 cm). At 55 cm, the concrete roof is likewise considerably weaker than the roofs of the interim storage facilities built in North Germany (e.g. Brokdorf 130 cm).

The power station operators had submitted a request to store up to 192 containers of spent nuclear fuel. With the assistance of environmental groups, neighboring residents lodged a legal complaint against the project. In a judgment dated January 2, 2006, the Bavarian Administrative Court rejected these complaints. An appeal was not accepted. The plaintiffs protested this decision with a complaint of non-admission to the Federal Administrative Court in Leipzig. On August 24, 2006, this motion was rejected.^[15] In addition to concern about catastrophic accidents in particular terrorist attacks, the opposition was motivated by fear that the interim storage facility might develop into an unplanned permanent storage facility, since even in 2005, despite many assurances, there still existed no permanent depository anywhere in the world for spent nuclear fuel, which requires safe containment for approximately a million years.

Weather tower

Since 1978, approximately one kilometer east of the nuclear power station, at 48°30'47" N, 10°25'13" E, has been the location of a 174 m tall steel and concrete tower with instruments for monitoring climatic conditions, known as the Meteo-Turm or Weather Tower. This tower also houses a ham radio digipeater with callsign DB0DLG for packet radio.

Incidents

In the early morning hours of January 6, 2008, Unit B of the Gundremmingen Nuclear Power Station was shut down as a precaution. The reason was an approximately 3% reduction in output by one of the low-pressure turbines; that corresponds to approximately 40 megawatts of output. The cause was a defective weld in a pipe, through which steam was reaching the condenser directly, without passing through the turbine rotors. To determine the cause of the drop in performance and repair the damage as well as to prevent any possible effects on the turbine, the unit was powered down. On January 8, the problem with the weld was corrected. The reduction in performance by the turbine had no safety implications for the assembly or the environment surrounding the plant. It was not subject to mandatory reporting. The reactor went back online on January 12.

During 2007, the oversight agency was informed of a total of nine incidents (5 in Unit B, 4 in Unit C). All were deemed "insignificant in terms of safety." Emissions of radioactive substances had in all cases remained under the permitted threshold, according to an annual statement to the press in 2008 by the technical supervisor, Dr. Helmut Bläsig.^[16]

Reactor data

The Gundremmingen Nuclear Power Plant has a total of three units:

• 
  The nuclear power plant
• 
  Units B and C
• 
  Close-up view showing steam venting

References

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