Geesthacht research reactor

from Wikipedia, the free encyclopedia
Geesthacht research reactor
Research reactor Geesthacht (right) next to the Krümmel nuclear power plant (left)

Research reactor Geesthacht (right) next to the Krümmel nuclear power plant (left)

location
Research reactor Geesthacht (Schleswig-Holstein)
Geesthacht research reactor
Coordinates 53 ° 24 '16 "  N , 10 ° 25' 35"  E Coordinates: 53 ° 24 '16 "  N , 10 ° 25' 35"  E
country Germany
Data
operator Helmholtz Center Geesthacht - Center for Materials and Coastal Research (HZG)
start of building 1956
Installation FRG-1 : October 23, 1958
FRG-2 : March 15, 1963
Shutdown FRG-1 : June 28, 2010
FRG-2 : June 1, 1993
Reactor type Swimming pool reactor
Thermal performance FRG-1 : 5 MW
FRG-2 : 15 MW
Neutron flux density FRG-1 : 1.4 × 10 14  n / (cm 2 s)
FRG-2 : 1.0 × 10 14  n / (cm 2 s)
Website Info pages at the HZG
was standing June 28, 2010

The Geesthacht research reactor is the name given to two research reactors that were operated on the site of the Helmholtz-Zentrum Geesthacht (HZG) in Geesthacht .

The Geesthacht-1 research reactor ( FRG-1 ) ran from 1958 to 2010 and had a nominal output of five megawatts (MW). The research reactor Geesthacht-2 ( FRG-2 ) with an output of 15 MW was in operation from 1963 to 1993. Both reactors were among the largest of their kind in Germany . Between 2000 and 2010, the FRG-1 was also the oldest operating nuclear reactor in Germany. The neutrons produced were used exclusively for basic research in materials science and medicine .

All reactors have now been shut down. Dismantling is planned and could Template: future / in 5 yearstake place by 2030 .

history

After the founding of today's Helmholtz-Zentrum Geesthacht - Center for Material and Coastal Research GmbH as GKSS ( Society for Nuclear Energy Utilization in Shipbuilding and Shipping mbH ) in 1956, the research reactor FRG-1, together with the associated technical facilities, was built in just 18 months completed. The reactor was commissioned on October 23, 1958 as the third large nuclear reactor (with an output of over 50 kW) in Germany after the research reactors in Munich ( FRM ) and Rossendorf ( RFR ).

On March 15, 1963, the second reactor, FRG-2, went into operation. With a maximum thermal output of 15 MW, it also served as a neutron source for material tests until it was switched off on June 1, 1993 . Investigations into the safety of nuclear facilities were also carried out at this research reactor. Since their commissioning, both reactors have been adapted to the increased safety requirements, the current state of science and technology and new research objectives. In 1964, the facility for zero-power experiments was added as the third reactor , in which fuel rod assemblies were tested.

Research ship Otto Hahn in 1970

The first concrete result of the research was the nuclear power drive for the research ship Otto Hahn , which was launched on June 13, 1964 and completed its first test drive on October 11, 1968. Ultimately, it was decided to use an advanced pressurized water reactor (FDR) as the drive. The cargo ship's nuclear drive was decommissioned on March 22, 1979 after a total of 650,000 nautical miles, the ship was then converted and ran with a conventional diesel drive until 2009.

In the seventies two more ships with the name "Nukleares Container-Schiff" (NCS 80 and NCS 240) were planned, but never built, because despite government subsidies no shipowner could be found who wanted to commission such a ship.

In February 1991 the research reactor FRG-1 was the first nuclear reactor in Germany to be converted from highly enriched uranium (93%) to weakly enriched uranium (20%). In addition, the reactor core was made smaller in order to increase the neutron flux . In the last few years of operation, the research reactor was available to scientists for around 250 days a year. At the beginning of each year, the reactor was shut down for about six weeks for safety reviews and adjustments.

On the fiftieth anniversary of commissioning, the operating shareholders from the federal and state governments decided on October 23, 2008 to shut down the reactor in two years. On June 28, 2010, the research reactor FRG-1 was finally shut down. The dismantling of the plant is expected to take ten years and will cost around 150 million euros.

FRG-1

construction

The research reactor FRG-1 was a material test reactor of the swimming pool reactor type . In the middle of the 33 × 16 m reactor hall there was a reactor basin that was open at the top, the reactor core hung at a depth of about seven meters and was suspended from a bridge that spanned the basin. The lower part of the pool wall consisted of a 180 cm thick layer of heavy concrete with a density of 3.5 g / cm 3 , a 60 cm thick layer of normal concrete (density 2.3 g / cm 3 ) and a 0.5 cm layer in between thick steel tub.

The reactor was cooled using two separate cooling circuits , the primary circuit for direct heat dissipation from the reactor core and the secondary circuit for heat dissipation to the environment via a cooling tower . The two cooling circuits were separated from one another by a plate heat exchanger. The operating basin of the primary circuit had a volume of 140 m 3 , with the water heated from around 40 ° C when entering the water basin to around 46 ° C when exiting the reactor core. The water flow rate was around 740 m 3 per hour.

The research reactor FRG-1 recently used weakly enriched U 3 Si 2 as nuclear fuel, with eight fuel assemblies and four control fuel assemblies in use. Each fuel element contained 410 grams of uranium -235 embedded in 23 individual fuel plates, each control element contained 320 grams of uranium-235 in 17 fuel plates. As absorber material is hafnium , as coolant and moderator used demineralized water. At full power, around six grams of uranium-235 were consumed per day, of which around five grams were split and one gram was converted into uranium-236.

The neutrons produced reached the adjacent test hall through nine beam tubes, where they were available at the experimental facilities. For focusing the neutrons were Beryllium - reflectors used. The undisturbed neutron flux was 1.4 × 10 14 n / cm 2 s. In addition, there were several positions directly on the reactor core for sample irradiation.

Experimental facilities

The following experimental facilities were recently set up at the FRG-1 research reactor:

Surname description
GENRA-3 Neutron radiography and tomography for non-destructive irradiation of components to find material defects
INAA Neutron activation analysis to determine the chemical composition of samples
TEX-2 Diffractometer for the analysis of textures and crystalline areas e.g. B. in rock samples
NeRo / PNR Neutron reflectometry for the investigation of thin layers (1–100 nm) in plastics and metallic materials
SANS-1 / SANS-2 / DCD Small angle neutron scattering for the investigation of defects and phase transitions in solids and of structures and kinetic phenomena in liquids and polymers
FSS / ARES-2 Diffractometer for residual stress analysis for the non-destructive investigation of residual stresses inside materials and components
GBET Irradiation facility for basic research in boron capture therapy to combat tumor cells
Rödi Single crystal diffractometer for additional X-ray analyzes of phases, residual stresses and textures as well as reflectometry examinations
HOLONS Holography and neutron scattering for simultaneous examinations with laser beams and neutrons on holographic grids
POLDI Diffractometer for polarized neutrons to study magnetic materials

FRG-2

The research reactor Geesthacht-2 (FRG-2) with an output of 15 MW was in operation from 1963 to 1993.

It was also a swimming pool reactor with a somewhat lower maximum neutron flux density of 1 × 10 14 n / (cm 2 s). The reactor was started up for the first time on March 16, 1963 and then operated as a material test reactor for 30 years. On January 28, 1993, the application for decommissioning was made. On January 17, 1995, approval was given for decommissioning and partial dismantling. However, the shutdown could not be carried out at first because the FRG-2 shared the reactor pool with the FRG-1.

Reactor monitoring

Surroundings

The area around the research reactors was continuously monitored within a radius of 25 km for possible exposure to radioactive substances from 50 measuring points. In addition, soil, plant and water samples were taken regularly. The direct radiation exposure from the research reactor was so low in the vicinity of the facility that it could not be detected within the fluctuations of the natural radiation exposure.

investment

The facility was monitored particularly for the release of radioactive substances in the exhaust air and waste water. In addition, the personal dose , i.e. H. the level of radioactive radiation exposure of each employee, measured. The mean annual radiation exposure was one millisievert (mSv), far below the maximum permissible exposure of 50 mSv according to the Radiation Protection Ordinance. Materials that could have been radioactively contaminated through operational use were checked for activation and contamination , sorted out in the case of weak and medium radiation and stored in barrels until they were finally stored. The fuel elements were used up after a year of use and were stored in a water basin until they were finally disposed of in the USA .

Effects on the environment

Location of the Geesthacht research reactor (GKSS) next to the Krümmel nuclear power plant (KKK) opposite the Elbmarschen

The two research reactors FRG-1 and FRG-2, together with the Krümmel nuclear power plant, are often suspected to be the cause of the significant accumulation of leukemia diseases in children in the Elbmarsch leukemia cluster . However, several studies have not yet been able to provide any evidence that one of the systems could be the cause of the disease.

This attribution of the cause is very controversial. A suspected fire incident at the GKSS in 1986, millimeter-sized ceramic balls found in the area, which are suspected to be pac balls made of nuclear fuel, as well as “secret nuclear special experiments on the GKSS site” are discussed.

See also

Web links

swell

  1. ↑ http://www.ndr.de/nachrichten/schleswig-holstein/Abbau-FRG-1-Geesthacht-Unterlagen-oeffnahm,forschungsreaktor104.html
  2. ^ Otto Hahn (former research ship) , Geesthacht City Lexicon
  3. ↑ Information on the container ship NCS-80  ( page no longer available , search in web archives )  Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice. , Federal Archives@1@ 2Template: Toter Link / www.bundesarchiv.de  
  4. ↑ a b Research reactor finally shut down , Welt Online from June 28, 2010
  5. ↑ a b nuclear power plant is switched off , taz of October 24, 2008
  6. ↑ Federal Office for Radiation Protection : List of nuclear facilities ( memento from January 26, 2012 in the Internet Archive ) '
  7. ↑ Covered up nuclear accident / SuperGAU in the FRG by Detlef zum Winkel, Konkret issue 12/2004
  8. ↑ Willi Baer, ​​Karl-Heinz Dellwo: Better to be active today than radioactive tomorrow III - The cancer cases in the Elbmarsch / The GAU in Fukushima. In: Willi Baer, ​​Karl-Heinz Dellwo (Ed.): Library of Resistance. Vol. 23, Laika-Verlag, Hamburg 2012, ISBN 978-3-942281-02-7