Storage of research reactor fuel elements in the Ahaus interim storage facility

Universities and research centres in Germany have been operating research reactors for decades. The neutrons provided in the reactors are used in basic research and for medical and industrial applications: from the production of radioisotopes for cancer therapy through to the improvement of lithium-ion batteries. The research reactors use fuel elements to produce the neutron flows needed for experiments and measurements. After they have been used, the fuel elements from the research reactors in Garching, Berlin and Mainz will be packed in CASTOR casks and stored in the Ahaus interim storage facility. After their interim storage, fuel elements will be disposed of in a repository for highly radioactive waste.

The place where CASTOR casks with fuel elements will be stored after they have been used must be stipulated in the applicable licensing procedure before research reactors can go into operation in Germany.

The Ahaus interim storage facility will be used to store fuel elements from German research reactors. Fuel elements from the research reactor that was operated in Dresden-Rossendorf between 1957 and 1991 have been stored at the Ahaus site, which is operated by BGZ, since 2005.

An agreement was reached with the Municipality of Ahaus as early as 1993 enabling fuel elements from German research reactors to be stored in the Ahaus interim storage facility, provided that a license is granted under nuclear law. On this basis, contracts were agreed between operators of the research reactors and the operator of the Ahaus interim storage facility concerning the future emplacement of research reactor fuel elements. These contracts are now coming into effect.

18 MTR 2 type CASTOR casks with fuel elements from the Dresden-Rossendorf research reactor are already being stored in the Ahaus interim storage facility (the double and triple stacked MTR 2 casks can be seen in the image surrounded by double stacked AVR/THTR type CASTOR casks)

Licensing procedure

Fuel elements from research reactors can only be stored in the Ahaus interim storage facility if licensed under nuclear law by the Federal Office for the Safety of Nuclear Waste Management (BASE).

The licensing procedures for the storage of fuel elements from the Garching, Berlin and Mainz research reactors were started in 1995. However, as it was foreseeable that the operators would not initially make use of a license, the licensing procedures were provisionally suspended around 2002.

Research Neutron Source Heinz Maier-Leibnitz (FRM II)

The licensing procedure for the storage of spent fuel elements from the “Forschungs-Neutronenquelle Heinz Maier-Leibnitz” (FRM II) was resumed in September 2014. The research reactor is operated in Garching near Munich and is a central scientific institution at the Technical University of Munich (TUM), which is of considerable importance in the national and international research landscape. FRM II has a contractual option for the storage of up to 21 CASTOR casks in the Ahaus interim storage facility. The transport of these casks is currently scheduled to begin in 2021.

As well as basic research, the FRM II is also used in areas such as the production of radioisotopes for radiopharmaceutical products to combat cancer or silicon doping for the semiconductor industry.

Further information on the Research Neutron Source Heinz Maier-Leibnitz (FRM II) can be found on the FRM II website.

BER II Research Reactor in Berlin

The licensing procedure for the storage of spent fuel elements from the BER II Research Reactor Berlin was resumed in May 2020. The BER II was operated by the Helmholtz-Zentrum Berlin (HZB) and was finally decommissioned in 2019. The HZB has a contractual option for the storage of up to nine CASTOR casks in the Ahaus interim storage facility. According to current planning, the HZB requires a maximum of three type MTR3 CASTOR casks to package the fuel elements from BER II. The HZB does not plan to transport fuel elements to Ahaus before 2023.

Further information on the Berlin Research Reactor can be found at the HZB website.

TRIGA Research Reactor of the Technical University of Mainz

The licensing procedure for the storage of fuel elements from the research reactor in Mainz (TRIGA) at the Technical University of Mainz (JGU) is currently suspended and will resume in due time.

The JGU has a contractual option for the storage of up to two CASTOR casks in the Ahaus interim storage facility.

Further information on the Research Reactor of the Technical University of Mainz can be found at the JGU website.

Casks for transport and storage

CASTOR MTR3

The thick-walled cast iron container body of the CASTOR MTR3 effectively shields the radiation coming from the inventory. The container’s lid system, which consists of solid steel lids, metal seals and screw fittings, safely and reliably encloses the fuel elements when they are transported and stored and dissipates the heat produced by the waste by transferring it through the inner structures and the container body.

As the fuel elements from the research reactors are considerably smaller than those coming from nuclear power stations, the dimensions of the CASTOR MTR3 are smaller than containers for fuel elements taken from nuclear power stations or vitrified waste block canisters from reprocessing.

The heat output of spent research fuel elements is also much lower. The CASTOR MTR3 is licensed for maximum heat output of around 0.29 kilowatts (kW)[1]. In comparison: The approval of the type HAW28M CASTOR cask for vitrified waste block canisters from reprocessing permits maximum heat output of 56 kW.

The CASTOR MTR3 was given a transport license in January 2019.

[1] Refers to the overall heat output with radioactive inventory from the FRM II.

Technical data

Loading capacity

  • KKE7 basket for FRM II: 5 fuel elements per cask
  • MTR basket for BER II: 33 fuel elements per cask
  • TRIGA basket: anticipated 16 fuel elements per cask[2]
  • Maximum output of heat (kW) and total activity (PBq):
    • FRM II: 0.285 kW and 3.96 PBq
    • BER II: 0.67 kW and 7.38 PBq

Dimensions and weight of the container in the storage configuration

  • Total height: 160 cm
  • Outer diameter 150 cm
  • Cavity height 92 cm
  • Cavity diameter 72 cm
  • Cask weight 16 t

[2] The MTR3 with the MTR and TRIGA baskets has not yet been approved.

Cask safety

CASTOR casks withstand extreme accident conditions. Numerous tests conducted over the last four decades have demonstrated how safe the casks are. CASTOR casks have undergone more safety tests than any other containers in the world.

Drop tests

Drop tests from different heights (7.5 m to 40 m) with varying impact conditions (horizontal, diagonal, vertical) compliant with IAEA (International Atomic Energy Agency) regulations. The cask manufacturer also conducted further tests in the early 1990s which went beyond the requirements of the licensing and approval authority. The cask remained sealed in all tests.

Fire tests

Thermal tests, such as fire tests and thermal load tests: These tests focus on cask temperatures. Computer simulations are now used to produce reliable predictions and in many cases have replaced drop and fire tests. The cask withstood temperatures without any damage.

Other tests

Tests which exceed official safety requirements. For example, an explosion of a fully-loaded liquid gas tanker next to a CASTOR cask. The test setup was heated up until the internal gas pressure caused the tanker to burst and the gas to explode. The cask penetrated the earth just a few metres away from the test setup. The cask remained sealed.

Safety during interim storage

In recent years, an additional protective wall has been erected to make interim storage even more secure. The image to the left shows barriers under construction in 2019; the image to the right shows the barriers after their completion in 2021.

BGZ interim storage facilities, such as the one in Ahaus, are operated in compliance with the highest safety requirements and permanently upgraded. Compliance with these safety requirements is constantly monitored by the supervisory authorities. No incidents of any kind that might pose any danger to people or the environment have occurred in the Ahaus interim storage facility during the around 30 years in which it has operated.

BGZ requires a license from the Federal Office for the Safety of Nuclear Waste Management (BASE) before it can store fuel elements from research reactors in the interim storage facility.

In the licensing procedure BGZ must, amongst other things, demonstrate that

  • the necessary measures have been taken in the light of the state-of-the-art in science and technology to prevent damage,
  • the fuel elements are adequately protected, for example, against terrorist attacks, and
  • personnel have the sufficient expertise and are reliable.

A license is only granted if all these requirements are met.

Throughout the time in which high-level radioactive fuel cells are being held in interim storage, BGZ ensures four central protection objectives are met at all times (subcriticality, heat removal, safe enclosure and shielding).

High-level radioactive waste: Safety through to final disposal

CASTOR casks containing high-level radioactive waste have been held at the Ahaus interim storage facility since 1992

In August 2015, the Cabinet of the Federal Government of Germany adopted the National Waste Management Programme for the responsible and safe disposal of radioactive waste in Germany. The public was extensively involved prior to this in the framework of a strategic environmental assessment. The public consultation process enabled public authorities and ordinary citizens to give their responses to the draft programme.

The strategy for the management of nuclear waste in the National Waste Management Programme for Germany was drawn up with the participation of the public and the federal states. The nuclear waste will be stored in the interim storage facilities pending final disposal.

The German Site Selection Act requires that a repository site is found for high-level radioactive waste by 2031. The repository will then be licensed and built. The repository is scheduled for commissioning around the year 2050. Please note that the law’s text is available in German language only.

The National Waste Management Programme provides for a receiving storage facility to be built at the repository site. This would create the conditions to commence the clearance of the existing storage facilities.

Interim storage at each site remains time limited.

Please note that the further information is available in German language only.

Dialogue and transparency

BGZ provided information at an early stage at the Ahaus site about the future storage of research reactor fuel elements.

This participative dialogue with the people in the region will continue: FRM II representatives and BGZ informed the local council, administration and mayor of Ahaus about the project progress in dialogue events in 2019 and 2020. An online event for all interested parties is now expected to take place in late summer 2021.

The dates of all future events will be published on this website.

December 2020: WDR report on the planned interim storage of fuel elements from FRM II in the Ahaus interim storage facility

Organisation

Cask manufacture

Universities / Research centres

Transport commissioned to the Ahaus interim storage facility

Procurement of casks

Acceptance and inspection of loaded casks

Storage of casks in interim facilities

Safe interim storage of casks

Transfer to the repository

Acceptance and inspection of casks

Operation of the repository at the repository site in compliance with the Site Selection Act

Storage in the repository

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