MicroStep technology in use for safe nuclear power plant decommissioning

Record time development, in operation since 2020: radiation measurement equipment at the Greifswald nuclear power plant

MicroStep technology in use for safe nuclear power plant decommissioning

Together with partners, MicroStep develops and produces two automated radiation measuring chambers for the German company EWN to dismantle the nuclear power plant in Greifswald/Lubmin

Published 02.03.2023 | Erich Wörishofer

Company profil:

EWN Entsorgungswerk für Nuklearanlagen GmbHLatzower Straße 117509 RubenowGermany

Entsorgungswerk für Nuklearanlagen GmbH (EWN), based in Mecklenburg-Western Pomerania, is a state-owned company specialized in the dismantling and disposal of decommissioned nuclear power plants. For example, the Greifswald/Lubmin nuclear power plant in Mecklenburg-Western Pomerania and Rheinsberg nuclear power plant in Brandenburg are among the activities of EWN GmbH and its more than 2,000 employees. The company's other tasks include the disposal and interim storage of spent nuclear fuel and radioactive residues, the organization of final disposal and the associated delivery management of radioactive waste for the public waste management authorities.

www.ewn-gmbh.de

Radiation measuring chamber for the Greifswald nuclear power plant  
Together with technological partners, MicroStep developed and produced two radiation measuring chambers, type RTM643NG, which are operated by Entsorgungswerk für Nuklearanlagen GmbH in Greifswald ( Mecklenburg-Western Pomerania).

The clock is ticking: From today's perspective, the nuclear phase-out in Germany has reached its final deadline with the extension of the operating life of nuclear power plants until April 15. Regardless of whether the operating time is adjusted again or whether other countries continue to rely on nuclear power – the day will come when the technology must be dismantled in a costly and safe manner. MicroStep technology plays a central role in this process in Germany.

With its diverse solutions of CNC-controlled high-end cutting systems with plasma, laser, waterjet and oxyfuel cutting technology, MicroStep is represented in more than 50 countries in many hundreds of productions worldwide. Since cutting system, control system and software come from a single source, MicroStep is also a sought-after partner for special solutions related to cutting and beyond. For example, when it comes to controlling hydropower plant turbines or various robot applications – but MicroStep technologies are also used in the dismantling of nuclear power plants.

The story began with a project in Slovakia in the mid-2000s: solutions were sought for the disposal of Unit A1 of the Jaslovské Bohunice nuclear power plant, 60 km northeast of the Slovak capital Bratislava. At that time, in close cooperation with technological partners, a portfolio of equipment was developed to measure radiation from nuclear waste stored in containers (using gamma probes) and to measure the radioactivity of the exhaust air in the plant's stacks. Since 2007, MicroStep has delivered dozens of different systems to nuclear waste management facilities, nuclear institutes and power plants – most of them to Central and Eastern Europe.

EWN takes care of dismantling, disposal, storage and other organizational tasks

Since 2020, with the delivery of special radiation measuring chambers to EWN GmbH, MicroStep technology has also been in use in Germany for the dismantling of nuclear power plants. The Entsorgungswerk für Nuklearanlagen GmbH (= disposal plant for nuclear facilities Ltd.), formerly known as Energiewerke Nord (= energy plants north), is a state-owned company that specializes in the dismantling and disposal of decommissioned nuclear power plants. Since 1995, EWN has been responsible for the former Greifswald/Lubmin nuclear power plants in Mecklenburg-Western Pomerania and Rheinsberg in Brandenburg, among others.

This activity is time-consuming. Because the service life of a nuclear power plant does not end with its shutdown. Depending on the decommissioning method, the service life may even be longer than the active operation in exceptional cases. Whether immediate decommissioning or exceptional case – the process takes many years in each case.

From nuclear reactors to individual concrete elements – everything must be checked for radiation

Finally, the entire facility must be dismantled. The nuclear power plant is much more than the nuclear reactor itself. There are many components such as pumps, pipes and concrete structures that can be safely recycled by conventional means as scrap metal or as crushed concrete for road construction. Thus, on average, about three-quarters of the materials collected are recyclable. The remaining materials are radioactive to varying degrees and must be decontaminated where possible or, as in the case of spent nuclear fuel, safely kept and stored as radioactive waste.

Recycling or storage - it all depends on a careful test procedure. Comprehensive radiation measurement ensures that the materials intended for recycling are not (no longer) hazardous, that the decontamination process has been properly carried out, and that the storage containers are impermeable to radioactive waste. Special machine systems are used for these tasks to protect people, animals and the environment.

 

"With the experience from previous projects, we were able to develop an individual and highly automated solution with our partners, which offers the greatest possible safety to the personnel and, of course, the certainty that the recyclable materials are really harmless and only the really necessary materials have to be disposed as radioactive waste!"

Dr.-Ing. Alexander Varga,

Head of Research & Development | MicroStep

 

Close development partnership between MicroStep and other technology companies

To monitor and safeguard the goods, EWN operates two radiation measuring chambers in Greifswald. In 2020, the existing devices had reached the end of their service life and had to be replaced. The chambers used were discontinued models; accordingly, the market was explored for modern and durable solutions. EWN's general supplier of radiation measurement equipment, the internationally active company Mirion Technologies (Canberra) GmbH, brought suitable partners on board – MicroStep and TechMart s.r.o., a specialized supplier of radiation measurement technology. Together, a new-generation measuring chamber, the RTM643NG, was developed in record time. Two complete systems were finally manufactured. These have been reliably in use ever since.

Automated solution for maximum safety

Each of the two chambers is equipped with a chain conveyor that transports containers of material (concrete rubble, soil, metal parts or used protective equipment) to and from the measuring chamber itself. On its way to the chamber, the container is automatically weighed and must pass through a gate of light beams and sensors. This ensures that the permissible size is not exceeded and that protruding parts cannot collide with the measuring chamber. Each measuring chamber is shielded with special lead plates supplied by TechMart, which are embedded in a steel frame. In the walls and doors on the inside are extensive, highly sensitive scintillation counters for radiation measurement, 16 in each chamber, arranged in a special measurement geometry.

The system is operated outside the measuring chamber on a free-standing console equipped with a touchscreen featuring a modern user interface. In standard automatic mode, all that is required is to place the container on top and issue the "start" command. However, if required, the operator can also manually control the position of the scale table, the container and the front door. The measurement itself typically takes between 10 and 30 seconds and provides one of two results: The radiation level is either below the strict limit set by the German government and the material can be released for general recycling, or the limit has been exceeded and the material must be treated as radioactive waste.

The first chamber was delivered at the end of 2020, the second one year later. Both have been in continuous operation since then. "MicroStep is proud to contribute to the safe dismantling of German nuclear facilities. With the experience from previous projects, we were able to develop an individual and highly automated solution with our partners, which offers the greatest possible safety to the personnel and, of course, the certainty that the recyclable materials are really harmless and only the really necessary materials have to be disposed as radioactive waste," says Dr.-Ing. Alexander Varga, co-founder and head of research & development at MicroStep.

Video report on NDR

 

In its television broadcast of December 5, 2022, the German television channel NDR reported, among other things, on the decommissioning of the Greifswald nuclear power plant and from minute 25:00 - 26:45 also on the radiation measuring chambers used by MicroStep. Click here for the video clip from NDR.

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