Dismantling control rods Grafenrheinfeld nuclear power plant

Dismantling control rods Grafenrheinfeld nuclear power plant

27 March 2021

In cooperation with our German partner Höfer & Bechtel we have developed a process for decommissioning control rods from pressurised water reactors. Together we successfully removed the control rods of the Grafenrheinfeld Nuclear Power Plant.

Savings of 10% storage space and costs due to smart packaging

Cutting, sampling, characterisation and packaging by NRG and Höfer & Bechtel

Applicable to other pressurised water reactors

Teams NRG and Höfer & Bechtel

NRG and Höfer & Bechtel’s partnership is characterised by:

  • Years of experience in developing remote-controlled tooling for use in the nuclear industry
  • Team of engineers used to working in nuclear installations
  • Experts in the field; the right licenses, expertise and facilities
  • Radiochemical analytical capacity
  • Able to carry out the entire process together, from cutting, sampling, transport and from characterisation to packaging. Unique in the nuclear world.

PreussenElektra, an introduction

- Energy supplier in Germany for nearly 100 years
- Operates 7 nuclear power plants in Germany
- Mission is nuclear safety
- Successful operation and decommissioning of nuclear power plants

One of PreussenElektra's nuclear power plants, Grafenrheinfeld, had to be decommissioned in 2017. PreussenElektra contracts NRG and Höfer & Bechtel to dismantle specific nuclear components in a professional and safe manner.

The challenge

NRG and Höfer & Bechtel have been assigned to dismantle, sample, characterise and package more than 100 control rods in special containers. The project had a number of challenges:

- Disassemble under water as efficiently as possible
- Taking samples of the different materials of the control rods
- Package as efficiently and safely as possible
- Minimal water pollution
- Complete characterisation of the control rods
- The work in the plant had to be carried out on schedule

Smart and safe loading

The biggest challenge was the packaging method, as we wanted to use as little space as possible while keeping the dose load for the employees as low as possible.

We worked out how best to cut the control rods for packaging in special containers. We have designed and built our own instruments based on this concept.

Thanks to the intelligent packaging concept of Höfer & Bechtel, we have used about 10% fewer containers than previously thought. As a result, the storage costs are lower. A significant saving!

Sampling & characterisation of the control rods

Another major challenge during the project was the sampling and characterisation of the control rods.

A control rod consists of a stainless steel outer jacket with an absorber core of a silver, cadmium and indium alloy. Both materials had to be sampled separately. NRG has developed special sampling equipment for this purpose that can take samples from both the outer jacket and the absorber. This enabled us to take precise samples underwater. Subsequently, the highly radioactive samples were transported to our radiochemical laboratories in Petten for extensive radiochemical characterisation.

Stronger together

The collaboration between NRG and Höfer & Bechtel was a perfect combination of expertise. We have been able to do the complete dismantling from cutting to radiochemical characterisation to packaging. Few parties on the market can deliver this entire process. That makes our collaboration strong and unique. Together we form a one-stop shop for the nuclear world.

“We have worked with Höfer & Bechtel for several projects over many years now. We know and trust each other’s expertise and our cooperation works very smoothly.” Werner Schuurman, NRG

Qualified techniques and procedures

The technology that we developed has been approved for nuclear use by the German TÜV SÜD. This is an independent institute in the field of safety, security and sustainability.

With this qualified approach we can also easily use our method for other (German) pressurised water reactors.

Satisfied customer and next assignment

Höfer & Bechtel and NRG have completed the order for PreussenElektra to their satisfaction.

Some great results are:
- within the deadline
- cost savings of 10% due to a smart packaging concept
- safe and responsible

All documentation for the completion has been accepted by the German government. In addition, PreussenElektra asked the NRG and Höfer & Bechtel team for a next assignment, the radiochemical characterisation of the reactor vessel and biological shield for 5 power stations.

Curious how we handled this case?

Read more about the case Decommissioning of 5 Preussen Elektra Nuclear Power Plants.

Please contact

Do you need help with one or more steps of decommissioning? I would like to tell you more

Marieke Schopman
Cluster Manager
T. +31 (0)6 1025352
M. m.vangemert@nrg.eu