Dismantling the activated carbon system and delay line in the Philippsburg 1 nuclear power plant
(KKP 1)

a project by KOBAU from Bremerhaven

The Philippsburg nuclear power plant (KKP) is located on the Rhine, around 30 kilometres north of Karlsruhe. EnBW produced electricity at this facility using a pressurised water reactor (Block 2, until 2019) and an additional boiling water reactor (Block 1, until 2011).

The Baden-Württemberg Ministry of the Environment granted EnBW the first decommissioning and dismantling permit for Block 1 in April 2017. Dismantling of the facility started in May 2017.

KOBAU, the specialist for power plant dismantling and member of ROBUR, took apart the activated carbon system and the delay line in Block 1 of the KKP between November 2019 and March 2020. KOBAU received strong support from SA Kerntechnik teams, a specialist for the dismantling of nuclear facilities and also a ROBUR partner company.

What are AC systems and delay lines?

Activated carbon (AC) systems and delay lines are parts of the off-gas cleaning facilities in nuclear power plants (NPP). In boiling water reactors, gases and volatile substances dissolved in the steam are selectively fed into an off-gas cleaning system located downstream of the turbine and the condenser.

Most of the radioactive substances decay along the connected delay lines. Xenon-133, for example, decays to 0.1% of its original activity with a delay of 40 to 60 days.

The AC system in KKP Block 1

The system was located in a room with floor space of 15 x 3.2 metres and a height of 23 metres.

The delay line consisted of 6 pipes with a diameter of 700 mm, a length of 6 metres each and a weight of 10,000 kg. The individual pipes were connected to the wall above each other. The 6 activated carbon tanks had a height of 18.6 metres and a diameter of 1.5 metres. Each of the tanks weighed a hefty 13,000 kg.

So it was a daunting project.

The dismantling strategy

Exclusively cold separation methods were used due to the radiological situation.

To reduce the local dose rate, the lower 3 pipes of the delay line were dismantled first, and the pipes were cut into approx. 1 metre sections. Our KOBAU colleagues professionally sealed the ends with foil to prevent the spread of contamination.

Standing 18.6 metres tall, the activated carbon tank was attached to a hoist, lifted, and then a ring measuring approx. 800 mm in width was cut off the lower part. The ring was sawed into 5 parts to fit through the narrow transport route.

Removal of two steel platforms, the ceiling-mounted crane rail and various small and measuring lines was performed immediately after dismantling of the activated carbon tanks. The KOBAU specialists dismantled the rest of the pipes in the delay line.

All waste materials were packed safely in steel boxes and handed over to EnBW.

In total, the KOBAU crew dismantled materials weighing 106,000 kg in five months:
A real success story for everyone involved – for EnBW and for KOBAU, specialist for services, operation and dismantling of nuclear facilities for more than 25 years.

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Dismantling the activated carbon system and delay line in the Philippsburg 1 nuclear power plant(KKP 1)

a project by KOBAU from Bremerhaven

What are AC systems and delay lines?

The AC system in KKP Block 1

The dismantling strategy

Who would you like to contact?

Gabriele Hetzner

Olaf Becker

Cristobal Lopez

Mark Oliver Passauer

Maik Voss

Manfred Hirt

Thorsten Kulik

Thomas Neudorfer

René Auringer

Kevin Crowley

Norbert Pfitzner

Fabian Strahl

Thorsten Nilles

Thomas Gröne

Justin Jones

Martin Skladal

Uwe Harlacher

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Silvia Kraus-Besendorf

Stefan Besendorf

Roland Schuldt

Manuel Kunert

Thomas Mannecke

Jan-Jörg Müller-Seiler

Tobias Gärtner

Roland Schuldt

Sebastian Albrecht

Amar Reddy

Javier Amelivia

Tim Petersen

Stefanie Weber

Jean-Philippe Enzer

Ernesto Mora

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Sascha Dilger

Maren Bögel

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Dismantling the activated carbon system and delay line in the Philippsburg 1 nuclear power plant
(KKP 1)