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Decommissioning

Decommissioning

Overview – Decommissioning of nuclear power plants in Germany

In 2010, a lifetime extension of German nuclear power plants by 8 or 14 years was determined by a modification of the atom law. Shortly after the reactor disaster in Fukushima, Japan in March 2011, after a short moratorium, the government decided to shut down 8 German nuclear power plants definitely.

As a consequence, the following NPPs lost their operating license as:

  • NPP Biblis, block A and B
  • NPP Brunsbüttel
  • NPP Isar, block 1
  • NPP Krümmel
  • NPP Neckarwestheim, block 1
  • NPP Philippsburg, block 1
  • NPP Unterweser
Since these power plants were in full operation before being shut down in 2011, taking time (for radiation decay) and according decontamination measures is useful and – considering radiation protection for the personnel – absolutely necessary.

Independently from the exit of nuclear energy, 4 German NPPs were already in decommissioning stage at this moment:
  • NPP Würgassen
  • NPP Stade
  • NPP Obrigheim
  • NPP Mülheim-Kärlich
and some research reactors.

For smaller NPPs of the 1st generation in Germany, decommissioning up to the greenfield has been successfully completed already (for example NPP Niederaichbach, NPP Kahl)

After preparing works like the removal of fuel elements and system decontamination, the actual decommissioning (depending on reactor type) is devided into 5 phases:

Phase 1: Decommissioning of installations which are not needed anymore for remaining operation
Phase 2: Decommissioning of large components, for example parts of the steam generator
Phase 3: Decommissioning of the reactor pressure vessel,
nuclear componentes …
Phase 4: Decommissioning of contaminated plant parts,
proof of non-contamination
Release of remaining structures from the
nuclear legislative control
Phase 5: Conventional building demolition
(More information can be obtained for example at Wikipedia.)

Being a specialised company for radiation measuring equipment,
S.E.A. GmbH supplies measuring systems which are particularly dedicated to the varied tasks of nuclear decommissioning, for example:
  • contamination monitors for release measurements
    of large wall and floor surfaces
  • release counters for inside and/or outside contamination control of pipes
  • special detectors based on gamma measurements
We are happy to develop measuring customer-specific measuring equipment according to your requirements and field of application.

We make radiation measurable.

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Measuring equipment for decommissioning

  • large-area detector PL 525
  • detector lift
  • γ-contamination monitor CoMo-300 G
  • pipe monitor (in development)

large-area detector PL 525
detector lift
γ-contamination monitor CoMo-300 G
pipe monitor

Click on the images to get more details on the right.
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Large-area y-detector PL 525

Large-area y-detector PL 525

The release measurement of a significant part of the large areas in a nuclear power plant is done by means of in-situ gamma spectrometry measurements with a high purity germanium detector. Not all surfaces and room areas can be checked for release measurement by this method. For that reason and in cooperation with the NPP Stade, we developed a plastic scintillation detector with 525 cm² detector surface, which can be used both manually and in combination with auxiliary handling equipment (trust system, detector lift). The detector system PL 525 has been qualified for this application.
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Detector lift

Detector lift
Basic version detector lift

maximum till approx. 4.75 m
maximum till approx. 4.75 m

with ceiling measuring feature
with ceiling measuring feature

detector also sidely movable
detector also sidely movable

measuring electronics and control unit of lift system
measuring electronics and control
unit of lift system

In order to check large areas without requiring physical strength of the employees, we developed a detector lift which moves the detector across the wall / ceiling. The measurements are stored in the system and transferred to a PC-system for evaluation. The detector lift was developed for NPP Stade, which is currently decommissioned, and is used there. Extensions with features to scan large areas automatically are in development.

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Contamination monitor
CoMo-300 G

γ-Kontaminationsmonitor CoMo-300 G

The use and function of e.g. a contamination monitor is different in case of decommissioning nuclear power plants. An example is the release measurement of large wall, floor or ceiling surfaces. Over decades, the walls have been painted with decontaminantion paint several times. Contaminations which are covered by a paint layer cannot be measured with a ß-measuring contamination monitor. For this special application, we now offer the established contamination monitor CoMo-300 not only in the basic version with a thin-layer plastic scintillation detector (α- and ß/γ) but also with a 20 mm thick plastic scintillation detector for pure γ-measurement.
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Pipe measuring instruments

Pipe measuring instruments

Pipe measuring instruments

Pipelines in which radioactive fluids were transported over many years during the active operation of a nuclear power plant, have to be decontaminated before disposal and be subject to release measurement after special treatments.
Depending on the quantity of waste, we can offer you manual or automatic measuring systems for ß- or γ-measurement. We use gas-free plastic scintillation detectors. Pipe detectors with several diameters are available.