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Predisposal-waste processing:

Feedback of the Dutch historical waste management program

Gaël MENARD1, Bas JANSSEN1, Sander NIEVAART1, Aliki van HEEK2

1Nuclear Research and consultancy Group, Petten, The Netherlands2IAEA, Vienna, Austria

E-mail corresponding author: menard@nrg.eu

Abstact:

The current strategy includes the sorting of the historical waste drums from the HFR on the Petten site into 3 cat-egories of waste, primarily according to their respective activities: Low level and two intermediate levels activity (“Intermediate low” and “intermediate high”). Each category will follow specific routes (direct storage or 'super-compaction', cementation and storage). The resulting challenge for the Petten site lies on the process steps that consists of segregating, sorting, characterizing and packaging each drum. A system of family has been estab-lished: A family is represented by one waste stream i.e. including identified materials with a known irradiation history/cooling time and/or contamination. To build the safety case required by the regulator and the storage fa-cility, information were retrieved from the archives and coupled with calculated nuclides vectors and high reso-lution gamma measurements. As the waste streams considered are solid material, homogeneity and 'repre-sentability' of measurement/sampling should be challenged and assessed. A inter-comparison is planned by prac-ticing destructive analysis and performing some extra-measurements on certain pure beta-emitters such as Fe-55 and Ni-63. The resulting comparison is aimed to indicate error margins of the respective nuclide vectors to as-sess its range. The foreseen development of the project is to proceed from simpler family to more complex fami-lies (containing leftovers of fuel or not documented at all). This way NRG will gain in know-how in terms of footprint reduction and, in parallel, increase the complexity of the drums content and further breakdown of waste streams. The waste sorting of the so-called first family (representing drums containing the old reactor vessel dis-mantled and replaced in 1984) occurred over the past months.

Since the commissioning over fifty years ago of the High Flux Reactor, used for isotope production for medical purposes as well as material research, and the Low Flux Reactor, used for educational purposes, in Petten, Netherlands, radioactive waste has been produced. That waste, and radioactive waste from other Dutch producers of radioactive waste, e.g. hospitals and laboratories, has been stored for many years in the dedicated surface storage facility at ECN/NRG’s research site, the Waste Storage Facility (WSF).

In its ‘Memorandum on Radioactive Waste’, the Dutch government stipulated that from 1984 all the waste produced in the Netherlands must be collected, processed and stored by a central organisation. The Central Organisation for Radioactive Waste (COVRA) was established for that purpose. Until the early 1990s, COVRA was based in Petten, with the WSF serving as ‘national storage facility’. Thereafter COVRA moved to Nieuwdorp (Zeeland).

Although already hundreds of drums of low and medium activity historical waste were transferred from the WSF in Petten to the COVRA premises in Nieuwdorp, the WSF still stores low and intermediate level waste with medium and high activity radioactive and fissile material containing , historical waste (approx. 1700 cans) and operational waste that will be disposed of once it is sufficiently decayed. The intention was to move this waste from Petten once COVRA had a special facility ready for it there. This was the case in September 2003

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when the High activity Treatment and Storage Building (HABOG) was opened at COVRA. Thereafter, NRG started the Radioactive Waste Project (RAP).

The RAP project rapidly revealed that the storage containers holding the medium and high activity waste in the WSF did not comply with the packaging requirements imposed by COVRA for long-term storage. This was because the historic waste from Petten dated from the 1960’s and 1970’s when different materials and parts of varying radiation levels were stored together. COVRA’s waste acceptance criteria required sorting, repackaging and conditioning of that waste. However, neither COVRA nor NRG had suitable instruments and technology available for that purpose.

As a consequence, the RAP project was re-directed and now consists of the following elements:

Developing equipment for sorting, separation, characterizing and packaging of the historic waste to facilitate transportation and guarantee waste acceptance at COVRA;

Adapting existing laboratories at Petten to implement the project safely and responsibly Arranging safe transport in containers specially developed and certified for the purpose.

The ‘Intermediate Level’ waste is cemented and compacted in Belgium to make it suitable for storage in the HABOG facility at COVRA.

A helicopter view of the process is given figure 1.

Figure 1: Logistic of the sorting of the waste drums

The current strategy of the RAP project includes the sorting of the historical waste drums from the HFR at the Petten site into 3 categories of waste, primarily according to their respective activities: Low level and two intermediate levels activity (“Intermediate low” and “intermediate high”). Each category will follow specific routes: either direct storage or ‘supercompaction‘, cementation and subsequent storage at the COVRA premises.The challenge for the Petten site lies in the process steps consisting of segregating, sorting, characterizing and packaging each of the waste containers remaining in the WSF. For that purpose, waste families have been distinguished: A waste family is represented by a particular waste stream with similar characteristics, e.g. identified materials with a known irradiation history/cooling time and contamination.To build the safety case required by the Dutch regulator and COVRA, information has been retrieved from the archives and coupled with newly calculated nuclide vectors and high resolution gamma measurements. As the waste streams considered consist of solid material, homogeneity and representability of measurement/sampling could be challenged. Destructive analysis and performing measurements on certain pure beta-emitters such as Fe-55 and Ni-63

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are nonetheless planned. The resulting comparison is aimed to indicate error margins of the respective nuclide vectors to assess their ranges.A picture of the VINISH (for inspection and before transport) is given figure 2.

Figure 2: VINISH: High resolution gamma spectrometer

Figure 3 and 4 offer an insider view of the drums content and of its segregation.

Figure 3: Content of a historical waste drum disposed on the segregation table inside a hot cell

Figure 4: Example of a drum to be sorted and sorting process

The foreseen development of the project is to proceed from simpler waste families, with little cross contaminations to more complex families, which may contain leftovers of fuel-residue or which have not been documented in the past. This way NRG will gain knowledge about the drums’ sometimes complex contents, manage the further breakdown of waste streams, and reduction of the footprint of the radioactive waste.

Over the past months the waste sorting of the so-called first family was performed, representing drums containing the old reactor vessel which was dismantled and replaced in 1984.