tirsdag den 21. november 2017

Skal NORM-Affald fra Olie- og Gasboringer sprøjtes i Havets Undergrund?


Se opdatering 23.11.17 uddybende svar fra Gerhard Schmidt nederst OG DR 29.11.17


"Olieindustri ønsker hjælp til radioaktivt affald" kunne man læse på DR.dk 17.11.17, hvor direktør Martin Næsby fra Olie Gas Danmark efterlyser løsninger for, hvordan farligt olie-affald skal opbevares.

I et notat, fortæller DR, rejser olieindustrien flere spørgsmål om, hvordan regelgrundlaget er, hvis virksomheder som Mærsk ønsker at eksportere deres radioaktive affald til udlandet.

Brancheorganisationen spørger også, hvorvidt og hvordan olieindustrien kan få mulighed for at sejle radioaktivt affald ud på havet igen og sprøjte det ned i undergrunden.

I Ingeniøren 17.11.17 afviser lektor Steffen Foss Hansen på DTU Miljø, Institut for Vand og Miljøteknologi, forslaget: "Så snart, man tager sådan nogle materialer op, som ikke kan bruges til noget, så bliver de redefineret som affald. Og man må ikke putte affald ned i undergrunden."


Tysk ekspert: "Fast, cheap and dirty should not be the preferred management strategy in this case."

Jeg har præsenteret Næsbys forslag om sprøjtning af NORM affald i havets undergrund for pensioneret seniorforsker og kemiingeniør Gerhard Schmidt, der mens han arbejdede på det tyske Öko-Institut i Darmstadt, lavede et arbejdspapir til NOAH om det danske radioaktive affald på Risø. Jeg har også interviewet Gerhard Schmidt om Kvanefjeldsprojektet i Grønland (REE/uranmine).

Gerhard Schmidt skrev dd:


Hi Anne,

in oil and gas drilling natural radionuclides such as radium-226 and lead-210 are enriched on surfaces of the equipment. The radionuclides are relatively tight fixed to surfaces and are rather immobile. When handling the equipment exposure to direct radiation and, if surfaces are scraped or if the material is welded, by inhalation is relevant.

Dumping this equipment to the sea is not a viable waste management option. Firstly, the dumping of wastes to the sea is simply generally forbidden. And worn equipment that is not usable any more clearly is waste, on which the sea dumping ban applies.

And it makes no sense as it disperses the radionuclides in the sea. Re-enrichment of those nuclides in biomaterial, such as fish and crustacea, are extremely high (e.g. for lead-210 or actinium), so that the resulting ingestion doses for the consumption of those are very high. So dilution is only the first step, in the following steps this dilution is (over-) compensated by those re-enrichment effects. So with a view on the ecological consequences sea dumping is also not a sustainable waste management option in that case.

Methods exist that can remove those nuclides from the surface and enrich the nuclides in the material that is used for removal (decontamination). Methods such as sand-blasting or electro-surface-removal can remove most of the bounded radionuclides and enriches those in the sand (sand-blasting) or in the sludges (electro-polishing), resulting in smaller amounts of wastes to be managed. The so cleaned steel equipment can be re-melted and re-used then.

A small part of the contaminated equipment cannot be decontaminated in that way (e.g. equipment with very rough surfaces or which surfaces are inaccessible for treatment). Those smaller parts of the contaminated equipment can be melted in specialized and radiation controlled melting facilities (e.g. operational in Sweden and Germany). During steel melting radium is nearly fully enriched in the slag of the melting process. Furnace slags from such melting facilities should be handled as radioactive wastes if certain nuclide concentrations are exceeded.

As this kind of contaminated equipment are not of a large inventory those treatment stages should not be seen as on a national level because setting up the required special equipment is rather costly (per ton of material). As many countries have these problems the oil and gas industry should act on a European level.

Fast, cheap and dirty should not be the preferred management strategy in this case.

brgs,

gerhard

Opdatering 23.11.17 - Uddybning fra Gerhard Schmidt til mig:



Hi.

  1. No matter how this would be done: it is still dumping. In this case: sophisticated dumping, as it requires technologies that are not readily available so far.
  2. The safety concept for this bases on the strong retardation potential of the seafloor material(s), if undisturbed. The main requirement therefore is to proof that the seafloor remains undisturbed over the necessary enclosure time. Radium-226 as the main contributor to doses and as precursor of the decay chain has a half-life of roughly 1.600 years. A safety analysis for this technique would have to demonstrate that the sea floor encloses the radionuclides for roughly 20.000 years. Given the limited knowledge in this part of the world (geology has mainly focused on the underground on land) long-term predictions of this duration for the seafloor at the dumping location are at least a rather sophisticated approach. The very long-term modelling of erosion/sedimentation on the seafloor and scientific evidences, on which this modelling can be based on, including such natural events like glaciation that are to be expected within this time frame, are an open issue.

In the past, simple ideas sometimes ran into most complicated scenarios. In my view, this proposal has the potential to turn into a real scientific nightmare – and to end as a huge white elephant.

Compared to this, decontamination of these materials (and their re-use following successful decontamination) is a rather well-known and simply controllable technology.

brgs,
Gerhard

Citat slut

Skrevet af Anne

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