Pubblichiamo oggi le trasparenze della conferenza “Le scorie dell’energia. Come chiudere il ciclo di una fonte?” svoltasi lo scorso 20 gennaio 2016 nell’ambito della rassegna “Energia, Società e Ambiente“, promossa da dai Dipartimenti di Studi Umanistici e di Fisica dell’Università di Trieste, da Sissa Medialab, Elettra-Sincrotrone, Ceric-Eric, Comitato Nucleare e Ragione, Nuclear Italy Research Group. Il video integrale dell’intervento del dott. Totaro è inoltre disponibile sul canale Youtube del Comitato Nucleare e Ragione.
[a storyapparently paradoxical of “nuclear repositories” in a “100% renewable” Country]
This article was originally published in Italian on the 7th of July, 2015.
Electricity production in Norway is almost 100% renewable: about 97% is hydropower, the rest comes from natural gas (just under 2%) and wind (just over 1%), “a little bit” from biomass and waste incineration; “traces” of production from solar, coal and oil are also present.
So there are no nuclear power plants in Norway. There has been a few discussions in recent years, chasing some innovative ideas based on the use of thorium; but for now, everything is silent – or rather, it is on the paper at proposal level. There are, instead, two research reactors still operating, the heavy water boiling reactor (HBWR) at Halden and the JEEP II at Kjeller; while two other are “retired” since long time, JEEP I and NORA. (As a mere curiosity the “retired” JEEP I coming into operation in 1951 was the first reactor operating in Europe, outside the borders of Great Britain and France, and the Soviet bloc.)
As in virtually all developed countries, nuclear technology finds application in Norway also in the medical field (e.g. radio-diagnostic and radio-pharmacology) and in the industrial field (e.g. NDT, and the treatment and storage of radioactive waste). Monitoring of all these activities is in accordance with international regulations and it is up to Statens strålevern, namely the Norwegian Radio Protection Authority (NRPA).
In January 2011 IFE’s inventory  recorded a total of some 18 tons of irradiated material (inclusive of the fuel inside the reactors still operating) – a volume easy to manage, even taking into account concrete and various structures with which this fuel is “packed”; since, for example, the density of U238 metallic is about 19 t/m3.
Thus, it would appear that there is not a lot of work for the NRPA. Actually, in Norway radioactive wastes offer volumes far more interesting, soon as you move from the storage of spent nuclear fuel to that of Naturally-Occurring Radioactive Materials (NORM).
Although, in fact, it does not use large amounts of oil for electricity generation, Norway is one of the largest oil producers in the world (just under 3% of the total, in 2013). And oil extraction – like any other mining activity, refining or processing of raw materials – involves a variety of by-products, some of which are radioactive, as they contain radioisotopes that abound in the Earth’s crust . Natural gas extraction is going great too; indeed, in many respects even better than oil: before the European embargo to Russia, Norway was the second largest supplier of natural gas to the EU .
Since January 1st, 2011, a new regulation is in force for which the treatment and management of radioactive waste – as well as monitoring and contrast to radioactive pollution – are under the same regulatory framework of all other pollutants and hazardous waste (cf. Pollution Control Act, 1981). The regulation provides, among other things, two sets of criteria that define radioactive waste: for example, all the wastes containing ≥ 1 Bq/g by source Ra226 have to be considered as radioactive, whereas only radioactive wastes containing ≥ 10 Bq/g by source Ra226 have to be disposed of in a repository equipped for the purpose, and definitively stored. All wastes with levels of radioactivity between 1 and 10 Bq/g (from Ra226) can be handled and disposed by any company that owns a license for the management of hazardous wastes. Management of other radioactive wastes requires a license issued ad hoc by the NRPA.
The largest quantity of wastes containing naturally occurring radioactive isotopes (NORM) and with activity levels from Ra226 ≥ 10 Bq/g comes from the Oil&Gas industry. Therefore, all this material, properly treated, shall flow into a final repository.
Dates back to 1981 the discovery of levels of radioactivity “out of the norm” (i.e. average values above those expected for the natural background) in deposits (scale, sands and sludge) of by-products from North Sea oil and natural gas production. The specific activity of the solid dry material varies from the natural radioactive background level to several hundreds of Bq/g (from Ra226 and Ra228) . For workers involved in the different operations of handling and treatment/cleaning of equipment or contaminated waste the doses are usually very low (maximum estimated value: 0.2 mSv/year) – well below the standard limit of dose for exposed workers (20 mSv/year). The main problem is the disposal of this type of radioactive waste, considering the amount of surfaces to be cleaned, and harvesting and treating of waste (i.e. moderate levels of radioactivity, but large quantities to be disposed of).
Since 2008, Norway features a storage place ready to receive the large amounts of NORM wastes coming from the Oil&Gas industry, both domestic and European (for some detail see Fig. 5 and 6, and their captions). The repository is located in Sløvågen, Gulen, Sogn og Fjordane county, at Stangeneset industrial site, and currently is able to contain little more than 7000 tons of NORM wastes, suitably and definitively stored. However, according to most estimates, the amount of wastes will increase significantly in the future due to the decommissioning of offshore facilities.
That’s why while using Gulen’s repository a search for new locations is already going on. Similar problems affect the management of low radioactivity NORM wastes as well.
This is the case of Langøya Island , managed by NOAH AS (Norsk Avfallshåndtering AS – literally Norwegian Corporation for waste treatment), which is going toward an environmental restoration.
As can be easily noticed from pictures in Fig. 7, the island doesn’t offer an amazing sight at present, due to the fact that after being used as a quarry for decades (chalk extraction), since 1985 Langøya has been converted to special waste disposal. Most part of it are NORM ashes , from manufactury and urban solid waste combustion from Norway, Sweden and Denmark. The island also hosts some facilities devoted to treatment of the waste destined to disposal. One of the core duties of NOAH on the island is in fact to transform the incoming wastes in materials that are environmentally safe for disposal in the quarry. And as far as we understood , part of the waste is treated to be recycled as construction material.
NOAH experts calculated that, given the actual filling rate and the likely future increase, the island will be unusable in 10 years, and they put all the future expectations on the old chalk mines at Brevik (Dalen mines).
Down there a new disposal for high radioactive NORM wastes could see the light.
However, as reported by media, local population doesn’t like the idea so far. Still a lot of work ahead, and few time, to win the resistance of the public opinion with the right argumentations, that means with feasible benefits for the local communities.
 Institute for Energy Technology. Source:StrålevernRapport– Joint Convention on the Safety of Spent Fuel Management and on the Safety of Radioactive Waste Management.
 Besides those already mentioned, other industries producing NORM wastes are: coal burning, metallurgy, Rare Earths manufactory, fertilizers production, construction materials production, recycle. Thus the acronym TENORM (Technologically Enhanced NORM) is often used to identify those material whose radioactivity is augmented due to higher concentration of radionuclides resulting from transformation and industrial processing. NORM wastes result from non-industrial sectors too: Radon exposition in residential sector, commercial flights, etc. For more details, please have a look at what reported by WNA here.
 Concerning oil extraction it seems the peak was reached in Norway in 2001. Natural gas has still good perspectives. More details here and here.
 Based on samples from solid deposits and scales (see Fig. 4), collected from Norwegian offshore platforms, the average value of radioactivity concentration (from Ra226 and Ra228) is close to 25 Bq/g: results range from few Bq/g to few hundreds of Bq/g – to be noticed that the upper limit of the range is still significantly smaller of values reported in other studies concerning offshore platforms in the USA (e.g. 3700 Bq/g) and onshore extraction in Syria (e.g. 1000 Bq/g).
In the following few notes about the most cited radionuclides in this article:
Ra226 has half-life of 1600 years, it’s an alpha emitter from the U238 series (see Fig. 2);
Ra228 has half-life of 5.75 years, it’s a beta emitter from the Th232 series;
a generic measure of the radioactivity of a certain material doesn’t give any information about the radio-toxicity of the material itself (e.g. a barium sulfate scale can present 23 MBq/t as a sum of the specific activity of all the radionuclides that it contains). However when the activity of the Radio is monitored a precautionary/conservative approach is assumed, being Radio’s radionuclides the most active in nature (shortest half-life), the most diffused and with the most dangerous emissions in case of food chain contamination and/or prolonged exposure.
 Island located in the Re Municipality, Oslofjord, Norway – not to be confused with the homonym island located in the Tjøme Municipality, and neither with the other homonym but bigger island in the Vesterålen archipelago.
 Fly ash, is a by-product of coal combustion in thermoelectric power plants and falls in the NORM category, but with radioactivity levels from Ra226 lower than 10 Bq/g.
 Most of the information we found on this topic were in Norwegian.
Weers A.W. et al., “Current Practice of Dealing with Natural Radioactivity from Oil and Gas Production in EU Member States”. Report EUR 17621, Directorate-General Environment, Nuclear Safety and Civil Protection, European Commission, Luxembourg (1997).
Strand T. et al., “Deposits of Naturally Occurring Radioactivity in the Production of Oil and Natural Gas”. Norwegian Radiation Protection Authority Report 1997:1, p. 136 (1997).
MacArthur A., “Development and Operation of a NORM Processing and Disposal Facility for the U.S. Oil and Gas Industry”. 19th Annual National Conference on Radiation Control, May 18-21, 1987, Boise, Idaho, USA. Conference on Radiation Control Program Directors, CRCPD Publ. 88-2, Frankfort, KY, USA, 1988.
Al-Masri M.S., Suman H., “NORM Waste Management in the Oil and Gas Industry: the Syrian Experience”. J. Radioanalytical and Nuclear Chemistry 256(1): 159-162, 2003.
Segnaliamo che mercoledì 20 gennaio, alle ore 17:00, avrà luogo a Trieste una conferenza dal titolo:
“Le scorie dell’energia. Come chiudere il ciclo di una fonte?” Luogo: aula magna del Dipartimento di Scienze Giuridiche, del Linguaggio, dell’Interpretazione e della Traduzione, in via Filzi 14 a Trieste. Relatore: dott. Pierluigi Totaro (Comitato Nucleare e Ragione).
L’evento fa parte di un ciclo di conferenze intitolato “Energia, società e ambiente. Tra passato, presente e futuro“, promosso dai Dipartimenti di Studi Umanistici e di Fisica dell’Università di Trieste, da Sissa Medialab, Elettra-Sincrotrone, Ceric-Eric, Comitato Nucleare e Ragione, Nuclear Italy Research Group.
Poche ore prima dello scoccare della mezzanotte del 31 dicembre 2015, l’ultimo Magnox rimasto operativo è stato spento definitivamente, e con questo si è conclusa una storia che risale al 1956.
60 anni fa, il primo reattore del tipo Magnox fu inaugurato dalla regina Elisabetta II a Calder Hall, in Cumbria presso il complesso di Sellafield – doveva essere il primo di otto. Ora la regina è sempre la stessa, ma non ci sono più Magnox attivi né in Inghilterra né nel resto del Mondo.
“Magnox” sta per “magnesio non-ossidante”, un termine che descrive il rivestimento in lega di magnesio (incamiciatura delle barre di combustibile) utilizzato in questo tipo di reattori moderati a grafite e con anidride carbonica come fluido termovettore.
Il combustibile era uranio naturale in forma metallica – dettaglio non secondario.
Nel corso degli anni sono state costruite unità assai più grandi, ottimizzate per il servizio commerciale, abbandonando man mano l’opzione iniziale della doppia produzione di elettricità per usi civili e plutonio per usi militari. Anche la centrale di Latina realizzata in Italia nella prima metà degli anni ’60, in esercizio dal 1963 al 1987, era del tipo Magnox.
Ora vanno forte gli AGR (Advanced Gas-cooled Reactor), e ci sono interessanti prospettive per il futuro – ne riparleremo senz’altro. Ma quella dei Magnox è stata tra alti e bassi una lunga storia di successo. Una storia che nel Regno Unito è stata scritta in questi siti:
• Berkeley, Gloucestershire
• Bradwell, Essex
• Chapelcross, Dumfriesshire
• Dungeness A, Kent
• Harwell, Oxfordshire
• Hinkley Point A, Somerset
• Hunterston A, Ayrshire
• Oldbury, Gloucestershire
• Sizewell A, Suffolk
• Trawsfynydd, North Wales
• Winfrith, Dorset
• Wylfa, Anglesey, North Wales
La centrale di Wylfa, Galles, che univa 2 reattori Magnox da 490 MWe cadauno e 4 generatori a turbina, è stata l’ultima ad operare – ed è mancato poco che non durasse così a lungo. In origine si prevedeva infatti di chiudere l’impianto nel 2010, ma è stato fatto uno sforzo incredibile per trasferire il combustibile in parte esausto da un reattore all’altro, permettendo al reattore dell’unità A1 rimasto funzionante di operare fino all’altro giorno. L’unità A2 ha chiuso i battenti nel 2012.
La Magnox Ltd. ha reso disponibile un breve video che mostra lo storico shutdown della sua ultima unità. Buona visione!