Tritium concentration in different European surface waters

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Content: Tritium Concentration in Different European surface waters
Carmen Varlam National Institute for Cryogenics and Isotopic Technologies - ICIT Uzinei Street no.4, PO Box 7, RO 240050, Rm. Valcea, Romania [email protected] Ioan Stefanescu, Amalia Soare, Ionut Faurescu [email protected], [email protected], [email protected]
ABSTRACT Tritium level and its evolution in several surface waters from France, Germany, Suisse, United Kingdom, and Belgium are presented in this work. The values of tritium concentration are studied comparatively for two periods 1993-1994 and 2007-2008, these values being extracted from different monitoring reports of environmental radioactivity. The Danube River Basin is studied in this paper also. Applying "Global Network of Isotope in Precipitation" model, International Atomic Energy Agency developed the "Global Network of Isotopes in Rivers" one of the monitored isotopes being tritium. The recorded values over 39 years in Vienna location for Danube water show a decrease in the last years despite the numerous Nuclear Power plants settled on its basin. Most cases of environmental 3H contamination are harmless, from the standpoint of radiation protection. The tritium average concentration found in the surface water is far below the permissible value of 100 Bq/l tritium concentration for drinking water. However, the contamination does cause an increase in environmental H-3 concentrations, which sometimes are several orders of magnitude more than usually environmental values.
1
INTRODUCTION
Tritium is produced both by neutron processes, interaction of cosmic rays in the atmosphere, and by industrial activities. Currently, almost 80% to 90% of tritium in the environment was released in the early `60s due to nuclear tests conducted in many countries in that period. We must not forget the use of tritium in consumer goods such as watches, thermostat dials or out port lights of airplanes. Both artificial and natural sources have been contributing to the environmental tritium level. Taking into account the high neutron flux in the core of nuclear reactors, it is not a surprise the tritium production for any type of reactor by activating nitrogen, hydrogen, helium or boron [1]. Tritium can be produced in the following components: moderator and cooling circuit if water is used, moderator and cooling circuit if heavy water is used, cooling circuit if helium is used, Boron rods used by the vast majority of reactors, moderator if graphite is used due to lithium impurities, and fuel rods due to the lithium and boron impurities. Contamination pathways of environment are either through gaseous emissions into the atmosphere or through liquid effluents discharged by a nuclear plant. Although these are local sources, the level of tritium in emissions can be quite high, resulting in high tritium concentration in ground water, surface water or Plant Cellulose. For example, a LWR-BWR- 1204.1
1204.2
type reactor, 1000 MW, releases into the environment around 1010 Bq/year (from 20 to 30 Ci/year) [1], in the range of the smallest hydrogen bomb detonated during the `60s [2]. If tritium is an unavoidable product resulted from the operation of a nuclear power plant, the quantity and ratio between fractions released in air and as liquid, vary considerably from one reactor type to another. The paper presents tritium level evolution in different European surface water, tritium concentration being extracted from scientific publications and radioactivity monitoring reports from France, Suisse, United Kingdom, Belgium, and Germany.
2
TRITIUM LEVEL IN EUROPEAN SURFACE WATERS
In Europe, France produces most of its electricity from nuclear activities. French nuclear power plants are made of 58 PWR-type nuclear reactors (Pressurized Water Reactor), all located near water courses or shores. The French Institution responsible with monitoring surface and underground waters for that period was "L'Office de Protection contre les Rayonnements Ionisants" (OPRI). The activity report for year 1994 issued by this institution [3] indicates for Loire River over 70 Bq/l in certain times of the year and in some points, figure 1.
Figure 1: Tritium level evolution in surface waters from France (modify after [5]) The same for Seine where the flow is low in certain periods of the year; downstream nuclear power plant from Nogent there were frequently recorded values over 20 Bq/l. In the case of Rhone River, which is regulated and has a high flow, values did not exceed 30 Bq/l even though there is the highest density of nuclear power plants from Europe on its course. Generally, one can notice a large variation of tritium from month to month because the discharge of liquid effluents is not regular. A special case is Doubs River which frequently has values of 80 Bq/l in Goumois locality. This river comes from France passes through Switzerland before returning to France. In Switzerland, when passing through the Chaux de
1204.3 Fonds, the place of Swiss watches industry, its content of tritium increases to values measured in France. For the Reprocessing Plant and the Deposit of Radioactive Waste L'ANDRA from La Hague the annual values in the nearby streams range from 38 Bq/l (Moulinets) to 460 Bq/l (St Helene) for year 1994 [4]. In the report "Bilan de L'йtat Radiologique et de L'environment Francais en 2007" [5], it was indicated a decrease in activity reported for Loire basin with an average value of 14 Bq/l (maximum of 52 Bq/l downstream Saint-Laurent des Eaux nuclear power plant, during liquid effluents discharge). Rhone does not exceed 16 Bq/l tritium concentration in water during liquid effluents discharge from the five nuclear power plants located on its course. Values between 49 and 54 Bq/l during discharges from Nogent nuclear plant were recorded on Seine. On French coast, in the nuclear power plant area close to liquid effluents discharge pipes there were frequently recorded values between 22 Bq/l and 57 Bq/l. The most dramatic decrease was recorded on Doubs River with values below 10 Bq/l. Overall, comparing tritium concentration values for French surface waters between 1994 and 2007 it can be noticed a moderate decrease of discharges into the environment but with the same local contamination caused by the nuclear facilities. In Switzerland, L'Office Fйdйral de la Santй Publique Suisse publish an Annual Report [6]. Measurements performed in surface waters, drinking water and underground waters indicate tritium average activities of below 7.7 Bq/l. The highest tritium concentration measured in 1993 was between 40 and 150 Bq/l for Doubs River, in St. Ursane location. These values are explained on one hand by the discharges from Chaux de Fonds and on the other hand by the very low flow of this river (around 30 m3/s). Rhone values do not exceed 5 Bq/l and tritium concentration in Aar, upstream four nuclear facilities located on its course, does not show values higher than 2 Bq/l. There were tritium values over 7 Bq/l in 1993 downstream nuclear facilities, on the same Aar River. Figure 2: Tritium level evolution in surface waters from Switzerland (modify after [7]) In the year 2008, the results of radioactivity measurements in environment for Switzerland [7] do not represent a health hazard, figure 2. In case of surface waters, values are constantly below 3 Bq/l both for Rhone and for Aar rivers. Also, the activity reported for Doubs River at St-Ursanne has decreased, with values below 10 Bq/l over the past 5 years. This is explained by a decrease in the use of tritium in Swiss watch manufacturing industry.
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The same report from 2008 presents values of tritium concentration in water from treatment plants for large communities but where there are also incineration plants of tritiated waste, like Zurich, Bale, Berne, Lausanne and Chaux de Fonds. Reported tritium average values range from 6.7 Bq/l (STEP Bale) to 615 Bq/l (Bale incineration plant with a maximum concentration of 12880 Bq/l in washing water). All values reported for 2008 have decreased significantly even for Bale incineration plant which in 2006 had a maximum of around 860000 Bq/l tritium concentration in washing water.
In the United Kingdom in 1993, the report on environmental monitoring of radioactive substances program was managed and published by Her Majesty's Inspectorate of Pollution [8] but for the year 2007 this report was jointly made by several agencies [9]: Environment Agency, Food Standards Agency, Northern Ireland Protection Agency and Scottish Environment Protection Agency. The vast majority of nuclear facilities in this country are located on the coast. They are either nuclear power plants or military units or Research Institutes. Most of liquid discharges are released into the marine environment, except for laboratories located on Thames (Harwell-Oxford). However, there were also performed measurements of surface waters near more important nuclear facilities. Table 1 shows a comparison between tritium values found in 1993 [3] and values found in 2007 [9] for several locations with nuclear power plant.
Table 1: Tritium concentration in water near some nuclear facilities in the United Kingdom
Nuclear facility ­ sampling Tritium concentration in Tritium concentration in
location
1993 (Bq/l)
2007 (Bq/l)
Selafield reprocessing plant
Calder river upstream
4 - 21
< 6.4
Calder downstream, Ehen,
3-6
<5.3
Mite, Irt, Esk rivers
Ehen river 11
Ehen Spit beach 710
Sizewell NPP
Nature Reserve
9
<4.0
The Meare
4.7
<4.5
Leisure Park
4.3
<4.5
Bradwell NPP
Drinking water
4.2
<4.0
Dungeness NPP
pumping station
3.2
Pumping station 1 10
Pumping station 2 <4.0
Hinkley Point NPP
Durleight Reservoir
3.9
<4.5
Ashfort Reservoir
4.1
<4.0
Berkeley NPP
Gloucester and Sharpness
3.9
<4.0
Canal
Oldbury NPP
Drinking water
4.2
<4.5
Heysham NPP
Drinking water in Lancaster 8.2-10.9
<4.0
Seawater from harbour
-
12 Bq/l
Trawsfynydd NPP
Drinking water
5.2
<4.0
Trawsfynydd Lake
3.9 ­ 5.0
<4.0
1204.5
Harwell Laboratories
Lydebank Brook
10.4 -59.5
<4.5
Thames upstream
4.1 ­ 7.0
<4.5
Thames downstream
5.8 ­ 77.4
<4.0
Day's Lock
3.8 ­ 19.8
<4.0
It clearly noticed a decrease in level of tritium released into the environment either due
to decommissioning of some nuclear objectives (Imperial College Reactor Centre, Ascot, and
Berkshire) or dilution required by operating licenses.
In Belgium, during 1993-1994, the Institute National des Radioйlйments published values of tritium concentration in four different points [3]. For locations Hastiere (downstream Chooz nuclear power plant in France) and Huy (upstream Tihange nuclear power plant) measured tritium values per week ranged from 4 and 13.3 Bq/l. In Meuse River, tritium values were higher due to liquid discharges of Tihange nuclear power plant. Two locations were monitored: Ampsin downstream the plant and Monsin also downstream the plant, but at a greater distance, downstream Liege city. For the year 1993, there was recorded an average value of 18.8 Bq/l in Ampsin and 16.7 Bq/l in Mosin and for the year 1994 the average was 12.4 Bq/l in Ampsin and 11.5 Bq/l in Monsin. Comparing these values with those published by Agence Fйdйrale de Contrфle Nuclйaire for the year 2007 [10], a higher number of monitoring points are identified and tritium concentration values are higher than those from 1993-1994. In the basins of Meuse and Sambre Rivers (for Tihange NPP and IRE Fleurus) in locations Andenne and Huy, there were found values ranging from 10 to 28 Bq/l, in Ampsin from 11 to 51 Bq/l and in Monsin from 12 to 36 Bq/l. Nuclear activity of rivers Nete and Escuat basin, consists of the nuclear power plant from Doel, SCK-CEN Mol research institute and Belgoprocess, Belgonucleaire and FBFC International nuclear fuel plant from Mol and Dessel. Tritium values reported for the water from location Molse Nete (sampling point near discharges from Belgoprocess 2 from Mol-Dessel) range from 16 and 170 Bq/l with a peak in June 2007 of 740 Bq/l. Downstream this location, in Grote Nete, there were found values ranging from 5 to 33 Bq/l and in Escaut River, downstream Doel, values were between 6 and 18 Bq/l. As a conclusion for this country, even though the nuclear activity has increased, the environmental monitoring complies both with European directives and support of local industry.
In Germany during `90s, surface waters entering the country were monitored by several international committees, such as "International Commission for Rhine Protection against Pollution" or "International Commission for Moselle and Sarre Protection against Pollution". These committees used to collect samples both from Germany and from neighbouring countries. The results of physico-chemical analyses were centralised and published on an yearly-basis [11, 12]. In 2008, the report on monitoring of environment radioactivity in Germany was published by "Bundesministerium fьr Umwelt, Naturschultz and Reaktorsicherheit" (BMU). It centralized the results from more than 7 institutes and organisations across the country (Max Rubner Institute, Physikallsch-Technische Bundesanstalt, Bundesamt fьr Strahlenschutz, etc.). Regarding radioactivity measurements and in particular tritium measurements they were systematically performed in four measuring points on Moselle, one point on Sarre and three points on Rhin. All measurement points on Moser River are downstream Cattenom nuclear power plant. Tritium values for 1992 and 1993 were 11.6 Bq/l (Coblence for 1992) and below 34 Bq/l (Palzem in 1993). In case of Sarre River, the sampling point is located before its confluence with Moselle River and because on its course there is no nuclear facilties it is considered a reference location. The tritium value for Kinz location was below 15 Bq/l. Regarding the Rhine, the two nuclear locations Juelich and Muelheim-Kaerlich are between Lobith and Coblence. More nuclear
1204.6 plants are on its course, such as Philipsburg, Biblis and Karlsruhe. Published values were between 6.4 Bq/l (Lobith in 1992) and 7.2 Bq/l (Coblence in 1993). Radioactivity reports for Germany in 2006-2007 were performed by the Federal Superior Authority of Federal Ministry of Environment, Nature Conservations and Nuclear Safety [13]. There were reported average annual tritium values over the last 10 years in different surface waters. The highest values are in Mosel, at Koblenz, with average annual values of over 10 Bq/l and a maximum in 1998 of over 20 Bq/l. It is followed by Ems River with average annual values of aver 4 Bq/l and a maximum in 1989 of over 9 Bq/l. The lowest values were reported for river Wesser with an average below 4 Bq/l and a maximum not too much over 4 Bq/l. In the case of the Danube, average annual values are also 4 Bq/l with a maximum of 6 Bq/l in 1996. Danube River represents a special interest for Romania. It is the natural border with Bulgaria, and the only Romanian Nuclear Power Plant is located on its border, in the Lower Danube Basin. The Danube flows through eights countries and drains a total of eighteen, being the second largest river basin in Europe covering 801463 km2 [14]. Nuclear electricity has been, on a variable cost basis, cheaper than other options, and consequently used in preference to coal, oil and gas. Nuclear power generates between 10% and 45% of electricity in the Danube Space countries [15]. There can be found over 25 nuclear reactors. Using its experience gained by the successful program Global Network for Isotopes in Precipitations (GNIP), International Atomic Energy Agency has launched a monitoring program Global Network for Isotopes in Rivers (GNIR), aimed at regular analysis of the isotope composition of runoff in large rivers. One of the analyzed isotopes was tritium. The Vienna station has one of the longest data records, starting with '60. The recorded tritium values over 39 years in Vienna location for Danube decrease from 544.3 +/- 5 TU (mean of 1966) to 16.3 +/- 2.2 TU (mean of 2005). The nuclear activity developed along the Danube is present in the recorded values by the maximum values of 66.7 +/- 0.5 TU (December 2002), or 129 +/- 0.5 TU (July 2004), figure 3. 160 140 120 100 80 60 40 20 0 Ian-02Apr-02 Iul-02Oct-02Ian-03Apr-03 Iul-03Oct-03Ian-04Apr-04 Iul-04Oct-04Ian-05Apr-05 Iul-05Oct-05 sampling months Figure 3: Tritium level of Danube River for Vienna station during 2002-2005 (tritium data are from IAEA GNIR, available at http://www.univie.ac.at/cartography/project/wiser) On a regular basis, river water in most parts of Danube River Basin reflects the environmental tritium level of about 15 TU with precipitation as input, [16, and 17]. All river water values exceeding about 17 TU are believed to be the consequence of human activities. In most cases such contamination is of a short term character. Tritium releases from nuclear power plants can be used to study travel time and dispersion of contamination pulses in the
Tritium concentration [TU]
1204.7
Danube. This could be a basis for the development of emergency measures to deal with pollution accidents in the catchment area.
3
CONCLUSIONS
By 1998, there were no European standards for drinking water radioactivity; ALARA ("As Low as Reasonably Achievable") principle used to be applied and ICRP recommendations which for tritium recommended a level of 7800 Bq/l. Starting with November 1998, the European Commission issued the Directive 98/83/EC on quality of water intended for human consumption. Besides microbiological and chemical quality, the directive imposed two important values from the radioactivity point of view: tritium concentration of 100 Bq/l and annual dose of 0.1 mSv (calculated without tritium, K-40 and Rn-222 contribution). This important directive has a major impact on the operation of nuclear facilities, tritium concentration in surface water from the surrounding nuclear facilities decreasing to the natural level. Studying the reports on monitoring of environment radioactivity published by the vast majority of European countries, in most cases it can be noticed a significant decrease of tritium concentration in the environment for 2007 (e.g. France, Germany, Switzerland, and United Kingdom). The same situation can be found in the Danube River Basin, tritium level in Danube River water is continuously decreasing from 2025 TU in 1995 [18] to precipitation level, even if the nuclear facilities are in this area.
ACKNOWLEDGMENTS This paper was prepared in connection with work done under Black Sea Pilot Joint Call for Research Proposals, contract number BS7-049/P1/2011, and Cooperation Project with Slovenia, contract number 5039/07/06/2012. The authors wish to thank Stefan Terzer, IAEA ­ Isotopes Hydrology Section, for his valuable information.
REFERENCES [1] IAEA, International Atomic Energy Agency, Management of waste containing tritium and Carbon -14, Technical Reports Series no. 421, Vienne, 2004, pp. 28-32. [2] UNSCEAR, United Nation Scientific Committee on the Effect of Atomic Radiation, Report of United Nation Scientific Committee on the Effect of Atomic Radiation to General Assembly, annex B, Exposures from natural radiation sources, 2000, pp. 115. [3] OPRI, Office de Protection contre les Rayonnements Ionisants, Raport d'activite 1995, Le Vesinet, France, 1996. [4] V. Tort, C. Lefaure, G. Linden, J. Herbelet, ,,Le tritium dans le millieu aquatique et le risque associe", Radioprotection, vol.32, nr.4, 1997, pp. 501-519. [5] IRSN, Institut de Radioprotection et de la Suretй Nuclйaire, Bilan de l'йtat radiologique de environnement franзais en 2007, report DEI/SESURE no. 2008-48, http://www.irsn.fr/publication, 2008. [6] OFSP, Office Fйdйral de la Santй Publique, division de radioprotection, Radioactivitй de l'environnement et doses rayonnement en Suisse en 1993, Fribourg, Suisse, 1994.
1204.8 [7] OFSP, Office Fйdйral de la Santй Publique, Radioactivitй de l'environnement et doses rayonnement en Suisse en 2008, Fribourg, Suisse, 2009. [8] HMIP, Her Majesty's Inspectorate of Pollution, Monitoring Program, Radioactive Substances Report for 1993, United Kingdom, 1994. [9] Environment Agency, Food Standards Agency, Northern Ireland Environment Agency, Scotish Environment Protection Agency, Radioactivity in Food and Environment 2007, RIFE-13, http://www.food.gov.uk, 2008. [10] Agence Fйdйrale de Contrфle Nuclйaire, Surveillance radiologique de la Belgique, Raport de synthese 2007, http://www.fanc.fgow.be, 2008. [11] CIPMS, Commission Intйrnational pour la Protйction de la Mosselle et de la Sarre Contre la Polution, Qualitй des eaux de la Mosselle, de la Sarre et de leurs affluents, annee, 1993, Moulins-le Metz, France,1994. [12] CIPR, Commission Intйrnational pour la Protйction du Rhin (CIPR), Tableaux numйrique des analyses physico-chmiques des eaux du Rhin et des matiиres en suspension, annйe 1993, Coblence, Allemagne, 1995. [13] Bumderministerium fьr Umwelt, Naturschutz und Reaktosicherheit (BMU), Umweltradioaktitдt in der Bundesrepublik Deutschland 2006 und 2007, Bonn, 2008. [14] ICPDR, International Commission for Protection of Danube River, The Danube River Basin District Part A - Basin wide Overview, 2005, http://www.icpdr.org/ DANUBIS. [15] EC, European Commission DG: Region Policy, Danube Space Study ­ Regional and Territorial Aspects of Development in the Danube Countries with Respect to Impact on the European Union, ANr. A 22404.00, Vienne, 2000 [16] C. Varlam, I. Stefanescu, I. Vagner, I. Faurescu, D. Faurescu, "Tritium level along Romanian Danube River Sector", in Proceedings on Third European IRPA Congress, Helsinki, 2010. [17] D. Rank, W. Papesch, G. Heiss, R. Teisch, Environmental isotopes ratio of river water in the Danube River Basin, In: IAEA ­ TECDOC ­ 1673, Monitoring Isotopes in Rivers: Creation of the Global Network of Isotopes in Rivers, pp. 13-41, 2012. [18] D. Rank, E. Ozsoy, I. Salihoglu, Oxygen-18, deuterium and tritium in the Black Sea and the Sea of Marmara. Journal of Environmental Radioactivity, no. 47, pp. 77-87.

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