Environmental Radioactivity Surveillance Programmes at ENRESA s Facilities

Transcription

1 Environmental Radioactivity Surveillance Programmes at ENRESA s Facilities M.T. Ortiz*, J.A. Garcia*; M.L. Sánchez-Mayoral**, E. Blázquez** (*)ENRESA, Emilio Vargas, 7 Madrid SPAIN (**) Iberdrola Ingeniería y Consultoría S.A.U., Avda. de Burgos 8 B Madrid SPAIN ebar@iberinco.com Abstract. The Environmental Radioactivity Surveillance Programme (ERSP) includes a set formed by the network of monitoring and the procedures of sampling, analysis and measurement, directed to determine the possible increase the radiation levels and the presence of radionuclides in the environment because of the existence in the surroundings of nuclear facilities, with the main object to evaluate the radiological impact derived from the operation of the facility. Once a year, ENRESA (Spanish National Radioactive Waste Management Company) develops the reports related to the Environmental Radioactivity Surveillance Programmes for its three different facilities: El Cabril a near surface disposal facility for Low and Intermediate Level Waste (LILW), Andújar Uranium Mill (AUM) a decommissioned processing site and Vandellós I a decommissioned nuclear power plant. The main differences between these facilities, that define their surveillance programmes, are the source term that defines the analyses to carry out of the samples gathered according to the established exposure pathways based on the site. Since 1986 ENRESA has carried out these programmes for El Cabril and AUM site and since 1998 for Vandellós I. During this time, a wide experience had been acquired to illustrate in this paper a brief description of the facilities in order to compare the different ways to develop their annual reports according to their Environmental Radioactivity Surveillance Programmes. 1. Introduction The population has always been exposed to natural radiation sources. For this reason, doses change from one site to another. The natural activity is detected in several environmental samples: rivers, soils, and vegetation... Consequently, before the operation at any facility is carried out a study of measuring of activity in the involved environmental samples, in order to determine any change promoted by nuclear facilities. The main objective of an ERSP is to provide information and data for the assessment of actual or potential doses to population, to ensure the protection of human health and the environment nowadays and in the future, against adverse effects from the management at nuclear facilities. Therefore, it could be demonstrated compliance with the regulatory requirements and the adequacy of the operation at the facility. In the Spanish legislation the Royal Decree 1836/1999 [1], about nuclear and radioactive facilities, establishes that every nuclear facility has to deliver an annual report, with the ERSP results, to the Regulatory Authorities (Nuclear Safety Council and the Ministry of Economy). The Nuclear Safety Council has edited a Safety Guide [2] where is described the way to carry it out. The purpose of this paper is make a brief description of the facilities in order to compare the different ways to develop their annual reports according to their specific ERSP. 2. Facilities description ENRESA has three different facilities that are showed in figure 1 and described below: Andújar Uranium Mill (AUM): Decommissioned Processing Site located in the western part of the province of Jaén next to the limit with the province of Córdoba. El Cabril: Near Surface Disposal Facility for Low and Intermediate Level Waste (LILW) located in the Northeast of the province of Córdoba, at a distance of about 130 km from the capital. Vandellós I: Decommissioned Nuclear Power Plant located in the municipal term of Vandellós I l`hospitalet de l Infant (Tarragona). 1

2 FIG. 1: Situation of ENRESA's Facilities The ERSP is based on sampling and measuring campaigns of the current radioactivity in the different transfer vectors in the environment: air; rain, river, sea, drink water; river and marine sediments; river and marine fauna and flora; food chain; etc. The frequency of sampling and measuring was defined with the aim to obtain the best representative information about the radiological situation of the site, taking into account the material and technical possibilities at the facilities. It is stablished a quality control for the analysis and measuments process. For each facility, a laboratory accredited by the Regualtory Authorities carries on analysis and measurements of a percentage of the samples taken, in order to verify the results obtained by the conventional laboratoty. Every facility has annually associated a sampling and measurement time table where is specified the days when all the samples will be pick up and the analysed and measures that will be carry out for each sample and both laboratories Andújar Uranium Mill (AUM) Nowadays, after the period of dismantling and restoration activities the AUM site is in the period of surveillance, this would have a minimum duration until The activity inventory authorised for the site is 200 TBq referred to the isotopes of the U-238 chain. ENRESA develops every year an annual report related to the ERSP [3] to ensure that the facility will not produce any radiological impact on the environment. As the site has already been restored, the exposure pathways are air and water Air Pathway This monitoring is useful to detect the influence of the radon on the surrounding environment because of airborne effluents. Now, one sample is taken every year. 2

3 Water Pathway This monitoring was established to control the radiological quality of the water and detect potential leaching from the restored facility. The monitoring includes the measurements of physical and chemical parameters on the same samples, as for example: temperature, water level, ph, Eh, chloride, chemical oxygen demand, copper, zinc, phosphorus, specific conductance, etc. There are two different samples: Surface Water There are three sampling points, one of them is an upstream control point. Sampling is performed quarterly and the samples are analyzed to measure: gross alpha activity, gross beta activity, gross beta without 40 K, total uranium, 226 Ra, 230 Th, 210 Pb, alfa uranium spectrometry Ground Water The samples are collected in wells (9) and boreholes (14) located in the representative points on the hydrological streamlines between the facility and the outflows. One of the wells is situated strategically as a control point. The sampling frequency and the types of analyses performed are the same ones as for the surface water samples El Cabril The facility consist basically of a LILW disposal facility which encloses a conditioning building, a Quality Verification Laboratory, other auxiliary installations and storage structures, made up of aligned cells. It is also included an incinerator for the biological and organic waste treatment. The activity inventory authorized for the end of the operating life is in the order of TBq of betagamma emitters, and 27 TBq of alpha emitters. To ensure that El Cabril disposal facility will not have any radiological impact on the environment, ENRESA develops annually an ERSP [4] involving samplings and measurements of radioactivity in the air, water, plants and other living beings in the environment. The limit values are indicated in the current regulations. The implemented monitoring and surveillance programme includes the monitoring of discharges. All effluents are controlled by continuous sampling and measuring of gross alpha and beta activity in gaseous effluents and by chemical and radiological parameters in liquid effluents before any discharge into rivers or streams Air Pathway These monitoring is carry out to detect the influence on the surrounding environment as a result of airborne effluents becoming from the incinerator and other installations as the LILW conditioning building or the Quality Verification Laboratory. There are seven points distributed around the area. The samples are collected by an electric air sampler with a pump capable of sampling up to 1.5 m 3 /min, that allows to get samples in a continuous manner. The filter is replaced weekly and analysed to measure gross beta activity and a composite sample is measured quarterly to determine gamma emitters (spectrometry) and 90 Sr (radiochemical analysis). At these seven points, samples are collected for the measurements of 3 H and 14 C on a quarterly composite sample. The 3 H samples are collected by adsorption on silica gel and 14 C by bubbling through baric hydroxide. 3

4 Water Pathway Surface Water To provide information about the potential presence of radionuclides derived from the waste as liquid effluent the monitoring programme includes 6 points. One of those is an upstream control point and the others are at permanent water impoundment and at surface water passing through the site, or off site, that may be subjected to direct surface drainage from potentially contaminated areas or form the discharge of liquid effluents. Sampling is performed quarterly and the analyses are the following: gross beta activity, gross beta without 40K, gamma emitters, 90Sr, 3H and 14C; 129I and 99Tc are also measured on 10% of the samples. The monitoring includes measurement of physical and chemical parameters on the same samples, as for example: temperature, water level, ph, Eh, chloride, chemical oxygen demand, copper, zinc, phosphorus, specific conductance, etc Ground Water To control chemical and radiological quality of water and determine potential leaching, from the disposal, there are 18 sampling points, located in wells around the disposal area, and a borehole located down gradient from the disposal as a control point. The sampling frequency and the types of analyses performed are the same as for the surface water samples Foods, Game and Fishing Food samples are representative of the local production: lamb from the nearest farm, honey from nearby beehives and as a control point they are collected as well from a remote location. Samples are pick up annually and analysed to measure gamma emitters. In the case of lamb it is also determined 90 Sr in bones. In addition, samples of fish and game are collected annually to determine gamma emitters in the edible parts and 90 Sr in the bones Indicator Organism The collected species of vegetation are the dominants in the area, they are collected as well at off-site locations representing both background conditions and potentially impacted areas. There are nine sampling points for vegetation at the same location where air is sampled. One of those is used as a control point because it is in a remote location. Every year is taken one sample in each point and analysed to measure gamma emitters, 90 Sr, 3 H and 14 C Soils and Sediments Any accumulation of radioactive material, released from the facility may appear in soils and sediments samples, therefore soil samples would reflect airborne transport of radionuclides and sediments samples are associated with liquid effluents. Soils samples are pick up annually at the same locations as vegetation and air samples. On each sample are measured gamma emitters and 90 Sr. Sediments samples are carried out in the same locations where surface water is sampled, but its sampling frequency is annual. Gamma emitters and gross beta activity is measured on each sample. 4

5 Direct Gamma Radiation The control of direct gamma radiation is associated with air pathways, radioactive waste transport and temporary storage in the old facilities. The measurements of external gamma radiation are carried out at nineteen points along the site boundary, ten points where air, surface water and vegetation are sampled and sixteen additional points around the temporary disposal buildings. The measurement frequency is quarterly Vandellós I At the present time, the facility is at the phase 2 of the Level 2 of the Decommissioning and Dismantling Project and it has a doses constrain of 100 µsv/y (80 µsv/y for the airborne dust and 20 µsv/y for the rest). To guarantee that no radiological impact from the facility is taking place on the environment, ENRESA develops annually an ERSP [5] involving samplings and measurements of radioactivity in the air, water, seaweeds and other living beings in the environment. Because of the proximity of Vandellós II to Vandellós I they share some sampling points. The limit values are indicated in the current regulations Air Pathway This monitoring it is carries out to detect the influence on the surrounding environment as a result of airborne effluents becoming from the operation of dismantling at the facility. There are six sampling points around the area, four of them are shared with Vandellós II. The samples are collected in the same manner than at El Cabril and the analysed carried out are the same as well, except for 3 H and 14 C that has a different sampling frecuency. 3 H samples, from the atmosferic water steam, are collected during a month every six months and the analysis frecuency is every six months as well. Atmosferic CO 2 sampling is continuous during one month a year at each sampling point, so the analysis frequency is annual for the accumalted samples of each point Water Pathway Rain Water The contaminated rain water pathway is through the air for that reason the isotopes involved are the same ones than in the air pathway. The monitoring programme includes 4 points, one of those is a control point. Sampling frequency is performed monthly and the analysis frequency is every two months. The analyses that are carry out from the samples are the following: gamma emitters, 90 Sr, and 3 H Sea Water Taking into account that liquid effluents go to the sea and there is no supply point of drinkable water, that could be influenced by these effluents, there is no points for their control but the surface water is been monitoring by sea water. 5

6 To control the radiological quality of the water there are 6 sampling points, one of them as a control point. The sampling and analysis frequency is monthly and the types of analyses performed are gross beta activity, gross beta without 40 K, gamma emitters and 3 H. It is included in the programme the deep sea water samples, which frequency sampling is every six months and the analysis that are performed are gamma emitters, 241 Am, 238 Pu and 90 Sr Foods and Fishing Samples of foods are representative of the local production considering the vegetables consumption per year for the different population groups, the areas of their production and the potencial gaseous effluentes. There are three sampling points, one of them shared with Vandellós II. The samples are almond, hazelnut, olive and carob bean. The sampling frequency is annual. Because of the liquid effluents, it has been considered the ingestion of fish, mollus and shellfish, so they are taken into account as samples to control every three months. The analysis carried out are: gamma emitters, 241 Am, 238 Pu and 90 Sr Indicator Organism The collected specie of seaweed is the most representative of the area. It is collected in seven different sampling points once a year. The performed analyses are gamma emitters, 241 Am, 238 Pu and 90 Sr Soils and Sediments Any accumulation of radioactive material released from the facility may appear in soil and sediments samples, therefore soil samples would reflect airborne transport of radionuclides and sediments samples are associated with liquid effluents. Soil samples are pick up annually at seven locations, one of those as a control point. On each sample are measured gamma emitters and 90 Sr with an annual frequency of analysis as well. Sediments from the shore are sampled in five locations, one as a control point. The sampling and analysis frequency is annual. The analyses carried out are gamma emitters, 241 Am, 238 Pu and 90 Sr. Sediments from the sea sampled twice a year, every six months in seven different sampling points. The analyses performed are gamma emitters, 241 Am, 238 Pu and 90 Sr and they have the same frequency than the sampling Direct Gamma Radiation The control of direct gamma radiation is associated with the air pathways. The measurements of external gamma radiation are carried out at eleven sampling points, four of them are shared with Vandellós I NPP, and one of these four as a control point. The sampling frequency is quarterly. 3. Analysis - Comparation In figure 2 is showed a schematic summary of the different exposure pathways, samples and analysis in the three facilities. As it could be observed, there are specific samples and analysis depending on the type of the facility (uranium mill, disposal facility or decommissioned nuclear power plant) and the site where they are located. 6

7 EPOSURE PATHWAY SAMPLES EL CABRIL VANDELLÓS I AUM GB BR Sr-90 GB BR Sr-90 Am-241 Ra-226 Th-230 DR H-3 C-14 I-129 Tc-99 GS DR H-3 C-14 Pu-238 GS GA GB BR TU Pb-210 AUS Rn-222 GAMMA RADIATION LEVEL QUARTERLY DOSIMETRY PARTICLES AIR CARBON TRITIUM RAIN WATER SEA WATER WATER DEEP SEA WATER SURFACE WATER GROUNDWATER HONEY LAMB CAROB BEAN FOODS ALMOND HAZELNUT OLIVES GAME FISHING INDICATOR ORGANISIM VEGETATION SEAWEED BORDER SEDIMENTS SEDIMENTS & SOIL BOTTOM SEDIMENTS SOIL DR: Dose Rate; GB:Gross Beta; BR:Gross Beta without K-40; GS: Gamma Spectromtry; GA: Gross Alfa; TU:Total Uranium; AUS: Alfa Uranium Spectrometry FIG. 2: Summary diagramm 4. Conclusions In this paper has been demonstrated that an ERSP could be quite diferent from one facility to another. As it could be observed in figure 3, the main differences are the source term that defines the analyses to carry out of the samples gathered according to the established exposure pathways based on the site. And all this information defines their Environmental Radioactivity Surveillance Programmes. facility site source term exposure pathways samples analysis ERSP FIG. 3: Conclusion 5. References [1] Real Decreto 1836/1999, de 3 de diciembre, por el que se aprueba el Reglamento sobre Instalaciones Nucleares y Radiactivas. [2] GS-4.1 Diseño y Desarrollo del Programa de Vigilancia Radiológico Ambiental (1993). [3] Programa de Vigilancia Radiológico Ambiental de La Fábrica de Uranio de Andújar. [4] Programa de Vigilancia Radiológico Ambiental del Centro de Almacenamiento de El Cabril. [5] Programa de Vigilancia Radiológico Ambiental de Vandellós-I. 7