DEVELOPMENT OF AN ENVIRONMENTAL MONITORING PROGRAM FOR IRD INSTITUTO DE RADIOPROTEÇÃO E DOSIMETRIA, CNEN.

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1 2005 International Nuclear Atlantic Conference - INAC 2005 Santos, SP, Brazil, August 28 to September 2, 2005 ASSOCIAÇÃO BRASILEIRA DE ENERGIA NUCLEAR - ABEN ISBN: DEVELOPMENT OF AN ENVIRONMENTAL MONITORING PROGRAM FOR IRD INSTITUTO DE RADIOPROTEÇÃO E DOSIMETRIA, CNEN. Vicente P. Melo, Elder M. Souza, Elaine R. R. Rochedo, Ana Cristina M. Ferreira, Sueli S. Peres Instituto de Radioproteção e Dosimetria (IRD / CNEN - RJ) Av. Salvador Allende s/n. Recreio dos Bandeirantes Rio de Janeiro, RJ vicente@ird.gov.br elder@ird.gov.br elaine@ird.gov.br anacris@ird.gov.br ABSTRACT IRD is an institution that performs different activities including metrology, supporting activities for the licensing and control activities of CNEN, and teaching and research in radiation protection. It has several small laboratories for performing radioactivity analysis in different types of materials, such as environmental and other biological samples, in support to its inspection activities of nuclear installation in Brazil and industries that use radioactive material. It also has a laboratory to prepare metrological standards for radioactivity analysis and other laboratories to support its research and training activities. As already happened with other laboratories and industries in Brazil, IRD was built in a remote site with no formal urban infrastructure. After 25 years and the growth of Rio de Janeiro town to the west coast, IRD is nowadays located in the surrounding of other governmental laboratories and institutions, and residential areas. IRD is not a nuclear installation and does not use or manipulate nuclear material. It is not, then, expected that the activities developed at IRD may lead to any significant environmental radiological impact. In order to fulfill national requirements, an environmental monitoring program has been established. This paper describes the difficulties to design and to implement such a program in an institution operating for more than 25 years and presents the preliminary results for the first two years of its environmental monitoring program. 1. INTRODUCTION The IRD - Instituto de Radioproteção e Dosimetria is located in Recreio dos Bandeirantes, Rio de Janeiro County, in the area of Jacarepaguá wetlands. Local climate can be described as tropical, with a humid summer and a dry winter. The original vegetation of the area can be divided in two groups, the humid tropical forest in the mountains and low vegetation and swamps in the wetland area. The area is dominated by a system of lagoons with an approximated total area of 7.6 km2, composed by 4 Ponds. IRD, founded in 1972, has authorization for the use of an area of m2. It has about 320 employees that include personal highly specialized in the areas of radiological protection, radiation measurements, radioecology and radiobiology. Due to the implementation of environmental directives in the Country, all Laboratories operated by the National Nuclear Energy Commission -- CNEN were requested to present an Environmental Impact Study and to implement an Environmental Monitoring Program. IRD

2 is different from most other CNEN Laboratories in the Country as it has no nuclear installation nor produces radioisotopes. It is composed by several laboratories with main work of performing radiochemical and radiometric analysis of samples in support to inspection actions of CNEN. IRD also is recognized by The National Institute of Metrology - INMETRO as a reference laboratory in Brazil for the metrology of ionizing radiation and maintains a service on calibrating radiation measurement equipments and providing radionuclide standards for other laboratories. As a scientific institution, IRD maintains a postgraduation course on radiological protection, covering the areas of medical exposure, occupational, individual, public and environment exposures with some laboratories working in research and training activities In general, the laboratories generate small amount of wastes and usually of very low activities, below background levels. Solid wastes are analyzed and when radioactivity levels are above those considered exempted by the pertinent regulation, they are stored and periodically send to temporary waste repositories in other institutes that maintain such materials under control. Liquid wastes are in general small and of low activity. Main discharge of laboratories is comprised by the washing of laboratory glassware. Nevertheless, a new waste system has been constructed, separating sanity wastes from wastes generated in the laboratories, in order to perform analytical control on all laboratories liquid wastes. It was considered that there is no atmospheric release as the laboratories procedures aim on preserving the radioactive material for analysis and any loss on sample preparation methods must then be avoided. 2. PROGRAM DESIGN The work related to the environmental impact assessment of IRD started in 2000, with a survey on all laboratories in order to classify them according to the kind and amount of radioactive material manipulated. This survey was the base to build the Environmental Monitoring Program. It was also clear that although occupational exposures are to be kept under strict occupational control, the possibility of any significant release of radioactive material to the surrounding environment is completely unreliable, considering the kind and amount of radioactive material manipulated in the laboratories. The monitoring program was then designed to confirm such assumption, considering the following main objectives: to verify the conformity of the operation of the facilities of the Institute with the applicable national norms; to evaluate the environmental radiological impact that the Institute could be causing in the neighboring environment; to evaluate the need of remedial actions. Surveys on climatic and hydrological characteristics of the site were performed and data from old monitoring programs performed by IRD were recovered from a survey performed during period, and a Site Report was presented in 2002, including a first proposal for an Environmental Monitoring Program that started being implemented at that same year. The potential of effluents generation stand out in the regulatory activity, as laboratories perform analysis of samples collected for environmental and occupational radiological follow-up of the facilities controlled by CNEN; preparation of radioactive standard sources; laboratory assays (radiometric and radiochemical analysis) and research activities. The total radioactivity released by all IRD laboratories is estimated to not surpass 10 3 Bq month -1, and main laboratories included in the separate waste system are described in Table 1.

3 3. PROGRAM IMPLENTATION The monitored environmental compartments are air, soil, lagoon surface water and sediments, ground water and vegetation. Measurements of the radiation levels are also accomplished at IRD laboratory area contour. The implementation of the program took some effort as there was the need of building sampling stations, to dig wells for underground water sampling, contact other institutions in order to have access to sample the lagoon water and sediments and building the new laboratories waste system that is now ready and under testing. All these questions demanded a review on the program previously presented and the new proposal, together with the justification, is presented in Table 2. The location of sampling stations is presented on Figure 1. Laboratory Table 1 -- IRD Laboratories Work description Radiochemical Laboratory Sources storage and analytical balance room Reference material preparation room Laboratory for samples preparation and radiochemistry laboratories Laboratory of effluent analysis Laboratory of samples preparation Laboratory of mass spectrometry Laboratory of mineral analysis Laboratories of radioecology Laboratory of radiochemistry Laboratory of chemistry Decontamination room Physical processing laboratory Bio analysis Lab and Aerosol Lab Metrology Preparation and calibration of radioactive sources Preparation standard radionuclide solutions Preparation of standard radioactive sources Preparation of solutions and environmental reference material for PNI (National Intercomparison Program) Environmental Radiological Protection Preparation and analysis of samples from inspection activities in nuclear installations, analytical services and PNI Preparation of radioactive standards; preparation of effluent samples from inspection activities. Preparation of samples from inspection activities in nuclear installations, analytical services and PNI Preparation and analysis of samples for natural radionuclides, enriched U and 233 U Analytical support for research activities of the mining group Research and analytical support in radioecology studies Radiological Protection in Industry Determination of U, Th, Ra and Pb in samples from inspection activities (air filters, ores, process samples, and others) Safeguards Preparation and analysis of samples of nuclear materials Decontamination of lab material used in nuclear samples analysis Preparation of solid nuclear standards Individual Monitoring Bio analysis in vivo and in vitro; aerosol analysis from mining facilities.

4 The measurement of external dose rates with TLDs started with only two monitoring points, at N and S directions, where soil and vegetation samples are also collected. There is now a network of 11 measurement points, including 8 point surrounding the laboratories area but internal to IRD, at the main wind directions, and additional three internal points close to main visited areas of IRD by non-occupationally exposed persons, such as the auditorium and classrooms and at the main road that gives access to calibration laboratories. The type of vegetation selected to compose the monitoring program followed the kind of vegetation available at each sampling point. At location S, initially grass was selected. Due to problems of spontaneous fires in dry season, the grass is now keep short cut all around IRD and the type of vegetation sampled was changed to tree leaves. At location N leaves of banana trees were selected, as they are quite abundant there. For the sampling of groundwater, a well already existent at SW and thus upstream all the laboratories was included in the program. A new well, at location E was prepared to fit the environmental monitoring program need for a downstream sampling point. All samples are analyzed at the Service of Environmental Analysis and the TLDs are processed by the Service of External Dosimetry of IRD, under standard methods already established by the laboratories. The air sampling is performed continuously under the CTBT Laboratory, located at NE, and the results are provided to be included in the environmental monitoring program of IRD. However, environmental control will only be complete as designed when the system of laboratory sewer is ready to be included in the monitoring program. IRD has no direct contact with the lagoon. Presently only one point in the Jacarepaguá lagoon is being sampled. A second point started being collected but problems related to access to the lagoon impeded to keep that location and a new one is being tried. The original program and the new proposed program are shown in Table 2, together wit the justification for the proposed changes. Table 2 -- Original proposed program and modification proposed during the implementation Type Local frequency New local New frequency justification Air N, S 4 /year NE 2 /year Data provided by CTBT* station on continuous on-line basis Soil N e S 4 /year annual Soil is an accumulating matrix adequate to long term assessments Well water 4 /year SW, E 2 /year There are no releases that justify keeping a 4 times per year sampling. Vegetation N e S 4 /year 2 /year There are no releases that justify keeping a 4 times per year sampling. Surface 2 sites 4 /year 2 sites Annual Difficulties on accessing the water Sediment 2 sites 4 /year 2 sites Annual lagoon; no impact is expected; sediments are also adequate for long-term assessments TLD 8 4 /year 11 sites 4 /year Three locations internal to IRD were included. *CTBT-station work for the Comprehensive Test Ban Treaty at IRD

5 4. RESULTS The sampling locations inside IRD are shown in Figure 1. External gamma dose rates measured by the PMA are presented in Figure 2. Average gamma dose rate inside IRD is about 119 ± 22 ngy h -1. This value is consistent with those determined by Sachett [1] for Recreio dos Bandeirantes (106 ± 19 ngy h -1 ). Although the IRD value is a little higher, it must be considered that the survey on Recreio dos Bandeirantes included all the beach area, which corresponds to lower gamma dose rates. It can also be seen that landfill areas (e.g. N location) presents results higher than original local sandy areas (e.g. S location). The difference in soil composition between N and S location was confirmed by soil samples. The observed variability is however consistent with normal variability. TLD readings for SW location were higher than the other measured values and an investigation program was established to assess the reliability and relevance of these measurements. Due to the proximity of the neutron metrology storage room, neutron dosimeters were installed at SW location. Results obtained with neutron dosimeters have shown that the TLD measurements were affected by neutron sources and gamma dose rates at SW locations corrected to the neutron component in TLD readings was seen to also be at background levels. The additional neutron dose rate decays rapidly with distance and contributes with a dose not higher than 1 µsv per month close to the measurement site, located about 10m from the building and more than 100m from the external fence. Average gamma dose rate at SW location was than estimated to be about 133 ngy h -1. Soil samples taken at SW location indicated also the presence of landfill material but this result did not justify the observed dose rates. Local survey with a portable dose rate meter indicated that measurements performed 30 m from the building showed background values on the range of 84 to 96 ngy h -1. As the fence is some 100m farther, it is clear that external exposures outside IRD are not affected by IRD activities. Figure 1 Sampling Points from IRD Environmental Monitoring Program

6 G D R NW W SW S SE E NE N gamma dose rate (ngy/h) Figure 2 Gamma dose rates ranges ( ngy h -1 ) - TLD results obtained by monitoring program for IRD For underground water, all spectrometric determinations were below detection limits and only natural radionuclides could be detected. Concentration in water is consistent with worldwide reference values [2]. Values upstream are however higher than those downstream IRD laboratories, probably reflecting the difference in the type of soil. Also for both lagoon water and sediments, only natural radionuclides could be detected (Table 3). Table 3 -- Summary of samples analysis results Sample Location 238 U 226 Ra 232 Th 40 K 7 Be Soil (Bq/kg) N 29 ± ± ± ± 32 < 14 soil (Bq/kg) S 14 ± 02 0,1 56 ± 5 82 ± 6 < 10 soil (Bq/kg) SW 32 ± ± ± ± 22 < 38 vegetation (Bq/kg) N ± ± ± ± ± 2100 vegetation (Bq/kg) S ± 0, ± ± ± ± 1300 Well water (Bq/L) SW 2E-3 ± 4E-4 9E-3 ± 2E-3 3E-4 ± 1E-5 < 2.4 < 1.5 Well water (Bq/L) E 2E-3 ± 1E-4 7E-3 ± 2E-3 2 E-4± 4E-6 <2.5 < 1.2 Lagoon water (Bq/L) Peninsula < ± < < 3 < 2 Lagoon sediment (Bq/L) Peninsula 23.1 ± ± 7.1 < ± 12.5 < CONCLUSION The IRD environmental monitoring program began in The first results are in agreement with those expected for the area. Anomalous measurements were observed at one location and further investigation has shown influence on gamma dose rates measures with TLD. A new TLD including neutron monitor will be included in this location routinely. Although the contribution to TLD readings is considerable, the contribution of neutron component to exposure is extremely low, and background levels can be assumed for all locations inside and

7 surrounding of IRD laboratories area. As it took some time to open the second well and we are still dependent on other institutions to comply with programmed measurement sites at the lagoon, few results are already available to adequately characterize the site. However, with results obtained by the program up to now, no environmental radiological impact could be observed, as expected. Some modifications on the original proposed program have been suggested. Main changes include the frequency of sampling of soil and sediments and the inclusion of more TLD stations inside the Institute. REFERENCES 1. Sachett, I.A. Caracterização da Radiação Gama Ambiental em Áreas Urbanas utilizando uma Unidade Móvel de Rastreamento. PhD thesis, Curso de pós-graduação em Biociências Nucleares, Instituto de Biologia, UERJ, January, UNSCEAR. Sources and Effects of Ionizing Radiation -- United Nations Scientific Committee on the effects of Atomic Radiation -- UNSCEAR 2000 report to the General Assembly with scientific annexes, United Nations, NY, 2000