Chapter 3

Radioactive Waste Management in Brazil Paulo Fernando Lavalle Heilbron Filho, Altair Souza de Assis, Jesus Salvador Perez Guerrero, Arnaldo Mezrahi, and Nerbe José Ruperti, Jr. Brazilian Nuclear Energy Commission (CNEN) Nuclear Safety and Radioprotection Directorate Rio de Janeiro, Brazil Contact: P.F.L. Heilbron, [email protected] 3.1.

INTRODUCTION

The Brazilian nuclear program involves the operation of several nuclear and radioactive installations. Two nuclear power plants are in operation and one is under construction. Angra 1 is a 657 MWe gross/626 MW net, 2-loop PWR and Angra 2 is a 1,345 MWe gross /1,275 MWe net, 4-loop PWR), both located in Angra dos Reis, in the state of Rio de Janeiro. A third facility, Angra 3, was a 1,312 MWe gross/1,229 MW net, 4-loop PWR, whose construction was interrupted in 1991 and has not yet resumed. The two now-functioning reactors are operated by the engineering company Eletrobras Termonuclear S. A. (ELETRONUCLEAR). At present, there are two functioning uranium mine and milling facilities operated by the Brazilian Nuclear Industry (INB). The first such mine was operational from 1982 until 1991 (in Poços de Caldas, located in the state of Minas Gerais). All the economically recoverable uranium has been extracted from that mine, and currently no mining activity is going on there. However, the uranium treatment facility there is still operational and has been used to process other source material from the second Brazilian mine, located in Caetité, in the state of Bahia. This second mine has the capacity for treating 100 t/yr of U3O8, as well as the production of lanthanum chloride and cerium hydroxide. A new mining facility, Catetité, operational since 2000, includes reserves of 100,000 tons of U3O8 and a capacity of 400 t/yr of yellow cake (U3O8), which can be expanded to 800 t/yr. Moreover, INB plans to open a fuel element

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complex (FEC) located in the state of Rio de Janeiro, which will include a reconversion and fuel-fabrication plant. This enrichment plant is expected to be in operation by end of year 2005. In addition, Brazil has four research reactors, all of which are owned and operated by CNEN. The first (and oldest in Latin America), IEA-R1, built in 1956 within the U.S. Atoms for Peace program, is located at the Nuclear and Energetic Research Institute (IPEN), on the São Paulo University campus at São Paulo. With a maximum power of 5 MW, it is used for physics experiments and radioisotope production, such as for I-131, Sm-153, and Mo-99. The second reactor, IPR-R1, a 100 kW Triga model, operating since 1960 at the Centro de Desenvolvimento de Tecnologia Nuclear (CDTN), is located on the campus of the Federal University of Minas Gerais, in Belo Horizonte, and is used mainly for research work. The first fuel-assembly replacement of the reactor is expected to occur in 2010. The third Brazilian Nuclear Research reactor, ARGONAUTA (built in 1965), located at the Institute of Nuclear Engineering (IEN) on the campus of the Federal University of Rio de Janeiro, can operate at a maximum power of 1 kW/h. This low reactor-burnup rate (approximately 0.25 MW/day—similar to IPR-R1) allows for efficient storage of spent fuel. This reactor is used for training, including sample irradiation. The last reactor, IPEN MB-01, also located at IPEN, is the result

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of a national joint program developed by CNEN and the Navy, and is a basic water-tank-type critical facility rated 100 W. This reactor is mainly used for simulation of low-level radioactive waste (LRW) and research in reactor physics (with a burnup rate of below 0.1 MW/day). Brazil’s nuclear program also includes: • Pilot-scale fuel-cycle facilities, including one plant for converting uranium to UF6 and another for uranium enrichment • 3,248 medical, industrial, and research facilities • One industrial facility for processing of monazite sands 3.2. WASTE CLASSIFICATION Brazil has adopted the radioactive waste classification system established by the International Atomic Energy Agency (IAEA), which organizes radioactive wastes into five categories, as shown on Table 3.1. (Note that those radionuclides designated “short-lived” are those with half-lives of ~30 years, such as Co-60, Sr-90, and Cs-137.).

The major sources of radioactive waste in Brazil are, at present: • The Angra I and II Nuclear Power Plants

Figure 3.1.

The Angra I and II Nuclear Power Plants

• The Monazite Processing Industry, which is being decommissioned • The 3,500 m3 of low-level waste resulting from the decontamination work performed in Goiânia, following the 1987 accident that involved a 1375 Ci therapy source (Group V) • The 3,248 medical, industrial, and research facilities (Groups I and V).

Table 3.1. IAEA Waste Classification Category

Characteristics

Disposal Options

Exempt Waste (IAEA-1987)

Activity levels equal to or below exemption limits based on a maximum impact dose of 0.01 mSy/y for the public Activity levels above exemption limit and heat generation equal to or below 2 kW/m3.

No radiological restriction

a. Short-lived waste

Long-lived alfa-emitter content equal to or below 4,000 Bq/g and an average specific activity of all radionuclides in the package (immobilized) of below 400 Bq/g).

Near-surface or geological repository (Lavie-1984, IAEA-1985, INTERA 1987, AECB-1985, AECB-1987, AECB-1998)

b. Long-lived waste

Radionuclide alfa-emitter concentration above limits cited before for short-live radioactive waste Heat generation above 2 kW/m3 and alfa-emitter concentration above the limits allowed for low- and intermediate-level waste—short lived( 2.1)

Geological repository (IAEA 1981, IAEA-1989) Geological repository (IAEA 1981, IAEA-1989)

Low- and IntermediateLevel Waste:

High-Level Waste

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Waste generated by the Uranium Mine and Milling Industrial Complex, although significant in volume, is kept at the site, in a dam especially built for this purpose (Group II). 3.3.

RADIOACTIVE WASTES FROM THE NUCLEAR POWER PLANT

From 1981 to 2003, the first Brazilian Nuclear Power Plant, Angra I—a Westinghouse two-loop pressurized water reactor of 626 Mwe (Figure 3.1)—generated a total of 1,953.3 m3 of solid/solidified waste, with an accumulated activity of ~304 TBq. Table 3.2 shows the quantities and percentages of low-level nuclear waste (LLW) and intermediate-level nuclear waste (ILW) generated by Angra I-NPP.

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Since the Brazilian reprocessing program has not yet been clearly defined, the Angra I spent fuel stored at the on-site reactor basin (containing 546 spent fuel elements) poses by far the most difficult disposal problem, both technically and politically. 3.4.

RADIOACTIVE WASTE FROM FUEL CYCLE AND MONAZITE PROCESSING FACILITIES The uranium mining and milling industrial complex (CIPC), located at the Poços de Caldas plateau in the Brazilian state of Minas Gerais, has produced, from 1982 to 1991, 1,170 tons of ammonium diuranate. The waste generated from this process is kept in a 29.2 hectar dam system, with an actual volume capacity of 1 million m3. It is estimated that 0.8 TBq (130 Ci) of U-238,

Table 3.2. Nuclear Power Plant Radioactive Waste Inventory Number of Packages Year

1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

Total m3 Bq

Cartridge Filters 2081 14 17 8 10 22 11 12 8 13 3 16 18 16 8 37 36 33 5 15 9 22 16 349 72.60 1.41 x 1013

Evaporator Noncompressible Spent Concentrates (1208l and 208 l) Resins 2081 2081 41 14 --23 52 129 155 116 179 68 485 315 279 129 194 197 108 72 19 21 62 52 2710 733.20 5.72 x 1013

--6 2 27 63 111 118 30 24 9 14 70 33 12 31 82 13 7 16 11 15 11 705 352.60 5.49 x 1012

----73 60 2 --109 1 0 28 --121 ----12 205 23 72 56 35 29 125 951 286.5 2.26 x 1014

Compressible 2081 *—**

Inactives 2081

74— 272—6 85—4 132—9 341—23 136—11 344—29 203—19 113—12 86—3 56—17 448—445 —196 —36 —495 —239 —125 —81 —148 —113 —113 —108 —2232 —464.30 1.58 x 1012

4 --3 18 27 20 11 21 21 12 --8 8 9 10 8 8 5 4 2 1 1 192 44.20 -----

* Before re-opening the drums for a better segregation ** After the new segregation

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authorization given to several manufacturers to use radioactive sources in lighting conductors. As a consequence, an estimated 75,000 of these devices installed throughout the country, with an overall activity on the order of 3.7 TBq (100 Ci) of Am-241, had to be recalled and stored by CNEN over the next five years.

Figure 3.2.

Waste dam at CIPC

15 TBq (405 Ci) of Ra-226, and 4.2 TBq (112 Ci) of Ra228 were disposed of at this site (Figure 3.2).

Most of the soluble radioactive wastes produced as a result of using short-lived radioisotopes in medical institutions and research laboratories can be discharged into sanitary sewerage systems, after a given decay period, with concentrations and total activities not exceeding the limits specified in the Brazilian regulations based on USA regulation limits (Code of Federal Regulation, 1987). To be on the conservative side, it was assumed that whole flask contents were not utilized. Moreover, in determining the recommended decay period, we had to take into account the time required for the specific activity of the contaminated empty flask (assumed to have 23 g and a remainder of 2% of the initial activity) to reach a value of 2 nCi/g (74 Bq/g), which is acceptable for dustbin disposal.

There are at present about 600 metric tons of “mesothorium,” with an estimated Ra-228 activity of 1.85 TBq (50 Ci) disposed of in a trench at CIPC, and 0.2 TBq (6 Ci) stored in a shed at USAM in São Paulo (78 m3). Although not forTable 3.3. Radioactive installations mally classified Figure 3.3 shows as waste, the the approximate Field Number Percent Medical 1,261 38.8 material with percentages of Industrial 984 30.3 thorium hydroxthe total spent ide, separated sources (47,062) Research 694 21.4 Distribution of Radionuclides 61 1.9 from the rare generated by sevServices 248 7.6 earth elements eral Brazilian during monazite states and stored Total 3,248 processing, is at CNEN's also in storage at many installations in Brazil. The waste research institutes, in rounded-off percentages (2,286 at volume generated by the fuel-elements assembly unit, as the IEN-RJ institute, 4,756 at CDTN-MG, and 40,020 at well as by all the other pilot-scale fuel-cycle facilities, is IPEN-SP). negligible compared to the above-mentioned figures. 3.6. RADIOACTIVE WASTES PRO3.5. RADIOACTIVE WASTE FROM DUCED AS A RESULT OF THE MEDICAL, INDUSTRIAL, AND GOIANIA ACCIDENT RESEARCH APPLICATIONS The violation of a teletherapy source in Goiânia, Brazil, There are at present 3,248 radioactive facilities in Brazil at the end of September 1987, with a subsequent spread that use several radionuclides. Table 3.3 shows the numof most of its radioactive contents (i.e., 1,375 Ci of Csber and percentage of these facilities, by field of appli137), over a large urban area, brought about the need to cation. It can be seen from Table 3.3 that most of the estimate the quantities recovered during the decontamiradionuclides have medical (~39%) and industrial nation work performed by CNEN (Figure 3.4). (~30%) applications. Approximately 3,500 m3 of wastes were generated, with an estimated overall activity lying between 47 TBq In 1989, the Brazilian Regulatory Body suspended the (1,270 Ci) and 49.6 TBq (1340 Ci). Accounting for the

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The waste was temporarily stored in open-air concrete platforms, occupying an area of about 8.5 x 106 m2 at a site near the village of Abadia de Goias and 23 km away from the center of Goiânia, a city with a population of ~1 million (Figure 3.5).

Figure 3.3.

Figure 3.4.

Taking into account the decay period necessary for the contents of all packages to reach a Cs-137 concentration level not greater than 87 Bq/g, it was possible to classify the drums and the metal boxes into five groups, as described in Table 3.3. According to the Number of spent sources generated per IAEA classification method, all radioactive state waste collected in Goiânia fell into the category of low-level, short-lived waste, and the IAEA disposal option for such waste is emplacement at shallow depths, in engineered storage facilities. It can be seen from Table 3.4 that approximately 33% of the waste volume (Group 1) has a specific radioactivity not greater than 87 Bq/g. Furthermore, most of the recovered activity is distributed over only 16.5% of the total volume, and will require a decay period greater than 150 years to reach acceptable concentration levels (Groups 4 and 5). (Heilbron et al., 1993)

Teletherapy equipment

decay period necessary for the contents of all packages to reach a Cs-137 concentration level not greater than 87 Bq/g, it was possible to classify the drums and metal boxes into five groups, as described in Table 3.4. The following packages were also used in Goiânia: • 1 metal package for the headstock with the remaining source (4.4 TBq and with 3.8 m3 from Group 5); •10 ship containers (374 m3 with 0.4 TBq from Group 1), and; • 8 special concrete packages (11.4 m3 and 0.7 Bq from Group 5).

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The remaining 40.8% of the waste volume (Groups 2 and 3) were recently placed in concrete containers—to improve its condition, as well as to provide an additional engineered barrier in the near-surface repository to be constructed. Moreover, although the specific radioactivity of the waste classified as Group 1 is less than the value established in the regulation for dust-bin disposal of solid wastes by users of radioisotopes, this group will not be considered exempt from control. The Brazilian Regulatory Body understands that the above-mentioned exemption criteria were established for solid wastes generated by facilities that handle small quantities of radioactive materials. It is also understood that care should be taken to avoid the deliberate fractioning and dilution of wastes, so as to achieve compliance with disposal regulations. One near-surface repository (CGP) was constructed in 1995 (Heilbron et al., 1994)—after exemption from the Brazilian Licensing Body (IBAMA)—for all the radioactive waste below the 87 Bq/g limit (Group 1); see Figure 3.6. Another repository was constructed in 1996 for radioactive waste from IAEA Groups 2–5 after

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licensing by IBAMA, based on the assessment of a specific Safety Analysis Report (based on U.S. 1987, U.S. 1988 documents); see Figure 3.7 (Heilbron et al., 1992). 3.7.

WASTE MANAGEMENT POLICY

As decreed by Brazilian legislation, the National

Figure 3.5.

Nuclear Energy Commission, CNEN, is the governmental body responsible for the receiving and final disposal of radioactive waste for all of Brazil. CNEN also holds national responsibility for the promulgation of regulations concerning waste management and disposal (CNEN-NE-6.05,1985, CNEN-NE-3.01,1988, CNEN-

Provisional storage at Abadia de Goiás

Table 3.4. Goiânia waste inventory Group Time in years (1) t=o (2)