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Environmental Monitoringand AssessmentAn International JournalDevoted to Progress in the Useof Monitoring Data in AssessingEnvironmental Risks to Manand the Environment ISSN 0167-6369 Environ Monit AssessDOI 10.1007/s10661-011-2274-5

Assessment of liquid disposal originatedby uranium enrichment at AramarExperimental Center São Paulo—Brazil

Marli Gerenutti, Marcos MoisésGonçalves, Sandra Regina Rissato, JoséMartins de Oliveira, Marco Antonio dosSantos Reigota, et al.

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Assessment of liquid disposal originated by uraniumenrichment at Aramar Experimental CenterSão Paulo—Brazil

Marli Gerenutti & Marcos Moisés Gonçalves & Sandra Regina Rissato &

José Martins de Oliveira Jr & Marco Antonio dos Santos Reigota &

Mário Sergio Galhiane

Received: 30 June 2010 /Accepted: 19 July 2011# Springer Science+Business Media B.V. 2011

Abstract This work presents a liquid disposal monitor-ing originated from uranium enrichment process atAramar Experimental Center from 1990 to 1998.Assessment of uranium, fluorides, ammoniacal nitrogen,chemical oxygen demand, and pH measurements weremade in water samples and compared with resultsachieved in other countries, as North America and India.The liquid disposal evaluation, generated by uraniumenrichment process, showed low levels, consideringmostparameters established by Federal and State Legislation,aiming environmental pollution control. However, urani-um levels were above the limits established by ConselhoNacional do Meio Ambiente, Environment ProtectionAgency and mainly by the World Health Organization.

Keywords Uranium . Environmental contamination .

Water analysis

Introduction

Among the Brazilian alternatives to large-scale energygeneration, nuclear power is very expensive, consid-ering the investments required by emergency systemssecurity, radioactive waste storage, and decommission-ing of nuclear power plant that has expired its lifetime(Valdović and Bošković 2000). There are severalelements for estimating decommissioning cost such aspre-actions, facility shutdown activities, procurementof general equipment and material, dismantling activ-ities, waste processing, packaging, transportation,storage and disposal, site security, surveillance andmaintenance, site restoration, cleanup and landscaping,project management, engineering, site support, socialmeasures, research and development, and fuel andnuclear material management (OECD/NEA 2006).

Uranium enrichment process gives rise to a largeamount of nearly pure U-238 that is useless as fuel innuclear reactors. For each kilogram of enricheduranium produced, 200 kg of low-enriched uraniumare generated, mainly U-238, a radionuclide that emitsa less harmful type of radiation but with a half-life ofabout 4.5 billion years. It is considered 40% lessradioactive than natural uranium, but its chemicaltoxicity is similar (Valdović and Bošković 2000).

Uranium has both radioactive and chemical toxicitythat mainly affect two vital organs: kidneys and lungs(Silva et al. 2000). The uptake of uranium in thekidneys has been attributed to the complexes formedwith proteins and phospholipids, which are considered

Environ Monit AssessDOI 10.1007/s10661-011-2274-5

M. M. GonçalvesSchool of Chemistry, Universidade Estadual de Campinas,Campinas, Brazil

M. Gerenutti (*) : J. M. de Oliveira Jr :M. A. dos Santos ReigotaSchool of Pharmacy, Universidade de Sorocaba,Av Dr Eugênio Salerrno, 100/140,18035-430 Sorocaba, Brazile-mail: marli.gerenutti@prof.uniso.br

S. R. Rissato :M. S. GalhianeSchool of Chemistry, Universidade Estadual Paulista,Bauru, Brazil

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major sites of damage in this organ. Uranium can alsoaffect the brain, changing neurological and pathologi-cal signs specially in cerebral cortex, such changeshave been observed in rats subjected to tests usinguranium salts. The tolerable daily uptake of uraniumestablished by World Health Organization is0.6 μg kg−1 bodyweight−1 (Gilman et al. 1998; WHO1998; WHO 2003). WHO, Health Canada and CON-AMA (Conselho Nacional do Meio Ambiente—Brazil)set the maximum concentration of uranium inwater respectively less than 9, 20, and 20 μg kg−1

(Gilman et al. 1998; WHO 1998).The main danger inherent to the disposal of atomic

waste is basically the environmental contamination.Water contamination is generally the most likelyform of pollution related to atomic waste disposal.Groundwater can get in contact with radioactiveelements that have percolated from atomic waste,contaminating water supplies from local or distantcommunities (ASTDR 1999).

Industries involved in the nuclear fuel cycle,including the uranium ore mining, milling, refining,conversion, fuel production, nuclear power genera-tion, and nuclear waste management are subjected tolicensing and control processes. The waste generatedby these activities require appropriate procedures forits treatment, before disposing them in the environment(IAEA 1995).

Unsuspected before, human activities have beenincreasing environmental radioactivity levels, being,nowadays, a potential source of exposure. Therefore,papers have been published on this topic, looking forthe development of technologies for remediation anddisposal treatment (Anderson et al. 2003; Wu et al.2006; Landa 2004).

Considering the environment, especially in areasclose to nuclear fuel cycle industries, complex rejectsgive rise to a dynamic equilibrium with largefluctuations in water quality. These fluctuations canbe fast or slow and are usually associated with theweather, including precipitation and hydrologicalphenomena, reflecting the toxicity of mine effluents(Antunes et al. 2007a; Carvalho et al. 2007a, b).

Sediments accumulate radionuclides by watersorption or by sedimentation of suspended radioactivesolids. The radionuclides that remain associated withsediments are strongly influenced by chemical,biochemical, and microbiological changes that occurin the environment (Valdović and Bošković 2000).

In order to evaluate the possible risks fromradioactivity uptake by humans through the foodchain, studies have been done on the absorption,concentration, retention, and release of radioactivematerials by aquatic organisms (Antunes et al. 2007b;Gudkov et al. 2008; Markich 2002).

Aiming to analyze the intensity and quantity ofchemical waste in Ipanema and Sorocaba rivers fromdisposal of atomic wastewater generated by enrichmentof uranium in Aramar Experimental Center (AEC),this paper presents a monitoring assessment ofliquid disposal from uranium enrichment process,from 1990 to 1998.

Experimental methods

Identification of AEC facilities

The Production Department named Centro Tecnológicoda Marinha in AEC—São Paulo had three divisions:manufacturing, assembly and enrichment. The enrich-ment division was composed by: operation of IsotopicEnrichment Laboratory (LEI), planning and control ofthe process, maintenance, decontamination, andstripping operation of pilot plants for isotopicenrichment (USIDE) and sectors to support the process.LEI and USIDE were the enrichment division unitschosen to be studied.

LEI may be considered responsible for the enrich-ment through the uranium hexafluoride ultracentrifu-gation process. The operation scale is related to thedevelopment and process demonstration, and it hasalso been used for testing equipment associated withthese procedures. This facility has been operatingsince 1988, producing UF6 enriched to the level of20% (by weight) of U-235 (CNEN 1985).

Samples

The evaluation of wastewater samples generated inthe AEC was performed by the RadioprotectionLaboratory (LARE), from 1990 to 1998.

For operational purposes, LEI monitoring for liquiddisposal, began in 1989 with the measurement offluoride and pH, in 1990 with uranium and biochemicaloxygen demand (BOD) analysis, in 1993 with measure-ment of ammonia nitrogen and sporadic monitoring ofiron and nickel (ARAMAR 1997).

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The liquid waste generated in LEI, consisted ofcitric solutions from decontamination operations,potassium hydroxide solutions from gas scrubbers,liquid Fomblin® from decontamination processes andwashing floor waters. Figure 1 shows the sequencefor the decontamination of ultracentrifuge parts andplastic containers. The waste generated in these caseswas accumulated in the tanks 5 and 6.

Citric solutions with large amount of uranium werestored and transported in plastic containers to thermosolar evaporator and other solutions were deliveredthrough specific pipes to the collection, storage, andreject processing systems (ARAMAR 1997).

The liquid streams generated during normal operationof USIDE were originated by the fan coils condensedwaters, water from washbasins, showers and drains ofrestricted areas, and solutions from gas scrubbers.

Whereas the main contaminant was uranium, thewaste was transported to the tanks, and rejectswith radiation levels higher than 2.6×10−6 Bq g−1

should be transferred to the LEI thermo solarevaporators. Monitoring of the USIDE effluents hasstarted in the second half of 1996 with uranium,fluorides, ammonia nitrogen and BOD analysis, aswell as pH measurement.

To determine physical and chemical parameters, allsamples were collected and stored in a refrigerator inglass bottles at 4°C until analysis.

Thus, all samples were submitted to specificanalysis, in order to obtain authorization to releasethe disposal contained in the collection and storagetanks. According to AEC procedure, whenever thedisposal condition was unsatisfactory, its subsequentdisposal occurred after appropriate treatment.

A. DECONTAMINATION

BMOBEUGUFIRTNECARTLU

1. Dismantling.

2. Parts.

2.1. Mechanic devices.

• Citric acid ultrasound immersion; • Water washing; • Acetone drying; • Monitoring and packaging.

1. Dismantling.

2. Gas scrubber.

• Two hot cycles without drainage with Sun; • Drainage in plastic cilinder; • Hot water washing; • Drainage in plastic cilinder;

3. Immersion in ultrasound with citric

acid;

4. Washing and oxidation removal;

5. Drying, monitoring and packaging.

B. LIQUID EFFLUENTS (TANKS 5 AND 6)

2.2. Stators and other electronics.

• 7.5% citric acid wet paper cleaning; • 10% (NH4)2CO3 wet tissue paper cleaning;• Acetone wet tissue or paper cleaning (drying step).

3. Drying, monitoring and packaging.

6. Plastic barrel gathered material to

be conducted to thermo solar

evaporator.

C. SOLID RESIDUE

⇓

⇓

Fig. 1 Decontaminationsequence for ultracentri-fuges and bombs

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Liquid disposal analysis

For monitoring the chosen parameters, LARE hasused internationally recognized methods, which aredescribed below:

Uranium

The determination of uranium in liquid or gasdisposals was achieved by using gravimetric orfluorimetric analysis. In LARE, from 1990 to 1998,the monitoring of uranium in the liquid disposal wasmade through fluorimetric analysis and the resultswere expressed in μg L−1 or μg g−1.

Fluorides

Among the methods suggested for determiningfluoride ions in water, the most satisfactory were thepotentiometric and colorimetric ones. In LARE,fluoride monitoring in liquids was performed bypotentiometric analysis and the results were expressedin μg g−1 or μg L−1.

Ammonia nitrogen

In general, ammonia nitrogen determination wasdirectly and manually made in drinking water,surface water, from lakes and rivers. However,when high precision determination was required,there was a need for preconcentration. Colorimetricwith Nessler reagent and gravimetric methods wereused (CNEN 1985; ARAMAR 1997).

For ammonia detection the following methodshave been used: titrimetric (concentrations higherthan 5 mg L−1), ammonia-selective electrode method(NH3 concentrations of 0.03 to 1 400 mg L−1), phenatemethod (NH3 linear concentrations of 0.6 mg L−1), andautomated phenate method (NH3 concentrationsbetween 0.02 and 2.0 mg L−1).

pH

The method for pH measurement was the electro-metric one, using potentiometric determinationwhich employed standard hydrogen electrode andreference electrode. In LARE, AEC liquid disposalmeasurement was performed by potentiometricanalysis.

Chemical oxygen demand

Was performed by potassium dichromate reflux(titrimetric analysis), which is the most suitable,due to its high oxidant capacity. The analysis ofliquid disposal was performed by closed refluxmethod (titrimetric and colorimetric methods), dueto economic advantages.

Results and discussion

The quality of water and wastewater can be repre-sented by various parameters, which reflect the mainphysical, chemical and biological features of theenvironment.

The liquid disposal generated in the uraniumenrichment process has acquired features accordinglyto the procedure employed. The requirements to bemet for the liquid disposal are subject to specificlegislation, which provides quality standards for theliquid disposal and the environment involved. Theremoval of pollutants in treatment was made in orderto reach a desired quality or quality standard, and it islinked to current concepts of level and treatmentefficiency (APHA 1998).

Patterns of effluent release become increasinglyrestricted, and there is the need to recycle water, thuspreserving water sources and, at the same time,providing an effective use of that resource. Therefore,the treatment degree required for a reject alwaysdepends on the environment, the features of thedownstream water from its releasing point, the selfpurification features and the environmental waterdilution (Valdović and Bošković 2000; IAEA 1995).The use of polymer materials showed positive resultsin effluent treatment generated by nuclear reactors(Preetha et al. 2006).

This paper presents a monitoring of liquid disposalreleased in Ipanema and Sorocaba rivers, generated byuranium enrichment process at Aramar ExperimentalCenter, from 1990 to 1998. Ipanema and Sorocaba(Fig. 2) rivers are classified as class 2, with waterintended, after conventional treatment, to domesticsupply, vegetable and tree fruit irrigation, and primarycontact recreation (São Paulo 1976; CONAMA 2005a;CONAMA 2005b; CONAMA 2008).

According to Table 1, the results showed that thesemestral volume of liquid released by LEI and

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USIDE were considered lesser than the amountsallowed by Federal and State laws, considering thefeatures of Sorocaba River is thus in accordance withthe legislation (São Paulo 1991).

Table 2 shows the semestral average concentra-tion of fluorides and ammonia nitrogen released inLEI's liquid disposal, and the values of pH and CODfrom 1990 to 1998. Considering the quality standardin Class 2 rivers and the liquid disposal releasestandard, CONAMA 357/2005 (Article 34, FluentRelease Patterns) (CONAMA 2008), the maximumconcentration of fluoride released in USIDE and LEIliquid effluents did not exceed the concentrationlimit recommended (Table 2), i.e., 10 mg L−1.

However, according to the World Health Organiza-tion, the fluoride level established as optimal fordrinking water ranges from 0.7 to 1.2 mg L−1, accordingto the mean annual temperature (18°C=1.2, 19–26°C=0.9, 27°C=0.7 mg L−1). The maximum levels of

fluoride in drinking water are set according to theconsumer age, and the daily amount of water intake.

In tropical countries, where the daily water intakeis higher, the fluoride control should be more rigorousconcerning public water supply. However, whenthe fluoride concentration exceeds the limitsestablished by existing laws, drinking water mustbe defluorinated, due to the possibility of causingdental and skeletal fluorosis, in both humans andanimals (Bucher et al. 1991).

Evaluation of ammonia nitrogen is very important,because at high concentrations, it exhibits hightoxicity for fish, in general. The average concentra-tions of ammonia nitrogen, released in liquid disposalof LEI and USIDE, have had values below themaximum concentration of 20 mg L−1 (Table 2)(CONAMA 2008).

Similarly, the pH measurement is one of mostrelevant analysis often used for chemical water

Fig. 2 Sorocaba andIpanema rivers(Smith 2003)

7Q10 monthly average flow

(m3 s−1)7Q10 estimated

(m3 h−1)7Q10 excellent

(m3 h−1)

Sorocaba river higher (851 km2) 4.70 16,920.00 11,764.90

Sorocaba/Pirajibu 8.86 31,896.00 34,000.27

Sorocaba river lower (3,109 km2) 13.94 50,184.00 46,621.68

Table 1 7Q10 valuesconsidering Sorocabariver

7Q10 estimation of mini-mum 7-day, 10-yeardischarge

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testing. Virtually, in all reservoirs or water treatmentplants, the acid–base balance, filtration, precipitation,coagulation, disinfection and corrosion control arepH dependent. The pH influences the physico-chemical equilibrium, driving it to more or less toxicchemical species.

Fish life becomes almost impossible if the pH isbelow 6.0 or above 9.0. At a pH lower than 6.0, thebalance bicarbonate/carbon dioxide is shifted towardscarbon dioxide, which becomes toxic to fish, from100 mg L−1. At pH greater than 8.0 there is a releaseof molecular ammonia, more toxic than its ion, andthe limit for fish death lies between 0.2 and2.0 mg L−1 (Rand and Petrocelli 1985). In thiscontext, practically all the pH values in LEI liquid

disposal between 1990 and 1998 were within theallowed ones (Table 2) (CONAMA 2008).

Determination of uranium is vital for assessingenvironmental pollution, not only by its presencein water (especially water springs) and soil, butalso because of its decay, which generates consid-erable levels of radioactivity in the environment(Dong et al. 2006) (this type of contamination isconsidered persistent, because uranium-238 has ahalf-life of ∼4.5 billion years, while uranium-235 has ahalf-life of approximately 0.7 billion years).

However, information on uranium toxicity is limitedand some studies have shown that its toxicity mainlydepends on many variables, mostly pH and carbonates(Shepard et al. 2005; ICRP 1993). Several international

Table 2 Semestral monitoring of LEI liquid effluent, tanks 5 and 6

Fluorides (mg L−1) Ammonia nitrogen (mg L−1) COD (mg L−1 O2) pH

Tank 5 Tank 6 Tank 5 Tank 6 Tank 5 Tank 6 Tank 5 Tank 6

1998

1st sem 0.55±0.77 0.33±0.27 0.12±0.09 0.12±0.09 23.62±12.39 25.83±27.00 8.5–5.9 8.1–6.4

1997

2nd sem 1.99±0.57 1.02±0.53 0.16±0.28 0.39±0.45 30.07±21.46 39.76±35.12 8.2–6.6 8.4–6.6

1st sem 0.66±0.21 0.70±0.20 0.16±0.20 0.07±0.05 27.25±30.49 18.34±10.97 8.0–6.5 7.6–6.8

1996

2nd sem 1.55±0.91 1.53±0.43 0.18±0.11 0.14±0.08 18.61±5.39 18.00±4.50 7.9–6.6 7.9–6.5

1st sem 0.94±0.36 0.72±0.29 0.31±0.16 0.32±0.17 30.54±23.68 22.88±10.65 7.5–6.7 7.8–6.7

1995

2nd sem 0.87±0.45 0.79±0.31 0.37±0.19 0.60±0.42 23.18±11.22 45.36±35.69 7.9–6.5 7.5–6.7

1st sem 0.88±0.26 1.01±0.57 0.35±0.14 0.33±0.15 17.46±5.69 17.38±6.14 7.4–6.6 7.6–6.6

1994

2nd sem 2.44±1.04 2.32±0.87 0.60±0.91 0.46±0.55 49.15±37.28 45.07±31.81 7.8–6.9 7.7–6.7

1st sem 1.22±0.59 1.45±0.73 0.54±0.49 0.33±0.15 39.07±30.47 39.28±26.12 7.5–6.1 7.5–6.2

1993

2nd sem 1.16±0.56 1.03±0.56 0.33±0.24 0.51±0.36 37.84±15.07 33.00±23.57 7.5–6.4 7.4–6.1

1st sem 0.95±0.65 0.72±0.48 0.60±0.43 0.49±0.34 39.14±33.30 35.53±34.68 7.5–5.5 7.3–6.4

1992

2nd sem 0.73±0.41 0.62±0.14 – – 31.63±11.20 31.63±11.28 7.6–6.1 7.5–6.2

1st sem 0.67±0.19 0.63±0.23 – – 13.66±10.26 28.00±15.71 7.5–6.3 7.7–6.2

1991

2nd sem 0.15±0.21 0.52±0.10 – – 58.90±46.49 33.36±27.75 7.6–6.3 7.7–6.8

1st sem 0.50±0.02 0.50±0.01 – – 9.04±7.95 7.874±6.85 7.8–5.3 7.4–6.1

1990

2nd sem 0.53±0.12 0.50±0.01 – – 76.00±9.53 95.66±19.42 7.3–5.3 7.5–6.3

Means and standard deviations of fluorides and ammonia nitrogen concentrations, chemical oxygen demand (COD), and theirrespective pH range variations

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agencies on health and environmental protectionhave recommended maximum concentration limitsfor uranium in drinking water or water springs forconsumption. The International Commission onRadiological Protection (ICRP 1993) recommendedthe maximum limit in water of 0.0019 mg L−1 andWHO (2004) the maximum of 0.015 mg L−1 used forwater springs for consumption. However, accordingto CONAMA Resolution no. 357/05, Article 15(freshwater class 2) (CONAMA 2005b), the standarduranium emissions was set at 0.002 mg L−1.

Table 3 shows the monitored uranium presentedconcentrations from 1990 to 1998, assessed in LEI forliquid disposals. The amounts of uranium rangedfrom 0.105 to 0.635 mg L−1 for liquid disposals.

These results indicate that uranium concentrationswere discovered to be above the limit of 0.020 mg L−1

recommended by CONAMA (2005b) and 0.030 mg L−1

by US EPA (2003) and specially 0.015 mg L−1 byWHO (2004). However, when compared with valuesobtained in international literature, the resultsappear to be close to values of 0.973 mg L−1

obtained both in North America's (US EPA 1990; 1991)and 0.471 mg L−1 in the India's spring waters(Bansal et al. 1988).

Conclusions

Liquid disposal effluent evaluation generated by urani-um enrichment processes at AEC, for most parameters,showed results below the limits prescribed by BrazilianFederal and State legislation to control environmentalpollution. The results for uranium in liquid were above

Uranium Concentrations (mg L-1) in Liquid Effluents

Tank 5 Tank 6 Total

1998

1st sem 0.256±0.323 0.243±0.378 65.51

1997

2nd sem 0.384±0.310 0.523±0.431 105.06

1st sem 0.105±0.060 0.194±0.149 33.09

1996

2nd sem 0.535±0.274 0.614±0.425 140.40

1st sem 0.430±0.372 0.373±0.214 75.40

1995

2nd sem 0.453±0.265 0.432±0.355 81.30

1st sem 0.216±0.153 0.364±0.318 79.40

1994

2nd sem 0.599±0.319 0.635±0.393 137.40

1st sem 0.444±0.337 0.477±0.393 146.32

1993

2nd sem 0.350±0.389 0.411±0.323 80.44

1st sem 0.341±0.300 0.334±0.288 73.11

1992

2nd sem 0.420±0.236 0.524±0.239 100.30

1st sem 0.208±0.215 0.279±0.251 90.90

1991

2nd sem 0.241±0.186 0.209±0.150 75.94

1st sem 0.045±0.065 0.050±0.119 10.42

1990

2nd sem 0.082±0.120 0.062±0.064 9.68

Table 3 Semestral uraniummonitoring from LEIliquid effluents

Means and standard devia-tions of uranium concentra-tions and the total semestralamount of uraniumdelivered

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the limits recommended by CONAMA (0.020 mg L−1)and EPA (0.030 mg L−1), and mainly by WHO(0.015 mg L−1), but were close to the values obtainedin international literature for spring waters.

This paper gives evidence to the importance ofmonitoring the effluent generated by the uraniumenrichment and suggests the need to expand itsmonitoring through environmental samples as foun-tainheads, sediments, soil, and biota next to nuclearfacilities, in order to create real parameters for thepopulation health as well as the environmentalprotection.

Acknowledgment The authors are grateful to CNPq-ConselhoNacional de Desenvolvimento Científico e Tecnológico, forfinancial support.

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