Decontamination of radiological agents from drinking water infrastructure: a literature review and summary.

This report summarizes the current state of knowledge on the persistence of radiological agents on drinking water infrastructure (such as pipes) along with information on decontamination should persistence occur. Decontamination options for drinking water infrastructure have been explored for some important radiological agents (cesium, strontium and cobalt), but important data gaps remain. Although some targeted experiments have been published on cesium, strontium and cobalt persistence on drinking water infrastructure, most of the data comes from nuclear clean-up sites. Furthermore, the studies focused on drinking water systems use non-radioactive surrogates. Non-radioactive cobalt was shown to be persistent on iron due to oxidation with free chlorine in drinking water and precipitation on the iron surface. Decontamination with acidification was an effective removal method. Strontium persistence on iron was transient in tap water, but adherence to cement-mortar has been demonstrated and should be further explored. Cesium persistence on iron water infrastructure was observed when flow was stagnant, but not with water flow present. Future research suggestions focus on expanding the available cesium, strontium and cobalt persistence data to other common infrastructure materials, specifically cement-mortar. Further exploration chelating agents and low pH treatment is recommended for future decontamination studies.

Production and dosimetric aspects of the potent Auger emitter 58mCo for targeted radionuclide therapy of small tumors.

PURPOSE: Based on theoretical calculations, the Auger emitter 58mCo has been identified as a potent nuclide for targeted radionuclide therapy of small tumors. During the production of this isotope, the coproduction of the long-lived ground state 58gCo is unfortunately unavoidable, as is ingrowth of the ground state following the isomeric decay of 58mCo. The impact of 58Co as a beta(+)- and gamma-emitting impurity should be included in the dosimetric analysis. The purpose of this study was to investigate this critical part of dosimetry based on experimentally determined production yields of 58mCo and 58gCo using a low-energy cyclotron. Also, the cellular S-values for 58mCo have been calculated and are presented here for the first time. METHODS: 58mCo was produced via the 58Fe(p,n)58mCo nuclear reaction on highly enriched 58Fe metal. In addition, radiochemical separations of produced radio-cobalt from natFe target material were performed. The theoretical subcellular dosimetry calculations for 58mCo and 58gCo were performed using the MIRD formalism, and the impact of the increasing ground state impurity on the tumor-to-normal-tissue dose ratios (TND) per disintegration as a function of time after end of bombardment (EOB) was calculated. RESULTS: 192 +/- 8 MBq of 58mCo was produced in the irradiation corresponding to a production yield of 10.7 MBq/microAh. The activity of 58gCo was measured to be 0.85% +/- 0.04% of the produced 58mCo activity at EOB. The radio-cobalt yields in the rapid separations were measured to be > 97% with no detectable iron contaminations in the cobalt fractions. Due to the unavoidable coproduction and ingrowth of the long-lived ground state 58gCo, the TND and the potency of the 58mCo decrease with time after EOB. If a future treatment with a 58mCo labeled compound is not initiated before, e.g., 21 h after EOB, the resulting TND will be approximately 50% of the TND of 'pure' 58mCo as a result of the increased normal tissue dose from the ground state. CONCLUSIONS: The Auger emitter 58mCo is a potent radioisotope for targeted radionuclide therapy, and the production of therapeutic quantities should be achievable using a small biomedical cyclotron. However, the unavoidable coproduction and ingrowth of the long-lived ground state 58gCo requires fast radiochemical processing and use of future 58mCo-labeled radiopharmaceuticals in order to exploit the high achievable TND of 58mCo.

Treatment of radioactive liquid waste (Co-60) by sorption on Zeolite Na-A prepared from Iraqi kaolin.

Iraqi synthetic zeolite type Na-A has been suggested as ion exchange material to treat cobalt-60 in radioactive liquid waste which came from neutron activation for corrosion products. Batch experiments were conducted to find out the equilibrium isotherm for source sample. The equilibrium isotherm for radioactive cobalt in the source sample showed unfavorable type, while the equilibrium isotherm for the total cobalt (the radioactive and nonradioactive cobalt) in the source sample showed a favorable type. The ability of Na-A zeolite to remove cobalt from wastewater was checked for high cobalt concentration (822 mg/L) in addition to low cobalt concentration in the source sample (0.093 mg/L). A good fitting for the experimental data with Langmuir equilibrium model was observed. Langmuir constant qm which is related to monolayer adsorption capacity for low and high cobalt concentration was determined to be 0.021 and 140 mg/g(zeolite). The effects of important design variables on the zeolite column performance were studied these include initial concentration, flow rate, and bed depth. The experimental results have shown that high sorption capacity can be obtained at high influent concentration, low flow rate, and high bed depth. Higher column performance was obtained at higher bed depth. Thomas model was employed to predict the breakthrough carves for the above variables. A good fitting was observed with correlation coefficients between 0.915 and 0.985.

Selectivity of 90Sr urine bioassay technique over 241Am, 238/239PU, 210PO, 137CS and 60CO.

The selectivity of a rapid (90)Sr bioassay technique over (241)Am, (238/239)Pu, (210)Po, (137)Cs and (60)Co has been investigated. Similar to (90)Sr, these radionuclides are likely to be used in radiological dispersive devices. The purpose of this study was to demonstrate the degree to which the (90)Sr bioassay technique is free from interference by these radionuclides if present in a urine matrix. The interfering radionuclides were removed (from (90)Sr) by their retention on an anion exchange column. While, recovery of the target radionuclide ((90)Sr) was found to be >or= 90 %, contributions from (241)Am, (242)Pu and (208)Po were found to be

Development of simulated air filters for gamma-ray spectrometry proficiency testing.

A set of 60 spiked simulated air filter sources was developed for the 2004-2005 proficiency test of the Italian radioactivity surveillance network. Each simulated filter source was prepared by reproducible volumetric dispensing of 19 drops of a mixed radioactive solution containing Co-57, Cs-134, Cs-137, Co-60 and Eu-152. The spiking pattern was investigated and optimized by numerical simulations. The filter sources were checked by double counting on HPGe and NaI(Tl) detectors. The standard deviation (SD) of activity values was 1.5%.

Evaluation of Cuprimine and Syprine for decorporation of (60)Co and (210)Po.

The acknowledged risk of deliberate release of radionuclides into local environments by terrorist activities has prompted a drive to improve novel materials and methods for removing internally deposited radionuclides. These decorporation treatments will also benefit workers in the nuclear industry, should an exposure occur. Cuprimine and Syprine are oral therapeutics based on the active ingredients D-penicillamine and N,N'-bis-(2-aminoethyl)-1,2-ethanediamine dihydrochloride, respectively. These therapeutic drugs have been used for several decades to treat Wilson's disease, a genetic defect leading to copper overload, by chelation and accelerated excretion of internally deposited copper. Studies were undertaken to evaluate these FDA-approved drugs for the in vivo decorporation of radioactive cobalt (Co) and polonium (Po) using male Wistar-Han rats. In these studies, Co or Po was administered to animals by IV injection, followed by oral gavage doses of either Cuprimine or Syprine. Control animals received the radionuclide alone. For Co studies, animals received a single dose of Cuprimine or Syprine, while for Po studies animals were repeatedly dosed at 24-h intervals for a total of 5 doses. Results show that Syprine significantly increased urinary elimination and skeletal concentrations of Co compared to controls. While Cuprimine had little effect on total excretion of Co, the skeletal, kidney, liver, muscle, and stomach tissues had significantly lower radioactivity compared to control animals. The low overall excretion of Po made it difficult to reliably measure urinary or fecal radioactivity and draw a definitive conclusion on the effect of Cuprimine or Syprine treatment on excretion. However, Cuprimine treatment was effective at reducing spleen levels of Po compared to controls. Similarly, Syprine treatment produced statistically significant reductions of Po in the spleen and skeletal tissues compared to control animals. Based on these promising findings, further studies to evaluate the dose-response pharmacokinetic profiles for decorporation are warranted.

Removal of radiocobalt from EDTA-complexes using oxidation and selective ion exchange.

Methods for the removal of radiocobalt from an ethylenediaminetetraacetic acid (EDTA) complex of Co(II) (aqueous solution containing 10 microM Co(II) and 10 microM or 50 microM EDTA traced with (57)Co) are presented. The studies examined a combination of different oxidation methods and the sorption of (57)Co on a selective inorganic ion exchange material, CoTreat. The oxidation methods used were ultraviolet (UV) irradiation with and without hydrogen peroxide (H(2)O(2)), as well as ozonation alone or in combination with UV irradiation. Also, the possible contribution of Degussa P25 TiO(2) photocatalyst to degradation of EDTA was studied. The best results for the equimolar solution of Co(II) and EDTA were achieved by combining ozonation, UV irradiation, Degussa P25 TiO(2) and CoTreat, with approximately 94% sorption of (57)Co. High values for the (57)Co sorption were also achieved by ozonation ( approximately 88%) and UV irradiation (approximately 90%) in the presence of CoTreat and Degussa P25 TiO(2). A surplus of EDTA over Co(II) was also tested using 10 microM Co(II) and 50 microM EDTA. Only a slight decrease, to approximately 88% sorption of (57)Co, was detected compared to the value (approximately 90%) obtained with 10 microM EDTA.

Sorption of radiocobalt and its EDTA complex on titanium antimonates.

The sorption properties of two synthesized titanium antimonate materials were tested in simulated nuclear power plant decontamination solutions. The aim was the removal of radiocobalt in the presence of complexing agents such as EDTA and oxalate. The first titanium antimonate material had a mixture of pyrochlore and rutile structures and it showed good tolerance for the complexing agents. 91% of cobalt was removed in the presence of EDTA, and oxalic acid had only a minor effect on the sorption. The other material, which had a mopungite structure, tolerated EDTA well (97% removal of cobalt) but its sorption properties for cobalt were restricted to a specific amount of oxalic acid. The sorption efficiency of cobalt increased for both materials when the cobalt concentration was less than 1 microM, indicating that the synthesized materials are efficient sorbents, especially for trace amounts of radiocobalt.

Enzymatic extraction of cobalamin from monoclonal antibody captured haptocorrin and transcobalamin.

OBJECTIVES: Current extraction methods for cobalamins from serum influence the molecular characteristics of the vitamin. Therefore, an extraction procedure that leaves the cobalamins unchanged is needed. DESIGN AND METHODS: Monoclonal antibodies towards transcobalamin (TC) and haptocorrin (HC) (in house) linked to magnetic microspheres were used for precipitation of the proteins. The cobalamins were subsequently released by degradation of TC or HC with subtilisin Carlsberg (EC.3.4.21.14). RESULTS: Recovery for the extraction of (57)Co-cyanocobalamin ((57)Co-hydroxycobalamin) was higher than 99 (93)% and 92 (93)% from TC and HC respectively (n=10 (3)). No change in retention time and recovery was observed for (57)Co-hydroxycobalamin analyzed with HPLC before and after extraction with subtilisin Carlsberg. Endogenous cobalamin in serum was extracted from TC and HC and measured with routine methods. Enzymatic extracted cobalamin constituted 118-187% of that measured in serum with routine methods (n=16). CONCLUSION: We present a method that allows extraction of cobalamins from their binding proteins without modifying the vitamin. The procedure may be useful especially for extractions aiming at characterizing the cobalamins bound to individual cobalamin binding proteins.

Simultaneous production of high specific activity 64Cu and 61Co with 11.4 MeV protons on enriched 64Ni nuclei.

The (64)Cu and (61)Co radionuclides were produced simultaneously by irradiation of enriched (64)Ni on a low energy proton-only cyclotron. Nickel targets were prepared by electrodeposition of enriched (64)Ni (>95%) on Au backing at thicknesses of 25-225 mg/cm(2) with efficiencies >99%. Irradiations up to 30 microA for 8h were performed with 11.4 MeV protons using a water-cooled target mounting. Radiochemical separation of (64)Cu and (61)Co from (64)Ni was performed by chromatography of the chlorocomplexes in a single step using an anion exchange resin column with a yield >95%. Using this method, the Ni target material was recovered and re-plated for subsequent production runs with an overall efficiency >96%. The excitation function for the (64)Ni(p,n)(64)Cu reaction was measured and compared with published values. Experimental thick target saturation yields of 159 mCi/microA for (64)Cu and 715 microCi/microA for (61)Co were achieved. Typical specific activities of (64)Cu were found to be 18.8+/-3.3 Ci/micromol.

Preparation and evaluation of cerium(IV) tungstate powder as inorganic exchanger in sorption of cobalt and europium ions from aqueous solutions.

Cerium(IV) tungstate powder was chemically synthesized and exploited as adsorbent material for the decontamination study of cobalt and europium ions from radioactive waste solutions under simulated conditions using batch technique. The influences of pH, particle size and temperature have been reported. The uptake of europium was found to be slightly greater than that of cobalt and the apparent sorption capacity increases with increase in temperature. Thermodynamic parameters such as changes in Gibbs free energy (DeltaG degrees), enthalpy (DeltaH degrees), and entropy (DeltaS degrees) were calculated. The numerical value of DeltaG degrees decreases with an increase in temperature, indicating that the sorption reaction of each ion was spontaneous and more favorable at higher temperature. The positive values of DeltaH degrees correspond to the endothermic nature of sorption processes and suggested that chemisorption was the predominant mechanism. A comparison of kinetic models applied to the sorption rate data of each ion was evaluated for the pseudo first-order, the pseudo second-order, intraparticle diffusion and homogeneous particle diffusion kinetic models. The results showed that both the pseudo second-order and the homogeneous particle diffusion models were found to best correlate the experimental rate data. The numerical values of the rate constants and particle diffusion coefficients were determined from the graphical representation of the proposed models. Activation energy (E(a)) and entropy (DeltaS++) of activation were also computed from the linearized form of Arrhenius equation.

60Co aqueous speciation and pH effect on the adsorption behavior on inorganic materials.

The adsorption of radioactive cobalt from aqueous solution on MgO, MnO(2), TiO(2), SnO, activated carbon and calcined hydrotalcite was studied under static conditions as a function of pH (1, 3, 5, 7, and 10) of the (60)Co solution. It was found that under the experimental conditions, (60)Co was significantly adsorbed on MnO(2), TiO(2) and activated carbon and in smaller quantities on MgO, SnO and calcined hydrotalcite. The adsorption of (60)Co species on MgO, MnO(2), TiO(2) and SnO can be attributed to the direct exchange of ions with a specific group on the adsorbing surface, in accordance with the concept of zero point charge (zpc). The radionuclide content was determined by gamma-spectrometry. The (60)Co chemical species present in aqueous solutions with different pH values were surveyed by using high-voltage electrophoresis. It was also found that (60)Co was present only as a cationic species at pH 1, 3, 5 and 7 and a neutral species at alkaline pH.

Measurement of residual 60Co activity induced by atomic-bomb neutrons in Nagasaki and background contribution by environmental neutrons.

Residual 60Co activity in five steel samples induced by neutrons from the Nagasaki atomic bomb has been measured within about 1000 m from the hypocenter. The chemical separation of cobalt and nickel from steel samples was performed, and cobalt-enriched samples were prepared for all samples. Gamma-ray measurements were carried out with a low-background well-type germanium detector. The gamma-ray spectra for five samples were compared with the spectrum of a control sample to ensure that the observed 60Co was actually induced by A-bomb neutrons. The activation of cobalt by environmental neutrons was also investigated. It has been shown that the present 60Co data are consistent with earlier Hashizume's data.

Synergistic effect of some pharmaceutical compounds on cobalt-60 complexes.

Synergism in the extraction of cobalt from acetate 0.1 M aqueous medium, pH = 5.3 has been investigated using a mixture of thenoyl-trifluoro acetone and antipyrine, 4-iodoantipyrine or 4-aminopyrine (AAPy), synergism was observed in all the cases. The maximum synergistic effect was observed in the case of 4-(AAPy). The nature of the extracted species has been determined and the equilibrium constants for the adducts have been evaluated. The thermodynamic parameters of these reactions have been calculated to elucidate the mechanism of formation of the extracted species. These compounds were found to be good donors capable in strength to other alkyl phosphorus donors.

The measured radiation environment within Spacelabs 1 and 2 and comparison with predictions.

To measure the radiation environment in the Spacelab (SL) module and on the pallet, a set of passive and active radiation detectors was flown as part of the Verification Flight Instrumentation (VFI). SL 1 carried 4 passive and 2 active detector packages which, with the data from the 26 passive detectors of Experiment INS006, provided a comprehensive survey of the radiation environment within the spacecraft. SL 2 carried 2 passive VFI units on the pallet. Thermoluminescent dosimeters (TLDs) measured the low linear energy transfer (LET) dose component; the HZE fluence and LET spectra were mapped with CR-39 track detectors; thermal and epithermal neutrons were measured with the use of fission foils; metal samples analyzed by gamma ray spectroscopy measured low levels of several activation lines. The TLDs registered from 97 to 143 mrad in the SL 1 module. Dose equivalents of 330 +/- 70 mrem in the SL 1 module and 537 +/- 37 mrem on the SL 2 pallet were measured. The active units in the SL 1 module each contained an integrating tissue-equivalent ion chamber and two differently-shielded xenon-filled proportional counters. The ion chambers accumulated 125 and 128 mrads for the mission with 17 and 12 mrads accumulated during passages through the South Atlantic Anomaly (SAA). The proportional counter rates (approximately 1 cps at sea level) were approximately 100 cps in the middle of the SAA (mostly protons), approximately 35 cps at large geomagnetic latitudes (cosmic rays) and approximately 100 cps in the South Horn of the electron belts (mostly bremsstrahlung). Detailed results of the measurements and comparison with calculated values are described.