Flavia Groppi

Tracking of Airborne Radionuclides from the Damaged Fukushima Dai-Ichi Nuclear Reactors by European Networks

Radioactive emissions into the atmosphere from the damaged reactors of the Fukushima Dai-ichi nuclear power plant (NPP) started on March 12th, 2011. Among the various radionuclides released, iodine-131 ((131)I) and cesium isotopes ((137)Cs and (134)Cs) were transported across the Pacific toward the North American continent and reached Europe despite dispersion and washout along the route of the contaminated air masses. In Europe, the first signs of the releases were detected 7 days later while the first peak of activity level was observed between March 28th and March 30th. Time variations over a 20-day period and spatial variations across more than 150 sampling locations in Europe made it possible to characterize the contaminated air masses. After the Chernobyl accident, only a few measurements of the gaseous (131)I fraction were conducted compared to the number of measurements for the particulate fraction. Several studies had already pointed out the importance of the gaseous (131)I and the large underestimation of the total (131)I airborne activity level, and subsequent calculations of inhalation dose, if neglected. The measurements made across Europe following the releases from the Fukushima NPP reactors have provided a significant amount of new data on the ratio of the gaseous (131)I fraction to total (131)I, both on a spatial scale and its temporal variation. It can be pointed out that during the Fukushima event, the (134)Cs to (137)Cs ratio proved to be different from that observed after the Chernobyl accident. The data set provided in this paper is the most comprehensive survey of the main relevant airborne radionuclides from the Fukushima reactors, measured across Europe. A rough estimate of the total (131)I inventory that has passed over Europe during this period was <1% of the released amount. According to the measurements, airborne activity levels remain of no concern for public health in Europe.

Excitation functions and yields for cyclotron production of radiorhenium via nat W(p,ߙxn)181-186gRe nuclear reactions and tests on the production of 186gRe using enriched 186W

Abstract Excitation functions and thin-target yields for the 181-186gRe radionuclides have been measured by the stacked-foil activation technique on tungsten foils of natural isotopic composition for different proton energies up to 22.0 MeV. A further check on the cross sections was done by irradiation of thick-targets and comparing the irradiated thick-target yields with those calculated by analytical integration from the thin-target yields. The production of 186gRe was also studied by the irradiation of thick-target of enriched 186W with a 13.6±0.2 MeV proton beam. The results for 186W(p,ߙn)186gRe were compared also to those calculated by the EMPIRE II code (version 2.19), due to 186gRe extensive applications in nuclear medicine for metabolic radiotherapy of tumours. It was found that the maximum percentage of 186gRe by irradiation of natural tungsten is about 20% only, which confirms the conclusion that high radionuclidic purity and specific activity of 186gRe necessitate the use of highly enriched 186W target.

Thin-target excitation functions and optimization of simultaneous production of NCA copper-64 and gallium-66,67 by deuteron induced nuclear reactions on a natural zinc target

Copper-64 is a radionuclide suitable for labeling of a wide range of radiopharmaceuticals for PET imaging, as well as systemic or local radioimmunotherapy of tumors. Among the possible methods for cyclotron production of No Carrier Added (NCA) 64Cu (61Cu), we investigated the deuteron irradiation on natural Zn target, via (d,axn) and (d,2pxn) nuclear reactions. This paper reports the preliminary results about the experimental determination and theoretical calculation of thin-target excitation functions in the energy range up to 19 MeV for 61Cu, 64Cu, 66Ga, 67Ga, 65Zn and 69mZn. A fast selective radiochemical separation of NCA 64Cu from Zn target and Ga radionuclides, with quality control tests is described too.

Cyclotron production, radiochemical separation and quality control of platinum radiotracers for toxicological studies

The increasing concentration of Pt, Pd and Rh in the environment is mainly due to the release of these elements from the catalytic converters of the motorvehicles. This situation makes it necessary to carry out metallotoxicological experiments on both cell cultures and laboratory animals, in order to assess their impact on living organisms after a Long Term and Low Level Exposure (LLE). Both nuclear reactionsnatIr(p,xn) andnatOs(α,xn) were investigated in the energy range up to 45 MeV for protons and 38 MeV for alpha-particles, in order to optimize the irradiation parameters for the production of188,189,191Pt. Several sets of thin- and thick-target excitation functions were determined experimentally by cyclotron irradiation at both Milano and Ispra cyclotrons. This paper reports the irradiation parameters studied and adopted and two radiochemical procedures for the separation of radio-Pt from an Os target, as well as from ruthenium, iridium and gold impurities. These procedures were used to obtain very high specific activity Pt radionuclides in No Carrier Added (NCA) form. Radionuclidic, radiochemical and chemical purity measurements were carred out by the use of several techniques like ψ-spectrometry, ion-exchange radio-chromatography, atomic absorption spectrometry and neutron activation analysis.

Irradiation methods for production of high specific activity radionuclides in no carrier added form

High Specific Activity Radio-Nuclides (HSARN) are a powerful tool to label a large range of chemical species at very low concentration levels. In order to obtain these radiotracers in a very high specific activity form, it is necessary to optimize the production methods, to separate and purify them from the irradiated target without the addition of inactive carrier, to carry out a series of analytical and radioanalytical tests to determine their “true” specific activity and to verify a series of purity parameters. A review of irradiation methods and nuclear parameters adopted in our laboratories for the preparation of some tens of radiotracers are presented.

The excitation functions of (100)Mo(p,x)(99)Mo and (100)Mo(p,2n)(99m)Tc.

Proton-induced nuclear reactions for generation of (99)Mo and (99m)Tc radionuclides were investigated using the stacked-foil activation technique on 99.05% enriched (100)Mo targets at energies up to Ep=21MeV. Excitation functions of the reactions (100)Mo(p,x)(99)Mo and (100)Mo(p,2n)(99m)Tc have been measured.

Content of trace elements in the respirable fractions of the air particulate of urban and rural areas monitored by neutron activation analysis

The concentrations (ng/m3) of more than 30 trace elements have been determined in the total air particulate matter and in the sizesegregated fractions collected in urban, industrialized, and rural residential areas in northern Italy by means of a multistage inertial impactor with the PM10 inlet. All measurements have been carried out by instrumental neutron activation analysis, except for Pb and Cd, which have been determined by electrothermal atomic absorption spectroscopy. Analytical quality assurance procedures have been developed with special regard to blanks, reagents, and sampling. Total concentrations and the granulometric distribution found in the different locations are reported and compared.

Excitation functions and yields for cyclotron production of radiorhenium via deuteron irradiation: natW(d,xn)181,182(A+B),183,184(m+g),186gRe nuclear reactions and tests on the production of 186gRe using enriched 186W

Abstract Excitation functions, thin- and thick-target yields for the 181−186gRe and 187W radionuclides were measured by the activation stacked-foil thecnique on natural tungsten foils for deuteron energies up to 18.0 MeV. These cross sections were validated by comparing the experimental results for thick-target yields with those calculated by integration of the thin-target yields. It was found that the maximum 186gRe content by irradiation of natural tungsten is about 55%, a higher value compared with the one found for proton beam, but not sufficient to use natural tungsten for medical purposes yet. Thus, in order to have a higher specific activity AS of 186gRe, the use of enriched 186W target is necessary. Therefore the irradiation of a thick target of enriched 186W by accelerated deuterons was studied and the results for the production of 186gRe were compared with those obtained from the irradiation of the same target by accelerated protons. It was found that the deuteron irradiation is preferable for three reasons: larger yield, less contamination by tantalum radioisotopes and smaller required amount of the target, which simplify the separation of the 186gRe from the target itself.

Application of radiotracers with high specific radioactivity to metallotoxicological studies

The use of radiotracers with high specific activity in research on health impact of trace metals overcomes many of the analytical difficulties associated with experimentation carried out at metal levels which are typical of the polluted environment. It allows one to detect and measure ultratrace amounts of metals in biological samples and to follow them into different biochemical compartments, such as subcellular fractions and molecular components. This work shows typical examples of metallotoxicological studies carried out at the JRC-Ispra using radioisotopes with high specific radiactivity produced in the nuclear reactor and in the cyclotron. Applications refer to the use of45Ti,48V,64Cu,95Nb and106mAg in in-vivo and in-vitro studies related to environmental and occupational toxicology research on trace metals.

Excitation function for deuteron induced nuclear reactions on natural ytterbium for production of high specific activity 177gLu in no-carrier-added form for metabolic radiotherapy

Deuteron-induced nuclear reactions for generation of no-carrier-added Lu radionuclides were investigated using the stacked-foil activation technique on natural Yb targets at energies up to E(d)=18.18 MeV. Excitation functions of the reactions (nat)Yb(d,xn)(169,170,171,172,173,174g,174m,176m,177g)Lu and (nat)Yb(d,pxn)(169,175,177)Yb have been measured, among them three ((169)Lu, (174m)Lu and (176m)Lu) are reported for the first time. The upper limit of the contamination from the long-lived metastable level (177m)Lu was evaluated too. Thick-target yields for all investigated radionuclides are calculated.