Routine production of F-18 radionuclide using proton beams accelerated in a cyclotron could potentially generate residual radioisotopes in the cyclotron vicinity which eventually become major safety concerns over radiation exposure to the workers. In this investigation, a typical 11-MeV proton, self-shielded cyclotron has been assessed for its residual radiation sources in the cyclotron's shielding, tank/chamber, cave wall as well as target system. Using a portable gamma ray spectroscopy system, the radiation measurement in the cyclotron environment has been carried out. Experimental results indicate that relatively long-lived radioisotopes such as Mn-54, Zn-65 and Eu-152 are detected in the inner and outer surface of the cyclotron shielding respectively while Mn-54 spectrum is observed around the cyclotron chamber. Weak intensity of Eu-152 radioisotope is again spotted in the inner and outer surface of the cyclotron cave wall. Angular distribution measurement of the Eu-152 shows that the intensity slightly drops with increasing observation angle relative to the proton beam incoming angle. In the target system, gamma rays from Co-56, Mn-52, Co-60, Mn-54, Ag-110 m are identified. TALYS-calculated nuclear cross-section data are used to study the origins of the radioactive by-products.

Detection and measurement of radiation sources around BATAN's cyclotron facilities in Serpong are required as an early step to avoid radiation impacts on the radiation employees who work with the cyclotron. In this paper, radiation emitted from the wall of the CS-30 cyclotron cave are detected and measured using an NaI(Tl) detector coupled with a pocket multichannel analyzer (MCA) at a counting time of 30 minutes for each sampling point on the wall. The sampling points were in the directions of within ±150 o with respect to the incoming proton beams, and the measurements were conducted at heights between 1.2 m and 1.8 m off the floor for every sampling point. The experimental results indicate that Co-60 and Cs-134 detected on the cyclotron cave wall are major radionuclides that contribute to the emitted gamma radiation. The distribution of the gamma ray intensities given off by Co-60 and Cs-134 depend on the angle and position of the sampling points. In general the highest gamma ray rates can be found in the area around 0 o relative to the incoming proton beams. In addition, no other radioactive sources are significantly detected on the wall. The maximum exposure measured on the wall surface was much less than the permissible occupational exposure for radiation workers and general public.

Abstract. The laboratory-scale erosion-corrosion testing facility at BATAN's Center for Radioisotope and Radiopharmaceutical Technology (PTRR) in Serpong was employed to simulate flow-induced corrosion of iron surfaces. Surface loss rates were measured by a nuclear technique called thin layer activation (TLA) analysis. A 10-MeV proton beam generated from a typical CS-30 cyclotron was used to produce 56 Co radionuclide layers on iron surfaces via a 56Fe(p,n) 56 Co nuclear reaction. The labeled iron specimens were then exposed to circulating seawater simulated in BATAN's flow-induced corrosion test facility. The experimental results indicated that the TLA technique was able to measure a very low flow-induced erosion rate of 0.91±0.3 µm/hr. There was no significant difference in the measured surface loss rates between the remaining activity method and the concentration method. The iron surface loss in seawater was lower than that of the same material in HCl solution observed in earlier studies. Keywords:56 Co radionuclide; cyclotron; flow-induced corrosion; nuclear technique; thin layer activation (TLA). IntroductionThin layer activation (TLA) is a nuclear technique previously developed to help measure very low wear and erosion-corrosion rates of industrial components [1][2][3][4][5][6]. It involves target irradiation using a beam of charged particles such as protons, deuterons, He-3 and He-4 or neutrons to directly label the surface of interest (widely called a coupon) with a very thin layer containing radioactive isotopes (a few hundred µm thick). Following the target irradiation, the activated surface layer is exposed to a flowing corrosive fluid. This is eventually followed by measurement of its radioactivity ratio before and after erosion-corrosion takes place. The radioactivity loss is directly proportional to the surface loss and therefore its erosion-corrosion rate can be determined precisely [7]. In order to get information on the surface loss of the coupon specimen, a calibration curve, which represents the relationship between radioactivity ratio and surface loss, must first be prepared by means of either a stacked-foil or an abrasion method [8]. Also, theoretical calibration curves canSeawater Flow-Induced Erosion Rates for Iron using TLA 483 be calculated for a given projectile, beam current, energy, target geometry and irradiation time [8].Two methods have been developed to measure the radioactivity loss of a specimen/coupon, i.e. the remaining activity method and the concentration method. The remaining activity method measures the radioactivity left over in the coupon at a certain time during the erosion-corrosion process and then compares the radioactivity with a calibration curve prepared earlier to obtain the corresponding surface loss. On the other hand, the concentration method detects the specific radioactivity removed from the coupon's surface, after which the same procedures as in the first method are applied.Flow-induced corrosion (sometimes also called erosion-corrosion) of iron-based m...

Radiation safety for patients during positron emission tomography (PET) procedures is affected by the amount of radioactive impurities generated during production of fluorine-18 (18F) radionuclide. In this investigation, the dependence of 18F production yield and radioactive impurities on proton irradiation dose is discussed. Enriched water (H2O18) target was bombarded perpendicularly by 11-MeV proton beams at various proton doses. Experimental results indicated that the 18F radioactivity yield and the amount of 56Co and Ag110m radioactive impurities depend strongly on the proton dose. In the proton dose range between 2 μAhr and 20 μAhr, the radioactive impurities increased with increasing proton dose. There was no significant difference in the radioactivity yield of both 56Co and Ag110m impurities at low proton dose between 2 and 10 μAhr. However a huge difference was recorded when the dose was increased above 10 μAhr. The experimental data can be used to predict the amount of impurities generated during 18F production at proton dose of higher than 20 μAhr.

Ni 57 Co Cyclotron Secondary neutron Nuclear medicine TALYS code 57 Ni and 57 Co radioisotpes are used in the synthesis of radiopharmaceuticals, for research purposes, as well as radiotherapy in nuclear medicine due to its decay characteristics. In this research, 57 Ni and 57 Co were produced using secondary neutrons. The secondary neutrons employed in this investigation were generated by bombarding 11 MeV protons into a target system consisting of Havar  foil as a vacuum window, aluminum foil as an energy degrader, aluminum tube as a target holder and nickel foil as a target via (p,n), (n,n) and (n,2n) nuclear reactions. The TALYS-calculated data were used to understand the origin of the secondary neutrons. In this experiment, variable Ni target thicknesses of 75, 150 and 225 m were irradiated with a fixed proton beam dose of 0.67 Ahr in order to study the dependence of the radioisotope yields on the target thickness. For the first time, 57 Ni and 57 Co radioisotopes were produced and observed experimentally following 58 Ni(n,2n) 57 Ni → 57 Co nuclear reaction. Experimental results indicated that for 225-m thick Ni target, the 57 Ni yield of 10.85 ± 3.29 Ci/Ahr and 57 Co yield of 6.04 ± 2.45Ci/Ahr were recorded after an hour cooling period. The resulted yields did not strongly depend on the target thickness. This proposed novel method is a promising method to obtain higher radioactivity yield in the production of 57 Ni and 57 Co radioisotopes.

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One of the quality control measures in F-18 radionuclide production concerns the impurities which might be present in the proton-irradiated enriched H2 18 O target. In this investigation, proton irradiations of enriched water targets were theoretically simulated by the Stopping and Range of Ions in Matter (SRIM) 2013 codes, followed by experimental measurements. First, the SRIM-calculated data were employed to understand the origins of the recoiled and sputtered species. Using a portable Gamma Ray Spectroscopy System, recoiled and sputtered radioactive impurities were measured in the enriched water target following F-18 production using 11 MeV proton beams. The experimental results indicate that Havar window-originated Co-56 radionuclide and silver body-originated Ag-110m radioisotope were identified in the postirradiated enriched H2 18 O target. In addition, after passing the 18 F solution through a column containing Quaternary Methyl Acetate (QMA) resin, none of the radionuclidic impurities were any longer observed to any great extent in the sample.

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