A Multipurpose Inertial Electrostatic Confinement Fusion for Medical Isotopes Productions

摘要

A practical onsite breeder of medical radionuclide emitters, gamma and particles, is most wanted for clinical centers and researches. There are many cases where the cost of certain radioisotopes is too high for their introduction on a commercial scale even though the isotopes might have great benefits for society. The medical radioisotopes such as radiotracers PET (Positron Emission Tomography), Tachnetium-99m, Iodine-131, and Lutetium-177 are valuable in their applications but costly in some degrees. Upon experimental and theoretical assessments these radioisotopes can be practically breeded by a single inertial electrostatic confinement IEC fusion compact chamber operated with two ions injectors. The PET radiotracers are usually produced by medical ion accelerator whereas Technetium-99m is usually produced in fission reactors. Typically, hospitals receive molybdenum-99 isotope container, the isotope decays to Tc-99m with half-life time 2.75 days.A 66-kW GET hydrogen ion injector, 75-keV protons beam with 880 mA, is recently designed and under development by Guangdong Provincial Strategic Alliance. This suggests that for when the ion injector is conducted to IEC the projected D/D fusion yield is equal to 1.5 x 109 n/s with central cathode grid voltage and current -75 kV at 1.2 mTorr IEC pressure with ion confinement time 34 sec. The corresponding fusion yields for D/T and D/He-3 are 2.4 × 10~(11) neutrons/s and 3.8 × 10~(10) protons/s, respectively. A multipurpose device for medical isotopes production is under study to reach to high ion confinement time 100 sec.In IEC, a typical proton current is lower than ion accelerator; however the deficit radiation activity is compensated by increasing the thickness of the target, due to the high energy of the emitted protons which is well above the peak energy, and the enrichment of the parent nuclides. The neutrons flux from IEC is projected to be two orders of magnitudes lesser than the thermal neutron flux at the irradiation facilities of fission reactors. However, the deficit of the mass activity from IEC is neutralized by irradiating 98Mo at the resonance region since the resonance integral microscopic cross section is two orders of magnitude higher than the thermal microscopic cross section. Thus it can be said the net activity from both fission reactors and IEC is evened.