Radionuclide production

The PRISMAP production facilities provide radionuclides (“radioisotopes”) to be used at user labs or PRISMAP medical facilities. The production process involves usually multiple steps, in the following called “unit operations”, depending on the radionuclide in question and the quality required for a given application.

Radionuclides are mainly produced by irradiation of stable targets with neutrons or charged particles. The result of such irradiation is not a directly usable radionuclide, but just an activated target material that has to undergo further chemical or physical separation/purification steps before final use.

For each production facility, a detailed information sheet is available by clicking on its box.

Operational details are provided below.

Operational details

Within PRISMAP, neutron irradiations are performed at the high-flux reactors RHF (ILL), BR2 (SCK CEN) and MARIA (NCBJ) while smaller radionuclide inventories can be produced at the spallation neutron source SINQ (PSI).

Proton irradiations at different energies are performed at the cyclotrons at Hevesy laboratory, NCBJ, ARRONAX and PSI. At MEDICIS relativistic protons (> 1 GeV) are used to induce spallation reactions. Alpha irradiations can be performed at ARRONAX. For specific cases, deuteron irradiations may be used at Hevesy laboratory or ARRONAX.

Targets to be irradiated in high flux reactors are always solid or gaseous, not liquid. Accelerator targets may also be liquid, but for the radionuclides considered within PRISMAP, they will dominantly be solid. Since the end user usually requires the radionuclides in liquid form, a minimal dissolution of the target material is required after irradiation. This is e. g. the case for reactor produced radionuclides in carrier-added (c.a.) quality.

To obtain radionuclides in non-carrier-added quality (n.c.a.), a quantitative removal of the target material is required, i. e. an additional radiochemical or physical unit operation. This radiochemical separation is particularly challenging for chemically similar lanthanides.

In certain cases, utmost isotopic purity can be achieved by chemical means alone, namely for accelerator irradiations with low-energy projectiles (e. g. 44Sc, 64Cu, 211At), by the “indirect” production route in neutron irradiations (e. g. 47Sc, 111Ag, 161Tb) or by “milking” generators (e. g. 225Ac from 229Th). For other cases, a physical separation method may be required, namely mass separation, performed at MEDICIS with in-house activated spallation targets or with imported targets that have been activated by neutrons or protons at other PRISMAP facilities.

The radiochemical separations for different radionuclides are performed at ARRONAX, Hevesy laboratory, NCBJ or PSI, either from targets activated at in-house facilities or from targets that have been activated at other PRISMAP facilities. Moreover, JRC Karlsruhe performs radiochemical separations of 225Ac from 229Th generators, because a prior neutron irradiation to produce the precursor of the long-lived 229Th generator isotope has been performed in the past already.

Notably in every case the last unit operation (characterisation) requires an appropriate analytical laboratory with equipment for radionuclides speciation (e. g. gamma-ray spectrometry). This explains why an accelerator or reactor alone cannot supply any radionuclides to the end user. The end user will receive the characterised product always from a radiochemical laboratory, which may either be located on the same site as the accelerator or reactor or elsewhere at a different PRISMAP partner.

Availability and constraints

Due to the strongly differing complexity of the separation process, the availability of different radionuclides differs accordingly. For example, 64Cu can be provided regularly (every week) by ARRONAX or DTU. Another extreme would be the production of n.c.a. 169Er or 175Yb, which involves one high flux reactor, MEDICIS for the mass separation and one radiochemistry lab for a radiochemical purification and characterisation. Production of such radionuclides requires long-term advance planning to coordinate the involved facilities and can only be performed less frequently.

Similarly, the maximum batch activities differ considerably. For reactor radionuclides like 161Tb batch activities over 100 GBq can be envisaged while batch activities at accelerators are generally lower. ARRONAX would for example produce about 15 GBq 64Cu per batch. The activity of mass-separated samples is mainly limited by the mass separator, typically leading to batch activities <1 GBq, but further development will improve efficiency and throughput of the mass separation process and allow to raise the batch activities over time.

For now, the radionuclide portfolio is made available Over the duration of the project additional radionuclide products and qualities are foreseen to be added to this portfolio.