This section is responsible for the operation, maintenance and development of the meson production target facilities, as well as for the development and scientific support of the spallation source targets of SINQ and UCN. It also fulfills important tasks in the process of radioactive waste disposal from the accelerator facilities and carries out activation and shielding calculations.
The meson production target facilities encompass the two graphite target wheels E and M, the collimator system between Target E and SINQ and the beamdump behind Target E. Due to interactions with the highly energetic proton beam, the power deposition in these components is very large. This gives rise to special design requirements. To ensure an efficient and safe operation we constantly monitor the functionality of the system and make necessary improvements. The picture shows a Target E insert.
To install and remove beam line components from the proton channel, the secondary beam lines and at UCN we have several shielded exchange flasks at our disposal. We are responsible for their use, operation and maintenance as well as for new designs if the need arises. The picture shows the target E exchange flask during operation in the proton channel. It can also be used for the exchange of other beam line components like, for example, collimators.
The targets of the spallation sources SINQ and UCN were developed in our section. Based on our Monte Carlo and Finite Element simulations, the design of the SINQ solid state target was optimized further over the past few years. The picture shows part of an MCNPX model for SINQ target 10. We perform neutronic calculations and investigate in detail the cooling as well as the thermomechanical characteristics of the target rods (e.g. using ANSYS). An online monitoring system is being developed to detect possible failures at an early stage. In addition, work is going on for a new design of the moderator system to increase the neutron flux and to adapt the neutron energy spectrum better to the instruments. For this purpose MCNPX simulations coupled to McStas are performed.
Our section serves as contact and coordination centre for the disposal of radioactive waste from the accelerator facilities. We manage and check the application forms for disposal, offer assistance with completion of these forms. During the filling of the waste containers we calculate the nuclide inventory, record waste container data in the data bank ISRAM and provide concepts for the disposal of special waste forms as well as waste type specifications for the authorities. In addition, we estimate for the authorities the future volume and total activity of the waste, which will eventually end up in the final repository, when the facility is put out of service in the future. For the radioactive waste disposal we collaborate closely with the personal of the service cell for radioactive components (ATEC), with the radioprotection group (SU) and with the section RBE of PSI, which carries the overall responsiblity for the disposal of radioactive waste. The picture shows a filled waste container.
We calculate nuclide inventories and dose rates of activated materials for the overall radiation protection planning during dismanteling or maintenance work, as well as for the disposal of radioactive waste. Due to the high proton energy and thereby induced spallation reactions, a very broad spectrum of nuclides is produced. The picture displays an excerpt of the chart of nuclides; Co-60 is a typical dose relevant nuclide.
Shielding calculations are required for the protection of persons against direct radioactive radiation from the proton accelerator facilities (biological shielding), the protection of persons against remanent gamma radiation of activated components (e.g., by using exchange flasks and shielded containers), as well as the protection of electronic devices against direct radiation. The picture depicts part of the shielding construction for the proton therapy facility PROSCAN.