Project title:

Neutron beam optimisation for cancer treatment therapy and materials research

Project goals:

The overall objective of the project is to provide the public, in particular representatives of medicine, industry, research centres and universities, with access to a high quality neutron beam with unique parameters on a global scale. The emerging research station will enable a broad spectrum of basic research in the fields of biomedical engineering, materials and physical sciences, as well as implementation work, which will translate into an increase in the competitiveness of Polish science, industry and, in the future, ensure the improvement of public health.

The research station at the horizontal channel of the MARIA research reactor is located at the level of the reactor core, at a distance of 4 metres from its graphite reflector. The specific location allows for a very intense ionising radiation field, comparable to the radiation levels prevailing at the extremes of the core. Such significant radiation levels are achieved by the apparent shortening of the 4-metre distance through the installation of an intermediate channel and the stationary and rotating beam-closer section of the H2 horizontal channel. The intermediate channel, approximately 1m long and filled with nitrogen, forms the first part of the radiation shield. The second part of the shielding is the beam-closer, consisting of a stationary and a rotating part. The closer, which is approximately 2m long, is constructed of heavy concrete, among other materials.

The installation described leads to a mixed beam of 12 cm diameter with a flux density of 10⁸ thermal neutrons/cm2/s. The design of the closer allows the intensity and energy spectrum to be modified by changing the materials in the moving part of the closer. The final stage of the stand includes the installation of the target material in the front of the intermediate channel.

The beam is routed into the workspace of the H2 neutron irradiation workstation, which is located in the irradiation room. The size of the workspace allows large objects to be positioned and irradiated together with associated apparatus, i.e. control and power supply equipment. The irradiation room provides stable conditions for both the irradiation of biological samples and specialised material samples. The design also makes it possible to bring the facility for testing to a specific atmosphere and temperature. Special conditions are also required for cryogenic tests aimed at fusion work. The workspace of the test stand allows large components and entire devices to be irradiated, even when connected to power. Conducting such tests allows reversible changes in apparatus performance to be tracked in the radiation field, as well as irreversible changes resulting from radiation damage. The research described is important for the development of technologies and materials for Generation IV reactors, measurement techniques and plasma diagnostics of thermofusion systems, as well as all devices and components intended for long-term operation in the high-dose power ionising radiation field. The components studied are dedicated, among others, to medical and industrial accelerators, as well as to systems and devices dedicated to space missions.

The concept and experience gained in the construction of the H2 beam closer are unique on a European scale. The team developing the H2 beam-closer concept has been invited to adapt the concept of a rotating beam-closer in the DONES research infrastructure in Granada. Furthermore, the R&D work performed using the test bed at the H2 horizontal channel of the MARIA reactor will allow the testing of new boron carriers that could bring breakthroughs in the treatment of cancers such as head and neck, brain and disseminated tumours.

The approval of the H2 channel irradiation site for safe use in terms of radiological protection is an iterative process that requires successive measurement campaigns. By achieving the intended effect is meant the dosimetric description of the workstations of the experimenters and the H2 channel maintenance staff. Radiological measurements are planned at the measurement points in the laboratory rooms defined in the calculation model and at the workstations of the experimenters and station attendants. The results of the measurements will be used to determine the exposure of the personnel present at the workstations prior to the installation of the fixed shielding and as validation of the calculation model. The simulation of dose power distribution and dose equivalent power will allow optimising the placement of fixed shields in the irradiation workstation rooms. The MCNP particle transport code with validation data in the form of measurement results will be the tool for planning the deployment and determining the parameters of the radiation shielding.

The work will be carried out successively as the installation of the H2 irradiation station proceeds. The availability of equipment at the contractor's disposal allows flexible adaptation to the work being carried out. The works will be carried out immediately after the steps in the assembly of the H2 irradiation facility and immediately after the installation of the fixed shielding. Activities related to the construction of the irradiation stand also require the preparation of documentation, instructions and permits for the commissioning of the thermal neutron beam stand. All documents, i.e. quality plans, safety reports and one-time instructions, must be created in accordance with the legislation. Any modernisation of a system or a structural or equipment component of a nuclear facility that affects nuclear safety or radiological protection requires the approval of the President of the State Atomic Energy Agency. According to the schedule, the second task is to prepare the documentation necessary to restore the functionality of the beam closer on horizontal channel H2.

Another of the tasks is to realise and install a beam closer for the H2 horizontal channel. The design of the H2 bundle closer was completed this year and submitted for approval. It is assumed that, once approved, the closer components will be fabricated and installed in the channel niche located in the MARIA reactor casings. In order to carry out the installation, it is necessary to prepare procedures and tools that will allow the handling of the containment elements of considerable weight and dimensions (cylindrical disks 60 cm in diameter and weighing 200kg). The installed bundle closer will allow MARIA reactor personnel to be in the laboratory space during reactor operation. In addition to the beam-closer, the project plan includes the construction of a beam catcher, i.e. a mobile biological shield in the H2 irradiation room. The purpose of its construction is to shield the adjacent technical rooms from the radiation of an open beam hitting the wall behind the irradiation facility.

The commissioning of a bench for therapy research, materials research for thermofusion and nuclear programmes, and industrial research also requires beam measurements. As a result of the requirements, the main objective of the task is to develop protocols describing how to verify neutron beam parameters for radiobiological, chemical, medical, materials and industrial research. The uniqueness of the proposed beam is related to the possibility of conducting research in three different neutron energy ranges, as well as with different contributions from the gamma-ray component. Measurements leading to the preparation of protocols will be carried out at three main stages of development, i.e. after the installation of the stationary coils of the H2 channel beam closer, after the installation of the rotating coils and during the installation of further elements modifying the energy spectrum and the contribution of the gamma component to the beam. At each stage of the project, measurements will include phantom studies and studies using passive, active and biological detectors. Commercially available solutions will be used in the research, and new phantoms dedicated to boron-neutron therapy research will be developed.

An advantage of the irradiation stand under construction is the possibility of geometrically shaping the beam by carefully selecting the design of the beam filtering and/or collimating elements. This requires the preparation of detailed geometrical models integrated with the beam-closer model. Another element is the modification of the energy spectrum of the beam. For this purpose, literature studies and neutron transport modelling using a Monte Carlo code will be carried out. The result of the neutron analyses will allow the selection of filter materials to modify the energy spectrum of the beam taking into account the needs for the envisaged experiments.

Programme:
Science for Society
Area:
Science for Innovation
Project leader:
Dr. Michał A. Gryziński, Eng.
Project period:
2022-2024