Project leader: Teemu Siiskonen  Personnel

The RAD3S project investigates and develops new measurement and analysis methods, produces basic physical data, and uses computational methods to foster radiation and nuclear safety, security, and safeguards (3S). A major part of the work is done in collaboration with the Finnish Radiation and Nuclear Safety Authority (STUK).

Medical applications and dosimetry: External beam radiotherapy using heavy particles (protons, heavy ions or neutrons) has gained popularity in recent years. The well-defined range of particles (compared to photons) has benefits such as enabling conformal dose distributions and potentially reducing the dose deposited in healthy tissues near to the target treatment volume. Today, one of the largest uncertainties in proton and heavy ion beam dosimetry comes from the stopping power uncertainties and, subsequently, from the particle range. The RAD3S project will develop novel measurement methods to determine the stopping powers of protons and ¹²C ions in liquid water. The challenge of developing a water target of uniform thickness for the measurements in vacuum will be tackled during 2023 and beam time for the actual measurement will be applied for in Autumn. In addition, new detector technologies will be investigated for beam profile quality assurance measurements. This work is a continuation of the MPMIB project that was funded by the Academy of Finland. In the MPMIB project a position-sensitive Si photon counting detector with spectroscopic capabilities was developed. In 2023 gaseous position-sensitive detectors will be investigated, also for application in BNCT (Boron Neutron Capture Therapy).

The investigation of radiation doses from patient imaging during the radiotherapy treatment will continue in 2023. Here, the focus is on Monte Carlo simulations and machine learning methods to determine patient organ doses in real patient anatomy.

Radiation detection: Detector systems currently used for environmental surveillance and radiation safety often rely on rather rudimentary and simple radiation detection techniques. In most applications only one type of radiation is measured and usually in singles mode with simple one-dimensional histogram analysis. The main goals of the projects carried out here are to bring state-of-the-art detection technologies and multi-parameter data-acquisition techniques to routine use in safety, security and safeguards applications. The work to be carried out in RAD3S is a continuation of the previous HIP RADSAFE and STUK/JYU RADICAL projects. The main themes and developments are based on: multi-detector setups and coincidence techniques, Monte-Carlo simulations, multi-parameter digital data acquisition systems, standardized list-mode data format and tailor-made data sorting and analysis algorithms.

In 2020-2022 the capability of the PANDA (Particles and Non-Destructive Analysis) system was expanded and is now capable of coincident alpha, beta and gamma-ray spectroscopy. In 2023, the next steps will be to implement conversion electron spectroscopy and to upgrade the data acquisition system.

A second major goal is the completion of investigation and development of application-specific detectors for full-body counting. Work carried out in 2020-2022 has resulted in the development of a simulation package including a computational phantom and benchmarking the simulations with data from real-world measurements. Optimized detection geometries have been investigated using the simulation package. In 2023 it is planned to perform tests of the detector capabilities with a view to reducing the minimum detectable activity and/or measurement times.

In addition, several new projects relying on novel detectors with positional and directional sensitivity to radiation are either started or in the planning stage with funding applications being submitted. Most of the applications are related to emergency preparedness, for example monitoring the radiation level in foodstuffs or in atmospheric samples.

Passive Gamma Emission Tomography of spent nuclear fuel: The development of Passive Gamma Emission Tomography of spent nuclear fuel (and eventually other nuclear waste items) will be continued, aimed at a better understanding of the PGET method as well as the development of an improved design.

Regular measurement campaigns at the Finnish nuclear power plants will continue, with the measurements being designed such that they contribute to a better understanding. We plan to focus on optimizing the gamma ray energy windows and the careful selection of small, 0.5 degree, angular steps. The GOSSER agreement between HIP and STUK under which these activities take place will be extended to the end of 2023. Also, a sustained effort in Serpent2 simulations for improved understanding of the PGET method will be performed. Capitalizing on the PGET data set by sharing it under a collaboration agreement with selected partners. We will follow up on such collaborations with Uppsala University and University of Illinois & Heriot-Watt University. The aim is to co-author peer reviewed papers.

A collaborative student project that was started in autumn 2022 at Uppsala will be concluded. The student(s) will use the processed measurement data from spent nuclear fuel, such as the reconstructed pin-wise activity from PGET and PNAR ratios to evaluate to what extent machine learning algorithms can be applied to learn more about the fuel assemblies. The POSEIDON project, a collaboration with Uppsala University and funded by NKS-R, started in June 2022 and will continue until May 2023. It investigates the usefulness of large position-sensitive semiconductor detectors in PGET via GEANT4 simulations. The simulations will be verified by measurements with the GeGI device at the Detector Laboratory. If the 1-year extension that has been applied for is honoured, the project will run until May 2024. In this extension, the postdoc hired will spend 6 months at Uppsala University for extensive measurements using the GeGI device of HIP and a segmented germanium detector of Uppsala with radioactive sources, including the mock-up spent fuel source assembly Bettan at Uppsala.

Gamma ray imaging for BNCT: A programme to develop gamma ray imaging for boron neutron capture therapy (BNCT) will be investigated. Interested partners so far are HUS/HY, Neutron Therapeutics, JYFL, the Department of Mathematics and Statistics at HY.

Collaboration: The stopping power measurements will be carried out JYFL-ACCLAB, the Accelerator laboratory of University of Jyväskylä (H. Kettunen). Collaboration with the Aarhus proton therapy clinic (L. Stolarczyk) is established for the proton beam quality control measurements. Patient dose simulations and BNCT beam measurement development are done in collaboration with the EURADOS network (P. Ferrari, H. Brkic, P. Teles, F. Becker, Z. Jovanovic, L. Stolarczyk, P. Olko), Tampere University Hospital (J. Ojala, M. Nadhum) and Helsinki University Central Hospital (T. Seppälä). The PGET development is done in collaboration with Uppsala University. Gamma ray imaging for BNCT is developed together with HUCH/UH, Neutron Therapeutics, University of Jyväskylä and the Department of Mathematics and Statistics at UH.