Nuclear safety, security and safeguards are ways to manage the risks connected to the use of nuclear technology. They should ensure that nuclear materials are not diverted to non-peaceful activities through appropriate safeguards measurements and treaties. They should also prevent the unauthorized possession or use of nuclear materials through security measures and ensure that the material use do not cause harm to people or environment through safety. The Nuclear Physics Division at KTH conducts research on nuclear safeguards and nuclear security with support from the Swedish Radiation Safety Authority (SSM) and the Swedish Research Council (VR) with the objective to develop new detection techniques and methodologies in these two fields and to come up with novel solutions and strategies for enhanced performance. We have developed a new technique based on detection of fast neutrons and -rays from special nuclear materials (SNM, e.g. plutonium) to aid in the careful characterization of radioactive waste that is required before it goes into permanent storage. Computational simulations are crucial to investigate and optimize the detection systems under development, to benchmark the codes by comparing with experimental measurements. To this end, Monte Carlo-based codes are used to perform the radiation transport calculations. Due to the complex geometries and the shielding of waste containing nuclear materials, as well as the large number of simulations needed, a very large computational capacity is needed. We therefore propose to use the computational resource at SNIC to perform these calculations.