The POSEIDON project activities between March 2024 and February 2025 are summarized. Monte Carlo simulations show the clear advanta-ge of large CZT detectors compared to the presently used small detectors for PGET of spent nuclear fuel was demonstrated: the efficiency to detect the full energy of the gamma rays from the decay of 137Cs is more than 20 times larger. This justifies the further development of the large CZT detec-tors. The results of a first measurement campaign combining a tomogra-phic setup at Uppsala University with a detector from IDEAS in Oslo and a collimator from HIP in Helsinki demonstrates the feasibility of PGET measurements using state-of-the-art large position-sensitive CZT detec-tors, showing that such detectors are a viable choice for future develop-ment of the PGET method. This experimental work is being complemen-ted with Monte Carlo simulation of PGET of real spent nuclear fuel. First results, using a somewhat simplified gamma ray emission source, de-monstrate that the Monte Carlo framework performs well. A measurement campaign using two commercial gamma ray imagers, the CZT-based H420 and the germanium-based GeGI, in a realistic nuclear waste setup at Svafo and a real-life decommissioning situation at TSL, has resulted in valuable practical experience with both imagers. The conclusion is that both imagers perform similarly, with the H420 being somewhat easier to handle and operate. The activities have increased knowledge and exper-tise in the Northern Countries on several topics related to gamma ray imaging. A brief outlook of the continuing activities over the next year is presented.