Since in ITER the radiation field will be much more severe than in present day devices, research programmes are being pursued at JET to develop radiation hard diagnostics and related components. As a preliminary and complementary activity, significant efforts are being devoted to determine the radiation field of both the plasma and the environment with better accuracy. New developments in MCNP calculations and dedicated measurements are providing useful information about the radiation field in the Torus Hall, even during non-operational periods. The effect of Be, which is going to be extensively used in the near future for JET first wall, is being assessed. New materials for activation samples are being considered and tested to improve the calibration of the neutron diagnostics. The long term goal of this work is to obtain spectrometric information by a suitable combination of different materials. Several studies are under way to modify the radiation field using LiH and pure water as neutron filters, to alleviate the problem of the background in the γ-ray measurements. A suite of radiation hard detectors for neutrons, magnetic field and charged particles are being developed. Super-heated fluid detectors, used for yield and imaging, are being upgraded, in order to provide a broad-band spectrometric capability. Chemical Vapour Deposited diamond diodes are being qualified as counters and as spectrometers. Prototypes of Hall probes made of InSb have already been installed on the machine and have provided some preliminary results, whereas Si-on-insulator detectors for the Neutral Particle Analysers are being tested on the bench. Some attention is being devoted to optical components, fibres and mirrors, and to more radiation hard electronics using reconfigurable Field Programmable Gate Arrays.