[en] HIP-TEDDI is a computer code package for the calculation of nuclear quantities in experiments or experiment positions and data relevant for the operation of the materials testing reactor HFR at Petten. It is based upon the calculation of the neutron flux densities in four broad energy groups, in X, Y geometry, averaged over the fuel height. From these flux densities and from-pre-calculated fine group spectra in several core regions, various nuclear quantities are derived such as fast flux densities (E > 0.1 MeV and E > 1.0 MeV), equivalent fission neutron flux density, 2200 m/s flux density, damaging flux densities, damage-to-activation ratio (DAR), equivalent DIDO nickel flux density and the nuclear heating rate. After each burn-up step the corresponding fluences, displacements per atom (DPA) and burn-up averaged DAR are determined. For the operation of the reactor a number of important data are calculated such as over reactivity, control rod insertion depth, shut-down time margin and thermal safety data e.g. allowable maximum inlet temperature of primary water. Calculations are performed at start-up with initial concentration of fission products, at start-up with equilibrium concentration of rapidly saturing fission products and after each burn-up step for the actual concentration of fission products. For all these situations the control rod setting is taken into account. Information about the history of the fuel elements is produced for subsequent HIP-TEDDI runs and for fuel transport and administration programmes. The HIP-TEDDI package consists of a number of computer programmes written in FORTRAN IV. The data transmission between these programmes takes place by means of files which are temporarily stored at backbround memory. The programme operates on the CDC 6600 computer at Petten. A complete calculation for one cycle of 26 days, with 15 copies for the experimentators and the operation staff, needs a field length of 60 K (decimal) words, a central processor time of about 300s and an input/output time of about 100 s