The low-temperature irradiation facility, Tieftemperatur-Bestrahlungsanlage (TTB), at the 4-MW Munich Research Reactor (Forschungsreaktor München — FRM) makes it possible to perform neutron irradiations at liquid helium temperature. Two irradiation positions exhibiting different neutron spectra are available. The possible integration of suitable measuring or transfer cryostats into the liquid helium circuit of the TTB allows the use of this facility for the study of a large variety of neutron irradiation effects in basic research as well as in materials sciences. Besides a description of the general experimental setup, some topics of current TTB research are briefly summarized.