A double diffracting x‐ray spectrometer has been developed which will be used to study the crystallographic features of irradiated materials. The design features of this instrument include: (1) a mechanism to support and align the x‐ray tube as it rotates on a conventional goniometer; (2) a remotely controlled sample holder to position and rotate radioactive samples; (3) a mechanism to adjust the position of a curved aluminum crystal which is placed in the second diffracting position in such a way that it focuses the diffracted x‐rays into the detector; and (4) sufficient lead shielding between the sample and detector to absorb the radiation emanating from the sample in order that such radiation will not influence the detector. Preliminary tests of the instrument have shown that the design features reduce the background radiation originating from the sample to a very low level, and that no serious loss in diffracted x‐ray intensities results from the double‐crystal arrangement.