In order to carry out x‐ray observations of magnetohydrodynamic wave activity of the plasma during DD and DT (deuterium‐beam‐heated deuterium and tritium plasmas, respectively) operation of the Tokamak Fusion Test Reactor (TFTR), we will need detectors not susceptible to nuclear radiation damage. We have investigated the use of gridded ionization chambers as fast nondamageable x‐ray detectors. A prototype chamber is described which was tested on the PDX tokamak. These tests and laboratory tests with a pulsed x‐ray source suggest that the detector has sufficient sensitivity and speed for the required measurements.