Abstract: An arrangement for protecting an integrated circuit device (11) against latch up during a nuclear event comprising a capacitance (15) and a switch (17) connected in parallel across the power supply lines (13) of the device. When the power supply lines are connected to a power supply (19) the capacitance stores energy sufficient to supply necessary operating currents to the device during its normal operation. The switch is arranged so that, under a transient gamma pulse incident thereon during a nuclear event, its impedance is set to a low value at such a rate that the energy stored by the capacitance is discharged through the switch and the voltage applied to the device via the power supply lines is pulled down to such a level and at such a rate as to prevent transient gamma pulse induced latch-up in the device.

Abstract: An arrangement for protecting selected devices of an electronic equipment from radiation, e.g. resulting from a nuclear event, including a timing circuit (13) responsive to the output of a radiation sensing device (11) first to operate a first switch (35a) to isolate a power supply rail for the devices from the power supply to the equipment when the radiation level exceeds a predetermined level, and then to operate a second switch (35b) to ground the supply rail, thereby shunting to ground residual stored energy in devices connected to the rail.