An implantable medical apparatus comprises a solid state electronic circuit, an ionizing radiation exposure sensor, an ionizing radiation dose rate sensor, and a controller circuit. The ionizing radiation exposure sensor is configured to detect an exposure of the solid state electronic circuit to ionizing radiation, and generate an indication of a non-single-event-upset (non-SEU) effect to the solid state electronic circuit from the exposure to ionizing radiation, wherein the sensor comprises an accumulated ionizing radiation exposure sensor. The controller circuit is configured to blank the indication from the accumulated ionizing radiation exposure sensor when the radiation dose rate sensor indicates that flux ionizing radiation exceeds a flux ionizing radiation threshold.