This document establishes specific criteria for the periodic testing required to ensure operational availability of protection systems utilizing the capability called for in the following sections of the Criteria for Nuclear Power Genera ting Station Protection Systems@ IEEE Std 279-1971: Capability for Sensor Checks (IEEE Std 279-1971@ paragraph 4.9). Means shall be provided for checking@ with a high degree of confidence@ the operational availability of each system input sensor during reactor operation. This may be accomplished in various ways@ for example@ one of the following: (1) By perturbing the monitored variable (2) Within the constraints of Paragraph 4.11@ [of IEEE Std 279-1971] by introducing and varying@ as appropriate@ a substitute input to the sensor of the same nature as the measured variable (3) By cross checking between outputs of channels that bear a known relationship to each other and that have read-outs available. Capability for Test and Calibration (IEEE Std 279-1971@ paragraph 4.10). Capability shall be provided for testing and calibrating channels@ and the devices used to derive the 7 final system output signal from the various channel signals. For those parts of the system where the required interval between testing will be less than the normal time between generating station shutdowns@ there shall be capability for testing during power operation.