Provide a nuclear reactor power monitoring technology for enhancing the monitoring accuracy and reliability in nuclear thermal hydraulic stability. The input pulse width of an input signal is adjusted to an output pulse width of an output signal based upon a recording control signal for control of recording on a storage medium. Alternatively, the cover plate may include a peripheral rim projecting away from the sprinkler head. The beams emitted by the laser diodes in the first direction are collimated and deflected at different angles and are separated thereby. A slave oscillator path may be used to select time signals generated in a sibling chip, whereby the master oscillator path is deselected.