10 CFR §36.37

1. (a)If electrical power at a panoramic irradiator is lost for longer than 10 seconds, the sources must automatically return to the shielded position.
2. (b)The lock on the door of the radiation room of a panoramic irradiator may not be deactivated by a power failure.
3. (c)During a power failure, the area of any irradiator where sources are located may be entered only when using an operable and calibrated radiation survey meter.