Quantum mechanics consideration, supported by a concrete example, yielded
standard sources of direct voltage measured by frequency (which is the most
accurate measurable physical quantity) and extremely sensitive instrument
for measuring magnetic induction SQUID (which is an acronym based on the
term Superconducting Quantum Interference Device). The possibility of these
measurements is based on the Josephson junction. In this paper, the
influence of gamma radiation on the measurement uncertainty Type A, of a
commercial Josephson compound, is investigated. The conclusion is that both
dynamic gamma radiation and the dose of gamma radiation, under the
conditions of the experiment, have a negligible effect on the measurement
uncertainty of the Josephson junction. Based on the obtained result, it was
concluded that in the primary metrological conditions, the measurement
uncertainty type A of the Josephson junction is negligible, i. e., that the
secondary cosmic radiation does not affect the standard of the DC voltage
source.