  We argue that storage rings can be used for the detection of low-frequency
gravitational-wave background. We explain the systematic shrinkage of the
machine circumference of the storage ring of the SPring-8, observed by Takao
and Shimada (Proceedings of EPAC 2000, Vienna, 2000, p.1572), by the influence
of the relic gravitational-wave background. We show that the systematic
shrinkage of the machine circumference can be explained by a relic
gravitational-wave background even if it is treated as a stochastic system
incoming on the plane of the machine circumference from all quarters of the
Universe. We show that the rate of the systematic shrinkage of the machine
circumference does not depend on the radius of the storage ring and it should
be universal for storage rings with any radius.
