An experimental superconducting magnetic-monopole detector has been constructed similar to that used by Cabrera. It has been tested for spurious signals by immersing it in a high-radiation environment. No spurious events which could be mistaken for a monopole event occurred. The radiation dose of our experiment was equivalent to 1500× the total neutron dose experienced by the Cabrera experiment due to sealevel cosmic rays during its 151-day lifetime. © 1983 The American Physical Society.