An Example of Remote Maintenance in High Radiation Fields

Abstract

Six auxiliary low pressure small (diameter < 5.0 cm) pipes located inside the reactor vault of the Douglas Point Nuclear Generating Station (DPNGS) had failed due to fretting wear at U-bolt supports: two had worn through the wall and developed leaks, the others had worn > 50% through the pipe hall. Human entry into the vault was not possible because of high radiation fields (300-3000 rad/h (3-30 Gy/h), under best reactor conditions), hence hands-on repair was not possible. The pipes were repaired and resupported to prevent further fretting wear failures during February-September, 1980. The repair work was performed using custom designed and developed remotely operated tooling and close circuit TV viewing. Three main groups were involved in the repair work: Atomic Energy of Canada Engineering Company (AECEC)--the reactor owner; Ontario Hydro--the reactor operator; and, Chalk River Nuclear Laboratories (CRNL). In this report, the contributions made by CRNL are summarized and discussed. An overview of the overall repair job is given in Ref. [1]. The contributions of the other groups are summarized in Ref. [2].