USE OF THE MODIFIED LIGHT DUTY UTILITY ARM TO PERFORM NUCLEAR WASTE CLEANUP OF UNDERGROUND WASTE STORAGE TANKS AT OAK RIDGE NATIONAL LABORATORY

Abstract

The Modified Light Duty Utility Arm (MLDUA) is a selectable seven or eight degree-of-freedom robot arm with a 16.5 ft (5.03 m) reach and a payload capacity of 200 lb. (90.72 kg). The utility arm is controlled in either joystick-based telerobotic mode or auto sequence robotics mode. The MLDUA deployment system deploys the utility arm vertically into underground radioactive waste storage tanks located at Oak Ridge National Laboratory. These tanks are constructed of gunite material and consist of two 25 ft (7.62 m) diameter tanks in the North Tank Farm and six 50 ft (15.24 m) diameter tanks in the South Tank Farm. After deployment inside a tank, the utility arm reaches and grasps the confined sluicing end effecter (CSEE) which is attached to the hose management arm (HMA). The utility arm positions the CSEE within the tank to allow the HMA to sluice the tank's liquid and solid waste from the tank. The MLDUA is used to deploy the characterization end effecter (CEE) and gunite scarifying end effecter (GSEE) into the tank. The CEE is used to survey the tank wall's radiation levels and the physical condition of the walls. The GSEE is used to scarify the tank walls with high-pressure water to remove the wall scale buildup and a thin layer of gunite which reduces the radioactive contamination that is embedded into the gunite walls. The MLDUA is also used to support waste sampling and wall core-sampling operations. Other tools that have been developed for use by the MLDUA include a pipe-plugging end effecter, pipe-cutting end effecter, and pipe-cleaning end effecter. Washington University developed advance robotics path control algorithms for use in the tanks. The MLDUA was first deployed in June 1997 and has operated continuously since then. Operational experience in the first four tanks remediated is presented in this paper.