Challenge
Bluegrass first widened the bottom half of the circular equipment hatch by approximately 6’ to provide clearance for the reactor vessel. The hatch was 10.5’ thick with 16 horizontal and vertical layers of #18 reinforcing steel and a steel liner one inch thick. The majority of the charging floor, a portion of the refueling canal and one side of the reactor cavity walls were concrete and required removal. The 6’ thick refuel canal was cut into pieces weighing 40,000 lbs. The reactor cavity wall ranged from 3.5’ to 5’ thick and was removed in 40 sections each weighing approximately 30,000 lbs.
The final challenge was precision cutting 6 reactor nozzles and safe ends to meet the tight tolerances of the reactor cask fit. The nozzles, with a 54” outside diameter and walls 15” thick, were clad with stainless on the inside surface. The safe ends were 3” thick with a 23” diameter. Because using water to cool the diamond wire was prohibited, Bluegrass instead employed a system of spraying atomized liquid CO2 onto the wire which kept the wire cool and cleared of metal shavings.
Completed ahead of schedule, with worker exposure rates well under estimates, the nozzle cutting proved diamond wire technology is a key tool in nuclear decommissioning.