PGE says the problem is not a risk but needs to be fixed
– By Linton Levy –
According to a report in the San Luis Obispo Tribune, operators at Diablo Canyon nuclear power plant will soon realign a control rod that is hanging too low in one of the plant’s two reactors. The repair will take place in mid-May, when the reactor will be running at reduced power to perform other previously planned maintenance, said Bill Guldemond, the plant’s director of site services.
Each nuclear reactor is equipped with control rods made of neutron-absorbing material. These are raised and lowered into the reactor to control the nuclear fission process. When the rods are fully withdrawn, the reactor is operating at peak power. Conversely, when the rods are fully inserted, nuclear reactions stop and the unit shuts down. Debris is preventing one rod from being fully withdrawn, and it is suspended three inches lower than the others. This misalignment is so slight that it is not affecting the reactor’s operation, Guldemond said.
There is also no reason to believe that the misaligned rod would not drop if the reactor had to be shut down quickly during an emergency, he said. “The configuration of the reactor is completely within limits and technical specifications,” he said. “Fixing this is very important, but it’s not an undue risk.”
The problem was discovered in January when engineers were doing a routine examination. PGE outlined its repair plans to the federal Nuclear Regulatory Commission in a letter sent in February. Engineers plan to fix the problem during the scheduled slowdown by moving the rod back and forth to dislodge the debris. Moving the rods around in this fashion is a standard maintenance activity performed during refueling outages, Guldemond said.