Upgrades improve Diablo Canyon's waste gas sampling system

This article describes how, with increased reliability, the redesigned waste gas sampling system has reduced the equipment's maintenance costs and enhanced plant safety. Hydrogen is added to the reactor coolant in pressurized water reactors (PWRs) to scavenge oxygen. The dissolved hydrogen in the reactor coolant evolves from the solution during storage and processing. This gas collects in tanks and vessels used for storage and processing of reactor coolant. In order to preclude the intrusion of oxygen into these vessels, which could lead to formation of an explosive mixture, an inert gas blanket is maintained at a slightly positive pressure