Experimental and Numerical Simulation of Radiolysis Gas Detonations and Mechanical Response of BWR Exhaust Pipes

Radiolysis gas (2H₂+O₂) can accumulate in BWR steam piping in case of steam condensation. An ensuing detonation of the radiolysis gas is the likeliest cause of a pipe and/or valve damage. In the current work we investigate a typical BWR exhaust pipe, which connects the high pressure steam piping with the ambient atmosphere, under the following “worst case” scenario: (a) accumulation of radiolysis gas in an exhaust pipe, (b) fast valve opening to the high pressure system with steam at 70 bar, and (c) adiabatic pressurization of the radiolysis gas by the steam. Taking into account a water surface level of 6 m from the open end this leads to an equilibrium state of 20 bar pressure and 602 K temperature for the pressurized radiolysis gas. The main purpose of the current work was an experimental and numerical evaluation of the maximum pressure load and the integrity of the BWR exhaust pipe in case of a detonation of the pressurized radiolysis gas.