PNNL

Abstract

The ANSI/HPS N13.1-2011 standard requires gaseous tracer uniformity testing for sampling associated with stacks used in radioactive air emissions. Sulfur hexafluoride (SF6), a greenhouse gas, has long been the gas tracer used in such testing. Due to its high global warming potential, nitrous oxide (N2O) was chosen to reduce the impact of gas tracer tests on the environment. An added benefit to the use of the N2O is that, after initial investments in equipment upgrades, the cost of the gas itself is lower so modest cost savings are realized. Although, in principle, all tracer gases should behave in an identical manner for measuring mixing within a stack, a series of physical tests guided by statistics was performed to demonstrate the equivalence of N2O testing to SF6 testing in the context of these stack qualification tests.