Study of gas generation in real L/ILW containers

To obtain reliable estimates of the quantities and rates of the gas production in L/ILW a series of measurements was carried in the last 7 years in Hungary. The typical gas production rates were 0.05–0.2 STP litre gas/day for CO₂ and CH₄ generation, and less for H₂. No explosive gas mixture was indicated in the L/ILW drums during the investigated storage period. Compositions of headspace gases in closed L/ILW vaults were in agreement with gas generation processes observed in L/ILW drums. The stable carbon isotope measurements show that the main source of the CO₂ gas is the degradation of organic matter and indicates microbial degradation processes as the main sources of CH₄. Typical tritium activity concentrations were <10 Bq/l gas in the drums and <1,000 Bq/l gas in the vaults. Typical ¹⁴C activity values of the headspace gases were <2.0 Bq/l gas in the drums and <1,000 Bq/l gas in the vaults.