 Solution

For six hours of operation at the maximum stated carbon-dioxide-equivalent flow, the daily input volume and untreated radioactive activity inventory areFor the three-hour guaranteed delay, every element of the incoming stream acquires the same radioactive decay factor. The radioactive activity released per operating day, attributing the delayed tail to its production day, isEven on the conservative assumption of operation on all $365$ days,so the annual discharge is below the supplied $10^{12}$ Bq limit. For $250$ operating days it is $4.279\times 10^{11}$ Bq. This sums radioactive activity inventories discharged over the year; it does not credit radioactive decay in the environment after release. It also retains the final delayed gas after production stops, rather than bypassing the retention system to empty it.

The residence-time qualification matters numerically. A single tank filled for six hours and released immediately, with radioactive decay during filling but no later hold, would containRepeating that operation on $250$ days releases $1.625\times 10^{13}$ Bq, above the limit. A well-mixed or fill-and-dump system therefore cannot inherit the plug-flow compliance result just because its nominal volume divided by flow equals the selected delay time. The total nitrogen flow and any unretained radioactive carbon species must also be included in a real measured release account.