Cleanup of tritiated water in typical reactor-size concrete enclosures is simulated taking into account the soaking of the tritiated water into the concrete. For an enclosure made of concrete with ordinary porosity, the “soaking effect” has little effect on the cleanup time for releases with tritium concentrations of <1 × 108 Bq/m3. If the concrete porosity is reduced to 0.03, the soaking effect has little effect on the cleanup time for a tritium concentration of up to 1 × 109 Bq/m3. An optimum flow rate of between 1 × 104 and 1.5 × 104 m3/h for the tritium removal system minimizes the costs of removal system equipment and facility downtime for releases with a concentration >5 × 108 Bq/m3 in a typical reactor-size enclosure. Estimated total costs to complete the cleanup within 48 and 72 h with these flow rates are within 1.3 times of the minimum total costs. The estimated total costs for a cleanup time of 48 h are comparable to those for a cleanup time of 72 h.