We describe a complex for gas-mixture preparation which ensures safe operat
ion of high-activity (up to 100 kCi) gaseous tritium in regular laboratory
environment. The system is designed to prepare a mixture of a given isotopi
c composition with a contamination level of 10(-7) vol fractions for impuri
ties with Z > 1, deliver it to the target, and withdraw it after the work i
s completed. The system was used in experiments on muon-catalyzed fusion wi
th liquid and high-pressure tritium targets. The operating pressure ranged
from 0.1 to 120 MPa; the temperature varied between 20 and 800 K. Gaseous t
ritium of similar to 10-100-kCi activity was used in the experiments. The s
ystem operated reliably, and the tritium volume content in the working area
and the exhaust-ventilation system was below background.