Selective measurement of short-lived fission products in a gas flow

Claim 1

DEVICE FOR SELECTIVELY MEASURING THE AMOUNT OF SHORT-LIVED FISSION PRODUCTS IN A GAS FLOW COMPRISING, IN COMBINATION, A DECAY PRECHAMBER, A DETECTION CHAMBER DISPOSED DOWNSTREAM SAID PRECHAMBER, DUCT MEANS FOR CIRCULATING AT LEAST A PORTION OF SAID GAS FLOW SUCCESSIVELY THROUGH SAID DECAY PRECHAMBER AND SAID DETECTION CHAMBER, DETECTING MEANS FOR DETERMINING THE RADIOACTIVITY IN SAID DETECTION CHAMBER, ION COLLECTING THE RADIOACTIVITY IN TRATING, WHEN ENERGIZED, IONS IN A PARTICULAR AREA OF SAID DETECTION CHAMBER, VALVE MEANS FOR PREVENTING, WHEN ENERGIZED, THE CIRCULATION OF SAID GAS FLOW THROUGH SAID CHAMBER, CONTROL MEANS FOR ENGERGIZING SIMULTANEOUSLY SAID ION COLLECTING MEANS AND SAID VALVE MEANS, AND COMPARISON MEANS FOR COMPARING THE DETERMINATION OF SID DETECTING MEANS BEFORE AND AFTER THE OPERATION OF SAID CONTROL MEANS, SAID COMPARISON MEANS COMPRISING A FIRST AND A SECOND TRIODE EACH INCLUDING ONE CATHODE GROUNDED THROUGH A RESISTOR, SAID CATHODES BEING CONNECTED THROUGH AN APPARATUS ADAPTED TO INDICATE THE POTENGIAO DIFFERENCE THEREBETWEEN, WHEREAS THE GRIDS ARE CONNECTED THROUGH A