3ele2 Time-rate of Arrival of Active Aerosols Information desired is: in the ducts. a. Rate of increase of activity level of the air moving b. Time at which the activity per unit volume in the ducts is at a maximum. ce Proportionality of increase and decrease of activity per unit volume at each sampling station within the same duct. ad. Presence or absence,and amount of redistribution, of e,. Variation of gamma intensity with time as measured activity once deposited on duct walls. outside the exhaust and intake stack. Items a, b, ¢ and d will be obtained by installing a series of air samplersatvarious locations in the boiler and ventilation ductwork as shown in Tab F+2, The air~sampler head is a long diverging tube protruding through a duct elbow and extending sufficiently far upstream of the clbow that the latter will not influence the air stream at the opening of the tube. LBuct air will be drawn iso—kinetically into the tube, slowed by the divergence of the tube and pulled through a continuously moving strip of filter paper by a positive displacement pump. The diameter of the tube will be small compared to the diameter of the duct. Since the pump will displace a constant number of cubic fcet per minute and since the filter paper will move from one roll to another at a constant speed, the activity on the paper should be directly proportional to the activity per unit volume of air traveling through the duct at any time. counting. The filter paper rolls will be shipped to USNRDL for They will be driven through a cowmter attached to a recording rate meter producing a record of count-rate against time, Parts of the filter may be analyzed radiochemically to obtain the proportions of the major isotopes contributing to the observed count~rate; whereupon, the count-rate data may be calibrated against a standard filter impregnated with norm amounts of the predominantly occurring isotopes in the correct proportions. ; ST, LOUIS FRC Item e will be obtained by use of gamma time-intensity recorders described in Annex F, By proper location and selective shielding, these instruments will be used to determine the magnitude of gamma radiation as a function of time,emitted by specific arrangements such as boiler air intake and boiler. Results will be compared with those of unshielded gamma intensity-time recorders installed in spaces to measure the intansity of the total gamma field as a function of time at the point of mcasurement. lb ee 73