GB984240A - Improvements in or relating to radiation monitors - Google Patents

Abstract

984,240. Radio-active liquid monitoring. UNITED KINGDOM ATOMIC ENERGY AUTHORITY. May 1, 1963 [May 10, 1962], No. 17937/62. Heading G1A. Apparatus for measuring alpha radiation from a liquid 7 comprises an alpha radiation monitor 1 and a cell for the liquid, characterized in that a protective film 20 is interposed between the liquid and an alpha radiation detecting screen 19 of the monitor to prevent liquid droplets being deposited on and thus contaminating the detecting screen 19. In the arrangement shown the liquid flows into the apparatus through a pipe 8 and a separator 4 removes undesirable material from the liquid which then flows into a flat cell 2 through an air-bubble trap formed by a bar 28 an underflow weir 29 and a cowl 30. Laminar flow of the liquid across the cell 2 is achieved by a V-notched weir 5 at the outlet end of the cell. Alpha radiation from the liquid is detected by a zinc sulphide screen 19 deposited on a light guide which couples the screen to a photomultiplier 39. The protective film 20 consists of a P.T.F.E. strip fed from a drum 21 to a take up drum 22 and when the area of P.T.F.E. across the face of the screen 19 has become contaminated a motor (not shown) is used to drive the drum 22 and bring a new area of P.T.F.E. across the screen 19. For calibration a standard alpha source on a plate (not shown) is remotely controlled to move between the liquid 7 and the screen 19. Condensation on the P.T.F.E. strip, the screen 19 or the standard source from the air is prevented by heating the incoming air by an electrical heater 26.