Westinghouse Electric Corporation

Richard C Smith

John Bartko

Arnold H Fero

Norman P Goldstein

Ira E Kanter

Disclosed is a method and apparatus for measuring the burnup of nuclear fuel. A curve giving the calculated relationship between the fast neutron emission rate and the burnup of fuel is prepared. The fast neutron counting rate from a sample of nuclear fuel of known burnup is measured and the proportionality ratio between that measurement and the fast neutron emission given by the curve for the same burnup is determined. The fast neutron counting rate of nuclear fuel of unknown burnup is then measured and multiplied by the proportionality ratio to determine the fast neutron emission rate, from which the unknown burnup is then determined by means of the curve.

Measuring nuclear fuel burnup

Alpha particles emitted from radon 220, a daughter product formed from the decay of thorium, are prevented from reaching an alpha particle detector by enclosing the detector in a volume into which alpha-emitting radioactive gases can only enter through a semipermeable membrane at least about 10 mg/cm.sup.2 in thickness. The enclosed volume must be between 30 and 2000 cm.sup.3 and the (AP)/(VL) ratio must be between 10.sup.-7 and 10.sup.-5. Also, the detector must be positioned so as to expose it to gas from the membrane for a distance of at least 2 cm through a solid angle of at least one steradian.

Exclusion of alpha particles from thoron in uranium detection

A neutron activation probe comprises a pulsed neutron source in series with a plurality of delayed neutron detectors for measuring radioactivity in a well borehole together with a NaI (T1) counter for measuring the high energy 2.62 MeV gamma line from thorium. The neutron source emits neutrons which produce fission in uranium and thorium in the ore body and the delayed neutron detectors measure the delayed neutrons produced from such fission while the NaI (Tl) counter measures the 2.62 MeV gamma line from the undisturbed thorium in the ore body. The signal from the NaI (T1) counter is processed and subtracted from the signal from the delayed neutron detectors with the result being indicative of the amount of uranium present in the ore body.

Neutron activation probe for measuring the presence of uranium in ore

The content of uranium, in a solution, as extracted from uranium ore by a solution mining technique for example, is determined by measuring the intensity of selected gamma or X radiation emitted by the solution. The gamma or X radiation is preferably derived from the thorium-234 daughter of uranium 238. The radiation from the solution impinges on a scintillator after being passed successively through K-edge filter foils of an alloy of ytterbium (e.g. with tin), an alloy of lutecium (e.g. with tin), and an alloy of hafnium (e.g. with zirconium). The resulting scintillation counts of the scintillator with the filter foils are arithmetically processed so that the scintillation derived from the thorium-234 63 KeV line is isolated. This scintillation is evaluated as a measure of the uranium content. To assure that the uranium thorium conversion has reached a stable state, the measurement should be made about three months after the uranium solution is produced.

Growing community of inventors

O'Hara Township, PA, United States of America

Richard C Smith