Pulsed neutron generated prompt gamma emission measurement system for surface defect detection and analysis
AssigneeWestinghouse Electric Corp.
InventorMichael D. Heibel
Life of this patent
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Abstract
A method of determining structural defects in a component that utilizes neutron activation of a solution having the ability to penetrate small cracks on the surface of a material via capillary absorption that produces a discernable prompt gamma release of a defined energy when exposed to a neutron pulse. The intensity of the gamma rays produced at the desired energy at a user controlled position on the surface is used to determine the crack location, length and depth.
Claims20
A method of nondestructively detecting a structural defect in a surface of an irradiated material comprising the steps of:
- applying a mixture of a noncorrosive crack penetrant including chemical species that have relatively large cross-sections for fast neutron induced prompt gamma emission interactions of a defined energy to the surface of the material to be examined;
- irradiating the surface of the material with a neutron pulse generator;
- positioning a plurality of beta radiation detectors tuned to the defined energy of photo-electrically produced electrons generated in an electron generating window located between an active region of the detector and the surface being examined, in a regular pattern over the surface of the material to which the mixture is applied, the plurality of beta radiation detectors respectively providing an output indicative of a reception of the prompt gamma release of the defined energy in an area of the surface viewed by a corresponding one of the beta radiation detectors;
- and
- employing the receptions to map a characteristic of the defect.
Apparatus for nondestructively detecting and characterizing flaws in the surface of an irradiated material comprising;
- a spray system configured to spray a mixture of a noncorrosive crack penetrant either having a high Nitrogen content, or one that is mixed with a chemical species having a large portion of an isotope that has a relatively large fast neutron prompt capture gamma emission cross section of a defined energy of photoelectric to the surface of the material to be examined;
- a neutron pulse generator configured to irradiate a surface of the material;
- a plurality of beta radiation detectors, tuned to the defined energy of photo-electrically produced electron energy generated in an electron generating window located between an active region of the beta radiation detectors and the surface being examined, the beta radiation detectors positioned in a predetermined pattern over the surface of the material to which the mixture is applied, the plurality of beta radiation detectors respectively providing an output indicative of a reception of the prompt gamma release of the defined energy in an area of the surface viewed by a corresponding one of the beta radiation detectors;
- and
- a beta radiation detector output from which the receptions can be employed to map a characteristic of the defect.
Dependencies are inferred from the claim text.