Compact instrumentation to apply XRD to residual stress measurement in the field, and non-destructively is available commercially. However, these instruments are restricted to deployment in pipes 100 mm. and larger in diameter or other configurations of similar size, e. g., two parallel surfaces spaced 100 mm. apart.

Penn State University in partnership with HyperNex and funded by EPRI have been investigating the feasibility of developing a miniature XRD instrument capable of measuring stresses in confinements as small as 50 mm. The investigation has centered around using either an isotope or a miniature, low power x-ray tube as the source of x-rays, and an x-ray detector based upon fiber optics. The x-ray detector is fundamentally a Ruud-Barrett Position Sensitive Scintillation Detector (PSSD) using a Charge Coupled Device (CCD) to generate an electrical signal. The miniaturization and geometrical configuration of both the x-ray tube and the fiber optics of the

R-B PSSD have been major challenges.

This paper will describe and discuss the results of the investigation, focusing upon the x-ray sources and detector design.