The differential gamma scattering spectroscopy technique is a novel means of nondestructive testing using Compton scattering to determine local density perturbations in a test sample. The test sample is irradiated with a narrow collimated beam of gamma rays, and the scattered radiation field is detected in a transversely placed high- purity germanium detector. The detector provides excellent energy resolution so that a detailed energy spectrum can be obtained. Using the relationship between the scattering angle and the scattering energy that characterizes Compton scattering, the single-scattered spectrum can be used to determine the location of scattering and, consequently, the density distribution along the portion of the primary beam path that passes through the sample. An attractive feature of this technique that sets it apart from other Compton scattering techniques is the ability to detect flaws both on and off the primary beam path.

44458 Anghaie, S.; Humphries, L.L.; Diaz, N.J. Material characterization and flaw detection, sizing, and location by the differential gamma scattering spectroscopy technique. Part I1: experiment Nuc lea r Techno logy , Vol. 91, No. 3, pp. 376-387 (Sep. 1990)

The differential gamma scattering spectroscopy technique is a novel means of nondestructive testing using Compton scattering to determine local density perturbations in a test sample. A series of experiments was conducted to assess the sensitivity of the detection system for different sizes and shapes of flaws located throughout the sample. The results of these experiments are analyzed.

44444 Allen, A.J.; Coleman, C.F.; Conchie, S.J.; Smith, F.A. Application of positron annihilation to the monitoring of fatigue damage and creep in technological components S y m p o s i u m on N o n d e s t r u c t i v e M o n i t o r i n g of Mate r i a l s Proper t ies , Bos ton , Massachuse t t s ( U n i t e d Sta tes) , 28-30 Nov. 1988. pp. 131-142. E d i t e d by J. H o l b r o o k and J. Buss ie re M R S (1989)

This paper reviews the use of positron annihilatitJn methods for technological applications, particularly the use of positron annihilation gamma ray lineshape analysis for the non-destructive assessment of static deformation, machining processes, high cycle fatigue and creep in metal and alloy components. The paper includes description of a transportable lineshape analysis system recently developed for field applications.

44200 Schlieper, G.; Hummert, K.; Arnhold, V.; Dirkes, H. A new instrument for quality assurance in the production of ceramics C e r a m i c F o r u m I n t e r n a t i o n a l , Vol. 67, No. 1-2, pp. 11-15 ( J an . -Feb . 1990)

A nondestructive measuring instrument called the Gamma densomat has been developed to determine the porosity of pressed and sintered ceramic bodies. It measures the absorption of gamma radiation in solids using gravimetric techniques. The theory of gravimetric tests is explained and the design of the device discussed. It is linked to a dedicated computer for data analysis. It is hoped that application of gamma-ray gravimetry to the ceramic production process will give product quality control a boost.

44179 Maninskas, A.L; Kavalyauskas, R.A.; Semenov, Y. V.; Sidaravichyus, I.- D.B. Some aspects of application of electroradiography in high energy ionising radiation Technica l D iagnos t i c s and Nondes t ruc t i ve Test ing, Vol. 1, No. 2, pp. 104-107 ( A p r . - J u n . 1989)

The authors examine the problems of development and application of electroradiographic sheets (ERS) for high-energy ionising radiation with quantum energies of 0.3-0.6 MeV using radioactive sources cesium- 137, iridium-192 and also small betatrons, MIB-4, MIB-4M and PMB-6. Investiga- tions were carried out into the radiographic sensitivity and resolving power in relation to the thickness of the selenium layer of ERS. The dependence of the radiation and radiographic sensitivity on the thickness of the screening (enhancing) lead screen is discussed. Technical data for PERP-3-P sheets are used and it is shown that when using these sources of ionising radiation on PERP-3-P sheets it is also possible to irradiate steel with a thickness of 10-220 ram. Radiographic sensitivity is not lower than that of RT-1 radiographic film without the screen.

43716 Whynot, T.; Hussein, E.M.A. Examination of concrete structures using compton scattering Nondes t ruc t i ve Tes t ing and E v a l u a t i o n for Manufac tu r ing and Cons t ruc t ion . E d i t e d by H . L . M . dos Reis . pp. 285-298. H e m i s p h e r e Publ i sh ing C o r p o r a t i o n , (1990). ISBN 0-89116-926-1

This paper describes the underlying principles of Compton scattering and the implications concerned with distinguishing steel and void from concrete. The detection capabilities of the method is demonstrated using Monte Carlo Simulations and confirmed with laboratory experiments.

43198 Jackson, C.N. Industrial radiography Wes t inghouse H a n f o r d Co . , R i ch l and , Wash ing ton , (Un i t ed Sta tes) , D E 8 9 0 1 0 0 9 7 / G A R , 7pp. (Sep. 1988)

Westinghouse Hartford obtains a wide range of high-quality radiographs in support of its nuclear program. We emphasize safety in all of our work. Safe operation of both x-ray machines and radioactive isotope sources is of primary importance. This effort has paid off; no injuries have been caused by

radiography. As safety techniques have been perfected, they have been shared with the rest of the technical community. This is accomplished by the participation of Westinghouse Hanford personnel on national committees and by publishing findings, such as the need for periodic x-ray of the source tubes. X-ray safety and general safety conditions are emphasized in the control documentation, training, equipment design, and more importantly in the operation of the x-ray and gamma ray devices.

43192 Morgan, 1.L.; Crane, R.M.; Keeley, F. Photon backscatter imaging devices for NDT inspection of offshore TLP riser, tendons, and other subsea components Proceed ings of the Twen t i e th A n n u a l Of f shore T e c h n o l o g y Con- ference , H o u s t o n , Texas ( U S A ) , 2-5 May 1988. Vol. 4, pp. 513-517

The technique of computerized photon tomography offers promise as a fundamentally new method for solving many of the nondestructive testing (NDT) problems encountered in the petroleum industry. An overview of tomographic principles is presented as well as a discussion of recent developments in backscatter techniques that promise to enhance the utility of the method in the unique applications encountered by the offshore industry. The development of a workable NDT system is well within present capabilities and awaits only the design of appropriate deployment hardware for both subsea and surface inspection. Such devices would allow a high degree of precision in determining the structural integrity of critical components throughout their design life.

42963 Abdul-Majif, S.; Dawood, U. Neutron-capture gamma-ray technique for scale identification inside pipes Desa l ina t ion , Vol. 75, No. 1-3, pp. 199-210 (Nov. 1989)

In this technique neutrons from a neutron source such as 241Am - 9Be are allowed to interact with the pipe material. Some of these neutrons are absorbed by the scale materials or by pipe material. Immediately after absorption they will emit gamma-ray photons which are characteristics of the materials. Their intensity will be proportional to the amount of scale while their energy will indicate the type of elements of the scale. Pure Ge gamma detector with multichannel analyzer can be used for measuring the energy and intensity of these photons. By using this technique it was possible to identify CaSO 4, and other deposits.

42810 Sattler, F.J. Improving plant maintenance via nondestructive testing Chemica l Eng inee r i ng , Vol. 96, No. 12, pp. 115-123 (Dec. 1989)

A wide range of nondestructive testing (NDT) techniques can be used to advantage for plant building and maintenance in the chemical process industries. Discontinuities in construction materials, variations in thickness for pipework, faulty welds and problems with heat exchanger surfaces can all be dealt with by correct use of the appropriate NDT technique. The author describes the many applications of NDT to specific problem areas.

42807 Hoddinott, D. Inspecting the Harwell reactors A t o m , No. 399, pp. 10-15 (Jan. 1990)

This article outline the the protocol of safety inspections of the United Kingdom Atomic Energy Authority's reactors Dido and Pluto at Harwell laboratory. The nuclear installations made a number of recommendations in its safety audit of these thirty years old reactors, which are used as neutron sources, for neutron beam studies and fc, r isotope production. The organisation and management of the inspection is described. Not only the reactors themselves, but also the surrounding concrete blocks and steelwork, were subject to a variety of nondestructive testing techniques. The tests were completed with satisfactory results within the timcscale anoted.

42753 Toshiba Radiographic process and appts, with arranged shielding irradiation from two positons-sources and two-dimensional images obtd. by electrical processing E u r o p e a n Pa ten t No. 330,244 (30 Aug . 1989)

42680 Hussein, M.A.; Whynot, T.M. A Compton scattering method for inspecting concrete structures Nuc lea r I n s t r u m e n t s and M e t h o d s in Physics R e s e a r c h , Vol. A283, No. 1, pp. 100-106 (1989)

The feasibility of a Compton scattering technique for the inspection of extended concrete structures for the presence of steel rebar and void enclosures is demonstrated experimentally and by Monte Carlo simulations. A parametric study is performed which identifies the source energy and Compton scattering angle as the most dominant variables affecting the technique. A simple optimization method is, subsequently, developed to aid in the determination of the most appropriate source-detector arrangement for a given depth of concrete.

42670 Clarke, E. T. Cobalt-60 radiography of concrete Mater ia l s Eva lua t i on , Vol. 47, No. 10, pp. 1200-1203 (Oct . 1989)

This paper represents an effort to quantify the variables involved in the cobalt-60 radiography of ordinary concrete and also to determine the performance of fluorescent screens on the film relative to the performance of standard lead screens. Ultimate results are presented in the form of technique charts for practical application.

1 52 N DT & E International June 1 991