Development of a tomographic instrument for gamma-ray nondestructive assay

Conference · Sun Aug 01 04:00:00 EDT 1993

OSTI ID:10178375

Prettyman, T H; Estep, R J; Sheppard, G A

The most widely used Transmission-corrected gamma-ray nondestructive assay (NDA) instruments is the Segmented Gamma Scanner (SGS) that was developed by the Los Alamos Nuclear Safeguards program in the early 1970s to determine the radioisotopic content of waste. SGS assays are accurate for low-density samples and also for high-density samples that are known to be uniform and homogeneous. However, for dense, heterogeneous samples, substantial bias is observed in SGS assays. To assay heterogeneous samples, knowledge of the distribution of emitting and attenuating materials is required. As a result we are developing a tomographic instrument to assay samples for which the assumptions of the SGS analysis are grossly violated. This instrument, known as the Tomographic Gamma Scanner (TGS), has the same basic components as the SGS, including a HPGE detector, a transmission source, and a mechanism to rotate and elevate the sample. However, an additional mechanical motion has been added that allows the detector to move in the direction transverse to the sample axis. This additional motion in combination with more stringent detector collimation enables the TGS to acquire, three-dimensional transmission and emission tomographic projection data from which the distributions of emitting and attenuating material can be determined. This spatial information provides a detailed correction for sample heterogeneities that results in more accurate assays. Our work on the development of the TGS has emphasized the role of the TGS as an NA instrument. Accurate determination of the quantity of emitting material is the primary goal. Precise determination of the distribution of emitting materials is a secondary and potentially conflicting objective. Consequently, desip considerations and analysis techniques differ from those of computerized tomography applied to medicine and nondestructive testing. An experimental TGS has been used to assay 208-{ell} drums containing plutonium.

• Research Organization: Los Alamos National Lab., NM (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 10178375
• Report Number(s): LA-UR--93-2580; CONF-931160--12; ON: DE93018551
• Country of Publication: United States
• Language: English

Related Subjects

054000
055001
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
440103
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL PROTECTION
CONTAINERS
GAMMA DETECTION
GAMMA RADIOGRAPHY
GAMMA SOURCES
HEALTH AND SAFETY
HIGH-PURITY GE DETECTORS
IMAGE SCANNERS
NONDESTRUCTIVE ANALYSIS
NUCLEAR SPECTROSCOPIC INSTRUMENTATION
PERFORMANCE TESTING
PHOTON COMPUTED TOMOGRAPHY
PLUTONIUM
RADIOACTIVE WASTE STORAGE
RADIOACTIVE WASTES
SAFEGUARDS
TECHNICAL ASPECTS