Measurement of the energy spectra of delayed neutrons for the isotope-separated, fission product precursors Br-87, Br-88, Br-89, Br-90, I-137, I-138, I-139, and Te-136 are reported for an energy range up to 1213 keV and with lower cutoff energies of 11.1, 11.1, 29.9, 48.9, 14.2, 23.3, 29.9, and 48.9 keV respectively. These data were obtained at the TRISTAN Isotope Separation On-Line facility using H-2 and CH4 gas-filled proportional counters. The data for each of the bromine, iodine, and tellurium isotopes show good qualitative agreement with the published He-3 ionization chamber delta at energies above similar to 200 keV. In addition, they provide definitive spectral information down to their respective cut-off energies.

In prior publications, the authors reported measurements of the energy spectra of delayed neutrons for the isotope-separated fission product precursors {sup 93}Rb, {sup 94}Rb, {sup 95}Rb, {sup 96}Rb, {sup 97}Rb, {sup 143}Cs, {sup 144}Cs, and {sup 145}Cs. Such studies of delayed neutron energy spectra have important applications in reactor physics, primarily relating to the fundamental role played by delayed neutrons in the kinetic behavior of nuclear reactors. Measurement of the energy spectra of delayed neutrons for the isotope-separated, fission product precursors {sup 87}Br, {sup 88}Br, {sup 89}Br, {sup 90}Br, {sup 137}I, {sup 138}I, {sup 139}I, and {sup 136}Te are reported for an energy range up to 1,213 keV and with lower cutoff energies of 11.1, 11.1, 29.9, 48.9, 14.2, 23.3, 29.9, and 48.9 keV, respectively. These data were obtained at the TRISTAN Isotope Separation On-Line facility using H{sub 2} and CH{sub 4} gas-filled proportional counters. The data for each of the bromine, iodine, and tellurium isotopes show good qualitative agreement with the published {sup 3}He ionization chamber data at energies above {approximately}200 keV. In addition, they provide definitive spectral information down to their respective cut-off energies.

The final set of results of “ground-state” β−-branching intensities obtained in a program of systematic study of those regions of the fission-product nuclides accessible to investigation using the 252Cf-based INEL ISOL facility are presented. A total absorption γ-ray spectrometer, operating in a 4πγ-β coincidence mode, was used to obtain these “ground-state” β−-branching intensities; where here the “ground-state” is defined to include all states below a selected γ-ray discriminator level. Results obtained for 89Rb, 90gRb, 91Rb, 93Rb, 93Sr, 94Sr, 94Y, 95Sr, 95Y, 140Cs, 142La, 143Ba, 143La, 144Ba, 144La, 145Ba, 145La, 146Ce, 146Pr, 147Ce, 147Pr, 148Ce, 148Pr, (2.27 min), 149Pr, 149Nd, 151Pr, 151Nd, 152Pm (4.1 min), 153Nd, 155Nd, 157Pm, 157Sm, 158Sm and 158Eu are presented and compared with existing published data.

0.38-mCi{sup 59}Ni source is demonstrated for use in energy dispersive x-ray fluorescence (EDXRF) for the analysis of low levels of chromium contamination in soils. Employing this excitation source, chromium concentrations of 10 ppm were detectable in 1000-s counts using a 30-mm{sup 2} Si(Li) spectrometer.

The utility of the method using a total absorption γ-ray spectrometer system, operating in the 4 πγ-β coincidence mode, to measure ground-state β−-branching intensities of deformed rare-earth fission-product nuclei is discussed. For such nuclei it is demonstrated that, given sufficient information concerning the lower excitation states being populated and their de-excitation modes, precise values can still be obtained for their “ground-state” β−-branching intensities; where here the “ground-state” is defined to include both the true ground state and all excited states below a selected γ-ray discriminator level. Results obtained for 153Nd, 153Pm, 154Nd, 154Pm(1.7 min), 155Pm, 156Pm, 157Pm, 157Sm and 158Sm are presented and compared with existing published data.

A field performance test was conducted at the INEL with the mobile Rapid Transuranic Monitoring Laboratory (RTML) that was developed for the analysis of samples from sites or facilities potentially contaminated with plutonium, other actinides, and γ-ray emitting activation and fission-product radionuclides. The performance test and results are described for the Photon Analysis Spectrometer System (PASS), one of three RTML assay systems. This system consists of a thin-window, n-type Ge spectrometer, that automatically analyzes soil, smear, and air particulate-filter samples for actinides emitting L x rays, and for activation and fission products that emit γ rays. The measurements were blind and performed with 11-g soil samples gathered from the Cold Test Pit and with spiked samples containing known mixtures of239Pu,241Am60Co, and137Cs. In the spiked samples the plutonium activity concentrations ranged from ∼75 to ∼500 pCi/g while the other radionuclides ranged from ∼10 to ∼130 pCi/g. Lower limits of detection (LLDs) were verified to be 1, 5, 5, and 40 pCi/g for241Am,60Co,137Cs, and239Pu, respectively. Results from the performance test are presented.

PASS (Photon Analysis Spectrometer System) is a pulser-equipped, extended range, thin-window, Ge detector spectrometer that is capable of automatically measuring radionuclide activity concentrations in up to 100 samples per day at remediation sites. No operator intervention is required after the counting queue for the sample changer has been setup. Actinides are measured from L X-rays following α decay such as APu → A−4U and 241Am → 237Np and from low-energy γ-rays by spectral component analysis. Activation, fission products and a few actinides (e.g., 241Am) are measured from their characteristic γ-ray emission by fitting the associated peaks. Pulses from a precision, dual-energy pulser can be used to determine the energy scale, provide documentation of the data quality, and provide a correction for pulse pileup. Soil, smear, and air particulate samples can be counted. For an 11-g sample counted for 15 min the lower-limits-of-detection are 50, 1, and 5 pCi/g for plutonium, americium, and several γ-ray emitting radionuclides, respectively.

A total absorption γ-ray spectrometer has been developed on the 252Cf-based INEL ISOL facility and is being used in a program of measurements of β−-decay intensity distributions of short-lived fission-product nuclei. Spectra for 139Cs and 140Cs have been measured and compared with those simulated for the published decay schemes as a test of the completeness and correctness of these schemes. New β−-intensity distributions have been deduced for the decay of these isotopes.

The Portable Isotropic Neutron Spectroscopy (PINS) and Gamma Neutron Assay Technique (GNAT) assay systems that were developed with funding from the office of Research and Development (NN20), were taken to the Stored Waste Examination Pilot Plant (SWEPP) facility at the Radioactive Waste Management Complex (RWMC) and applied to the assay of surrogate and Rocky Flats Plant waste contained in 55-gal drums. PINS, a portable prompt {gamma} neutron activation analysis technique, was able to identify key elements in both the surrogate and real waste so that three-main waste categories: metal, combustible material, and cemented chlorinated sludge wastes could be identified. GNAT, a {gamma}, neutron assay technique for the identification and quantification of fissioning isotopes, was able to identify {sup 240}Pu in surrogate waste in which nine 1-g nuclear accident dosimeters were inserted. GNAT was also able to identify {sup 24O}Pu in real 55-gal waste drums containing 15- and 40-g of plutonium even in the presence of high activity concentrations of {sup 241}Am.

A total absorption gamma-ray spectrometer (TAGS) has been used to measure the summed gamma-ray spectra for several fission products. A Si detector was used to collect beta-particle-gated coincidence TAGS spectra. This system has been used to measure the coincidence spectra for 138–141Cs. The analyses of these spectra are based on response functions for monoenergetic gamma rays and electrons that were computed with a Monte Carlo code. Beta-feeding distributions as a function of the excitation energy of the level have been deduced.

A field test of the Rapid Transuranic Monitoring Laboratory (RTML) developed at the Idaho National Engineering Laboratory (INEL) was conducted as part of a demonstration sponsored by the Buried Waste Integrated Demonstration (BWID). The RTML is a mobile, field- deployable laboratory developed for use at buried radioactive waste remediation sites to allow onsite preparation and analysis of soil, smear, and air filter samples for alpha and gamma-emitting contaminants. Analytical instruments installed in the RTML include an extended range, germanium photon analysis spectrometer with an automatic sample changer, two large-area ionization chamber alpha spectrometers, and four alpha continuous air monitors. The performance of the RTML was tested at the Test Reactor Area and Cold Test Pit near the Radioactive Waste Management Complex at the INEL. Objectives, experimental procedures, and an evaluation of the performance of the RTML are presented.

Prompt gamma neutron activation analysis (PGNAA) has long been employed for chemical analysis in process streams and laboratories. Recent improvements in the design of germanium gamma-ray spectrometers, the miniaturization of their associated components, and the development of [open quotes]powerful[close quotes] notebook personal computers (PCs) permit the design of PGNAA systems for truly portable in-field use. Portable isotopic neutron spectrometry (PINS) (of gamma rays) was developed at the Idaho National Engineering Laboratory for in-field inspection and verification of chemical weapon inventories where a system that can be carried into an area inaccessible by wheeled transport (rough terrain, confined spaces, etc.) and that is capable of operating on battery power is required. PINS is now also finding use outside of military applications.

A total absorption γ-ray spectrometer (TAGS), based on a 25.4 cm diameter × 30.5 cm long NaI(Tl) well detector, has been developed at the INEL on-line isotope separator facility. A Si detector in the well of the NaI(Tl) detector allows one to collect β-particle-gated coincidence spectra as well as singles spectra. With this system, measurements of the total absorption spectra have been made for a number of fission product nuclei. The analysis of the measured spectra is based on response functions for single γ rays that are computed with a Monte Carlo code. Routines have been written to use these response functions to simulate the response to a cascade of several γ rays and by extension to a whole decay scheme. The bremsstrahlung from a ground-state β branch can also be simulated. The quality of the simulation is demonstrated for test spectra of 137Cs, 24Na, 60Co, and 110mAg. As examples of the operation of this system, the measurements and analyses of the β-decay feeding distributions are described for the decay of 141Ba, 139Cs and 140Cs.

A method has been developed to measure ground-state beta--branching intensities with the total absorption gamma-ray spectrometer at the INEL ISOL facility. This spectrometer, which is used to measure beta-feeding (or beta-strength) distributions to excited states in neutron-rich fission-product nuclei, consists of a 25.4 cm diameter x 30.5 cm long well-type NaI(Tl) scintillation detector together with a Si beta- detector located in the collection-tape transport line in the well. With this spectrometer operating in the beta-gamma coincidence mode as a 4-pi-gamma-beta detector, ground-state beta--branching intensities are obtained from simple ratios of beta-gamma coincidence to beta-singles count rates together with additional, generally small, correction terms. Results obtained for Rh-106, Cs-138-141, Ba-141-142, La-142-145 and Ce-145 are presented and compared with existing data obtained with conventional nuclear spectroscopic methods.

A total absorption gamma-ray spectrometer (TAGS), based on a large NaI(Tl) detector, has been developed at the INEL ISOL facility. With this system measurements of total absorption spectra for 138–144Cs, 141,142Ba, 142–145La, and 145Ce have been made. From these spectra we will deduce the beta-decay feeding distributions as a function of the daughter level energy.

A method has been developed to measure ground-state β−-branching intensities with the total absorption γ-ray spectrometer at the INEL ISOL facility. This spectrometer, which is used to measure β-feeding (or β-strength) distributions to excited states in neutron-rich fission-product nuclei, consists of a 25.4 cm diameter × 30.5 cm long well-type NaI(Tl) scintillation detector together with a Si β− detector located in the collection-tape transport line in the well. With this spectrometer operating in the β-γ coincidence mode as a 4πγ−β detector, ground-state β−-branching intensities are obtained from simple ratios of β−γ coincidence to β singles count rates together with additional, generally small, correction terms. Results obtained for 106Rh, 138–141Cs, 141–142Ba, 142–145La and 145Ce are presented and compared with existing data obtained with conventional nuclear spectroscopic methods.

In recent years, the use of the mass separation technique coupled on-line to a source of fission product nuclides has provided a wealth of new information on the nuclear decay properties of such nuclides. In addition to their relevance in basic studies of nuclear properties of neutron-rich nuclei, the fission product nuclides as a group, because of their intimate link with energy production in fission reactors, occupy a unique position in the field of applied nuclear decay data. Further, in addition to their critical role in nuclear reactor technology (decay heat source term, environmental concerns, etc.), such data have important applications in astrophysical calculations involving the rapid neutron capture process (r-process) of elemental synthesis in stellar environments. The scope of the nuclear decay data measurements being undertaken using the Idaho National Engineering Laboratory's (INEL) isotope separation on-line (ISOL) facility is focused on a systematic study of the gross nuclear decay properties of short-lived fission product isotopes, i.e., ground-state half-lives, beta-decay energies and beta-decay feeding (or beta-strength) distributions. In this paper, the authors discuss the results of new measurements of beta-decay energies and feeding distributions.