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Evaluation of well-type Ge(Li) detectors for low-level radiochemical analysis

Description: Well-type Ge(Li) detectors have been evaluated for low-level gamma-ray spectrometry and radiochemical analyses. The detectors were found to have good resolution, high peak-to-Compton ratios and low backgrounds. The use of an anticoincidence shield further improves the detector performance. The detector efficiencies and backgrounds are compared with those obtained with other Ge(Li) detector systems. The well detectors were found to have better detection efficiencies and as low backgrounds as either large coaxial detectors or opposed detector systems. Sum-coincidence effects are more pronounced in the well detector and use of this feature is discussed. Applications which utilize the low-energy response of the detector are described. Minimum detectable activity levels were determined for several nuclides.
Date: September 1, 1977
Creator: Brauer, F. P. & Mitzlaff, W. A.
Partner: UNT Libraries Government Documents Department

Automated krypton-85 gamma ray stack monitor

Description: A Ge(Li) ..gamma..-ray detector, housed in a lead cave, was used in conjunction with a six-liter pressurized (60 psia) well spectroscopy cell to selectively detect /sup 85/Kr stack emissions. This system was calibrated so as to relate the 514 keV ..gamma..-ray counting rate to /sup 85/Kr concentration. Counting rate, or concentration, was continuously recorded using a count rate meter/strip chart recorder combination and was also time averaged over 15 minute intervals using a programmable multi-channel analyzer system with cassette readout. Being completely automated, this ..gamma..-analysis system required little more than liquid nitrogen service and data record retrieval throughout a four-month long sampling period. The sensitivity of this ..gamma..-ray analytical system was such as to achieve a minimum detectable /sup 85/Kr stack concentration of 2 ..mu..Ci/m/sup 3/ for 15 minute counting intervals.
Date: September 1, 1980
Creator: Goles, R.W. & Brauer, F.P.
Partner: UNT Libraries Government Documents Department

Multiplicity and correlated energy of gamma rays emitted in the spontaneous fission of Californium-252

Description: An array of eight high-speed plastic scintillation detectors has been used to infer a mathematical model for the emission multipliciy of prompt gammas in the spontaneous fission of /sup 252/Cf. Exceptional time resolution and coincidence capability permitted the separation of gammas from fast neutrons over a flight path of approximately 10 cm. About 20 different distribution models were tested. The average energy of the prompt gammas is inversely related to the number emitted; however, this inverse relationship is not strong and the total gamma energy does increase with increasing gamma number. An extension of the experiment incorporated a lithium-drifted germanium gamma spectrometer that resolved nearly 100 discrete gammas associated with fission. Of these gammas, some were preferentially associated with fission in which few gammas were emitted. Certain others were more frequent when many gammas were emitted. Results are presented.
Date: June 1, 1982
Creator: Brunson, G.S. Jr.
Partner: UNT Libraries Government Documents Department

Computer-controlled on-line gamma analysis for krypton-85

Description: /sup 85/Kr will be evolved from spent nuclear fuel during both the voloxidation and dissolution processes, so a reliable method for on-line analysis of /sup 85/Kr in the off-gas system is needed. Tritium, /sup 14/C, and /sup 129/I were trapped, and the activity of /sup 85/Kr was then measured using a Li-drifted Ge detector. Equipment used to carry out this analysis is described; the PET computer is used. The /sup 85/Kr evolution rate was correlated with the fuel dissolution rate; the close correlation permits one to monitor the fuel dissolution process. 11 figures. (DLC)
Date: March 1, 1980
Creator: Canuette, R.P.
Partner: UNT Libraries Government Documents Department

Analytical laboratories method No. 4017 - the radiometric nondestructive analysis of Uranium-235 in uranium tetrafluoride

Description: This method permits the nondestructive measurement of U-235 in uranium tetrafluoride (UF/sub 4/) using a Ge(Li) gamma spectrometer. The method was evaluated for UF/sub 4/ in the 0.20 to 1.25 wt% U-235 concentration range, but it could be easily extended to higher U-235 concentrations by using the appropriate standard. A nondestructive U-235 measurement can be performed in about 20 minutes. No measurement interferences have been observed.
Date: January 27, 1987
Partner: UNT Libraries Government Documents Department

Determination of light elements in amalgam restorations. [Dental amalgam]

Description: Rutherford backscattering has been used to measure the major elemental compositions in the near-surface regions of freshly prepared and used samples of dental amalgam. A depletion from bulk stoichiometry of the major elements, which indicates an accumulation of lighter elements on the surface of the materials, has been observed. Increases in the F, Na, Cl, P, O, C, and N concentrations between freshly prepared samples and used samples were measured by observation of gamma rays produced by proton and deuteron induced reactions.
Date: January 1, 1982
Creator: Hanson, A.L.; Jones, K.W.; Kraner, H.W.; Osborne, J.W. & Nelson, G.V.
Partner: UNT Libraries Government Documents Department

Basic studies of a gas-jet-coupled ion source for on-line isotope separation

Description: A hollow-cathode ion source was used in a gas-jet-coupled configuration to produce ion beams of fission products transported to it from a /sup 252/Cf fission source. Solid aerosols of NaCl and Ag were used effectively as activity carriers in the gas-jet system. Flat-plate skimmers provided an effective coupling of the ion source to the gas jet. Ge(Li) spectrometric measurements of the activity deposited on an ion-beam collector relative to that deposited on a pre-skimmer collector were used to obtain separation efficiencies ranging from 0.1% to > 1% for Sr, Y, Tc, Te, Cs, Ba, Ce, Pr, Nd and Sm. The use of CCl/sub 4/ as a support gas resulted in a significant enhancement of the alkaline-earth and rare-earth separation efficiencies.
Date: January 1, 1980
Creator: Anderl, R.A.; Novick, V.J. & Greenwood, R.C.
Partner: UNT Libraries Government Documents Department

Feasibility study for use of a germanium detector in the LOFT gamma-ray densitometer

Description: The primary aim of this study is to predict the performance of a gamma-ray densitometer system using computer modeling techniques. The system consists of a collimated /sup 137/Cs source, a pipe containing a variable amount of water absorber, and a shielded and collimated germanium detector system. The gamma-ray energy spectrum (number of photon counts as a function of energy) has been computed for several sources at the detector. The response for combined sourceconfigurations has been obtained by linear superposition. The signal essentially consists of the counts in an energy window centered on the /sup 137/Cs source at 662 keV that originate from this source. The noise is the background counts in the signal energy window that originate from /sup 16/N scatter radiation and direct and shield tank activation gammas. The detector signal has been computed for 0, 50, and 100 percent water in the pipe. (WHK)
Date: April 27, 1976
Creator: Swierkowski, S. P.
Partner: UNT Libraries Government Documents Department

High rate spectroscopy for on-line nuclear coal analyzer (Nucoalyzer)

Description: A high count rate, time-variant Ge(Li) spectrometer has been developed for on-line coal analysis. The analyzer is being fabricated for use in a power generating station. Prompt neutron activation of coal samples is the basis of analysis, with /sup 252/Cf as the source for irradiation. The spectroscopy system allows counting rates up to 150 k counts per second without significant loss in energy resolution or peak shape. The high data throughput allows the coal analyzer to be used for on-line process control. The coal analyzer will be discussed, with emphasis on the high-rate signal processing system. Results of analysis of coal samples will be presented.
Date: January 1, 1980
Creator: McQuaid, J.H.; Brown, D.R.; Gozani, T. & Bozorgmanesh, H.
Partner: UNT Libraries Government Documents Department

Discrepancies in estimates of plutonium levels in soils by different analytical methodologies

Description: A statistically significant discrepancy was found in estimates of plutonium concentrations in a data set of 23 samples where plutonium has been estimated by both Pu/Am ratios and by direct plutonium analysis. Plutonium concentrations derived from Pu/Am ratios average 13% higher than concentrations obtained from chemical analysis. A possible explanation is a change in /sup 241/Am Ge(Li) methodology between the two relevant data sets.
Date: January 1980
Creator: Kinnison, R. R. & Gilbert, R. O.
Partner: UNT Libraries Government Documents Department

Gamma densitometer for measuring Pu density in fuel tubes

Description: A fuel-gamma-densitometer (FGD) has been developed to examine nondestructively the uniformity of plutonium in aluminum-clad fuel tubes at the Savannah River Plant (SRP). The monitoring technique is ..gamma..-ray spectroscopy with a lead-collimated Ge(Li) detector. Plutonium density is correlated with the measured intensity of the 208 keV ..gamma..-ray from /sup 237/U (7d) of the /sup 241/Pu (15y) decay chain. The FGD measures the plutonium density within 0.125- or 0.25-inch-diameter areas of the 0.133- to 0.183-inch-thick tube walls. Each measurement yields a density ratio that relates the plutonium density of the measured area to the plutonium density in normal regions of the tube. The technique was used to appraise a series of fuel tubes to be irradated in an SRP reactor. High-density plutonium areas were initially identified by x-ray methods and then examined quantitatively with the FGD. The FGD reliably tested fuel tubes and yielded density ratios over a range of 0.0 to 2.5. FGD measurements examined (1) nonuniform plutonium densities or hot spots, (2) uniform high-density patches, and (3) plutonium density distribution in thin cladding regions. Measurements for tubes with known plutonium density agreed with predictions to within 2%. Attenuation measurements of the 208-keV ..gamma..-ray passage through the tube walls agreed to within 2 to 3% of calculated predictions. Collimator leakage measurements agreed with model calculations that predicted less than a 1.5% effect on plutonium density ratios. Finally, FGD measurements correlated well with x-ray transmission and fluoroscopic measurements. The data analysis for density ratios involved a small correction of about 10% for ..gamma..-shielding within the fuel tube. For hot spot examinations, limited information for this correction dictated a density ratio uncertainty of 3 to 5%.
Date: January 1, 1982
Creator: Winn, W.G.
Partner: UNT Libraries Government Documents Department

Irradiated-Microsphere Gamma Analyzer (IMGA): an integrated system for HTGR coated particle fuel performance assessment

Description: The Irradiated-Microsphere Gamma Analyzer (IMGA) System, designed and built at ORNL, provides the capability of making statistically accurate failure fraction measurements on irradiated HTGR coated particle fuel. The IMGA records the gamma-ray energy spectra from fuel particles and performs quantitative analyses on these spectra; then, using chemical and physical properties of the gamma emitters it makes a failed-nonfailed decision concerning the ability of the coatings to retain fission products. Actual retention characteristics for the coatings are determined by measuring activity ratios for certain gamma emitters such as /sup 137/Cs//sup 95/Zr and /sup 144/Ce//sup 95/Zr for metallic fission product retention and /sup 134/Cs//sup 137/Cs for an indirect measure of gaseous fission product retention. Data from IMGA (which can be put in the form of n failures observed in N examinations) can be accurately described by the binomial probability distribution model. Using this model, a mathematical relationship between IMGA data (n,N), failure fraction, and confidence level was developed. To determine failure fractions of less than or equal to 1% at confidence levels near 95%, this model dictates that from several hundred to several thousand particles must be examined. The automated particle handler of the IMGA system provides this capability. As a demonstration of failure fraction determination, fuel rod C-3-1 from the OF-2 irradiation capsule was analyzed and failure fraction statistics were applied. Results showed that at the 1% failure fraction level, with a 95% confidence level, the fissile particle batch could not meet requirements; however, the fertile particle exceeded these requirements for the given irradiation temperature and burnup.
Date: February 1, 1980
Creator: Kania, M.J. & Valentine, K.H.
Partner: UNT Libraries Government Documents Department

Critical concentrations of cadmium in human liver and kidney measured by prompt-gamma neutron activation

Description: Few data exist on Cd metabolism in human beings. In particular, data are needed on the role of parameters such as age, sex, weight, diet, smoking habits, and state of health. Prompt-gamma neutron activation analysis (PGNAA) provides the only currently available means for measuring in vivo levels of liver and kidney Cd. The method employs an 85 Ci, /sup 235/Pu,Be neutron source and a gamma ray detection system consisting of two Ge(Li) detector. The dose delivered to the liver and left kidney is 666 mrem (detection limit is 1.4 ..mu..g/g Cd in the liver and 2.0 mg Cd for one kidney). Absolute levels of Cd in the kidney and concentrations of Cd in the liver were measured in vivo in twenty healthy adult males using /sup 238/Pu,Be neutron sources. Organ Cd levels of smokers were significantly elevated above those of nonsmokers. Biological half-time for Cd in the body was estimated to be 15.7 yr. Cigarette smoking was estimated to result in the absorption of 1.9 ..mu..g of Cd per pack. No relationship was bound between body stores of Cd (liver and kidney) and Cd or ..beta..-microglobulin levels in urine and blood. Currently the above neutron activation facility is being mounted on a 34-ft mobile trailer unit. This unit will be used to monitor levels of Cd in industrial workers. It is anticipated that critically important data, particularly on industrially exposed workers, will provide a better basis for determining critical concentrations and for the setting or revision of standards for industrial and environmental Cd pollution. (ERB)
Date: January 1, 1979
Creator: Cohn, S.H.; Vartsky, D.; Yasumura, S.; Zanzi, I. & Ellis, K.J.
Partner: UNT Libraries Government Documents Department