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Neutron radiographic detection limits of fluids in metal pipes

Description: Thermal neutron radiography has been used to image thin films of various fluids in thick-walled high-pressure process pipes. A 3.5 x 10$sup 6$ n/(cm$sup 2$-sec) thermal neutron beam and standard transfer imaging techniques were used to provide radiographs of the fluid-bearing pipes. In addition, a computer graphics procedure was developed which simulated the neutron radiographs; this method permitted examination of some fluid-pipe configurations not studied experimentally. Actual pipe outer dia ranged from $sup 1$/$sub 4$ to $sup 9$/ $sub 16$ in. (OD/ID = 3), but the graphics method was used for some cases outside this range. Fluids in the thermal cross section range 0.29 cm$sup -1$ less than or equal to $Sigma$/sub th//sup f/ less than or equal to 3.47 cm$sup - 1$ were examined for pipes with 0.099 cm$sup -1$ less than or equal to $Sigma$/ sub th//sup p/ less than or equal to 1.15 cm$sup -1$. For $Sigma$/sub th//sup f/ greater than $Sigma$/sub th//sup p/, the smallest measured film thickness t/sub s/ varied 0.006 to 0.040 in. with decreasing $Sigma$/sub th//sup f/; a semiempirical model described t/sub s/ = t/sub r/ + t/sub a/, where t/sub r/ corresponded to resolution and t/sub a/ depended on the bulk attenuation strength of the fluid. For $Sigma$/sub th//sup f/ less than $Sigma$/sub th//sup p/, part of the fluid film t/sub m/ was masked by the pipe. The calculated physical film thickness t/sub p/ = t/sub a/ + t/sub m/ ranged from 0.003 to 0.035 in. for smallest detected fluid films. Detection of low $Sigma$/sub th/ fluids was improved as much as 60 percent when the pipes were tilted 60$sup 0$ toward the neutron beam. Other options for improved detection were investigated using simulated radiographs. (auth)
Date: January 1, 1975
Creator: Winn, W.G.
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

A sample compositing strategy for classifying non-radioactive hazardous waste for transport

Description: A probabilistic strategy for sample compositing is developed to minimize the radiometric analyses required for classifying non-radioactive waste for transport. Such waste must have concentrations of total radioactivity that are below an acceptance limit of L = 2 nCi/g. A composite of N different samples must have a radioactive concentration below L/N to assure that no individual sample is unacceptable. Unacceptable samples are eventually identified by analyses of successive splits composited with N/2, N/4, {hor ellipsis} of the original samples. The probable number of such analyses is derived using Gaussian distributions for the composite concentrations, per invoking the Central Limit Theorem. A preliminary compositing strategy, based only on the average concentration {mu}, uses N = L/{mu} to yield a minimum fraction of {approx}2{mu}/L analyses per total samples. These approximations are useful for L/{mu} > 4. Refined strategies, based on both the {mu} and {sigma} for the concentration distribution, define the optimization more precisely. Experimental data from composites of 880 samples of low-level radiometric waste are consistent with the calculated predictions. 11 refs., 4 figs., 1 tab.
Date: June 1, 1990
Creator: Winn, W.G.
Partner: UNT Libraries Government Documents Department

Radioactive effluents in Savannah River. Summary report for 1996

Description: During 1996, the radioactive effluents in the Savannah River were generally comparable to (or lower than) those observed during the earlier years of these studies, being orders of magnitude below DOE and EPA/CFR guide levels. Relative to SRS and Plant Vogtle, the upstream site at Shell Bluff and the downstream side at Highway 301 Bridge are the only resin sampler sites still in service. Vogtle associated activities were largest during June to August, and they are dominated by {sup 60}Co as was the case in 1995. In earlier years, Vogtle effluents had been dominated by {sub 58}Co. The maximum observed {sub 58}Co and {sub 60}Co were 52 fCi/L and 162 fCi/L; however, values an order of magnitude greater are projected just downstream of Plant Vogtle, as noted earlier. In addition to {sub 58}Co and {sub 60}Co, Vogtle activities for {sub 54}Mn was correlated. SRS associated gamma activities were for {sub 137}Cs, which were observed at levels consistent with known SRS sources. In 1996, an isotope-specific resin was used for cesium collection, and this resulted in a maximum observed {sub 137}Cs of 85 fCi/L at Highway 301 Bridge. The standard resin yielded a maximum of 54 fCi/L, which is comparable to the 1995 result. Although the isotopic-specific resin generally yielded the higher {sub 137}Cs concentration, the larger of the two resin values was adopted for conservatism.
Date: May 28, 1997
Creator: Winn, W.G.
Partner: UNT Libraries Government Documents Department

Summary of gamma spectrometry on local air samples from 1985--1995

Description: This report summarizes the 1985--1995 results of low-level HPGe gamma spectrometry analysis of high-volume air samples collected at the Aiken Airport, which is about 25 miles north of SRS. The author began analyzing these samples with new calibrations using the newly developed GRABGAM code in 1985. The air sample collections were terminated in 1995, as the facilities at the Aiken Airport were no longer available. Air sample measurements prior to 1985 were conducted with a different analysis system (and by others prior to 1984), and the data were not readily available. The report serves to closeout this phase of local NTS air sample studies, while documenting the capabilities and accomplishments. Hopefully, the information will guide other applications for this technology, both locally and elsewhere.
Date: April 2, 1997
Creator: Winn, W.G.
Partner: UNT Libraries Government Documents Department

Enrichment Monitor for 235U Fuel Tubes

Description: This report describes the performance of this prototype y-monitor of 235 Uranium enrichment. In this proposed method y-rates associated with 235U and 232U are correlated with enrichment. Instrumentation for appraising fuel tubes with this method has been assembled and tested.
Date: August 22, 2001
Creator: Winn, W.G.
Partner: UNT Libraries Government Documents Department

Uranium Density and Enrichment in Fuel Tubes Determined from 232U and 235U Y-Activities

Description: Gamma spectroscopy is used to determine 235U density and enrichment in U-Al fuel tubes containing recycled fuel. A collimated HPGe Y-detector views the tube surface, such that U-Al disk volumes of 6.35 mm diameter and approximately 1.0 mm thickness are examined. The Y-activities from 232U and 235U, along with the tube design parameters, are used to deduce the attenuation-corrected results. Respective density and enrichment variations of less than 1 percent and less than 0.6e percent were measurable with 2000 sec counting time per tube location. Such measurements are useful for certifying tube quality and characterizing problems associated with blending the U-Al alloy.
Date: May 25, 1984
Creator: Winn, W.G.
Partner: UNT Libraries Government Documents Department

Nondestructive Assay of Uranium Enrichment with Gamma Rays

Description: An instrument has been developed and tested for nondestructive assay of 235U enrichment of uranium oxide powder contained in sealed 1-gallon cans. A theoretical correlation of enrichment vs. count rate agrees well with the calibration measurements and provides guidelines for applicability. A microcomputer simplifies operator requirements and provides on-line enrichment results.
Date: November 23, 1982
Creator: Winn, W.G.
Partner: UNT Libraries Government Documents Department

Radioactive effluents in Savannah River. Summary Report for 1995

Description: During 1995, the radioactive effluents in the Savannah River were generally lower but comparable to those observed during the earlier years of these studies, being orders of magnitude below DOE and EPA/CFR guide levels. Vogtle has only one notable effluent release in 1995. In earlier year, Vogtle effluents had been dominated by {sub 58}Co; however, in 1995 {sub 60}Co exhibited the overall maximum at 1.31 pCi/L, which is almost three times larger than the previous {sub 60}Co maximum of 0.49 pCi/L observed in 1988. By comparison, the {sub 58}Co maximum was 0.46 pCi/L, which was lower than its maxima in earlier years. In addition to {sub 58}Co and {sub 60}Co, Vogtle activities of {sub 54}Mn, {sub 57}Co, {sub 95}Nb, and {sub 95}Zr were observed. The above activities were observed from samples just downstream of Vogtle, but these samples were discontinued in October due to funding priorities. In addition, {sub 137}Cs was detected, but its levels are consistent with known SRS sources. The maximum for {sub 137}Cs was 49 fCi/L at Highway 301 Bridge.
Date: June 27, 1996
Creator: Winn, W.G.
Partner: UNT Libraries Government Documents Department

Radioactive effluents in Savannah River -- Summary report for 1991

Description: During 1991, low-level radiometric studies of the Savannah River continued to distinguish between effluent contributions from Plant Vogtle and the Savannah River Site. Measurements of these radioactive effluents are of mutual interest to both institutions, as they can address disturbing trends before they become health and legal concerns. During 1991, the radioactive effluents in the Savannah River were somewhat less than those observed in 1990. This decreasing trend has followed Vogtle improvements in pre-processing their liquid effluents. These effluents continue to be dominated by {sup 58}Co, which had a maximum concentration of only 0.21 pCi/L, which is an order of magnitude lower than the maximum observed in 1990. Many of the other man-made radionuclides observed in 1987--1990 have now decreased to where some are not even detected, and no new radionuclides were detected in the 1991 Vogtle effluents.
Date: July 16, 1992
Creator: Winn, W. G.
Partner: UNT Libraries Government Documents Department

Radioactive effluents in Savannah River. Summary report for 1993-1994

Description: During 1993-1994, low-level radiometric studies of the Savannah River continued to distinguish between effluent contributions from Plant Vogtle and the Savannah River Site. Measurements of these radioactive effluents are of mutual interest to both institutions, as they can address abnormal trends before they become health and legal concerns. The Environmental Technology Section (ETS) has conducted radiometric studies of Plant Vogtle since late 1986, prior to its startup. The plant has two 1100 MWe pressurized water reactors developed by Westinghouse, Unit 1 started commercial operations in June 1987, and Unit 2 began in May 1989. During powered operations, ETS has routinely detected neutron-activated isotopes in controlled releases but all activities have been orders of magnitude below the DOE guide values and EPA/CFR levels. In 1993-1994, Vogtle effluents continued to contribute low activities to the river. The Vogtle release data and the ETS measurements have tracked well over the past eight years.
Date: March 17, 1995
Creator: Winn, W.G.
Partner: UNT Libraries Government Documents Department

Radioactive effluents in Savannah River. Summary report for 1997

Description: The Nonproliferation Technology Section (NTS), formerly Environmental Technology Section (ETS), has conducted radiometric studies of Plant Vogtle since late 1986, seven months prior to its startup. This program has now been terminated as of May of this year, as support funding is no longer available, The present report presents the final 1997 measurements, as a closeout of this program of study, Plant Vogtle has two 1100 MWe pressurized water reactors developed by Westinghouse. Unit 1 started commercial operations in June 1987, and Unit 2 began in May 1989, During powered operations, NTS routinely detected neutron-activated isotopes in controlled releases but all activities had been orders of magnitude below the DOE guide values and EPA/CFR levels. The Vogtle release data and the NTS measurements have tracked well over the past ten years. These very sensitive ultra low-level measurements of the radioactive effluents have been important to both institutions, as they could address abnormal trends before they became health and compliance concerns.
Date: July 7, 1997
Creator: Winn, W.G.
Partner: UNT Libraries Government Documents Department

A probabilistic strategy for compositing samples for waste analysis

Description: A probabilistic strategy for sample compositing was developed to minimize the volume of waste sample analyses. Disposable waste must have a contaminant concentration below an acceptance Limit L. A composite of N different samples must have a contaminant concentration below L/N, to assure that no individual sample is unacceptable. Unacceptable samples are eventually identified by analyses of successive splits composited with N/2, N/4,... of the original samples. The probable number of such analyses is derived using conservative log-Normal distributions to model the concentration probabilities. A minimum number of analyses result when N = L/a, where a is the average contaminant concentration expected for the sample. The approximation is useful for L/a {ge} 5. Experimental composites from 880 samples with L/a = 41.8 are consistent with the calculated predictions.
Date: December 31, 1989
Creator: Winn, W.G.
Partner: UNT Libraries Government Documents Department

Environmental measurements at the Savannah River Site with Underwater gamma detectors

Description: Underwater NAI(Tl) and HPGe detectors are used in the environmental measurements programs at the Savannah River Site (SRS). A 22.9 cm {times} 10.2 cm NAI(Tl) detector on the Savannah River continuously monitors effluent releases from both SRS (DOE) and Plant Vogtle (Georgia Power). Correlations with known releases indicate a sensitivity of 4 mBq/l for {sup 58}Co with 1500 min spectra; such levels are well below those of hazardous or legal concern. A 30%-efficient HPGE detector has appraised radionuclides in SRS cooling pond sediments; the dominant gamma-emitting radionuclide detected was {sup 137}Cs, at levels ranging up to 2.0 MBq/m{sup 2}. The pond activities were adequately quantified by 1 min counts with the HPGE detector; resulting contour maps of sediment {sup 137}Cs provided guidance for partially draining the ponds for dam repairs.
Date: December 31, 1994
Creator: Winn, W.G.
Partner: UNT Libraries Government Documents Department

Measurements of radionuclides in Pond C with an underwater HPGe detector

Description: This study on Pond C is part of a broader effort to appraise Savannah River Site (SRS) waterways impacted by the Par Pond Dam remediation program that commenced 1991. In addition, the results were sought to provide a more complete appraisal of the status of historical radioactive releases that remain in the Lower Three Runs system. Gamma emitting radionuclide concentrations in Pond C sediment were measured with an underwater HPGe detector. The predominant radionuclide was Cs-137 and the only other radionuclide detected was Co-60, which was only 1% as intense as the Cs-137. At the time of the measurements (November 1992), the total Pond C inventory of {sup 137}Cs was 4.5 {plus_minus} 0.8 Ci of which 0.30 {plus_minus} 0.09 Ci was exposed during a 6-ft drawdown for Par Pond Dam repairs. The Pond C inventory of Cs-137 is only 10% of that of Par Pond, primarily because of the much larger area of Par Pond. However, Pond C has a larger average sediment concentration of 8.1 {mu}Ci/m{sup 2} compared to 4.5 {mu}Ci/m{sup 2} for Par Pond, which is consistent with Pond C being closer to the origins of the earlier SRS reactor releases. The maximum Cs-137 concentration observed for Pond C was 55 {mu}Ci/m{sup 2}, which is about 10% higher than the maximum observed for Par Pond.
Date: August 1, 1995
Creator: Winn, W.G.
Partner: UNT Libraries Government Documents Department

Radioactive effluents in Savannah River. Summary report for 1992

Description: During 1992, the radioactive effluents in the Savannah River were less than those observed in 1991. Vogtle reported no significant releases in 1992, and in earlier years Vogtle improvements in pre-processing their releases had already effected a decreasing trend in release levels. Their effluents continue to be dominated by {sup 58}Co, which had a maximum concentration of only 0.068 pCi/L, which is just 1/3 of the maximum observed in 1991. Many of the other man-made radionuclides observed in earlier years have now decreased to where some are not even detected, and no new radionuclides were detected in the 1992 Vogtle effluents. In addition to {sup 58}Co, low levels of {sup 60}Co were frequently observed, but only traces of {sup 54}Mn and {sup 95}Nb were observed. Contrary to earlier years no {sup 51}Cr, {sup 57}Co, {sup 59}Fe, or {sup 95}Zr were seen in 1992. Tritium and {sup 137}Cs were also monitored, but their levels generally remain consistent with known SRS sources. The maximum tritium observed near Vogtle was 2 pCi,/mL. The maximum downstream tritium was higher (3.8 pCi/mL), primarily due to the tritium release from K-Reactor in December 1991; however, the levels had abated significantly prior to collection of the tritium samples of the present study. In addition to natural sources, the general levels in the Savannah River are due to routine releases from the effluent treatment facility and seepage basin migration into plant streams that flow into the river.
Date: September 21, 1993
Creator: Winn, W.G.
Partner: UNT Libraries Government Documents Department

New {sup 232}U/{sup 228}Th Gamma Source for Tritiated Water Monitor

Description: The {sup 232}U/{sup 228}Th source has been tested for operation with the tritiated water monitor. This source has an effective half-life of 73 years and is an attractive replacement for the reactor activated {sup 24}Na sources, which have half-life of only 15 hours. The tests described in this report appraise the adequacy of this source by comparing its performance to that of {sup 24}Na used in earlier studies. The new source has already been used successfully to assist recovery operations, and it is now apparent that the monitor is ready to be turned over to SRP for routine use.
Date: July 17, 2001
Creator: Winn, W.G.
Partner: UNT Libraries Government Documents Department

GRABGAM: A Gamma Analysis Code for Ultra-Low-Level HPGe SPECTRA

Description: The GRABGAM code has been developed for analysis of ultra-low-level HPGe gamma spectra. The code employs three different size filters for the peak search, where the largest filter provides best sensitivity for identifying low-level peaks and the smallest filter has the best resolution for distinguishing peaks within a multiplet. GRABGAM basically generates an integral probability F-function for each singlet or multiplet peak analysis, bypassing the usual peak fitting analysis for a differential f-function probability model. Because F is defined by the peak data, statistical limitations for peak fitting are avoided; however, the F-function does provide generic values for peak centroid, full width at half maximum, and tail that are consistent with a Gaussian formalism. GRABGAM has successfully analyzed over 10,000 customer samples, and it interfaces with a variety of supplementary codes for deriving detector efficiencies, backgrounds, and quality checks.
Date: July 28, 1999
Creator: Winn, W. G.
Partner: UNT Libraries Government Documents Department

GRABGAM Analysis of Ultra-Low-Level HPGe Gamma Spectra

Description: The GRABGAM code has been used successfully for ultra-low level HPGe gamma spectrometry analysis since its development in 1985 at Savannah River Technology Center (SRTC). Although numerous gamma analysis codes existed at that time, reviews of institutional and commercial codes indicated that none addressed all features that were desired by SRTC. Furthermore, it was recognized that development of an in-house code would better facilitate future evolution of the code to address SRTC needs based on experience with low-level spectra. GRABGAM derives its name from Gamma Ray Analysis BASIC Generated At MCA/PC.
Date: July 28, 1999
Creator: Winn, W.G.
Partner: UNT Libraries Government Documents Department

Radioactive effluents in the Savannah River: Summary report for 1989

Description: Researchers at the Savannah River Site have low-level radiometric studies of the Savannah River to distinguish between the effluent contributions of the Savannah River Site and Plant Vogtle. Since the startup of Plant Vogtle in 1987, researchers have routinely detected neutron-activated isotopes in controlled releases, but all have routinely detected neutron-activated isotopes in controlled releases, but all have been well below the Department of Energy's (DOE) guidelines. The study has found that processing improvement at Plant Vogtle during 1989 have lowered the activities of effluents from Plant Vogtle. These studies will continue on a routine basis because they provide disturbing trends before actual health concerns evolve.
Date: September 1, 1991
Creator: Winn, W.G.
Partner: UNT Libraries Government Documents Department

Gamma-ray spectrometry of LDEF samples at SRL

Description: A total of 31 samples from the Long Duration Exposure Facility (LDEF), including materials of aluminum, vanadium, and steel trunnions were analyzed by ultra-low-level gamma spectroscopy. The study quantified particle induced activations of {sup 22}Na, {sup 46}Sc, {sup 51}Cr, {sup 54}Mn, {sup 56}Co, {sup 57}Co, {sup 58}Co, and {sup 60}Co. The samples of trunnion sections exhibited increasing activity toward the outer end of the trunnion and decreasing activity toward its radial center. The trunnion sections did not include end pieces, which have been reported to collect noticeable {sup 7}Be on their leading surfaces. No significant {sup 7}Be was detected in the samples analyzed. The Underground Counting Facility at Savannah River Laboratory (SRL) was used in this work. The facility is 50 ft. underground, constructed with low-background shielding materials, and operated as a clean room. The most sensitive analyses were performed with a 90%-efficient HPGe gamma-ray detector, which is enclosed in a purged active/passive shield. Each sample was counted for one to six days in two orientations to yield more representative average activities for the sample. The non-standard geometries of the LDEF samples prompted the development of a novel calibration method, whereby the efficiency about the samples surfaces (measured with point sources) predicted the efficiency for the bulk sample.
Date: July 22, 1991
Creator: Winn, W.G.
Partner: UNT Libraries Government Documents Department

Gamma-ray spectrometry of LDEF samples

Description: A total of 31 samples from the Long Duration Exposure Facility (LDEF), including materials of aluminum, vanadium, and steel trunnions were analyzed by ultra-low-level gamma spectroscopy. The study quantified particle induced activations of (sup 22)Na, {sup 46}Sc, {sup 51}Cr, {sup 54}Mn, {sup 56}Co, {sup 57}Co, {sup 58}Co, and {sup 60}Co. The samples of trunnion sections exhibited increasing activity toward the outer end of the trunnion and decreasing activity toward its radial center. The trunnion sections did not include end pieces, which have been reported to collect noticeable {sup 7}Be on their leading surfaces. No significant {sup 7}Be was detected in the samples analyzed. The Underground Counting Facility at Savannah River Laboratory (SRL) was used in this work. The facility is 50 ft. underground, constructed with low-background shielding materials, and operated as a clean room. The most sensitive analyses were performed with a 90%-efficient HPGe gamma-ray detector, which is enclosed in a purged active/passive shield. Each sample was counted for one to six days in two orientations to yield more representative average activities for the sample. The non-standard geometries of the LDEF samples prompted the development of a novel calibration method, whereby the efficiency about the samples surfaces (measured with point sources) predicted the efficiency for the bulk sample.
Date: January 1, 1991
Creator: Winn, W.G.
Partner: UNT Libraries Government Documents Department