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The Self Attenuation Correction for Holdup Measurements, a Historical Perspective

Description: Self attenuation has historically caused both conceptual as well as measurement problems. The purpose of this paper is to eliminate some of the historical confusion by reviewing the mathematical basis and by comparing several methods of correcting for self attenuation focusing on transmission as a central concept.
Date: July 11, 2006
Creator: Oberer, R. B.; Gunn, C. A. & Chiang, L. G.
Partner: UNT Libraries Government Documents Department

Estimate of Legacy Tritium in Building 232-H Tritium Facility, Savannah River Site

Description: This report describes an estimate of how much tritium will be held up in those parts of the 232-H process that will remain in the building after deactivation The anticipated state of this tritium is also discussed. This information will be used to assess the radiological status of the deactivated facility.
Date: January 7, 2003
Creator: Clark, E.A.
Partner: UNT Libraries Government Documents Department

Authentication of reprocessing plant safeguards data through correlation analysis

Description: This report investigates the feasibility and benefits of two new approaches to the analysis of safeguards data from reprocessing plants. Both approaches involve some level of plant modeling. All models involve some form of mass balance, either applied in the usual way that leads to material balances for individual process vessels at discrete times or applied by accounting for pipe flow rates that leads to material balances for individual process vessels at continuous times. In the first case, material balances are computed after each tank-to-tank transfer. In the second case, material balances can be computed at any desired time. The two approaches can be described as follows. The first approach considers the application of a new multivariate sequential test. The test statistic is a scalar, but the monitored residual is a vector. The second approach considers the application of recent nonlinear time series methods for the purpose of empirically building a model for the expected magnitude of a material balance or other scalar variable. Although the report restricts attention to monitoring scalar time series, the methodology can be extended to vector time series.
Date: April 1, 1995
Creator: Burr, T.L.; Wangen, L.E. & Mullen, M.F.
Partner: UNT Libraries Government Documents Department

Far-Field Approximation in the Generalized Geometry Holdup (GGH) Model

Description: Quantitative gamma spectrometry measurements of uranium frequently require corrections for attenuation by an equipment or container layer and by the uranium bearing material itself. It is common to correct for attenuation using the ''far-field approximation''. Under this approximation, the minimum thickness of equipment or material is used for the correction rather than an average thickness over the detector field-of-view. In reality this aspect of the far-field approximation is really a narrow field-of-view approximation. The price of this simplification is the introduction of a bias. This bias will be investigated in this paper. In addition, there is a distance dependence of the radial response of a detector. This dependence will also be investigated.
Date: September 7, 2006
Creator: Oberer, R. B.; Gunn, C. A. & Chiang, L. G.
Partner: UNT Libraries Government Documents Department

Nondestructive assay (NDA) of fissile material in gloveboxes and equipment at Rocky Flats Environmental Technology Site

Description: At Rocky Flats Environmental Technology Site (RFETS), a glovebox and equipment holdup measurement program called Untoward Areas was performed in FY92. These measurements were completed in selected areas of one building. After completing this task, measurements in two other buildings had been completed to assist in characterizing their entire inventory. This information was used as part of evaluating safeguards and security requirements. However, a large percent of the gloveboxes and equipment in process buildings have not been measured. Before FY97, holdup measurements were being performed prior to decommissioning and deactivation activities. To accelerate the quantification of holdup a list of areas suspected to have high amounts of holdup was compiled and funding was requested and recently received. Glovebox and equipment locations were selected by use of several selection criteria. The following steps were taken in the selection process: (1) attribute scan results (FY95) were examined and high scan result locations were selected, (2) knowledgeable personnel within and outside the organization were consulted, and (3) video characterization of the Building 707 chainveyor system was examined. Only a few of the high scan result areas from the attribute scan list had not been identified by the use of process knowledge. The primary driver for holdup measurements is Department of energy (DOE) Order 5633.3B, Section II-3, Physical Inventories.
Date: October 1, 1997
Creator: Dreher, D.J. & Lamb, F.W.
Partner: UNT Libraries Government Documents Department

Underground natural gas storage reservoir management: Phase 2. Final report, June 1, 1995--March 30, 1996

Description: Gas storage operators are facing increased and more complex responsibilities for managing storage operations under Order 636 which requires unbundling of storage from other pipeline services. Low cost methods that improve the accuracy of inventory verification are needed to optimally manage this stored natural gas. Migration of injected gas out of the storage reservoir has not been well documented by industry. The first portion of this study addressed the scope of unaccounted for gas which may have been due to migration. The volume range was estimated from available databases and reported on an aggregate basis. Information on working gas, base gas, operating capacity, injection and withdrawal volumes, current and non-current revenues, gas losses, storage field demographics and reservoir types is contained among the FERC Form 2, EIA Form 191, AGA and FERC Jurisdictional databases. The key elements of this study show that gas migration can result if reservoir limits have not been properly identified, gas migration can occur in formation with extremely low permeability (0.001 md), horizontal wellbores can reduce gas migration losses and over-pressuring (unintentionally) storage reservoirs by reinjecting working gas over a shorter time period may increase gas migration effects.
Date: December 31, 1996
Creator: Ortiz, I. & Anthony, R.V.
Partner: UNT Libraries Government Documents Department

Licensed fuel facility status report: Inventory difference data, July 1, 1994--June 30, 1995. Volume 15

Description: The Nuclear Regulatory Commission (NRC) is committed to the periodic publication of licensed fuel facility inventory difference data, following agency review of the information and completion of any related NRC investigations. Information in this report includes inventory difference data for active fuel fabrication facilities possessing more than one effective kilogram of special nuclear material.
Date: May 1, 1996
Creator: Joy, D.R.
Partner: UNT Libraries Government Documents Department


Description: While substantial work has been performed in the Russian MPC&A Program, much more needs to be done at Russian nuclear facilities to complete four necessary steps. These are (1) periodically measuring the physical inventory of nuclear material, (2) continuously measuring the flows of nuclear material, (3) using the results to close the material balance, particularly at bulk processing facilities, and (4) statistically evaluating any apparent loss of nuclear material. The periodic closing of material balances provides an objective test of the facility's system of nuclear material protection, control and accounting. The statistical evaluation using the uncertainties associated with individual measurement systems involved in the calculation of the material balance provides a fair standard for concluding whether the apparent loss of nuclear material means a diversion or whether the facility's accounting system needs improvement. In particular, if unattractive flow material at a facility is not measured well, the accounting system cannot readily detect the loss of attractive material if the latter substantially derives from the former.
Date: July 25, 1999
Creator: FISHBONE,L.G.
Partner: UNT Libraries Government Documents Department

Ultrasonic methods for locating hold-up

Description: Hold-up remains one of the major contributing factors to unaccounted for materials and can be a costly problem in decontamination and decommissioning activities. Ultrasonic techniques are being developed to noninvasively monitor hold-up in process equipment where the inner surface of such equipment may be in contact with the hold-up material. These techniques may be useful in improving hold-up measurements as well as optimizing decontamination techniques.
Date: September 1, 1995
Creator: Sinha, D.N. & Olinger, C.T.
Partner: UNT Libraries Government Documents Department

Applications of Kalman Filtering to nuclear material control. [Kalman filtering and linear smoothing for detecting nuclear material losses]

Description: The feasibility of using modern state estimation techniques (specifically Kalman Filtering and Linear Smoothing) to detect losses of material from material balance areas is evaluated. It is shown that state estimation techniques are not only feasible but in most situations are superior to existing methods of analysis. The various techniques compared include Kalman Filtering, linear smoothing, standard control charts, and average cumulative summation (CUSUM) charts. Analysis results indicated that the standard control chart is the least effective method for detecting regularly occurring losses. An improvement in the detection capability over the standard control chart can be realized by use of the CUSUM chart. Even more sensitivity in the ability to detect losses can be realized by use of the Kalman Filter and the linear smoother. It was found that the error-covariance matrix can be used to establish limits of error for state estimates. It is shown that state estimation techniques represent a feasible and desirable method of theft detection. The technique is usually more sensitive than the CUSUM chart in detecting losses. One kind of loss which is difficult to detect using state estimation techniques is a single isolated loss. State estimation procedures are predicated on dynamic models and are well-suited for detecting losses which occur regularly over several accounting periods. A single isolated loss does not conform to this basic assumption and is more difficult to detect.
Date: October 1, 1977
Creator: Pike, D.H.; Morrison, G.W. & Westley, G.W.
Partner: UNT Libraries Government Documents Department

Enhanced safeguards via solution monitoring

Description: Solution monitoring is defined as the essentially continuous monitoring of solution level, density, and temperature in all tanks in the process that contain, or could contain, safeguards-significant quantities of nuclear material. This report describes some of the enhancements that solution monitoring could make to international safeguards. The focus is on the quantifiable benefits of solution monitoring, but qualitatively, solution monitoring can be viewed as a form of surveillance. Quantitatively, solution monitoring can in some cases improve diversion detection probability. For example, the authors show that under certain assumptions, solution monitoring can be used to reduce the standard deviation of the annual material balance, {sigma}{sub MB}, from approximately 17 kg to approximately 4 kg. Such reduction in {sigma}{sub MB} will not always be possible, as they discuss. However, in all cases, solution monitoring would provide assurance that the measurement error models are adequate so that one has confidence in his estimate of {sigma}{sub MB}. Some of the results in this report were generated using data that were simulated with prototype solution monitoring software that they are developing. An accompanying document describes that software.
Date: September 1, 1996
Creator: Burr, T. & Wangen, L.
Partner: UNT Libraries Government Documents Department

Material accountancy in an electrometallurgical Fuel Conditioning Facility

Description: The Fuel Conditioning Facility (FCF) treats spent nuclear fuel using an electrometallurgical process that separates the uranium from the fission products, sodium thermal bond and cladding materials. Material accountancy is necessary at FCF for two reasons: first, it provides a mechanism for detecting a potential loss of nuclear material for safeguards and security; second, it provides a periodic check of inventories to ensure that processes and material are under control. By weighing material entering and leaving a process, and using sampling results to determine composition, an inventory difference (ID) results when the measured inventory is compared to the predicted inventory. The ID and its uncertainty, based on error propagation, determines the degree of assurance that an operation proceeded according to expectations. FCF uses the ID calculation in two ways: closeout, which is the ID and uncertainty for a particular operational step, and material accountancy, which determines an ID and its associated uncertainty for a material balance area through several operational steps. Material accountancy over the whole facility for a specified time period assists in detecting diversion of nuclear material. Data from depleted uranium operations are presented to illustrate the method used in FCF.
Date: May 1, 1996
Creator: Vaden, D.; Benedict, R.W.; Goff, K.M.; Keyes, R.W.; Mariani, R.D.; Bucher, R.G. et al.
Partner: UNT Libraries Government Documents Department

Licensed fuel facility. Volume 14. Inventory difference data, status report, July 1, 1993--June 30, 1994

Description: The Nuclear Regulatory Commission is committed to an annual publication of licensed fuel facilities` inventory difference (ID) results, after Agency review of the information and completion of any related investigations. Information in this report includes ID results for active fuel fabrication and/or recovery facilities.
Date: March 1, 1995
Creator: Joy, D R
Partner: UNT Libraries Government Documents Department

SNM measurement uncertainites: potential impacts for materials disposition

Description: A discussion of nuclear material measurement uncertainties and impacts to the Materials Disposition (MD) Program is presented. Many of the options under consideration by the disposition program present new measurement challenges include significant material processing throughputs, a variety of material forms, unique waste streams, and difficult-to-measure matrices. There are also some questions regarding the ability to achieve International Atomic Energy Agency (IAEA) verification requirements and to achieve measurement uncertainties that are small enough to meet the IAEA loss detection goals. We present a detailed formalism for determining the measurement error for nondestructive assay systems applied to the MD Program, which is an essential component for planning the safeguards and security of these systems.
Date: September 1, 1996
Creator: Fearey, B.L.; Burr, T.L. & Pickrell, M.M.
Partner: UNT Libraries Government Documents Department

Applications of inventory difference tool at Los Alamos Plutonium Facility

Description: A prototype computer program reads the inventory entries directly from the Microsoft Access database. Based on historical data, the program then displays temporal trends and constructs a library of rules that encapsulate the system behavior. The analysis of inventory data is illustrated using a combination of realistic and simulated facility examples. Potential payoffs of this methodology include a reduction in time and resources needed to perform statistical tests and a broad applicability to DOE needs such as treaty verification.
Date: December 31, 1998
Creator: Hench, K.W.; Longmire, V.; Yarbro, T.F. & Zardecki, A.
Partner: UNT Libraries Government Documents Department

A study of the impact of bias on accountability

Description: In the area of production the primary goal is to produce a product that meets (or exceeds) customer expectations. This requires that one first obtains statistical control of the process at some desired level of operation. Once this is accomplished, one looks for ways to reduce variations around that level. The authors take corrective actions only when statistical control charts indicate that some undesirable change has occurred. They do not, for example, concern themselves with the possibility of relatively small changes that routine control chart tests do not detect. Relatively small biases are of no great concern. However, significant deviations from the desired level of operation are of great concern. In the area of materials accountability the situation is somewhat different. Here the primary goal is to maintain the best possible records of material inventories taking into account the measuring uncertainties that are associated with such inventories. In addition to the variations of individual values around averages (precision), the authors must also concern themselves with those deviations in averages from their true values (biases). The authors are faced with the problem of knowing true values with exactness, and they are faced with the problem of needing to identify those relatively small biases that behave as random variables while exhibiting little or no statistical significance.
Date: April 1, 1996
Creator: Harvey, T.R. & McGuire, S.A.
Partner: UNT Libraries Government Documents Department

High Purity Germanium Gamma-PHA Assay of Uranium Storage Pigs for 321-M Facility

Description: The Analytical Development Section of SRTC was requested by the Facilities Disposition Division (FDD) to determine the holdup of enriched uranium in the 321-M facility as part of an overall deactivation project of the facility. The 321-M facility was used to fabricate enriched uranium fuel assemblies, lithium-aluminum target tubes, neptunium assemblies, and miscellaneous components for the production reactors. The facility also includes the 324-M storage building and the passageway connecting it to 321-M. The results of the holdup assays are essential for determining compliance with the Solid Waste's Waste Acceptance Criteria, Material Control and Accountability, and to meet criticality safety controls. This report describes and documents the use of a portable HPGe detector and EG and G Dart system that contains a high voltage power supply, signal processing electronics, a personal computer with Gamma-Vision software, and space to store and manipulate multiple 4096-channel g-ray spectra to assay for 235U content in 268 uranium shipping and storage pigs. This report includes a description of three efficiency calibration configurations and also the results of the assay. A description of the quality control checks is included as well.
Date: September 18, 2001
Creator: Dewberry, R.A.
Partner: UNT Libraries Government Documents Department

Achieving Higher Accuracy in the Gamma-Ray Spectrocopic Assay of Holdup

Description: Gamma-ray spectroscopy is an important technique for the measurement of quantities of nuclear material holdup in processing equipment. Because the equipment in large facilities dedicated to uranium isotopic enrichment, uranium/plutonium scrap recovery or various stages of fuel fabrication is extensive, the total holdup may be large by its distribution alone, even if deposit thicknesses are small. Good accountability practices require unbiased measurements with uncertainties that are as small as possible. This paper describes new procedures for use with traditional holdup analysis methods based on gamma-ray spectroscopy. The procedures address the two sources of bias inherent in traditional gamma-ray measurements of holdup. Holdup measurements are performed with collimated, shielded gamma-ray detectors. The measurement distance is chosen to simplify the deposit geometry to that of a point, line or area. The quantitative holdup result is based on the net count rate of a representative gamma ray. This rate is corrected for contributions from room background and for attenuation by the process equipment. Traditional holdup measurements assume that the width of the point or line deposit is very small compared to the measurement distance, and that the self-attenuation effects can be neglected. Because each point or line deposit has a finite width and because self-attenuation affects all measurements, bias is incurred in both assumptions. In both cases the bias is negative, explaining the systematically low results of gamma-ray holdup measurements. The new procedures correct for bias that arises from both the finite-source effects and the gamma-ray self-attenuation. The procedures used to correct for both of these effects apply to the generalized geometries. One common empirical parameter is used for both corrections. It self-consistently limits the total error incurred (from uncertain knowledge of this parameter) in the combined correction process, so that it is compelling to use these procedures. The algorithms and the procedures ...
Date: September 1, 2000
Creator: Russo, P.A.; Wenz, T.R.; Smith, S.E. & Harris, J.F.
Partner: UNT Libraries Government Documents Department