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Use of the Known-M Method for NDA of Plutonium Scrap

Description: 'Plutonium scrap from another Department of Energy site is to be converted at Savannah River Site (SRS) to a form for permanent storage. For accountability and criticality safety, the material must be measured at SRS, and handling restrictions require assay in 9975 shipping drums. A Multiplicity Neutron Counter is available to perform the measurements, but requires about 12 hours per assay, too long to support the measurement schedule. The assay time has been reduced to 2 hours by use of the Known-M method, the first known routine application of Known-M. The approach involves expression of the multiplication in terms of the effective <sup>239</sup>Pu mass and a quadratic polynomial. Because only a few measured values of multiplication were available, values from Monte Carlo neutron transport calculations (using code MCNP) were used. Because the scrap cans have variable fill heights and fill height affects multiplication, an algorithm to correct the effective <sup>239</sup>Pu mass values for that effect was developed. Testing of the Known-M calibration with limited data suggests a 2-sigma uncertainty of about 5 percent. Drums can contain one or two individual scrap cans, and an algorithm for measuring the combined plutonium content in two cans was developed. The Known-M assay calculations will be performed off line using a spreadsheet.'
Date: July 22, 1999
Creator: Thompson, R.S.
Partner: UNT Libraries Government Documents Department

Designation of waste receipt assay and storage portions of WRAP as a limited control facility

Description: This evaluation designates the waste receipt, storage, assay, and shiping portions of WRAP I as a Limited Control Facility. The technical basis for this designation comes from CSERs in other facilities The limits and controls for this CSER come from other facilities. This is deemed sufficient, since any fissile material being received at WRAP I, will come from those facilities, and as long as the limits for limited control are maintained, the areas considered in this CSER can be designated appropriately.
Date: September 20, 1996
Creator: Ruben, R.H.
Partner: UNT Libraries Government Documents Department

Using Nuclear Resonance Fluorescence for Nondestructive Isotopic Analysis

Description: Nuclear resonance fluorescence (NRF) has been studied as one of the nondestructive analysis (NDA) techniques currently being investigated by a multi-laboratory collaboration for the determination of Pu mass in spent fuel. In NRF measurements specific isotopes are identified by their characteristic lines in recorded gamma spectra. The concentration of an isotope in a material can be determined from measured NRF signal intensities if NRF cross sections and assay geometries are known. The potential of NRF to quantify isotopic content and Pu mass in spent fuel has been studied. The addition of NRF data to MCNPX and an improved treatment of the elastic photon scattering at backward angles has enabled us to more accurately simulate NRF measurements on spent fuel assemblies. Using assembly models from the spent fuel assembly library generated at LANL, NRF measurements are simulated to find the best measurement configurations, and to determine measurement sensitivities and times, and photon source and gamma detector requirements. A first proof-of-principal measurement on a mock-up assembly with a bremsstrahlung photon source demonstrated isotopic sensitivity to approximately 1% limited by counting statistics. Data collection rates are likely a limiting factor of NRF-based measurements of fuel assemblies but new technological advances may lead to drastic improvements.
Date: July 14, 2010
Creator: Ludewigt, Bernhard A.; Mozin, Vladimir; Haefner, Andrew & Quiter, Brian
Partner: UNT Libraries Government Documents Department

Performance Demonstration Program Plan for Nondestructive Assay for the TRU Waste Characterization Program. Revision 1

Description: The Performance Demonstration Program (PDP) for Nondestructive Assay (NDA) consists of a series of tests conducted on a regular frequency to evaluate the capability for nondestructive assay of transuranic (TRU) waste throughout the Department of Energy (DOE) complex. Each test is termed a PDP cycle. These evaluation cycles provide an objective measure of the reliability of measurements performed with TRU waste characterization systems. Measurement facility performance will be demonstrated by the successful analysis of blind audit samples according to the criteria set by this Program Plan. Intercomparison between measurement groups of the DOE complex will be achieved by comparing the results of measurements on similar or identical blind samples reported by the different measurement facilities. Blind audit samples (hereinafter referred to as PDP samples) will be used as an independent means to assess the performance of measurement groups regarding compliance with established Quality Assurance Objectives (QAOs). As defined for this program, a PDP sample consists of a 55-gallon matrix drum emplaced with radioactive standards and fabricated matrix inserts. These PDP sample components, once manufactured, will be secured and stored at each participating measurement facility designated and authorized by Carlsbad Area Office (CAO) under secure conditions to protect them from loss, tampering, or accidental damage.
Date: May 1, 1997
Partner: UNT Libraries Government Documents Department

Nondestructive assay of fissile material samples in support of nuclear safeguards

Description: From nuclear science symposium; San Francisco, California, USA (14 Nov 1973). Samples of fissile material can be assayed by bombarding with 300- to 600- keV neutrons and counting delayed neutrons from fission. Interrogating neutron energy selection is based upon considerations of sample penetrability and insensitivity of response to nonfissile isotopes. Significant cost savings in nuclear safeguards and quality control are possible. (auth)
Date: January 1, 1973
Creator: Evans, A.E. Jr.
Partner: UNT Libraries Government Documents Department

Interpretation of data obtained from non-destructive and destructive post-test analyses of an intact-core column of culebra dolomite

Description: The U.S. Department of Energy (DOE) has been developing a nuclear waste disposal facility, the Waste Isolation Pilot Plant (WIPP), located approximately 42 km east of Carlsbad, New Mexico. The WIPP is designed to demonstrate the safe disposal of transuranic wastes produced by the defense nuclear-weapons program. Pefiormance assessment analyses (U.S. DOE, 1996) indicate that human intrusion by inadvertent and intermittent drilling for resources provide the only credible mechanisms for significant releases of radionuclides horn the disposal system. These releases may occur by five mechanisms: (1) cuttings, (2) cavings, (3) spallings, (4) direct brine releases, and (5) long- term brine releases. The first four mechanisms could result in immediate release of contaminant to the accessible environment. For the last mechanisq migration pathways through the permeable layers of rock above the Salado are important, and major emphasis is placed on the Culebra Member of the Rustler Formation because this is the most transmissive geologic layer in the disposal system. For reasons of initial quantity, half-life, and specific radioactivity, certain isotopes of T~ U, Am, and Pu would dominate calculated releases from the WIPP. In order to help quantifi parameters for the calculated releases, radionuclide transport experiments have been carried out using five intact-core columns obtained from the Culebra dolomite member of the Rustler Formation within the Waste Isolation Pilot Pknt (WIPP) site in southeastern New Mexico. This report deals primarily with results of analyses for 241Pu and 241Am distributions developed during transport experiments in one of these cores. All intact-core column transport experiments were done using Culebra-simukmt brine relevant to the core recovery location (the WIPP air-intake shaft - AK). Hydraulic characteristics (i.e., apparent porosity and apparent dispersion coefficient) for intact-core columns were obtained via experiments using conservative tracer `Na. Elution experiments carried out over periods of a few days with ...
Date: September 1, 1998
Creator: Lucero, Daniel L. & Perkins, W. George
Partner: UNT Libraries Government Documents Department

Experience operating LANL`s passive/active neutron (PAN) assay system

Description: We present a summary of our operating experience with LANL`s mobile PAN assay system, which was acquired from the Carlsbad Area Office in 1994, refurbished, calibrated, and fielded for the first time on LANL`s TRU waste in the winter of 1996. It is functionally identical to other PAN systems throughout the DOE complex and its software is the same as at INEL. Since Jan. 1996, it has passed the first round of the Performance Demonstration Program and has been used to assay several hundred drums of LANL`s TRU waste. Difficulties in assaying homogeneous wastes with high ({alpha},n) neutron fluxes and experience in assaying debris waste in both active and passive PAN modes are reported on.
Date: January 1, 1997
Creator: Taggart, D.P.; Betts, S.E.; Martinez, E.F.; Mendez, J.L.; Rael, C.D. & Vigil, J.J.
Partner: UNT Libraries Government Documents Department

Using NAI detectors for tomographic gamma scanning

Description: The authors examined two approaches for using NaI detectors to perform transmission corrections used in the tomographic gamma scanner (TGS) and segmented gamma scanner (SGS) nondestructive assay methods. They found that a material-basis-set (MBS) fit using empirical logarithmic response spectra is quite accurate. Because this is a gross count technique, it gives sensitivities (for equal numbers of detectors) that are roughly ten times better than those obtained using Germanium detectors. The authors also found that simple continuum subtraction can be used in MBS fits using the energy-group-analysis technique only when the Pu transmission is greater than 10%. Both approaches for using NaI detectors require a knowledge of the Pu (or other) isotopics to obtain full accuracy.
Date: March 1, 1997
Creator: Estep, R.J. & Melton, S.
Partner: UNT Libraries Government Documents Department

A Sludge Drum in the APNea System

Description: The assay of sludge drums pushes the APNea System to a definite extreme. Even though it seems clear that neutron based assay should be the method of choice for sludge drums, the difficulties posed by this matrix push any NDA technique to its limits. Special emphasis is given here to the differential die-away technique, which appears to approach the desired sensitivity. A parallel analysis of ethafoam drums will be presented, since the ethafoam matrix fits well within the operating range of the AIWea System, and, having been part of the early PDP trials, has been assayed by many in the NDA community.
Date: November 17, 1998
Creator: Hensley, D.
Partner: UNT Libraries Government Documents Department

International Atomic Energy Agency/Hanford Site shared use of calorimeters

Description: Hanford Site operators combine gamma ray isotopic and calorimetry measurements for nondestructive plutonium assay. Such measurements offer lower variability (particularly for heterogeneous materials) and decreased radiation exposure, cost, waste, intrusiveness, and material handling compared to destructive analysis. Until now, the International Atomic Energy Agency (IAEA) has relied on destructive analysis to perform the most accurate verification requirements for plutonium stored under safeguards at the Hanford Site. It was recognized that using calorimetry could significantly reduce the need for the IAEA to perform destructive analysis. To authorize the operator`s calorimeters for routine IAEA use, however, it was necessary to develop authentication features and perform independent 1558 testing. Authentication features include IAEA control of the hardware and calorimeter operating system software, measurement of certified IAEA standards, sealing of calorimeter chambers, and limited destructive analysis of IAEA selected items. A field test of these authentication features was performed at the Hanford Site in June 1997. The field test also was meant to enhance the credibility the IAEA imputes to calorimetry prior to its implementation. Progress in shared use of the Hanford Site calorimeters is reported.
Date: July 21, 1997
Creator: Welsh, T. L.
Partner: UNT Libraries Government Documents Department

IMAP: Interferometry for Material Property Measurement in MEMS

Description: An interferometric technique has been developed for non-destructive, high-confidence, in-situ determination of material properties in MEMS. By using interferometry to measure the full deflection curves of beams pulled toward the substrate under electrostatic loads, the actual behavior of the beams has been modeled. No other method for determining material properties allows such detailed knowledge of device behavior to be gathered. Values for material properties and non-idealities (such as support post compliance) have then been extracted which minimize the error between the measured and modeled deflections. High accuracy and resolution have been demonstrated, allowing the measurements to be used to enhance process control.
Date: March 10, 1999
Creator: Jensen, B.D.; Miller, S.L. & de Boer, M.P.
Partner: UNT Libraries Government Documents Department

Probabilistic model for pressure vessel reliability incorporating fracture mechanics and nondestructive examination

Description: A probabilistic model has been developed for predicting the reliability of structures based on fracture mechanics and the results of nondestructive examination (NDE). The distinctive feature of this model is the way in which inspection results and the probability of detection (POD) curve are used to calculate a probability density function (PDF) for the number of flaws and the distribution of those flaws among the various size ranges. In combination with a probabilistic fracture mechanics model, this density function is used to estimate the probability of failure (POF) of a structure in which flaws have been detected by NDE. The model is useful for parametric studies of inspection techniques and material characteristics.
Date: March 1, 1998
Creator: Tow, D.M. & Reuter, W.G.
Partner: UNT Libraries Government Documents Department

Microsensors to monitor missile storage and maintenance needs

Description: Accurate assessments of reliability and condition based maintenance can only be implemented where a good understanding of ammunition stockpile condition exists. Use of miniaturized intelligent sensors provides an inexpensive means of nondestructively gaining insight into stockpile condition while keeping costs low. In the past, evaluation of ammunition lifetimes has utilized humidity, temperature, pressure, shock, and corrosion. New technologies provide the possibility of obtaining these environmental parameters, as well as a number of other indicators of propellant degradation, including NOx by utilizing a microsensor with capability for remote wireless monitoring. Micro-electro-mechanical systems (MEMS) like microcantilevers promise to revolutionize the field of sensor design. In the automobile industry, micromachined acceleration sensors are now used for triggering airbags and pressure sensors adjust the air-fuel intake ratio in the engine. By applying coatings to the sensor`s surface the behavior of the microdevice can be measurably altered to respond to chemical species as demonstrated by ORNL using microcantilevers to detect mercury vapor and humidity. Ultimately, single-chip detectors with electronics and telemetry could be developed with conceivably hundreds of individual microsensors on each chip to simultaneously monitor identify, and quantify many important chemical species for ammunition as well as measure environmental parameters.
Date: October 30, 1997
Creator: Mee, D.K.; Thundat, T.G. & Oden, P.I.
Partner: UNT Libraries Government Documents Department

Characterization of an enriched uranyl fluoride deposit in a valve and pipe intersection using time-of-flight transmission measurements with {sup 252}Cf

Description: A method was developed and successfully applied to characterize large uranyl fluoride (UO{sub 2}F{sub 2}) deposits at the former Oak Ridge Gaseous Diffusion Plant. These deposits were formed by a wet air in-leakage into the UF{sub 6} process gas lines over a period of years. The resulting UO{sub 2}F{sub 2} is hygroscopic, readily absorbing moisture from the air to form hydrates as UO{sub 2}F{sub 2}-nH{sub 2}O. The ratio of hydrogen to uranium can vary from 0--16, and has significant nuclear criticality safety impacts for large deposits. In order to properly formulate the required course of action, a non-intrusive characterization of the distribution of the fissile material within the pipe, its total mass, and amount of hydration was necessary. The Nuclear Weapons Identification System (NWIS) previously developed at the Oak Ridge Y-12 Plant for identification of uranium weapons components in storage containers was used to successfully characterize these deposits.
Date: June 1, 1998
Creator: Wyatt, M.S.; Uckan, T.; Mihalczo, J.T.; Valentine, T.E. & Hannon, T.F.
Partner: UNT Libraries Government Documents Department

Active and passive computed tomography for nondestructive assay

Description: Traditional gamma-ray methods used to characterize nuclear waste introduce errors that are related to non-uniform measurement responses associated with unknown radioactive source and matrix material distributions. These errors can be reduced by applying an active and passive tomographic technique (A&PCT) developed at the Lawrence Livermore National Laboratory (LLNL). The technique uses an external radioactive source and active tomography to map the attenuation within a waste barrel as a function of mono-energetic gamma-ray energy. Passive tomography is used to localize and identify specific radioactive waste within the same container. Reconstruction of the passive data using the attenuation maps at specific energies allows internal waste radioactivity to be corrected for any overlying heterogeneous materials, thus yielding an absolute assay of the waste activity. LLNL and Bio-Imaging Research, Inc. have collaborated in a technology transfer effort to integrate an A&PCT assay system into a mobile waste characterization trailer. This mobile system has participated in and passed several formal DOE-sponsored performance demonstrations, tests and evaluations. The system is currently being upgraded with multiple detectors to improve throughput, automated gamma-ray analysis code to simplify the assay, and a new emission reconstruction code to improve accuracy
Date: October 28, 1998
Creator: Bernardi, R T; Camp, D E; Clard, D; Jackson, J A; Martz, H E, Decman, D J & Roberson, G P
Partner: UNT Libraries Government Documents Department

Statistics to Identify and quantify Pure Radionuclides by Their Neutron Emission Patterns

Description: Perfect knowledge of emission time for every neutron from a radionuclide allows identification of the material and estimation of the quantity present via nondestructive assay. In practice, the authors lack this perfect knowledge. Detector efficiency is less than unity, thermalized neutron arrival is delayed randomly, and neutron showers triggered by cosmic rays in the atmosphere add noise to the process. They compare two classes of statistical estimators capable of recovering characteristic parameters for radionuclides from this imperfect information: method of moments (the current standard) and maximum likelihood, which holds the advantage as the number of parameters to be estimated simultaneously increases.
Date: July 27, 1999
Creator: Kiffe, J. & Rock, J.C.
Partner: UNT Libraries Government Documents Department