Hybrid KED/XRF measurement of minor actinides in reprocessing plants

Minor actinides have received considerable attention recently in the nuclear power industry. Because of their potential value as recycle fuels in thermal and breeder reactors, reprocessing plants may have an economic incentive to extract Np, Am, and Cm from their waste streams. This report discusses the technique of hybrid densitometry and its potential to measure Np and Am in reprocessing plants. Precision estimates are made for the hybrid analysis of Np and Am in two types of dissolver solutions

Hybrid instrument development for an analytical laboratory

The authors have been developing a hybrid densitometer for general laboratory application. This type of densitometer can be applied to concentration determinations of thorium, uranium, neptunium, plutonium, and americium. It can also be used to determine the ratios of any combination of these nuclear materials. This report describes the hardware and analysis approach. They will also describe some laboratory tests performed with the densitometer and present actual in-plant application results

Assay of low-level plutonium effluents

In the plutonium recovery section at the Los Alamos National Laboratory, an effluent solution is generated that contains low plutonium concentration and relatively high americium concentration. Nondestructive assay of this solution is demonstrated by measuring the passive L x-rays following alpha decay. Preliminary results indicate that an average deviation of 30% between L x-ray and alpha counting can be achieved for plutonium concentrations above 10 mg/L and Am/Pu ratios of up to 3; for plutonium concentrations less than 10 mg/L, the average deviation is 40%. The sensitivity of the L x-ray assay is approx. 1 mg Pu/L

Measurement control program for NDA instruments

Measurement control checks for nondestructive assay instruments have been a constant and continuing concern at Los Alamos National Laboratory. This paper summarizes the evolution of the measurement control checks in the various high-resolution gamma systems we have developed. In-plant experiences with these systems and checks will be discussed. Based on these experiences, a set of measurement control checks is recommended for high-resolution gamma-ray systems

Nondestructive assay system development for a plutonium scrap recovery facility

A plutonium scrap recovery facility is being constructed at the Savannah River Plant (SRP). The safeguards groups of the Los Alamos National Laboratory have been working since the early design stage of the facility with SRP and other national laboratories to develop a state-of-the-art assay system for this new facility. Not only will the most current assay techniques be incorporated into the system, but also the various nondestructive assay (NDA) instruments are to be integrated with an Instrument Control Computer (ICC). This undertaking is both challenging and ambitious; an entire assay system of this type has never been done before in a working facility. This paper will describe, in particular, the effort of the Los Alamos Safeguards Assay Group in this endeavor. Our effort in this project can be roughly divided into three phases: NDA development, system integration, and integral testing. 6 references

Design and fabrication of NDA standards

The Plutonium Facility, TA-55, at Los Alamos National Laboratory is currently producing NDA calibration standards used by various laboratories in the DOE complex. These NIST traceable standards have been produced to calibrate NDA instruments for accountability measurements used for resolving shipper/receiver differences, and for accountability in process residues and process waste. Standards are needed to calibrate various NDA (Non-destructive Assay) instruments such as neutron coincidence counters, gamma-ray counters, and calorimeters. These instruments measure various ranges of nuclear material being produced in the DOE nuclear community. Los Alamos National Laboratory has taken a lead role in fabrication of uranium and plutonium standards, along with other actinides such as neptunium and americium. These standards have been fabricated for several laboratories within the complex. This paper will summarize previous publications detailing the careful planning encompassing components such as precise weighing, destructive analysis, and the use of post fabrication NDA measurements to confirm that the standards meet all preliminary expectations before use in instrument calibration. The paper will also describe the specialized containers, diluents, and the various amount of nuclear materials needed to accommodate the calibration ranges of the instruments

Experience of developing an integrated nondestructive assay system

A consortium of national laboratories is collaborating with the Savannah River Plant to develop an integrated system of state-of-the-art nondestructive assay (NDA) instrumentation to provide nuclear materials accounting and process control information for a new plutonium scrap recovery facility. Individual microcomputer-based instruments report assay results to an instrument control computer (ICC). The ICC, in turn, is part of a larger computer network that includes computers that perform process control and nuclear materials accounting functions. The experience in developing the integrated NDA system, the design, and the testing are discussed

Application of the hybrid x-ray instrument for measurement of thorium-plutonium mixed solutions

The hybrid K-edge densitometry/K-x-ray fluorescence instrument constructed by Kernforschungszentrum Karlsruhe, Federal Republic of Germany, is used to measure Th/Pu mixed solutions. We found that the optimal accelerating voltage for measuring these mixed solutions is 130 kV. At optimum operating conditions, the detection limit for thorium is about 25 mg/l. The minimum Th/Pu ratio that can be assayed by the instrument is about 1/1000

Simulation of x-ray fluorescence spectra

A method for simulating x-ray fluorescence (XRF) spectra in hybrid densitometry is presented. This technique allows simulation of XRF spectra for solutions with arbitrary concentrations of special nuclear material and minor actinides excited by an x-ray generator. Spectra for mixed uranium and plutonium solutions with U/Pu ratios ranging from 100 to 1 have been generated. This range of ratios applies to most solutions found in plutonium reprocessing plants. XRF simulation can provide important data for estimating instrument precision, evaluating analysis techniques, and training system operators. Applications of XRF simulation in the development of the Los Alamos Hybrid K-Edge/XRF Densitometer system are described

Hybrid chemical and nondestructive analysis technique

A hybrid chemical/NDA technique has been applied at the Los Alamos National Laboratory to the assay of plutonium in ion-exchange effluents. Typical effluent solutions contain low concentrations of plutonium and high concentrations of americium. A simple trioctylphosphine oxide (TOPO) separation can remove 99.9% of the americium. The organic phase that contains the separated plutonium can be accurately assayed by monitoring the uranium L x-ray intensities