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in creator/contributor: "Caldwell, J.T."

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Experimental evaluation of the differential die-away pulsed-neutron technique for the fissile assay of hot irradiated fuel waste

Hot irradiated fuel waste packages containing self neutron sources up to 10/sup 7/ n/s may be assayed successfully with a 25-mg /sup 239/Pu detection sensitivity using a differential die-away fissile assay system based on a Sandia-designed 14-MeV neutron generator. With a minor design change, our system can accommodate contact gamma dose rates up to 10/sup 4/ R/h with no loss of fissile assay sensitivity.

Date: January 1, 1982

Creator: Caldwell, J.T. & Kunz, W.E.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Current status of the multi-isotopic transuranic-waste-assay system

We have designed, constructed, tested, and are scheduled to field a 208-l barrel-sized working version of our multi-isotopic transuranic assay system. This system uses both passive neutron multiplicity and pulsed active measurements to identify and quantify spontaneous neutron emitters and fissile TRU isotopes. Using the system we can separately quantify up to seven individual transuranic isotopes under favorable conditions with the intrinsic sensitivity to screen or assay barrels at or below t… more

Date: January 1, 1982

Creator: Kunz, W.E. & Caldwell, J.T.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Mobile nondestructive examination and assay instruments

A compact system that evaluates radioactive materials can furnish a big savings to taxpayers by ensuring that only properly identified nuclear waste is sent to a Department of Energy (DOE) radioactive waste storage area. The Los Alamos National Laboratory's Advanced Nuclear Technology Group has developed and field tested two easily transportable, self-contained modules: one performs real-time radiography of special 208-/l/ shipment containers, the other assays the contents. The examination and … more

Date: January 1, 1988

Creator: Bieri, J.M. & Caldwell, J.T.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Nonintrusive irradiated fuel inventory confirmation technique

Successful tests showing correlation between the intensity of the Cerenkov glow surrounding irradiated fuel assemblies in water-filled spent fuel storage ponds and the exposure and cooling times of assemblies have been concluded. Fieldable instruments used in subsequent tests confirmed that such measurements can be made easily and rapidly, without fuel assembly movement or the introduction of apparatus into the storage ponds.

Date: January 1, 1980

Creator: Dowdy, E.J.; Nicholson, N. & Caldwell, J.T.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Irradiated fuel monitoring by Cerenkov glow intensity measurements

Attribute measurement techniques for confirmation of declared irradiated fuel inventories at nuclear installations under safeguards surveillance are being investigated. High-gain measurements of the intensity of the Cerenkov glow from exposed assemblies in water-filled storage ponds are promising for this purpose. Such measurements have been made of Materials Testing Reactor plate-type fuel assemblies and Pressurized Water Reactor pin-type fuel assemblies. The measured intensities depend on coo… more

Date: September 1, 1979

Creator: Dowdy, E.J.; Nicholson, N. & Caldwell, J.T.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

A l-nCi/g sensitivity transuranic waste assay system using pulsed neutron interrogation

We have developed a pulsed thermal neutron interrogation system and have demonstrated a sub-1-nCi/g assay sensitivity for high density TRU wastes contained in 200-liter barrels. We detect prompt fission neutrons, resulting in greatly enhanced sensitivity compared to techniques in which delayed fission neutrons are detected. We observe a linear assay response over at least three orders of magnitude in /sup 235/U (or /sup 239/Pu) mass. We also have measured a flat (to +-10%) interrogation flux pr… more

Date: January 1, 1980

Creator: Kunz, W.E.; Atencio, J.D. & Caldwell, J.T.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Survey of DOE NDA practices for CH-Tru waste certification--illustrated with a greater than 10,000 drum NDA data base

We have compiled a greater than 10,000 CH-TRU waste drum data base from seven DOE sites which have utilized such multiple NDA measurements within the past few years. Most of these nondestructive assay (NDA) technique assay result comparisons have been performed on well-characterized, segregated waste categories such as cemented sludges, combustibles, metals, graphite residues, glasses, etc., with well-known plutonium isotopic compositions. Waste segregation and categorization practices vary fro… more

Date: January 1, 1988

Creator: Schultz, F. J.; Caldwell, J. T. & Smith, J. R.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Prompt and delayed neutron yields from low energy photofission of $sup 232$Th, $sup 235$U, $sup 238$U, and $sup 239$Pu

No Description Available.

Date: January 1, 1973

Creator: Caldwell, J.T.; Dowdy, E.J. & Worth, G.M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Criticality calculations and criticality monitoring studies of the slagging pyrolysis incinerator facility

It was determined that the criticality hazard associated with the Slagging Pyrolysis Incinerator (SPI) Facility would be minimal if a three-level criticality-hazard prevention program were implemented. The first strategy consists of screening all incoming wastes for fissile content. The second prevention level is provided by introducing a small concentration of a neutron-absorbing compound, such as B/sub 2/O/sub 3/, into the input waste stream. The third prevention level is provided by direct c… more

Date: January 1, 1981

Creator: Close, D. A.; Booth, T. E. & Caldwell, J. T.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Measurement of radioactive contaminated wastes

At Los Alamos, a comprehensive program is underway for the development of sensitive, practical, nondestructive assay techniques for the quantification of low-level transuranics in bulk solid wastes. The program encompasses a broad range of techniques, including sophisticated active and passive gamma-ray spectroscopy, passive neutron detection systems, pulsed portable neutron generator interrogation systems, and electron accelerator-based techniques. The techniques can be used with either low-le… more

Date: January 1, 1983

Creator: Caldwell, J. T.; Close, D. A. & Crane, T. W.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Survey of special nuclear material vehicle monitors for domestic and international safeguards

Special nuclear materials vehicle monitors, including gateside vehicle monitors, hand-held personnel-vehicle monitors, and a new tunnel monitor concept for very large vehicles, are discussed. The results of a comparison of effectiveness of monitors for domestic application are presented. The results of calculations and small scale prototype measurements are given for a tunnel-like neutron monitor for monitoring at the perimeter of an enrichment plant subjected to International Safeguards.

Date: January 1, 1979

Creator: Fehlau, P. E.; Atwater, H. F.; Caldwell, J. T. & Shunk, E. R.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

High-efficiency, modular system for the assay of plutonium in large waste packages

A 4..pi.. coincidence neutron counting system with nominal assay chamber dimensions of 1.2 by 1.2 by 2.4 m and a 14% detection efficiency has been designed constructed, and used to determine the plutonium content in large crates of miscellaneous nuclear waste.

Date: January 1, 1981

Creator: Shunk, E.R.; Caldwell, J.T.; France, S.W. & Herrera, G.C.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

$sup 235$U enrichment determination using $sup 4$He proportional counters

Two independent techniques ---one passive and one active ---for determining /sup 235/U enrichment in UF/sub 6/ have been developed utilizing /sup 4/He proportional counters. Enrichment value precisions with both techniques on the order of 3- to 5-% have been demonstrated during three field trials at the Oak Ridge and Goodyear Atomic Gaseous Diffusion Plants. With the prototype system used during field trials statistical precisions of better than 2% were obtained for typical type 30 and 48 UF/su… more

Date: January 1, 1973

Creator: Caldwell, J. T.; Evans, J. L.; Fehlau, P. E. & Whittlesey, T. H.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Large vehicle portal monitor for perimeter safeguards applications

We have developed a class of vehicle portal monitors based on shielded 4..pi.. geometry neutron counting. we have derived and experimentally verified an analytical expression relating the detection sensitivity of the neutron tunnel vehicle portal monitor to four design parameters of the system. For a given number of neutron detectors, this design achieves one or more orders of magnitude improvement in nuclear materials detection sensitivity over previous vehicle portal monitors.

Date: January 1, 1979

Creator: Caldwell, J.T.; Atwater, H.F.; Bernard, W.; Bieri, J.M. & Shunk, E.R.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Making transuranic assay measurements using modern controllers

This paper describes methodology and computer-controlled instrumentation developed at the Los Alamos National Laboratory that accurately performs nondestructive assays of large containers bearing transuranic wastes and nonradioactive matrix materials. These assay systems can measure fissile isotopes with 1-mg sensitivity and spontaneous neutron-emitting isotopes at a 10-mg sensitivity. The assays are performed by neutron interrogation, detection, and counting in a custom assay chamber. An Inter… more

Date: January 1, 1987

Creator: Kuckertz, T.H.; Caldwell, J.T.; Medvick, P.A.; Kunz, W.E. & Hastings, R.D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

High-sensitivity transuranic waste assay by simultaneous proton and thermal-neutron interrogation using an electron linear accelerator

Simultaneous photon and neutron interrogation from electron linear accelerator pulses is used as the basis for a unique assay technique for transuranics. Both prompt and delayed neutrons from the induced fissions are counted on a single detection system, and the contributions from each interrogating flux are resolved. Detection limits (3 sigma) for /sup 239/Pu were estimated to be 3 mg for prompt fission neutrons and 6 mg for delayed neutrons. The technique also provides a clear distinction bet… more

Date: January 1, 1982

Creator: Franks, L. A.; Pigg, J. L.; Caldwell, J. T.; Cates, M. R.; Kunz, W. E. & Noel, B. W.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Multi-isotopic gamma-ray assay system for alpha-contaminated waste

The capability of an existing segmented gamma-ray system is being expanded for the analysis of alpha-contaminated waste drums. A cursory assay of 114 transuranic waste drums of 208-l capacity has been made. Analysis of these data indicates a detection limit better than 100 nCi/g of waste for /sup 237/Np//sup 233/Pa, /sup 239/Pu, /sup 241/Am, /sup 243/Am//sup 239/Np, /sup 60/Co, /sup 125/Sb, /sup 134/ /sup 137/Cs, and /sup 154/Eu. A pending Code of Federal Regulation (10CFR61) stipulates that th… more

Date: January 1, 1983

Creator: Close, D. A.; Pratt, J. C.; Caldwell, J. T.; Kunz, W. E.; Schultz, F. J. & Haff, K. W.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Rapid fuel drawer scanner for fast critical assembly safeguards

An integrated scanning system incorporating highly efficient collimated neutron and high purity germanium gamma detectors with an on-line microprocessor has been developed to perform rapid inventorying of uranium and plutonium fuel drawers from fast critical assemblies. On-line least-squares fit procedures provide quantitative comparisons at a rate exceeding two drawers per minute. For plutonium-containing fuel, the neutron scan data can be related to the included /sup 240/Pu isotopic mass; ind… more

Date: January 1, 1980

Creator: Pratt, J. C.; France, S. W.; Hsu, H. H.; Caldwell, J. T.; Hastings, R. D. & Shunk, E. R.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Evaluation of sealed-tube neutron generators for the assay of fresh LWR fuel assemblies

The use of sealed-tube neutron generators for the active assay of fresh light-water reactor fuel assemblies has been investigated. The results of experimental tests of the Kaman 801 generator are presented. Neutron yields, source moderation, and transportability are discussed. A comparison is made with the AmLi neutron source for use in the Coincidence Collar.

Date: November 1, 1981

Creator: Cutter, J.; Lee, D.; Lindquist, L. O.; Menlove, H. O.; Caldwell, J. T.; Atencio, J. D. et al.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Electron accelerator based system for assay of transuranic waste barrels

A complete assay system for 208-liter barrels contianing transuranic wastes has been developed. The system consists of an 8-MeV commercial electron accelerator, neutron moderating cavity housing the waste barrel and containing neutron detectors, high resolution germanium gamma spectrometer, and x-ray radiography camera (both film and real time). The electron linac is used to produce bremsstrahlung and high-intensity pulsed neutron flux, both of which are used to interrogate the fissionable mate… more

Date: January 1, 1984

Creator: Kocimski, S. M.; Franks, L. A.; Caldwell, J. T.; Close, D. A.; Kunz, W. E.; Morgado, R. E. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Application of linear accelerator technology to the detection of trace amounts of transuranics in waste barrels

Electron linear accelerators (linacs), as sources of photons and neutrons, can produce a significant number of fissions in transuranic isotopes contained in large barrels of waste material. Both photons and thermal neutrons have been used to detect about 1 mg of plutonium in 105-kg matrices. A sequential interrogation with neutrons and photons, easily possible with linacs, can show both fertile and fissile constituents among the heavy-mass isotopes. The advantages of linacs in solving existing … more

Date: January 1, 1980

Creator: Cates, M. R.; Noel, B. W.; Caldwell, J. T.; Kunz, W. E.; Close, D. A.; Franks, L. A. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

ORNL TRU-waste-assay system

ORNL has been selected as the demonstration site for a new transuranic neutron assay system developed at the Los Alamos National Laboratory. The major objectives of the cooperative interlaboratory program is to field test, calibrate, and evaluate the neutron interrogation system, to provide a demonstration and training facility for DOE of this sophisticated technology, to reduce the volume of TRU waste stored at ORNL, and to provide positive identification of the radionuclide content of the ORN… more

Date: January 1, 1983

Creator: Schultz, F. J.; Haff, K. W.; Caldwell, J. T.; Close, D. A.; Kuckertz, T. H.; Kunz, W. E. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Test and evaluation of a high-sensitivity assay system for bulk transuranic waste

During the past year, we tested and evaluated the performance of an assay system that accommodates 55-gal drums of transuranic waste at Oak Ridge National Laboratory. This neutron assay system provides a routine assay of fissile transuranic isotopes to the 1-mg sensitivity level with a pulsed active neutron interrogation based on the differential dieaway technique. A highly sensitive passive neutron measurement determines the content of spontaneous fission transuranic isotopes in each drum as w… more

Date: January 1, 1983

Creator: Caldwell, J. T.; Close, D. A.; Kuckertz, T. H.; Kunz, W. E.; Pratt, J. C.; Haff, K. W. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

ORNL TRU waste assay system

ORNL has been selected as the demonstration site for a new transuranic neutron assay system developed at the Los Alamos National Laboratory. The major objectives of the cooperative interlaboratory program are to field test, calibrate, and evaluate the neutron interrogation system, to provide a demonstration and training facility for personnel from other DOE sites and contractors, to reduce the volume of TRU waste stored at ORNL, and to provide positive identification of the radionuclide content… more

Date: January 1, 1983

Creator: Schultz, F. J.; Haff, K. W.; Caldwell, J. T.; Close, D. A.; Kuckertz, T. H.; Kunz, W. E. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department