[en] A brief review is given of internal friction relaxation peaks and background internal friction. The microstructural origin of the internal friction is discussed. Particular emphasis is placed on radiation effects

[en] Differential and total displacement and helium production rates are calculated for copper irradiated by spallation neutrons and 760 MeV protons at LAMPF. The calculations are performed using the SPECTER and VNMTC computer codes, the latter being specially designed for spallation radiation damage calculations. For comparison, similar SPECTER calculations are also described for irradiation of copper in EBR-II and RTNS-II. The results indicate substantial contributions to the displacement and helium production rates due to neutrons in the high-energy tail (above 40 MeV) of the LAMPF spallation neutron spectrum. Still higher production rates are calculated for irradiations in the direct proton beam. These results will provide useful background information for research to be conducted at a new irradiation facility at LAMPF

[en] A ''rabbit'' system has been installed in an insert at the Los Alamos Spallation Radiation Effects Facility (LASREF). Spallation neutrons at LASREF are produced by the passage of the LAMPF 800-MeV proton beam through the Isotope Production (IP) targets and into the beam stop. This dosimetry insert allows measurement of the spallation neutron and secondary proton fluxes and energy spectra in any of the 12 neutron irradiation locations. Four ''rabbit'' tubes allow radial measurements at 0.12, 0.18, 0.27, and 0.38 meters off beam centerline. Aluminum capsules (''rabbits'') are used to hold the activation foils. As many as five capsules can be stacked on top of one another in each tube to allow measurements below, on, and above beam centerline. Thirteen multiple-foil activation experiments were done at these two locations. Neutron spectra were similar with the exception of the reduction of the high-energy tail outside the beam stop. The spectra outside the beam stop for eight and zero IP targets were similar in spectral shape but reduced in magnitude by a factor of two when eight IP targets were inserted into the proton beam. Measurements showed no difference in the flux below, on, or above beam centerline. With respect to the radial variation in the flux, measurements showed similar spectral shapes between the first three tubes. The fourth tube showed an enhancement in the 24-keV region due to the transmission window in the iron cross section. The ''rabbit'' system is available for use by experimenters at LASREF

[en] Foil activation dosimetry experiments were conducted in a ''rabbit'' system at the completed Los Alamos Spallation Radiation Effects Facility (LASREF). The ''raffit'' system contains four tubes spaced radially outward 0.12, 0.18, 0.27, and 0.38 meters off beam centerline. Foils were irradiated for 3 to 62 hours to measure the neutron flux and energy spectrum radially from beam centerline, along the beamline, and the effect of the Isotope Production (IP) target loadings on the neutron flux in the neutron irradiation locations. Irradiations showed a decrease in the radial flux by a factor of 6 in 0.15 meters of iron outside the IP targets. An enchancement was seen in the 24-keV energy region outside 0.15 meters. There was little difference in the shape of the spectra outside the IP targets and the beam stop with the exception of the high energy tail (energies above 20 MeV). The decrease in the high energy tail outside the beam stop is due to the degradation of the energy of the proton beam in the IP targets. Irradiations outside the beam stop with zero and eight IP targets gave the same spectral shape with the exception of the high energy tail. The magnitude of the integral flux decreased by a factor of 2 when eight IP targets were present. Irradiations with five ''rabbits'' stacked on top of each other showed no difference in the integral flux below, on and above beam centerline

[en] A foil activation dosimetry experiment was conducted at the LAMPF beam-stop area to characterize the radiation environment and to identify techniques for spallation radiation measurements. Foils were irradiated for approx.8 weeks in the primary proton beam and in the spallation neutron flux in isotope production stringer 5. The STAY'SL computer code was used to determine the most probable spectrum, considering the measured activities, the input spectrum, and the activation cross sections

[en] Differential and total displacement and helium-production rates are calculated for copper irradiated by spallation neutrons and 760-MeV protons at LAMPF. The calculations are performed using the SPECTOR and VNMTC computer codes, the latter being specially designed for spallation radiation-damage calculations. For comparison, similar SPECTER calculations are also described for irradiation of copper in the experimental breeder reactor (EBR-II) at the Argonne National Laboratory-West in Idaho, and in the rotating target neutron source (RTNS-II) at Lawrence Livermore Laboratory. The neutron energy spectra for LAMPF, EBR-II, and RTNS-II and the displacement and helium-production cross sections are shown

[en] Measurements have been made at the Los Alamos National Laboratory (LANL) in the US and the Power Reactor Nuclear Fuel Development Corporation/Plutonium Fuel Production Facility (PNC/PFPF) in Japan with the Passive Neutron Waste Assay System (JCC-21) employing the Add-a-Source technique to quantify the plutonium content in 208 liter drums. The JCC-21 was jointly developed by Canberra Nuclear and LANL. High counting efficiency is obtained by using multiple ³He detectors in a 4π geometry, and a carefully-designed high-density polyethylene moderator provides relative insensitivity to the effects of scattering reactions in the matrix. Additional high-density polyethylene also provides shielding to reduce the low-energy ambient neutron background and improves the detection limit. The Add-a-Source technique developed by LANL provides a significant improvement in accounting for matrix effects by actually measuring the matrix absorption of neutrons from a small ²⁵²Cf source and correcting the detected flux for the matrix absorption. Matrix effects and corrections using the Add-a-Source technique were evaluated during installation. A detectability limit of 0.73 mg ²⁴⁰Pu_eff was measured for coincidence count at PNC/PFPF, making the JCC-21 one of the most sensitive and accurate NDA systems for analysis of plutonium-bearing waste. A detectability limit of 0.4 mg ²⁴⁰Pu_eff was measured for total counts at LANL, demonstrating a lower detection limit for waste where the (α,n) component is known. Enhancements to the counter design are being investigated to improve the sensitivity by reducing the background and increasing the counting efficiency. New counting techniques are also being investigated to improve the accuracy of the assay. The results of these enhancements and new techniques are presented

[en] CT: A foil activation dosimetry experiment was conducted at the Clinton P. Anderson Los Alamos Meson Physics Facility (LAMPF) beam stop area to characterize the radiation environment and to identify techniques for spallation radiation measurements. The measured total spallation neutron flux outside the primary proton beam was 5.5 X 10¹⁷ neutrons/m²/5/mA + or - 7%. A previous Monte Carlo calculation gave a total spallation neutron flux in approximately the same location as the dosimetry package of 6.0 X 10¹⁷ neutrons/m²/5/mA + or - 3%. Comparison between the measured and calculated neutron fluxes shows good agreement. To extend the characterization, additional spallation cross sections for energies up to 800 MeV and the use of foils sensitive to the epithermal energy range are needed

[en] CT: Differential and total displacement and helium production rates are calculated for copper irradiated by spallation neutrons and 760 MeV protons at the Clinton P. Anderson Los Alamos Meson Physics Facility (LAMPF). The calculations are performed using the SPECTER and VNMTC computer codes, the latter being specially designed for spallation radiation damage calculations. For comparison, similar SPECTER calculations are also described for irradiation of copper in EBR-II and RTNS-II. The results indicate substantial contributions to the displacement and helium production rates due to neutrons in the high-energy tail (above 20 MeV) of the LAMPF spallation neutron spectrum. Still higher production rates are calculated for irradiations in the direct proton beam. These results will provide useful background information for research to be conducted at a new irradiation facility at LAMPF

[en] Non-Destructive Assay for safeguards and waste applications requires accurate determination of the Pu and U content of the samples. NDA systems must be designed to handle a variety of sample sizes, chemical forms, isotopics and matrices, all of which complicate the analysis of the measurement data. Canberra has evaluated regulatory requirements and nuclear material types worldwide to identify a standard set of NDA instruments that address these diversified applications. As these systems are becoming more common, the need for verification and certification of their performance for various sample types increases. Performance data for most of Canberra's safeguards and waste have been published in recent years. Canberra has combined all of these data into a composite evaluation of the total measurement uncertainty (TMU). This paper includes a summary of these TMU and each of the components that produce this overall uncertainty for two standard NDA systems: Waste Drum Assay Systems and the Waste Assay Scanner. This approach for determining the TMU for an assay has been accepted by the US Department of Energy and the approach has been implemented in Canberra's standard neutron and gamma NDA software. Also, the major contributors to the TMU have been identified and new assay techniques have been identified to detect and minimize the TMU. (author)