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Moss, Calvin Elroy

Publications and source records attributed to Moss, Calvin Elroy.

7 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

COMET/ZEUS Activation Foils Report for Irradiations IER-241 and IER-261

The goal of this work was to determine the internal neutron spectrum of the COMET/ZEUS assembly using activation foils. Similar measurements were performed on the COMET assembly when it was located at the Los Alamos Critical Experiments Facility (LACEF) at the Los Alamos National Laboratory (LANL). The present measurements were performed after the COMET assembly was moved to the National Criticality Experiments Research Center (NCERC) located in the Device Assembly Facility (DAF) at the Nevada National Security Site (NNSS). The December 2012 COMET/ZEUS irradiation was the first in a series of experiments, and the COMET/ZEUS assembly was selected because of operational readiness and authorization to run specific targets. The August 2013 irradiation was the second in the series and involved only small changes in the configuration. This report describes the unfolding of the activation foils to determine the internal neutron spectra.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2019

ZEUS Activation Foils Report for Experiments 1-5

The ZEUS experiments were conducted using the COMET vertical assembly machine at the Los Alamos Critical Experiments Facility (LACEF) at the Los Alamos National Laboratory (LANL). The experiments were designed to check the adequacy of cross sections in the intermediate-energy range. For the first four experiments, 12 kg highly enriched uranium (HEU) layers were sandwiched between different numbers of graphite plates in a vertical stack. In the first four experiments, a unit cell consisted of n graphite plates, an HEU layer, and then another n graphite plates. The unit cells were stacked until criticality was obtained. Experiments 1, 2, 3, and 4 contained decreasing amounts of graphite, where the unit cells value n was 4, 3, 2 and 1 respectively. In experiment 5 the HEU plates were in direct contact with each other to evaluate cross sections in the fast-energy range. A detailed description of experiments 1-4 is provided in reference, and of experiment 5, in reference. In order to investigate the cross sections in more detail, some ZEUS runs were made with activation foils inside the assemblies. Ratios of the activations of various foils are a standard method of measuring the gross neutron spectrum shape. A more detailed spectrum can be determined by simultaneously unfolding the response of several foils. This report describes the unfolding of the ZEUS activation foils data. The focus in this analysis is on the fast-energy range, especially at > 5 MeV.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2018

Momentum Users Guide

Momentum is software, written Mark Smith-Nelson, to analyze neutron list-mode data. It contains some features specific to the MC-15 and NPOD neutron multiplicity counters. The MC-15 contains 15 3 He tubes and electronics for recording, in list mode, the time and tube number for each neutron detection. The data depends on many different parameters, including the source material type, source mass and enrichment, alpha ratio, detection efficiency, and multiplication. If some minimum number of these parameters is known, then Momentum can be used to calculate the remaining parameters.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2018

MC-15 Users Manual

The current iteration of field -capable neutron multiplicity counters is the Multiplicity Counter 15 tube detector (MC-15) shown in Figure 1. This was a tri-lab effort between Los Alamos National Laboratory (LANL), Lawrence Livermore National Laboratory (LLNL), and Sandia National Laboratories (SNL). The MC-15 incorporates significant improvements over previous man-portable neutron multiplicity counters of the LANL NPOD and the Ortec Fission Meter™. These improvements include finer time resolution of 100 ns, more advanced on-board computing power for near-real-time onboard analysis, a sunlight readable color touchscreen for ease of use, a USB 2.0 interface for data transfer, and hot-swappable rechargeable batteries that provide 14 hours of run time.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2017

Revised SNAP III Training Manual

The Shielded Neutron Assay Probe (SNAP) technique was developed to determine the leakage neutron source strength of a radioactive object. The original system consisted of an Eberline TM Mini-scaler and discrete neutron detector. The system was operated by obtaining the count rate with the Eberline TM instrument, determining the absolute efficiency from a graph, and calculating the neutron source strength by hand. In 2003 the SNAP III, shown in Figure 1, was designed and built. It required the operator to position the SNAP, and then measure the source-to-detector and detectorto- reflector distances. Next the operator entered the distance measurements and started the data acquisition. The SNAP acquired the required count rate and then calculated and displayed the leakage neutron source strength (NSS). The original design of the SNAP III is described in SNAP III Training Manual (ER-TRN-PLN-0258, Rev. 0, January 2004, prepared by William Baird) This report describes some changes that have been made to the SNAP III. One important change is the addition of a LEMO connector to provide neutron detection output pulses for input to the MC-15. This feature is useful in active interrogation with a neutron generator because the MC-15 has the capability to only record data when it is not gated off by a pulse from the neutron generator. This avoids recording of a lot of data during the generator pulses that are not useful. Another change was the replacement of the infrared RS-232 serial communication output by a similar output via a 4-pin LEMO connector. The current document includes a more complete explanation of how to estimate the amount of moderation around a neutron-emitting source.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2017

Survey of Neutron Generators for Active Interrogation

Some of these commercially available generators meet all of the requirements in Table 1, but there are other concerns. Most generators containing SF6 will be required to have the SF6 gas removed for shipping because of DOT regulations. However, Thermo Fisher has a DOT exemption. The P211 and B211 from Thermo Fisher meet the requirements listed in Table 1, but they are old designs and are no longer offered for sale. Also, they require 15 minutes or more of warmup before neutron output is available, and they lack a modern digital control. The nGen-300C from Starfire Industries is interesting because it is a portable system, but it uses the DD reaction for 2.5 MeV neutrons, which are not as penetrating as the 14 MeV neutrons from the DT reaction. The MP 320 from Thermo Fisher is another portable system, but the minimum pulse rate is 250 Hz, which is too fast for measurement of delayed neutrons and re-interrogation by delayed neutrons between pulses. The Genie 16 from Sodern (from France) probably meets the requirements, but the required power is probably too high for battery operation. The generators from Russia and China may be difficult to purchase, and service may not be available. The power required by some of these generators is low enough that batteries can be used. The portable units, nGen-300C and the MP320, could easily be operated with batteries. Other generators with low power requirements, as specified in the above vendors list, could possibly be operated with reason size batteries. The batteries do not need to be internal to the generator, but can be in a separate package. The availability of high capacity lithium batteries with sophisticated safety circuits makes battery operation more possible now than when lead acid batteries were used. The best path forward probably requires working with vendors of the existing systems. If Starfire Industries could be persuaded to put tritium in their nGen-300C generator, possibly in collaboration with a national laboratory, this would provide the 14-MeV neutrons needed. Another possibility is a modification of the Thermo Fisher MP 320 to run at 50 to 100 Hz. More discussions with these vendors, and possibly others, are required to determine their interest and possible costs.

43 PARTICLE ACCELERATORS↗