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All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Current Status of Helium-3 Alternative Technologies for Nuclear Safeguards

International safeguards inspectorates (e.g., International Atomic Energy Agency {IAEA}, or Euratom) rely heavily on neutron assay techniques, and in particular, on coincidence counters for the verification of declared nuclear materials under safeguards and for monitoring purposes. While 3 He was readily available, the reliability, safety, ease of use, gamma-ray insensitivity, and high intrinsic thermal neutron detection efficiency of 3 He-based detectors obviated the need for alternative detector technologies. However, the recent decline of the 3 He gas supply has triggered international efforts to develop and field neutron detectors that make use of alternative materials. In response to this global effort, the U.S. Department of Energy’s (DOE) National Nuclear Security Administration (NNSA) and Euratom launched a joint effort aimed at bringing together international experts, technology users and developers in the field of nuclear safeguards to discuss and evaluate the proposed 3 He alternative materials and technologies. The effort involved a series of two workshops focused on detailed overviews and viability assessments of various 3 He alternative technologies for use in nuclear safeguards applications. The key objective was to provide a platform for collaborative discussions and technical presentations organized in a compact, workshop-like format to stimulate interactions among the participants. The meetings culminated in a benchmark exercise providing a unique opportunity for the first inter-comparison of several available alternative technologies. This report provides an overview of the alternative technology efforts presented during the two workshops along with a summary of the benchmarking activities and results. The workshop recommendations and key consensus observations are discussed in the report, and used to outline a proposed path forward and future needs foreseeable in the area of 3 He-alternative technologies.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2013

Alternatives for Helium-3 in Multiplicity Counters

Alternatives to helium-3 are being actively pursued due to the shortage and rising costs of helium-3. For safeguards applications, there are a number of ongoing investigations to find alternatives that provide the same capability in a cost-effective manner. One of the greatest challenges is to find a comparable alternative for multiplicity counters, since they require high efficiency and short collection or die-away times. Work has been progressing on investigating three commercially available alternatives for high efficiency multiplicity counters: boron trifluoride (BF3) filled proportional tubes, boron-lined proportional tubes, and lithium fluoride with zinc sulfide coated light guides. The baseline multiplicity counter used for the investigation is the Epithermal Neutron Multiplicity Counter with 121 helium-3 filled tubes at 10 atmosphere pressure, which is a significant capability to match. The primary tool for the investigation has been modeling and simulation using the Monte Carlo N-Particle eXtended (MCNPX) radiation transport program, with experiments to validate the models. To directly calculate the coincidence rates in boron-lined (and possibly other) detectors, the MCNPX code has been enhanced to allow the existing coincidence tally to be used with energy deposition rather than neutron capture reactions. This allows boron-lined detectors to be modeled more accurately. Variations of tube number and diameter along with variations in the amount of inter-tube moderator have been conducted for the BF3 and boron-lined cases. Tube pressure was investigated for BF3, up to two atmospheres, as well as optimal boron thickness in the boron-lined tubes. The lithium fluoride was modeled as sheets of material with light guides in between, and the number and thickness of the sheets investigated. The amount of light guide, which in this case doubles as a moderator, was also optimized. The results of these modeling and simulation optimization investigations are described and results presented.

Ely, James H.↗
DOE OSTI2012

Alternatives to Helium-3 for Neutron Multiplicity Counters

Multiplicity counters are an example of a neutron detection system affected by the shortage of 3He. Efforts are underway to identify potential 3He neutron detector replacements for use in multiplicity counters. Boron-10 and 6Li based systems are two of the options being explored as near-term 3He alternatives for neutron multiplicity counters. Simulations of BF3, 10B-lined proportional counters and 6Li/ZnS(Ag) sheets in various configurations have been performed with the Monte Carlo particle transport code MCNPX and compared to simulations of existing 3He counters. The system performances are being compared using figure of merits that are the square or cube of the total system efficiency divided by the die-away time. Design considerations include developing a system with enough neutron detection material to achieve the highest possible efficiency, while simultaneously minimizing system size. Adequate moderation is required to thermalize the incident neutrons for increased counting efficiency but as the system size increases so will the die-away time (average lifetime of neutrons in the counter). The optimal moderator configuration is one for which the increase in neutron detection efficiency is not defeated by an increase in die-away time. Thus, the entire system performance must be evaluated with every configuration change. The simulation results will be validated against a bench-top demonstrator unit design based on the system identified through simulations as having the highest performance potential. Presented here are the simulation results with various configurations of BF3 filled proportional counters, 10B lined proportional counters and 6Li/ZnS(Ag) sheets, and preliminary bench-top measurements.

Alternatives to Helium-3 for Neutron Multiplicity ↗
DOE OSTI2012

ALTERNATIVES TO HELIUM-3 FOR NEUTRON MULTIPLICITY DETECTORS

Collaboration between the Pacific Northwest National Laboratory (PNNL) and the Los Alamos National Laboratory (LANL) is underway to evaluate neutron detection technologies that might replace the high-pressure helium (3He) tubes currently used in neutron multiplicity counter for safeguards applications. The current stockpile of 3He is diminishing and alternatives are needed for a variety of neutron detection applications including multiplicity counters. The first phase of this investigation uses a series of Monte Carlo calculations to simulate the performance of an existing neutron multiplicity counter configuration by replacing the 3He tubes in a model for that counter with candidate alternative technologies. These alternative technologies are initially placed in approximately the same configuration as the 3He tubes to establish a reference level of performance against the 3He-based system. After these reference-level results are established, the configurations of the alternative models will be further modified for performance optimization. The 3He model for these simulations is the one used by LANL to develop and benchmark the Epithermal Neutron Multiplicity Counter (ENMC) detector, as documented by H.O. Menlove, et al. in the 2004 LANL report LA-14088. The alternative technologies being evaluated are the boron-tri-fluoride-filled proportional tubes, boron-lined tubes, and lithium coated materials previously tested as possible replacements in portal monitor screening applications, as documented by R.T. Kouzes, et al. in the 2010 PNNL report PNNL-72544 and NIM A 623 (2010) 1035–1045. The models and methods used for these comparative calculations will be described and preliminary results shown

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2014

Plutonium measurements with a fast-neutron multiplicity counter for nuclear safeguards applications

Measurements were performed at the Joint Research Centre in Ispra, Italy to field test a fast-neutron multiplicity counter developed at the University of Michigan. The measurements allowed the assessment of the system's photon discrimination abilities, efficiency when measuring neutron multiplicity, ability to characterize 240 Pu eff mass, and performance relative to a currently deployed neutron coincidence counter. We describe how this work is motivated by the need to replace and improve upon 3 He neutron detection systems for nuclear safeguards applications.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2013

Cytotoxicity, genotoxicity, and mutagenicity of 1-chloro-2-hydroxy-3-butene and 1-chloro-3-buten-2-one, two alternative metabolites of 1,3-butadiene

The cytotoxicity, genotoxicity, and mutagenicity of 1-chloro-2-hydroxy-3-butene (CHB), a known in vitro metabolite of the human carcinogen 1,3-butadiene, have not previously been investigated. Because CHB can be bioactivated by alcohol dehydrogenases to yield 1-chloro-3-buten-2-one (CBO), a bifunctional alkylating agent that caused globin-chain cross-links in erythrocytes, in the present study we investigated the cytotoxic and genotoxic potential of CHB and CBO in human normal hepatocyte L02 cells using the MTT assay, the relative cloning efficiency assay and the comet assay. We also investigated the mutagenic potential of these compounds with the Ames test using Salmonella strains TA1535 and TA1537. The results provide clear evidence for CHB and CBO being both cytotoxic and genotoxic with CBO being approximately 100-fold more potent than CHB. Interestingly, CHB generated both single-strand breaks and alkali-labile sites on DNA, whereas CBO produced only alkali-labile sites. CHB did not directly result in DNA breaks, whereas CBO was capable of directly generating breaks on DNA. Interestingly, both compounds did not induce DNA cross-links as examined by the comet assay. The Ames test results showed that CHB induced point mutation but not frameshift mutation, whereas the toxic effects of CBO made it difficult to reliably assess the mutagenic potential of CBO in the two strains. Collectively, the results suggest that CHB and CBO may play a role in the mutagenicity and carcinogenicity of 1,3-butadiene. - Highlights: • 1-Chloro-2-hydroxy-3-butene (CHB) is cytotoxic and genotoxic in human liver cells. • The CHB metabolite, 1-chloro-3-buten-2-one (CBO) is ∼ 100-fold more toxic than CHB. • CHB and CBO cause DNA alkali-labile sites, but only CBO directly causes DNA breaks. • CHB is mutagenic in the Ames test, but CBO is too toxic in the assay. • The results suggest a role for CHB in 1,3-butadiene genotoxicity and mutagenicity.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2014

Boron-10 Based Neutron Coincidence Counter for Safeguards

The shortage of 3He has triggered the search for effective alternative neutron detection technologies for national security applications, including international nuclear safeguards. Any alternative neutron detection technology must satisfy two basic criteria: it must meet a neutron detection efficiency requirement, and it must be insensitive to gamma-ray interference at a prescribed level while still meeting the neutron detection requirement. For nuclear safeguards, a system must perform measurements in the field with a prescribed precision in a specified time. This paper describes an effort to design, model and test an alternatives-based neutron coincidence counter for nuclear safeguards applications. The technology chosen for use in an alternatives-based uranium neutron coincidence collar was boron-lined proportional counters. Extensive modeling was performed of various system configurations and comparisons were made to measurements on a commercial prototype boron-10 based uranium neutron coincidence collar.

alternative neutron detectors↗
DOE OSTI2013

Boron-10 ABUNCL Active Testing

The Department of Energy Office of Nuclear Safeguards and Security (NA-241) is supporting the project Coincidence Counting With Boron-Based Alternative Neutron Detection Technology at Pacific Northwest National Laboratory (PNNL) for the development of a 3 He proportional counter alternative neutron coincidence counter. The goal of this project is to design, build and demonstrate a system based upon 10 B-lined proportional tubes in a configuration typical for 3 He-based coincidence counter applications. This report provides results from testing of the active mode of the General Electric Reuter-Stokes Alternative Boron-Based Uranium Neutron Coincidence Collar (ABUNCL) at Los Alamos National Laboratory using sources and fuel pins.

Boron Based Detector↗
DOE OSTI2012

Boron-10 Lined Proportional Counter Wall Effects

The Department of Energy Office of Nuclear Safeguards (NA-241) is supporting the project 'Coincidence Counting With Boron-Based Alternative Neutron Detection Technology' at Pacific Northwest National Laboratory (PNNL) for development of an alternative neutron coincidence counter. The goal of this project is to design, build and demonstrate a boron-lined proportional tube based system in the configuration of a coincidence counter. This report provides information about how variations in proportional counter radius and gas pressure in a typical coincident counter design might affect the observed signal from boron-lined tubes. A discussion comparing tubes to parallel plate counters is also included.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Final Technical Report for the Neutron Detection without Helium-3 Project

This report details the results of the research and development work accomplished for the ‘Neutron Detection without Helium-3’ project conducted during the 2011-2013 fiscal years. The primary focus of the project was to investigate commercially available technologies that might be used in safeguards applications in the relatively near term. Other technologies that are being developed may be more applicable in the future, but were outside the scope of this study.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
NASA NTRS1983

Ordered pairing in liquid metallic hydrogen

We study two possible types of pairing involving the protons of a proposed low-temperature liquid phase metallic hydrogen. Electron-proton pairing, which can result in an insulating phase, is investigated by using an approximate solution of an Eliashberg-type equation for the anomalous self-energy. A very low estimate of the transition temperature is obtained by including proton correlations in the effective interaction. For proton-proton pairing, we derive a new proton pair potential based on the Abrikosov wave function. This potential includes the electron-proton interaction to all orders and has a much larger well depth than is obtained with linear screening methods. This suggests the possibility of either a superfluid paired phase analogous to that in He-3, or alternatively a phase with true molecular pairing.

Carlsson, A. E.↗
DOE OSTI2012

Passive Measurement of Organic-Scintillator Neutron Signatures for Nuclear Safeguards Applications

At nuclear facilities, domestically and internationally, most measurement systems used for nuclear materials’ control and accountability rely on He-3 detectors. Due to resource shortages, alternatives to He-3 systems are needed. This paper presents preliminary simulation and experimental efforts to develop a fast-neutron-multiplicity counter based on liquid organic scintillators. This mission also provides the opportunity to broaden the capabilities of such safeguards measurement systems to improve current neutron-multiplicity techniques and expand the scope to encompass advanced nuclear fuels.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
NASA NTRS1946

Tank Tests of an Alternate Hull Form for the Consolidated Vultee PB2Y-3 Airplane

Tests have been made in Langley tank no. I of a dynamic model of the Consolidated Vultee PB2Y-3 airplane. These tests were made using an alternate hull form, the purpose of which was to reduce the bow spray and eliminate the landing instability which are objectionable features of the production design. The major differences from the PB2Y-3 hull included a deeper step to improve the landing stability , and a lengthened forebody and increased beam to reduce the sway in the propellers and on the flaps. The tests showed that the spray characteristics of the revised hull form were much better than that ot the production design. In addition the take-off and landing stability of the model with the alternate hull were satisfactory.

Land, Norman S.↗
DOE OSTI2012

Interim Report on the Optimization and Feasibility Studies for the Neutron Detection without Helium-3 Project

This report details the results of the work accomplished for the „Neutron Detection without Helium-3‟ project during the 2011 fiscal year. The primary focus of the project during this year was to develop models using alternatives to helium-3 to investigate the possibilities and optimizations for multiplicity counters in safeguards applications by computer simulations. The multiplicity counter with significant capability, the Epithermal Neutron Multiplicity Counter (ENMC), was used as the baseline requirement for alternative technologies, which, if a suitable alternative can be found, should also satisfy systems with less stringent requirements, including coincidence counters. The project is in collaboration with Los Alamos National Laboratory (LANL), and the baseline model of the ENMC that had been developed at LANL with helium-3 as the detector material was used as a starting point. The model was modified to support optimization investigations, and verified with the helium-3 base material. The model was then modified to incorporate boron-trifluoride (BF3) gas, which can be used as a proportional gas similar to helium-3. The BF3 gas however, cannot be operated at very high pressure, and therefore optimization were performed with lower pressures and involved changing the tube size and number. The simulation of this model is very similar in approach to the model with helium-3 where the simulation ends when the neutron is captured in the boron. The reaction products are easily detected in the proportional gas, and the simulation results of counting the number of reactions matches well with experimental data. Next, the tubes were replaced with boron-lined proportional tubes, where the neutron capture material is a thin boron lining inside the tube wall, and which use standard proportional counting gas. For this alternative, the simulation needs to extend beyond the neutron capture, and track the reaction products, which must exit the boron-lining into the counting gas. The reaction products do not always end up in the counting gas, depending on the boron-lining thickness and neutron capture depth. Methods to track the reaction products have been recently implemented into MCNPX and were verified by using several different approaches. The tube number and size were also varied for the boron-lined case. Finally, work has started on a model of an alternative using lithium-6, another material with a high cross-section for thermal neutron capture. The most promising approach is with lithium fluoride in a zinc sulfide (silver activated) scintillator medium. The neutron is captured in the lithium, and the reaction products trigger scintillation light in the zinc sulfide, which is subsequently detected by photo-multipliers by the use of light guides or fibers. The simulations were performed with the focus on determining the efficiency, which is critical when detecting 2 or 3 neutrons in coincidence, as well as the die-away time, which is a measure of the time required to capture neutrons in the system. The die away time is related to the coincident time gate needed for the system which drives the accidental coincident rate, the primary background or noise in this type of measurement. The usual figure of merit for coincidence type systems, the efficiency squared divided by the die-away time, was calculated for each variation simulated.

helium-3 alternatives↗
DOE OSTI2015

Scintilla European project, the successful research results

The Scintilla FP7 project is ended in December 2014, the fruitful results of 3 years development and tests will be presented. SCINTILLA offers the capacity to finding a reliable alternative to Helium-3 based detection systems since the gas which is predominantly used in nuclear safeguards and security applications has now become very expensive, rare and nearly unavailable. SCINTILLA benchmarks results are based on international standards. Radiation Portal tests were carried out at the Joint Research Centre (JRC) in Ispra (Italy). The scintilla project addresses few mains issues. The first is to develop neutron detectors for Radiation Portal Monitor (RPM) and the second is the need of new wearable integrated solutions for Spectrometric Personal Radiation Monitor (SPRM). The partners which provide technical systems of the scintilla project are INFN-ANSALDO, CEA, SYMETRICA and SAPHYMO. For RPM, the objective is to find reliable alternatives to Helium-3 historical neutron detector and provide technical solutions which cope with tests for reliable mobile and cost effective. For Spectrometric Personal Radiation Monitor (SPRM), SCINTILLA is innovating in technology areas that offer complementary capabilities for detecting and identifying gamma, Two CZT (Cadmium Zinc Telluride) addressing contexts of used by first responder technologies, one is a wearable detector and the second is a gamma camera complemented by advanced image processing technologies. (authors)

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2023

Supplemental Structural Analyses Used in Support of Certification of the Defense Programs Package 3

The Defense Programs Package (DPP)-3 is to be certified by the National Nuclear Security Administration (NNSA) Packaging and Transportation Division (PTD). Certification is based on successful physical testing of the package, and six certification test units (CTUs) have been subjected to the normal conditions of transport (NCT) and hypothetical accident conditions (HAC) outlined in Title 10 of the Code of Federal Regulations Part 71 (10 CFR 71). During regulatory testing of one of the CTUs, the drum lid closure bolt closest to the impact surface failed during the HAC 30-ft side drop. One of the testing goals for this CTU was to minimize the thermal pathway from the drum exterior shell to the containment vessel (CV) flange and O-rings, leading to the maximum damage scenario in preparation for thermal testing at 1475 °F. Therefore, the puncture bar impact proceeded as originally planned by striking the side wall of the package exterior closest to the location of the CV flange. This puncture bar impact did not attempt to exploit the region of the failed drum lid closure bolt to potentially cause more damage to the package. After the conclusion of regulatory testing, the DPP-3 package finite element model was used to numerically evaluate the effects of puncture bar impacts to the drum exterior in the vicinity of the failed drum lid closure bolt to further demonstrate the robustness of the DPP-3 design. Three alternate puncture bar impact locations and orientations were evaluated to demonstrate that these puncture bar impacts would not substantially reduce the effectiveness of the DPP-3 packaging. This paper describes the supplemental finite element models performed and structural analysis results that demonstrate the alternate HAC 40-in. puncture bar impact tests would have no deleterious effect on the performance of the DPP-3.

Sakalaukus Jr., Peter J.↗
DOE OSTI2019

Structural Differences between Pri-miRNA Paralogs Promote Alternative Drosha Cleavage and Expand Target Repertoires

MicroRNA (miRNA) processing begins with Drosha cleavage, the fidelity of which is critical for downstream processing and mature miRNA target specificity. To understand how pri-miRNA sequence and structure influence Drosha cleavage, we studied the maturation of three pri-miR-9 paralogs, which encode the same mature miRNA but differ in the surrounding scaffold. Here, we show that pri-miR-9-1 has a unique Drosha cleavage profile due to its distorted and flexible stem structure. Cleavage of pri-miR-9-1, but not pri-miR-9-2 or pri-miR-9-3, generates an alternative miR-9 with a shifted seed sequence that expands the scope of its target RNAs. Analyses of low-grade glioma patient samples indicate that the alternative-miR-9 has a potential role in tumor progression. Furthermore, we provide evidence that distortion of pri-miRNA stems induced by asymmetric internal loops correlates with Drosha cleavage at non-canonical sites. Our studies reveal that pri-miRNA paralogs can have distinct functions via differential Drosha processing.

59 BASIC BIOLOGICAL SCIENCES↗