Estimating Parametric, Model Form, and Solution Contributions Using Integral Validation Uncertainty Quantification

One of the final steps in building a numerical model of a physical, mechanical, thermal, or chemical process, is to assess its accuracy as well as its sensitivity to input parameters and modeling technique. In this work, we demonstrate one simple process to take a top-down or integral view of the model, one which can implicitly reflect any couplings between parameters, to assess the importance of each aspect of modeling technique. We illustrate with an example of a comparison of a finite element model with data for violent reaction of explosives in accident scenarios. We show the relative importance of each of the main parametric inputs, and the contributions of model form and grid convergence. These can be directly related to the importance factors for the system being analyzed as a whole, and help determine which factors need more attention in future analyses and tests

LX-04 VIOLENCE MEASUREMENTS- STEVEN TESTS IMPACTED BY PROJECTILES SHOT FROM A HOWITZER GUN

Characterization of the reaction violence of LX-04 explosive (85% HMX and 15% Viton A by weight) was obtained from Steven Impact Tests performed above the reaction initiation threshold. A 155 mm Howitzer propellant driven gas gun was used to accelerate the Steven Test projectiles in the range of approximately 170-300 m/s to react (ignite) the LX-04 explosive. Blast overpressure gauges, acoustic microphones, and high-speed photography characterized the level of high explosive reaction violence. A detonation in this velocity range was not observed and when comparing these results (and the Susan test results) with that of other HMX based explosives, LX-04 has a more gradual reaction violence slope as the impact velocity increases. The high binder content (15%) of the LX-04 explosive is believed to be the key factor to the lower level of violence

SHOCK INITIATION EXPERIMENTS ON THE HMX BASED EXPLOSIVE LX-10 WITH ASSOCIATED IGNITION AND GROWTH MODELING

Shock initiation experiments on the HMX based explosives LX-10 (95% HMX, 5% Viton by weight) and LX-07 (90% HMX, 10% Viton by weight) were performed to obtain in-situ pressure gauge data, run-distance-to-detonation thresholds, and Ignition and Growth modeling parameters. A 101 mm diameter propellant driven gas gun was utilized to initiate the explosive samples with manganin piezoresistive pressure gauge packages placed between sample slices. The run-distance-to-detonation points on the Pop-plot for these experiments and prior experiments on another HMX based explosive LX LX-04 (85% HMX, 15% Viton by weight) will be shown, discussed, and compared as a function of the binder content. This parameter set will provide additional information to ensure accurate code predictions for safety scenarios involving HMX explosives with different percent binder content additions

LOW AMPLITUDE SINGLE AND MULTIPLE SHOCK INITIATION EXPERIMENTS AND MODELING OF LX-04

Shock initiation experiments were performed on the plastic bonded explosive (PBX) LX-04 (85% HMX, 15% Viton binder) using single and multiple low amplitude shocks to obtain pressure history data for use in Ignition and Growth reactive flow modeling parameterization. A 100 mm diameter propellant driven gas gun was utilized to initiate the LX-04 explosive charges containing manganin piezoresistive pressure gauge packages placed between explosive discs. In the single shock experiments, the run distances to detonation at three shock pressures showed agreement with previously published data above 3 GPa. Even longer run distances to detonation were measured using 80 mm long by 145 mm diameter LX-04 charges impacted by low velocity projectiles from a 155 mm diameter gun. The minimum shock pressure required to cause low levels of exothermic reaction were determined for these large LX-04 charge dimensions. Multiple shocks were generated as double shocks by using a flyer plate with two materials and as reflected shocks by placing a high impedance material at the rear of the explosive charge. In both cases, the first shock pressure was not high enough to cause detonation of LX-04, and the second shock pressure, which would have been sufficient to cause detonation if generated by a single shock, failed to cause detonation. Thus LX-04 exhibited shock desensitization over a range of 0.6 to 1.4 GPa. The higher shock pressure LX-04 model was extended to accurately simulate these lower pressure and multiple shock gauge records. The shock desensitization effects observed with multiple shock compressions were partially accounted for in the model by using a critical compression corresponding to a shock pressure of 1.2 GPa. This shock desensitization effect occurs at higher pressures than those of other HMX-based PBX's containing higher HMX percentages

SHOCK INITIATION EXPERIMENTS ON PBX 9501 EXPLOSIVE AT PRESSURES BELOW 3 GPa WITH ASSOCIATED IGNITION AND GROWTH MODELING

Shock initiation experiments on the explosive PBX 9501 (95% HMX, 2.5% estane, and 2.5% nitroplasticizer by weight) were performed at pressures below 3 GPa to obtain in-situ pressure gauge data, run-distance-to-detonation thresholds, and Ignition and Growth modeling parameters. Propellant driven gas guns (101 mm and 155 mm) were utilized to initiate the PBX 9501 explosive with manganin piezoresistive pressure gauge packages placed between sample slices. The run-distance-to-detonation points on the Pop-plot for these experiments showed agreement with previously published data and Ignition and Growth modeling parameters were obtained with a good fit to the experimental data. This parameter set will allow accurate code predictions to be calculated for safety scenarios in the low-pressure regime (below 3 GPa) involving PBX 9501 explosive

Nuclear fuels technologies Fiscal Year 1996 research and development test results

During fiscal year 1996, the Department of Energy`s Office of Fissile Materials Disposition (OFMD) funded Los Alamos National Laboratory (LANL) to investigate issues associated with the fabrication of plutonium from dismantled weapons into mixed-oxide (MOX) nuclear fuel for disposition in nuclear power reactors. These issues can be divided into two main categories: issues associated with the fact that the plutonium from dismantled weapons contains gallium, and issues associated with the unique characteristics of the PuO[sub 2] produced by the dry conversion process that OFMD is proposing to convert the weapons material. Initial descriptions of the experimental work performed in fiscal year 1996 to address these issues can be found in Nuclear Fuels Technologies Fiscal Year 1996 Research and Development Test Matrices. However, in some instances the change in programmatic emphasis towards the Parallex program either altered the manner in which some of these experiments were performed (i.e., the work was done as part of the Parallex fabrication development and not as individual separate-effects tests as originally envisioned) or delayed the experiments into Fiscal Year 1997. This report reviews the experiments that were conducted and presents the results

RE: pedagogy – after neutrality

Within the UK and in many parts of the world, official accounts of what it is to make sense of religion are framed within a rhetorics of neutrality in which such study is premised upon the possibility of dispassionate engagement and analysis. This paper, which is largely theoretical in scope, explores both the affordances and the costs of such an approach which has become ‘black boxed’ on account of the work that it achieves. A series of new orientations within the academy that are broadly associated with post-structuralist philosophies, feminist and post-colonial studies, together with insights from Science and Technology Studies, question the plausibility of these claims for neutrality whilst in turn raising a series of new questions and priorities. It therefore becomes necessary to re-think and re-frame what it is to make sense of religious and cultural difference after neutrality. The gathering and co-ordination of new planes of sense-making that are responsive to an emergent series of epistemological, ontological, and ethical orientations are considered. Some of the distinctive pedagogical implications of such an approach that engages material practice, difference and uncertainty are then entertained

Negotiating sacred roles:a sociological exploration of priests who are mothers

In 1992, in a historic move, the Church of England voted to allow women's ordination to priesthood and in 1994 the first women priests started to be ordained. Despite much research interest, the experiences of priests who are mothers to dependent children have been minimally investigated. Based on in-depth interviews with seventeen mothers ordained in the Church, this paper will focus on how the sacred-profane boundary is managed. Priests who are mothers have a particular insight into the Church hierarchy as they symbolically straddle the competing discourses of sacred and profane. However, instead of reifying these binaries, the experiences of these women show how such dualisms are challenged and managed in everyday life. Indeed, in terms of experience, ritual, ministry and preaching, priests who are mothers are resisting, recasting and renegotiating sacred terrain in subtle and nuanced ways. Mothers thus not only negotiate the practical and sacramental demands placed on priests, but also illuminate how the sacred domain is regulated and constructed