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A unique vessel system is being developed to facilitate proton imaging of small-scale shock physics experiments at Los Alamos National Laboratory (LANL). The main components of the system are the Inner Pressure Confinement Vessel (IPCV, which hosts the physics experiment), the Outer Pressure Containment Vessel (OPCV) and Beam Pipes and Auxiliary Hardware (BPAH). The IPCV is an explosively loaded high-pressure vessel which is mounted inside the statically loaded OPCV. The OPCV is attached to a proton beamline. The OPCV and beam pipes form a containment pressure barrier. The detonation of high explosive (HE) inside the IPCV drives material to extreme loading conditions, which are imaged using a proton beam and an imaging system. The IPCV needs to satisfy the ASME Boiler and Pressure Vessel Code, Section VIII, Division 3, Code Case 2564, while allowing for maximum resolution of proton radiography across a sufficiently large field of view. The main components of the IPCV are the vessel body, top and bottom covers, side covers, and radiographic window assemblies. The covers have different feedthroughs mounted on them, such as feedthrough devices for sending or receiving electrical and optical signals across the pressure boundary. The covers also have gas lines with valves for venting the vessel volume. The sealing strategy incorporates a tortuous path and a minimum of 3 O-rings at each vessel cover. The O-ring grooves are designed and tested to seal the vessel before and after the explosive experiment, and to minimize the burp (limited release) during the explosion. While the IPCV is designed for a relatively small HE amount of 30 g TNT equivalent, the radiographic window is located only a few cm away from the HE, which is unique to this specialized high-pressure vessel. To achieve the optimal imaging resolution across the required field of view of 2cm by 2cm, the radiographic windows need to be very thin, located extremely close to the HE, and made of low-attenuating material such as Beryllium. This paper provides an overview of the baseline design, analysis, and testing of the IPCV and its subassemblies.

The results of development testing of the Inner Pressure Confinement Vessel (IPCV) are presented here. The IPCV is part of a two-vessel confinement and containment system designed to support proton radiography of shock physics experiments at Los Alamos National Laboratory (LANL). The IPCV is explosively loaded and designed to confine the high-pressure detonation products, material fragments and any other hazardous materials created by explosively driving materials to extreme loading conditions. The IPCV is designed to meet the requirements of ASME Boiler and Pressure Vessel Code Section VIII, Division 3, Code case 2564. The unique and challenging design consideration for the IPCV is the proximity of the High Explosive (HE) charge to the radiographic imaging windows. The radiographic windows are fabricated from low-attenuating Beryllium which aids in obtaining high resolution radiographic images but is also brittle and susceptible to damage. Several rounds of developmental tests were conducted over the course of a few years. The IPCV is designed to withstand a maximum HE charge size of 30g TNT equivalent. The main components of the IPCV are the Experimental Physics Package (EPP), fragment mitigation assembly, radiographic windows, and gas handling equipment. The radiographic windows are located only a few cm away from the EPP (which houses the HE) and are protected by the fragment mitigation assembly. The gas handling equipment allows for post-shot pressure monitoring and eventual venting of the vessel. The development tests were used to advise the design of the fragment mitigation strategy, develop testing processes and procedures, and collect data for comparison with the engineering models.

Los Alamos National Laboratory (LANL) designs and utilizes impulsively loaded pressure vessels for the confinement of experimental configurations involving explosives. For physics experiments with hazardous materials, a two-barrier containment system is needed, where an impulsively (or, explosively) loaded pressure vessel is assembled as an inner confinement vessel, inside an outer containment vessel (subject to quasi-static load in the event of confinement vessel breach). Design of the inner and outer vessels and support structure must account for any directional loads imparted by the blast loading on the inner vessel. Typically there is a shock-attenuating assembly between the inner confinement and outer containment pressure barriers, which serves to mitigate any dynamic load transfer from inner to outer vessel. Depending on the shock-attenuating approach, numerical predictions of these reaction loads can come with high levels of uncertainty due to model sensitivities. Present work here focuses on the numerical predictions and measurements of the reaction loads due to detonating 30 g of TNT equivalent in the Inner Pressure Confinement Vessel (IPCV) for proton imaging of small-scale shock physics experiments at LANL. Direct reaction load measurements from IPCV testing is presented alongside numerical predictions. Using the experimental measurements from the firing site, we refine the tools and methodology utilized for reaction load predictions and explore the primary model sensitivities which contribute to uncertainties. The numerical tools, modeling methodology, and primary drivers of model uncertainty identified here will improve the capability to model detonation experiments and enable design load calculations of other impulsively loaded pressure vessels with higher accuracy.

We present the results of explosive testing of an Inner Pressure Confinement Vessel (IPCV). The IPCV is explosively-loaded high-pressure vessel which is a part of the containment system to facilitate proton imaging of small-scale shock physics experiments at Los Alamos National Laboratory (LANL). The detonation of high explosive (HE) drives material to extreme loading conditions, which are imaged using a proton beam and an imaging system. The IPCV needs to satisfy the ASME Boiler and Pressure Vessel Code, Section VIII, Division 3, Code Case 2564, while allowing for maximum resolution of proton radiography. The IPCV contains an Experimental Physics Package (EPP), fragment mitigation assembly, and radiographic windows. To achieve the optimal imaging resolution, the radiographic windows need to be very thin, located extremely close to the HE, and made of low-attenuating material such as Beryllium. While the IPCV is designed to a relatively small HE amount of 30 g TNT equivalent, the radiographic window is located only a few cm away from the HE, which is unique to this specialized high-pressure vessel. Fragment mitigation is critical to protecting radiographic windows from any fragments to allow the IPCV to maintain the pressure boundary before and after the explosive experiment. This shielding contains two layers: Boron carbide (B4C) facing the HE and Dyneema (cross plied composite layers made of ultra-high molecular weight polyethylene) facing the window. The B4C plate serves to break up and dull fragments while Dyneema catches fragments and prevents them from contacting the radiographic windows. Design development of the fragment mitigation assembly and attachment was informed by several series of explosive tests at LANL. The tests also addressed the sealing function of vessel covers, gas lines, and isolation valves before and after an explosive experiment.

A containment and confinement pressure vessel system is under development to expand the capability to perform small explosively driven physics experiments at the Proton Radiography facility at Los Alamos National Laboratory (LANL). Two barriers of this vessel system are the Inner Pressure Confinement Vessel (IPCV) and the Outer Pressure Containment Vessel (OPCV). To achieve high spatial resolution of proton images, radiographic windows (covers) of the Inner Vessel are located extremely close to the experiment containing high explosive (HE). While the Inner Vessel is designed to meet the ASME Boiler and Pressure Vessel Code, Section VIII, Division 3, Code Case 2564 criteria, the small separation between the explosive and the pressure-retaining boundary presents a unique requirement for designing dynamically loaded vessels. We present numerical simulations of HE detonation in the Inner Vessel for several HE configurations. Eularian hydrodynamic code is used to calculate pressure-time history on the inner vessel surface. The pressure-time loading is then imported into a Langrangian structural model, and high-fidelity structural dynamic simulations are performed to obtain stress and strain as functions of time. Simulations are compared against experimental measurements from dynamic testing. Dynamic experiments are conducted in a low-fidelity (LoFi) vessel prototype, to measure the pressure and strain in regions of interest in different vessel locations (body, radiographic windows, covers).

A containment system is being developed to expand the capability of proton radiography of small-scale shock physics experiments at Los Alamos National Laboratory (LANL). The detonation of high explosives (HE) drives materials to extreme loading conditions, which are imaged using a proton beam and an imaging system. A qualified confinement and containment boundary needs to exist between a high-explosive experiment and the environment, and is comprised of the Inner Pressure Confinement Vessel (IPCV) and the Outer Pressure Containment Vessel (OPCV). The Inner Vessel is designed to the criteria of the ASME Boiler and Pressure Vessel Code, Section VIII, Division 3, Code Case 2564. The vessel contains an Experimental Physics Package, fragment mitigation structure, and radiographic windows. The windows need to minimize radiographic blur contribution (thin, radiographically transparent material such as Beryllium) over the field of view for imaging, but also need to maintain the pressure boundary during and after the dynamic event. Further, the vessel covers need to seal before, during, and after the experiment . In addition, the covers have miscellaneous feedthroughs, to enable high-voltage signal (for HE detonator), instrumentation and control signals (e.g. valves, pressure and vacuum gauge, optical fibers). We present the preliminary design, analyses, and testing of the Inner Vessel components.

A unique containment and confinement system is under development to conduct small explosively driven physics experiments containing hazardous materials at the Proton Radiography facility at Los Alamos National Laboratory (LANL). In these experiments, the detonation of high explosives (HE) is used to drive materials to extreme loading conditions, where some of the materials tested can be extremely hazardous (e.g. nuclear materials). The main components of the system are the Inner Pressure Confinement Vessel (IPCV, which hosts the physics experiment), the Outer Pressure Containment Vessel (OPCV) and Beam Pipes and Auxiliary Hardware (BPAH). This paper describes the design and preliminary analyses of the IPCV. The body of the IPCV, also referred to as the Inner Vessel, is being designed to the criteria of the ASME Boiler and Pressure Vessel Code, Section VIII, Division 3, Code Case 2564, with the exception of the materials of construction. The closure covers have different devices mounted on them, such as feedthrough devices for sending or receiving electrical and optical signals across the pressure boundary, and valves for venting the vessel interior. The unique feature in the vessel design are the radiographic windows, tentatively made of Beryllium, which need to be strong enough to maintain the pressure boundary during dynamic events, while being radiographically low-attenuating for the purpose of proton imaging.