Rebecca S. Detwiler

PRex: An Experiment to Investigate Detection of Near-field Particulate Deposition from a Simulated Underground Nuclear Weapons Test Vent.

AbstractA radioactive particulate release experiment to produce a near-field ground deposition representative of small-scale venting from an underground nuclear test was conducted to gather data in support of treaty capability development activities. For this experiment, a CO2‐driven “air cannon” was used to inject 140La, a radioisotope of lanthanum with 1.7‐d half-life and strong gamma-ray emissions, into the lowest levels of the atmosphere at ambient temperatures. Witness plates and air samplers were laid out in an irregular grid covering the area where the plume was anticipated to deposit based on climatological wind records. This experiment was performed at the Nevada National Security Site, where existing infrastructure, radiological procedures, and support personnel facilitated planning and execution of the work. A vehicle-mounted NaI(Tl) spectrometer and a polyvinyl toluene-based backpack instrument were used to survey the deposited plume. Hand-held instruments, including NaI(Tl) and lanthanum bromide scintillators and high purity germanium spectrometers, were used to take in situ measurements. Additionally, three soil sampling techniques were investigated and compared. The relative sensitivity and utility of sampling and survey methods are discussed in the context of on-site inspection.

Applications of nuclear resonance fluorescence

Nuclear Resonance Fluorescence (NRF) has the potential of addressing a wide variety of applications, which require isotopic and/or elemental information about a sample. We have investigated a variety of non-proliferation applications that may be addressed by NRF. From these applications, we have selected two, measuring uranium enrichment in UF6 cylinders and material verification in dismantlement, to investigate in more detail. Analytical models have been developed to evaluate these applications, and test measurements have been conducted to validate those models. We found that it is unlikely with current technology to address the requirements for UF6 cylinder enrichment measurements. In contrast, NRF is a very promising approach for material verification for dismantlement.

Particle Release Experiment (PRex) Final Report

...................................................................................................................................................... iii Executive Summary .................................................................................................................................... v Acknowledgments ..................................................................................................................................... vii Acronyms and Abbreviations ................................................................................................................... ix 1.0 Introduction ............................................................................................................................ 1 1.1 Background .............................................................................................................................. 1 1.2 Objective .................................................................................................................................. 2 1.3 Scope of Document .................................................................................................................. 2 2.0 Experimental Considerations ................................................................................................ 3 2.1 Overview of PRex .................................................................................................................... 3 2.2 Constraints ............................................................................................................................... 3 2.3 Assumptions ............................................................................................................................. 4 2.4 Pre-Execution Release Parameters ........................................................................................... 4 3.0 PRex Experiment Preparation .............................................................................................. 6 3.1 Experiment Plan ....................................................................................................................... 6 3.2 Site Selection............................................................................................................................ 6 3.3 Background Measurements, September and October 2012 ..................................................... 7 3.4 Source Production .................................................................................................................... 9 3.4.1 Preparation of La2O3 Powder .................................................................................................................. 9 3.4.2 Irradiation at Washington State University ........................................................................................... 12 3.4.3 Source Transport ................................................................................................................................... 14 3.5 Release Mechanism ................................................................................................................ 19 3.6 Meteorology Planning and Modeling ..................................................................................... 22 3.7 NNSS Experiment Site Preparation ....................................................................................... 22 3.7.1 Posting Contamination and High Contamination Areas ....................................................................... 22 3.7.2 Prepositioned Sampling ........................................................................................................................ 22 4.0 PRex Experiment Execution ............................................................................................... 28 4.1 Time and Location ................................................................................................................. 28 4.2 Meteorological Conditions during Release ............................................................................ 28 4.3 Sampling Network ................................................................................................................. 32 4.3.1 Collection of Witness Plates ................................................................................................................. 32 4.3.2 Soil Sampling ....................................................................................................................................... 33 4.3.3 Air Sampling ......................................................................................................................................... 36 4.4 Radiation Survey .................................................................................................................... 36 4.4.1 Vehicle Survey...................................................................................................................................... 37 4.4.2 Handheld/Man-portable ........................................................................................................................ 38 4.4.3 Aerial Survey ........................................................................................................................................ 39 4.5 Field Laboratory ..................................................................................................................... 40