Scorpius: The development of a new multi-pulse radiographic system

The second axis (Axis II) of the Dual-Axis Radiographic Hydrodynamic Test (DARHT) facility at Los Alamos National Laboratory (LANL) is a linear induction accelerator (LIA) using 74 cells, each driven by a separate pulsed-power modulator. The summation of the injector and 74 cell voltages is the beam-energy temporal profile. The ability to perform precise multi-pulse radiography is heavily influenced by the temporal beam energy spread, related beam motion, and other focusing and target factors. Beam loading affects both the shape and magnitude of each cell's voltage during the pulse. Ideally, each pulsed-power modulator/cell pair is tuned such that the loaded-cell voltage is flat with minimal amplitude variation during the pulse. However, changes in operating parameters on Axis II (beam current, operating cell voltage) have altered the amount of flattop variation resulting in more energy spread than when commissioned. In this paper, we present an optimization and synthesis method which minimizes the beam's temporal energy spread by adjusting the timing of cell voltages, either advancing or retarding them, such that the injector voltage plus the summed cell voltages in the LIA result in a flatter energy profile. The method accepts as inputs the beam current, injector voltage, cell-voltages, and synthesizes loaded cell voltages as needed. Simulations and experimental data for both unloaded and loaded-cell timing optimizations are presented. For the unloaded cells, the pre-optimization baseline energy spread was reduced by over 30 % as compared to baseline. For the loaded-cell case, the measured energy spread was reduced by 49% compared to baseline.

This report documents the review of Application for Contents Amendment for Shipping Isentropic Compression Experiment (ICE) Apparatus in 9977 Packaging, prepared by Savannah River Packaging Technology (SRPT) of Savannah River National Laboratory (SRNL) of Savannah River Nuclear Solutions, LLC, -- the Submittal -- at the request of the Department of Energy's (DOE) National Nuclear Security Agency's (NNSA) Albuquerque Facility Operations Division, for the shipment of the ICE apparatus from Los Alamos National Laboratory (LANL), to Sandia National Laboratory (SNL). The ICE apparatus consists of a stainless steel assembly containing about 8 grams of {sup 239}Pu or its dose equivalent as noted in Table 1, Comparison of 9977 Content C.1 and the ICE Radioactive Contents, of the Submittal. The ICE target is mounted on the transport container assembly base. A Viton{sup R} O-ring seals the transport container base to the transport container body. Another Viton{sup R} O-ring seals the transport container handle to the transport container body. The ICE apparatus weighs less than 30 pounds and has less than 0.6 watts decay heat rate. For the Model 9977 Package, the maximum payload weight is 100 pounds and the maximum decay heat rate is 19 watts. Thus, the maximum payload weight and the maximum decay heat rate for the Model 9977 Package easily bound those for the ICE apparatus. This Addendum supplements the Safety Analysis Report for Packaging (SARP), Revision 2, for the Model 9977 Package and Addendum 1, Revision 2, to Revision 2 of the Model 9977 Package SARP. The ICE apparatus is considered as part of Content Envelope C.6, Samples and Sources, under the submittal for the Model 9978 Package SARP currently under review. The Staff at Lawrence Livermore National Laboratory (LLNL) recommends that the Submittal be approved by the DOE-Headquarters Certifying Official (EM-60), and incorporated into a subsequent revision to the current Certificate of Compliance (CoC), to the Model 9977-96 Packaging.

This document was prepared to support u.s. Department of Energy / National Nuclear Security Agency (DOE/NNSA) compliance with Sections 106 and 110 of the National Historic Preservation Act (NHPA). Lawrence Livermore National Laboratory (LLNL) is a DOE/NNSA laboratory and is engaged in determining the historic status of its properties at both its main site in Livermore, California, and Site 300, its test site located eleven miles from the main site. LLNL contracted with the authors via Sandia National Laboratories (SNL) to prepare a historic context statement for properties at both sites and to provide assessments of those properties of potential historic interest. The report contains an extensive historic context statement and the assessments of individual properties and groups of properties determined, via criteria established in the context statement, to be of potential interest. The historic context statement addresses the four contexts within which LLNL falls: Local History, World War II History (WWII), Cold War History, and Post-Cold War History. Appropriate historic preservation themes relevant to LLNL's history are delineated within each context. In addition, thresholds are identified for historic significance within each of the contexts based on the explication and understanding of the Secretary of the Interior's Guidelines for determining eligibility for the National Register of Historic Places. The report identifies specific research areas and events in LLNL's history that are of interest and the portions of the built environment in which they occurred. Based on that discussion, properties of potential interest are identified and assessments of them are provided. Twenty individual buildings and three areas of potential historic interest were assessed. The final recommendation is that, of these, LLNL has five individual historic buildings, two sets of historic objects, and two historic districts eligible for the National Register. All are eligible within the Cold War History context. They are listed in the table below, along with the Cold War preservation theme, period of significance, and criterion under which they are eligible.

Flash radiography of hydrodynamic experiments driven by high explosives is a well-known diagnostic technique in use at many laboratories. At Los Alamos, the Dual Axis Radiographic Hydrodynamic Test (DARHT) facility two linear induction electron accelerators (LIAs) make the bremsstrahlung radiographic source spots for point projection radiographs from orthogonal views. A new LIA, called Scorpius, is presently under development to advance this technology. To better understand electron-beam physics in these LIAs, numerical simulations are frequently performed with the objective of improving the radiography. At Los Alamos we frequently use the TRAK ray-trace and LSP particle-in-cell (PIC) codes to simulate the injector, and the XTR and LAMDA envelope/centroid codes along with LSP to simulate transport of the accelerated beam through the LIAs. The LIA simulations need the injected beam parameters as initial conditions for calculating beam transport and stability. The determination of these initial conditions is the topic of this note.

This report highlights the results of FY 2000 technical studies conducted by the Analytical and Nuclear Chemistry Division (ANCD) at Lawrence Livermore National Laboratory (LLNL) in support of the Hydrology and Radionuclide Migration Program (HRMP) and Underground Test Area (UGTA) Project. This is the latest in a series of annual reports published by LLNL-ANCD to document recent investigations of radionuclide migration and transport processes at the Nevada Test Site (NTS). The HRMP is sponsored by Defense Programs (DP) at the U.S. Department of Energy, Nevada Operations Office (DOENV), and supports DP operations at the NTS through studies of radiochemical and hydrologic processes that are relevant to the DP mission. Other organizations that support the HRMP include Los Alamos National Laboratory (LANL), the U.S. Geological Survey (USGS), the Desert Research Institute (DRI) of the University of Nevada, the U.S. Environmental Protection Agency (EPS), and Bechtel Nevada (BN). The UGTA Project is sponsored by the Environmental Management (EM) program at DOENV; its goal is to determine the extent of radionuclide contamination in groundwater resulting from underground nuclear testing at the NTS. The project strategy follows guidelines set forth in a Federal Facilities Agreement and Consent Order between the U.S. Department of Energy, the U.S. Department of Defense, and the State of Nevada. Participating contractors include LLNL (both ANCD and the Energy and Environmental Sciences Directorate), LANL, USGS, DRI, BN, and IT Corporation (with subcontract support from Geotrans Inc.).

The Record of Decision on the Dual Axis Radiographic Hydrodynamic Test Facility at the Los Alamos National Laboratory requires that the Department of Energy takes special precautions to protect the Mexican Spotted Owl (Strix occidentalis lucida). In order to do so, risk to the owl presented by radiological and nonradiological contaminants must be estimated. A preliminary risk assessment on the Mexican Spotted Owl in two Ecological Exposure Units (EEUs) was performed using a modified Environmental Protection Agency Quotient method, the FORTRAN model ECORSK4, and a geographic information system. Estimated doses to the owl under a spatially-weighted foraging regime were compared against toxicological reference doses generating hazard indices (HIs) and hazard quotients (HQs) for three risk source types. The average HI was 0.20 for EEU-21 and 0.0015 for EEU-40. Under the risk parameter assumptions made, hazard quotient results indicated no unacceptable risk to the owl, including a measure of cumulative effects from multiple contaminants that assumes a linear additive toxicity type. An HI of 1.0 was used as the evaluative criteria for determining the acceptability of risk. This value was exceeded (1.06) in only one of 200 simulated potential nest sites. Cesium-137, Ni, {sup 239}Pu, Al and {sup 234}U we`re among the constituents with the highest partial HQs. Improving model realism by weighting simulated owl foraging based on distance from potential nest sites decreased the estimated risk by 72% (0.5 HI units) for EEU-21 and by 97.6% (6.3E-02 HI units) for EEU-40. Information on risk by specific geographical location was generated, which can be used to manage contaminated areas, owl habitat, facility siting, and/or facility operations in order to maintain risk from contaminants at acceptably low levels.

Test H3837 was the first explosive shot performed in front of both flash x-ray axes at the Los Alamos Dual Axis Radiographic Hydrodynamic Test (DARHT) facility. Executed in November 2009, the shot was an explosively-driven metal flyer plate in a series of experiments designed to explore equation-of-state properties of shocked materials. Imaging the initial shock wave traveling through the flyer plate, DARHT Axis II captured the range of motion from the shock front emergence in the flyer to breakout at the free surface; the Axis I pulse provided a perpendicular perspective of the shot at a time coinciding with the third pulse of Axis II.

On May 12, 1995, the U.S. Department of Energy (DOE) issued the draft Dual Axis Radiographic Hydrodynamic Test Facility Environmental Impact Statement (DARHT EIS) for review by the State of New Mexico, Indian Tribes, local governments, other Federal agencies, and the general public. DOE invited comments on the accuracy and adequacy of the draft EIS and any other matters pertaining to their environmental reviews. The formal comment period ran for 45 days, to June 26, 1995, although DOE indicated that late comments would be considered to the extent possible. As part of the public comment process, DOE held two public hearings in Los Alamos and Santa Fe, New Mexico, on May 31 and June 1, 1995. In addition, DOE made the draft classified supplement to the DARHT EIS available for review by appropriately cleared individuals with a need to know the classified information. Reviewers of the classified material included the State of New Mexico, the U.S. Environmental Protection Agency, the Department of Defense, and certain Indian Tribes. Volume 2 of the final DARHT EIS contains three chapters. Chapter 1 includes a collective summary of the comments received and DOE`s response. Chapter 2 contains the full text of the public comments on the draft DARHT EIS received by DOE. Chapter 3 contains DOE`s responses to the public comments and an indication as to how the comments were considered in the final EIS.

This paper describes the mechanical design of the downstream beam transport line for the second axis of the Dual Axis Radiographic Hydrodynamic Test (DARHT II) Facility. The DARHT II project is a collaboration between LANL, LBNL and LLNL. DARHT II is a 20-MeV, 2000-Amperes, 2-/spl mu/sec linear induction accelerator designed to generate short bursts of X-rays for the purpose of radiographing dense objects. The downstream beam transport line is an 18-meter long region extending from the end of the accelerator to the bremsstrahlung target. Within this proposed transport line there are 17 conventional solenoid, quadrupole and dipole magnets; as well as several specialty magnets, which transport and focus the beam to the target and beam dumps. There is a high power beam dump, which is designed to absorb 80-kJ per pulse during accelerator start-up and operation. The beamline vacuum chamber has an 8-cm diameter aperture and operates at an average pressure of 10/sup -7/ Torr.

Lawrence Livermore National Laboratory (LLNL) Containment Program performed a review of nuclear test-related data for the Norbo underground nuclear test in U8c to assist in evaluating this legacy site as a test bed for application technologies for use in On-Site Inspections (OSI) under the Comprehensive Nuclear Test Ban Treaty. This request is similar to one made for the Salut site in U8c (Pawloski, 2012b). Review of the Norbo site is complicated because the test first exhibited subsurface collapse, which was not unusual, but it then collapsed to the surface over one year later, which was unusual. Of particular interest is the stability of the ground surface above the Norbo detonation point. Proposed methods for on-site verification include radiological signatures, artifacts from nuclear testing activities, and imaging to identify alteration to the subsurface hydrogeology due to the nuclear detonation. Aviva Sussman from the Los Alamos National Laboratory (LANL) has also proposed work at this site. Both proposals require physical access at or near the ground surface of specific underground nuclear test locations at the Nevada Nuclear Security Site (NNSS), formerly the Nevada Test Site (NTS), and focus on possible activities such as visual observation, multispectral measurements, and shallow and deep geophysical surveys.

We are constructing a 1.2 kA, 1 MeV, electron induction injector as part of the RTA program, a collaborative effort between LLNL and LBNL to develop relativistic klystrons for Two-Beam Accelerator applications. The RTA injector will also be used in the development of a high-gradient, low-emittance, electron source and beam diagnostics for the second axis of the Dual Axis Radiographic Hydrodynamic Test (DARHT) Facility. The electron source will be a 3.5″-diameter, thermionic, flat-surface, m-type cathode with a maximum shroud field stress of approximately 165 kV/cm. Additional design parameters for the injector include a pulse length of over 150 ns flat top (1% energy variation), and a normalized edge emittance of less than 200 π-mm-mr. Precise measurement of the beam parameters is required so that performance of the RTA injector can be confidently scaled to the 4 kA, 3 MeV, and 2-microsecond pulse parameters of the DARHT injector. Planned diagnostics include an isolated cathode with resistive divider for direct measurement of current emission, resistive wall and magnetic probe current monitors for measuring beam current and centroid position, capacitive probes for measuring A-K gap voltage, an energy spectrometer, and a pepperpot emittance diagnostic. Details of the injector, beam line, and diagnostics are presented.

The potential for the contamination of ground water beneath the Nevada Test Site (NTS) by nuclear testing has long been recognized. The United States has conducted underground nuclear weapons testing at NTS since 1957, and a considerable amount of radioactive material has been deposited in the subsurface by this work. As a part of the U.S. Department of Energy Nevada Operations Office’s Underground Test Area Operable Unit (UGTA OP), the Lawrence Livermore National Laboratory (LLNL) has compiled an inventory of radionuclides produced by underground LLNL weapons tests from 1957 through 1992.

The object of inertial confinement fusion (ICF) is to compress a fuel capsule to a state with high enough density and temperature to ignite, starting a self-sustaining fusion burn that consumes much of the fuel and releases a large amount of energy. The national ICF research program is trying to reach this goal, especially through experiments at the OMEGA laser facility of the University of Rochester Laboratory of Laser Energetics (LLE), planned experiments at the National Ignition Facility (NIF) under construction at the Lawrence Livermore National Laboratory (LLNL), and experimental and theoretical work at other national laboratories. The work by MIT reported here has played several important roles in this national program. First, the development of new and improved charged-particle-based plasma diagnostics has allowed the gathering of new and unique diagnostic information about the implosions of fuel capsules in ICF experiments, providing new means for evaluating experiments and for studying capsule implosion dynamics. Proton spectrometers have become the standard for evaluating the mass assembly in compressed capsules in experiments at OMEGA; the measured energy downshift of either primary or secondary D3He fusion protons to determines the areal density, or ?R, of imploded capsules. The Proton Temporal Diagnostic measures the time history of fusion burn, and multiple proton emission imaging cameras reveal the 3-D spatial distribution of fusion burn. A new compact neutron spectrometer, for measuring fusion yield, is described here for the first time. And of especially high importance to future work is the Magnetic Recoil Spectrometer (MRS), which is a neutron spectrometer that will be used to study a range of important performance parameters in future experiments at the NIF. A prototype is currently being prepared for testing at OMEGA, using a magnet funded by this grant. Second, MIT has used these diagnostic instruments to perform its own physics experiments and analysis with implosions at OMEGA, to provide essential data to other experimenters at LLE, and to work collaboratively with researchers from all the national laboratories (including LLNL, Los Alamos National Laboratory, and Sandia National Laboratory). Some of the implosion dynamics physics studies reported here involve the relationships between drive asymmetries and implosion asymmetries (in terms of both mass assembly and fusion burn); the time evolution of mass assembly and mass asymmetries; the behavior of shock coalescence; and the nature of fuel-shell mix. Third, the MIT program has provided unique educational and research opportunities for both graduate and undergraduate students. The graduate students are deeply engaged in every aspect of our research program, and spend considerable time at OMEGA working on experiments and working with our collaborators from OMEGA and from the National Labs. Many undergraduates have gotten a taste of ICF research, sometimes making significant contributions. We believe that the introduction of energetic and gifted students to the challenging problems of this field and the excitement of the national lab environment leads naturally to the infusion of bright, talented young scientists into our field, and several PhD recipients from this group have become important forces in the field. Finally, this work has provided the foundation for continuing advances during upcoming research, with other experimental and theoretical studies of implosion dynamics. In addition to the continuing application of diagnostic instrumentation used during this grant, important contributions will be made with new diagnostics such as the MRS and with new techniques based on the knowledge obtained here, such as proton radiography.

Previous studies Los Alamos National Laboratory (LANL) found elevated ratios of chlorine-36 to total chloride (36Cl/Cl) in samples of rock collected from the Exploratory Studies Facility (ESF) at Yucca Mountain (YM). The data were interpreted as an indication that fluids containing “bomb-pulse” 36Cl reached the repository horizon in the ~50 years since the peak period of above-ground nuclear testing. Due to the significance of 36Cl data to conceptual models of unsaturated zone flow, the United States Geological Survey (USGS) implemented a study to validate the LANL findings. The USGS drilled new boreholes at select locations across zones where bomb-pulse ratios had previously been identified. The drill cores were analyzed at Lawrence Livermore National Laboratory (LLNL). Because consensus was not reached between the USGS/LLNL and LANL on several fundamental points including the presence or absence of bomb-pulse 36Cl, an evaluation by the University of Nevada, Las Vegas (UNLV), was initiated. The overall objectives of the UNLV study were to investigate the source of the validation study’s conflicting results, and to obtain additional data on bomb-pulse isotopes at the repository horizon. UNLV engaged in discussions with previous investigators, reviewed reports, and analyzed archived samples. UNLV also collected new samples of rock from the ESF, soil profiles from the surface of YM, and samples of seep water from inside the ESF. Samples were analyzed for 36Cl/Cl ratios, and 99Tc and 129I in select samples. A column experiment was conducted mimicking the passage of bomb-pulse 36Cl through YM tuff. The work faced several obstacles including an extended shutdown of the tunnel. Only one sample yielded a background corrected 36Cl/Cl ratio that was higher than the accepted bomb-pulse threshold (1250 x 10-15). Specimen 01034214 obtained from the Drill Hole Wash fault (19+33) had a ratio of 1590 ± 80 (1σ) x10-15, whereas the other separate sample from this fault zone yielded 1160 ± 50 (1σ) x 10-15. Three samples collected from Alcove 6 averaged 490 ± 100 (1σ) x10-15; a sample from Sundance Fault resulted in a ratio of 920 ± 60 (1σ) x10-15, and a sample from the Bow Ridge Fault produced 530 ± 20 (1σ) x10-15. The results are significant because: 1) they tend to be lower than LANL data for comparable samples, albeit in agreement with the range of data produced in the area, and 2) they show that a bomb-pulse 36Cl/Cl ratio was measured in rock collected at the repository horizon level by a second and independent group of investigators (UNLV). Because of time UNLV was not able to replicate the results, and these few data points are insufficient to draw major and definitive conclusions. Leachates of soil samples collected from the surface above the ESF yielded several ratios with bomb-pulse 36Cl, particularly for samples encompassing the wetting front. Soil samples collected above the south ramp, where there was limited soil coverage due to a large amount of rock outcrop, had relatively large ratios ranging from 2170 ± 110 (1σ) x10-15 to 5670 ± 350 (1σ) x10-15. Soil samples from profiles from above the north ramp ranged from 820 ± 70 (1σ) x10-15 to 2390 ± 160 (1σ) x10-15, which compare favorably with previous measurements near the site. Water seepage into the ESF south ramp and 36Cl standards made from NIST material were also analyzed. The standards were produced to have nominal 36Cl/Cl ratios (10-15) of 500, 2,500 and 10,000 and the results showed good agreement with the calculated ratios. The seepage samples ranged between 680 ± 40 (1σ) x10-15 to 1110 ± 40 (1σ) x10-15, consistent with that found for modern meteoric water, with a small bomb-pulse component. Bomb-pulse 36Cl may not have been incorporated in this fast-path water because the surface above the infiltration zone consists mostly of outcrop and the flow pathways have probably mostly been leached. 99Tc was measured in five of nine leaches of ESF rock but poor analytical recoveries and lack of data overlap with 36Cl limit interpretations of these data. The detection capability of the ICP-MS was insufficient for measuring 129I without preconcentration, and detection by AMS may be preferable. Experiments were conducted using bromide instead of chloride as a carrier, which is advantageous because it may eliminate the need for blank subtraction. ESF samples prepared using bromide had 36Cl/Cl ratios (x10-15) with acceptable levels of uncertainty (1σ): 720 ± 30 and 1250 ± 90 for Bow Ridge and Drill Hole Wash Faults, respectively. The result for the latter is noteworthy because it constitutes a second detection of a 36Cl/Cl bomb-pulse ratio at the site, albeit from a non-Q measurement. The source of the conflicting results between USGS/LLNL and LANL could not be determined. There was no evidence that the different AMS facilities were a source of the discrepancy between the results.

The Lawrence Livermore National Laboratory (LLNL) is conducting a generic test of retrievable geologic storage of nuclear spent fuel assemlbies, in an underground chamber, at the Nevada Test Site, Nye County, Nevada. This generic test is located 420 m below the surface, in the Climax granitic stock. Eleven canisters of spent fuel approximately 2.5 years out of reactor core (about 1.6 kW/canister thermal output) are now emplaced in a storage drift, along with 6 electrical heaters which simulate fuel canisters. Two adjacent drifts contain other electrical heaters, which will be operated to simulate the thermal field of a large repository. An analysis of the mine-by at SFT-C was performed by means of refined finite element models using the JPLAXD code (Jointed, PLane and AXisymmetric, Dilatant). The input for the new models was derived from our field program, which is reported separately. Stress results obtained by modeling methods are compared. All models show that, during mining of the center drift, all caverns close vertically, and the center drift closes horizontally. The walls of the two heater drifts move toward the center drift, with a slight opening or a slight closing of the heater drifts, depending upon the geology. All calculations show both pillars expanding laterally during mine-by. The field-reported lateral contraction of the pillars leads to the very suspicious conclusion that the pillars end up in a state of tension. The field-reported values from horizontal MPEs and horizontal tapes appear to be inconsistent with each other. (DMC)