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DOE OSTI2016

Software Dependability for Digital Instrumentation and Control Systems in Nuclear Power Plants - Lessons Learnt from a DOE Sponsored Project

This paper discusses the lessons learnt from a sponsored study undertaken under the sponsorship of the Department of Energy by a team of scientists at the Ohio State University in collaboration with Technology Resources and experts around the world. This paper makes recommendations for future research and studies based on these lessons learnt. The purpose of the research was to provide a software dependability quantification framework that would allow its evaluation along the software development life cycle for safety critical instrumentation and control systems (I and C) such as those found in nuclear power plants. A typical example of safety critical system is the reactor protection system. The research funded by the Department of Energy built on preliminary research carried out for the US NRC that had focused solely on software reliability quantification. Quantification of software dependability is important for safety critical I and C because the regulatory framework in use in the United States for nuclear power plants is risk informed. Quantification of risk requires quantification of all contributors to risk and those include instrumentation and control systems. The purpose of the study was to help developers of software-based I and C with an early evaluation of the potential risk an application would represent at different stages of the software development life cycle by building gates at the end of each life cycle phase. Life cycle phases of software development comprehend phases such as requirements, design, coding and test. The gates' function would be to stop development from moving forward if the assessed dependability objective for that phase were not met. Gates thresholds were to be defined based on measurements collected during the life cycle phase under evaluation and phases that preceded it and an understanding of the mechanisms that would lead to threatening the dependability objectives. The information contained in the gates would in addition help steer the development towards areas that needed improvement. The following are four high level conclusions to our study. First the study demonstrates a lack of consensus on mechanisms that will threaten the dependability attributes. This lack of consensus should be resolved. The lack of consensus appears for all measures to the exception of reliability. Second, measures should be developed for software availability and safety. Third, for all dependability attributes (with the exception of reliability) consistency of the measurement threads should evaluated and measurement-based development gates derived. Finally our ability to perform such type of research depends in a significant manner on access to vendor and/or utility data. The licensing environment and the first-of-a-kind nature of current software-based applications for nuclear I and C make it difficult to collect the relevant data. An approach which would either increase access to data by providing 'immunity' to the vendor or utility or the development of a software-based I and C for the sole purpose of data collection for research should be investigated. (authors)

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

DOE OSTI2019

Refocusing an Employee Engagement Organization to Improve Participation, Member Benefits, and Impact - 19036

Washington River Protection Solutions, LLC (WRPS) provides its employees with programs and opportunities to develop professional skills and to network. Among these is an employee engagement organization called 'WRPSpeed'. WRPSpeed was founded in 2009 initially to support new employees, specifically early-career employees and those new to the Columbia Basin area surrounding the Hanford Site. It was, and remains today, an opt-in program, meaning that in order to join, employees must request to become a member; the only requirement to join is to be a WRPS employee. WRPSpeed has historically offered presentations on professional development topics along with various events and activities supporting professional networking, such as after-work-hours events and community sports teams. Since its creation, WRPSpeed has experienced an ebb and flow of interest, participation, and success. Beginning in early 2017, existing members of the WRPSpeed board examined the stagnant growth trend of the organization and determined change was needed in order to truly accomplish the mission and goals visualized by the board and by WRPS management. These changes culminated in the establishment of a new board position, Marketing and Branding, which allowed WRPSpeed to refocus their messaging and image expressed to the WRPS employee base at large. The primary objectives of the new Marketing and Branding board position were 1) to communicate the identity of WRPSpeed, 2) to communicate the benefits of participation to the WRPS employee base, and 3) to grow WRPSpeed's presence as an active community steward. During the previous years of operation, its brand had developed two main audience perception problems: a perception of exclusivity, which limited membership growth; and a lack of recognition and awareness. Though initially founded as a group for new and early-career employees, the board recognized the benefits of offering all employees the opportunity to participate. This allows more people to engage in the organization and experience the benefits, and also offers the membership and program a more robust network of professional and personal experiences and connections. Concurrent with the launch of Marketing and Branding, the WRPSpeed board reviewed their current functions and activities to determine opportunities for improvement and scale-up. The goal of this internal review was to ensure the benefits offered and advertised by WRPSpeed were high quality, valuable, and engaging. It was up to Marketing and Branding to develop strategies for the success of these efforts and reach all parties in the expanded membership. A marketing communications strategy was developed to establish a revitalized WRPSpeed image and clearly project that new image to a wider audience. The first step was to rewrite the mission statement for the organization, which established, in writing, its primary pillars: community stewardship, professional networking, and professional development. With a new mission statement and the WRPSpeed board in concurrence with - and coached on - the new image, the Marketing and Branding team launched its rebranding campaign. The campaign included a refreshed logo and theme, a new monthly newsletter for existing membership, increased and consistently stylized communications about events, a revitalized organization web page, and a ramp-up schedule for large-scale, multimedia communications to the entire company. From July 2017, when they began, to June 2018, the Marketing and Branding efforts have garnered a 20% increase in membership overall. Additionally, members surveyed in May 2018 showed 49% of respondents had been participating in WRPSpeed between 0 and 12 months; 13% responded '1-2 years'; and 38% responded '2+ years'. These results confirm an upward trend in membership, and attendance records show an increase in new people attending events. Also, parallel increases in number and quality of activities and increases in networking with employee groups from other local companies such as Bechtel National, Inc. and AECOM have improved member satisfaction and positive word of mouth among the employee population. As with any organization, employee engagement-and-retention groups like WRPSpeed face the challenges of staying relevant and beneficial to existing members while continuing to grow their program and impact. However, employee engagement organizations also have the unique opportunity to connect employees across the company and to provide them opportunities otherwise unavailable via other programs. Often these groups also have the flexibility to tailor the offerings, events, and activities to suit the specific needs and aspirations of the employees. With this exceptional position, it is important to continue to strive to offer high quality, significant, and useful benefits to the employees and, thus, the company. The strategies and campaigns employed to revitalize WRPSpeed have proven exceptionally effective in-house and are useful to other employee groups as templates for their own improvement and as opportunities for benchmarking. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2020

Metal Bioavailability and Ecotoxicity of Bioremediated Oils and Tailings by BioTiger{sup TM}, a Microbial Consortium

Oil Sands and Mature Fine Tailings: Oil sand reserves are a major source of oil for the United States. Oil sands are a mixture of sand, clay, water, and bitumen. The refining process requires large volumes of water and generates hazardous Mature Fine Tailings (MFTs) that are stored in engineered settling ponds. They are of major environmental concern due to their persistence and difficulty to naturally biodegrade. MFT Contaminants of Concern: Naphthenic Acids (NAs), Polycyclic Aromatic Hydrocarbons (PAHs), Benzene, Toluene, Ethylbenzene and Xylene (BTEX), Metals, Residual Bitumen. BioTiger{sup TM} (BT{sup TM}), the SRNL patented 12 component microbial consortia was found to cometabolically degrade some NAs and PAHs. Previous studies performing short term exposure (48 hours and 7 days) to BT{sup TM} have resulted in increased toxicity due to the partial degradation of PAHs forming toxic intermediates. Objective: Evaluate the ecotoxicity of BT{sup TM} remediated MFTs exposed to a 2 week period w/ yeast (Y) extract. This work will determine BT{sup TM}'s remediation of MFTs from Fort McMurray, Alberta. Acute toxicity tests will be performed under section 9 of EPA's Method for Measuring Acute Toxicity using the freshwater organism, Ceriodaphnia dubia. Monitor BT{sup TM} growth through Most Probable Number (MPN) counts, pH, and metal bioavailability will also be evaluated. Preparing tailing solutions for biodegradation: BT{sup TM} components were grown in R2A media and combined. Mother BT{sup TM} was centrifuged at 7000 rpm for 20 minutes and resuspended in Bushnell Haus. 33 g of tailings were added to 1100 mL Bushnell Haus along with yeast extract (11 g) to create a 3% tailing solution. Treatments were performed in triplicate. Preparing solutions for toxicity tests using C. dubia: Supernatant was collected immediately after centrifuging at 7000 rpm for 20 min. Supernatant was filtered via a 0.22 μm sterile system. All treatments except MFT, Y peaked at T=4. This decrease in microbial growth could be associated with toxicity from intermediate byproducts. Treatments containing only MFTs decreased in the initial 11 days before growing significantly. Final solution for MFT, Y treatment had the highest pH. This could potentially be due to increased microbial activity linked with yeast consumption. All treatments except MFT, Y peaked at T=4. This decrease in microbial growth could be associated with toxicity from intermediate byproducts. Treatments containing only MFTs decreased in the initial 11 days before growing significantly. Future Direction: Await results from Acute Toxicity Tests and Metal Bioavailability Quantification of biosurfactant production. Evaluate hydrocarbon degradation byproducts using an analytical chemistry approach. More toxicity experiments with variations in time and conditions.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2020

Analysis of Material Properties of Aged Rigid Polyurethane Foam

Foams are classified as either rigid or flexible and are commonly used in applications such as pipe insulation, carpet fibers, and chair foam cushions. Polyurethane foams are excellent thermal insulators, have excellent mechanical properties, and are chemically inert. With the addition of fire protective additives, polyurethane foams have the ability to intumescence when exposed to high temperatures. For the future storage of the 9977 nuclear shipping packages, the material properties of the General Plastics 3716 rigid polyurethane foam were evaluated for long term performance by comparing aged samples to unaged samples. General Plastics 3716 rigid polyurethane foam was aged from November 2014 to June 2019 at varying temperatures of: 160 deg. F, 160 deg. F + 50% relative humidity (RH), 185 deg. F, 215 deg. F, and 250 deg. F. The foam was then analyzed via Fourier Transform Infrared Spectroscopy (FTIR), 3D Optical Microscope, Thermal Gravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC). FTIR and Optical Microscope: No significant change to chemical or physical structure was evident by FTIR or optical microscope analysis. DSC: Decrease of heat capacity over time for all oven temperatures except a slight increase for the 185 deg. F conditioned foams. Largest decrease evident with foams conditioned at 250 deg. F. A slight increase in heat capacity for humid samples. Similar trends in heat capacities at 71 deg. C and 102 deg. C. TGA: As conditioning temperature increased, a decline was evident in the average percent weight loss, onset temperature, and first derivative peak temperature. No significant effect due to humidity except for a decrease in first derivative peak temperature. Unaged samples exhibited strong intumescence. Foams conditioned at 160 deg. F exhibited slight intumescence. Results suggest fire protective additives decomposed at higher temperatures, which contributed to a lower average percent mass loss in higher temperature conditioning. Further thermal degradation testing would be beneficial to evaluate the ability of the conditioned foams to intumesce. Evaluate irradiation dose rate effects on conditioned foam. Possible conditioning in an environment with a known humidity or analyzing a new aliquot of sample for each trial to achieve a more representative heat capacity calculation.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2020

Verification of Reactor Activation Modelling with Physical Characterization Data and the Impact on Long Term Assessments - 20303

Whiteshell Laboratories, located in Manitoba, Canada, provided research facilities for the Canadian nuclear industry since the early 1960's. The facility was centered on Whiteshell Reactor 1 (WR-1), an organically cooled, heavy water moderated nuclear reactor. WR-1 was safely shut down in 1985, defueled and drained, and has been in a safe Storage with Surveillance (Deferred Decommissioning) state until present day. In support of an Environmental Assessment for proposed in-situ disposal of WR-1, detailed characterization information regarding the reactor core components (calandria, calandria tubes, and pressure tubes) was necessary to provide confidence that the long-term impacts of the facility can be assessed adequately. A simplified estimate of the total activation of core components was completed in 1992 using conservative assumptions, expected reactor configuration and computer models built with WIMS-CRNL, ONEDANT and ORIGEN-S. Due to the simplification, and age of the work, there was considerable doubt that the modelled inventory estimate of the core components was sufficient to support long-term performance modeling of the planned in-situ decommissioning. Additional data would be required to provide this confidence. Several options were considered for characterizing the WR-1 core components, but it was decided to collect only a limited number of samples in an effort to validate the 1992 simplified estimate as bounding. The limited number of samples reduced risks to workers, both radiological and non-radiological, and significantly reduced the costs required to confidently define and bound the radiological inventory of activation products in the core. The results of the sampling were compared to the simplified activation estimation. There was good agreement between the modelled and sampled results, with all major contributors to total activity showing similar relative quantities. The samples were generally lower than predicted by the models, with few exceptions. Notable exceptions included Nb-94, which were higher in the sample results than the model. This was determined to be caused by the use of Niobium containing steel alloys in the stainless steel pressure tube that were not accounted for in the models. The comparison of results provided confidence that the original inventory estimates produced through the simplified model are conservative and bounding, and therefore suitable for use in the long-term assessment of in situ disposal of the WR-1 reactor. This paper provides details of the simplified computer model results, their comparison to results of the sampling, and the changes adopted in the assessment of the in-situ decommissioning of WR-1 as a result. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2023

Post Irradiation Examination Results of Irradiated Yttrium Hydride

Department of Energy’s (DOE’s) Microreactor program (MRP) aims to provide the fundamental data to enable the development of microreactors. As such, material property data of critical materials for microreactor technologies are researched. Because substoichiometric yttrium dihydride (YHx, where x<2) is considered as a potential solid neutron moderator, its material property data has been combined in the Advanced Moderator Material Handbook which includes thermodynamic and thermophysical properties of YHx with the exception of irradiated material’s properties due to limited PIE. To fill the knowledge gap for the irradiated YHx, specimens and irradiation capsules were prepared at Los Alamos National Laboratory (LANL). Specimens were irradiated in the Advanced Test Reactor (ATR) at Idaho National Laboratory’s (INL’s). post-irradiation examination (PIE) was performed at INL’s Materials and Fuels Complex (MFC). This report compiles the PIE results of irradiated YHx specimens through fiscal years 2022 and 2023 (FY22-23) . The PIE data will directly be incorporated into the newer version of the Advanced Moderator Material Handbook. The main takeaways include that (i) the geometrical stability and mechanical integrity of YHx was intact with couple exceptions after high-temperature irradiations (600-800°C), (ii) hydrogen content variation due to manufacturing or irradiation in YHx caused visible surface discoloration, that is also related to the microstructural changes, (iii) qualitative comparisons of PIE methods implied that H retention was significantly higher at 600°C as compared to 800°C, (iv) thermal properties included signatures correlated with the H loss or re-gain, (v) importance of manufacturing readiness and initial as-manufactured specimens history was emphasized, (vi) the needs of targeted irradiations focusing on temperature and time parameters and very targeted PIE were specified.

08 HYDROGEN↗

DOE OSTI2023

Report on the Incorporation of Post-Irradiation Examination Results of Yttrium Hydride for Advanced Moderator Handbook

08 HYDROGEN↗

DOE OSTI2023

Successful cognitive aging is associated with thicker anterior cingulate cortex and lower tau deposition compared to typical aging

INTRODUCTION There is no consensus on either the definition of successful cognitive aging (SA) or the underlying neural mechanisms. METHODS We examined the agreement between new and existing definitions using: (1) a novel measure, the cognitive age gap (SA-CAG, cognitive-predicted age minus chronological age), (2) composite scores for episodic memory (SA-EM), (3) non-memory cognition (SA-NM), and (4) the California Verbal Learning Test (SA-CVLT). RESULTS Fair to moderate strength of agreement was found between the four definitions. Most SA groups showed greater cortical thickness compared to typical aging (TA), especially in the anterior cingulate and midcingulate cortices and medial temporal lobes. Greater hippocampal volume was found in all SA groups except SA-NM. Lower entorhinal 18 F-Flortaucipir (FTP) uptake was found in all SA groups. DISCUSSION These findings suggest that a feature of SA, regardless of its exact definition, is resistance to tau pathology and preserved cortical integrity, especially in the anterior cingulate and midcingulate cortices. Highlights: Different approaches have been used to define successful cognitive aging (SA). Regardless of definition, different SA groups have similar brain features. SA individuals have greater anterior cingulate thickness and hippocampal volume. Lower entorhinal tau deposition, but not amyloid beta is related to SA. A combination of cortical integrity and resistance to tau may be features of SA.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2016

Phase I/II Study of Radiofrequency Ablation for Malignant Renal Tumors: Japan Interventional Radiology in Oncology Study Group 0701

PurposeThis multicenter phase I/II study evaluated the safety, feasibility, and initial efficacy of radiofrequency ablation (RFA) for small malignant renal tumors.MethodsThirty-three patients were enrolled in the study. A single session of RFA was performed in patients with a renal tumor of 1–3 cm in greatest diameter, with the exception of lesions adjacent to the renal hilum. The primary endpoint was the safety of renal RFA, and the secondary endpoints were its feasibility and initial efficacy for local control, as well as the incidence and grade of adverse events. Clinical efficacy was evaluated by CT scans within 1 week and at a further 4 weeks after the procedure using the criteria adapted from the Response Evaluation Criteria in Solid Tumors.ResultsThe RFA procedure was completed in 100 % (95 % confidence interval [CI] 89–100 %) of all 33 patients. There were no severe adverse events (0 % [95 % CI 0–11 %]). Among the 33 patients, a complete response, partial response, progressive disease, and stable disease were seen in 28 (85 %), 0 (0 %), one (3 %), and one (3 %) patient(s), respectively, with a tumor response rate of 85 % [95 % CI 68–95 %]). Three patients (9 %), including one ineligible patient (3 %), were not evaluable. Out of 30 evaluable patients, a complete response was achieved in 28 (93 %).ConclusionThe current multicenter trial revealed that RFA is a safe, feasible, and effective treatment for small malignant renal tumors in patients who are not candidates for surgery.

62 RADIOLOGY AND NUCLEAR MEDICINE↗

DOE OSTI2021

Synthesis, characterization, and thermodynamic study of selected K-based zeolites

Potassium-rich zeolites often occur in cementitious systems, as K{sup +} is widespread in various cementitious materials, such as Portland, blended and alkali-activated cements. The knowledge of their stability and of thermodynamic models for solid solutions with Na{sup +} and Ca{sup 2+} are critical to understand long-term development and durability in such cements. Completing previous studies on Na- and Ca-based zeolites, the current work aims to determine the thermodynamic data of 14 types of K-based zeolites, which could possibly form in cementitious systems. The zeolites were synthesized hydrothermally, exchanged with K{sup +}, and characterized thoroughly with respect to framework structures, elemental compositions, water contents, and bond variations. Their thermodynamic properties were derived from the experimental solubility data, which allowed establishing predominance diagrams in the K{sub 2}O-SiO{sub 2}-Al{sub 2}O{sub 3}-H{sub 2}O system. The K-based zeolites typically showed the lowest solubility between 0 and 100 °C, with the notable exception of Ca-gismondine and two Na-based zeolites: natrolite and Na-mordenite.

36 MATERIALS SCIENCE↗

DOE OSTI2016

Hyperintensity in the Dentate Nucleus on Nonenhanced T1-Weighted Magnetic Resonance Imaging Suggests Dechelation of Contrast Agents

With the exception of renal failure patients, gadolinium-based contrast agents (GBCAs) for magnetic resonance imaging (MRI) have a high tolerance and acceptability in patients needing to undergo an enhanced MRI. Now that enhanced MRIs are becoming increasingly popular and nephrogenic systemic fibrosis cases are becoming a rarity, a common belief is that these GBCAs are essentially “biologically inert” materials. However, recent reports have emerged querying the link between these GBCAs and hyperintensity in the dentate nucleus on unenhanced T1-weighted MRI in some patients. This review article outlines the basic chemistry and characteristics of currently approved GBCAs, summarizes the described research findings of gadolinium deposition in the dentate nucleus, and identifies areas for future research.

62 RADIOLOGY AND NUCLEAR MEDICINE↗

DOE OSTI2017

Inflation model selection meets dark radiation

We investigate how inflation model selection is affected by the presence of additional free-streaming relativistic degrees of freedom, i.e. dark radiation. We perform a full Bayesian analysis of both inflation parameters and cosmological parameters taking reheating into account self-consistently. We compute the Bayesian evidence for a few representative inflation scenarios in both the standard ΛCDM model and an extension including dark radiation parametrised by its effective number of relativistic species N {sub eff}. Using a minimal dataset (Planck low-ℓ polarisation, temperature power spectrum and lensing reconstruction), we find that the observational status of most inflationary models is unchanged. The exceptions are potentials such as power-law inflation that predict large values for the scalar spectral index that can only be realised when N {sub eff} is allowed to vary. Adding baryon acoustic oscillations data and the B-mode data from BICEP2/Keck makes power-law inflation disfavoured, while adding local measurements of the Hubble constant H {sub 0} makes power-law inflation slightly favoured compared to the best single-field plateau potentials. This illustrates how the dark radiation solution to the H {sub 0} tension would have deep consequences for inflation model selection.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2015

SU-E-T-147: Beam Specific Planning Target Volumes Incorporating 4DCT for Pencil Beam Scanning Proton Therapy of Thoracic Tumors

Purpose: The purpose of this study is to determine whether organ sparing and target coverage can be simultaneously maintained for pencil beam scanning (PBS) proton therapy treatment of thoracic tumors in the presence of motion, stopping power uncertainties and patient setup variations. Methods: Ten consecutive patients that were previously treated with proton therapy to 66.6/1.8 Gy (RBE) using double scattering (DS) were replanned with PBS. Minimum and maximum intensity images from 4DCT were used to introduce flexible smearing in the determination of the beam specific PTV (BSPTV). Datasets from eight 4DCT phases, using ±3% uncertainty in stopping power, and ±3 mm uncertainty in patient setup in each direction were used to create 8*12*10=960 PBS plans for the evaluation of ten patients. Plans were normalized to provide identical coverage between DS and PBS. Results: The average lung V20, V5, and mean doses were reduced from 29.0%, 35.0%, and 16.4 Gy with DS to 24.6%, 30.6%, and 14.1 Gy with PBS, respectively. The average heart V30 and V45 were reduced from 10.4% and 7.5% in DS to 8.1% and 5.4% for PBS, respectively. Furthermore, the maximum spinal cord, esophagus and heart dose were decreased from 37.1 Gy, 71.7 Gy and 69.2 Gy with DS to 31.3 Gy, 67.9 Gy and 64.6 Gy with PBS. The conformity index (CI), homogeneity index (HI), and global maximal dose were improved from 3.2, 0.08, 77.4 Gy with DS to 2.8, 0.04 and 72.1 Gy with PBS. All differences are statistically significant, with p values <0.05, with the exception of the heart V45 (p= 0.146). Conclusion: PBS with BSPTV achieves better organ sparing and improves target coverage using a repainting method for the treatment of thoracic tumors. Incorporating motion-related uncertainties is essential This work was supported by the US Army Medical Research and Materiel Command under Contract Agreement No. DAMD17-W81XWH-07-2-0121 and W81XWH-09-2-0174.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2016

THE ORBIT AND MASS OF THE THIRD PLANET IN THE KEPLER-56 SYSTEM

While the vast majority of multiple-planet systems have orbital angular momentum axes that align with the spin axis of their host star, Kepler-56 is an exception: its two transiting planets are coplanar yet misaligned by at least 40° with respect to the rotation axis of their host star. Additional follow-up observations of Kepler-56 suggest the presence of a massive, non-transiting companion that may help explain this misalignment. We model the transit data along with Keck/HIRES and HARPS-N radial velocity data to update the masses of the two transiting planets and infer the physical properties of the third, non-transiting planet. We employ a Markov Chain Monte Carlo sampler to calculate the best-fitting orbital parameters and their uncertainties for each planet. We find the outer planet has a period of 1002 ± 5 days and minimum mass of 5.61 ± 0.38 M{sub Jup}. We also place a 95% upper limit of 0.80 m s{sup −1} yr{sup −1} on long-term trends caused by additional, more distant companions.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2016

Ultraviolet emission lines of Si ii in quasars—investigating the “Si ii disaster”

The observed line intensity ratios of the Si ii λ1263 and λ1307 multiplets to that of Si ii λ1814 in the broad-line region (BLR) of quasars are both an order of magnitude larger than the theoretical values. This was first pointed out by Baldwin et al., who termed it the “Si ii disaster,” and it has remained unresolved. We investigate the problem in the light of newly published atomic data for Si ii. Specifically, we perform BLR calculations using several different atomic data sets within the CLOUDY modeling code under optically thick quasar cloud conditions. In addition, we test for selective pumping by the source photons or intrinsic galactic reddening as possible causes for the discrepancy, and we also consider blending with other species. However, we find that none of the options investigated resolve the Si ii disaster, with the potential exception of microturbulent velocity broadening and line blending. We find that a larger microturbulent velocity (∼500 km s{sup −1}) may solve the Si ii disaster through continuum pumping and other effects. The CLOUDY models indicate strong blending of the Si ii λ1307 multiplet with emission lines of O i, although the predicted degree of blending is incompatible with the observed λ1263/λ1307 intensity ratios. Clearly, more work is required on the quasar modeling of not just the Si ii lines but also nearby transitions (in particular those of O i) to fully investigate whether blending may be responsible for the Si ii disaster.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2016

Two new SiO maser sources in high-mass star-forming regions

Silicon monoxide (SiO) masers are rare in star-forming regions, with the exception of five known SiO maser sources. However, we detected two new SiO maser sources from infrared-loud clumps of the high-mass star-forming regions G19.61−0.23 and G75.78+0.34. High angular resolution observations toward G19.61−0.23 suggest that the deeply embedded young stellar object (YSO) of SMA1 is powering the SiO masers. In addition, the SiO v = 1, J = 1 → 0 line shows four spike features, while the v = 2 maser shows combined features of one spike and broad wing components, implying energetic activities of the YSO of SMA1 in the G19.61−0.23 hot molecular core. The SiO v = 0, J = 2 → 1 emission shows bipolar outflows in the NE–SW direction with respect to the center of the SiO maser source. A high angular resolution map of the SiO v = 1, J = 2 → 1 maser in G75.78+0.34 shows that the SiO maser is associated with the CORE source at the earliest stage of high-mass star formation. Therefore, the newly detected SiO masers and their associated outflows will provide good probes for investigating this early high-mass star formation.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2016

INFRARED HIGH-RESOLUTION INTEGRATED LIGHT SPECTRAL ANALYSES OF M31 GLOBULAR CLUSTERS FROM APOGEE

Chemical abundances are presented for 25 M31 globular clusters (GCs), based on moderately high resolution ( R = 22,500) H -band integrated light (IL) spectra from the Apache Point Observatory Galactic Evolution Experiment (APOGEE). Infrared (IR) spectra offer lines from new elements, lines of different strengths, and lines at higher excitation potentials compared to the optical. Integrated abundances of C, N, and O are derived from CO, CN, and OH molecular features, while Fe, Na, Mg, Al, Si, K, Ca, and Ti abundances are derived from atomic features. These abundances are compared to previous results from the optical, demonstrating the validity and value of IR IL analyses. The CNO abundances are consistent with typical tip of the red giant branch stellar abundances but are systematically offset from optical Lick index abundances. With a few exceptions, the other abundances agree between the optical and the IR within the 1 σ uncertainties. The first integrated K abundances are also presented and demonstrate that K tracks the α elements. The combination of IR and optical abundances allows better determinations of GC properties and enables probes of the multiple populations in extragalactic GCs. In particular, the integrated effects of the Na/O anticorrelation can be directly examined for the first time.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2016

DISCOVERY OF A POSSIBLE COOL WHITE DWARF COMPANION FROM THE AllWISE MOTION SURVEY

We present optical and near-infrared spectroscopy of WISEA J061543.91-124726.8, which we rediscovered as a high motion object in the AllWISE survey. The spectra of this object are unusual; while the red optical ( λ > 7000 Å) and near-infrared spectra exhibit characteristic TiO, VO, and H{sub 2}O bands of a late-M dwarf, the blue portion of its optical spectrum shows a significant excess of emission relative to late-M-type templates. The excess emission is relatively featureless, with the exception of a prominent and very broad Na i D doublet. We find that no single, ordinary star can reproduce these spectral characteristics. The most likely explanation is an unresolved binary system of an M7 dwarf and a cool white dwarf. The flux of a cool white dwarf drops in the optical red and near-infrared, due to collision-induced absorption, thus allowing the flux of a late-M dwarf to show through. This scenario, however, does not explain the Na D feature, which is unlike that of any known white dwarf, but which could perhaps be explained via unusual abundance or pressure conditions.

79 ASTRONOMY AND ASTROPHYSICS↗