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Technical safety requirements control level verification
A Technical Safety Requirement (TSR) control level verification process was developed for the Tank Waste Remediation System (TWRS) TSRs at the Hanford Site in Richland, WA, at the direction of the US. Department of Energy, Richland Operations Office (RL). The objective of the effort was to develop a process to ensure that the TWRS TSR controls are designated and managed at the appropriate levels as Safety Limits (SLs), Limiting Control Settings (LCSs), Limiting Conditions for Operation (LCOs), Administrative Controls (ACs), or Design Features. The TSR control level verification process was developed and implemented by a team of contractor personnel with the participation of Fluor Daniel Hanford, Inc. (FDH), the Project Hanford Management Contract (PHMC) integrating contractor, and RL representatives. The team was composed of individuals with the following experience base: nuclear safety analysis; licensing; nuclear industry and DOE-complex TSR preparation/review experience; tank farm operations; FDH policy and compliance; and RL-TWRS oversight. Each TSR control level designation was completed utilizing TSR control logic diagrams and TSR criteria checklists based on DOE Orders, Standards, Contractor TSR policy, and other guidance. The control logic diagrams and criteria checklists were reviewed and modified by team members during team meetings. The TSR control level verification process was used to systematically evaluate 12 LCOs, 22 AC programs, and approximately 100 program key elements identified in the TWRS TSR document. The verification of each TSR control required a team consensus. Based on the results of the process, refinements were identified and the TWRS TSRs were modified as appropriate. A final report documenting key assumptions and the control level designation for each TSR control was prepared and is maintained on file for future reference. The results of the process were used as a reference in the RL review of the final TWRS TSRs and control suite. RL concluded that the TSR control level verification process is clear and logically based upon DOE Order 5480.22, Technical Safety Requirements, and other TSR control selection guidelines. The process provides a documented, traceable basis for TSR level decisions and is a valid reference for preparation of new TSRs
Neutron-diffraction study of field-induced transitions in the heavy-fermion compound Ce2RhIn8
We present neutron diffraction measurements in high magnetic fields (0 to
14.5 T) and at low temperatures (2.5, 2.3, 0.77 and 0.068 K) on single crystals
of the tetragonal heavy fermion antiferromagnet Ce2RhIn8. For B//[110] the
field dependence of selected magnetic and nuclear reflections reveals that the
material undergoes several transitions, the temperature dependence of which
suggests a complex B-T phase diagram. We present the detailed evolution of the
integrated intensities of selected reflections and discuss the associated
field-induced transitions.Comment: 12 pages, 3 figures Proceeding Euro-conference "Properties of
Condensed Matter probed by x-ray and neutron scattering"; to appear in
Physica
Theory and experiment of the ESR of Co in Zn % (OH)PO and Mg(OH)AsO
Experiments of Electron Spin Resonance (ESR) were performed on Co
substituting Zn or Mg in powder samples of Zn(OH)PO and
Mg(OH)AsO. The observed resonances are described with a theoretical
model that considers the departures from the two perfect structures. It is
shown that the resonance in the penta-coordinated complex is allowed, and the
crystal fields that would describe the resonance of the Co in the two
environments are calculated. The small intensity of the resonance in the
penta-coordinated complex is explained assuming that this site is much less
populated than the octahedral one; this assumption was verified by a molecular
calculation of the energies of the two environments, with both Co and Zn as
central ions in Zn(OH)PO.Comment: 43 pages, LaTex file, 6 figures, EPS. submitted to Journal of Physics
Condens
A source of a quasi--spherical space--time: The case for the M--Q solution
We present a physically reasonable source for an static, axially--symmetric
solution to the Einstein equations. Arguments are provided, supporting our
belief that the exterior space--time produced by such source, describing a
quadrupole correction to the Schwarzschild metric, is particularly suitable
(among known solutions of the Weyl family) for discussing the properties of
quasi--spherical gravitational fields.Comment: 34 pages, 9 figures. To appear in GR
Specific pathway abundances in the neonatal calf faecal microbiome are associated with susceptibility to Cryptosporidium parvum infection: a metagenomic analysis.
Cryptosporidium parvum is the main cause of calf scour worldwide. With limited therapeutic options and research compared to other Apicomplexa, it is important to understand the parasites' biology and interactions with the host and microbiome in order to develop novel strategies against this infection. The age-dependent nature of symptomatic cryptosporidiosis suggests a link to the undeveloped immune response, the immature intestinal epithelium, and its associated microbiota. This led us to hypothesise that specific features of the early life microbiome could predict calf susceptibility to C. parvum infection. In this study, a single faecal swab sample was collected from each calf within the first week of life in a cohort of 346 animals. All 346 calves were subsequently monitored for clinical signs of cryptosporidiosis, and calves that developed diarrhoea were tested for Rotavirus, Coronavirus, E. coli F5 (K99) and C. parvum by lateral flow test (LFT). A retrospective case–control approach was taken whereby a subset of healthy calves (Control group; n = 33) and calves that went on to develop clinical signs of infectious diarrhoea and test positive for C. parvum infection via LFT (Cryptosporidium-positive group; n = 32) were selected from this cohort, five of which were excluded due to low DNA quality. A metagenomic analysis was conducted on the faecal microbiomes of the control group (n = 30) and the Cryptosporidium-positive group (n = 30) prior to infection, to determine features predictive of cryptosporidiosis. Taxonomic analysis showed no significant differences in alpha diversity, beta diversity, and taxa relative abundance between controls and Cryptosporidium-positive groups. Analysis of functional potential showed pathways related to isoprenoid precursor, haem and purine biosynthesis were significantly higher in abundance in calves that later tested positive for C. parvum (q ≤ 0.25). These pathways are either absent or streamlined in the C. parvum parasites. Though the de novo production of isoprenoid precursors, haem and purines are absent, C. parvum has been shown to encode enzymes that catalyse the downstream reactions of these pathway metabolites, indicating that C. parvum may scavenge those products from an external source. The host has previously been put forward as the source of essential metabolites, but our study suggests that C. parvum may also be able to harness specific metabolic pathways of the microbiota in order to survive and replicate. This finding is important as components of these microbial pathways could be exploited as potential therapeutic targets for the prevention or mitigation of cryptosporidiosis in bovine neonates
Collisional equilibrium, particle production and the inflationary universe
Particle production processes in the expanding universe are described within
a simple kinetic model. The equilibrium conditions for a Maxwell-Boltzmann gas
with variable particle number are investigated. We find that radiation and
nonrelativistic matter may be in equilibrium at the same temperature provided
the matter particles are created at a rate that is half the expansion rate.
Using the fact that the creation of particles is dynamically equivalent to a
nonvanishing bulk pressure we calculate the backreaction of this process on the
cosmological dynamics. It turns out that the `adiabatic' creation of massive
particles with an equilibrium distribution for the latter necessarily implies
power-law inflation. Exponential inflation in this context is shown to become
inconsistent with the second law of thermodynamics after a time interval of the
order of the Hubble time.Comment: 19 pages, latex, no figures, to appear in Phys.Rev.
A comparison of the galling wear behaviour of PVD Cr and electroplated hard Cr thin films
Electroplated hard chromium (EPHC) is used in many industries as a wear and corrosion resistant coating. However, the long term viability of the electroplating process is at risk due to legislation regarding the toxic chemicals used. The physical vapour deposition (PVD) process has been shown to produce chromium and chromium-based coatings that could be a possible alternative for EPHC in some applications. This study investigates the microstructure and properties of two PVD chromium coatings as a possible alternative to EPHC to provide resistance to galling. Two PVD deposition processes are investigated, namely electron beam PVD (EBPVD) and unbalanced magnetron sputtering (UMS). Galling wear tests were performed according to ASTM G98-17. The results show that the two PVD coatings are of similar hardness, surface roughness and exhibit similar scratch behaviour. However, the galling wear resistance of the coating deposited by UMS is approximately ten times that of the EBPVD coating, and similar to that of the EPHC. X-ray diffraction reveals that the EBPVD chromium coating has a strong preferred orientation of the {200} planes parallel to the coating surface whilst in the UMS PVD coating, preferred orientations of the {110} and {211} planes parallel to the surface are observed. The EPHC does not exhibit relative peak intensities which conform to the International Centre for Diffraction Data (ICDD) powder diffraction pattern consistent with chromium. The crystal orientation of the PVD chromium coatings appears to play a significant role in influencing galling resistance
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