Toward an internally consistent astronomical distance scale

Accurate astronomical distance determination is crucial for all fields in astrophysics, from Galactic to cosmological scales. Despite, or perhaps because of, significant efforts to determine accurate distances, using a wide range of methods, tracers, and techniques, an internally consistent astronomical distance framework has not yet been established. We review current efforts to homogenize the Local Group's distance framework, with particular emphasis on the potential of RR Lyrae stars as distance indicators, and attempt to extend this in an internally consistent manner to cosmological distances. Calibration based on Type Ia supernovae and distance determinations based on gravitational lensing represent particularly promising approaches. We provide a positive outlook to improvements to the status quo expected from future surveys, missions, and facilities. Astronomical distance determination has clearly reached maturity and near-consistency.Comment: Review article, 59 pages (4 figures); Space Science Reviews, in press (chapter 8 of a special collection resulting from the May 2016 ISSI-BJ workshop on Astronomical Distance Determination in the Space Age

High-burnup performance of mixed-oxide fuel rods clad in type 316SS of 0. 010- and 0. 015-inch wall thickness. [LMFBR]

Two short mixed-oxide fuel rods of LMFBR design configuration were irradiated to a burnup of approx. 12.5 atom % in GETR. Profilometry at several intervals during the test indicated that the rod with a 0.010 inch thick cladding exhibited a diametral strain of 0.17% per atom % burnup, while the rod with a 0.015 inch thick cladding exhibited a lower diametral strain rate of 0.12% per atom % burnup. These data present the opportunity for analytical methods to evaluate fuel rod dimensional changes without the complicating effect of metal swelling. Also, the rods incorporated a large plenum space so that pressure from released fission gases was extremely low. These measured strain rates are consistent with the range of fuel diametral strain rates that are associated with solid fission product swelling