Report of the annual conference on weights and measures, hosted by the U.S. National Bureau of Standards in Washington D.C. It includes conference proceedings, a list of attendees, information about committees and officers, and other reports or commentaries discussed at the meetings.

Introduction: "This is the tenth letter report on ARF Project C 127, entitled "Preliminary Studies of Scavenging Systems Related to Radioactive Fallout." This report covers the period from October 1 to December 1, 1959."

Abstract: "In a study of the preparation and properties of delta-phase zirconium hydride it was found that large, sound bodies of the hydride can be prepared by direct combination of the elements if the rate of the reaction is retarded by limiting the supply of available hydrogen. Specimens up to 1-in. diameter were prepared using this technique. Because delta phase zirconium hydride does not readily form eutectics with iron-and nickel-base alloys below 1800 F these materials may be utilized for clodding the hydride. Delta-phase zirconium hydride is unaffected by exposure to liquid NaK or to nitrogen gas at temperatures below 1000 F. The hot hardness of delta-phase zirconium hydrid is about 130 kg per mm-2 at room temperature and 40 kg per mm-2 at 1500 F. The mean coefficient of thermal expansion (68 to 1337 F) is 6.5 x 10^-6 per deg F. The thermal conductivity varies from 5.7 Btu/(ft)(hr)(F) at 300 F to 5.1 Btu/(ft)(hr)(F) at 1300 F."

The PRP Critical Facility is an experimental reactor for use in determination of basic nuclear constants of heterogenous reactors recycling plutonium, and exponential and criticality studies at power levels up to 100 watts and neutron fluxes of about 109 nv. Provision is made for changing reactor lattices using irradiated and unirradiated fuel elements with either a light or heavy water moderator.

Report documenting the suitability of Nevada for plant locations to produce synthetic liquid fuels, based on raw materials, water sources, and local interest.

Experience in handling and purifying rubidium metal, prior to high-temperature corrosion testing, has been obtained. Some of the physical and chemical properties of this metal are listed. Distillation and filtration experiences are described, and the analysis of samples following such purification procedures are given. Stripping procedures following corrosion testing are discussed briefly. Results of preliminary corrosion experiments indicate that Inconel in a satisfactory container material for boiling rubidium at temperatures up to 1520°F.