The detection of sodium vapor bubble collapse in a liquid metal fast breeder reactor

Sodium boiling detection utilizing the sound pressure emanated during the collapse of a sodium vapor bubble in a subcooled media is discussed in terms of the sound characteristic, the reactor ambient noise background, transmission loss considerations and performance criteria. Data obtained in several loss of flow experiments on Fast Test Reactor Fuel Elements indicate that the collapse of the sodium vapor bubble depends on the presence of a subcooled structure or sodium. The collapse pressure pulse was observed in all cases to be on the order of a kPa, indicating a soft type of cavitational collapse. Spectral examination of the pulses indicates the response function of the test structure and geometry is important. The sodium boiling observed in these experiments was observed to occur at a low (<50°C) liquid superheat with the rate of occurrence of sodium vapor bubble collapse in the 3 to 30 Hz range. Reactor ambient noise data were found to be due to machinery induced vibrations, flow induced vibrations, and flow noise. These data were further found to be weakly stationary enhancing the possibility of acoustic surveillance of an operating Liquid Metal Fast Breeder Reactor. Based on these noise characteristics and extrapolating the noise measurements from the Fast Flux Test Facility Pump (FFTP), one would expect a signal to noise ratio of up to 20 dB in the absence of transmission loss. The requirement of a low false alarm probability is shown to necessitate post detection analysis of the collapse event sequence and the cross correlation with the second derivative of the neutronic boiling detection signal. Sodium boiling detection using the sounds emitted during sodium vapor bubble collapse are shown to be feasible but a need for in-reactor demonstration is necessary.     

Potential U.S. contributions to in-reactor experiments for fast reactor surveillance systems

It is maintained that special features of FFTF make it an ideal system to test sodium boiling detection techniques by acoustic/neutronic methods and to test the response of acoustic/neutronic sensors to vibrations. It is shown that accumulated research results indicate that such tests in FFTF are feasible, predictable, promising and safe.     

The role of microstructure in hydrogen-assisted fracture of 7075 aluminum

Underaged, peak strength (T6), and overaged (T73) microstructures were studied in 7075 plate material. Hydrogen charged and uncharged tensile specimens of longitudinal orientation were tested between −196°C and room temperature. The results confirm a hydrogen embrittlement effect, manifested mainly in the temperature dependence of the reduction of area loss; a classical behavior of hydrogen embrittlement. The maximum embrittlement shifted to lower temperatures with further aging. The effect of hydrogen was largest for the underaged condition and smallest for the overaged, thus following the pattern found for the sensitivity to stress-corrosion cracking in high strength aluminum alloys. The fracture path was predominantly transgranular, with minor amounts of intergranular fracture. J. ALBRECHT, formerly with the Department of Metallurgy and Materials Science, Carnegie-Mellon University     

Einfluß des Phosphors auf die Korrosionsgeschwindigkeit weicher,unlegierter Stähle in verdünnter Schwefelsäure

Einfluß von Phosphor auf den zeitlichen Verlauf der Korrosionsgeschwindigkeit am Ruhepotential beim Beizen in verdünnter Schwefelsäure. Unstetigkeit der Stromdichte-Potential-Kurve bei Stählen mit hohen Phosphorgehalten durch Deckschichtbildung. Untersuchungen zum Aufbau und zur chemischen Zusammensetzung der Deckschicht.     

Clinical relevance of lithium determination in RBC: results of a catamnestic study (author's transl)]

In 34 out-patients Li+- and K+-concentrations were determined in plasma and RBC during 15 months of clinical routine observations. Average frequency of check-ups was 9/patient. Psychopathological state and side effects were documented by the AMP-system. The mean intra-extracellular lithium concentration ratio (LiQ) was 34%. The ratio and the absolute lithium RBC concentration showed a wide intraindividual variability between 5 and 53%. Patients under 50 years old had the same absolute concentration values as the older ones but required a 50% higher average dose. Side effects such as tremor and thirst correlated well the intra-extracellular ratio. No difference was found between unipolar and bipolar depressions. LiQ was slightly reduced and KQ increased in patients with severe relapses or additional psychotropic medication.     

Chromatin proteins of large and small brain nuclei

A simple fluorometric assay for monoamine oxidase (MAO) [EC 1.4.3.4] activity towards beta-phenylethylamine (PEA) was devised. The procedure consists in measuring the disappearance of PEA fluorometrically. The disappearance of PEA was completely inhibited by pargyline, a potent inhibitor of MAO. MAO activity for PEA was linear with 10 mg to 100 mg of liver tissue in 3 ml of reaction mixture for up to 90 min of incubation. Using this method, the V max values and the apparent Km values of MAO for PEA in several rat tissues were determined, and compared with those for benzylamine and 5-hydroxytryptamine (5-HT).