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The stress-corrosion cracking (SCC) behavior of U--6 wt percent Nb in three different heat-treated conditions was investigated. The three heat treatments were: (a) solution quenched (the nonaged condition); (b) solution quenched and aged 6 hours at 250/sup 0/C (the underaged condition); and (c) solution quenched and aged 80 minutes at 600/sup 0/C (the overaged condition). The SCC tests utilized smooth, dead-weight loaded, static tensile specimens exposed to nitrogen-saturated or oxygen-saturated water containing 50 ppM chloride ions. The alloy in the solution-quenched condition was not susceptible to SCC when loaded to 90 percent of yield strength in either the oxygen or nitrogen-saturated chloride solutions. The underaged material (6 hours at 250/sup 0/C) was susceptible to SCC in oxygen or nitrogen-saturated water containing 50 ppM chloride ions. The underaged material was more susceptible to cracking in the oxygen-saturated solution than in the nitrogen-saturated solutions. The SCC in the underaged material proceeded by a principally intercrystalline fracture mode with the overload condition being principally transgranular. The overaged material also exhibited SCC, but to a lesser extent than the underaged material. Here again, cracking was more pronounced in the oxygen-saturated solution than in the nitrogen-saturated solution. The overaged material fractured by a combined SCC …

A battery of statistical techniques are combined to improve detection of low-level dose response. First, Mahalanobis distances are used to classify objects as normal or abnormal. Then the proportion classified abnormal is regressed on dose. Finally, a subset of regressor variables is selected which maximizes the slope of the dose response line. Use of the techniques is illustrated by application to mouse sperm damaged by low doses of x-rays.

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A code, CACECO, has been written to assist in the analysis of containment situations peculiar to sodium cooled reactors. Typically, these situations involve relatively slow energy release processes and chemical reaction heat. Two examples are given to illustrate some of the code's features. These particular cases illustrate the potential for hydrogen formation in the containment building, but show that time is available to take corrective action. The code is suitable for other problems involving passive heat absorption in massive structures over long periods of time.

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Burzet is a proposed intermediate-yield underground test of a nuclear explosive at the Nevada Test Site. The possible existence of a high Paleozoic scarp and fault within 100 m of the proposed working point created concern as to their effect on the containment of the radioactive gases. A calculation of the expected stress wave interaction at the scarp and fault demonstrates that the effects are negligible. Results of the calculation are those expected from an event in a homogeneous media and are thus consistent with good containment experience on numerous previous detonations of similar yield, depth of burial, and medium properties.

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On March 13, 1979, a plutonium oxide storage can ruptured in the 303-C storage facility, which is in the 300 Area of the Hanford Site, Washington. The facility is operated by the Pacific Northwest Laboratory (PNL); three PNL staff members were performing the storage operation. No injuries to these staff members resulted from the occurrence. A Class C Investigation Committee was appointed on March 14, 1979, by the Director, PNL. Subsequently, when the loss estimates became available, the Manager, Department of Energy-Richland Operations Office (DOE-RL), appointed a Class B Investigation Committee in accordance with DOE Manual Chapter 0502. As requested by DOE-RL, the Committee investigated technical elements of the causal sequence and management systems that should have or could have prevented the occurrence. The investigation included: review of the use of the 303-C facilities and the transfer containers; interviews with the involved personnel and their managers; analysis of technical studies related to involved materials and procedures; review of safe operating procedures, radiation work procedures, and transfer requirements applicable to the occurrence; and use of the Management Oversight and Risk Tree (MORT) and the Events and Causal Factors Charting methods. 15 figs.