61 research outputs found
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Trial application of the worker safety assessment methodology
A Worker Safety Assessment Methodology has been developed to assess the risks to workers from radiological accidents at non-reactor nuclear facilities. The methodology utilizes Process Hazards Analysis, proposed risk goals, and Quantitative Risk Analysis. The first phase of a trial application of the methodology to a nuclear facility has been completed and is being reports
Risk-Based Approach to Analyzing Operating Events
Existing programs for the analysis of operating events at the Department of Energy (DOE) facilities do not determine risk measures for the events. An approach for the risk based analysis of operating events has been developed, and applied to two events. The approach utilizes the data now being collected in existing data programs and determines risk measures for the events which are not currently determined. Such risk measures allow risk appropriate responses to be made to events, and provide a means for comparing the safety significance of dissimilar events at different facilities
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A Performance Indicator for Reduction in Vulnerability Through Stabilization of Plutonium
The US Department of Energy (DOE) is currently storing several metric tons of plutonium in various forms in a variety of facilities throughout the DOE complex. Since the cessation of weapons production in 1990, many of these facilities with plutonium in storage have not operated. Since the shutdown was regarded as temporary, little attempt was made at that time to empty the process lines of plutonium, or to place the plutonium in containers or packages that would provide safe storage for extended periods of time. As a result, the packages and containers providing interim storage are vulnerable to failure through leakage, rupture and other modes, and pose potential hazards to facility workers, the public and the environment. Here, an approach to measuring and tracking the reduction in vulnerabilities resulting from stabilizing and repackaging plutonium is developed and presented. The approach utilizes results obtained by the DOE Working Group on the vulnerabilities associated with plutonium storage
Nuclear uncertainties in the NeNa-MgAl cycles and production of 22Na and 26Al during nova outbursts
Classical novae eject significant amounts of nuclear processed material into
the interstellar medium. Among the isotopes synthesized during such explosions,
two radioactive nuclei deserve a particular attention: 22Na and 26Al. In this
paper, we investigate the nuclear paths leading to 22Na and 26Al production
during nova outbursts by means of an implicit, hydrodynamic code that follows
the course of the thermonuclear runaway from the onset of accretion up to the
ejection stage. New evolutionary sequences of ONe novae have been computed,
using updated nuclear reaction rates relevant to 22Na and 26Al production.
Special attention is focused on the role played by nuclear uncertainties within
the NeNa and MgAl cycles in the synthesis of such radioactive species. From the
series of hydrodynamic models, which assume upper, recommended or lower
estimates of the reaction rates, we derive limits on the production of both
22Na and 26Al. We outline a list of nuclear reactions which deserve new
experimental investigations in order to reduce the wide dispersion introduced
by nuclear uncertainties in the 22Na and 26Al yields.Comment: 46 pages, 4 figures. Accepted for publication in The Astrophysical
Journa
Cholesterol Corrects Altered Conformation of MHC-II Protein in Leishmania donovani Infected Macrophages: Implication in Therapy
Previously we reported that Kala-azar patients show progressive decrease in serum cholesterol as a function of splenic parasite burden. Splenic macrophages (MΦ) of Leishmania donovani (LD) infected mice show decrease in membrane cholesterol, while LD infected macrophages (I-MΦ) show defective T cell stimulating ability that could be corrected by liposomal delivery of cholesterol. T helper cells recognize peptide antigen in the context of
class II MHC molecule. It is known that the conformation of a large number of membrane proteins is dependent on membrane cholesterol. In this investigation we tried to understand the influence of decreased membrane cholesterol in I-MΦ on the conformation of MHC-II protein and peptide-MHC-II stability, and its bearing on the antigen specific T-cell activatio
Biogenic gas nanostructures as ultrasonic molecular reporters
Ultrasound is among the most widely used non-invasive imaging modalities in biomedicine, but plays a surprisingly small role in molecular imaging due to a lack of suitable molecular reporters on the nanoscale. Here, we introduce a new class of reporters for ultrasound based on genetically encoded gas nanostructures from microorganisms, including bacteria and archaea. Gas vesicles are gas-filled protein-shelled compartments with typical widths of 45–250 nm and lengths of 100–600 nm that exclude water and are permeable to gas. We show that gas vesicles produce stable ultrasound contrast that is readily detected in vitro and in vivo, that their genetically encoded physical properties enable multiple modes of imaging, and that contrast enhancement through aggregation permits their use as molecular biosensors
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Use of probabilistic safety analyses in severe accident management
An important consideration in the development and assessment of severe accident management strategies is that while the strategies are often built on the knowledge base of Probabilistic Safety Analyses (PSA), they must be interpretable and meaningful in terms of the control room indicators. In the following, the relationships between PSA and severe accident management are explored using ex-vessel accident management at a PWR ice-condenser plant as an example. 2 refs., 1 fig., 3 tabs
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