Pressure release of containments during severe accidents in Switzerland

As required by the Swiss Federal Nuclear Safety Inspectorate (HSK) all Switzerland's five nuclear power plants have to install a containment filtered venting system. The integrity of the containment (the last barrier for radioactive releases to the environment) can be threatened by overpressure due to inadequate heat removal. Design requirements have been provided for a specific class of severe accident scenarios. In general the capacity of the system is considered sufficient if it is able to vent the steam production corresponding to a decay heat level of 1% of the thermal reactor power. The mitigation capacity for the reduction of released radioactive material is specified by a retention factor of 1000 for aerosols to prevent or limit a long term ground contamination and a factor of 100 for elementary iodine for prevention or limiting of thyroid doses and to avoid short term evacuation. Besides existing requirements for design, maintenance and operation, additional claims such as passivity and operability at any pressure conditions inside the containment have to be met. Passivity implies that the system can be initiated after a severe accident without any operator action. The system also has to allow early manual venting. Various filtered venting systems are presently available. The nuclear power plants of Beznau, Gosgen, Leibstadt and Muhleberg have already selected such systems and already implemented them or are going to install them step by step. Beznau selected the Sulzer-EWI system which is using a water pool with nozzles-baffle plates and mixing elements to achieve the required filtration of the aerosols. In both Beznau units, the systems are installed and in standby mode. Gosgen, a pressurized water reactor as well as Beznau, is going to implement a filter system developed by Siemens-KWU, known as sliding pressure venting process, combining a venturi scrubber in a water pool and a mesh filter. The boiling water reactor of Leibstadt also selected the same system as Beznau while Müheberg choose the ABB system but not in the common design. The venturi pipes are thereby integrated in the water pool of the outer torus. The system in all five nuclear power plants is fully operable and in standby mode since December 1993.     

Effects of α‐form or β‐form nuclei on polymorphic crystalline morphology of poly(butylene adipate)

The effects of α‐form and β‐form nuclei on polymorphic morphology of poly(butylene adipate) (PBA) upon recrystallization from the molten state up to various T_max values were examined by differential scanning calorimetry (DSC), wide‐angle X‐ray diffraction (WAXD) and polarized light microscopy (PLM). In this study, PBA with complex melting and polymorphism behaviour was used as a model for examining different types and extents of residual nuclei. As the PBA initially containing the sole α‐crystal was brought to a molten state of various T_max, the extents of trace α‐form crystal nuclei varied and were dependent on T_max. Furthermore, it did not matter whether, initially, the PBA contained α‐ or β‐form crystals (or both) because only a single type of α‐nuclei could be left upon treatment to the molten liquid state at T_max. Therefore, only the α‐crystal in PBA had ‘memory capacity’ in the molten liquid state while the β‐crystal did not. This was so because the latter had been completely transformed into the solid state prior to being heated into a liquid. PBA crystallized before α‐nuclei could be packed into α‐crystal, regardless of the crystallization temperature (T_c). For recrystallization from molten PBA without any nuclei, the crystalline polymorphism was correspondingly influenced by T_c. Copyright © 2005 Society of Chemical Industry     

Heparin effect on hydrolysis of fibrin clots in a bull and a man with varying fibrinolytic systems

Heparin was studied for its effect on the hydrolysis time of clots from desAA fibrin (FB), desAABB fibrin (F0) and fibrinogen (Fg) of a bull and a man by gly-or lys-plasminogen which is activated by the tissue activator. It is shown that heparin in the concentration to 4.6 M does not affect that hydrolysis time of clots from human and bovine Fg and human Fg by gly-plasminogen which is activated by the tissue activator. Heparin increases the hydrolysis time of clots from bovine Fg and F0 by gly-and lys-plasminogen, the tissue activator being present. It firstly increases (in concentrations below 0.5 (microM), and then decreases (in concentrations above 0.5 (microM) the hydrolysis time of clots from human FB, F0 and Fg and bovine FB and F0 by plasmin. In concentration 4.6 microM heparin increases the hydrolysis time of clots from human fibrinogen by fibrinolytic systems. Effect of heparin on fibrinolytic process from the viewpoint of affine interactions between the components of fibrin clots is discussed.     

Symbiosis of nurse and machine through fuzzy logic: improved specificity of a neonatal pulse oximeter alarm

This article describes the theoretical underpinnings that preceded the design of a new neonatal pulse oximeter alarm that differentiates true from false alarms based on an artificial intelligence theory called "fuzzy logic." The connection between the intuition and sense of advocacy gained through neonatal primary nursing and the application of fuzzy logic to solve the problem of false alarms--that is, the symbiosis between nurse and machine--are explained. Emphasis is placed throughout on the importance of involving nurses in the development of the technology for which they are responsible.     

Alliance for destiny: education and practice

As the whole context of nursing continues to change radically in the face of unmet societal needs, nothing short of total revolution will suffice. Nurses must take control of nursing practice and be critical of the nation's inadequate "sick-care" system in order to effect sweeping changes in the scope, availability and efficacy of healthcare in the U.S. To do this requires an acknowledgment that true nursing education cannot exist without nursing practice. The transformation of curriculum must center on caring, which characterizes what nurses really do in a medically dominated system focused exclusively on curing.