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.     

Complications following major abdominal surgery in cirrhotic patients

The morbidity and mortality associated with major abdominal surgical interventions in 34 histologically proven cirrhotic patients are analyzed by the authors. The surgical interventions were carried out as urgent, absolute and elective indications. Thirty-seven general and surgical complications were observed following major abdominal surgery in 34 cirrhotics. Seven out of 34 patients died, giving a mortality rate of 21%. Suture-line insufficiency, peritonitis, sepsis and other inflammatory processes turned out to be the most common complications. Statistical analysis showed that the Child criteria, prothrombin level and white blood cell count were useful prognostic factors.     

Supraclavicular abscess caused by Salmonella enteritidis in patient without gastrointestinal symptoms

Soft tissue infections are among the rare manifestations of extra intestinal salmonellosis and occur more frequently in immunocompromised patients. Herein we report a case of a 51-year-old white male with type II. diabetes mellitus, diagnosed with supraclavicular abscess caused by Salmonella enteritidis. The patient denied any gastrointestinal symptoms, and stool cultures were negative. After incision, drainage, and administration of intravenous ampicillin (4 x 1.5 g/day for two weeks) the patient recovered completely. To our knowledge, this is the first reported case of cervical soft tissue abscess caused by Salmonella enteritidis without preceding gastrointestinal symptoms. We feel that the presence of diabetes was a risk factor for developing the infection.     

Evaluation of mycotoxin-contaminated cereals for their use in animal feeds in Hungary

In the period between December 5, 1991 and September 17, 1998, 760 maize, 367 wheat, 119 soybean, 222 barley, 85 bran, 32 triticale, 60 oat, 14 rye and 22 sunflower samples were investigated for the presence and concentration of seven fusariotoxins (T-2 toxin, zearalenone, deoxynivalenol, nivalenol, diacetoxyscirpenol, HT-2 toxin, fusarenone-X) and OTA. The comparison of analytical data with those of the relevant literature revealed that although the incidence rate and/ or concentration of Fusarium mycotoxins and OTA in Hungarian-grown cereals is occasionally considerable, the position of the country is not worse than the average of countries. Our findings indicate that soybean tends to be good substrate for trichothecene-producing fungi and the rate of contamination is regarded as substantial. The commodities were assorted into one of three quality categories. The proportion of objectionable samples was only 3.0, 2.2, 2.3 and 1.7% in maize, wheat, barley and soybean samples, respectively. However, this low rate of objection might still be a source of great economic loss. The proportion of objectionable samples was much higher in the case of bran, oat and triticale (7.1, 6.7, and 6.3%, respectively). The results of the present investigation indicate a need for regular screening for mycotoxins of importance and individual appraisal of each commodity from the point of their use in animal feeds.     

Realization of true-time delay lines based on acoustooptics

A true-time optical delay line for short radiofrequency (RF) pulses using path length dispersion is proposed. It is an optical implementation of the linear phase-shift theorem of the Fourier transformation. Acoustooptic signal processing is used for conversion into the optical frequency domain and for spatial Fourier decomposition of the pulse. The processing of the pulse is obtained by differentially phase shifting the particular frequency components, followed by a heterodyne reconversion into the RF domain. The optical system is intended to be used for delaying, but also for shaping and filtering of RF pulses, mainly in phased array radar antennas. Theoretical analysis of the system principle is given together with experimental results, demonstrating 2-μs time delay of 0.5-μs-long pulses with maximum optical phase shift of 1.2π. A detailed theoretical and experimental bandwidth analysis is carried out, pointing to the main technical problems and their solutions     

A new radiation-free conditioning in bone marrow transplantation and dibromo-mannitol therapy in chronic myeloid leukemia

A new, radiation-free, conditioning protocol, containing the original Hungarian mitobronitol (DBM) (DBM/ cytosine arabinoside/cyclosphosphamide) has been applied to 36 chronic myeloid leukemia (CML) patients followed by bone marrow transplantation (BMT) from HLA identical sibling donors between 1990-1997. In spite of some prognostically disadvantageous factors (half of them were above 40 years, 10 out of 36 patients were in accelerated phase, the disease history was longer than 2 years in average) the overall survival (30/36) and the leukemia free survival rate (26/36) were in accordance with the best international results. Transplantation-related toxicity was remarkably reduced in comparison to bone marrow transplantation performed by total body irradiation/cyclophosphamide (TBI/Cy) or busulphan/cyclophosphamide (Bu/Cy) conditioning protocols. Acute graft versus host disease was present in lower percentage (9/36) and the number of serious cases was only 2/36. Chronic GVH disease, generally known to be associated with antileukemic effect (GVL), occurred in 25 of cases. Early haematological relapse among the 34 patients with functioning graft occurred in 6 patients which rate is slightly higher than reported after TBI/Cy or Bu/Cy conditioning treatment. There was no relapse among patients transplanted within one year post-diagnosis and patients having CML with accelerated phase. The leukemia free post-transplant period was in association with the chronic GVH disease and full chimeric state.     

Efficiency of electro-hydrothermal coagulation in the management of non-variceal upper gastrointestinal bleeding

The data of 596 electro-hydrothermal coagulations in nonvariceal acute gastrointestinal bleeding were retrospectively evaluated and the results were compared to a previous period in which the endoscopic hemostasis was not regularly applied. Initial hemostasis was achieved in 96.1%, the rebleeding rate was 20.5%, perforation occurred in 0.5%. Comparing the two period the need of urgent surgery decreased from 9.2% to 3.4% (p < 0.05) and the mortality from 25.4% to 12% (p < 0.01). CONCLUSION: The electro-hydro-thermal coagulation is a safe and effective method in the treatment of nonvariceal gastrointestinal bleeding.     

On-demand release of corrosion-inhibiting ions from amorphous Al-Co-Ce alloys

Controlled release technologies are often used to supply chemicals or drugs at given rates. Release often occurs on contact with solution. However, some applications, such as corrosion protection, require containment of the active species in a reservoir and their slow release when needed. Conductive polymers have been used as reservoirs for corrosion inhibitors whose triggered release occurs by galvanic reduction or ion exchange. This work shows one of the first examples of pH-controlled release of corrosion-inhibiting ions from an amorphous metallic coating where the pH change that triggers release is a consequence of the onset of corrosion. This corrosion-inhibition strategy provides further corrosion protection beyond the traditional roles of barrier and sacrificial cathodic protection using a metal coating. For instance, zinc galvanizing provides sacrificial cathodic protection and acts as a barrier, but does not supply inhibitor ions. In the coating described here, protection of an underlying structural alloy exposed at coating defects is demonstrated by inhibitor ion release in addition to barrier function and sacrificial cathodic protection.