Acoustic emission technique for leak detection in an end shield of a pressurised heavy water reactor

This paper discusses the successful application of the Acoustic Emission Technique (AET) for detection and location of leak paths present on the inaccessible side of an end shield of a Pressurised Heavy Water Reactor (PHWR). The methodology was based on the fact that air and water leak AE signals have different characteristic features. Baseline data was generated from a sound end-shield of a PHWR for characterizing the background noise. A mock up end-shield system with saw cut leak paths was used to verify the validity of the methodology. It was found that air leak signals under pressurisation (as low as 3 psi) could be detected by frequency domain analysis. Signals due to air leaks from various locations of a defective end-shield were acquired and analysed. It was possible to detect and locate leak paths. Presence of detected leak paths were further confirmed by alternate test.     

On ochratoxin A and fungal flora in Polish cereals from conventional and ecological farms. Part 2: occurrence of ochratoxin A and fungi in cereals in 1998.

Over 200 samples of Polish cereal grain from the 1998 harvest obtained from conventional and ecological farms were investigated for the presence of ochratoxin A and for contamination by microscopic fungi. The frequency of contamination of rye and barley grains from conventional and ecological farms was similar in most cases; it varied from nearly 5 to 12%, respectively, for both types of farming. However, in samples from ecological farms, higher maximum concentrations of ochratoxin A were observed (35 micro g kg(-1), overall range 1.4-35.3 micro g kg(-1)) for both cereals rye and barley in comparison with rye and barley from conventional farms (maximum levels of 8.8 and 9.7 micro g kg(-1), respectively). However, wheat grain from the conventional farms showed ochratoxin A concentrations in a very wide range from 0.6 to 1024 micro g kg(-1) and the average frequency of contaminated samples was about 48%. In contrast, in wheat samples from ecological farming, the presence of ochratoxin A ranged from 0.8 to 1.6 micro g kg(-1) (mean 1.2 micro g kg(-1)) and the frequency of contamination was 23%. From samples containing detectable amounts of ochratoxin A, fungi producing ochratoxin A under laboratory conditions were isolated. They were classified as belonging to the species Penicillium cyclopium, P. viridicatum, Aspergillus ochraceus group, A. glaucus and A. versicolor. Penicillium strains-species known to be producers of ochratoxin A-were isolated from 71% of the samples; in 28% of samples, only Aspergillus strains (species known to be producers of this mycotoxin) were noted. These results have been compared with those obtained in 1997.     

A vibratory filtration model for candle-type filters

A candle filter was used to determine flow rate characteristics of filtering suspensions under axial vibrations. In this work, a generalised analysis of filtration under vibrating conditions was developed. The model required the use of experimental data interpretation. The analysis gives in a simplified form the complicated functional relationship between time, cumulative flow, vibration parameters and other process variables.Such a relationship can be used in the design of vibratory filters for predicting flow rate with time. These filters are useful in particle separation processes.