Modeling Contents and Leaks-Advantages and Limitations

During II meetings between Sept. 1987 and Sept. 1992 the Draft International Standard ISO/DIS 12807 \"Leakage testing on packages for the safe transport of radioactive materials\" has been developed and was published Nov. 1993. In July 1994 ISOffC 85 \"Nuclear Energy\"/SC 5 \"Nuclear Fuel Technology\"/WG 10 \"Leakage Testing ... \" under its chairman (Louis Tanguy, France) met again to resolve last questions and comments. End of March 1995 the final version (draft P) was submitted to the ISO Central Secretariat; ISO 12807 shall be issued May 1996. This International Standard should supersede the American National Standard N 14.5 for \"Leakage testing on packages for shipment of radioactive materials\" of 1977 (chairman William R. Taylor, Canada) and its revision of 1987 (chairman Larry Fischer, USA); both chairmen were active members of this new ISO working group. One negative tendency: ANSI Nl4.5-l977 included 5 \"Calculation Examples\" , ANSI N.l4.5-1987 34 (!!) \"Example Problems\", and ISO 12807 will include only 13 \"Worked Examples\" ; among others a new one about permeation (helium during leakage testing, and radioactive k.rypton-85 release at normal transport and accident conditions) as a German contribution. Further you will find comprehensive \"Explanatory notes\" on gas flow prepared by UK and German delegates. Within all three standards the \"one capillary\" leak model with laminar-viscous gas flow predominates. For a later revision of ISO 12807 we need some further worked examples! Supplementary now it seems useful to explain some features used in German licensing practice to achieve a more general acceptance and application.