This report discusses the state of stress caused by pressure in process tubes, elaborating on five "theories of failure" that each explain the stress in process tubes in a different manner. These theories, which are depicted in a graph, include maximum normal stress, maximum strain, maximum shear stress, maximum strain energy, and maximum strain energy of distortion.

The four types of respirator cartridges used at the 202 S Building were tested against aerosols found at that location, and in the laboratory against non-radioactive gaseous ruthenium tetroxide. Positive penetration of two types of cartridges was shown with one process aerosol. Gaseous ruthenium tetroxide penetrated all types of cartridges tested. Leaks were found in some of the cartridges. Particle size of aerosol particles was measured by means of cascade impactor samples and electron photomicrographs. A high percentage of the aerosol particles was found to be less than 0.2 microns in diameter. Ru¹⁰³ + Ru¹⁰⁶ and Zr⁹⁵ + Nb⁹⁵ were shown to be present in the process aerosol by gamma ray spectrometer analysis. Possible causes of penetration of respiratory equipment by ruthenium are discussed and suggestions made for alleviating the problem.