periodically the Industrial Hygiene Unit has the occasion to perform efficiency tests on respiratory protective devices and on filter cartridges used with these units. A study of the relative merits of the flame photometer and conductivity meter was made to determine which is more applicable for the determination of NaCl in filter samples.

In order to utilize the advantages of the electron microscope for the study of respirable particles, it is desirable to have an instrument capable of sampling from atmospheres having very sparse dispersions of particles at a rate sufficiently high to result in precipitation densities of approximately one particle per 10/u² of microscope screen for a 10 minute sampling period. In order to avoid qualitative or quantitative alteration of the aerosol, it was desired that the instrument collect the sample directly on an electron microscope screen rather than on a filter material for subsequent transfer to the screen. This paper summarizes work aimed at the development of such an instrument.

This work was performed to develop a general chemical method for the determination of small amounts of plutonium in solution. The work showed that a coulometric titration based on the preliminary oxidation of the plutonium to Pu (VI) followed by titration with electrolytically-generated ferrous ion to Pu (IV) was such a general method and was subject to few interferences. The significance of the work is that a chemical determination of plutonium can be made for amounts of plutonium heretofore determined only by radioassay methods, and the chemical determination of larger amounts are made more readily and with higher precision than with previous methods. The work also extends the application of coulometric titration methods to a new substance.

The object of this study was to determine whether agitation with ultrasonic energy would significantly increase the dissolution rate of nickel in nitric acid.

R. H. Fillnow and H. Pennington of WAPD visited HAPO on September 14-15, 1955, to discuss HAPO special irradiation facilities and review fuel element problems with HAPO personnel. During their meeting with Metallurgy Research personnel, the progress of the evaluation of UO₂ elements for the PWR and the results of recent HAPO irradiations of oxide type fuel elements were discussed. Although brief, this information exchange was particularly valuable as many of the problems associated with the application of oxide fuel materials was reviewed. A summary of these discussions is outlined below.

Relations governing the measurement of Stainless Steel corrosion rates by activation analysis are derived and discussed. The principal neutron induced radioactivities are calculated and graphed. Shielding requirements are considered and it is concluded that six inches of lead shielding should be sufficient for the proposed experiments if the samples are allowed to cool for one day in the reactor storage basin.

This report describes a proposed modification to the ventilation system in the Redox Canyon Building. Detailed drawings and cost estimates are provided for three alternatives.

The design notes contained herein may assist in preliminary studies concerning feasibility of any proposed gamma monitor system. The minimum and maximum solution concentrations for each type of system are listed. The data is based on 32 ml liquid sample.

The purposes of this study are to review the available information affecting the disposal of Purex cooling water, powerhouse waste water, and B plant cooling water, to consider the feasibility of various disposal schemes, and to prepare recommendations to the Manufacturing Department for the most desirable courses of action.