er Paper Oxidation fard 1. Lee and Donald 1. Seaton, University of California Radiation Laboratory, Livermare, Calif.
fallout studies associated C with ’ Operation Hardtack required EaTAm
a method for the separation of radioactive particulate matter produced in a nuclear explosion from the filter medium on which samples aere collected. The filters used were pure cellulose paper reinforced with a cloth scrim and impregnated with stearic acid. Two methods were proposed: use of sonics to dislodge the particles from the paper, and removal of the paper from the particles hy oxidizing the organic material with some form of active oxygen. It is with the second of these two possibilities that this paper deals. Of the methods for producing atomic oxygen, two were selected as of possible use in this application. The first was the photodissociation of ozone. Under the conditions used in the preliminary experiments this method showed little promise. The second possibility, the diisociation of oxygen in ihigh-voltage alternating current glow dificharge, had been shown hy Turkevich (Turkevich, J., Chemistry Department, Prince
Figure 1. AI, A2. B. E. B.P. HzO.
ton University, private communication) to be effective in destroying very small amounts of cellulose. Repetition of this work, with provisions for handling larger samples, waa very encouraging. Approximately 12 sq. em. of paper could he destroyed completely in from 30 to 60 minutes. This system w a scaled up to handle papers up to 8 inches in diameter (Lee, E. L., Seaton, D. L., UCRL Rept. 5386). EXPERIMENTAL
The apparatus developed to effect the oxidation of the sample filters is shown in Figure 1. The hell jar, B, is g3/4 inches in inside diameter; the side arms, jacketed for water cooling, are 14 inches high; and the electrode chambers, AI and A?, are 1 inch in inside diameter and approximately 6 inches long. The discharge tube, T, is 10-nun. tubing. The electrodes, E, are water-cooled copper cylinders. A MacLeod gage measures the pressure of the system on the vacuum side of the paper, and a flowmeter is used in the
Full view of dissolver apparatus
Electrode chambers Bell 1r. Electrodes Base plate Water lines
L.M.
02.
T. T.T. T.T.M.
Lift m d o ~ Oxygen liner Discharge tube Turntable Turntable motor
Figure 2.
oxygen line on the high-pressure side of the inlet valves. The paper is laid on a grid, G, which is supported by a conical dish, D (Figure 2 ) . A Teflon ring sits on top of the paper and fits fairly close to the walls of the bell jar while still allowing m o v e ment. The oxygen flows into both arms of the discharge tube under approximately 8-mm. pressure and exits through slits in the tube extensions in the jar. This gives a “pie”-shaped distribution of atomic oxygen on the paper. Rotating the paper through 180’ effects complete destruction. Rotation is performed by driving the table with an electric motor and reduction gear train connected to a shaft which enters the hell jar through a Wilson seal in the base plate. The paper is rotated very slowly (-1 rotation per 3 hours). At higher rotational speeds the paper falls to pieces randomly and passes through the grid. Both arms of the discharge tube must he coated with phosphoric acid and then drained and dried. Phosphoric
Close-up view of discharge chamber B.
Bell ior
D. Colle
