RADIATION MEASUREMENTS--COMPARISON OF RADIOLYSIS EFFECTS OF COBALT-60 GAMMA RAYS AND 3-6 Mev ELECTRONS ON NITRILE SYSTEMS

Thesis/Dissertation · Mon Jan 01 04:00:00 EST 1962

OSTI ID:4682761

Miller, G H

The object of this investigation was to develop a liquid chemical dosimeter, useful in the dose range from 10/sup 6/ through 10/sup 8/ rads or above, using nitriles; to determine the type and yield of radiolysis products of the nitriles; and to determine whether the high instantaneous dose rate of electrons from it pulsed linear accelerator has a radiolysis effect different from that of gamma radiation from Co/sup 60/ as measured by changes in dosimeter products. High intensity gamma-ray and accelerated electron sources require liquid chemical dosimeters in the 10/sup 6/-10/sup 8/ rad range for accurate dose measurement of intended research samples. Previously, there has been no fully adequate liquid dosimeter throughout the 10/sup 8/ rad range. It has also been necessary to determine whether accelerated electrons, with up to 4.8 x 10/sup 5/ times the instantaneous dose rate of Co/sup 60/ gamma rays, would give the same G yield (molecules per 100 ev). Acetonitrile and benzonitrile were chosen as systeNonems for evaluation. The experimental results show that the radiolysis CN yields from purified nitriles are an exponential function of dose. Irradiation in sealed tubes, screw capped vials, underwater or in the air, gives substantially the same results, but sealed tuves in air are the most precise. Oxygen (air) and water in the samples alter the yield, but vessel size, temperature up to 140 deg F, light (visible and ultraviolet), and metals (Pt, Nichrome, Chromel A, stainless steel, Al, or Hg) do not. To measure absolute dose from the accelerator, a calorimeter was designed to absorb all of a collimated beam in the nitrile sample. The resulting temperature rise was converted to dose, and the chemical effect on the nitrile was determined. The electron and gamma radiation gave the same yield of hydrogen and under 10% difference in the CN yield. The methane yields were close but statistically different. The products were identified by a combination of mass spectrometry, high mass spectromnetry, infrared spectroscopy, nuclear magnetic resonance and gas chromotography. Their formation can be accounted for by radiation bond rupture, hydrogen abstraction and random free radical recombination. Benzonitrile was found to be very radiation resistant; the hydrogen and methane yields were only 2 to 3% of those from acetonitrile. The following conclusions are drawn: purified acetonitrile makes a satisfactory dosimeter over the range 1 x 10/sup 6/ to 6.5 x 10/sup 8/ rads; the wt % yield of CN is an exponential function of the total dose in megarads and is given by the equation: CN == 0.0050 (dose) /sub 0.8245/; the principal gaseous products are H/sub 2/(G = 0.58) and CH/sub 4/(G = 0.63) with minor yields of NH/sub 3/, C/sub 2/H/sub 6/, C/sub 2/ H/sub 2/, N/sub 2/, HCN, C/sub 3/H/sub 8/ and C/sub 4/ H/sub 10/; identified heavier products are C/sub 2/, C/sub 3/, and C/sub 4/, aliphatic nitriles, succinonitril e, malononitrile, and acetonitrile dimer (3-imino-butyronitrile); a complex polymer (G = 8) contains imine or imine and nitrile groups, the C-H--N proportions approach (CH//sub 3/CN)/sub x/ and the measured CN yield used in the dosimetry is largely contained in the polymer; benzonitrile is appreciably more radiation resistenat than acetonitrile and gives promise of a still higher level dosimeter; and the calorimetric method for absolute dose measurement is satisfactory and the accelerator radiation is not significantly different from the cobalt-60 radiation. (auth)

• Research Organization: Originating Research Org. not identified
• NSA Number: NSA-17-030887
• OSTI ID: 4682761
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

AIR
ALUMINUM
CHROMATOGRAPHY
CHROMEL
CHROMIUM ALLOYS
COBALT 60
CYANIDES
DECOMPOSITION
DOSEMETERS
ELECTRON BEAMS
ENERGY
FREE RADICALS
GAMMA RADIATION
HYDROCARBONS
HYDROGEN
INFRARED RADIATION
INSTRUMENTS AND INSTRUMENTATION
LIGHT
LINEAR ACCELERATORS
MASS SPECTROMETERS
MEASURED VALUES
MERCURY
METHANE
MOLECULES
NICHROME
NICKEL ALLOYS
NITRILES
PLATINUM
POLYMERS
QUANTITATIVE ANALYSIS
RADIATION CHEMISTRY
RADIATION DOSES
RADIATION EFFECTS
RADIATIONS
RADIOLYSIS
SEALS
STAINLESS STEELS
STATISTICS
TEMPERATURE
TUBES
ULTRAVIOLET RADIATION
WATER