Document Details


Title:
EFFECTIVE ATTENUATION COEFFICIENTS FOR GAMMA EXPOSURE RATE CALCULATIONS: URANIUM-235 FISSION PRODUCT SOURCES IN AIR-WATER MEDIA
Author(s):
YOUNG, F H [UNITED STATES NAVAL RADIOLOGICAL DEFENSE LABORATORY]
Subject Terms:
GAMMA RADIATION; UNDERWATER EXPLOSIONS; URANIUM 235; FISSION; PHOTONS; DOSE RATES; CALCULATION METHODS
Document Location:
Location - NNSA/NSO Nuclear Testing Archive Address - P.O. Box 98521 City - Las Vegas State - NV Zip - 89193-8521 Phone - (702)794-5106 Fax - (702)862-4240 Email - CIC@NV.DOE.GOV
Document Type:
REPORT
Publication Date:
1968 Jan 24
Declassification Status:
Unknown
Document Pages:
0051
Accession Number:
NV0060360
Document Number(s):
USNRDLTR6849
Originating Research Org.:
UNITED STATES NAVAL RADIOLOGICAL DEFENSE LABORATOR
OpenNet Entry Date:
1994 Aug 26
Description/Abstract:
THE CALCULATION OF GAMMA EXPOSURE RATES FROM THE ABOVE-SURFACE URANIUM -235 FISSION-PRODUCT SOURCES RESULTING FROM UNDERWATER NUCLEAR EXPLOSI ONS CONSTITUTES A COMPLEX PROBLEM PRIMARILY BECAUSE (1) THE ENERGIES O F THE PHOTONS EMITTED FROM THE SOURCES COVER THE ENTIRE FISSION-PRODUC T SPECTRUM (WHICH VARIES WITH TIME AFTER FISSION), AND (2) THE ATTENUA TION OF THESE PHOTONS VARIES WITH THEIR ENERGY AND WITH THE DENSITY OF THE SOURCES AND SURROUNDING ATMOSPHERE. FOR CIRCUMVENTING THIS COMPUT ATIONAL COMPLEXITY, A PROCEDURE IS PRESENTED BY WHICH GAMMA EXPOSURE R ATES CAN BE CALCULATED FOR A SINGLE PRIMARY PHOTON WHOSE RATE OF ENERG Y EMISSION, AT ANY TIME AFTER FISSION, IS EQUAL TO THAT OF THE ENTIRE FISSION-PRODUCT SPECTRUM. FROM LEAST-SQUARES APPROXIMATIONS TO THE POI NT-SOURCE EQUATION FOR THE CALCULATION OF GAMMA EXPOSURE RATES, "EFFEC TIVE" ATTENUATION COEFFICIENTS ARE DERIVED FOR THIS PRIMARY PHOTON, AT SEVERAL TIMES DURING THE FIRST HALF-HOUR FOLLOWING URANIUM-235 FISSIO N, FOR A RANGE OF AIR-WATER MIXTURE DENSITIES (APPROPRIATE TO THE ABOV E-SURFACE ENVIRONMENT FOLLOWING AN UNDERWATER NUCLEAR EXPLOSION). THES E COEFFICIENTS ARE EXPRESSED AS FUNCTIONS OF THOSE DERIVED FOR AIR AT STANDARD TEMPERATURE AND PRESSURE. IN THE DERIVATION OF THESE COEFFIC IENTS, THE VARIATION OF AIR DENSITY WITH ALTITUDE IS CONSIDERED AND DI STANCE CORRECTION FACTORS ARE DEVELOPED TO ENHANCE THE GOODNESS OF THE LEAST-SQUARES FITS EMPLOYED.


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