Cesium-137 inventories in undisturbed soils at over 150 sites throughout Utah have been estimated... more Cesium-137 inventories in undisturbed soils at over 150 sites throughout Utah have been estimated from in situ gamma-ray spectra and analyses of soil samples obtained in June 1979. It appears, based on a preliminary analysis, that the maximum /sup 137/Cs fallout on southwestern Utah from nuclear weapons tests carried out at the Nevada Test Site was about 50 mCi/km/sup 2/. It is estimated that this level of activity would have generated a cumulative free air dose from all fission products of less than 5 rad, which is in reasonable agreement with the value inferred from the radiation surveys conducted after each of the Nevada tests. This suggests that the residents of southwestern Utah were not exposed to external radiation from the Nevada tests significantly greater than had previously been reported. Planned mass isotopic analyses of the plutonium present in the soil samples should permit a more precise estimate of the external radiation doses delivered at each site.
Advertisement. Close Window. Close Window. Thank you for choosing to subscribe to the eTOC for He... more Advertisement. Close Window. Close Window. Thank you for choosing to subscribe to the eTOC for Health Physics. Enter your Email address: Wolters Kluwer Health may email you for journal alerts and information, but is committed ...
This report was prepared as an account of Government sponsored work. Neither the United States, n... more This report was prepared as an account of Government sponsored work. Neither the United States, nor the Commission, nor any person acting on behalf of the Commission: A. Makes any warranty or representation, expressed or implied, with respect to the accu racy, completeness, or usefulness of the information contained in this report, or that the use of any information, apparatus, method, or process disclosed in this report may not infringe privately owned rights; or B. Assumes any liabilities with respect to the use of, or for damages resulting from the use of any information, apparatus, method, or process disclosed in this report. As used In the above, "person acting on behalf of the Commission" includes any em ployee or contractor of the Commission, or employee of such contractor, to the extent that such employee or contractor of the Commission, or employee of such contractor prepares, disseminates, or provides access to, any information pursuant to his employment or contract with the Commission, or his employment with such contractor. This report has been reproduced directly from the best available copy.
This report provides estimates of the external radiation exposure and whole-body effective dose r... more This report provides estimates of the external radiation exposure and whole-body effective dose received by residents of the continental U.S. during the period 1951-1962 from weapons tests carried out at the Nevada Test Site (NTS). Estimates are given on a county-by-county basis for each test and for each year of testing. The average committed population dose from all NTS tests was about 0.5 mSv, about equivalent to 1-2 years of external radiation exposure from natural background. Residents of the counties immediately downwind from the NTS incurred much higher doses, in excess of 3 mSv, while the residents of the Far West, Pacific Northwest and Southeast received lower than average exposures. The tests and radionuclides that contributed the most exposure are discussed, as well as the dependence on fallout time of arrival. The most exposed individuals were outdoor workers; the least exposed were persons who spent most of their time indoors in heavily constructed buildings. The deposition of radionuclides that contribute to internal radiation exposure via the ingestion pathway was also calculated on a county-by-county and test-by-test basis. The general pattern of deposition, tests contributing the most to the deposition, deposition density versus distance from the NTS, and the differences in deposition between radionuclides are discussed. In general the deposition of long-lived radionuclides such as Sr-90 and Cs-137 was about a factor of 20 less than that from "global fallout" from highyield weapons tests carried out in the Pacific and Soviet Union. However, the deposition of short-lived isotopes such as I-131 was greater than from "global fallout."
Estimates of exposure rates and fallout-arrival times have been made for each of 142 counties or ... more Estimates of exposure rates and fallout-arrival times have been made for each of 142 counties or county segments for 55 nuclear events producing significant deposition downwind from the Nevada Test Site. All sources of available data were examined to provide the best possible estimates for each event. The cumulative fallout deposited per unit area in each county based on these estimates is compared with estimates of cumulative deposition density based on analyses of contemporary and historical soil samples. The good agreement between the two sets of cumulative deposition estimates gives credence to the individual event estimates and suggests that no major sources of fission-product deposition were overlooked. This county database is being used as primary input data in a number of on-going dose-reconstruction studies.
From the analyses of the /sup 137/Cs and /sup 239 +240/Pu content and from the plutonium mass iso... more From the analyses of the /sup 137/Cs and /sup 239 +240/Pu content and from the plutonium mass isotopic composition of soil samples recovered in Utah, the fraction of these radionuclides that were deposited in Utah by global and by Nevada Test Site (NTS) fallout was determined. Deposition of NTS /sup 137/Cs and /sup 239 +240/Pu followed similar patterns with elevated values existing in the southwestern corner of Utah around St. George, and then decreasing rapidly with distance along a northeasterly direction from NTS. Then midway along this diagonal through Utah, NTS fallout of these radionuclides increased again and remained elevated throughout the remainder of the state. In the populated Provo and Salt Lake City valleys, the NTS /sup 137/Cs deposits were about 1/2 that of St. George and the NTS /sup 239 +240/Pu deposits were even greater than at St. George.
A letter to the editor comments on a recent Health Physics article in which dose-rate conversion ... more A letter to the editor comments on a recent Health Physics article in which dose-rate conversion factors were presented for external exposure to monoenergetic photon emitters in soil for various source depth distributions. The buildup factors are discussed.
We at the Environmental Measurements Laboratory (EML) have been measuring anthropogenic radionucl... more We at the Environmental Measurements Laboratory (EML) have been measuring anthropogenic radionuclides released into the atmosphere using our Global Monitoring Programs since the early 1960s. EML's Global Monitoring Programs consist of 78 fallout sites and 36 surface air sampling sites (see Fig. 1), representing the most extensive and comprehensive network of its kind in the world (Larsen et al., 1989; Larsen & Sanderson). On April 6, 1993, an accident at a reprocessing plant in the Tomsk-7 military nuclear complex located 16 km north of the Siberian city of Tomsk, Russia, released radioactive materials into the environment. The
Mean hourly ground-level /sup 85/Kr concentrations measured at six locations within 10 km of the ... more Mean hourly ground-level /sup 85/Kr concentrations measured at six locations within 10 km of the Savannah River Plant chemical separations facilities during calendar year 1976 are presented in tabular form along with the mean daily concentrations for each site. These data, obtained with arrays of thin window G-M counters especially designed for this purpose, can be used to test point source atmospheric dispersion models.
A high-pressure ion chamber filled with 2.5825 X lo5 kg m-' argon was used to measure the dose ra... more A high-pressure ion chamber filled with 2.5825 X lo5 kg m-' argon was used to measure the dose rates of several sites of interest in an attempt to evaluate the dose rates contributed by cosmic rays. Observation sites included two water reservoirs deeper than 110 m, Mount Ali which is higher than 2500 m, airliners flying at altitudes higher than 6700 m, and some sites at sea level. The results of this investigation were compared with those reported by the United Nations Scientific Committee on the Effects of Atomic Radiation and used for the determination of background radiation monitored with thermoluminescent dosimeters and sodium iodide detectors.
The rapid change in energy deposition and particle flux which occurs when a 1 GeV electron-initia... more The rapid change in energy deposition and particle flux which occurs when a 1 GeV electron-initiated shower developing in lead or iron crosses over into a water medium was studied using a recently developed Monte Carto code. Agreement with experimental data is quite good. Similer calculations were done for 200 MeV, 500 MeV, and 1 GeV electron-initiated air showers entering iron and aluminum. The calculations indicate that significant changes in energy deposition and flux occur over quite small distances from the boundary. For instance, the transition effect will produce an enhancement of about 20% in the measured gas ionization due to the electromagnetic component of the cosmic radiation when using 3 g/cm 2 thick steel-walled ionization chambers. The magnitude of the Monte Carlo calculated transition effects are smaller, however, than predicted in earlier studies which relied on approximation B of shower theory.
The new interest in determining small changes in environmental radiation levels as evidenced by t... more The new interest in determining small changes in environmental radiation levels as evidenced by the establishment of as low as practicable numerical criteria indicates a need for reliable low-level radiation measurements. Though the expected contributions from routine operation of nuclear facilities are small compared to existing contributions to dose from natural radioactivity, cosmic radiation and fallout, monitoring programs should be modified to document actual levels and improve public relations as originally suggested by the ICRP. The relative value of instantaneous environmental exposure rate measurements and continuous monitoring is described. Model experiments, some by the Health and Safety Laboratory, are being performed to establish the ranges of validity of dose assessment calculations and improve monitoring techniques. The importance of studies of background variations, trends in long-term additions to the environment, and pathway-to-man analyses is described.
Cesium-137 inventories in undisturbed soils at over 150 sites throughout Utah have been estimated... more Cesium-137 inventories in undisturbed soils at over 150 sites throughout Utah have been estimated from in situ gamma-ray spectra and analyses of soil samples obtained in June 1979. It appears, based on a preliminary analysis, that the maximum /sup 137/Cs fallout on southwestern Utah from nuclear weapons tests carried out at the Nevada Test Site was about 50 mCi/km/sup 2/. It is estimated that this level of activity would have generated a cumulative free air dose from all fission products of less than 5 rad, which is in reasonable agreement with the value inferred from the radiation surveys conducted after each of the Nevada tests. This suggests that the residents of southwestern Utah were not exposed to external radiation from the Nevada tests significantly greater than had previously been reported. Planned mass isotopic analyses of the plutonium present in the soil samples should permit a more precise estimate of the external radiation doses delivered at each site.
Advertisement. Close Window. Close Window. Thank you for choosing to subscribe to the eTOC for He... more Advertisement. Close Window. Close Window. Thank you for choosing to subscribe to the eTOC for Health Physics. Enter your Email address: Wolters Kluwer Health may email you for journal alerts and information, but is committed ...
This report was prepared as an account of Government sponsored work. Neither the United States, n... more This report was prepared as an account of Government sponsored work. Neither the United States, nor the Commission, nor any person acting on behalf of the Commission: A. Makes any warranty or representation, expressed or implied, with respect to the accu racy, completeness, or usefulness of the information contained in this report, or that the use of any information, apparatus, method, or process disclosed in this report may not infringe privately owned rights; or B. Assumes any liabilities with respect to the use of, or for damages resulting from the use of any information, apparatus, method, or process disclosed in this report. As used In the above, "person acting on behalf of the Commission" includes any em ployee or contractor of the Commission, or employee of such contractor, to the extent that such employee or contractor of the Commission, or employee of such contractor prepares, disseminates, or provides access to, any information pursuant to his employment or contract with the Commission, or his employment with such contractor. This report has been reproduced directly from the best available copy.
This report provides estimates of the external radiation exposure and whole-body effective dose r... more This report provides estimates of the external radiation exposure and whole-body effective dose received by residents of the continental U.S. during the period 1951-1962 from weapons tests carried out at the Nevada Test Site (NTS). Estimates are given on a county-by-county basis for each test and for each year of testing. The average committed population dose from all NTS tests was about 0.5 mSv, about equivalent to 1-2 years of external radiation exposure from natural background. Residents of the counties immediately downwind from the NTS incurred much higher doses, in excess of 3 mSv, while the residents of the Far West, Pacific Northwest and Southeast received lower than average exposures. The tests and radionuclides that contributed the most exposure are discussed, as well as the dependence on fallout time of arrival. The most exposed individuals were outdoor workers; the least exposed were persons who spent most of their time indoors in heavily constructed buildings. The deposition of radionuclides that contribute to internal radiation exposure via the ingestion pathway was also calculated on a county-by-county and test-by-test basis. The general pattern of deposition, tests contributing the most to the deposition, deposition density versus distance from the NTS, and the differences in deposition between radionuclides are discussed. In general the deposition of long-lived radionuclides such as Sr-90 and Cs-137 was about a factor of 20 less than that from "global fallout" from highyield weapons tests carried out in the Pacific and Soviet Union. However, the deposition of short-lived isotopes such as I-131 was greater than from "global fallout."
Estimates of exposure rates and fallout-arrival times have been made for each of 142 counties or ... more Estimates of exposure rates and fallout-arrival times have been made for each of 142 counties or county segments for 55 nuclear events producing significant deposition downwind from the Nevada Test Site. All sources of available data were examined to provide the best possible estimates for each event. The cumulative fallout deposited per unit area in each county based on these estimates is compared with estimates of cumulative deposition density based on analyses of contemporary and historical soil samples. The good agreement between the two sets of cumulative deposition estimates gives credence to the individual event estimates and suggests that no major sources of fission-product deposition were overlooked. This county database is being used as primary input data in a number of on-going dose-reconstruction studies.
From the analyses of the /sup 137/Cs and /sup 239 +240/Pu content and from the plutonium mass iso... more From the analyses of the /sup 137/Cs and /sup 239 +240/Pu content and from the plutonium mass isotopic composition of soil samples recovered in Utah, the fraction of these radionuclides that were deposited in Utah by global and by Nevada Test Site (NTS) fallout was determined. Deposition of NTS /sup 137/Cs and /sup 239 +240/Pu followed similar patterns with elevated values existing in the southwestern corner of Utah around St. George, and then decreasing rapidly with distance along a northeasterly direction from NTS. Then midway along this diagonal through Utah, NTS fallout of these radionuclides increased again and remained elevated throughout the remainder of the state. In the populated Provo and Salt Lake City valleys, the NTS /sup 137/Cs deposits were about 1/2 that of St. George and the NTS /sup 239 +240/Pu deposits were even greater than at St. George.
A letter to the editor comments on a recent Health Physics article in which dose-rate conversion ... more A letter to the editor comments on a recent Health Physics article in which dose-rate conversion factors were presented for external exposure to monoenergetic photon emitters in soil for various source depth distributions. The buildup factors are discussed.
We at the Environmental Measurements Laboratory (EML) have been measuring anthropogenic radionucl... more We at the Environmental Measurements Laboratory (EML) have been measuring anthropogenic radionuclides released into the atmosphere using our Global Monitoring Programs since the early 1960s. EML's Global Monitoring Programs consist of 78 fallout sites and 36 surface air sampling sites (see Fig. 1), representing the most extensive and comprehensive network of its kind in the world (Larsen et al., 1989; Larsen & Sanderson). On April 6, 1993, an accident at a reprocessing plant in the Tomsk-7 military nuclear complex located 16 km north of the Siberian city of Tomsk, Russia, released radioactive materials into the environment. The
Mean hourly ground-level /sup 85/Kr concentrations measured at six locations within 10 km of the ... more Mean hourly ground-level /sup 85/Kr concentrations measured at six locations within 10 km of the Savannah River Plant chemical separations facilities during calendar year 1976 are presented in tabular form along with the mean daily concentrations for each site. These data, obtained with arrays of thin window G-M counters especially designed for this purpose, can be used to test point source atmospheric dispersion models.
A high-pressure ion chamber filled with 2.5825 X lo5 kg m-' argon was used to measure the dose ra... more A high-pressure ion chamber filled with 2.5825 X lo5 kg m-' argon was used to measure the dose rates of several sites of interest in an attempt to evaluate the dose rates contributed by cosmic rays. Observation sites included two water reservoirs deeper than 110 m, Mount Ali which is higher than 2500 m, airliners flying at altitudes higher than 6700 m, and some sites at sea level. The results of this investigation were compared with those reported by the United Nations Scientific Committee on the Effects of Atomic Radiation and used for the determination of background radiation monitored with thermoluminescent dosimeters and sodium iodide detectors.
The rapid change in energy deposition and particle flux which occurs when a 1 GeV electron-initia... more The rapid change in energy deposition and particle flux which occurs when a 1 GeV electron-initiated shower developing in lead or iron crosses over into a water medium was studied using a recently developed Monte Carto code. Agreement with experimental data is quite good. Similer calculations were done for 200 MeV, 500 MeV, and 1 GeV electron-initiated air showers entering iron and aluminum. The calculations indicate that significant changes in energy deposition and flux occur over quite small distances from the boundary. For instance, the transition effect will produce an enhancement of about 20% in the measured gas ionization due to the electromagnetic component of the cosmic radiation when using 3 g/cm 2 thick steel-walled ionization chambers. The magnitude of the Monte Carlo calculated transition effects are smaller, however, than predicted in earlier studies which relied on approximation B of shower theory.
The new interest in determining small changes in environmental radiation levels as evidenced by t... more The new interest in determining small changes in environmental radiation levels as evidenced by the establishment of as low as practicable numerical criteria indicates a need for reliable low-level radiation measurements. Though the expected contributions from routine operation of nuclear facilities are small compared to existing contributions to dose from natural radioactivity, cosmic radiation and fallout, monitoring programs should be modified to document actual levels and improve public relations as originally suggested by the ICRP. The relative value of instantaneous environmental exposure rate measurements and continuous monitoring is described. Model experiments, some by the Health and Safety Laboratory, are being performed to establish the ranges of validity of dose assessment calculations and improve monitoring techniques. The importance of studies of background variations, trends in long-term additions to the environment, and pathway-to-man analyses is described.
Uploads
Papers by Harold Beck