Environmental Monitoring Report for the Nevada Test Site and Other Test Areas Used for Underground Nuclear Detonations

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BEST AVAILABLE COPY ENVIRONMENTAL MONITORING REPORT FOR THE NEVADA TEST SITE AND OTHER TEST AREAS USED FOR UNDERGROUND NUCLEAR DETONATIONS January through December 1975 Monitoring Operations Division Environmental Monitoring and Support Laboratory U.S. ENVIRONMENTAL PROTECTION AGENCY Las Vegas, Nevada 89114 This work performed under a Memorandum of U.S. ENERGY RESEARCH & DEVELOPMENT ADMINISTRATION BEST AVAILABLE COPY

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BEST AVAILABLE COPY This report was prepared as an account of work sponsored by the United States Government. Neither the United States nor the United States Energy Research and Development Administration, nor any of their employees, nor any of their contractors, subcontractors, or their employees, make any warranty, express or implied, or assume any legal liability or responsibility for the accuracy, completeness or usefulness of any information, apparatus, product or process disclosed, or represent that its use would not infringe privatelyThis document is available to the public through the National Technical Information Service, U.S. Department of Commerce, Springfield, Virginia 22161. BEST AVAILABLE COPY

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BEST AVAILABLE COPY TABLE OF CONTENTS LIST OF FIGURES vl LIST OF TABLES vii NEVADA TEST SITE 1 Geology and Hydrology 3 Land Use of NTS Environs 4 OTHER TEST SITES 6 MONITORING DATA COLLECTION, ANALYSIS, AND EVALUATION 9 AIR SURVEILLANCE NETWORK 10 NOBLE GAS AND TRITIUM SURVEILLANCE NETWORK 11 MILK SURVEILLANCE NETWORK 16 WATER SURVEILLANCE NETWORK 17 LONG-TERM HYDROLOGICAL MONITORING PROGRAM 17 Nevada Test Site 18 Other Test Sites 19 APPENDIX A. RADIATION PROTECTION STANDARDS FOR OFF-NTS 90 EXTERNAL AND INTERNAL EXPOSURE APPENDIX B. DOSE ASSESSMENT CALCULATIONS 92 APPENDIX C. LIST OF ABBREVIATIONS AND SYMBOLS 94 BEST AVAILABLE COPY

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BEST AVAILABLE COPY LIST OF FIGURES 1 Nevada Test Site Location 25 2 Nevada Test Site Road and Facility Map 26 3 Groundwater Flow Systems - Nevada Test Site 27 4 General Land Use, Nevada Test Site Vicinity 28 5 Location of Family Milk Cows and Goats 29 6 Location of Dairy Cows 30 7 Population of Arizona, California, Nevada, and Utah 31 Counties Near the Nevada Test Site 8 Air Surveillance Network 32 9 Noble Gas and Tritium Surveillance Network 33 11 Milk Surveillance Network 35 12 On-Site Long-Term Hydrological Monitoring Program, 36 Nevada Test Site 13 Off-Site Long-Term Hydrological Monitoring Program, 37 Nevada Test Site 14 Long-Term Hydrological Monitoring Locations, 38 Carlsbad, New Mexico, Project Gnome/Coach 15 Long-Term Hydrological Monitoring Locations, 39 Fallon, Nevada, Project Shoal 16 Long-Term Hydrological Monitoring Locations, 40 Salt Dome, Mississippi) 17 Long-Term Hydrological Monitoring Locations, 41 Project Dribble/Miracle Play (Tatum Salt Dome, Mississippi) 18 Long-Term Hydrological Monitoring Locations, 42 Rio Arriba County, New Mexico, Project Gasbuggy 19 Long-Term Hydrological Monitoring Locations, 43 Rulison, Colorado, Project Rulison 20 Long-Term Hydrological Monitoring Locations, 44 Central Nevada Test Area, Faultless Event BEST AVAILABLE COPY

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BEST AVAILABLE COPY The Atomic Energy Commission (AEC) used the Nevada Test Site (NTS) from January 1951 through January 19, 1975, as an area for conducting nuclear detonations, nuclear rocket-engine development, nuclear medicine studies, and miscellaneous nuclear and non-nuclear experiments. Beginning on January 19, 1975, these responsibilities were transferred to the newly-formed U.S. Energy Research and Development Administration (ERDA). Atmospheric nuclear tests were conducted periodically from 1951 through October 30, 1958, at which time a testing moratorium was Implemented. Since September 1, 1961, in accordance with the limited test ban treaty, all nuclear detonations have been conducted underground with the expectation of containment except for four slightly above ground or shallow underground tests of Operation Dominic II and five nuclear earth-cratering experiments conducted under the Plowshare program. The U.S. Public Health Service (PHS), from 1953 through 1970, and the U.S. Environmental Protection Agency (EPA), from 1970 to the present, have maintained facilities at the NTS or in Las Vegas, Nevada, for the purpose of providing an Off-Site Radiological Safety Program for the nuclear testing program. In addition, off-site surveillance has been provided by the PHS/EPA for nuclear explosive tests at places other than the NTS. Prior to 1953, the surveillance program was performed by the Los Alamos Scientific Laboratory and U.S. Army personnel. The objective of the Program since 1953 has been to measure levels and trends of radioactivity in the off-site environment surrounding testing areas to assure that the testing is in compliance with existing radiation protection standards. To assess off-site radiation levels, routine sampling networks for milk, water, and air are maintained along with a dosimetry network and special sampling of food crops, soil, etc., as required. For the purpose of implement ing protective actions, providing immediate radiation monitoring, and obtain ing environmental samples rapidly after a release of radioactivity, mobile monitoring personnel are also placed in areas downwind of NTS or other test areas prior to each test. In general, analytical results showing radioactivity levels above natu rally occurring levels have been published In reports covering a test series or test project. Beginning in 1959 for reactor tests, and in 1962 for weapons tests, surveillance data for each individual test which released radioactivity off-site were reported separately. Commencing in January 1964, and continuing through December 1970, these individual reports for nuclear tests were also summarized and reported every 6 months. The individual analytical results for all routine or special milk samples were also included in the 6-month summary In 1971, the AEC implemented a requirement (ERDA Manual, Chapter 0513) for a comprehensive radiological monitoring report from each of the several contractors or agencies involved in major nuclear activities. The compilation BEST AVAILABLE COPY

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BEST AVAILABLE COPY of these various reports since that time and their entry into the general literature serve the purpose of providing a single source of information concerning the environmental impact of nuclear activities. To provide more v rapid dissemination of data, the monthly report of analytical results of all air data collected since July 1971, and all milk and water samples collected since January 1972, were submitted to the appropriate state health depart- ^ ments involved, and were also published in Radiation Data and Reports, a monthly publication of the EPA which was discontinued at the end of 1974. Beginning with the first quarter of 1975, air and milk sample data have been reported quarterly. Dosimetry data were included beginning with the Since 1962, PHS/EPA aircraft have also been used during nuclear tests to provide rapid monitoring and sampling for releases of radioactivity. Early aircraft monitoring data obtained immediately after a test are used to posi tion mobile radiation monitoring personnel on the ground, and the results of airborne sampling are used to quantitate the inventories, diffusion, and transport of the radionuclides released. Beginning in 1971, all monitoring and sampling results by aircraft have been reported in effluent monitoring data reports in accordance with the ERDA Manual, Chapter 0513. BEST AVAILABLE COPY

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BEST AVAILABLE COPY v LIST OF TABLES 1 Characteristics of Climatic Types in Nevada 2 2 Underground Testing Conducted Off the Nevada Test Site 45 3 Summary of Analytical Procedures 47 4 1975 Summary of Analytical Results for the Noble Gas 50 and Tritium Surveillance Network 5 1975 Summary of Radiation Doses for the Dosimetry Network 53 6 1975 Summary of Analytical Results for the Milk Surveillance 56 7 Analytical Criteria for Long-Term Hydrological Monitoring 60 8 1975 Summary of Analytical Results for the Nevada Test Site 61 Monthly Long-Term Hydrological Monitoring Program ^ 9 1975 Summary of Analytical Results for the Nevada Test Site 64 10 1975 Summary of Analytical Results for the Nevada Test Site 70 11 1975 Summary of Analytical Results for the Off-NTS Long-Term 73 Hydrological Monitoring Program BEST AVAILABLE COPY

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BEST AVAILABLE COPY Under a Memorandum of Understanding, No. AT(26-l)-539, with the U.S. Energy Research and Development Administration (ERDA), the U.S. Environmental Protection Agency (EPA), Environmental Monitoring and Support Laboratory-Las Vegas (EMSL-LV), continued its Off-Site Radiological Safety Program within the environment surrounding the Nevada Test Site (NTS) and at other sites designated by the ERDA during 1975. This report, prepared in accordance with the ERDA Manual, Chapter 0513, contains summaries of EMSL-LV sampling methods, analytical procedures, and the analytical results of environmental samples collected in support of ERDA nuclear testing activities. Where applicable, sampling data are compared to appropriate guides for external and internal exposures to ionizing radiation. In addition, a brief summary of pertinent and demographical features of the NTS and the NTS environs is presented for NEVADA TEST SITE „ The major programs conducted at the NTS in the past have been nuclear weapons development, proof-testing and weapons safety, testing for peaceful uses of nuclear explosives (Project Plowshare), reactor/engine development f for nuclear rocket and ram-jet applications (Projects Pluto and Rover), basic high-energy nuclear physics research, and seismic studies (Vela-Uniform). During this report period these programs were continued with the exception of Project Pluto, discontinued in 1964, and Project Rover, which was terminated in January 1973. No Plowshare nuclear tests were conducted at the NTS or any other site during this period. All nuclear weapons tests were conducted under ground to minimize the possibility of the release of fission products to the The Nevada Test Site (Figures 1 and 2) is located in Nye County, Nevada, with its southeast corner about 90 km northwest of Las Vegas. The NTS has an area of about 3500 km2 and varies from 40-56 km in width (east-west) and from 64-88 km in length (north-south). This area consists of large basins or flats about 900-1200 m above mean sea level (MSL) surrounded by mountain ranges The NTS is nearly surrounded by an exclusion area collectively named the Nellis Air Force Range. The Range, particularly to the north and east, pro vides a buffer zone between the test areas and public lands. This buffer zone varies from 24-104 km between the test area and land that is open to the public. Depending upon wind speed and direction, this provides a delay of from 1/2 to more than 6 hours before any accidental release of airborne radioactivity could pass over public lands. BEST AVAILABLE COPY

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BEST AVAILABLE COPY The climate of the NTS and surrounding area is variable, primarily due to altitude and the rugged terrain. Generally, the climate is referred to as Continental Arid. Throughout the year there is not sufficient water to sup port tree or crop growth without irrigation. The climate may be classified by the types of vegetation which grow under these conditions. According to Houghton et al., this method, developed by KBppen in 1918, recognizes five basic climatic conditions as humid tropical, dry, humid mesothermal, humid microthermal, and polar (five-sixths of Nevada falls in the dry category). KBppen's classification of dry conditions is fur ther subdivided on the basis of temperature and severity of drought. Table 1, from Houghton et al., summarizes the different characteristics of these cli matic types in Nevada. TABLE 1. CHARACTERISTICS OF CLIMATIC TYPES IN NEVADA Type Winter Summer *Limits of annual precipitation overlap because of variations in temperature which affect the water balance. As pointed out by Houghton et al., 90 percent of Nevada's population lives in areas with less than 25 cm of rain per year or in areas which would be classified as mid-latitude steppe to low-latitude desert regions. BEST AVAILABLE COPY

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BEST AVAILABLE COPY According to Quiring, 1968, the NTS average annual precipitation ranges from about 10 cm at the 900-m altitude to around 25 cm on the plateaus. During the winter months, the plateaus may be snow-covered for periods of several days or weeks. Snow is uncommon on the flats. Temperatures vary considerably with elevation, slope, and local air currents. The average daily high (low) temperatures at the lower altitudes are around 10° (-4°) C in January and 35° have been observed at the NTS. The direction from which winds blow, as measured on a 30-m tower at the Yucca observation station, is predominantly northerly except for the months of May through August when winds from the south-southwest predominate. Be cause of the prevalent mountain/valley winds in the basins, south to south west winds predominate during daylight hours during most months. During the winter months southerly winds have only a slight edge over northerly winds for a few hours during the warmest part of the day. These wind patterns may be quite different at other locations on the NTS because of local terrain effects and differences in elevation (Quiring, 1968), Geology and Hydrology Geological and hydrological studies of the NTS have been in progress by the U.S. Geological Survey and various other institutions since 1956. Be cause of this continuing effort, including subsurface studies of numerous bore holes, the surface and underground geological and hydrological characteristics for much of the NTS are known in considerable detail. This is particularly true for those areas in which underground experiments are conducted. A com prehensive summary of the geology and hydrology of the NTS was published in 1968 as Memoir 110 by the Geological Society of America, entitled "Nevada Test There are two major hydrologic systems on the NTS (Figure 3). Groundwater in the northwestern part of NTS or in the Pahute Mesa has been reported (WASH-DRAFT, 1975) to travel somewhere between 2 and 80 m per year to the south and southwest toward the Ash Meadows discharge area in the Amargosa Desert. It is estimated that the groundwater to the east of the NTS moves from north to south at a rate not less than 2 nor greater than 220 m per year. Carbon14 analyses of this eastern groundwater indicate that the lower velocity is nearer the true value. At Mercury Valley, in the extreme southern part of the NTS, the groundwater flow direction shifts to the southwest toward the Ash Meadows discharge area in the southeastern Amargosa Valley. Depths of water on the NTS vary from about 100 m beneath the valleys in the southeastern part of the site to more than 600 m beneath …

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