Subfile: ERA (Energy Research Abstracts). Country of Origin: United States Abstract: Several inherent problems in the methodology employed in the ground water resource study of Tarawa Atoll (Lloyd, et al., 1981) are described. Studies of Enewetak Atoll have provided data that require a Significantly different conceptual model of the atoll hydrogeology system. Comparison of well, lagoon, and ocean tidal observations with a mathematical model that assumes horizontal tidal propagation indicates that the observed results are more consistent with a system that is controlled by vertical coupling between the unconsolidated surface aquifer and an underlying aquifer of more permeable limestone. This indicates that most fresh water recharged to the aquifer migrates downward and mixes with the sea water in a deeper aquifer providing easy exchange with the ocean. Lloyd, et al., do not take tidal mixing or vertical transport into account and it therefore seems likely that fresh water inventories are significantly overestimated. Failure to include these significant loss terms in the island water budget may also account for calculated heads above ground level. (OMT) ; Major Descriptors: *ENIWETOK -- GEOLOGY; *ENIWETOK -- HYDROLOGY; *GROUND WATER -- MATHEMATICAL MODELS Descriptors: AQUIFERS; MIXING; SEAWATER Broader Terms: HYDROGEN COMPOUNDS; ISLANDS; OCEANIA; OXYGEN COMPOUNDS; WATER Subject Categories: (-1989) 10/5/716 520100* MARSHALL ISLANDS; MICRONESIA; -- Environment, Aquatic -- Basic Studies -- (Item 416 from file: 103) 01108312 EDB-83-008313 Title: beta- and gamma-Comparative dose estimates on Eniwetok Atoll Author(s): Crase, Affiliation: Source: K.W.; Gudiksen, P.H.; Robison, W.L. Lawrence Livermore National Laboratory, Health Phys. (United Kingdom) v 42:5. CA Coden: HLTPA Publication Date: May 1982 p 559-564 Document Type: Journal Article Language: English Journal Announcement: EDB8210 Country of Origin: United States Abstract: Eniwetok Atoll is one of the Pacific atolls used for atmospheric testing of U.S. nuclear weapons. Beta dose and gamma-ray exposure measurements were made on two islands of the Eniwetok Atoll during July-August 1976 to determine the beta and low energy gamma-contribution to the total external radiation doses to the returning Marshallese. Measurements were made at numerous locations with thermoluminescent dosimeters (TLD), pressurized ionization chambers, portable Nal detectors, and thin-window pancake GM probes. Results of the TLD measurements with and without a beta-attenuator indicate that approx. 29% of the total dose rate at 1m in air is due to beta- or low energy gamma-contribution. The contribution at any particular site, however, is somewhat dependent on ground cover, since a Minimal amount of vegetation will reduce it significantly from that over bare soil, but thick stands of vegetation have little effect on any further reductions. Integral 30-yr external shallow dose estimates for future inhabitants were made and compared with external dose estimates of a previous large scale radiological survey (En73). Integral 30-yr shallow external dose estimates are 25-50% higher than whole body estimates. Due to the low penetrating ability of the beta’s or low energy gamma’s, however, several remedial actions can be taken to reduce the shallow dose contribution to the total external dose.; on ~ Major Descriptors: *RADIATION DOSES -- RADIOECOLOGICAL CONCENTRATION c Descriptors: BETA DETECTION; COMPARATIVE EVALUATIONS; ENIWETOK; EXTERNAL mo IRRADIATION; FORECASTING; GAMMA DETECTION; HUMAN POPULATIONS; MEASURING~ METHODS; NUCLEAR EXPLOSIONS; PLANTS; STATISTICS; THERMOLUMINESCENT DOSEMETERS; THERMOLUMINESCENT DOSIMETRY Broader Terms: CHARGED PARTICLE DETECTION; DETECTION; DOSEMETERS; DOSES; DOSIMETRY; ECOLOGICAL CONCENTRATION; EXPLOSIONS; IRRADIATION; ISLANDS; LUMINESCENT DOSEMETERS; MARSHALL ISLANDS; MATHEMATICS; MEASURING