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Title: Contact zones and hydrothermal systems as analogues to repository conditions

Radioactive waste isolation efforts in the US are currently focused on examining basalt, tuff, salt, and crystalline rock as candidate rock types to encompass waste repositories. As analogues to near-field conditions, the distributions of radio- and trace-elements have been examined across contacts between these rocks and dikes and stocks that have intruded them. The intensive study of the Stripa quartz monzonite has also offered the opportunity to observe the distribution of uranium and its daughters in groundwater and its relationship to U associated with fracture-filling and alteration minerals. Investigations of intrusive contact zones to date have included (1) a tertiary stock into Precambrian gneiss, (2) a stock into ash flow tuff, (3) a rhyodacite dike into Columbia River basalt, and (4) a kimberlite dike into salt. With respect to temperature and pressure, these contact zones may be considered "worst-case scenario" analogues. Results indicate that there has been no appreciable migration of radioelements from the more radioactive intrusives into the less radioactive country rocks, either in response to the intrusions or in the fracture-controlled hydrological systems that developed following emplacement. In many cases, the radioelements are locked up in accessory minerals, suggesting that artificial analogues to these would make ideal wastemore » forms. Emphasis should now shift to examination of active hydrothermal systems, studying the distribution of key elements in water, fractures, and alteration minerals under pressure and temperature conditions most similar to those expected in the near-field environment of a repository. 14 refs.« less
Authors:
;
Publication Date:
OSTI Identifier:
60580
Report Number(s):
LBL-18587; CONF-8410311-1
ON: DE85016555
DOE Contract Number:
AC03-76SF00098
Resource Type:
Conference
Resource Relation:
Conference: Workshop on radionuclide migration, Chicago, IL (United States), 1-3 Oct 1984; Other Information: PBD: Oct 1984
Research Org:
Lawrence Berkeley Lab., CA (United States)
Country of Publication:
United States
Language:
English
Subject:
05 NUCLEAR FUELS; 54 ENVIRONMENTAL SCIENCES; RADIOACTIVE WASTE DISPOSAL; RADIONUCLIDE MIGRATION; BASALT; TUFF; SALT DEPOSITS; GROUND WATER; URANIUM; DAUGHTER PRODUCTS; QUARTZ; THORIUM; Yucca Mountain Project