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Title: Physical response of backfill materials to mineralogical changes in a basalt environment. [Sand-clay mixture containing 25% bentonite]

Abstract

Backfill materials surrounding waste canisters in a high-level nuclear waste repository are capable of ensuring very slow flow of groundwater past the canisters, and thereby increase the safety of the repository. However, in the design of a repository it will be necessary to allow for possible changes in the backfill. In this experimental program, changes in permeability, swelling behavior, and plastic behavior of the backfill at the temperatures, pressures, and radiation levels expected in a repository are investigated. The emphasis is on investigation of relevant phenomena and evaluation of experimental procedures for use in licensing procedures. The permeability of a slightly compacted sand-clay mixture containing 25% bentonite, with a dry bulk density of 1.59 g/cm/sup 3/, was determined to be 0.9 x 10/sup -18/ m/sup 2/ in liquid water at 25 and 200/sup 0/C, respectively. This is sufficiently low to demonstrate the potential effectiveness of proposed materials. In practice, fractures in the host rock may form short circuits around the backfill, so an even lower flow rate is probable. However, alteration by any of several mechanisms is expected to change the properties of the backfill. Crushed basalt plus bentonite is a leading candidate backfill for a basalt repository. Experiments showmore » that basalt reacts with groundwater vapor or with liquid groundwater producing smectites, zeolites, silica, and other products that may be either beneficial or detrimental to the long-term performance of the backfill. Concentration of groundwater salts in the backfill by evaporation would cause immediate, but possibly reversible, reduction of the swelling abaility of bentonite. Moreover, under some circumstances, gamma radiolysis of moist air in the backfill could produce up to 0.5 mole of nitric acid or ammonia per liter of pore space. 27 references, 7 figures, 4 tables.« less

Authors:
;
Publication Date:
Research Org.:
Argonne National Lab., IL (USA)
OSTI Identifier:
5231180
Report Number(s):
CONF-8308126-5
ON: DE84009204
DOE Contract Number:  
W-31109-ENG-38
Resource Type:
Conference
Resource Relation:
Conference: NRC research annual review meeting of nuclear waste management research on geochemistry of HLW disposal, Reston, VA, USA, 30 Aug 1983
Country of Publication:
United States
Language:
English
Subject:
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; BACKFILLING; BULK DENSITY; PERMEABILITY; SAND; BASALT; HYDROTHERMAL ALTERATION; RADIOACTIVE WASTE DISPOSAL; ENGINEERED SAFETY SYSTEMS; HIGH-LEVEL RADIOACTIVE WASTES; BENTONITE; CLAYS; EXPERIMENTAL DATA; GEOLOGIC DEPOSITS; GROUND WATER; HIGH TEMPERATURE; MEDIUM TEMPERATURE; RADIOACTIVE WASTE FACILITIES; ROCK-FLUID INTERACTIONS; SWELLING; UNDERGROUND DISPOSAL; DATA; DENSITY; HYDROGEN COMPOUNDS; IGNEOUS ROCKS; INFORMATION; MANAGEMENT; MATERIALS; NUCLEAR FACILITIES; NUMERICAL DATA; OXYGEN COMPOUNDS; PHYSICAL PROPERTIES; RADIOACTIVE MATERIALS; RADIOACTIVE WASTES; ROCKS; VOLCANIC ROCKS; WASTE DISPOSAL; WASTE MANAGEMENT; WASTES; WATER; 052002* - Nuclear Fuels- Waste Disposal & Storage

Citation Formats

Couture, R A, and Seitz, M G. Physical response of backfill materials to mineralogical changes in a basalt environment. [Sand-clay mixture containing 25% bentonite]. United States: N. p., 1983. Web.
Couture, R A, & Seitz, M G. Physical response of backfill materials to mineralogical changes in a basalt environment. [Sand-clay mixture containing 25% bentonite]. United States.
Couture, R A, and Seitz, M G. Sat . "Physical response of backfill materials to mineralogical changes in a basalt environment. [Sand-clay mixture containing 25% bentonite]". United States. https://www.osti.gov/servlets/purl/5231180.
@article{osti_5231180,
title = {Physical response of backfill materials to mineralogical changes in a basalt environment. [Sand-clay mixture containing 25% bentonite]},
author = {Couture, R A and Seitz, M G},
abstractNote = {Backfill materials surrounding waste canisters in a high-level nuclear waste repository are capable of ensuring very slow flow of groundwater past the canisters, and thereby increase the safety of the repository. However, in the design of a repository it will be necessary to allow for possible changes in the backfill. In this experimental program, changes in permeability, swelling behavior, and plastic behavior of the backfill at the temperatures, pressures, and radiation levels expected in a repository are investigated. The emphasis is on investigation of relevant phenomena and evaluation of experimental procedures for use in licensing procedures. The permeability of a slightly compacted sand-clay mixture containing 25% bentonite, with a dry bulk density of 1.59 g/cm/sup 3/, was determined to be 0.9 x 10/sup -18/ m/sup 2/ in liquid water at 25 and 200/sup 0/C, respectively. This is sufficiently low to demonstrate the potential effectiveness of proposed materials. In practice, fractures in the host rock may form short circuits around the backfill, so an even lower flow rate is probable. However, alteration by any of several mechanisms is expected to change the properties of the backfill. Crushed basalt plus bentonite is a leading candidate backfill for a basalt repository. Experiments show that basalt reacts with groundwater vapor or with liquid groundwater producing smectites, zeolites, silica, and other products that may be either beneficial or detrimental to the long-term performance of the backfill. Concentration of groundwater salts in the backfill by evaporation would cause immediate, but possibly reversible, reduction of the swelling abaility of bentonite. Moreover, under some circumstances, gamma radiolysis of moist air in the backfill could produce up to 0.5 mole of nitric acid or ammonia per liter of pore space. 27 references, 7 figures, 4 tables.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1983},
month = {1}
}

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