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Title: The occurrence and distribution of erionite at Yucca Mountain, Nevada

Abstract

We have conducted an investigation to determine the occurrence and distribution of erionite, a potential carcinogen, at Yucca Mountain, Nevada. Using x-ray powder diffraction techniques yielding detection limits to below 0.05 wt %, we positively identified erionite in only 3 out of 76 bulk and 12 fracture samples investigated. The three erionite-bearing samples (J12-620/630, UE-25aNo.1-1296.2, and USW G4-1314) all occur above the static water level in clay/zeolite-rich horizons near the top of vitrophyres. Erionite occurs as trace amounts of less than 1 wt % in the whole rock, although it may occur locally in significant amounts as fracture fillings (e.g., UE-25aNo.1-1296.2 where it comprises approximately 45 wt % of the fracture filling material). All three occurrences appear to be extremely isolated cases since erionite was not detected in neighboring samples. Erionite at Yucca Mountain apparently formed only in localized microenvironments, possibly restricted to fractures. Since erionite occurs in trace amounts only in extremely isolated instances, it should pose little or no health hazard to workers in the potential repository at Yucca Mountain or to the public. The amounts of erionite liberated to the biosphere should be negligible, particularly when compared with the amounts of erionite occurring naturally at the surfacemore » in Nevada and surrounding states. 24 refs., 7 figs., 2 tabs.« less

Authors:
;
Publication Date:
Research Org.:
Los Alamos National Lab., NM (United States)
OSTI Identifier:
137523
Report Number(s):
LA-11663-MS
ON: DE89017905; TRN: 89:025898
DOE Contract Number:
W-7405-ENG-36
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: Sep 1989
Country of Publication:
United States
Language:
English
Subject:
05 NUCLEAR FUELS; HIGH-LEVEL RADIOACTIVE WASTES; UNDERGROUND DISPOSAL; ZEOLITES; HEALTH HAZARDS; RADIOACTIVE WASTE MANAGEMENT; YUCCA MOUNTAIN; SITE CHARACTERIZATION; CARCINOGENS; SAMPLING; EVALUATION; BIOLOGICAL EFFECTS; Yucca Mountain Project

Citation Formats

Chipera, S.J., and Bish, D.L.. The occurrence and distribution of erionite at Yucca Mountain, Nevada. United States: N. p., 1989. Web. doi:10.2172/137523.
Chipera, S.J., & Bish, D.L.. The occurrence and distribution of erionite at Yucca Mountain, Nevada. United States. doi:10.2172/137523.
Chipera, S.J., and Bish, D.L.. Fri . "The occurrence and distribution of erionite at Yucca Mountain, Nevada". United States. doi:10.2172/137523. https://www.osti.gov/servlets/purl/137523.
@article{osti_137523,
title = {The occurrence and distribution of erionite at Yucca Mountain, Nevada},
author = {Chipera, S.J. and Bish, D.L.},
abstractNote = {We have conducted an investigation to determine the occurrence and distribution of erionite, a potential carcinogen, at Yucca Mountain, Nevada. Using x-ray powder diffraction techniques yielding detection limits to below 0.05 wt %, we positively identified erionite in only 3 out of 76 bulk and 12 fracture samples investigated. The three erionite-bearing samples (J12-620/630, UE-25aNo.1-1296.2, and USW G4-1314) all occur above the static water level in clay/zeolite-rich horizons near the top of vitrophyres. Erionite occurs as trace amounts of less than 1 wt % in the whole rock, although it may occur locally in significant amounts as fracture fillings (e.g., UE-25aNo.1-1296.2 where it comprises approximately 45 wt % of the fracture filling material). All three occurrences appear to be extremely isolated cases since erionite was not detected in neighboring samples. Erionite at Yucca Mountain apparently formed only in localized microenvironments, possibly restricted to fractures. Since erionite occurs in trace amounts only in extremely isolated instances, it should pose little or no health hazard to workers in the potential repository at Yucca Mountain or to the public. The amounts of erionite liberated to the biosphere should be negligible, particularly when compared with the amounts of erionite occurring naturally at the surface in Nevada and surrounding states. 24 refs., 7 figs., 2 tabs.},
doi = {10.2172/137523},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Fri Sep 01 00:00:00 EDT 1989},
month = {Fri Sep 01 00:00:00 EDT 1989}
}

Technical Report:

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  • The naturally-occurring zeolite mineral erionite has a fibrous morphology and is a known human carcinogen (inhalation hazard). Erionite has been found typically in very small quantities and restricted occurrences in the course of mineralogic characterization of Yucca Mountain as a host for a high-level nuclear waste repository. The first identification of erionite was made in 1984 on the basis of morphology and chemical composition and later confirmed by X-ray diffraction analysis. It was found in the lower vitrophyre (Tptpv3) of the Topopah Spring Tuff in a borehole sidewall sample. Most erionite occurrences identified at Yucca Mountain are in the Topopahmore » Spring Tuff, within an irregular zone of transition between the lower boundary of devitrified tuff and underlying glassy tuff. This zone is fractured and contains intermingled devitrified and vitric tuff. In 1997, a second host of erionite mineralization was identified in the Exploratory Studies Facility within and adjacent to a high-angle fracture/breccia zone transgressing the boundary between the lowermost devitrified tuff (Tpcplnc) and underlying moderately welded vitric tuff (Tpcpv2) of the Tiva Canyon Tuff. The devitrified-vitric transition zones where erionite is found tend to have complex secondary-mineral assemblages, some of very localized occurrence. Secondary minerals in addition to erionite may include smectite, heulandite-clinoptilolite, chabazite, opal-A, opal-CT, cristobalite, quartz, kenyaite, and moganite. Incipient devitrification within the Topopah Spring Tuff transition zone includes patches that are highly enriched in potassium feldspar relative to the precursor volcanic glass. Geochemical conditions during glass alteration may have led to local evolution of potassium-rich fluids. Thermodynamic modeling of zeolite stability shows that erionite and chabazite stability fields occur only at aqueous K concentrations much higher than in present Yucca Mountain waters. The association of erionite with opal-A, opal-CT, and moganite suggests that erionite formed at a high silica activity.« less
  • A study of more than 22,000 feet of core from five deep drill holes at Yucca Mountain, Nevada, provided data on the attitude and vertical distribution of faults and fractures, the sense of fault displacement, and the occurrence of calcite. The study was done mainly to look for evidence of fault flattening at depth, but no consistent downward decrease in dip of faults was found, and no increase in strata rotation was evident with increasing depth. In the two drill holes located near prominent faults that dip toward the holes (USW G-3 and G-2), an apparent increase in the frequencymore » of faults occurs below the tuffs and lavas of Calico Hills. Some of this increase occurs in brittle lavas and flow breccias in the lower part of the volcanic section. In the two holes presumed to be relatively removed from the influence of important faults at depth, the vertical distribution of faults is relatively uniform. Calcite occurs mainly in two general zones, voids in welded portions of the Paintbrush Tuff, and in a deeper zone, mostly below 3,500 feet. Calcite is least abundant in USW G-4, which may reflect the fewer faults and fractures encountered in that drill hole.« less
  • This document is an annual report describing investigations of natural groundwater hazards at the proposed Yucca Mountain, Nevada High-Level Nuclear Waste Repository.This document describes research studies of the origin of near surface calcite/silica deposits at Yucca Mountain. The origin of these deposits is controversial and the authors have extended and strengthened the basis of their arguments for epigenetic, metasomatic alteration of the tuffs at Yucca Mountain. This report includes stratigraphic, mineralogical, and geochronological information along with geochemical data to support the conclusions described by Livingston and Szymanski, and others. As part of their first annual report, they take this opportunitymore » to clarify the technical basis of their concerns and summarize the critical geological field evidence and related information. Selected papers are indexed separately for inclusion in the Energy Science and Technology Database.« less
  • Drill-hole USW-G1 is one of series of test holes drilled in the vicinity of Yucca Mountain to acquire geologic, geophysical, hydrologic, and geochemical data to determine the feasibility of using the area for long-term storage of nuclear waste. The borehole is at lat 36{sup 0}52`00" N., long 116{sup 0}27`29" W.; the collar elevation is 4348.6 ft above mean sea level. The hole was drilled to 6000 ft. The radioelement contents (radium equivalent uranium (RaeU), thorium, and potassium) of samples collected from drill hole USW-G1 were measured to characterize the geologic units penetrated by the hole, to determine the homogeneity ofmore » the units, and to ascertain where redistribution of the radioelements may have occurred. Evidence of radioelement migration is important in potential waste-disposal sites because it suggests previous fluid movement through permeable sections of the geologic units that, in turn, reflects the relative permeability and physical competence of the units. Thorium is insoluble in high-temperature fluids or groundwater, and variations in its content probably indicate variations in original magma composition or variations in the physical mechanisms of eruptive processes. In contrast, RaeU and potassium are more soluble, and variations in the concentrations of these radioelements that are independent of thorium variations probably indicate postemplacement alteration. 7 refs., 2 figs., 2 tabs.« less
  • Yucca Mountain is being studied as a potential site in southern Nevada for an underground high-level nuclear waste repository. A major consideration for selecting this site is the presence of abundant zeolites in Miocene ash-flow tuffs underlying the region. We have studied the distribution and chemistry of diagenetic minerals at Yucca Mountain using optical petrography, x-ray powder diffraction, electron microanalysis, and x-ray fluorescence spectrometry to identify factors controlling the distribution of these minerals and to understand the diagenetic history at Yucca Mountain. Diagenetic alteration is best developed in nonwelded ash-flow tuffs and in the nonwelded tops and bottoms of weldedmore » ash-flow cooling units having crystallized interiors. These nonwelded tuffs were vitric tuffs become progressively less hydrous with depth, and four diagenetic mineral zones are recognized beneath most of Yucca Mountain. 12 refs., 12 figs., 7 tabs.« less