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Title: WIPP Gas-Generation Experiments

Abstract

An experimental investigation was conducted for gas generation in contact-handled transuranic (CH TRU) wastes subjected for several years to conditions similar to those expected to occur at the Waste Isolation Pilot Plant (WIPP) should the repository eventually become inundated with brine. Various types of actual CH TRU wastes were placed into 12 corrosion-resistant vessels. The vessels were loosely filled with the wastes, which were submerged in synthetic brine having the same chemical composition as that in the WIPP vicinity. The vessels were also inoculated with microbes found in the Salado Formation at WIPP. The vessels were sealed, purged, and the approximately 750 ml headspace in each vessel was pressurized with nitrogen gas to approximately 146 atmospheres to create anoxic conditions at the lithostatic pressure estimated in the repository were it to be inundated. The temperature was maintained at the expected 30°C. The test program objective was to measure the quantities and species of gases generated by metal corrosion, radiolysis, and microbial activity. These data will assist in the specification of the rates at which gases are produced under inundated repository conditions for use in the WIPP Performance Assessment computer models. These experiments were very carefully designed, constructed, instrumented, and performed.more » Approximately 6 1/2 years of continuous, undisturbed testing were accumulated. Several of the vessels showed significantly elevated levels of generated gases, virtually all of which was hydrogen. Up to 4.2% hydrogen, by volume, was measured. Only small quantities of other gases, principally carbon dioxide, were detected. Gas generation was found to depend strongly on the waste composition. The maximum hydrogen generation occurred in vessels containing carbon steel. Visual examination of carbon-steel coupons confirmed the correspondence between the extent of observable corrosion and hydrogen generation. Average corrosion penetration rates in carbon-steel of up to 2.3 microns per year were deduced. Conversion of carbon to carbon dioxide was calculated to be as high as 4.7 µg mol/yr/g carbon. Carbon monoxide was detected in only two waste compositions, and methane was detected in only one. In all three of these cases, the concentrations of these lesser gases detected were barely above the detection limits. No hydrogen sulfide was ever detected. Initial rates of hydrogen generation measured in the carbon-steel-bearing wastes during the first year of testing did not always correspond to rates measured over the longer term. Compared to the long-term trends, the initial gas-generation rates for some waste types were higher, for some lower, and for others remained constant. Although carbon-steel corrosion was clearly the dominant hydrogen generator, the rates of generation were found to be reduced in test vessels where the same quantity of carbon steel was co-mingled with other waste types. This is a beneficial phenomenon relative to performance of the WIPP repository. Statistical analyses of the results were made to quantify these negative interaction effects. Electron microscopy analyses of the carbon-steel coupons revealed that corrosion products were predominantly iron chlorides and oxides. Iron, chlorine, oxygen, uranium, magnesium, calcium, aluminum, silicon were all present in the corrosion products. No americium nor neptunium, both present in the wastes, were detected in any of the corrosion products. All« less

Authors:
; ;
Publication Date:
Research Org.:
Idaho National Laboratory (INL)
Sponsoring Org.:
DOE - NE
OSTI Identifier:
920400
Report Number(s):
INL/EXT-07-12631
TRN: US0805311
DOE Contract Number:
DE-AC07-99ID-13727
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
99 - GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE; ALPHA-BEARING WASTES; ALUMINIUM; CARBON; CARBON DIOXIDE; CARBON MONOXIDE; CARBON STEELS; CHEMICAL COMPOSITION; CORROSION; CORROSION PRODUCTS; ELECTRON MICROSCOPY; GASES; HYDROGEN; HYDROGEN GENERATORS; HYDROGEN SULFIDES; IRON CHLORIDES; WASTES; WIPP; CH-TRU; contact-handled transuranic wastes; gas generation

Citation Formats

Frank S. Felicione, Steven M. Frank, and Dennis D. Keiser. WIPP Gas-Generation Experiments. United States: N. p., 2007. Web. doi:10.2172/920400.
Frank S. Felicione, Steven M. Frank, & Dennis D. Keiser. WIPP Gas-Generation Experiments. United States. doi:10.2172/920400.
Frank S. Felicione, Steven M. Frank, and Dennis D. Keiser. Tue . "WIPP Gas-Generation Experiments". United States. doi:10.2172/920400. https://www.osti.gov/servlets/purl/920400.
@article{osti_920400,
title = {WIPP Gas-Generation Experiments},
author = {Frank S. Felicione and Steven M. Frank and Dennis D. Keiser},
abstractNote = {An experimental investigation was conducted for gas generation in contact-handled transuranic (CH TRU) wastes subjected for several years to conditions similar to those expected to occur at the Waste Isolation Pilot Plant (WIPP) should the repository eventually become inundated with brine. Various types of actual CH TRU wastes were placed into 12 corrosion-resistant vessels. The vessels were loosely filled with the wastes, which were submerged in synthetic brine having the same chemical composition as that in the WIPP vicinity. The vessels were also inoculated with microbes found in the Salado Formation at WIPP. The vessels were sealed, purged, and the approximately 750 ml headspace in each vessel was pressurized with nitrogen gas to approximately 146 atmospheres to create anoxic conditions at the lithostatic pressure estimated in the repository were it to be inundated. The temperature was maintained at the expected 30°C. The test program objective was to measure the quantities and species of gases generated by metal corrosion, radiolysis, and microbial activity. These data will assist in the specification of the rates at which gases are produced under inundated repository conditions for use in the WIPP Performance Assessment computer models. These experiments were very carefully designed, constructed, instrumented, and performed. Approximately 6 1/2 years of continuous, undisturbed testing were accumulated. Several of the vessels showed significantly elevated levels of generated gases, virtually all of which was hydrogen. Up to 4.2% hydrogen, by volume, was measured. Only small quantities of other gases, principally carbon dioxide, were detected. Gas generation was found to depend strongly on the waste composition. The maximum hydrogen generation occurred in vessels containing carbon steel. Visual examination of carbon-steel coupons confirmed the correspondence between the extent of observable corrosion and hydrogen generation. Average corrosion penetration rates in carbon-steel of up to 2.3 microns per year were deduced. Conversion of carbon to carbon dioxide was calculated to be as high as 4.7 µg mol/yr/g carbon. Carbon monoxide was detected in only two waste compositions, and methane was detected in only one. In all three of these cases, the concentrations of these lesser gases detected were barely above the detection limits. No hydrogen sulfide was ever detected. Initial rates of hydrogen generation measured in the carbon-steel-bearing wastes during the first year of testing did not always correspond to rates measured over the longer term. Compared to the long-term trends, the initial gas-generation rates for some waste types were higher, for some lower, and for others remained constant. Although carbon-steel corrosion was clearly the dominant hydrogen generator, the rates of generation were found to be reduced in test vessels where the same quantity of carbon steel was co-mingled with other waste types. This is a beneficial phenomenon relative to performance of the WIPP repository. Statistical analyses of the results were made to quantify these negative interaction effects. Electron microscopy analyses of the carbon-steel coupons revealed that corrosion products were predominantly iron chlorides and oxides. Iron, chlorine, oxygen, uranium, magnesium, calcium, aluminum, silicon were all present in the corrosion products. No americium nor neptunium, both present in the wastes, were detected in any of the corrosion products. All},
doi = {10.2172/920400},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue May 01 00:00:00 EDT 2007},
month = {Tue May 01 00:00:00 EDT 2007}
}

Technical Report:

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  • The potential for generation of gases in transuranic (TRU) waste by microbial activity, chemical interactions, corrosion, and radiolysis was addressed in the Argonne National Laboratory-West (ANL-West) Gas-Generation Experiments (GGE). Data was collected over several years by simulating the conditions in the Waste Isolation Pilot Plant (WIPP) after the eventual intrusion of brine into the repository. Fourteen test containers with various actual TRU waste immersed in representative brine were inoculated with WIPP-relevant microbes, pressurized with inert gases, and kept in an inert-atmosphere environment for several years to provide estimates of the gas-generation rates that will be used in computer models formore » future WIPP Performance Assessments. Modest temperature variations occurred during the long-term ANL-West experiments. Although the experiment temperatures always remained well within the experiment specifications, the small temperature variation was observed to affect the test container pressure far more than had been anticipated. In fact, the pressure variations were so large, and seemingly erratic, that it was impossible to discern whether the data was even valid and whether the long-term pressure trend was increasing, decreasing, or constant. The result was that no useful estimates of gas-generation rates could be deduced from the pressure data. Several initial attempts were made to quantify the pressure fluctuations by relating these to the measured temperature variation, but none was successful. The work reported here carefully analyzed the pressure measurements to determine if these were valid or erroneous data. It was found that a thorough consideration of the physical phenomena that were occurring can, in conjunction with suitable gas laws, account quite accurately for the pressure changes that were observed. Failure of the earlier attempts to validate the data was traced to the omission of several phenomena, the most important being the variation in the headspace volume caused by thermal expansion and contraction within the brine and waste. A further effort was directed at recovering useful results from the voluminous archived pressure data. An analytic methodology to do this was developed. This methodology was applied to each archived pressure measurement to nullify temperature and other effects to yield an adjusted pressure, from which gas-generation rates could be calculated. A review of the adjusted-pressure data indicated that generated-gas concentrations among these containers after approximately 3.25 years of test operation ranged from zero to over 17,000 ppm by volume. Four test containers experienced significant gas generation. All test containers that showed evidence of significant gas generation contained carbon-steel in the waste, indicating that corrosion was the predominant source of gas generation.« less
  • Microbial processes involved in gas generation from degradation of the organic constituents of transuranic waste under conditions expected at the Waste Isolation Pilot Plant (WIPP) repository are being investigated at Brookhaven National Laboratory. These laboratory studies are part of the Sandia National Laboratories -- WIPP Gas Generation Program. Gas generation due to microbial degradation of representative cellulosic waste was investigated in short-term (< 6 months) and long-term (> 6 months) experiments by incubating representative paper (filter paper, paper towels, and tissue) in WIPP brine under initially aerobic (air) and anaerobic (nitrogen) conditions. Samples from the WIPP surficial environment and undergroundmore » workings harbor gas-producing halophilic microorganisms, the activities of which were studied in short-term experiments. The microorganisms metabolized a variety of organic compounds including cellulose under aerobic, anaerobic, and denitrifying conditions. In long-term experiments, the effects of added nutrients (trace amounts of ammonium nitrate, phosphate, and yeast extract), no nutrients, and nutrients plus excess nitrate on gas production from cellulose degradation.« less
  • The WIPP Simulated CH and RH TRU Waste Tests are a collection of related technology experiments and operational demonstrations. These technology experiments (TE) evaluate the in situ durability or containment integrity (i.e., the corrosion behavior and crush resistance) of contact-handled transuranic waste (CH TRU) drums and remote-handled transuranic waste (RH TRU) canisters. Also to be evaluated are the interactions of the waste containers and several backfill materials, and the migration behavior 'of nonradioactive, chemical tracers representative of radionuclides eventually released from the waste containers in the long term. The behavior of TRU waste forms will not be evaluated in thesemore » tests. The degradation behavior of TRU waste matrices was characterized previously in the laboratory, and is reviewed in Section 9.1. All CH TRU drums and RH TRU canisters used in these tests are simulated only in the sense that they contain no radioactive materials.« less
  • The US Department of Energy manages an R and D Program to provide a technical basis for systems designs and safety and environmental assessments for future repositories of radioactive wastes resulting from US defense activities. The Waste Isolation Pilot Plant (WIPP) in southeast New Mexico is being developed with that Program as an R and D facility to demonstrate the safe disposal of such wastes in bedded salt. The Simulated-Waste Experiments (SWEs) refer to the in situ tests (without radioactivity) in the WIPP R and D Program that address the technical issues of isolating radioactive wastes in bedded salt. Themore » SWEs include tests that concern the program areas of repository development and interactions of the waste package with the host rock. Data obtained from these tests will be used in evaluating performance assessment models and in developing a technical basis for future repository designs and operations.« less
  • The Department of Energy (DOE) has developed the Waste Isolation Pilot Plant (WIPP) for the purpose of demonstrating safe management, storage, and disposal of radioactive transuranic (TRU) waste generated by U.S. defense programs. The WIPP is located in southeastern New Mexico, and the underground facilities of the WIPP (i.e., experimental rooms, disposal rooms, etc.) are sited in the bedded salt of the Salado Formation at a depth of about 660 meters. The DOE has authorized the continuance of scientific research and engineering analysis related to the performance of the WIPP repository. One area of additional research relates to characterization ofmore » the mechanical and hydrological properties of anhydrite interbeds within the Salado Formation. These anhydrite interbeds have been penetrated by the shafts that provide access to the underground facilities and also lie in close proximity to the proposed radioactive waste disposal rooms at the repository horizon. Properties of particular interest are mechanical strength, deforrnational behavior, and fluid transport properties such as permeability. These properties will be used in calculationskmalyses of the mechanical and hydrological behavior of the anhydrite, in particular, and the shaft sealing system and disposal rooms, in general.« less