skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Antioxidant Depletion and Service Life Prediction for HDPE Geomembranes Exposed to Low-Level Radioactive Waste Leachate

Abstract

Antioxidant depletion was evaluated in high-density polyethylene (HDPE) geomembrane (GM) coupons immersed in radioactive synthetic leachate (RSL) representative of leachate in low-level radioactive waste (LLW) disposal facilities operated by the U.S. Department of Energy’s environmental restoration programs. Depletion was assessed at four temperatures (25, 50, 70, and 90°C). Comparative tests were conducted with nonradioactive synthetic leachate (NSL) having the same chemistry as RSL, except radionuclides were excluded. Control tests were conducted with deionized (DI) water. One-sided exposure tests were also conducted with the HDPE GM in RSL at 70 and 90°C. Specimens were removed periodically and tested to determine antioxidant depletion, melt flow index (MFI), crystallinity, and stress crack resistance. Standard and high-pressure oxidative induction time (OIT) tests were conducted to measure antioxidant depletion. Antioxidant depletion rates in RSL were only slightly greater than those in NSL, indicating that radionuclides in the LLW leachate had only minor effect on antioxidant depletion. Antioxidant depletion in RSL and NSL occurred 1.1–1.9 times faster than in DI water. Antioxidant depletion in HDPE GMs exposed to RSL and NSL at 90°C was complete after 12 months. MFI decreased systematically after 15 months of immersion, which is indicative of crosslinking due to oxidation. Crystallinity alsomore » decreased slightly after 12 months, whereas stress crack resistance (SCR) showed no trend over the immersion period. Arrhenius modeling was used to extrapolate the laboratory data at elevated temperatures to a typical LLWliner at 15°C. Predicted time for antioxidant depletion for a 2-mm-thick HDPE GM in a composite liner in contact with LLW leachate is estimated to be 730 years. The total service life of HDPE GMs in contact with LLWleachate is estimated to be at least 1975 years.« less

Authors:
 [1];  [1];  [2];  [2]
  1. Univ. of Virginia, Charlottesville, VA (United States)
  2. Univ. of Wisconsin, Madison, WI (United States)
Publication Date:
Research Org.:
Vanderbilt Univ., Nashville, TN (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1425968
Grant/Contract Number:
FC01-06EW07053
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Geotechnical and Geoenvironmental Engineering
Additional Journal Information:
Journal Volume: 143; Journal Issue: 6; Journal ID: ISSN 1090-0241
Publisher:
American Society of Civil Engineers
Country of Publication:
United States
Language:
English
Subject:
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; Radioactive waste; Mixed waste; Geomembrane; Degradation; Antioxidant; High-density polyethylene.

Citation Formats

Tian, Kuo, Benson, Craig H., Tinjum, James M., and Edil, Tuncer B. Antioxidant Depletion and Service Life Prediction for HDPE Geomembranes Exposed to Low-Level Radioactive Waste Leachate. United States: N. p., 2017. Web. doi:10.1061/(ASCE)GT.1943-5606.0001643.
Tian, Kuo, Benson, Craig H., Tinjum, James M., & Edil, Tuncer B. Antioxidant Depletion and Service Life Prediction for HDPE Geomembranes Exposed to Low-Level Radioactive Waste Leachate. United States. doi:10.1061/(ASCE)GT.1943-5606.0001643.
Tian, Kuo, Benson, Craig H., Tinjum, James M., and Edil, Tuncer B. Thu . "Antioxidant Depletion and Service Life Prediction for HDPE Geomembranes Exposed to Low-Level Radioactive Waste Leachate". United States. doi:10.1061/(ASCE)GT.1943-5606.0001643. https://www.osti.gov/servlets/purl/1425968.
@article{osti_1425968,
title = {Antioxidant Depletion and Service Life Prediction for HDPE Geomembranes Exposed to Low-Level Radioactive Waste Leachate},
author = {Tian, Kuo and Benson, Craig H. and Tinjum, James M. and Edil, Tuncer B.},
abstractNote = {Antioxidant depletion was evaluated in high-density polyethylene (HDPE) geomembrane (GM) coupons immersed in radioactive synthetic leachate (RSL) representative of leachate in low-level radioactive waste (LLW) disposal facilities operated by the U.S. Department of Energy’s environmental restoration programs. Depletion was assessed at four temperatures (25, 50, 70, and 90°C). Comparative tests were conducted with nonradioactive synthetic leachate (NSL) having the same chemistry as RSL, except radionuclides were excluded. Control tests were conducted with deionized (DI) water. One-sided exposure tests were also conducted with the HDPE GM in RSL at 70 and 90°C. Specimens were removed periodically and tested to determine antioxidant depletion, melt flow index (MFI), crystallinity, and stress crack resistance. Standard and high-pressure oxidative induction time (OIT) tests were conducted to measure antioxidant depletion. Antioxidant depletion rates in RSL were only slightly greater than those in NSL, indicating that radionuclides in the LLW leachate had only minor effect on antioxidant depletion. Antioxidant depletion in RSL and NSL occurred 1.1–1.9 times faster than in DI water. Antioxidant depletion in HDPE GMs exposed to RSL and NSL at 90°C was complete after 12 months. MFI decreased systematically after 15 months of immersion, which is indicative of crosslinking due to oxidation. Crystallinity also decreased slightly after 12 months, whereas stress crack resistance (SCR) showed no trend over the immersion period. Arrhenius modeling was used to extrapolate the laboratory data at elevated temperatures to a typical LLWliner at 15°C. Predicted time for antioxidant depletion for a 2-mm-thick HDPE GM in a composite liner in contact with LLW leachate is estimated to be 730 years. The total service life of HDPE GMs in contact with LLWleachate is estimated to be at least 1975 years.},
doi = {10.1061/(ASCE)GT.1943-5606.0001643},
journal = {Journal of Geotechnical and Geoenvironmental Engineering},
number = 6,
volume = 143,
place = {United States},
year = {Thu Jun 01 00:00:00 EDT 2017},
month = {Thu Jun 01 00:00:00 EDT 2017}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record

Save / Share:
  • A major issue in the use of geomembranes for waste containment is an estimate of the material`s durability (i.e., its lifetime) to various aging phenomena. For high density polyethylene geomembranes, which are the focus of this study, there are three stages in assessing lifetime: depletion of antioxidants, induction time, and time to reach half-life of a relevant engineering property. This paper addresses the first stage of these three sequential processes. Twenty laboratory incubation devices were made to simulate landfill conditions. Four sets of five columns were maintained at elevated temperatures of 85, 75, 65 and 55 C. Samples were retrievedmore » at various intervals over a 24-month incubation period. Various physical, mechanical, and chemical properties were evaluated. The depletion of antioxidants in the incubated samples was monitored using both standard and high pressure oxidative induction time tests. Arrhenius modeling was used on the data to extrapolate the antioxidant lifetime to a typical landfill site temperature of 20 C. The resulting predicted time was 200 to 215 years. Also, it should be emphasized that within this period of time the physical and mechanical properties of the incubated samples remained unchanged.« less
  • Using an exposed geomembrane an interim measure to cover a closed, Low-Level Radioactive Waste Disposal Area requires unique design and construction considerations. In response to a Resource Conservation and Recovery Act Administrative Consent Order, the New York State Energy Research and Development Authority (NYSERDA) used very low-density polyethylene (VLDPE) geomembrane as an interim measure to cover two soil-capped, grass-covered waste trenches to address a rapid increase in water accumulation in the trenches. Two years later, NYSERDA covered the remaining grass-covered trench caps with a reinforced ethylene interpolymer alloy (EIA-R) geomembrane to reduce water accumulation in these trenches. This paper addressesmore » the differences in geomembrane materials and discusses the lessons learned during design, construction, and operation since installation of the covers. Discussed are the successes and obstacles regarding the use of both geomembrane materials as an exposed cover, selecting the geomembrane materials, anchoring the geomembrane from wind uplift, and mitigating the increased surface water runoff from the geomembrane covered area.« less
  • No abstract prepared.
  • Concrete barriers will be used as intimate parts of systems for isolation of low level radioactive wastes subsequent to disposal. This work reviews mathematical models for estimating the degradation rate of concrete in typical service environments. The models considered cover sulfate attack, reinforcement corrosion, calcium hydroxide leaching, carbonation, freeze/thaw, and cracking. Additionally, fluid flow, mass transport, and geochemical properties of concrete are briefly reviewed. Example calculations included illustrate the types of predictions expected of the models. 79 refs., 24 figs., 6 tabs.