Effect of low-level radioactive waste leachate on antioxidant depletion in HDPE geo-membranes - 15135

Conference · Wed Jul 01 04:00:00 EDT 2015

OSTI ID:22822694

Tian, Kuo; Yang, Youming; Benson, Craig H.; Tinjum, James M. ^[1]

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1. University of Wisconsin-Madison (United States)

Low-level radioactive waste (LLW) and mixed waste (MW) disposal facilities in the US are required to have a service life in excess of 1000 yr. Understanding the rate of degradation of high-density polyethylene (HDPE) geo-membranes (GMs) used in barriers of LLW and MW facilities is necessary to assess their service life. HDPE GMs undergo degradation in three stages: antioxidant depletion (Stage I), induction time (stage II), and polymer degradation (Stage III). For LLW and MW facilities, these degradation mechanisms must be assessed with the GM in contact with leachates representative of LLW or MW. This paper focuses on antioxidant depletion in LLW leachate. HDPE GM coupons (2-mm thick) were immersed in radioactive synthetic leachate (RSL) with chemistry representative of leachate in LLW disposal facilities operated by the US Department of Energy's environmental restoration programs. Depletion was assessed at four temperatures (25, 50, 70, and 90 deg.C). Comparative tests were conducted with non-radioactive synthetic leachate (NSL), which has the same chemistry as RSL except radionuclides are excluded. Control tests were conducted with deionized (DI) water. Specimens were removed periodically and tested to determine their mechanical and chemical properties. Antioxidant depletion was measured by both standard and high-pressure oxidative induction time (OIT) tests. The rate of antioxidant depletion in RSL is statistically no different than depletion in NSL. Extrapolating the laboratory data at elevated temperatures to a typical LLW liner at 15 deg.C via Arrhenius modeling showed that the time for antioxidant depletion for a GM in a composite liner is approximately 650 yr when exposed to LLW leachate. Actual service life of the GM will be longer. (authors)

• Research Organization: WM Symposia, Inc., PO Box 27646, 85285-7646 Tempe, AZ (United States)
• OSTI ID: 22822694
• Report Number(s): INIS-US--19-WM-15135
• Country of Publication: United States
• Language: English

Related Subjects

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
ANTIOXIDANTS
CHEMICAL PROPERTIES
CONTROL
DIFFUSION BARRIERS
LEACHATES
LOW-LEVEL RADIOACTIVE WASTES
MECHANICAL PROPERTIES
MEMBRANES
OXIDATION
POLYETHYLENES
PRESSURE RANGE MEGA PA 10-100
RADIOACTIVE WASTE DISPOSAL
SERVICE LIFE
SIMULATION
TEMPERATURE DEPENDENCE
US DOE
WATER