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Title: Heat‐Generating Nuclear Waste in Salt: Field Testing and Simulation

Journal Article · · Vadose Zone Journal
 [1];  [2];  [2];  [2];  [1];  [3];  [1];  [1]
  1. EES‐16: Computational Earth Science MS T003, Los Alamos National Lab. Los Alamos NM 87545
  2. Los Alamos National Lab. Carlsbad Field Office Carlsbad NM 88221
  3. Neptune and Company Lakewood CO 80215
+ Show Author Affiliations

Core Ideas A field‐scale experiment and numerical simulations confirm salt backfill behavior. Simulations closely match temperature around and under the piled salt backfill. Results indicate limited dissolution–precipitation reactions around the heat source. Alteration of backfill is unlikely if the drift is allowed to dry before emplacement. Investigations relating to in‐drift disposal of heat‐generating nuclear waste in salt have raised questions about heat–brine interactions in the unsaturated run‐of‐mine (RoM) salt pile used as backfill. These interactions have the potential to change the structure of the RoM salt surrounding the canister, possibly altering long‐term containment of the source. An experiment is in progress at the Waste Isolation Pilot Plant (WIPP), New Mexico, in which a heated canister was placed on the floor of an open drift, covered in a pile of RoM salt, and energized with 1000 W. Temperature in the RoM salt pile had stabilized after about 15 d, allowing evaluation of the heat‐up period of the ongoing experiment. Using a multiphase porous flow simulator that has been modified to handle salt‐specific coupled processes, we examined coupled thermal–hydrological–chemical behavior in the RoM salt pile. Our simulations suggest that for the relatively dry cases examined, porosity changes within RoM salt in a generic salt repository are likely to be minor in the period between waste emplacement and plastic closure of the drift. The primary sensitivity for porosity change is to the early moisture content of the RoM salt used to cover the canister. Secondary influences include moisture availability from the disturbed rock zone (DRZ) surrounding the drift and the capillary pressure ratio between the DRZ and the RoM salt. Early changes in porosity and permeability may be affected by moisture content, but this was not observed in the test. Such changes would be most likely to occur when using damp RoM salt or if waste is emplaced in a drift immediately following opening of the drift before evaporative dewatering of the drift walls occurs.

Research Organization:
Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
Sponsoring Organization:
USDOE Office of Nuclear Energy (NE); USDOE Office of Environmental Management (EM)
Grant/Contract Number:
89233218CNA000001
OSTI ID:
1598698
Alternate ID(s):
OSTI ID: 1499365; OSTI ID: 1598700
Report Number(s):
LA-UR-18-31862
Journal Information:
Vadose Zone Journal, Journal Name: Vadose Zone Journal Vol. 18 Journal Issue: 1; ISSN 1539-1663
Publisher:
Wiley Blackwell (John Wiley & Sons)Copyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 2 works
Citation information provided by
Web of Science

References (15)

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Development of a U.S. Nuclear Waste Repository Research Program in Salt journal October 2012
Historical background on performance assessment for the Waste Isolation Pilot Plant journal September 2000
Estimating liquid fluxes in thermally perturbed fractured rock using measured temperature profiles journal August 2006
Joule–Thomson Effects on the Flow of Liquid Water journal August 2014
Geohydromechanical processes in the Excavation Damaged Zone in crystalline rock, rock salt, and indurated and plastic clays—in the context of radioactive waste disposal journal January 2005
Untangling Diffusion from Advection in Unsaturated Porous Media: Experimental Data, Modeling, and Parameter Uncertainty journal January 2009
Porosity Variations in Saline Media Induced by Temperature Gradients: Experimental Evidences and Modelling journal August 2011
Review of Porous Media Enhanced Vapor-Phase Diffusion Mechanisms, Models, and Data—Does Enhanced Vapor-Phase Diffusion Exist? journal January 1998
Hydrous Mineral Dehydration Around Heat-Generating Nuclear Waste in Bedded Salt Formations journal May 2015
Empirical equations for the thermodynamic properties of aqueous sodium chloride journal October 2003
Thermal Modeling of High-Level Nuclear Waste Disposal in a Salt Repository journal September 2014
Coupled Processes Modeling in Rock Salt and Crushed Salt Including Halite Solubility Constraints: Application to Disposal of Heat-Generating Nuclear Waste journal April 2018
Petrophysical and Capillary Properties of Compacted Salt journal August 2006
Permeability of porous solids journal January 1961

Figures / Tables (13)

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Table 1(p. 8)table Table 1
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