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Title: Drift emplaced waste package thermal response

Abstract

Thermal calculations of the effects of radioactive waste decay heat on the potential repository at Yucca Mountain, Nevada, have been conducted by the Yucca Mountain Site Characterization Project (YMP) at Lawrence Livermore National Lab. (LLNL) in conjunction with the B&W Fuel Co. For a number of waste package spacings, these 3D transient calculations use the TOPAZ3D code to predict drift wall temperatures to 10,000 years following emplacement. Systematic temperature variation occurs as a function of fuel age at emplacement and Areal Mass Loading (AML) during the first few centuries after emplacement. After about 1000 years, emplacement age is not a strong driver on rock temperature; AML has a larger impact. High AMLs occur when large waste packages are emplaced end-to-end in drifts. Drift emplacement of equivalent packages results in lower rock temperatures than borehole emplacement. For an emplacement scheme with 50% of the drift length occupied by packages, an AML of 138 MTU/acre is about three times higher than the Site Characterization Plan-Conceptual Design (SCP-CD) value. With this higher AML (requiring only 1/3 of the SCP-CD repository footprint), peak drift wall temperatures do not exceed 160{degrees}C, but rock temperatures exceed the boiling point of water for about 3000 years. Thesemore » TOPAZ3D results have been compared with reasonable agreement with two other computer codes.« less

Authors:
; ;  [1];  [2];  [3]
  1. Lawrence Livermore National Lab., CA (United States)
  2. Lawrence Livermore National Lab., Las Vegas, NV (United States)
  3. B&W Fuel Co., Las Vegas, NV (United States)
Publication Date:
Research Org.:
American Nuclear Society, La Grange Park, IL (United States); American Society of Civil Engineers, New York, NY (United States)
OSTI Identifier:
60872
Report Number(s):
CONF-930408-Vol.1
TRN: 95:004833
DOE Contract Number:
W-7405-ENG-48
Resource Type:
Conference
Resource Relation:
Conference: 10. international high-level radioactive waste management conference, Las Vegas, NV (United States), 25-29 Apr 1993; Other Information: PBD: 1993; Related Information: Is Part Of High Level Radioactive Waste Management: Proceedings. Volume 1; PB: 1115 p.
Country of Publication:
United States
Language:
English
Subject:
05 NUCLEAR FUELS; 42 ENGINEERING NOT INCLUDED IN OTHER CATEGORIES; 54 ENVIRONMENTAL SCIENCES; YUCCA MOUNTAIN; SITE CHARACTERIZATION; HIGH-LEVEL RADIOACTIVE WASTES; UNDERGROUND DISPOSAL; RADIOACTIVE WASTE FACILITIES; THERMAL ANALYSIS; CONFIGURATION; COMPUTER CODES; Yucca Mountain Project

Citation Formats

Ruffner, D.J., Johnson, G.L., Platt, E.A., Blink, J.A., and Doering, T.W. Drift emplaced waste package thermal response. United States: N. p., 1993. Web.
Ruffner, D.J., Johnson, G.L., Platt, E.A., Blink, J.A., & Doering, T.W. Drift emplaced waste package thermal response. United States.
Ruffner, D.J., Johnson, G.L., Platt, E.A., Blink, J.A., and Doering, T.W. 1993. "Drift emplaced waste package thermal response". United States. doi:.
@article{osti_60872,
title = {Drift emplaced waste package thermal response},
author = {Ruffner, D.J. and Johnson, G.L. and Platt, E.A. and Blink, J.A. and Doering, T.W.},
abstractNote = {Thermal calculations of the effects of radioactive waste decay heat on the potential repository at Yucca Mountain, Nevada, have been conducted by the Yucca Mountain Site Characterization Project (YMP) at Lawrence Livermore National Lab. (LLNL) in conjunction with the B&W Fuel Co. For a number of waste package spacings, these 3D transient calculations use the TOPAZ3D code to predict drift wall temperatures to 10,000 years following emplacement. Systematic temperature variation occurs as a function of fuel age at emplacement and Areal Mass Loading (AML) during the first few centuries after emplacement. After about 1000 years, emplacement age is not a strong driver on rock temperature; AML has a larger impact. High AMLs occur when large waste packages are emplaced end-to-end in drifts. Drift emplacement of equivalent packages results in lower rock temperatures than borehole emplacement. For an emplacement scheme with 50% of the drift length occupied by packages, an AML of 138 MTU/acre is about three times higher than the Site Characterization Plan-Conceptual Design (SCP-CD) value. With this higher AML (requiring only 1/3 of the SCP-CD repository footprint), peak drift wall temperatures do not exceed 160{degrees}C, but rock temperatures exceed the boiling point of water for about 3000 years. These TOPAZ3D results have been compared with reasonable agreement with two other computer codes.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = 1993,
month =
}

Conference:
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  • Thermal calculations of the effects of radioactive waste decay heat on the I repository at Yucca Mountain, Nevada have been conducted by the Yucca Mountain Site Characterization Project (YMP) at Lawrence Livermore National Laboratory (LLNL) in conjunction with the B&W Fuel Company. For a number of waste package spacings, these 3D transient calculations use the TOPAZ3D code to predict drift wall temperatures to 10,000 years following emplacement. Systematic tcniperature variation occurs as a function of fuel age at emplacement and Areal Mass Loading (AML) during the first few centuries after emplacement. After about 1000 years, emplacement age is not amore » strong driver on rock temperature; AML has a larger impact. High AMLs occur when large waste packages are emplaced end-tocnd in drifts. Drift emplacement of equivalent packages results in lower rock teniperatures than borehole emplacement. For an emplacement scheme with 50% of the drift length occupied by packages, an AML of 138 MTU/acre is about three times higher than the Site Characterization Plan-Conceptual Design (SCP-CD) value. With this higher AML (requiring only 1/3 of the SCP-CD repository footprint), peak drift wall temperatures do not exceed 160*C, but rock temperatures excetd the boiling point of water for about 3000 years. These TOPAZ3D results Iiive been compared with reasonable agreement with two other computer codes.« less
  • This paper describes an analysis performed to determine the cool-down time of drifts in the prospective commercial nuclear waste repository in volcanic tuff at Yucca Mountain, Nevada. Two emplacement methods are currently being considered at Yucca Mountain. The reference configuration stores the high-level waste in short vertical boreholes, and the alternative configuration stores the waste in long horizontal boreholes. After emplacement operations for each emplacement drift are complete, the drift will be closed off from continuous ventilation. Given time, the radioactive decay of high-level waste will increase the rock temperature around access and emplacement drifts. Air cooling may be requiredmore » to reenter these drifts. The paper discusses the analysis procedure and computer programs used to evaluate the time to cool a drift to acceptable environmental conditions 50 years after emplacement of high-level waste. Key assumptions to the analysis are presented. The results of the study show that cooling either vertical or horizontal configuration emplacement drifts is possible in a reasonable period of time. 4 refs., 5 figs., 2 tabs.« less
  • Cylindrical waste canisters placed horizontally in the underground drifts of a nuclear repository will emit decay heat by convection to the surrounding air and by radiation heat transfer. In drifts with no forced air circulation, natural convection about the waste canisters will play an important role in controlling the temperature distribution inside the canisters and on the drift wall. Experiments were conducted to visualize the flow about model canisters and to measure the steady-state temperature distribution about the canister. The results show an enhancement in heat transfer when compared to heat flow between infinitely long eccentric horizontal cylinders. A discussionmore » of the observed flow regimes as a function of Rayleigh number is provided to describe the various experimental results.« less
  • Thermal evaluations of the multi-Purpose Canister in repository emplacement have been performed by the Yucca Mountain Site Characterization Project Managing and Operating Contractor (YMP-M&O). Thermal effects have been a major study area of the Mined Geologic Disposal System (MGDS). In the past the project has concentrated primarily on borehole-emplaced waste packages, but the Multi-Purpose Canister (MPC) with a capacity of twenty-one pressurized water reactor (PWR) fuel assemblies (or more) will likely be drift emplaced with a multi-barrier disposal container or overpack. This study investigates the thermal behavior of the waste package/MPC and its effect on the repository near-field. Results indicatemore » that peak internal temperatures occur one to five years post emplacement, and the timing of the peak is highly dependent on the choice of design basis fuel and thermal loading. The maximum acceptable capacity of the MPC, with ten year old fuel, was determined to be twenty-one PWRs based on the current peak temperature goal of 350{degrees}C; however, higher capacities can be achieved if older fuel is substituted.« less
  • In a 1993 performance assessment, the uncertainty associated with using panel-scale thermo-hydrologic analyses to define the near-field environment in the vicinity of the waste packages was identified as one of the major factors impacting the predicted performance. This was because of the impact of the thermo-hydrologic regime on the initiation of aqueous corrosion as well as the rate of corrosion, rate of waste form dissolution (due to the uncertainty in the percent of the waste form surface covered by water film), solubility limits, and the effective diffusion through the waste package and engineered barrier. This document presents an initial attemptmore » to incorporate, in a more representative fashion, the anticipated thermo-hydrologic response in the vicinity of in-drift emplaced waste packages into the post-closure performance assessment. It illustrates some of the issues which must be resolved prior to justifying the inclusion of these representations into the assessment.« less