EMPLACEMENT DRIFT INVERT-LOW STEEL EVALUATION

Tang, M. E. Taylor and D. H.

United States. Department of Energy. Yucca Mountain Project Office.

关键词: Carbon Steels;    Testing;    Capacity;    Bearings;    Steels;   

DOI  :  10.2172/889268
RP-ID  :  TDR-EDS-ST-000002
RP-ID  :  DE-AC08-91RW00134
RP-ID  :  889268

美国|英语

来源: UNT Digital Library

【 摘 要 】

This technical report evaluates and develops options for reducing the amount of steel in the emplacement drift invert. Concepts developed in the ''Invert Configuration and Drip Shield Interface'' were evaluated to determine material properties required for the proposed invert concepts. Project requirements documents prescribe the use of a carbon steel frame for the invert with a granular material of crushed tuff as ballast. The ''Invert Configuration and Drip Shield Interface'' developed three concepts: (1) All-Ballast Invert; (2) Modified Steel Invert with Ballast; and (3) Steel Tie with Ballast Invert. Analysis of the steel frame members, runway beams, and guide beams, for the modified steel invert with ballast, decreased the quantity of steel in the emplacement drift invert, however a substantial steel support frame for the gantry and waste package/pallet assembly is still required. Use of one of the other two concepts appears to be an alternative to the steel frame and each of the concepts uses considerably less steel materials. Analysis of the steel tie with ballast invert shows that the bearing pressure on the ballast under the single steel tie, C 9 x 20, loaded with the waste package/pallet assembly, drip shield, and backfill exceeds the upper bound of the allowable bearing capacity for tuff used in this study. The single tie, C 10 x 20, will also fail for the same loading condition except for the tie length of 4.2 meters and longer. Analysis also shows that with two ties, C 9 or 10 x 20's, the average ballast pressure is less than the allowable bearing capacity. Distributing the waste package/pallet, drip shield, and backfill loads to two steel ties reduces the contact bearing pressure. Modifying the emplacement pallet end beams to a greater width, reducing the tie spacing, and increasing the width of the ties would ensure that the pallet beams are always supported by two steel ties. Further analysis is required to determine compatible tie size and spacing and pallet beam width. Testing is also required to determine the bearing capacity of the tuff materials. Analysis of the all-ballast invert shows that the waste package/pallet assembly, as currently designed, can be supported by the compacted crushed tuff. The drip shield and related backfill loads cannot be supported by the compacted crushed tuff because of the narrow base angle that currently supports the drip shield. Increasing the width of the base angle of the drip shield will better distribute the drip shield and backfill load to the compacted crushed tuff. Testing is required to determine the bearing capacity of the tuff materials. Emplacement/retrieval equipment will also require analysis and development to be compatible with the all-ballast invert.