2 Hydrogeology

Sunday, 28 October 2007
8:00 AM - 12:00 PM

VALLEY OF KINGS, POSITIVE AND NEGATIVE YUCCA MOUNTAIN ANALOGUES

Paper number: 2-2
Program: Technical Sessions
Time: 8:15 AM – 8:30 AM

Authors

Abstract

Natural and man-made objects and processes have analogue value and are used by investigators seeking to develop nuclear waste repositories. When properly applied, analogues can add confidence to site investigations and performance assessments (TSPA). Repositories must be capable of isolating wastes for hundreds of thousands of years despite the fact that complex numerical models used in TSPA cannot be validated. Yucca Mountain Project (YMP) scientists offer a variety of analogues to support performance: persistence of capillary barriers and fragile artifacts, presence of a dry out zone, size of rock falls, tunnel stability, source term release rates, reconstruction of paleo-and future-climate states, reliability of TSPA models and others. Although both positive and negative analogues are useful, observations that support performance tend to be emphasized. The absence of objects cannot prove that they never existed. However, processes that could lead to their demise can and should be investigated.

63 tombs are known in the Valley of Kings, Luxor, Egypt. Some date from 1550 to 1100 centuries BC. Water remains the single most destructive agent. Some have been badly damaged by flooding of unprotected entrances. All continue to be damaged by vadose water that migrates along joints, fractures, zone of fracture concentration and faults within Thebes Limestone (Eocene). Even during smaller storms, surface water accumulates within exposed fractures, contributing to episodic flow. Damage to interior decorations is cumulative and is more intense at structural intersections. Roof collapse is especially serious in KV- 13, 18, 32 and 47. Rock falls have raised ceilings by 2.4 m even where passages are only 1.5 to 2 m wide. 1.0 to 2.0 m-sized blocks have fallen in some passages closed for safety. Tunnel stability is related to structure, changes in water content, flooding, excessive stone removal, stacking of tombs and unstable substrate. The Valley of Kings could afford YMP scientists and engineers new examples of both positive (e.g. artifact preservation within the vadose zone) and negative analogues (episodic flow and tunnel stability).