Chapter 4
DESCRIPTION OF THE CONTAINMENT STRICTURE
4.1
GeneralObservations
The key-wall and concrete dome appear to be well finished «
consist of very good quality concrete.
Some slightly open joints] are
extends through the midpoint of 6 of the 358 panels.
Most of
cracks appear to have resulted from nermal shrinkage of the concz
The existing cracks may become larger, and similar cracks may de
in other panels.
The principal effect of this cracking is to reduce the eff
size of the panel, functioning as riprap, to approxima*ely 15
half.
Neitger moisture movement nor future possible fissure to
underlying membrane is an issue with respect to durability of the
4.2 The Drilling Program
At the outset of the study, it was recognized that informatis
concerning the quality of the concrete, the effectiveness of cong
tion of the dome, and the condition of the material within the s
ture could be obtained only by means of a drilling program. The
Directorate, Fieid Command, DNA, agreed to undertake the drillin
program for the committee.
The report on the results of the dr
{Ristvet 1980) is a comprehensive document that incluces historik
geological, and seismic data.
The drilling started on March 11 and ended on March 28, 1980
much of it took place while committee members were on the site
(}
21-28).
Selection of -he positions of many of the drill holes
in cooperation with + e committee, whose members were able to witmess
the drilling and recovery of cores and to examine the cores as
were extracted.
Detailed descriptions of the cores are supplied[by
Ristvet (1980) but a general summary will be given here.
Twelve sections of the concrete cap were cored with a 4-inch
diamond bit.
Thicknesses varied from 12.5 inches to 24 inches
mean of 17.3 + 3.1 inches.
The concrete was of high quality wi
minor voids or air bubbles.
One cap section showed a l- to 2-in
honeycombed zone with interconnections of voids.
All concrete c
19