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The report also noted no evidence of corrosion of the reinforcement. Significant
corrosion is usually accompanied with spallation and rust staining of the concrete. Neither of
these attributes was observable.
Several other structural assessments have been performed for Corridor C. The structural
assessments confirmed inadequate reinforcing steel was installed in the structure to meet existing
design standards for support of the original and current level of soil overburden. The reduced
margins of safety in the design were then considered along with other pertinent factors. These
factors included the documented forty years of performance, the documented stability of the
identified cracks over four years of record, the (minor) nature of the flexural cracks in the region
of overstress, and the ductile (slow) and observable progression of the predicted failure
mechanism. Significant deformation could be accommodated before collapse would be
imminent., and a monitoring system would give sufficient warning time to take remedial action if
further distress of the corridor were to occur. These considerations supported a position that
catastrophic failure was not imminent from a structural view, and that it was reasonable to
continue operations, with compensatory actions, until a safe and orderly restoration of safe
material storage conditions could be accomplished. One recommended compensatory action,
installing a crack monitoring system (strain gages), was implemented to provide indication of
further degradation of the corridor. Other compensatory actions such as removing the soil
overburden, posting the area to prevent increases in overburden loads, sealing of actively leaking
cracks by sealant injection, and re-constructive repair of major cracks have not been
implemented.
Based upon the evaluatio& performed, and the costs associated with repairing the tunnel
to meet acceptable structural criteria, storage of radioactive waste is currently prohibited in
Corridor C. This prohibition is reflected in Appendix A, Building 991 Complex Technical Safety
Requirements, Administrative Control (AC) 5.2.
2.2.5 Buildings 997 and 999
Building 997 is an underground vault structure located northwest of Building 991. The
building was built to withstand exceptionally high blast pressures. The exterior walls are 14 feet
6 inch thick reinforced concrete. The roof is 12 feet thick concrete with one to 10 feet of earth
covering. The floors are six feet thick concrete and the interior partitions are two feet thick
concrete. The outside dimensions of the building are 60 feet by 68 feet. The building has four
main storage areas, which are 12 feet wide by 18 feet 6 inches long by 10 feet high. The
original design criteria of Building 997 required the structure to support specific dead loads and
to withstand the blast pressure of a semi-annor piercing 2,000 pound bomb (1,000 pounds per
square foot blast pressure and 18.7 inches diameter, 1,100 feet per second inert penetration). For
Building 997 this criteria included a direct-hit penetration resistance (Ref. 1 and 14).
Building 997 is a massive structure and a structural evaluation performed in 1979 indicated that
the structural components are capable of withstanding the seismic loads from a design basis
earthquake @BE). The building, being underground, is not subject to tornado or wind loading,
or impact from tomado-driven missiles (Ref. 15 and 16).
Revision 1 2-13 Building 99 1 Complex FSAR
Scpfcrnher 1939
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