Description

DOE-STD-3007-93

channels, 12 inches in width (30.48 cm), through which the monorail system runs. Each channel

is separated by a concrete divider that is 12 inches in width (30.48 cm) and 30 inches high (76.2

cm), as shown in Figure 2.1 The current age of the facility and degradation due to corrosion

problems have led to failures of the monorail fuel storage system, such that the loss of spacing

provided by the monorail system can no longer be considered a contingency.

Fuel is currently stored in the north and middle basins by one of two methods. The first

method, common to most of the navy fuels, consists of fuel hanging from a single hook

arrangement. A standard is placed through the center of the fuel assembly and hung directly on

the hook. In the second method, which is used for the BORAX V fuel, the fuel assemblies are

placed into a bucket that is then hung from the monorail system.

An example of a monorail hanger system and a typical bucket is given in Figure 3.1 The

buckets are constructed of either aluminum or stainless steel, depending upon fuel types stored in

the bucket, thus assuring materials compatibility.

The failure of the monorail storage system is directly related to the corrosion problems in

the north and middle basins. Earlier corrosion problems led to modification of some monorail

hangers. Some of these modifications included the cutting of carbon steel hanger systems and the

replacement of the carbon steel hooks with stainless steel hooks.

In the process of attaching the stainless steel hooks to the carbon steel hanger assemblies,

a galvanic couple was created. With existing corrosion problems and loss of structural integrity

due to the galvanic couple, the load present caused a failure to occur.

Due to the loss of the engineered safety feature (spacing) provided by this system,

evaluation of a new fuel configuration was required. Considered in this evaluation are various

arrangements of BORAX V fuel elements without the spacing that was once maintained by the

monorail storage system. In addition to the loss of spacing between storage buckets, the

reactivity effects due to reflection from the concrete storage channel walls was also evaluated. A

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