Page 219 - Challenges in Corrosion Costs Causes Consequences and Control(2015)

NUCLEAR WASTE STORAGE 197

3.31.10 Aircraft
Corrosion has a significant impact on the life-cycle costs of naval aircraft. The navy
has three levels of aircraft maintenance; namely, organizational, intermediate, and
depot maintenance. The organizational maintenance is performed on individual
equipment and includes inspection, servicing, lubrication, adjustments and replace-
ment of parts, assemblies, and subassemblies. The intermediate maintenance is
conducted on parts after removal from equipment and includes calibration repair,
or replacement of damaged or unserviceable parts and components or assemblies.
The depot maintenance involves major overhaul or complete rebuild of parts,
assemblies, subassemblies, and end-items, including the manufacture of parts,
modifications, testing, and reclamation as required. A current estimate for corrosion
maintenance cost is $200,000 per navy aircraft per year (Sedriks, Office of Naval
Research, Personal Communication, July 2000). This cost is nearly twice as much
as the corrosion cost for Air Force aircraft ($100,000 per year) operating under less
corrosive conditions. It is needless to state that naval aircraft operate in significantly
harsher conditions than Air Force aircraft.

3.32 NUCLEAR WASTE STORAGE

Nuclear wastes are generated from spent nuclear fuel from electric power plants,
dismantled weapons, and products such as radio pharmaceuticals. The most important
design item for the safe storage of nuclear waste is the effective shielding of radia-
tion. To minimize the probability of nuclear exposure, special packaging is designed
to meet the protection standards for temporary dry or wet storage or for permanent
underground storage. The most common materials of construction consist of steel and
concrete. The wall thickness of the packaging is generally thick in comparison to the
contained volume.
Corrosion is a form of material degradation that results when moisture or water
comes into contact with the packaging materials. A corrosion failure may not result
in a large release of nuclear waste and radiation; however, a leak would be consid-
ered potentially hazardous and, therefore, would not be acceptable. Currently, nuclear
waste is stored at temporary locations, including water basins in nuclear power plants
and at dry locations aboveground. Deep underground storage in Yucca Mountain,
Nevada, has been proposed as a permanent storage solution.
It is useful to note that when considering the total costs of nuclear material storage,
it is nearly impossible to distinguish the specific corrosion cost, especially for some
corrosion-related costs for nuclear waste packaging design and packaging fabrication
and the costs for remediation of temporary sites that are being used for longer periods
than the time periods for which they were designed.
The great majority of nuclear shipments are very small in size [less than 0.45 kg
(1 lb) per shipment] and total nearly 2.8 million shipments per year (an average of
7656 shipments per day) (51). Spent fuel shipments (material only) typically weigh
0.5–1.0 metric tons for truck shipments and up to 10 metric tons for rail shipments.