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Nuclear Fuel Storage Container Crack/Corrosion Sensor (NFSCCS)

Photograph of spent nuclear fuel canisters.

Spent nuclear fuel canisters.

A significant portion of the Unites States’ annual energy demand is provided by nuclear power. Safe storage of spent nuclear fuel is an essential part of the fuel life-cycle. Currently, spent fuel is typically stored at the reactor site in stainless-steel canisters that are welded shut and back-filled with helium.

Image of a NSF canister cutout.

Breakdown of a NSF canister.

Since the storage containers are passively cooled with air from the ambient environment, the canisters may become susceptible to atmospheric induced corrosion damage, particularly in the weld sensitized region. To ensure the integrity of the storage containers, and ensure that prolonged safe-storage is maintained, it is desired to develop a sensor which monitors the possible presence and extent of corrosion damage. Towards this end, we have designed a miniature test apparatus to mimic the conditions in which stress corrosion cracking is likely to occur.

These fixtures use a three point bend test configuration to stress stainless steel samples while collecting resistance measurements over time. Sample failure is signaled by a sudden increase in resistance across the sample. An array of these fixtures, loaded with sacrificial electrodes, are incorporated into the full sensor package. The sacrificial electrodes may be tailored to match the intended material and allow for multiple conditions to be simultaneously monitored. In this manner, the impact of detrimental conditions such as weld sensitization or the presence of residual stress on the corrosion behavior, may be in the sacrificial electrodes and specifically sensed. A corrosion rate or crack propagation rate may also be inferred by sensing failure on progressively larger electrodes. This sensor design can be easily adapted to match a specific metal and allows for multiple corrosion processes to be simultaneously detected.

Image of a rendering for the complete sensor.

Model of the complete sensor.

 

Research supported by:

Image of SCC Project collaborators. Image of the CAES logo.