High Burnup Nuclear Fuel Pushing the Safety Envelope via San Onofre Safety

As commercial reactor economics have declined, utilities, with the acquiescence of the Nuclear Regulatory Commission (NRC), have burned nuclear fuel longer and crammed more of it into storage containers. This experiment has unresolved serious safety issues for storage, transportation and disposal of this highly radioactive waste; issues that have been essentially overlooked by nuclear regulators and the general public.

For high burnup fuel (HBF), the cladding surrounding nuclear fuel, is thinner, more brittle, with additional cracks. In a transportation accident, the cladding could shatter and a large inventory of radioactivity, particularly cesium, could be released. The NRC should stop use of HBF and make solving HBF storage problems one of its highest priorities.
The only issue NRC staff consider is the highest heat within a storage cask, but this ignores the fact that the cladding of HBF is thinner, more brittle, with additional cracks, as shown in Fig. 1. Longer cooling time will not solve these problems.

Uranium fuel pellets, stacked within long thin tubes called cladding, are struck by neutrons and fission, producing heat. A collection of these tubes is called a nuclear fuel assembly, shown in Fig. 2. After 3 to 4 years, extremely radioactive and thermally hot fuel assemblies are removed from the reactor and stored underwater in a fuel pool. Following a cooling period of 7 to 20 years, 24 to 32 fuel assemblies are removed from the fuel pool and inserted into a fuel canister, which are then pushed into a concrete overpack shown in Fig. 3. Because of the poor economics of nuclear power, utilities are pushing the limits for how long fuel remains in reactors with dire consequences.

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