Hydrogen accidental formation and ignition at a spent fuel cask of a nuclear power plant

Hydrogen ignition during welding on a VSC-24 spent fuel cask Pursuant to 10 CFR 72.210 - fuel in an independent spent fuel storage installation at its Point Beach Nuclear Power Plant.

The inspection of activities conducted under that general license, found that the weight of the multi-assembly sealed basket (MSB) shield lid was not appropriately translated from the safety analysis report into several procedures and there was an inadequate procedure for placing the MSB transfer cask into the spent fuel pool.
In addition to these findings, it was determined that the use of Carbo Zinc 11 paint, in a borated water environment was not properly assessed by you and your vendor, Sierra Nuclear Corporation. The paint generates hydrogen in a borated water environment and adequate controls to deal with the hydrogen were not provided.

Several opportunities to identify the generation of hydrogen during previous cask loading operations had been missed. Finally, a safety evaluation was not performed for improperly sized rigging utilized for lowering the MSB into the ventilated concrete cask, and a safety evaluation for weighing the MSB shield lid while in place was not adequate.

These violations of the requirements of 10 CFR Part 72 represent a breakdown in control of licensed activities associated with dry cask storage activities and have been classified in the aggregate in accordance with the Enforcement Policy, as a Severity Level III problem.

INITIATING cause of hydrogen generation was the Carbo Zinc 11 paint in a borated water environment paint.
Root cause analysis revealed a lack of risk management.

spent fuel storage installation

Based on various inspections in 1996 , the NRC determined that violations of NRC requirements occurred. The violations are cited in the Notice of Violation and Proposed Imposition of Civil Penalties (Notice) and the circumstances surrounding the violations are described in detail in the subject inspection reports.

Specifically, the penalty for the violation associated with the VSC-24 spent fuel cask is $25,000.

According to the report of the U.S. NRC, the following deficiencies were found:
1. The risk was not properly assessed by you and your vendor, Sierra Nuclear Corporation.
It was determined that the use of Carbo Zinc 11 paint, generates hydrogen in a borated water environment
2. Adequate controls to deal with the hydrogen were not provided.
3. Several opportunities to identify the generation of hydrogen during previous cask loading operations had been missed.
4. Finally, a safety evaluation was not performed for improperly sized rigging utilized for lowering the MSB into the ventilated concrete cask, and a safety evaluation for weighing the MSB shield lid while in place was not adequate.