During an external review of the facility safety basis document, it was identified that the accident analysis for the pool cell area hydrogen explosion did not account for release of stored hydrogen from the pool cell water as the temperature of the water increases. The analysis only accounted for the hydrogen generated by radiolysis. A loss of pool cell cooling occurring concurrently with a loss of ventilation would result in a higher concentration of hydrogen in the pool cell area than calculated in the safety basis. The safety basis document is being revised to account for the increase in hydrogen concentration.
Process changes have been implemented for development and review of safety basis documents that focus on a collaborative effort between the preparer and reviewers in order to provide a more in-depth review. This change is anticipated to provide new perspectives that may compensate for human error.