Primary coolant water is monitored continuously for fission product species so that any leak is quickly detected. Depending on severity:
| Severity | Operational Response |
|---|---|
| Very minor leak | No change to operations. The faulty fuel assembly is removed at the next refuelling, inspected, and possibly re-loaded. |
| Small leak | Allowable thermal transients are restricted (may prevent load-following mode). Careful monitoring required. Faulty assembly generally removed at next scheduled refuelling. |
| Significant leak | The reactor is shut down and the faulty assembly located and removed. |