Outages and Operations
From Tip of the Week, 23 March 2019 — written after getting home. Now that I’m back from the outage, it’s time to get back to normal…
After my last email, a friend wrote to me about outages and the important role that Operations plays. I wanted to share his insights with you and my own commentary in between:
From breaker open to 100% power, Operations performs numerous surveillances, equipment checks, and shutdown procedures. Operations also plays a key role in work control. They maintain the nuclear worker’s safety by ensuring equipment is safe to work on and free of stored energy or electricity.
Operations is generally in charge of the tagging process. My friend is correct: if Ops makes a mistake when developing tagging boundaries for a particular scope of work, then they could put the workers at risk.
They bear a lot of responsibility for maintaining electrical safety, and every Operator I have ever talked to who was in charge of developing tagging boundaries was conscientious of his role and took his job very seriously.
But this doesn’t free individual workers from their own personal responsibility. They must follow standard work procedures to make sure their work areas are safe and de-energized as expected. Engineers must also be diligent about signing on to tagouts and observing safe electrical clearances.
It is often thought that because it’s an outage, we should be able to work on anything at anytime. However, many fail to realize that during some modes of operation, there is a core full of fuel to stabilize–and sometimes at a lowered reactor coolant system inventory. This means there are still protected power trains, safeguarded equipment, and essential areas to maintain even more so than at 100% power. Operations is our primary defense mechanism for ensuring nuclear safety during outages.
One component of each of our daily turnover meetings was a quick reactor status update and systems safety assessment. I was at a BWR plant, where outage risk is greater near the beginning, as explained by the NRC in Information Notice 2000-13:
In general, the refueling activities associated with a BWR are more time-intensive and full core offloads are not generally performed. Thus, the risk of in-vessel core damage remains throughout the outage. The risk profile associated with the BWR outage shows an inverse relationship with respect to inventory levels and decreases gradually throughout the outage due to dissipating decay heat levels.
This is why workers and engineers have to pay attention to barriers around equipment on protected trains: accidental bumps and equipment trips are intolerable. This is especially true if one of the two safety trains has been taken out of service to support work or maintenance activities. Operators are especially tuned to these issues, and so everyone should be in order to support the overall goal of doing high-quality work without jeopardizing nuclear safety.
On how adverse human performance events have impacted outage risk, see Information Notice 2005-16.
Lastly, and my favorite: Operations is responsible for getting the unit back to full power. This is a little more involved for a PWR versus and BWR, but for the naturally inquisitive among us, it is something to appreciate in either case. Sustaining a nuclear reaction, heating up the secondary, drawing vacuum in the condenser, speeding up the turbine to 1800 RPM, synchronizing the generator with the grid, and watching power escalate to 100% makes the reason you came to work the outage all worth it.
Indeed.