What does the “open phase condition” petition mean for US nuclear plants?

On March 1, 2016, Reuters published an article titled U.S. NRC engineers urge fix for nuclear power stations. Here is how the article seized my attention.

A group of engineers within the U.S. nuclear power regulator is concerned that a design flaw in nearly all U.S. nuclear plants could endanger emergency core cooling systems. The group has urged the regulator to order power station operators to either fix the problem or face mandatory shutdowns.

Seven engineers in late February petitioned the Nuclear Regulatory Commission to order immediate enforcement actions against licensees of U.S. nuclear power plants, in a little-noticed, but public move.

The same article caught the attention of several loyal readers whose quickly recognized the implication of a “design flaw” affecting all U.S. nuclear plants, especially one that had been judged by some NRC engineers to be so serious that they were considering mandatory shutdowns of unknown duration.

This is going to be a fairly lengthy and technical article, so I want to start with the most important information first.

Bottom line up front

I just finished talking with Roy Mathew, the NRC engineer whose name is at the top of the list of the seven signatories of the petition filed with the NRC in late February. I’d had a short conversation with one of the other members of the group on Friday afternoon; he confirmed that Mathew is the leader of the initiative and asked me to contact him on Monday morning after he returned from business-related travel.

Mr. Mathew assured me that he and his colleagues are not suggesting that U.S. nuclear plants should be shut down. Though they included that as one of the possible alternative actions in their petition, they did not think that anyone would want that to happen when there are other less impactful actions that could solve the problem.

The condition that concerns them is one that has been recognized and understood for several years, there is an industry-led action underway for a permanent correction, there are effective compensatory actions being done, the public has been kept informed and the commission staff has been involved since the beginning.

The reason that he and his colleagues have taken the process step of filing a public petition under section 2.206 seeking action by the Commission is that they are frustrated by what they view as a bogged down process of issuing formal orders to the industry confirming that the NRC agrees with the actions that they are already taking.

Draft orders–in the form of a Commission Paper (SECY)–were available well over a year ago. During a public meeting held in February 2015, the NRC indicated that the draft paper would be issued by March 2015. Since that paper had not yet been issued and there did not appear to be any schedule for it to be issued as of February 2016, the group of engineers determined they needed to take a step that would stimulate action within a certain period of time.

The normal timeline for a 2.206 petition that asks for near term action is to provide a response identifying the process that would be undertaken within 30 days. Mr. Mathew indicated that he and his fellow petitioners recognize that a significant contributor to the slow review process for this petition is the fact that there has been a major organizational change and a number of management shifts in the agency over the past couple of years.

With an issue that is as technical as the “open phase condition”, it can take even technically oriented and qualified managers some time to study the full implications before they are ready to make a responsible decision on a complex course of actions.

No worries of retaliation

I’m pretty sure that a large fraction of the people who read Atomic Insights have, at one time or another in their professional careers, been involved in large, slow-moving, multilevel, and multi-branched bureaucratic organizations. Having been a staff-level person myself (aka a cog in the machine) it can sometimes feel like you are pushing a rope or trying to move a very large blob through a maze.

Your bosses might be sympathetic or not, engaged or distracted, harried or relaxed, but for whatever reason, it can seem like their priority is not your priority. If you are lucky, however, you work in an organization with well established processes that enable even low level people to capture attention and change priorities if they have a solid concern.

The NRC is one of those organizations; its people and management are inculcated with a strong culture that allows people with legitimate concerns to raise them both within the agency and in public when necessary without any fear of retaliation or repercussions. Mr. Mathew and his colleagues will most likely be congratulated on their persistence and initiative in reminding their chain of command that they need to complete the actions that were ready to complete last year.

Public Affairs Office Response

When I first read the Reuters article, I contacted the NRC public affairs office to get a sense for the urgency of my own investigation. I needed to know if there was time for me to come up to speed on the issue before feeling the need to write something to give you a heads up.

Here is the response I received from Scott Burnell on March 3.

HI Rod;

Here’s a little more detail on why the NRC remains satisfied U.S. plants can operate safely while this issue is resolved:

Plants where the “open phase” issue happened all shut down safely despite the condition.
U.S. plants have put additional measures and procedures in place to prevent or swiftly deal with the condition.

The agency also continues to examine potential additional regulatory action on the issue.

The NRC is handling this petition in exactly the same manner as all others of its kind; while the petitioners are NRC staff, they’ve filed the paperwork using a process available to any member of the public. This petition includes a request for immediate action, which the agency always aims to decide on within 30 days. The overall petition request will take longer to process.

The petition is available in ADAMS:


That gave me the assurance that I had some time.

Open Phase Condition (OPC)

On January 30, 2012, Exelon’s Byron Station Unit 2 suffered a mechanical failure of a porcelain insulator supporting one phase of the 345 kV feeder from off site. That opened the circuit for that single phase, but due to the way that the the voltage detection system was designed, there was no fault signal generated.

However, the open phase resulted in an undervoltage condition on the 6.9 KV buses supplying power for two of the four operating reactor coolant pumps. The UV trips generated an automatic trip (scram) of the reactor about a second after the open phase condition occurred.

Later changes in the electric supply line-up resulted in a number of motor trips, which added some complications to the plant shutdown.

On February 28, 2012, Byron Station Unit 1 suffered a similar mechanical failure of a porcelain insulator supporting one phase of the 345 kV feeder. That failure was detected and did not result in a motor trips or a reactor trip.

Exelon’s investigations of the failures are summarized in a brief presented to the NRC in March 2012.

For the really technically astute and interested members of the Atomic Insights audience, I can recommend two posts on reddit by a contributor with the pseudonym of “hiddencamper.” I have checked with several confirmatory sources; his explanations are both readable and accurate. Open Phase issue Post 1 and Open Phase Issue Post 2

A complete discussion of the actions and meetings that have transpired since that presentation is way beyond the scope of this article; suffice it to say that the issue has been aggressively addressed.

NEI’s Open Phase Condition Point Man

After several rounds of phone tag exacerbated by the fact that annual NRC Regulatory Information Conference (RIC) was held last week, I managed to get connected with Steve Hutchins, who is on loan from Exelon Generation to the Nuclear Energy Institute as a senior project manager. One of his primary duties is leading the industry response to the open phase vulnerability.

Hutchins was the senior manager electrical engineering for Exelon Generation corporate when he was sent to the Byron site on January 31, 2012 to learn more about the open phase event that had occurred at Unit 2. He’s been deeply involved with the condition ever since. When he tried to retire Exelon asked him to go to NEI to lead the industry’s response effort. He’s currently schedule to complete his assignment in May 2017.

Hutchins is a self described passionate engineer who apologized for speaking fast. Fortunately, was recording our conversation and have been able to replay it several times.

Here are my key take-aways from our conversation.

  • The condition does not affect every plant. There are a few, like the Seabrook plant, whose off site power source configuration essentially eliminate any vulnerability.
  • All of the affected plants have implemented compensatory actions that ensure safe operations even under “design basis events.”
  • Five different groups have developed five different modifications that will work for different segments of the fleet.
  • The number of units on site plays a big role in the specifics of the vulnerability.
  • Thirty of the 100 operating units have completed the necessary modifications to ensure that their electrical supply protective sensors will detect an open phase condition and provide a proper response without excessive false positives.
  • All of the modifications will be completed before the end of 2018.
  • A large majority will be completed by the end of the second quarter of 2017. Some of the later to be corrected have complicated phasing in relation to other scheduled outage work.
  • Oconee’s event was a validation that the compensatory actions are working, not an indication that they are not working.
  • The industry is ready to received the SECY orders and any notice of discretionary enforcement that might be associated with those orders.

Despite the portrayals of this issue in the predictably negative antinuclear press, the public is being adequately protected. The NRC processes have been bogged down, for whatever reason, but that has not stopped the industry from making progress. It has also not gone unnoticed by the dedicated individual NRC engineers who have taken advantage of the processes provided to draw increased attention to a challenging technical issue.

Their request will encourage the processes to move a bit more rapidly and the paperwork to achieve a more completed status.

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