NRC accepts open phase petition, declines immediate action request

This is the continuation of an earlier story regarding electrical issues at Bryon and other nuclear power plants.  SEE the following posting regarding the issues:  http://boonecountywatchdog.blogspot.com/2016/03/dangerous-flaw-discovered-at-byron.html

NRC accepts open phase petition, declines immediate action request

BY   Adam Smith

The U.S. Nuclear Regulator Commission recently agreed to accept a petition submitted by seven engineers with the U.S. Nuclear Regulatory Commission who expressed concern over a power distribution issue at nuclear power plants.
The petition was filed on Feb. 19, and the NRC issued a response to the petition on March 21. The engineers had sought an immediate resolution to an open phase electrical issue they felt made nuclear plants vulnerable. If the issue could not be resolved immediately, the petition asked the NRC to shutter all U.S. nuclear plants.
Five of the engineers who submitted the petition are from Maryland, while one is from Louisiana and another from West Virginia.

While the petition was accepted for review, a summary on the NRC's website said, “the immediate actions requested by the petitioners were denied because of the risk reduction provided by the interim compensatory measures.” The NRC's response noted two invitations to the petitioners to address the Petition Review Board, which was declined on the grounds the “petition already contained all of the relevant information to support the PRB’s review.”
The notice to the petitioners said the NRC would take action on the request “within a reasonable amount of time,” though no timeline was provided.
“The resolution of the petitioners' concerns will be tied into the ultimate resolution of the issue,” said Scott Burnell, spokesman for the NRC.
About the issue
The petition was filed over concern about an open-phase condition that occurred at Exelon’s Byron 2 Nuclear Station in Illinois in 2012. Power to large industrial facilities, like nuclear power plants, is delivered in three phases. In this case, one of the phases dropped out in the plant's switchyard, which impacted how electrical current was being distributed throughout the plant.
In this situation, the plant's automatic systems did not recognize a phase had dropped out, and operators didn't immediately realize it. During that time, the plant's reactor safety systems did not operate as effectively as they could have. Once the problem was discovered, the power was rerouted accordingly and the plant was shut down safely.
“The Byron event identified a vulnerability in the design of U.S. and international, operating plants. The current design requires an accident signal to automatically connect the emergency core cooling systems to the preferred power source to mitigate the consequences of a design-basis event,” says the petition. “... If the preferred power source, has an undetected open phase-condition, redundant trains of electrical equipment (electric motors that drive the pumps and valves) could burn out in few minutes and therefore will not be available for safe shutdown, even after restoration of an operable power source.”

A design-basis event, or accident, is defined by the NRC as a “postulated accident that a nuclear facility must be designed and built to withstand without loss to the systems, structures, and components necessary to ensure public health and safety.”
Burnell previously told The News Courier the incident led the NRC to examine the issue more closely, and a bulletin was issued to all nuclear power plants, including Browns Ferry Nuclear Plant in Athens, explaining the open-phase incident. The bulletin also requested information from the operators explaining how they would handle the issue if it occurred at their plants.
Moving forward
According to the NRC, nuclear power plant operators are currently implementing the permanent solution for the open phase issue. Those changes should be implemented by Jan. 30, 2019, but may need NRC approval via license amendment.
“Either way, the NRC staff plans to … confirm that regulatory requirements are met,” says information on the NRC's website.
When asked about the process of implementing the changes at Browns Ferry Nuclear Plant, Tennessee Valley Authority Spokesman Jim Hopson issued the following statement: “TVA is committed to ensuring the safety of the public as they continue to benefit from the reliable, low-cost, carbon-free power nuclear generation provides.We are closely following the NRC’s inquiry into this issue and, based on their guidance, will take the steps necessary to further enhance the safe design of our nuclear facilities.”

Above is from:  http://www.enewscourier.com/news/local_news/nrc-accepts-open-phase-petition-declines-immediate-action-request/article_929c67b4-f866-11e5-9d93-072b2433e8fe.html