nuclear power

Case Study - Nuclear Power Plant Fire

nuclear power plant fire protection

When a nuclear power plant had a transformer fire that stopped the presses, they called F.E. Moran Special Hazard Systems to get them back online quickly.

Writer: Sarah Block, Marketing Director of The Moran Group

 

A Forced Outage Causes a Media Stir

 

In Eastern New York, an alarm blared on May 9, 2015.  A voice came over a loud speaker, “This is not a drill.  This is not a drill.”  Smoke poured from a GSU transformer that had failed and caught fire.  The fire sprinklers activated and extinguished the fire.  However, smoke was already pouring from the transformer that was no longer usable, causing a forced outage. 

A forced outage is when equipment is unavailable because of an unanticipated breakdown and an outage can’t be avoided beyond 48 hours.  If there are numerous forced outages in a year, the Nuclear Regulatory Commission (NRC) can change a nuclear plant’s ranking.  It was imperative that the plant got back online quickly.  They hired a well-known technology producer to replace the transformer.  This producer hired F.E. Moran Special Hazard Systems to protect the new transformer with custom fire sprinklers.   

 

Fast-paced with Quick Pivots

 

From the moment F.E. Moran Special Hazard Systems got the call, it was an all hands on deck project. They got the call on a Friday morning.  The plant needed people that day to start planning, and, on top of the short notice, they needed a 10-man crew on site around the clock with a superintendent and foreman.

While this was going on, the design team had their own set of obstacles.  The plant had a spare transformer and a generic fire sprinkler design in place.  The lead designer for Moran on the project had to re-design the existing layout to accommodate the new transformer.

A last minute decision to add the alarm installation to the project increased the pressure on the already intense project.  An F.E. Moran Special Hazard Systems Alarm System Designer began work immediately on designing the detection and notification portion of the project.

Each of the designs needed to be completed, submitted to the owner, and approved quickly to support the installation.  A few impediments got in the way.  One, the isophase bus-duct design caused an adjustment with piping that wasn’t in the original design.  To incorporate these changes, extra materials needed to be procured but they were not readily available.  The technology producer, fabricator, and plant owner could not get the additional materials needed.  But through Moran’s national network of contacts, the extra material was found and delivered within hours.

The Stars Align

F.E. Moran Special Hazard Systems got the call in the morning, needed to man the job by that afternoon, and develop a design even as the installation crew commenced planning and layout. With the Moran Superintendent on site by Friday afternoon, his first requirement was manpower.  A ten-man crew needed to be on site day and night for the duration.  The Sprinkler Fitters Local Union 669 had four people available in the immediate area, and got them on site quickly. The Moran Project Manager, contacted the Local 669 Assistant Business Manager on Saturday night to assist him in finding the other six.  With Local 669’s help, we were able to find the rest of the men and get them on site the next day along with Moran’s Night Superintendent.

While that was taking place, the design team was working hard to get the designs completed and approved.  At 2am on Monday, a team from Moran arrived in New York.  By 4am, they were on site and being debriefed.  They worked with the technology producer and plant to get the final design approved.  From there, they began staging materials and planning the work. 

With the fast pace, the project could have gone off track quickly.  But due to an experienced and knowledgeable team, everything aligned and the project went off without a hitch. Any problems were solved quickly without delays to the final completion.  We were able to man the job, redesign the system, install it, start it up, and as-build the drawings while exceeding the clients’ expectations and solving the fire protection problem.

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Best Practices for Implementing Effective Fire Suppression Systems for Transformers in Nuclear Plant

transformer fire protection

As one of the most watched-over industries in the world, nuclear power generating plants are required to abide by an abundance of regulations and standards to ensure that the facility, its employees, the environment and the local population are protected from potential hazards. One of the most ominous threats that every nuclear power generating facility faces is the risk of a fire developing within the plant and the associated consequences. There is no shortage of hazards within these facilities; the possibility for fires to ignite from sources such as lube oil, fuel oil or general combustibles within a warehouse are genuine concerns. However, one of the most common sources for ignition - and unfortunately one of the most dangerous as well - are the plant's transformers.

 

How Do Transformer Fires Ignite?

 

It is no surprise that transformers are inherently high-risk, considering the hundreds of thousands of volts that they transfer on a continuous basis. There are a number of events that can trigger transformer fires, from weather-related incidents to failures stemming from equipment operating beyond its intended service life . While lightning and short circuits in electrical equipment can cause transformer failures, breakdowns in the insulation system are frequently found to be the source of failure. As the insulation material protecting the transformer deteriorates over time from exposure to natural elements, it puts the equipment at risk for failure and subsequently, fires.

 

What Are the Implications of a Transformer Fire?

 

Depending on the severity of the fire and the effectiveness of the fire suppression system protecting the area, the consequences of a transformer fire can range from minimal to devastating. Ensuing damage can include the destruction of overhead conducters, buses and cable trays, as well as the potential for more extreme ramifications when oil or other flammable materials are introduced.

It is not uncommon for a transformer to rupture during a failure, which can release oil into the area, amplifying the risk substantially. When oil is emitted from the transformer, it has the potential to spread the fire to other areas of the facility, resulting in broader damage. Additionally, if the water discharge calculations are incorrect or the containment pits are not the appropriate size, it is possible for oil to overflow from the collection basins. This creates environmental concerns and can result in oil infiltrating the water source that is used to deliver water to the fire suppression system, impeding the system's ability to control the fire. It is critical that all of these variables are taken into account when implementing a fire protection system to minimize the risks associated with transformer fires.

 

What Design Tactics Must be Used to Develop an Effective Fire Protection System for Transformers?

 

Stringent regulations require fire protection system designers to follow very rigid guidelines when designing a suppression system for transformers. However, integrating these guidelines into the unique environment of an individual plant can be laborious and demands a great deal of expertise. Optimizing the design for the most effective protection, while also adhering to the requirements set forth by the Authority Having Jurisdiction (AHJ), NFPA, insurance requirements and nuclear authorities demands direct knowledge of and experience with the application.

Effective design should begin by utilizing the transformer outline drawings to develop a system that will function within the parameters ascertained from the drawings. It is at this stage that a designer can determine the most efficient piping system to optimize water discharge through the strategic placement of nozzles. Selecting the appropriate nozzle for the application requires sufficient knowledge to make a determination about which nozzle angle and orifice size will be the most effective for the particular design. Nozzles should be positioned to provide complete water spray impingement on all exterior surfaces without directly enveloping energized bushings or lightning arrestors. Additional considerations such as electrical clearance requirements and future access to coolers and control cabinets should be factored into the design as well, for simplified plant maintenance of the transformer in the future.  Designing a deluge releasing system should also involve the same level of forethought to ensure that all potential issues are considered before they impede the effectiveness of the fire protection system or cause a hindrance to plant operations.

 

Exhaustive Pre-Planning, Efficient Installation Practices Allow for Streamlined Work

 

Beyond the expertise that is required to design an effective fire protection system for a transformer in a nuclear application, it is essential that comprehensive pre-planning is conducted before the installation begins. Plant outages are typically brief, giving the installation crew a very limited timeframe to install the system and perform the appropriate testing. The background work related to access, safety, quality control and material management must be thoroughly arranged to allow for an efficient installation.

Extensive collaboration between Project Mangers and Plant Engineering should occur on an ongoing basis to identify pre-outage work and ensure that all parties' expectations are aligned. The contractor and owner should work closely to develop an engineering change package that reflects any and all of the nuances associated with transformer fire protection and the specific environmental factors of the site. Facets of the project such as determining the location of pipe foundations to suit the transformer foot print and calculating the water discharge in relationship to the size of the containment pits should be addressed comprehensively to minimize any delays that could occur once the outage has begun.

Material management and safety requirements can also present challenges if certain measures are not taken to streamline the process. A detailed pre-fabricated material and parts list can help alleviate logistical issues by making it easier to track materials, meet Foreign Material Exclusion (FME) requirements and control quality assurance. The contractor should have a thorough understanding of the material receipt and related processes to avoid unnecessary interruptions in the installation process. To ensure efficiency, those involved in the installation should complete any safety requirements well before the on-site work begins and a job safety analysis should be conducted to prevent injury during the installation.

Once the on-site work has begun, it is imperative that installation crews adhere to the strategy that has been mapped out in the pre-planning stage of the project. Efficient management of equipment such as aerial lifts and scaffolding saves time and improves workflow. Coordination with other trades performing work on the site is vital to maximizing manpower as well as ensuring the safety of the crew. Transformer areas are inherently congested, leaving little room for installers to perform their work. Installers should have the skill and experience that is required to perform intricate work within tight spaces that present obstructions.

 

Effective Transformer Fire Protection is More than Just Exemplary Design and Installation

 

As crucial as competent design and installation methodologies are to the performance of a transformer's fire protection system, the long-term performance of the system relies on ongoing inspection, testing and maintenance (ITM). Developing a comprehensive ITM regimen, which includes detailed documentation of the processes performed, is imperative to ensuring the system will function as intended when it is called upon.

As previously stated, the potential repercussions of an uncontrolled transformer fire can be devastating to a nuclear power plant. For this reason, it is equally important for a fire protection system to be as robust in the years following implementation as it was when it was first implemented. Just as NFPA, insurance and the AHJ requirements dictated the design and installation guidelines for design and installation; an ITM program should be cultivated in accordance with these regulations as well.

Weekly and monthly inspections of specific components, annual trip tests and full flow tests at prescribed intervals can ensure that systems will be fully functional when activated. Other maintenance processes such as draining the oil collection basins after heavy rains can also prevent problems specific to transformers. In nuclear applications, discovering that a fire protection system is not functioning at peak performance after a fire has ignited is too late.

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Fukushima: Before, During, & After the Tsunami

Fukushima

The earthquake, subsequent tsunami, and nuclear power plant disaster in Fukushima, Japan is seared into our memories ever since March 11, 2011. The tsunami that caused the nuclear power plant disaster killed 19,000 people in one fell swoop. At the same time, the tsunami swept away the emergency diesel generators that are used to cool the nuclear power plant reactors in case of power failure. This allowed for a complete nuclear meltdown. It was the perfect recipe for disaster.
 

Firsthand account from Carl Pilitteri, Excerpt from Environmental Action:

"In one nanosecond, the entire floor went black. Every light went out. You would expect some emergency lighting would come on, but there wasn't a one. And there was this most welcome beam of light coming from the gap under the door. I made my way over to the door, and the one and only light in the room, it was swinging violently and then at the same time I opened the door it busted free and shattered on the floor. It was pitch black again. I remember thinking, ‘None of you are getting out of here.'

One of the Japanese guys had grabbed me around the waist. I put my arm up on his shoulder. With every jolt I squeezed his shoulder. I remember praying aloud for him, for all of us. I thought, we're going to perish in this turbine building. I can still hear the turbine making its unwelcome sound. I had many thoughts. But one of them was: Good God. I got up this morning just to go to work. And this is how it's written for me? Dying is a fact of life. We all have to do it sooner or later. But this is how it's written for me? March 11? On a Friday? On a turbine deck? In Fukushima? At work? Of course my thoughts went immediately to my family. My two young children."

Before the Tsunami

 

Researchers are now saying that the nuclear power plant disaster was bound to happen eventually, based on plant designs. USC Viterbi School of

 Engineering and the Middle East Technical University have gone through government, industrial, and media reports to figure out why the power plant disaster happened. Through their research, they found that design flaws, regulatory failures, and improper hazard reports are the reason that the disaster happened in the first place.

"Earlier, government and industrial studies focused on the mechanical failures and ‘buried the lead.' The pre-event tsunami hazards study, if done properly, would have identified the diesel generators as the lynch pin of a future disaster. Fukushima dai-ichi was a sitting duck waiting to be flooded," said Professor Synolakis of Civil and Environmental Engineering at USC Vitebi.

The research paper states that the nuclear disaster was a "cascade of industrial, regulatory, and engineering failures" that led to the backup generators (needed to cool the plant in the event of power failure) being built in harm's way. The generators were built in the wrong spot.

"What doomed Fukushima dai-ichi was the elevation of the EDGs," the paper states. They were too low. One set was in the basement and the others were only 10-13 meters above sea level. It was later confirmed that the builders of the plant ignored Japanese scientists who said that larger tsunamis were possible and the EDGs should be placed higher. This is proven by the fact that 22 of the 33 backup generators were washed away by the tsunami, allowing for the meltdown.

 

During the Tsunami

On March 11, 2011, an earthquake prompted a tsunami that caused devastating, far-reaching effects for the world. At 2:46pm a magnitude 9 earthquake hit, which caused the tsunami. The largest wave arrived 50 minutes after the earthquake and reached 13 meters tall, overwhelming the power plant's seawall, which was 10 meters tall. Water flooded the low-lying rooms where the EDGs were housed.

 

The tsunami swept away 22 of the 33 backup generators, used to cool the nuclear reactors in the event of a power failure. This caused all three cores to melt within three days. The accident was rated a 7 (the same as Chernobyl) on the INES scale because of the high radioactivity. It released 940 PBq of radiation over 4-6 days.

Four reactors were written off. It took two weeks to begin to stabilize the other three reactors with water. By July, they were cooled by recycled water. By mid-December, a "cold shutdown condition" was announced.

After the Tsunami

Following the tsunami and nuclear power plant disaster, 100,000 people were evacuated to avoid the nuclear fallout. Japan began screening children that lived near the evacuation zone for thyroid cancer in 2012. As of December, 2014, 112 cases have been found. Stanford University predicts that within 10 years, there will be 130 fatalities and 180 additional cases of cancer related to the radiation.
The area around the nuclear power plant still has dangerous levels of radiation. Hundreds of fuel rods are still there, unable to be moved because they are unstable. This is also causing the underground water to be contaminated.

In response to this disaster, many countries have gone against nuclear power. Within days of the Fukushima disaster, Germany had already shut down 8 of their 17 nuclear power plants. Other countries planned to do the same. However, now it appears that this reaction was based on false information. If the reason for the disaster was the faulty design, then the risk for a similar accident can be avoided by simply designing the plant correctly.

The Fukushima nuclear power plant disaster forever changed not only Japan, but the world. It is an example of what can happen when power plant design takes a shortcut. The design of all things related to something as powerful, yet fragile as a power plant need to be meticulous. The results of not making proper design a priority are shown here. The world doesn't need another nuclear disaster. Chernobyl and Fukushima showcased it well enough.


Resources:


http://environmental-action.org/blog/fukushima-first-hand-account/

http://fukushimaupdate.com/the-fukushima-disaster-was-preventable/

https://www.washingtonpost.com/news/worldviews/wp/2015/03/12/3-ways-the-fukushima-nuclear-disaster-is-still-having-an-impact-today/

https://en.wikipedia.org/wiki/Fukushima_Daiichi_nuclear_disaster

http://fukushimaontheglobe.com/resource-library/stories-and-facts-from-fukushima

http://www.world-nuclear.org/info/Safety-and-Security/Safety-of-Plants/Fukushima-Accident/

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