Expert article

What to consider when modernizing nuclear lifting equipment

Polar crane trolley

As today’s power industry grapples with the pressing need to extend the life of its operating nuclear plants, managers are learning that few elements of the plant infrastructure offer more opportunity for renewal than its cranes.

 

Jay Edmundson, P.E., P.Eng., Vice President of Engineering, Konecranes Nuclear Equipment & Services LLC

 

The nuclear power industry in the United States dates back to the late 1970s and early 1980s. By 2020, there were 92 working nuclear power plants in the U.S., with most operating for more than their initial 40-year license. Because of the massive potential consequences of a failure, cranes that handle nuclear material are required to include additional safety systems including single-failure-proof, pushing reliability to extreme levels. Those outside the industry may wonder, how is this feasible, operating with 40-year-old equipment?  

Like many cranes of this era, the workhorse polar, reactor and fuel handling cranes in older nuclear power plants were over-engineered in a major way. Because they are mainly used during outages, even today these cranes still offer decades of useful life in their structural components. However, other critical parts are fast reaching the end of their economic service life. Obsolescence of early-era electrical controls is an enormous problem for plant managers, with unavailable parts and a shortage of craftsmen familiar with the aging equipment topping the list of issues. So today’s crane modernization experts must walk a fine line between optimizing equipment life and maintaining the levels of extreme reliability expected in a nuclear power plant. 

 

Squeezing more out of less

With power needs increasing and the construction of new nuclear plants extremely expensive, current industry thinking is that existing nuclear plants need to remain in operation for at least 60 years. Crane modernization is a realistic avenue to extend equipment life while complying with stringent and evolving safety regulations.

Plant managers are also facing increasing production demands: when electrical turbines aren’t turning, plants aren’t making money. Downtime is costly, so planned maintenance outages when modernization can occur are often shorter than they used to be. A typical outage occurs every 18 months, lasting approximately 21 to 28 days. Whatever a professional modernization team can do to get the plant back on line within the expected time frame can save their customer $1.5 to $2.5 million per day

 

Where opportunity lies

The key players in any nuclear crane modernization scenario are the polar crane and the fuel handlingequipment, both located near the reactor which designates highest-risk activity.

The polar crane or reactor crane is used for removal and replacement of the reactor head and upper components of the reactor. Moving on a circular or straight track runway, it also lifts and moves all components in and out of the containment building, so it is the workhorse of the outage. It has both a main and an auxiliary hoist, which perform typical plant maintenance and operational functions. The cranes may also have a maintenance jib crane for maintaining the crane itself, and/or a containment inspection man lift used for inspecting and maintaining the containment dome.

All of these lifting systems can benefit from increased reliability and productivity by upgrading the control system using AC variable frequency drives or other commercially available control systems. This upgrade eliminates the parts sourcing and labor problems associated with the original outdated controls and makes crane operation more cost-effective for the plant. In addition, plants can add another layer of safety with single-failure-proof trolleys and proprietary closed-loop software options that control the operational path of the crane and protect specific areas.

 

Case study

Palo Verde Generating Station

Polar crane modernization
Three polar crane trolleys plus their cabs and controls were replaced at Arizona Public Service’s Palo Verde Generating Station. Using strand jack technology adapted by Konecranes engineers, KNES was able to safely and rapidly perform work directly over the nuclear reactor. 

Between 2018 and 2021, during a time when most of the country was shut down due to the coronavirus pandemic, Konecranes Nuclear Equipment & Services LLC (KNES) performed comprehensive modernizations of all three polar cranes operating at the Palo Verde Generating Station near Phoenix, AZ.

According to Matt Nemet, manager of global business development for KNES, this was one of the quickest modernizations the company has performed—with a total install duration of just 14 days.

“The facility was originally designed for a 40-year life,” says Nemet. “Modernizations of this level were never anticipated in the original design. A crane modification of this magnitude, during an active outage is unprecedented. Access was extraordinarily difficult with our crews climbing up multiple ladders to reach a very small walkway at the top of the building where much of the work was performed. In addition to adhering to our stringent Prevention of Dropped Items protocol, we had to develop new procedures for operating in these close quarters during COVID.”

The scope of work to be done included replacing the trolley, the cab and all of the controls on each crane with variable frequency drives. In addition, KNES significantly increased interlocks and safety features, added radio controls designed to operate from a remote area on the floor, and installed a troubleshooting and maintenance human-to-machine interface designed to diagnose problems as quickly as possible to minimize future downtime.

KNES brought a special lifting device using strand jacks and hydraulic systems into the containment area for lifting equipment up to the crane. The new trolley had to be raised at a precise 58-degree angle in order to fit through the hatch entering containment, requiring a major engineering effort to design the rigging and safety systems, all of which had to be documented in accordance with the United States Nuclear Regulatory Commission regulations.

“The project finished on schedule,” says KNES Vice President of Engineering Jay Edmundson. “We worked 24/7 to maximize consistency, and we chose to do the turnovers up on the equipment which gave us the ability to reduce the amount of time lost in shift changes. When you compile the amount of time saved on every turnover, it adds up.  Fortunately, KNES has the personnel depth and experience to make this work.”

A range of requirements for a range of cranes

The fuel handling equipment is also critical infrastructure during an outage for defueling and refueling the reactor. Depending on the plant type, it is made up of many components used to pull the spent fuel bundles out of the reactor and replace them. The critical issue is that the fuel is highly radioactive inside the fuel bundle. If something drops on the fuel, the bundle could be breached, contaminating the area and potentially threatening human life. Therefore, fuel handling equipment relies on a very precise set of motors and encoders that track exactly where the grapple goes in order to lift the fuel bundles safely. Tolerances are plus or minus 3 millimeters or less.

Each of the crane systems profiled here has its own set of challenges. Polar and Reactor cranes are difficult to access; refueling machines are easier to access but employ higher levels of technology. In addition, nuclear facilities contain 40 to 50 other types of cranes in supporting roles–including cask-handling cranes, turbine-building cranes and smaller, standard cranes in warehouses and shops.

Descending down a usage hierarchy topped by cranes in containment with the hook dipping into the pool to those performing less-stringent activities, each offers specific opportunities for safety and efficiency upgrades. Depending on where the crane sits in this hierarchy and whether it performs over a boiling water reactor or a pressurized water reactor, regulations may require special materials like stainless steel and custom lubricants for items that go into the pool, unique paint requirements, material restrictions, limits on types of castings and special load tests.

 

Criteria for selecting a contractor

Jacking tower
KNES uses a specially designed jacking tower to lift and manipulate components into place at nuclear power plants. The jacking tower can raise items more than 100 feet in the air with a capacity exceeding 50 tons. The special hydraulic head allows the component to be safely grabbed and rotated or tilted to fit into the tightest spaces. Its hydraulic oil is vegetable-based, so no added fire loading enters the secure space.

When you’re ready to choose a contractor there are important questions to ask in your initial analysis:

  • Has the group done this type of work before?
  • Do they have the ability to work on equipment made by others, or only on their own brand?
  • Do they have a sufficient nuclear quality program that has been audited by the nuclear regulator?
  • Do they have service technicians who routinely work at nuclear power generation facilities, and are specifically trained to comply with nuclear safety and regulatory requirements?
  • What is the depth of their engineering capability?

Konecranes Nuclear Equipment & Service LLC has over half a century of experience in the nuclear industry, both in the United States, and in countries all over the world, including Finland, Lithuania, Slovenia, Spain, Taiwan and multiple projects in Canada. The company meets stringent nuclear requirements and is a member of key regulatory and advisory groups, such as the ASME B30 and ASME NOG-1 committees, which set standards for the design of lifting equipment operating at nuclear facilities.

KNES fields a dedicated nuclear engineering team that currently has 80 members, plus additional project management experts offering specific technical expertise. KNES has unduplicated nuclear experience, with the ability to handle both large and small projects, inside and outside containment areas. The staff includes engineers in every discipline applicable to nuclear material handling, including specialized areas such as seismic analysis, safety analysis and regulatory compliance. This is a nuclear engineering team that has secured more than 30 patents for its industry-leading designs.

To date, KNES has performed more than 150 existing fuel handling installations and modernizations. Konecranes nuclear crane modernizations employ its proprietary SUPERSAFE™ single-failure-proof technology, designed to comply with stringent worldwide nuclear regulatory requirements and prevent load drop during a single failure of the lifting system. SUPERSAFE™ single-failure-proof equipment provides an unprecedented level of safety for the most critical operations such as nuclear fuel handling.

There is another assessment that managers must perform when considering their next outage. What are the consequences of failure? When the cost of downtime runs into the millions of dollars per day, and the cost of human life or contamination are incalculable, what is the value of expertise? Crane modernization can help your operation stay safe and productive as cranes age, design standards change, and new safety regulations emerge. It’s really not a matter of whether to modernize. It is simply a matter of who has the best team for the job. 

 

Jay Edmundson has been a chief engineer for 30 years. He is a certified engineer in both Canada and the United States. He has been part of Konecranes for 17 years, and began his nuclear career as a U.S. Navy submarine officer.

 

Talk to a Konecranes Nuclear Equipment & Service expert about modernizations

 

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