Millstone Power Station, covering 500 acres, shares its name and site with a long-abandoned quarry, which originally produced round granite stones used to grind grain in the 1700s. It rapidly grew to become one of the largest quarries in the country, and granite from Millstone was used in buildings and monuments throughout the world – the base of the Statue of Liberty, Grand Central Station, the United Nations Building, and more.

Today, uniqueness confronts the Millstone visitor at its main gate. A courteous and well-armed guard confirms a visitors authorization and searches the car. Gaining access to the plant itself involves a personal security check considerably more inclusive than TSA airport security. Once access is gained, the visitor is required to have his assigned yellow pass visible and to stay with a designated escort at all times.

Safety Paramount

During the plant tour, the word safety is heard constantly, over and over, in discussions with plant employees. In fact, the entire nuclear power industry shares that common thread – the overarching goal of producing safe, reliable electricity, said Richard Rogozinski, site engineering supervisor. He pointed out that a large coal- or gas-fired electric generating plant would normally be staffed by 60 to 100 employees, while Millstone has almost 1,300. The difference, he said, relates to the extensive safety measures that are layered like an onion, from the design of the facilities all the way to the day-to-day operations.

Like each of the other 104 commercial operating nuclear reactors in the United States, Millstone has thousands of back-up components and redundant systems that are designed for the sole purpose of bringing the plant to a shutdown in an emergency. These systems are normally never used, except during routine tests which are conducted to ensure each components readiness. Millstones operators devote one full week out of every five exclusively to training, Rogozinski said. The training includes preparing for and responding to every credible accident scenario in a simulated control room. Millstone staff and community leaders routinely participate in emergency preparedness exercises of simulated accidents, as well. The power stations rigorous approach to preventing human error includes detailed procedures, many of which require dual verification of various facts, he added.

The center of this focus on safety, of course, is the two nuclear reactors within their massive, reinforced concrete containment domes, said Project Manager Tom LaFauci. Millstone Unit 2 began operating in 1975 and its operating license runs to 2035. Unit 3 began operating in 1986, and is licensed to 2045. They cost a combined $4.3 billion to build. (Unit 1 was decommissioned 11 years ago.)

Cooling water for the reactors comes from the adjacent Long Island Sound, and continuous environmental monitoring of the adjacent waters provides evidence to the State Department of Environmental Protection that all regulatory requirements are being met. Dominion, Millstones owner, is committed to healthy environmental stewardship, LaFauci emphasized.

No special lubes

Aside from using nuclear fuel as the source of heat, the basics of a nuclear power plant are the same as those of a fossil fuel-fired plant. Water is heated to steam; the steam is directed to the blades of a turbine, causing the turbine to spin; and that, in turn, drives an electric generator.

Norma Bihl, Millstones lubrication specialist and LubesnGreases assigned escort, pointed out, Like any other industrial facility with large rotating equipment, a nuclear plant has most of the same equipment and the same need to reduce wear and friction. We use the same standard, commercially available oils and greases. Many years ago, she explained, one company produced a line of lubricants specifically for nuclear use but later discontinued them. Our market is just too small. After considerable testing, the nuclear industry concluded that, as counterintuitive as it might seem, lubricants are quite tolerant of the radiation effects in nuclear applications. There are no special lubes for nuclear plants.

Of course, the plants overall equipment reliability program requires proper lubrication of the components. Bihl has learned to call these the Five Rights of Lubrication.

It might sound corny, she explained, but each Right contributes to a successful lubrication program at a nuclear plant or anywhere – the right lubricant type, the right quality, the right amount, the right place, at the right time. And a good lubrication program is essential to keep our pumps and motors humming. Additionally, our operators do plant walk-downs every shift and keep an eye out for oil leaks. We schedule routine work to inspect components, grease bearings, sample or change the oil on a regular interval, and our comprehensive condition monitoring program includes oil analysis and other predictive technologies, which we use to evaluate component health. We use our corrective action program to identify any degrading conditions, which may lead to additional troubleshooting or scheduling more extensive corrective maintenance, such as overhauls.

Right Lube Type and Quality

In contrast to non-nuclear facilities, even though we use off-the-shelf lubricants, we step up the scrutiny a notch, Bihl continued. To verify the product quality, our lubes are quarantined upon receipt and evaluated for various characteristics. Most of our lubricants come from blending plants that weve already inspected and approved for quality control. Other lubricants have to be sent off-site for testing at a pre-approved lab prior to use. Our meticulous documentation process allows us to identify the lubricant, by batch number, in every component, and when that component was re-greased or when the oil was changed. That material traceability, backward and forward, has come in handy a few times, such as when we got to the bottom of an oil drum and noticed a few flakes of rust: We were able to double-check how the components were doing that included the oil from that specific drum.

Rogozinski explained that anything that supports reactor shutdown, maintaining the reactor shutdown and preventing radiation exposure is important to safety. Lubricants, too, are an essential factor in ensuring these components operate safely and as designed. Millstone works only with approved vendors, he added. To purchase a product outside of our established vendor list or by sole source requires a great deal of initial and ongoing documentation.

Right Amount, Right Place

Millstone documents each lubricant application, by product name, in formal procedures. We include the lubricant for each component, reservoir capacity (right amount), specific reservoir (right place) or grease fittings, and other pertinent details relating to the physical configuration, such as bearing style or special tools required, Bihl related. So if a vendor reformulates or stops making a lubricant – as ExxonMobil did in 2008 – it can lead to an avalanche of documentation rewrites for Millstone.

Since Millstones early days, we used Mobils DTE 790 Series, specifically DTE 797, a viscosity grade 32 turbine oil, Bihl recalled. It was not only a popular product for other industrial steam turbine users, but Millstone as well as many other nuclear plants also used it extensively throughout the plants in vertical motors and other components.

However, ExxonMobil consolidated its turbine oil product line, discontinuing the DTE 790 series among others, and replacing it with a new DTE 700 series. It is formulated to meet global industry standards for steam and gas turbines, and Bihl pointed out that ExxonMobil performed extensive performance testing prior to releasing its new product. Any other industrial facility would switch products and move on, she said. However, due to the widespread use of DTE 797 in components that are important to safety, Millstone and the countrys other nuclear users of the fluid required independent assessment of the new product.

Fortunately, instead of each of us performing our own testing, Bihl said, the nuclear industry collaborated and enlisted the Electric Power Research Institute (EPRI) to independently evaluate the new oil. We needed to ensure equivalency and compatibility with our old DTE 797 product. This teamwork, and sharing the EPRI test results, saved each nuclear plant a lot of money.

After the independent results were complete and the EPRI formal report was published, a blizzard of follow-up documentation was still needed, including a Millstone engineering evaluation to provide the basis for 75 procedure changes. These procedure changes were required to capture an otherwise straightforward and perfectly acceptable formulation change of one oil type.

The Right Time

Our turbines and many other components operate on a 24/7 basis and equipment reliability is essential. We depend on the lubricants to provide long service life themselves to support these components reliability, Bihl noted. Some of our motors have been in service for several years without an oil change. We glean information about a components health from a robust condition monitoring program, which includes oil analysis, vibration and other predictive technologies to provide early detection of failure.

The key to ensuring long service life of a lubricant is to keep it clean, cool and dry, she added. We purify each of our main turbine oil systems continuously, using a multistage filtration system which includes a prefilter and 2.8-micron polishing filters, vacuum dehydration and coalescing filters. This keeps the water content down and the cleanliness up. We regularly monitor the oil condition and watch for evidence of additive depletion, as well as other changes to assess continued serviceability. After routinely scheduled maintenance we perform extensive turbine oil flushes, additional purification, and verify oil cleanliness.

The product data sheet claims this turbine oil is designed for maximum oil charge life, she continued. That was no sales pitch. Sure enough, weve changed our turbine oil only once in our 34-year history, without ever re-additizing.

Admittedly, a steam turbine doesnt stress its oil nearly as severely as a gas turbine does. Yet Millstones watchful eye concluded that it was the right time to change out the turbine oil, based on its condition (no longer the right quality). So what prompted that turbine oil change?

After extensive testing we saw indications that the additive package was being depleted, by trending the test results for oxidation stability and foam tendency, Bihl replied. Our guidance is extremely conservative, and I am confident that our decision to change out the oil was equally conservative. Its an expensive proposition to change out the entire 10,000-gallon [turbine] oil charge, but conservative guidance and decision-making are just some of the tools that fold into our commitment to safe, reliable production of power.

LubesnGreases paid its visit to Millstone near the 30th anniversary of the incident at Three Mile Island, which colored the publics view of nuclear power in the United States for decades. Renewed interest is being seen now, with a Gallup poll in March saying public support is at an all-time high: 59 percent favor its use, including 27 percent who favor it strongly. President Obama has said that nuclear power is part of his overall plan to expand the use of alternative energy in the United States, and if public support for it continues to grow, it would seem likely that more Americans would come to rely on nuclear energy, the polling company observed. The Nuclear Regulatory Commission has applications on file to build and operate more than 30 new reactors around the country.

By constantly raising the bar for the entire nuclear industry over the last few decades, nuclear power has become increasingly safe and reliable, Millstones staff reiterated. The nuclear industry is a rare group of like-minded comrades. We openly share our own operating experience with our colleagues and competitors, to help each other avoid pitfalls that each of us discovers, and to help each other continually improve, Bihl said.

She summed up, Our commitment is to safe, reliable production of power. That means the safety and health of the general public is foremost in our minds everyday.