Nuclear Power Plant in Japan Shares its Best Practices

Reliability is increased and equipment life is extended through practice and a continuous pursuit of best practices. That is the mind-set of Shikoku Electric Power Company. And, it is the credo of four maintenance professionals who are leading meaningful change at the company's Ikata nuclear power plant.

The team's work is shown in this article through its efforts to transform the Ikata plant's lubrication storage room as well as the site's overall maintenance strategy.

Land of Rising Uptime
Shikoku is the smallest (140 miles long and between 30 and 95 miles wide) and least populous (4.14 million residents) of the four main islands of Japan. It is located south of Honshu and east of the island of Kyushu. The Shikoku region, comprising Shikoku and surrounding islets, covers more than 7,250 square miles and consists of four prefectures (sub-national jurisdictions): Ehime, Kagawa, Kochi and Tokushima.

These prefectures depend on Shikoku Electric. Forty percent of this area's power needs are supplied by the Ikata nuclear station. The site encompasses 9.26 million square feet and generates 2,022 megawatts (MW) of power.

The CBM team at the Ikata nuclear power plant includes (from left) Masanori Sugihara, Yuji Yano, Itsuo Hirose and Takefumi Taguchi.

With such an importance placed on this power plant, uptime and reliability must be the norm; breakdowns and chaos are unacceptable. Plant maintenance ensures that all goes as planned. A four-man condition-based maintenance team inside the group has provided some excellent examples. The group - consisting of diagnostic oil analyst Yutaka Yano, predictive maintenance project leader Itsuo Hirose, chief engineer for vibration analysis Takefumi Taguchi and assistant group leader Masanori Sugihara - monitors the health and well-being of critical equipment (including all rolling-element machines) through oil analysis, vibration analysis and other predictive technologies.

Storage, Filtration & Transfer
This past March, the team completed a project to revamp the plant's lubrication storage room. It maximized space in the 861-square-foot layout by installing a multi-level rack system (from IFH Group) that houses cube-shaped storage containers. These units are tagged and identified with a color code based on content and plant application. See-through gauges allow maintenance personnel to examine oil condition and the amount of oil remaining in the container. Desiccant breathers and a unique dispensing port under the rack were also installed.

At left, dispensing ports on the lubrication storage rack. At right, drum toppers are colored red, gray, yellow based on purpose or application. (Photos by Michinari Yoshikawa.)

Also implemented were filtration units that act as a portable filtration station, ensuring higher levels of oil cleanliness when used in daily operations, including filtering new oil directly from the drum, filling small totes and acting as an offline filter for critical equipment. Particulate and water contamination can corrupt new fluid during processing, mixing or handling. This contamination can be prevented or removed with the installed system. The Ikata plant has now instituted policies that require filtration to target cleanliness levels.

The team addressed lubrication transfer and filling tasks by scrapping conventional oil jugs and standardizing on new LubeRite models that keep contamination out and feature colored identification bands that coincide with the colors on drum units. That way, the threat of using the wrong lubricant for a given application is greatly reduced.

The Push to be Proactive
The Ikata plant's first reactor system went on line September 30, 1977. At the time of its installation, durable service life years for critical plant equipment was estimated at 30 years, meaning such assets are currently well into the mature phase. In order to avoid degradation and/or failure of equipment, the plant turned to condition-based maintenance in recent years. The thought was that, if done right, CBM could help equipment achieve life cycles nearly twice that of the previous prognostications.

Standardization practices have reduced the quantity of lubricant types used and stored at the plant.

Utilizing vibration analysis, oil analysis, thermography and other predictive technologies, CBM can assure system integrity or pick up on symptoms of degradation and unreliability. Early detection can then allow maintenance and operations personnel to address potential issues on a planned and proactive basis, thus minimizing downtime and impact on power generation.

Shikoku's history with CBM is fairly brief. Ikata started down this path in March 2005 when Taguchi expanded the usage and viability of vibration analysis, and team leader Hirose began to explore the full possibilities of oil analysis. Hirose traveled to North America and documented a host of best practices on oil analysis from nuclear power generation facilities in the United States. Upon returning to Japan, he supplied the information to Yano and appointed him the diagnostic oil analyst. This turned into an all-consuming project and passion for Yano. Starting from scratch, he worked to identify all lubrication points for rotary machines, as well as document oil types and inventory throughout the plant.

The interpretation and usage of CBM expanded as Ikata moved forward. In the eyes of the maintenance team, "predictive" was not enough. The drive needed to be more aggressive and advanced. Picking up on the early signs of failure was still an indication of failure. The team wanted to address the factors that could lead to potential early stage issues.

"Find the symptom of machine failure in advance and then take the correct prescribed action," says Hirose. "Proactive maintenance - that's that we were after."

Hirose and Yano attended a Noria Machinery Lubrication Level I seminar in Tokyo in August 2006 and came to the conclusion that proactive maintenance would come with a greater utilization of oil analysis. Shortly after the seminar, the team purchased Fourier Transform Infrared Spectroscopy testing equipment and a particle counter, as well a filter cart. They began to analyze samples taken from lube points on critical equipment.

Additional work targeted oil supply and purchasing practices. Yano's investigation determined that 38 types of lubricants were used in rotary equipment inside the plant. Many of these lubricants performed the same functions and had identical properties, but had different names or were supplied by different companies. Different oils were going into the same machines. So, he revised the lubrication plan, rationalizing and standardizing based on application and needs. The 38 lubricant types were whittled down to 22.

A Never-Ending Pursuit
After a great deal of samples and analyses, Taguchi and Yano came to the conclusion that oil analysis was uncovering the symptoms of machinery degradation faster than even vibration analysis. Proactive maintenance - from lubricant reception and storage to lubricant transfer and filling to lubricant application and performance - was in place and functioning at a high level.

Success does not mean that this project is completed. Policies, procedures and tools are continually revised and improved. Goals become more stringent, which is a must in any industry, but particularly in one such as nuclear energy.

Practice and best practices will continue to raise performance and expectations at Shikoku Electric's Ikata plant. The CBM team will be at the forefront of those efforts.