Over the last several years, leading plant operators have demonstrated that availability factors can be improved, operating costs reduced, and safety and reliability enhanced on a long-term basis. Outage optimization is a new term being used to describe these long-term initiatives. A variety of measures aimed at shortening scheduled plant outages have been developed and successfully implemented by these leaders working with their service providers who introduced new technologies and process improvements

New Framatome ANP IVVI bridge installed with refueling bridge at Browns Ferry allows simultaneous inspection and refueling work.

All nuclear plant operators now have ambitious outage optimization plans, and the median and average outage durations are decreasing on a worldwide basis. The high economical impact of outage time reduction is impressively illustrated by the fact that in the last ten years in the US, an additional power output equivalent to ten 1000MWe Nuclear Power Plants (NPP) has been achieved through outage duration reductions – without investing in new plants and without additional plant personnel. Future objectives are even more aggressive and must include plant upgrades and component replacements being performed for life extension of plant operation.

Outage optimization covers a broad range of activities from modifications of plant systems to faster cool down rates to human behavior improvements. It has been proven to reduce costs and radiation doses, avoid unplanned outages and thus support plant availability and help to ensure the utility’s competitive position in the marketplace.

The Concept

Framatome ANP, aware of the strategic importance of its customers’ goals of reducing outage durations, has created an Outage Optimization Project Team that spans all regions and business groups of the company. The concept behind the project is that:

• plant operators drive the outage duration reduction goals
• customers benefit from Framatome ANP’s unique ability to gather and share “best practices” experience on a worldwide basis
• although there is not a single, stand-alone outage optimization product or program that fits every customer and plant, a process can be developed to ensure that every aspect of an outage is analyzed and evaluated. In this way, all opportunities for reducing outages are identified to allow decisions based on solid data
• quality, safety and costs have to be driven simultaneously

Because outage optimization is so important to Framatome ANP’s customers, team members developed an Outage Optimization Handbook that identifies and defines all the activities performed during a typical outage. To identify potential sources of gains, the team performs extensive Window and GAP analysis for all types of PWR and BWR designs. Further to these analyses, looking globally at an outage, its preparation and its experience feedback, the team also performs micro gap analysis focused on specific outage phases where Framatome ANP teams are regularly involved. A series of processes, covering anything that can impact an outage, has been developed to ensure that all sources of gains have been analyzed. In addition, the team examines those maintenance activities that can be performed during normal operations.

Four-Part Analysis System

The window and GAP analyses help the team identify the main constraints and source of delays that impact an outage. To ensure that everything that can affect an outage has been investigated, the team developed a four-part analysis system to identify and implement improvements that move an organization to higher performance:

A. Soft Skills – planning, scheduling, communications, ownership, scope control, task management, long-term outage strategy – all those items that are human behavior driven, nearly free of cost, but are present in every successful outage organization in the world.

B. Specific Task Improvements – refueling, steam generator, pump and motor, valve maintenance - those typical areas that have always been the domain of the service vendor to bring advanced tooling, robotics, and skilled personnel to perform specific tasks usually confined to outages.

C. System Engineering Improvements – technical specifications, faster cool down rates, water management plans, chemistry, license changes, and reliability-centered maintenance practices, all applied to shorten outage windows or eliminate outage tasks.

D. Major Modifications to plant systems, structures or components to shorten outage durations. Integrated head packages for US PWRs, permanent cavity seal plates, upgraded fuel handling bridge control systems, and single pass stud tensioning carousels are examples of available improvements.

Improvements in outage duration are obtained through a benchmark and gap analysis process where the plant and the outage team work together to assess the best performances and practices already in place, compare current plans to those best practices, establish the individual site’s risk and financial restrictions, and then implement selected improvements that satisfy the plant’s needs without exceeding their financial limitations. Thus, the final solution varies from plant to plant. Every outage is an individual event.

Outage Optimization

Germany has been a worldwide leader in this area. They initiated an outage optimization process in the beginning of the 90s and achieved outages as short as seven days. To reduce outages from more than 30 days down to seven and increase plant availability, plant operators developed long-term outage strategies, focused on outage planning and management, and established a production-oriented maintenance strategy. Framatome ANP cooperated on the overall planning, especially on critical path activities, optimized personel resources, and developed innovative technologies and tools.

Another example of this type of work already underway is the Sizewell B plant in England. Framtome ANP is part of a consortium that has already helped Sizewell reduce its last performed outage by 16 days. To accomplish this, an Outage Control Center was created along with a High Impact team to optimize outage preparation and performance.

Electricité de France (EDF) has launched an ambitious outage optimization program while maintaining its high safety standards. Framatome ANP is developing service package concepts (B) for some plants as well as working on several engineering issues (C) for tasks on critical path (or near critical) such as specific periodic test or operations constraints at other plants.

In addition, Framatome ANP provides outage optimization consulting and plant evaluation services, plant tooling upgrades including intelligent diagnostic systems, system engineering and licensing services to optimize outage performance, and optimization modifications to plant structure, systems or components.

In the US, as part of several outages, permanent canal seal plates and integrated head assemblies are being installed to reduce disassembly and reassembly times. These are examples of major modifications that can have a positive impact, over the long-term, on outage duration.

Steve Huntington, US Vice President, Outage and NDE Services commented, “By forming a dedicated Outage Optimization Project Team that unites the outage services, engineering and project management functions across the entire company, Framatome ANP offers its customers more than just outage services. By working together with the customer, the company examines every aspect of plant operation from every perspective to minimize unplanned outages through long-term plans for scheduled maintenance, repair and component replacement, if needed. This approach, combined with targeted efforts to reduce outage durations, results in the highest and safest performance possible for Framatome ANP’s customers plants.”