STAR performance at Brown’s Ferry

In 2000, Brown’s Ferry claimed a world record for a BWR by refuelling unit 3 in 18 days, 2 hours and 29 minutes.

Although it started 12 hours behind schedule, the refuelling activity finished 22 hours ahead of the schedule on critical path. Extensive up-front planning, experienced TVA and contractor work teams, and low equipment breakage were contributing factors to the schedule improvement.

More than 340,000 work hours were invested in the outage between 15 April, when unit 3 shut down, and 3 May when it was reconnected to the grid. In that time, Browns Ferry employees completed 850 preventative maintenance items, 863 work orders, 47 modifications, and more than 1500 post-maintenance tests.

“Brown’s Ferry employees strive to be the best they can,” said John Herron, Brown’s Ferry site vice president. “Through the use of STAR 7 (Strategic Teamwork for Action and Results), the site organisations are communicating more effectively and working together better than ever before to contribute to TVA (Tennessee Valley Authority).”

“One of the most significant contributors to the successful unit 3, cycle 9 (U3C9) outage execution was adhering to our plan,” said Elvis Hollins, senior outage manager at Browns Ferry. “Since we developed a boiler plate logic several outages ago, we have proven several times that our plan is reliable, safe, efficient and able to be performed.”

Using the same logic at each outage simplifies the inclusion of new or specific issues for each outage, reduces the complexity of the outage, and provides the platform for easily assessing emergent problems that occur during the outage.

Pre-outage work

Preparations for the U3C9 outage began 12 months prior to the start of the outage. Lessons learned from the unit 2 cycle 10 refuelling outage were reviewed and assigned to 10 different high impact teams (HITs) for corrective action development and implementation.

Each HIT, a diverse group of employees, were assigned to assemble ideas for improvements and then co-ordinate pre-outage activities. The 10 teams covered:

•MOVATS.

•Turbine generator.

•Refuel floor/ADHR.

•Plant component inspections, evaluations and containment coatings.

•Dose estimation.

•HPCI/RCIC scope review.

•24-month cycle compliance review.

•Primary containment co-ordination.

•Leak inspections and repairs.

•Job fair.

Teams met at different intervals monthly, bimonthly and weekly toward the pre-outage milestone completion window. Action items were assigned and tracked for completion, and the HIT provided focused attention in specific outage areas.

An additional benefit of HIT was the increased spirit of teamwork and co-operation between the various departments and organisations. In general, successful HITs continue from one outage to the next, building on the lessons learned and experience gained by the members. For this reason, a high return rate of HIT members is essential.

The original U3C9 outage schedule called for a duration of 17 days and 12 hours, with the following goals in mind:

•Safe and efficient U3C9 refuelling.

•No lost time accidents.

•Maintain personnel radiation dose as low as reasonably achievable, and less than or equal to 128manrem.

•Zero licensee event reports due to personnel errors.

•Zero NRC violations.

•Zero recordable injuries.

•Perform outage on budget.

One key initiative of the successful outage was pre-outage planning. Major modifications, improvements, and components needing maintenance were discussed by all involved departments, and then planned, approved and scheduled. Outage materials were ordered in advance. Equipment, tools, and other resources were co-ordinated, procured, and expedited. Contractors were hired as needed, and trained to gain access into the plant.

Typically, the preparation, planning and co-ordination for the next scheduled outage begins immediately after the current outage is over, and all departments become involved in the planning.

Operations

Another significant contributor to outage performance was Browns Ferry’s method for maintaining informed operations individuals for the duration of the outage.

For several years, Browns Ferry used senior operations personnel during the outage preparation phase to provide their perspective and input on the plan. Prior to 1997, these personnel were released at the start of the outage to return to normal shift duties. Beginning in 1997, these individuals were assigned to oversee outage operations from the control room. This change produced a significant improvement in operations’ execution of the outage.

The outage senior operations personnel briefed the operations department prior to the outage on all aspects of the outage. They prepared summaries of the significant evolutions that highlighted previous or anticipated problems, previous lessons learned, predecessor and/or successor evolutions, technical specifications requirements and risk minimisation.

Providing the on-shift operations crew with this knowledge eliminated work stoppage or significant slowdowns and plan deviations due to questions or concerns arising during the outage on equipment issues or technical specification compliance issues.

Refuelling operation

To achieve the aggressive refuelling goal, innovation was needed from the site.

Bill Hayes and Mike Keck participated in a TVA nuclear team that won a TIP award for developing an innovative fuel shuffle process. The “quadrant-based in-core shuffle” was praised at the Nuclear Energy Assembly in Chicago, USA in May 2000. The TIP Award recognises creative new practises that improve safety and efficiency in nuclear plants. These awards honour ideas that can be shared within the industry.

The quadrant based in-core shuffle can be used by other utilities that operate BWRs. The only cost of the technique is additional planning and analysis by the shuffle design engineer.

Schedule performance

The 18 day, 2 hours, and 29 minutes breaker-to-breaker outage was Browns Ferry’s second world record for a BWR. The outrage team attributed its success to the support provided by all the Brown’s Ferry organisations, as well as incorporating many of the more than 800 lessons that were learnt from the site’s previous outages.

“The TVA value of ‘teamwork’ was a key characteristic demonstrated by all Browns Ferry employees and organisations which helped Browns Ferry complete the outage in such a short time,” said R Jones, Browns Ferry plant manager during the U3C9 outage. “We knew we would have to solidify teamwork to deal with upcoming challenges in order to cut precious time off the critical path.”

As part of its improvement in teamwork TVA has adopted a cultural change programme entitled STAR 7 (Strategic Teamwork for Action and Results). As part of this programme seven TVA values have been identified as integrity; respect for the individual; accountability; teamwork; innovation and continuous improvement; honest communication; and flexibility.

STAR 7 has made a difference at Browns Ferry.

Major plant modifications

Major plant modifications that challenged the Browns Ferry team were the turbine low-pressure rotor ‘C’ inspection and reassembly, hydrogen water chemistry, and noble metals injection.

In addition, the recirculation pump motor generator inspections and testing required a total rebuild of the electronic controls for the recirculation motor generator set along with disassembly, cleaning, inspection, and testing of the stator and rotor. The reactor feed pump control oil system was upgraded with a filter delta pressure indicator due to problems encountered during the pre-outage. Finally, the unit was converted to a 24-month fuel cycle from the previous 18-month fuel cycle.

Radiological control

The total radiation dose for the outage was 114 manrem, compared to a goal of 128 manrem.

Historically, Browns Ferry’s radiological record improvement illustrates employee commitment to the ALARA programme from a high of approximately 325 manrem during the U2C9 outage to 114 manrem during the U3C9 outage. ALARA initiatives included using temporary lead shielding, which saved 12.7 manrem, and an innovative contamination control technique which saved 0.5 manrem. The outage team focused daily on dose accrual to ensure the goal was achieved.

Hydrogen water chemistry and noble metals injection were two outage activities which added to the complexity of the U3C9 outage. “Though these activities added time to the outage duration, it was decided that noble metals would reduce radiation doses for workers in the future,” said Ashok Bhatnagar, Browns Ferry plant manager. “Additionally, hydrogen water chemistry would promote the reduction of inter-granular stress corrosion cracking of components associated with the reactor pressure vessel.”

Budget

The U3C9 outage budget did not exceed that allocated for the previous outages. No additional funds were needed to shorten the outage. Breakage during the outage accounted for approximately 4.3% of the total outage expenditures, but good planning resulted in the outage coming in on budget.

“We have significantly decreased our turbine and refuelling activities by two or more days in the last three years,” said Hollins. “These accomplishments are even more significant since they were done without increasing outage costs. Our future accomplishments are only limited by our vision.”

“Our success at Browns Ferry in outages and all areas of operations,” concluded Herron, “is due to our employees and teams who live the TVA STAR 7 values. They are committed to setting the standard for supplying low-cost, reliable power and improving the quality of life in the Tennessee Valley.”