Nuclear Plant Journal, May-June 2008

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Integrated Exposure... Continued from page 39 dramatically reducing exposure despite being a high source term plant. Recent initiatives: • We accelerated change-out of Control Rod Blades (CRBs) in L1R12. Thirty CRBs were replaced in support of the cobalt reduction program. • Three feedwater heaters were replaced due to Flow Accelerated Corrosion issues. This has resulted in greatly reduced reactor water iron levels. • Drywell modifications include permanent scaffold, shielding and CRD Track installation. We also established storage locations in the drywell for scaffold and shielding. • The Exelon fleet has initiated the “CRE-3” project. This endeavor includes remote monitoring and associated infrastructure improvements (Wi-Fi, VLAN rollout, fiber optics, etc.), permanent shielding and laser imaging. IERP Details: The focus areas in the IERP include: Gap Analysis, Goal Setting, Water Chemistry Control, Cobalt Reduction, Communication, Chemical Decontamination, Work Planning, Shielding, Flushing, Work Practices, Modifications, Process Improvements, Steam-Sensitive Area Material Condition Improvements, Remote Monitoring, Assessment, and Training. Supporting Examples: • Behavioral Improvements • Dose Goal setting and ownership: Individual departments developed and presented monthly dose estimates for approval to the Station ALARA Committee. Supervision briefs workers daily to individual dose goals. Emergent work requires further approvals up to and including the Station ALARA Committee. Brainstorming sessions: • All departments participated in a brainstorming session prior to Unit 1’s 10th refueling outage to develop actions to reduce overall exposure. More than 400 unique suggestions were made. The Outage Dose Reduction High Impact Team evaluated them, and approximately 50 actions were taken to reduce the outage exposure by 8 p-rem. Training: • Radworker Dynamic Learning Activity: Included High Radiation Area access requirements, reducing PCEs, working ALARA, etc. • Use of valve mock-ups Cobalt Reduction: • We eliminated (20) Stellite wedges on the new Jet Pump inlet mixers and replaced them with non-cobalt wedges (X-750 alloy) during Unit 2’s 10th refueling outage. • Cobalt mapping: extensive liquid sampling and analysis was performed to help identify primary sources of cobalt. • Elemental cobalt sampling and analysis: LaSalle was the first Exelon facility to perform the sampling, X-ray Fluorescence (XRF) metal analysis and cleaning of residual cobalt from valves and other components. • Three valves containing Stellite were cut out and replaced with non-Stellite valves in 2006 and nine more Heater Drain Check valves (10'' and 14'' were cut out and replaced in 2007. Shielding: • Permanent drywell shadow shielding was installed in the U-1 and U- 2 Drywells around the Reactor Recirculation suction piping and ring headers, Residual Heat Removal and Reactor Water Clean-up piping. These modifications save approximately 25 person-rem each outage. • Ten Emergency Core Cooling System (ECCS) suction penetrations from the U-1and U-2 Suppression Pool had permanent shielding installed. • Dose rates on the piping dropped from 250-2500 mr/hr at contact down to 9-150 mr/hr. Work area dose rates decreased by an average of 80%. • Seven High Radiation Areas were eliminated. Process Improvements: • A Mechanical Maintenance (MM) technician developed a new method to chemically clean the service water seal coolers for our RHR pumps. Dose is decreased by 20 mrem/pump and ECCS system availability is improved. The method we had been using was to add vinegar to the cooler and let stand 4-7 hours to allow the chemical to breakdown the scale buildup inside only to end up spending additional time at the site with a pressure washer to remove scale buildup. The device that the MM came up with is a water pump and hose assembly that connects to the vent and drain lines to allow a recirculation process of the vinegar to the cooler. • The storage racks used to support our old jet pump mixers were electro-polished to reduce radiation build-up and facilitate future decontamination. Remote Monitoring Improvements: • Fiber optic backbone installed • Remote Monitoring Control Room established • Crash carts with video, dose rate and audio 1. Real-time dose rate monitoring in drywell during outages and in RHR corner rooms via wireless remote (WRM) electronic dosimeters 40 http://www.NPJOnline.com Nuclear Plant Journal, May-June 2008
Modifications: Installation of the following in Unit 2’s 11th refueling outage in 2007 and Unit 1’s 12th refueling outage in 2008: • Permanent Control Rod Drive track in the drywell • Permanent drywell scaffolds • Drywell shielding and scaffold storage Steam-Sensitive Area Material Condition Improvements: • Cut out and replaced numerous leakprone Heater Drain check valves • Replaced components susceptible to wear in air-operated valve (AOV) actuators with D2 hardened steel • Installing flex lines on various AOV’s in place of copper tubing • Replacing manual valves and high and low level switches on Reheater drain tanks • Valve packing improvements and training craft personnel on repack/ repair • An innovative shield wall was built to support installation of the Digital Electro-hydraulic Control modification. A 12 ft. beam with four layers of lead shielding was suspended from the Turbine crane to reduce shine from the U-2 Main Turbine. The dose estimate was reduced from 5.32 man–rem to 1.3 man-rem. Transferability: This approach is transferable to any site that is willing to change their approach to employee involvement and engagement. This provides benefits for more than just dose reduction. This approach has also been successful generating ideas for reducing outage duration and improving safety system availability. The keys are to build the plan with the workforce and to communicate how their ideas have benefited the site. This strategy guarantees the pipeline for new ideas will not be stagnant and will help LaSalle achieve its goal of top decile CRE performance. Contact: Ed Wolfe, Exelon, 2601 N. 21 st Road, P.O. Box 220, Marseilles, IL, 61341; telephone: 815-415-2521, fax: 815-415-4018, email: Edward.wolfe@ exeloncorp.com. www. radiation training.com has a special significance to us. And it does to your facility, too. With “N”, “NPT” and “NS” Certificates covering Class 1, 2 and 3 Valves, Pressure Vessels, Pumps, Supports, and Parts, code reconciliation, designing, supplying, replacing, and maintaining certified equipment is just part of our extensive repertoire of services. So besides being the first letter in our name, “N” gives us the “in” on providing superior ASME Section III N-Certificate products and services to the nuclear industry. And that’s always been our incentive. Call us when engineered excellence is indicated. NUCLEAR LOGISTICS INC > the single source www.nuclearlogistics.com 800.448.4124 Circle 114 on Reader Service Form Nuclear Plant Journal, May-June 2008 http://www.NPJOnline.com 41
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Nuclear Plant Journal, May-June 2008

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