catawba nuclear station industry perspective – hdpe applications and economic benefits steve...
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Catawba Nuclear StationIndustry Perspective – HDPE Applications and Economic
Benefits
Steve Lefler - Principal Engineer Duke Energy
Catawba Nuclear Station Industry Perspective on HDPE Applications and Economic
Benefits
• Located 19 miles southwest of Charlotte, NC on shores of Lake Wylie
• Two Units 1160 MW each (net) Westinghouse PWR
• Main condenser cooling provided by forced draft cooling towers
• Once through service water systems use Lake Wylie for cooling
• Commercial operation in 1985 (Unit 1) and 1986 (Unit 2)
• Catawba is jointly owned by:
• North Carolina Electric Membership Corporation
• North Carolina Municipal Power Agency Number One
• Piedmont Municipal Power Agency
• Duke Energy
Catawba Nuclear StationIndustry Perspective on HDPE Applications and Economic
Benefits
• Site Background
• Low Pressure Service Water System secondary cooling and cooling tower makeup. (Designed to ASME B31.1 Code or Civil Building Codes)
• Nuclear Service Water System cooling to nuclear safety related components that now includes 4000 feet of HDPE. (Designed to ASME Section III ND Code)
• Both systems combined total approximately 45,000-50,000 feet of piping
Catawba Nuclear Station Industry Perspective on HDPE Applications and Economic
Benefits
• Site Background
• Low Pressure Service Water System secondary cooling and cooling tower makeup. (Designed to ASME B31.1 Code or Civil Building Codes)
• Nuclear Service Water System cooling to nuclear safety related components. (Designed to ASME Section III ND Code)
• Both systems combined total approximately 45,000-50,000 feet of piping
Catawba Nuclear Station Industry Perspective on HDPE Applications and Economic
Benefits
• Operating Issues with original carbon steel piping
• Fouling and Occlusion
• General Corrosion
• Through wall pin hole leaks
• Selective Weld Zone Attack
Catawba Nuclear Station Industry Perspective on HDPE Applications and Economic
Benefits
Fouling of carbon steel piping
Catawba Nuclear Station Industry Perspective on HDPE Applications and Economic
Benefits
Fouling of carbon steel piping
Catawba Nuclear Station Industry Perspective on HDPE Applications and Economic
BenefitsHDPE piping -generator hydrogen coolers
Catawba Nuclear Station Industry Perspective on HDPE Applications and Economic
Benefits
comparison of carbon steel and HDPE generator hydrogen cooler pipe
Catawba Nuclear Station Industry Perspective on HDPE Applications and Economic
Benefits
• Reliability improved with use of HDPE
• Before replacement with HDPE:– Flow control valves fully open to the containment ventilation chillers
–Chiller condenser pressures near 150 psig trip set point
• After replacement with HDPE and two operating cycles:–Flow control valves 50% open–Chiller condenser pressure around 125 psig
Catawba Nuclear StationIndustry Perspective on HDPE Applications and
Economic Benefits
ASME Class 3 HDPE
•Unit 1 realized a 20-25% flow margin improvement due to HDPE.
•Unit 2 has data indicates that improvement will be on the order of 15%. The Unit 2 improvement is less than Unit 1 improvement because of the smaller amount of buried piping on Unit 2.
Catawba Nuclear Station Industry Perspective on HDPE Applications and Economic
Benefits
Selective weld attack of carbon steel piping
Catawba Nuclear Station Industry Perspective on HDPE Applications and Economic
Benefits
Selective weld attack of carbon steel piping
Catawba Nuclear Station Industry Perspective on HDPE Applications and Economic
Benefits
External corrosion of buried carbon steel piping
Catawba Nuclear Station Industry Perspective on HDPE Applications and Economic
Benefits
Installation of 32 inch HDPE piping
Catawba Nuclear Station Industry Perspective on HDPE Applications and Economic
BenefitsInstallation of 32 inch HDPE piping
Catawba Nuclear Station Industry Perspective on HDPE Applications and Economic
Benefits
HDPE Piping
Catawba Nuclear Station Industry Perspective on HDPE Applications and
Economic Benefits
HDPE piping
Catawba Nuclear Station Industry Perspective on HDPE Applications and Economic
Benefits
• Success with use of HDPE for non safety system service water system led to decision to pursue use of HDPE for safety related nuclear service water system
• EDF Sizewell B Nuclear Station installed HDPE in ASME Section III Class 3 system and now has several miles of HDPE installed in nuclear safety related cooling water piping in the United Kingdom.
Catawba Nuclear Station Industry Perspective on HDPE Applications and Economic
Benefits
•Summary of Catawba Relief Request•Limited to replacement of buried ASME Section III Class 3 service water piping for the four emergency diesel generators for Units 1 and 2
•HDPE design and installation requirements based on draft of Code Case N-755 Rev. 0
•Limited to HDPE Pipe, Mitered Elbows and Flange Adapters
• Limited to Butt fused joints and flanged joints
Catawba Nuclear Station Industry Perspective on HDPE Applications and Economic
Benefits
Timeline – Catawba HDPE Use•1995 – HDPE used in non safety service water system •June 2005 – Meeting with NRC to discuss HDPE for ASME Class 3 •October 2006 – Relief request submitted to the NRC•March 2007 – ASME Code Case N-755 issued•May 2009 – NRC issued Catawba safety evaluation •June 2009 – Began installation of ASME Class 3 HDPE piping•October 2010 – Unit 2 ASME Class 3 HDPE, buried service water piping to the emergency diesel generators completed and in service•June 2011 – Unit 1 ASME Class 3 HDPE, buried service water piping to the emergency diesel generators completed and in service
Catawba Nuclear Station Industry Perspective on HDPE Applications and Economic
•Summary of Catawba HDPE for nuclear safety related cooling water piping• 4,000 feet of 12 inch HDPE pipe, SDR 11 (1.159 in. wall
thickness)• HDPE 4710 Material (ASTM D3350 cell classification
445574C)• Replaced 10 inch sch 40 carbon steel piping abandoned
in place• Transitions from HDPE to steel were made in
underground vaults• Impact tensile testing performed to demonstrate joint
integrity
Catawba Nuclear StationIndustry Perspective on HDPE Applications and Economic
Benefits
•Safety Evaluation for Catawba
•Supplemental Requirements to Code Case N-755 imposed by the NRC safety evaluation issued for the Catawba relief request.
• HDPE flaw depth allowance of 0.041 inches• Reporting of ongoing industry HDPE test program results• Periodic tensile impact testing of field joints• Provision for access to inside of pipe• Remote visual inspection of fused joints from inside pipe
Catawba Nuclear Station Industry Perspective on HDPE Applications and Economic
Benefits
Installation of 12 inch ASME Cl. 3 HDPE piping
Catawba Nuclear Station Industry Perspective on HDPE Applications and Economic
Benefits
Installation of 12 inch ASME Class 3 HDPE piping
Catawba Nuclear StationIndustry Perspective on HDPE Applications and Economic
BenefitsAccess to inside of HDPE piping provided by tee with blind flange
Catawba Nuclear Station Industry Perspective on HDPE Applications and Economic
Benefits
Fusing 12 inch ASME Class 3 HDPE piping
Catawba Nuclear StationIndustry Perspective on HDPE Applications and Economic
Benefits Fusing joint for ASME Class 3 HDPE
Catawba Nuclear Station Industry Perspective on HDPE Applications and Economic
Benefits
Catawba Nuclear Station Industry Perspective on HDPE Applications and Economic
BenefitsInstallation of 12 inch ASME Cl. 3 HDPE piping
Catawba Nuclear StationIndustry Perspective on HDPE Applications and Economic
Benefits
Evaluation for Gouge Depth in HDPE Piping
Catawba Nuclear StationIndustry Perspective on HDPE Applications and Economic
Benefits
Typical scratches in HDPESample
NPS DR Depth %
1 24 9 0.022 in
0.8
2 24 9 0.140 in
6.3
3 8 17 0.029 in
5.5
4 8 11 0.029 in
3.7
5 30 21 0.049 in
2.7
6 30 21 0.032 in
2.3
7 12 11 0.039 in
3.3
8 12 11 0.071 in
6.1
9 10 11 0.047 in
4.9
10 20 11 0.002 in
0.001
Sample 5
Evaluation for Gouge Depth in HDPE Piping
Catawba Nuclear StationIndustry Perspective on HDPE Applications and
Economic Benefits
Catawba NRC Safety Evaluation RequirementsPeriodic Tensile Impact Testing
•Impact tensile testing performed on daily and random samples of fused joints.
•Impact tensile test first fusion joint of each work shift for each fusing machine (daily joint).
•Impact tensile test one random fusion joint chosen during a four work shift period.
•At least 10 percent of field joints from each machine required to be tested during a production shift.
• Fused joints involving fittings were excluded from random testing.
Catawba Nuclear StationIndustry Perspective on HDPE Applications and Economic
BenefitsASTM F 2634, Standard Test Method for Testing PE Butt Fusion Joints
Catawba Nuclear StationIndustry Perspective on HDPE Applications and
Economic Benefits
Catawba NRC Safety Evaluation RequirementsPeriodic Tensile Impact Testing
UNIT
Joints Daily Joints
RandomJoints
JointsTotal
% of Joints Teste
d
1 107 66 16 189 43%
2 63 40 8 111 43%
1&2
170 106 24 300 43%
Catawba Nuclear StationIndustry Perspective on HDPE Applications and
Economic Benefits
Catawba NRC Safety Evaluation RequirementsPeriodic Tensile Impact Testing
•No failures of tensile impact tests provided high level of confidence in installed fused joints
•A minimum of 20% of the joints were tested each work shift compared to the minimum of 10% required by the safety evaluation
•Random testing performed on 13% of the Unit 1 joints
•Random testing performed on 11% of the Unit 2 joints
Catawba Nuclear StationIndustry Perspective on HDPE Applications and
Economic Benefits
Estimated Project CostAugust 2006
Item 6% Moly HDPE
Total Project $ (millions)
32.6 20.9
Material Cost$ (millions)
13.8 2.9
Labor Cost$ (millions)
18.5 17.6
Catawba Nuclear StationIndustry Perspective on HDPE Applications and
Economic Benefits
Relative Material Costs
Catawba Nuclear StationIndustry Perspective on HDPE Applications and
Economic Benefits
Comparison of 6% Moly and HDPE Materials
Item 6 % Moly HDPE Carbon Stl
Pipe $750 $61.70 $33.30
90o Elbow $8070 $600 $558.31
Tee $8507 NA -
Flange $4336 - -
Joints 10 hours 30 minutes 10 hours
Catawba Nuclear StationIndustry Perspective on HDPE Applications and
Economic Benefits
Much of the potential cost savings was not realized.Project costs that were not accurately estimated or considered:
•Cost for testing of HDPE joints •Qualification of fusing process•Excavation •Backfilling•Transition vaults for flanged joints•Costs associated with schedule delays and changes
Catawba Nuclear StationIndustry Perspective on HDPE Applications and
Economic Benefits
Target Areas to Support Future HDPE for nuclear safety related cooling water service
•Regulator approval of ASME Code Case for use of HDPE •Non Destructive Testing for Joints and Acceptance Standard•Resistance to slow crack growth at higher temperatures•Fusion joint process qualification
•Complete development of code requirements for above ground use of HDPE and regulator approval.•Develop approval for use of electrofusion joints•Approval of additional fittings (tees, reducers, branch fittings)
Catawba Nuclear StationIndustry Perspective on HDPE Applications and
Economic Benefits
Summary
HDPE used in service water piping at Catawba has proven to be effective and cost efficient for solving fouling and corrosion problems.
Questions?