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Nuclear Power-Operated Valve Qualification

Nuclear Power-Operated Valve Qualification. & Life Extension. Neal Estep nestep@kalsi.com Kalsi Engineering, Inc. 745 Park Two Drive Sugar Land, TX  77478. Outline. Overview of requirements Nuclear design and construction requirements Nuclear qualification requirements

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Nuclear Power-Operated Valve Qualification

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  1. Nuclear Power-Operated Valve Qualification & Life Extension Neal Estep nestep@kalsi.com Kalsi Engineering, Inc. 745 Park Two Drive Sugar Land, TX  77478

  2. Outline • Overview of requirements • Nuclear design and construction requirements • Nuclear qualification requirements • Nuclear market penetration • Nuclear life extension considerations

  3. KEI Background Kalsi Engineering, Inc. • Having worked with valves and actuators in a variety of industries for well over 35 years KEI can bring some unique perspective on this subject. • Served clients for over 35 years (founded 1978) • Engineering services: Design, analysis, testing, R&D • Industry wide recognized specialist in valves, seals, & mechanical equipment • Nuclear power industry • Oilfield/petrochemical industries • Advanced models, software, hardware, test facilities & patented technologies

  4. Overview of Requirements Valve Product Line NQA-1 Program ASME N,NPT-Stamp Certification Authorized Nuclear Inspector Testing & Model Validation QME-1 Functional Qualification Analysis Qualified Product New Entrant Barriers Market Penetration Product Differentiation Sales & Support Infrastructure Sales $$

  5. Challenges for New Entrants • Expense of implementing a nuclear program • Lack of experience with Nuclear Regulatory Commission operating environment and related history – a fundamental shift in thinking and new learning is required • Lack of Nuclear Industry operating environment experience and knowledge history • Lack of in-plant and industry test data for product line • In-plant diagnostic test equipment and methods are mature for existing product lines

  6. Nuclear Design & Construction Requirements • Client procurement specifications identify the design &construction code, qualification & testing, and other requirements (e.g. weak link analysis). • ASME Boiler & Pressure Vessel Code Section III is required for ASME Class 1, 2, and 3 nuclear safety-related applications. • ANSI B31.1/B16.34 is usually specified for balance-of-plant, non-nuclear safety-related applications.

  7. Nuclear Design & Construction Requirements: Nuclear Class 1 Components within the reactor coolant system pressure boundary.

  8. Nuclear Design & Construction Requirements: Nuclear Class 2 Components important for nuclear safety that typically interface with the reactor coolant system pressure boundary.

  9. Nuclear Design & Construction Requirements: Nuclear Class 3 Components in cooling water and auxiliary feedwater systems that are important to nuclear safety.

  10. Nuclear Design & Construction Requirements Relationship of Nuclear Class to Design Requirements:

  11. Nuclear Design & Construction Requirements ASME Code Service Level Design Requirements: • Primary Stress Limits: Intended to prevent plastic deformation and to provide a nominal factor of safety on the ductile Burst pressure. • Primary + Secondary stress limits: Intended to prevent excessive plastic deformation and to validate the application of elastic analysis when performing the fatigue evaluation. • Peak stress limit: Intended to prevent fatigue failure as a result of cyclic loading (crack initiation)

  12. Nuclear Design & Construction Requirements ASME Code Service Level Design Requirements: • A: Normal Operation: Includes stresses due to normal installation, start-up, shut-down, power reduction, etc. • Considers primary stresses, secondary stresses, and fatigue • B: Upset Conditions (Moderate Frequency): Permits no damage that requires repair. Includes turbine trips, reactor trips, safety-relief valve actuation, operating base earthquakes, etc. • Same as Level A but allows higher limits for primary stresses

  13. Nuclear Design & Construction Requirements ASME Code Service Level Design Requirements: • Can go into a significant level of strain with C and D service limits • C: Emergency Conditions (Infrequent) • Permits large deformations in areas of structural discontinuity. Component is required to be removed from service for inspection and repair. Includes over-pressure events, pressure transients, safe shutdown earthquakes, etc. • Allows up to yield strength (Sy) for primary general membrane stresses • Allows elastic limits for pressure loading with ferritic material up to 90% of Sy • Secondary and peak stress evaluation is not required • D: Faulted Conditions • Permits gross general deformations with damage that requires repair. Includes safe-shutdown earthquakes, pipe rupture / loss of coolant accidents, and other low probability design-basis events. • Evaluated per rules in Appendix F of Section III.

  14. Nuclear Design & Construction Requirements • Manufacturer’s must hold an N-Stamp Certification for Class 1, 2, and 3 valves: • N Certificate: Code Compliance for materials, design, fabrication, installation, examination, testing, inspection, certification, and stamping. • NPT Certificate: Required for fabricating parts, piping subassemblies, or appurtenances.

  15. Nuclear Design & Construction Requirements • Manufacturers must have a QA Program that satisfies NCA-4000 requirements: • ASME NQA-1 • Design Control • Procurement Document Control • Control of Purchased Items and Services • Identification and Control of Items • Control of Processes • Inspection • Test Control • Control of M&TE • Etc.

  16. Nuclear Design & Construction Requirements: Nuclear Inspector • Manufacturer’s must have a relationship with an Authorized Inspection Agency to utilize services of an Authorized Nuclear Inspector (ANI) who will: • Verify scope of work to be performed • Monitor QA program and subcontracted activities • Review qualification records • Verify materials • Witness fabrication, examinations, and tests. • Review and sign reports http://blog.heritage.org/2010/07/26/ahmadinejad-warns-against-further-sanctions-pushes-ahead-on-many-fronts/

  17. Nuclear Design & Construction Requirements • ASME B&PV Code - Sections • Section I: Rules for Construction of Power Boilers • Section II: Materials • Section III: Rules for Construction of Nuclear Power Plant Components • Section IV: Power Boilers • Section V: Nondestructive Examination • Section VI: Recommended Rules for the Care and Operation of Heating Boilers • Section VII: Recommended Guidelines for the Care of Power Boilers

  18. Nuclear Design & Construction Requirements • ASME B&PV Code • Section VIII: Rules for Construction of Pressure Vessels • Section IX: Welding and Brazing Qualifications • Section X: Fiber-Reinforced Plastic Pressure Vessels • Section XI: Rules for In-service Inspection of Nuclear Power Plant Components • Section XII: Rules for the Construction & Continued Service of Transport Tanks

  19. Nuclear Design & Construction Requirements • Nuclear customers require that the design consider the maximum and minimum ranges: • Minimum and maximum friction coefficients • Minimum and maximum voltage conditions • Minimum and maximum supply pressure conditions • Etc. • Required for stress analysis, seismic, weak-link, and sizing the actuator

  20. Nuclear Design & Construction Requirements • The resulting design often resembles an elephant (actuator) riding a bicycle (valve) Actuator Valve http://successfulworkplace.com/2012/10/28/big-data-must-not-be-an-elephant-riding-a-bicycle/

  21. Nuclear Functional Qualification Nuclear Plants must demonstrate on an on-going basis that their POVs will function under worst case conditions that (hopefully) may never be seen during normal plant operations. Evolution of Functional Qualification Standards: Old New ANSI N278.1-1975 Valve Specification Guidance ASME QME-1 Very comprehensive, but costly to fully implement ANSI B16.41-1983 Functional Qualification

  22. ASME QME-1 • QME-1 Requirements Overview • Identify product line to be qualified • Develop qualification plan, including analytical model development and qualification extension approach • Develop test procedures • Perform testing • Validate analytical model and qualification extension approach from test data • Prepare functional qualification report • Prepare application reports (as needed) for customers

  23. ASME QME-1 (continued) • Establish Qualified Valve Assembly • Develop methodology to extrapolate qualification of valve assembly • Assure Production Valve Assembly performs as predicted by Qualified Valve Assembly • Applies for: • Valve • Actuator • Valve and Actuator Interface

  24. ASME QME-1 (continued) Documentation Requirements • Qualification Plan • Translates the Qualification Specification into a step-by-step qualification program. • Functional Qualification Report • Documents compliance of the qualified valve assembly and its production valve assemblies • Application Report • Documents suitability of any qualified valve assembly and its production valve assemblies for a specific nuclear plant application

  25. Qualification Issues • Assessment of stresses, strains, loads, or displacements against allowable capacity limits. • Analysis should be sufficiently rigorous to allow for scaling from small to large sizes. • Deflections should not create interference, impede function, cause galling, or a lack of functionality.

  26. Qualification Issues • Aging: Must consider aging effects on both design (corrosion, erosion, etc.) and function (degraded seats, friction factors, etc.). • Differences in normal operation and accident conditions: • Pipe break requirements can drastically increase flow-rate requirements for the same DP, or greatly increase both DP and flow-rate requirements. • Accident conditions may require consideration of harsh environmental conditions: temperature, humidity, radiation, corrosive spray, etc.

  27. Qualification Issues: Flow Rate Effect on Globe Valve Performance • The required thrust to operate a globe valve can increase significantly with higher flow rates due to increase in side load on the plug and the corresponding increase in friction due to side load • Side load friction for a globe valve depends upon • The key valve design/dimensional parameters • The flow rate, which depends upon valve resistance relative to the system resistance • The friction coefficient of the material pair • Damage to the valve internals can occur if localized loads/stresses exceed threshold of galling

  28. Qualification Issues: Flow Rate Effect on Globe Valve Performance Flow loop tests were performed to determine the effect of flow rate on globe valve performance

  29. Qualification Issues: Flow Rate Effect on Globe Valve Performance Blowdown • Increase in flow rate dramatically increased the valve operating thrust • Blowdown conditions resulted in galling damage to the internals • Detailed CFD/FEA model validated, provided bounding predictions Vmax = 50ft/s

  30. Qualification Issues: Flow Rate Effect on Butterfly Valve Performance – Incompressible flow High Flow ( 2xNormal Flow) Hydrodynamic Torque Normal Flow ( 3 DPs) Angle Hydrodynamic Torque For Butterfly/ Other Quarter Turn Valves Increases Modestly with DP, but Increases Significantly with Flow Rate Increase

  31. Qualification Issues: Flow Rate Effect on Butterfly Valve Performance – Compressible flow . . Torque Coefficients ( Compressible Flow) Depend on Pressure Drop Ratio • Butterfly Aerodynamic Torque depends strongly on Flow Rate (dictated by DP/P1 Ratio); • Torque can even switch from self-closing to self-opening based on flow rates for certain designs

  32. Qualification Issues: Flow Rate Effect on Gate Valve Performance • For high flow conditions, fluid forces can cause disc to tip (instead of remaining flat against guides or seat under low flow conditions) and result in damage to gate valve internals • Manufacturer’s experience based on years of satisfactory performance under normal plant flow rates does not serve as an acceptable technical basis to justify performance under high flow/accident conditions in nuclear power plants

  33. Qualification Issues: Flow Rate Effect on Gate Valve Performance Disc/Seat Face and Guide Damage After A Blowdown Closure Test by NRC/INEL

  34. Qualification Issues: Flow Rate Effect on Gate Valve Performance Fluid Flow Around Disk Force & Moment Equilibrium Equations Internal Reaction Forces Detailed First Principles Gate Valve Models to Predict Thrust Requirements Permit Qualification of the Entire Product line Based upon prototype testing and Model Validation

  35. Barriers to Entry Into Nuclear • High Switching Costs for Nuclear Utilities • Procedures • Spare Parts • Training & Qualification • Standardization Efforts • Mature programs for existing equipment • Business relationships – comfort, history, familiarity • Diagnostic test equipment and practices

  36. Items Required by Nuclear Decision Makers • Product conforms to specifications: ASME Code, NQA-1, Size, ANSI Class, etc. • Environmental effects on capability (e.g. temperature) • System effects on capability (e.g. voltage) • System effects on requirements (e.g. P, DP, Q, fluid type, fluid temperature, cleanliness, etc.) • Degradation (Age- and Service-related) • How to calculate required torque under different operating conditions • How to perform field diagnostic testing

  37. Fundamental Need • Required torque or thrust calculation methodology must be test-based to meet regulatory requirements • 10CFR50.55a, GL 89-10, ASME OM OMN-1/App III • Methodology must account for various system and environmental conditions • Methodology must account for age- and service-related degradation • GL 96-05

  38. How to Address • ASME Design & Construction Code (Section III) • ASME Functional Qualification (QME-1) • Nuclear Qualified Actuators (IEEE-382)

  39. Possible Nuclear Target Segment Strategies • Balance of Plant (BOP) only: Existing and New Build • Safety-Related: Existing plants (utility personnel) • Safety-Related: New build (NSSS, EPC, utility personnel) • Domestic Nuclear • International Nuclear The target segment will greatly dictate the degree of qualification required

  40. Nuclear Life Extension • Nuclear Plants were originally licensed for a 40-year life. • Nuclear Plants are receiving a 20-year life extension. • There are “life after 60” programs currently under way.

  41. Nuclear Life Extension • Major issues for POVs: • Obsolescence: replacement parts • Confirm original design considerations for pressure boundary: fatigue, erosion, corrosion, and embrittlement • Increase the required valve torque or thrust requirement to operate under worst-case conditions • Decrease the actuator capability

  42. Nuclear Life Extension • NRC and Industry have implemented aging-management programs: • In-service inspection (ASME Section XI) • In-service testing (ASME Operations & Maintenance Code, Periodic Verification Programs) • Maintenance Rule (10CFR50.65, RG1-160) • License Renewal Rule (10CFR54)

  43. Nuclear Life Extension-Opportunities • Replacement components or parts • Evaluation of original Code Design reports with respect to fatigue, corrosion, erosion, and embrittlement • Analysis and testing to qualify components for a longer life

  44. Conclusion • Requirements for the Nuclear Industry are unique and require a significant commitment • Use of rigorous test-based validated methods are required for Nuclear products. Experience-based methods are often suitable for other industries. • A judicious combination of validated first-principle analytical models and testing the is most effective approach for qualifying a product line. Contact information: nestep@kalsi.com

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