ML033450382
| ML033450382 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 06/16/2003 |
| From: | FirstEnergy Nuclear Operating Co |
| To: | Office of Nuclear Reactor Regulation |
| Hopkins J | |
| Shared Package | |
| ML033450382 | List: |
| References | |
| Download: ML033450382 (57) | |
Text
Davis-Besse Nuclear Power Station Modification of High Pressure Injection Pumps 1
avis-Besse ar Power Station June 19, 2003
Agenda pening Remarks . . . . . . . . . . . Gary Leidich
- HPI Pump Design.. Jim Powers
- HPI Pump ModificationsBob Coward, MPR osing Comments.... Gary Leidich 2
avis-Besse ar Power Station June 19, 2003
Opening Remarks Gary Leidich Executive Vice President - FENOC 3
avis-Besse ar Power Station June 19, 2003
Overview
Background
-Implemented Building Block approach in the summer/fall of 2002 that included assuring the health of plant systems
-System Health Assurance identified the High Pressure Injection Pumps as an original design issue since fine particles from the Containment Emergency Sump could potentially damage the pumps during the loss-of-coolant accident (LOCA) recirculation mode
-Assessed the alternatives to address the issue Today
-Present resolution plan 4
avis-Besse ar Power Station June 19, 2003
Return to Service Plan Restart Overview Panel Reactor Head System Health Resolution Plan Assurance Plan Program Compliance Restart Test Plan Plan Restart Action Plan Management and Containment Health Human Performance Assurance Plan Excellence Plan 5
avis-Besse ar Power Station June 19, 2003
Desired Outcome
- An understanding by the NRC of the proposed High Pressure Injection Pumps modification and testing, and assurance that the pumps will perform their required safety functions 6
avis-Besse ar Power Station June 19, 2003
High Pressure Injection (HPI) Pump Design Jim Powers Director - Davis-Besse Engineering 7
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High Pressure Injection System Design Functions HPI System provides emergency functions as part of the mergency Core Cooling System
-Two redundant trains provide emergency core cooling for small break LOCA
-Operates in conjunction with Low Pressure Injection System and Core Flood Tanks to limit core damage in accordance with the requirements of 10CFR50, Appendix K for a range of small break LOCAs
-Provides borated water to decrease Reactor Coolant System (RCS) reactivity
-Provides makeup for reactor coolant contraction due to cooling of RCS 8
avis-Besse ar Power Station June 19, 2003
High Pressure Injection System Safety Functions arge-Break (LBLOCA)
-Borated Water Storage Tank (BWST) injection mode operation
-LBLOCA safety analyses do not credit HPI mall-Break (SBLOCA)
-BWST injection mode and Containment Emergency Sump recirculation mode operation
-Flow requirements from safety analyses oron precipitation control
-Containment Emergency Sump recirculation mode operation
-250 gpm required through Auxiliary Pressurizer Spray line Boron precipitation control 9
avis-Besse ar Power Station June 19, 2003
High Pressure Injection Pumps
- Manufacturer
- Babcock and Wilcox
- Type
- Horizontal, eleven stage centrifugal pumps
- 600 HP electric motors
- Hydrostatic bearing
- Design Pressure/Temperature
- 2000 psig/ 3000F
- Design/Manufacture Code
- ASME Pump & Valve Code, Class II, November 1968
- Surveillance Test/Inservice Testing
- Believed to be unique to Davis-Besse in domestic nuclear industry 10 avis-Besse ar Power Station June 19, 2003
HPI Pump Design Issues ost-LOCA Operation Issues
-In post-LOCA recirculation mode operation, HPI pump suction is from Containment Emergency Sump
-Sump is likely to contain debris from LOCA blowdown and containment spray actuation
-HPI Pumps must be capable of operating with debris in the pump flow 11 avis-Besse ar Power Station June 19, 2003
HPI Pump Design Issues ystem Health Assurance identified three design issues
-Hydrostatic bearing plugging
-Bearing orifices are smaller than emergency sump strainer and could become plugged
-Bearing pad clearances are smaller than sump strainer
-Fine clearance wear
-Preliminary rotordynamics analyses suggested increases in clearances due to wear by debris could lead to operation at critical speeds
-Increased clearances will degrade pump hydraulic performance
-Supply path to cyclone separator (seal water) could be smaller than sump strainer and may become plugged 12 avis-Besse ar Power Station June 19, 2003
HPI Pump Modification Objective Implement a resolution plan to resolve HPI pump debris issue that
-Modifies only the HPI pump
-Makes no substantive change to existing licensing basis, procedures, USAR, or design basis documents
-Makes no changes to Technical Specifications 13 avis-Besse ar Power Station June 19, 2003
High Pressure Injection (HPI) Pumps Design Issue Resolution Bob Coward MPR 14 avis-Besse ar Power Station June 19, 2003
Project Overview Issue
-Debris in containment emergency sump post-LOCA may degrade HPI pump performance
- Plugging of hydrostatic bearing orifice
- Plugging of hydrostatic bearing pads
- Wear of fine clearances 15 avis-Besse ar Power Station June 19, 2003
HPI Pump Internal Assembly Eleven stage internal assembly 16 Assembly Process avis-Besse ar Power Station June 19, 2003
4th Stage Volute 4th Stage Volute with Impeller 4th Stage Volute 17 Back Side of Volute with Impeller avis-Besse ar Power Station June 19, 2003
Hydrostatic Bearing Orifice Plugging Design issue
-Orifices in supply to hydrostatic bearing pads are 0.111 inch diameter
-New containment emergency sump strainer has 0.188 inch diameter openings
-Orifices may plug with debris that passed through sump strainer, degrading bearing performance Resolution
-Add a self-flushing strainer plate at entrance to bearing supply tube 18 avis-Besse ar Power Station June 19, 2003
Hydrostatic Bearing Pad Debris Design issue
-Bearing design includes tight clearances (0.012 inch to 0.015 inch diametral) at edges of hydrostatic bearing pads
-Debris in water flowing to bearing pads may be larger and accumulate in the bearing pad, impacting bearing performance
-Degradation of bearing performance may impact pump operation Resolution
-Demonstrate existing clearances are acceptable based on test of actual bearing with conservative debris loading 19 avis-Besse ar Power Station June 19, 2003
Hydrostatic Bearing Configuration 20 avis-Besse ar Power Station June 19, 2003
Hydrostatic Bearing Design 21 avis-Besse ar Power Station June 19, 2003
Fine Clearances Wear esign issue
-Pump design includes tight clearances
-Central volute bushing (0.011 inch to 0.014 inch diametral)
-Hydrostatic bearing (0.012 inch to 0.015 inch diametral)
-Wear rings (0.019 inch to 0.021 inch diametral)
-Debris in water may increase rate of wear of the fine clearances
-Increased clearances could result in operation at critical speeds
-Increased clearances could decrease hydraulic performance capability esolution
-Use analysis, mock-up, and in-plant testing to demonstrate reliable pump operation with expected increased clearances 22 avis-Besse ar Power Station June 19, 2003
Cyclone Separator Supply Line Plugging ostulated design issue
-New containment sump strainer has 0.188 inch diameter openings
-Supply line to the cyclone separator was considered to be as small as ~ 0.125 inch diameter
-Supply line may plug with debris that passed through sump strainer, starving flow to the cyclone separator and seal esolution
-Updated information shows supply line is ~ 0.35 inch diameter, but cyclone separator inlet port is 0.180 inch diameter
-Potential need for cyclone separator modification or replacement under consideration (pump modifications not necessary) 23 avis-Besse ar Power Station June 19, 2003
Resolution Approach
- Modifications
-Install self-flushing strainer on volute to prevent plugging of hydrostatic bearing supply line orifice
-Move supply line take-off on volute
- Analysis
-Rotordynamic analysis to demonstrate satisfactory pump operation with increased fine clearances
-Hydraulic analysis to demonstrate satisfactory pump performance with increased fine clearances 24 avis-Besse ar Power Station June 19, 2003
(Continued)
Perform mock-up testing of
-Strainer installation to confirm self-flushing nature and debris dispersal effect
-Hydrostatic bearing under debris loading to confirm satisfactory operation
-Fine clearances to determine wear rates Perform in-plant testing to
-Validate rotordynamics model
-Validate hydraulic performance model
-Demonstrate satisfactory pump operation with increased clearances Perform post-modification testing to confirm pump operation 25 avis-Besse ar Power Station June 19, 2003
Pump Modification Modification
-Install strainers over the hydrostatic bearing supply ports in volute
-Relocate hydrostatic bearing supply ports to increase flow velocity over strainer and reduce debris entering hydrostatic bearing
-Perform all design and modification activities as safety related Design analyses
-Perform stress analysis of modified volute and strainer
-Perform hydraulic analysis of hydrostatic bearing flow path
-Perform Computational Fluid Dynamics (CFD) analyses to support moving take-off port 26 avis-Besse ar Power Station June 19, 2003
Original Strainer Concept 27 avis-Besse ar Power Station June 19, 2003
Final Strainer Design 28 avis-Besse ar Power Station June 19, 2003
Volute Finite Element Model 29 avis-Besse ar Power Station June 19, 2003
Finite Element Analysis Results 30 avis-Besse ar Power Station June 19, 2003
Hydrostatic Bearing Flow 31 avis-Besse ar Power Station June 19, 2003
Pump Guinard Testing ench PWRs use similar class pump for makeup/HPI
-Normal service instead of standby
-12 stages instead of 11 stages
-4500 rpm instead of 3600 rpm
-Central hydrostatic bearing instead of bushing uclear Safety Authority requested validation pumps would erate satisfactorily in emergency conditions
-Testing performed in 1980-1981 ump operated satisfactorily after hydrostatic bearing supply rt was moved to side of volute near impeller 32 avis-Besse ar Power Station June 19, 2003
Analyses otordynamics Analysis
-Model tuned using vibration data from 1X in-plant test
-Preliminary model predictions show vibration levels for increased fine clearances (up to 2X) are acceptable and not significantly greater than 1X levels ydraulic Analysis
-Model considers leakage between stages across wear rings
-Calculations performed for 2X fine clearance condition
-Predicted performance for 2X meets surveillance test requirements 33 avis-Besse ar Power Station June 19, 2003
Rotordynamics Analysis 34 avis-Besse ar Power Station June 19, 2003
Hydraulic Performance Analysis 35 avis-Besse ar Power Station June 19, 2003
Mock-Up Testing
- Test objectives
-Confirm strainer self-flushing behavior
-Confirm hydrostatic bearing operation
-Measure wear ring clearance increases
-Measure central volute bushing clearance increases
-Measure hydrostatic bearing clearance increases
-Measure debris separating effect by pump impellers 36 avis-Besse ar Power Station June 19, 2003
Mock-Up Testing
- All tests
-Fixture design matches critical characteristics of HPI pump
-Performed in accordance with QA Program requirements
-Debris characterization based on Davis-Besse containment design
-Full scale components
-Capability to adjust clearances
-Capability to pause/re-start test for interim results 37 avis-Besse ar Power Station June 19, 2003
Debris Characterization
- HPI pump debris loading based on
-LBLOCA scenario
-Sump strainer size
-Mass and density of particles
-Flow velocities in containment
- Debris solution includes
-Fibrous insulation
-Rust particles
-Qualified and unqualified coatings
-Dirt and dust
-Concrete particles 38 avis-Besse ar Power Station June 19, 2003
Debris Characterization (Continued) pproach
-Analyses based on debris generation and debris transport analyses for Davis-Besse containment sump, as well as NRC-sponsored research
-Critical parameters, and their acceptance ranges, are defined for each debris type
-Commercial-off-the-shelf (COTS) materials selected to match critical characteristics
-Commercial dedication performed to qualify COTS materials
-Debris handling procedure addresses initial loading, sampling, and re-loading 39 avis-Besse ar Power Station June 19, 2003
Debris Acceptance/Inspection 40 avis-Besse ar Power Station June 19, 2003
Debris Acceptance/Inspection (Continued) 41 avis-Besse ar Power Station June 19, 2003
Debris Characterization (Continued) onservatisms
-75% of generated debris transports to HPI pump
-No credit for filtering of small debris on sump strainer surfaces
-Particle/fiber sizes biased toward increasing potential for pump degradation
-All hard concrete debris is considered transportable and in size range with potential to wear critical pump surfaces 42 avis-Besse ar Power Station June 19, 2003
Mock-Up Testing ve test loops
-Loop 1 - Suction Wear Ring
-Loop 2 - Discharge Wear Ring
-Loop 3 - Hydrostatic Bearing
-Loop 4 - Central Volute Bushing
-Loop 5 - Hydrostatic Bearing Supply Strainer 43 avis-Besse ar Power Station June 19, 2003
Suction Wear Ring Fixture 44 avis-Besse ar Power Station June 19, 2003
Suction Wear Ring Fixture (Continued) 45 avis-Besse ar Power Station June 19, 2003
Suction Wear Ring Fixture (Continued) 46 avis-Besse ar Power Station June 19, 2003
Suction Wear Ring Fixture (Continued) 47 avis-Besse ar Power Station June 19, 2003
Discharge Wear Ring Fixture 48 avis-Besse ar Power Station June 19, 2003
Mock-Up Testing 49 avis-Besse ar Power Station June 19, 2003
Mock-Up Testing (Continued) 50 avis-Besse ar Power Station June 19, 2003
In-Plant Testing
- Baseline pump test (1X)
-Conducted during surveillance test
-Increased data acquisition capability
-Results used to validate rotordynamics model
- Increased response at 942 gpm
- Low vibratory response throughout flow range 51 avis-Besse ar Power Station June 19, 2003
(Continued)
- Worn pump test (2X)
-Spare pump assembled with 2X fine clearances
-Increased data acquisition capability
-Results used to validate rotordynamics model, validate hydraulic model, and demonstrate pump operation is acceptable
- Preliminary results show low vibratory response over full range of operating conditions
- Preliminary results show hydraulic performance acceptable
- Most importantly - pump ran well with clearances opened to twice normal
- Post-modification testing will be performed to demonstrate satisfactory operation of modified pumps 52 avis-Besse ar Power Station June 19, 2003
Failure Mode and Effects Analysis
- Failure Mode and Effects Analysis in progress as design activity
- Strainer design includes full penetration groove welds on three sides, fillet weld on fourth side
- Expected result is no increase in probability of failure 53 avis-Besse ar Power Station June 19, 2003
Status
- Modification design
-Design complete and in review
-10CFR 50.59 evaluation in progress
-Long lead parts/material on order
- Mock-up testing
-Debris characterization complete
-Fixture design and fabrication complete
-All test loops operating earlier this week
-Complete confirmatory tests this week
-Complete wear tests in July 54 avis-Besse ar Power Station June 19, 2003
(Continued)
Rotordynamic analysis
-Preliminary model completed
-Benchmarking in progress using results of in-plant tests Hydraulic analysis
-Preliminary model/calculation completed
-Final calculation in preparation based on in-plant test results In-plant activities
-Baseline and worn pump tests completed
-Both pumps removed and at fabricator for modification
-Pump re-installation planned for mid-July 55 avis-Besse ar Power Station June 19, 2003
Summary Modifications and associated analysis and testing are expected to fully resolve debris issue Current schedule shows completion to support normal operating pressure test in July 56 avis-Besse ar Power Station June 19, 2003
Closing Comments Gary Leidich Executive Vice President - FENOC 57 avis-Besse ar Power Station June 19, 2003