ML112070707
| ML112070707 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 07/26/2011 |
| From: | Letellier B, Sande T ALION Science & Technology Corp, Los Alamos National Laboratory |
| To: | Balwant Singal Plant Licensing Branch IV |
| Singal, B K, NRR/DORL, 301-415-301 | |
| Shared Package | |
| ML112070702 | List: |
| References | |
| TAC ME5358, GSI-191, TAC ME5359 | |
| Download: ML112070707 (74) | |
Text
Risk-Informed GSI-191 South Texas Project Models and Methods Used for CASA Grande Bruce Letellier Los Alamos National Laboratory Los Alamos, NM Tim Sande Alion Science and Technology Albuquerque, NM Risk-Informed GSI-191 Resolution NRC Public Meeting via Teleconference Tuesday, July 26, 2011 Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 1
Risk-Informed GSI-191 Overview Role of CASA Grande in risk-informed resolution of GSI-191 Complexities of Debris Generation, Transport, and Sump Blockage Strategies for Stochastic Modeling of DGTSB in CASA Required Inputs to CASA Grande Topical Approach and Implementation Plan
- Debris Generation
- Debris Transport
- Head Loss
- Air Intrusion
- Debris Bypass Interface With PRA July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 2
Risk-Informed GSI-191 ROLE OF CASA GRANDE IN RISK-INFORMED RESOLUTION OF GSI-191 July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 3
Risk-Informed GSI-191 Deterministic Resolution Path Characterized by systematic investigation of phenomenology
- Mostly separate effects moving towards integration
- Identification and good understanding of driving factors
- Wide improvements in plant configuration and safety posture (sump screen retrofits, plant cleanliness, etc.)
- Fragmented knowledge base
- Deterministic evaluation and test methods designed to separately prevent adverse conditions
- Focus on maximum exacerbation regardless of time-dependent interaction.
Adoption of physically contradictory conservatisms July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 4
Risk-Informed GSI-191 Risk-Informed Resolution Path Leverages NRC experience with PRA and IPE methodologies for prioritization of hazards and their commensurate mitigation Places deterministic assumptions in the context of a spectrum of possible break scenarios and their outcomes
- Does not eliminate consideration of deterministic conditions
- Spectrum of scenarios includes best estimate
- Spectrum defines relative likelihood of all many possible scenarios Introduces a plausiblity constraint for time-dependent precursors to extreme consequences July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 5
Risk-Informed GSI-191 Risk-Informed Resolution (contd)
Risk = Frequency x Consequence Consequence (plant performance) metrics are the same, but Risk requires consideration of frequency
- Initiating Event Frequency (# events/ROY) - time rate Used by PRA to assess contributions from many initiators
- Conditional Probability of physical conditions and outcomes Used in stochastic phenomenology to propagate variations in physical parameters to relative likelihood of scenario outcomes Estimation of realistic likelihood requires time-dependence July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 6
Risk-Informed GSI-191 Containment Accident Sequence Stochastic Analysis (CASA) Grande The purpose of CASA Grande is to representatively sample numerous possible break scenarios, determine the effects of each break on ECCS strainer and pump performance, and roll the analysis up into representative ECCS sump failure probabilities that can be passed to the PRA A time-dependent analysis approach will be used to track the outcome of each independent scenario Stochastic sampling methods will be used to sample parameter variability and compile distributions of plant performance metrics representing precursors to failure July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 7
Risk-Informed GSI-191 Role of CASA Grande Estimate sump failure probabilities for the PRA Small / Medium / Large LOCA Branches Provide a direct interface between complex phenomena affecting sump performance and PRA Incorporate variability in many factors to baseline plausible interactions Generate a spectrum of likely performance metrics with which to compare deterministic endpoints Capture explicit assumptions in a transparent approach that can be examined, debated, and easily modified Collapse inherently time-dependent phenomenology and system performance onto an inherently time-independent PRA July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 8
Risk-Informed GSI-191 Functionality of CASA Grande Complements PRA by combining
- 1. Plant geometry
- 2. Physics modules
- 3. Analytic approx and assumptions
- 4. Test data Explicit examination of accident phenomenology outside of PRA provides accessibility to subject matter experts Modular architecture driven by input files adds traceability and flexibility for individual plant applications Results focus on
- 1. Plant performance metrics directly tied to PRA branches and end-states
- 2. Sensitivity coefficients of physical parameters driving failure potential July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 9
Risk-Informed GSI-191 COMPLEXITIES OF DGTSB - REACTOR ACCIDENT PHENOMENA July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 10
Risk-Informed GSI-191 Accident Progression Overview SOLID COVER PLATE DEBRIS SCREEN TRASH RACK DEBRIS CURB SUMP STRAINER SUMP FLOOR July 26, 2011, NRC PreLicensing Meeting 01/27/2011 Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 11
Risk-Informed GSI-191 Complex Phenomenology A B C D E July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 12
Risk-Informed GSI-191 Complex Phenomena A
July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 13
Risk-Informed GSI-191 Complex Phenomena July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 14
Risk-Informed GSI-191 Complex Phenomena B
Transport Logic Diagram will be used to track and integrate all phases of debris transport July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 15
Risk-Informed GSI-191 Complex Phenomena C
July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 16
Risk-Informed GSI-191 Complex Phenomena D
July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 17
Risk-Informed GSI-191 Complex Phenomena E
Downstream effects not calculated in CASA Grande July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 18
Risk-Informed GSI-191 STRATEGIES FOR STOCHASTIC MODELING OF DGTSB IN CASA July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 19
Risk-Informed GSI-191 STP Key Attributes Favorable sump geometry prevents piling of large debris during fill up Three redundant trains opens options for a sacrificial strainer Directional vents to TSP baskets from common reactor cavity favors homogeneous mixing of fines, particulates, and degraded paint Large sump screen area prevents entrainment of large debris pieces during recirculation Dominant Nukon and TriSodium Phosphate minimize chemical effect concerns Dominant Nukon increases reliability of head-loss evaluation PCI Sure-Flow strainer with vortex suppression minimizes concerns for vortex ingestion July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 20
Risk-Informed GSI-191 Time-Dependent Performance Metrics Total Inventory Debris bed mass Unqual Coating Degradation Rate Suspended Fiber Concentration time trecirc Figure illustrates several types of function:
(1) Probability on a time point, (2) cumulative property, (3) time-dependent rate or conc Favorable geometry and small approach velocity justify first-order rate equations for pool concentration:
- Latent Debris / Fiber Fines / Eroded Large / ZOI Qualified Coating /
Unqualified Coating Semianalytic solutions for a variety of source descriptions (including instantaneous) enables discussion of relative timing for debris sources July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 21
Risk-Informed GSI-191 Time-Dependent Containment Params (Cold-Leg DEGB in Large Dry Contain)
MELCOR 1.8.5 customization of Indian Point 3, Westinghouse 4-loop Scaled using STP volumes, RWT capacity, etc.
Figures from NUREG CR\6770 July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 22
Risk-Informed GSI-191 Basic Probability Descriptions Prob of Failure July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 23
Risk-Informed GSI-191 Time-Dependent Failure Probability f(x) magnitude of x ro ba bil ity ep fai lur threshold time Vertical axis reports the probability density of perform metric x Receeding axis reports magnitude of the performance metric (how big?, how much?, how fast?)
Threshold defines a performance goal like NPSHmargin Parameter variations define fraction of cases exceeding threshold July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 24
Risk-Informed GSI-191 Tracking Time-Dependence
- 1. Containment pressure 7. NPSH (combines metrics)
- 2. Pool temperature 8. Header void fraction
- 3. Pool depth 9. Header water level
- 4. Bed composition 10. Vortex indicators
- 5. Bed head loss 11. Total volumetric sump flow (requires pump curves - not
- 6. Suspended concentration first year)
- 1. Fiber fines and small
- 2. Latent particulate
- 3. Damaged qualified coating
- 4. Unqualified coatings July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 25
Risk-Informed GSI-191 Propagation of Variability
[
P L = A(t ) (T (t ))V + B(t ) (T (t ))V 2 ]
P Differential head loss enables layered arrival and distributed compressibility Key assumption for head loss evaluation is that contiguous bed always yields higher head loss than discontiguous coverage Neglect two-phase head-loss in bed during first year July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 26
Risk-Informed GSI-191 CASA Grande Random Factors ZOI Sump Performance
- DEGB (yes/no - determined by
- Alternate train configurations (w and presence of whip restraint) wo spray)
- Jet geometry
- Deareation w.r.t. void ingestion Sphere with or without truncation
- Time-dependent bed accumulation Cone or oblate correlation w/wo truncation
- Azimuthal direction based on flow rate and pool Whip trajectories for DEGB concentration (100% filter for P)
- Debris
- Bypass based on observed testing Determined directly by impingement geom Compiled in advance for each break Containment location
- P and T histories for prototype LOCAs Transport
- Assumed degradation history for unqualified coatings
- Credit for grating relative to location
- Latent Debris loading
- Homogeneous distribution of small/fine, paint and particulates July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 27
Risk-Informed GSI-191 Performance Metrics CASA compiles statistical distributions of physical precursors to sump failure
- NPSHavail
- Bypass debris mass
- Air ingestion (deareation, boiling, vortexing)
- Flow obstruction (would require pump curves)
Definition of failure criteria will be adopted later
- Possible to assign distributions to the criteria for joint integration with the performance metrics July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 28
Risk-Informed GSI-191 Continuous Scenarios Lie in Prob Space Break Sump Transport Containment DownStream Phenomena Performance Random combinations of key parameter values define unique scenarios Scenarios can be sorted by attributes to determine risk drivers
- plant system, break location, debris volume, debris type, sump status, etc.
A very large number of scenarios will be evaluated to assess failure probability
- Unique state-vector i.d. allows post-processor sorting and analysis of failure probability drivers July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 29
Risk-Informed GSI-191 REQUIRED INPUTS TO CASA GRANDE July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 30
Risk-Informed GSI-191 Debris Generation Containment geometry Pipe break (LOCA) frequencies ZOI size/shape for plant materials Debris characteristics for plant materials Unqualified coatings quantity Qualified coatings quantity for LOCA categories Latent debris quantity Miscellaneous debris quantity July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 31
Risk-Informed GSI-191 Chemical Product Generation None required for initial quantification effort July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 32
Risk-Informed GSI-191 Debris Transport Blowdown transport fractions for LOCA categories Washdown transport fractions for LOCA categories Pool fill transport fractions for LOCA categories Recirculation transport fractions for LOCA categories Fiberglass erosion fractions for non-transporting pieces of debris No inputs required for upstream blockage in initial quantification July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 33
Risk-Informed GSI-191 Head Loss Strainer area/geometry Flow rate ECCS/CS pump NPSH margin July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 34
Risk-Informed GSI-191 Air Intrusion Vortexing
- Flow conditions (water level and flow rate) that would result in vortexing based on prototypical strainer testing (may not be an issue for PCI Sure-Flow design)
Gas desorption
- Containment pressure
- Containment pool temperature
- Strainer submergence depth July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 35
Risk-Informed GSI-191 Debris Bypass None required for initial quantification effort.
July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 36
Risk-Informed GSI-191 TOPICAL APPROACH AND IMPLEMENTATION PLAN July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 37
Risk-Informed GSI-191 Debris Generation Calculations CASA Grande will calculate debris quantities generated within given ZOIs for:
- Multiple break locations (welds on RCS pipes, wall rupture)
- Multiple break sizes at each location (2 to DEGB)
- Multiple jet orientations (if a non-spherical ZOI is used)
- Each type of insulation material in the vicinity of the break July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 38
Risk-Informed GSI-191 Input for Containment Geometry Import containment geometry from CAD model
- Concrete walls (robust barriers) imported using STL files
- Piping insulation imported through text files
- Equipment insulation recreated using primitive shapes
- Weld locations imported through text files July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 39
Risk-Informed GSI-191 CASA Grande Prototype July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 40
Risk-Informed GSI-191 Input for LOCA Frequencies Import LOCA frequency curves for each weld or other potential break location July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 41
Risk-Informed GSI-191 Normalized Freq Conditional Prob CASA Grande will only sample conditional probabilities Epistemic uncertainties on break frequency can be propagated if needed but no further epistemic factors will be segregated July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 42
Risk-Informed GSI-191 Input for ZOI Sizes and Shapes Define ZOI size and shape for each insulation material Spherical ZOI ANSI Jet ZOI Insulation Debris Insulation Debris Volume = 13.4 ft3 Volume = 10.2 ft3 July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 43
Risk-Informed GSI-191 Implementation Plan for ZOIs Plan for initial quantification effort:
- Use standard spherical ZOIs
- Use standard ZOI sizes (i.e. 17D ZOI for Nukon) scaled to appropriate break sizes Options for 2012 refinements:
- Modify ZOI shape using ANSI jet model, results of CFD modeling, etc.
- Modify ZOI size using PWROG blast testing, more realistic interpretation of AJIT data, CFD 17-D ZOI for 31 DEGB at STP encompasses approximately modeling, etc. half of Nukon insulation in SG compartments July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 44
Risk-Informed GSI-191 Input for Debris Characteristics Input appropriate debris characteristics:
- Insulation size distribution (fines, small pieces, large pieces, intact blankets)
- Coatings size distribution (particulate, chips)
- Latent debris distribution (fiber, particulate)
- Bulk and material densities for debris
- Characteristic size of fine material July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 45
Risk-Informed GSI-191 Implementation Plan for Characteristics Plan for initial quantification effort:
- Use NEI 04-07 baseline size distribution (fines and large)
- Assume all unqualified coatings fail as 10 micron particulate
- Use standard NEI 04-07 guidance for size and density Options for 2012 refinements:
- Alion refined size distribution (fines, small, large, and intact)
- Partial unqualified coatings failure based on EPRI report Proprietary Alion debris size distribution methodology is used to determine quantity of fines, small pieces, large pieces, and
- Unqualified epoxy fails as chips intact blankets based on distance of insulation from the break based on CPSES report July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 46
Risk-Informed GSI-191 Input for Unqualified Coatings Input unqualified coatings debris quantity:
- Epoxy, IOZ, phenolic, alkyd, baked enamel Generic example of unqualified coatings debris following a DBA test July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 47
Risk-Informed GSI-191 Input for Qualified Coatings Input qualified coatings debris quantity for bounding LBLOCA:
- Total quantity of 586 lbm based on STP debris generation calculation
- Epoxy, IOZ, Polyamide Primer Options for 2012 refinements:
- Calculate bounding coatings quantities for various LOCA categories (i.e. large, medium, and small breaks)
Blast testing of qualified coatings system July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 48
Risk-Informed GSI-191 Input for Latent Debris Input latent debris quantity:
- Total quantity of 200 lbm based on STP debris generation calculation
- 85% dirt/dust, 15% fiber Generic example of latent debris collected from containment July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 49
Risk-Informed GSI-191 Input for Miscellaneous Debris Input miscellaneous debris quantity:
- Total quantity of 100 ft2 based on STP debris generation calculation
- labels, tags, plastic signs, tie wraps Generic examples of labels and tie wraps July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 50
Risk-Informed GSI-191 Chemical Product Generation Calculations If necessary, CASA Grande will automatically calculate chemical debris quantities generated based on:
- Quantity of fiberglass debris in containment pool
- Quantity of aluminum or other chemically reactive materials exposed to sprays or submerged in the pool
- Buffer type and time dependent pH in containment pool
- Time dependent temperature in containment pool July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 51
Risk-Informed GSI-191 Input for Chemical Products
- Plan for initial quantification effort:
- Assume negligible impact from chemical effects for STP based on initial review of applicable ICET results
- Options for 2012 refinements:
SEM photo from ICET Test #2 (TSP with Fiberglass)
- Implement WCAP-16530 method if it is determined not to be overly conservative for STP
- Implement alternative method depending on approach used to account for chemical effects on the debris bed head loss Generic example of chemical goo produced using July 26, 2011, NRC PreLicensing Meeting WCAP-16530 recipe Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 52
Risk-Informed GSI-191 Debris Transport Calculations CASA Grande will use logic trees to calculate debris transport fractions with branches for:
- Blowdown transport
- Washdown transport
- Pool-fill transport
- Recirculation transport
- Erosion July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 53
Risk-Informed GSI-191 Implementation Plan for Blowdown Plan for initial quantification effort:
- Assume 100% of fine/small debris blown to pool
- Assume large pieces retained on grating based on STP debris transport calculation Options for 2012 refinements:
- Refine blowdown calculations based on drywell debris transport study (DDTS) and other methods July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 54
Risk-Informed GSI-191 Implementation Plan for Washdown Plan for initial quantification effort:
- Assume 100% of fine/small debris washed to pool
- Assume large pieces retained on grating based on STP debris transport calculation Options for 2012 refinements:
- Refine washdown calculations based on drywell debris transport study (DDTS) and other methods July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 55
Risk-Informed GSI-191 Implementation Plan for Pool-Fill Plan for initial quantification effort:
- Assume 100% of small debris remains in active pool
- Assume fine debris transports with flow (small amount transported to strainer and inactive regions)
Options for 2012 refinements:
- Perform CFD analysis to more accurately quantify pool-fill transport for small pieces of debris July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 56
Risk-Informed GSI-191 Implementation Plan for Recirculation Plan for initial quantification effort:
- Assume 100% transport of debris in active recirculation pool Options for 2012 refinements:
- Perform additional CFD runs to address realistic flow conditions (water level and flow rate)
- Modify assumed debris distribution
- Modify conservative transport metrics
- Incorporate time dependence in the transport analysis July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 57
Risk-Informed GSI-191 Implementation Plan for Erosion Plan for initial quantification effort:
- Assume 1% spray erosion for small and large fiberglass debris held up on gratings above containment pool
- Erosion for non-transporting small fiberglass debris in pool is N/A since this debris is all assumed to transport Options for 2012 refinements:
- Apply proprietary Alion erosion test results for realistic recirculation pool erosion fraction Setup for Alion fiberglass erosion test with filter in flume suction pipe July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 58
Risk-Informed GSI-191 Implementation Plan for Upstream Blockage One of the four 30 inch vent holes Plan for initial quantification in STP secondary shield wall effort:
- Assume negligible based on STP debris transport calculation Options for 2012 refinements:
- Further evaluate potential for upstream blockage and any uncertainties associated with the current analysis One of the two 6 inch drains in STP refueling canal July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 59
Risk-Informed GSI-191 Head Loss Calculations CASA Grande will use a correlation to determine head loss over the range of relevant conditions:
- Strainer geometry
- Debris loads Fiber Particulate Microporous Chemical
- Flow rate
- Temperature
- NPSH margin July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 60
Risk-Informed GSI-191 Implementation Plan for Head Loss Correlation Plan for initial quantification effort:
- Use NUREG/CR-6224 correlation for fiberglass, particulate, and chips
- Assume microporous debris (minimal at STP) behaves similar to other particulate
- Assume chemical debris has negligible impact on head loss
- Assume uniform debris deposition and flow through strainer Options for 2012 refinements:
- Perform tests to validate and/or refine head loss correlation for STP:
Perform tank testing to determine head loss reduction from non-uniform deposition on a complex geometry strainer, etc.
Perform vertical loop testing to determine head loss characteristics for Microtherm, WCAP-16530 chemical debris surrogate, etc.
Perform integrated chemical effects tests to more accurately quantify chemical effects Develop a bump-up factor or correlation to account for chemical debris July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 61
Risk-Informed GSI-191 NUREG/CR-6224 Correlation NUREG/CR-6224 correlation was developed based on flat plate vertical loop head loss testing with Nukon, iron oxide sludge, and paint chips:
m H = 3 . 5 S V2 1 .5 m (1 + 57 ) U + 0 . 66 S 3
m V (1 m )
U 2 Lm Where:
H = head loss (ft-water)
Sv = surface-to-volume ratio of the debris (ft2/ft3)
= dynamic viscosity of water (lbm/ft/sec)
U = fluid approach velocity (ft/sec)
= density of water (lbm/ft3) m = mixed debris bed solidity (one minus the porosity)
Lm = actual mixed debris bed thickness (in)
= 4.1528x10-5 (ft-water/in)/(lbm/ft2/sec2); conversion factor for English units July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 62
Risk-Informed GSI-191 Strainer Geometry Input strainer area and gap dimensions based on strainer drawings Calculate average approach velocity based on total strainer area Calculate interstitial volume based on gap dimensions Calculate increased approach velocity for large debris loads based on circumscribed strainer area July 26, 2011, NRC PreLicensing Meeting Photos and layout of STP PCI strainer Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 63
Risk-Informed GSI-191 Strainer Debris Loads Use debris generation and transport calculations for quantity and characteristics of debris on strainer for each postulated break at STP:
- Fiberglass
- Coatings particulate/chips
- Microtherm
- Dirt/dust
- Miscellaneous debris
- Chemical debris Generic tank test showing a high fiber debris load July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 64
Risk-Informed GSI-191 Flow Rate and Temperature Input total flow rate through each ECCS strainer for the specific case analyzed (maximum of 14,040 gpm at STP based on 8,840 gpm for two HHSI pumps and two LHSI pumps plus 5,200 gpm through one CS pump)
Calculate debris accumulation on each strainer based on relative flow split Input pool temperature to determine fluid density and viscosity July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 65
Risk-Informed GSI-191 NPSH Margin Input NPSH margin for each safety injection and containment spray pump Compare calculated debris bed head loss to the pump NPSH margin to determine whether the pump would fail July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 66
Risk-Informed GSI-191 Time Dependence A number of parameters used to determine ECCS strainer head loss are time dependent:
- Unqualified coatings failure
- Chemical product generation
- Debris transport and accumulation
- Pool temperature Due to changes in pool temperature, NPSH margin is also time dependent Some aspects of time dependence will be factored into CASA Grande to avoid over-conservatisms July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 67
Risk-Informed GSI-191 Air Intrusion Calculations CASA Grande will use test results and correlations to determine conditions that result in vortexing and gas desorption, along with the corresponding void fractions Froude numbers will be calculated to determine whether gas bubbles would accumulate or be drawn into sump suction piping Void fractions will be evaluated to determine:
- Potential for gas binding of ECCS pumps
- Effect of void fraction on NPSH
- Reduced efficiency of pumps, heat exchangers, etc. due to void fraction and resulting effects on system performance July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 68
Risk-Informed GSI-191 Vortexing Air intrusion due to vortexing is not an issue for STP since strainer design and configuration (under bounding water level and flow rate conditions) preclude vortex formation Generic strainer vortex test July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 69
Risk-Informed GSI-191 Gas Desorption Gas desorption void fractions will be calculated based on the strainer head loss, pool temperature, strainer submergence, and containment pressure based on Henrys Law CG = K G (T ) PG Where CG = Saturation concentration of air KG = Henrys constant for air at a given temperature T = Temperature PG = Partial pressure of air July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 70
Risk-Informed GSI-191 Debris Bypass Calculations CASA Grande will calculate debris bypass quantities based on test data and flow conditions The bypass debris quantities will be an output of CASA Grande used as an input for downstream effects calculations July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 71
Risk-Informed GSI-191 Implementation Plan for Bypass Plan for initial quantification effort:
- Use correlation of fiber bypass vs. flow rate developed by Gil Zigler :
BPtotal (g) = 1.538
- Q (gpm)
Options for 2012 refinements:
- Conduct bypass testing to evaluate bypass over the range of flow and debris load conditions for STP July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 72
Risk-Informed GSI-191 INTERFACE TO PRA July 26, 2011, NRC PreLicensing Meeting Operated by Los Alamos National Security, LLC for the U.S. Department of Energys NNSA Slide 73
Risk-Informed GSI-191 CASA Interface to PRA Separate results will be compiled for each standard LOCA size (small, medium, large)
- Breaks below 2 diam will be assigned zero impact in the PRA
- All rupture opening sizes will be examined before binning