Database Enhancements for Improved AREVA NP LWR Deposition Model BG Lockamon 11/17/ p.1

Transcription

1 Database Enhancements for Improved AREVA NP LWR Deposition Model BG Lockamon 11/17/ p.1

2 Database Enhancements for Improved AREVA NP LWR Deposition Model Brian G. Lockamon AREVA NP Inc., Plant Chemistry & Corrosion OLI Simulation Conference November 17, 2010

3 Acknowledgements AREVA NP Inc. Mike Pop Paul Sherburne OLI Systems, Inc. Andre Anderko Margaret Lencka Honggang Zhao Robert Young Chris Depetris James Berthold Jerzy Kosinski AQ Sim Pat McKenzie Database Enhancements for Improved AREVA NP LWR Deposition Model BG Lockamon 11/17/ p.3

4 Crud What is Crud? A colloquial term for corrosion and wear products (rust particles, etc.) that become radioactive (i.e., activated) when exposed to radiation. Because the activated deposits were first discovered at Chalk River, a Canadian nuclear plant, crud has been used as shorthand for Chalk River Unidentified Deposits. - U.S. NRC Glossary When used in this presentation, crud refers to corrosion products that accumulate on the nuclear fuel, are activated by the neutron flux in the core, and are transported throughout the reactor coolant. Database Enhancements for Improved AREVA NP LWR Deposition Model BG Lockamon 11/17/ p.4

5 Why Do We Care About Crud? Database Enhancements for Improved AREVA NP LWR Deposition Model BG Lockamon 11/17/ p.5

6 Consequences of Crud Fuel Failures Loss of first fission product barrier (through-wall corrosion of zirconium alloy fuel cladding) Increased noble gas releases and fission product contamination Potential mid-cycle shutdowns and extended outages ($$) Replacement fuel costs Operational Complications (Other Than Fuel Failures) Higher out-of-core dose rates and contamination Higher maintenance costs (more shielding & remote tooling required to reduce worker exposure) Reduced performance indicators Core power shift (in PWRs) caused by boron holdup in crud Increased fuel costs Potential for power reductions Database Enhancements for Improved AREVA NP LWR Deposition Model BG Lockamon 11/17/ p.6

7 Where We Are Today Update on AREVA BWR Crud Deposition Model Outline challenges with PWR chemistry modeling Summarize MSE Database enhancements for improved accuracy and utility under PWR conditions Example output from high-temperature metal solubility calculations Database Enhancements for Improved AREVA NP LWR Deposition Model BG Lockamon 11/17/ p.7

8 Boiling Water Reactors (BWRs) Database Enhancements for Improved AREVA NP LWR Deposition Model BG Lockamon 11/17/ p.8

9 BWR Reactor Water Conditions Pressure psi Temperature Coolant: ~285 C Fuel Rods: up to ~320 C Impurities Fe: ppb Cu: 1 5 ppb Silica: ppb Zinc 5 20 ppb Added for dose reduction Hydrogen ~100 ppb Added for corrosion prevention AREVA ATRIUM-10 Fuel Assembly Database Enhancements for Improved AREVA NP LWR Deposition Model BG Lockamon 11/17/ p.9

10 Conventional BWR Crud Modeling Tools Coupled to 1D T/H Model Off-Line Chemistry Model Solubility equations from fits of OLI Analyzer data First model developed by AREVA Utilized when calculation speed is essential On-Line OLI Analyzer Model Direct call of OLI Engine from MATLAB Developed in 2007 Utilized when greatest accuracy is desired Database Enhancements for Improved AREVA NP LWR Deposition Model BG Lockamon 11/17/ p.10

11 Utilization of Chemistry Model with CFD Current experience with BWR cores shows that more resolution is needed Crud deposition and failures occurring in areas not predicted by conventional models Coupling Chemistry Model with CFD used to predict both local and core-wide conditions Database Enhancements for Improved AREVA NP LWR Deposition Model BG Lockamon 11/17/ p.11

12 Local temperature distribution on fuel rods Accounts for flow patterns around spacer grids Allows for more accurate deposition modeling Prediction of deposit distribution in core becomes possible Particular attention paid to aggressive species like CuO and Zn 2 SiO 4 Allows identification of highestrisk fuel elements Operability assessment of changes in core design Example CFD-Chemistry Model Output Database Enhancements for Improved AREVA NP LWR Deposition Model BG Lockamon 11/17/ p.12

13 Pressurized Water Reactors (PWRs) Database Enhancements for Improved AREVA NP LWR Deposition Model BG Lockamon 11/17/ p.13

14 Typical PWR Reactor Coolant Conditions Parameter Concentration Range Notes Boron ppm Neutron Absorption Lithium 6 ppm ph Control ph 300 C Minimize Corrosion Dissolved Hydrogen cm 3 (STP)/kg H 2 O Suppress Radiolysis, Establish Reducing Environment Zinc 0 20 ppb Dose Reduction, Cracking Mitigation Corrosion Products (Fe, Ni, Cr) ppb Primarily Released from SG Tubing Temperature Range: 270 C 330 C Rod temperature approaches critical point of water RC Pressure: 15.6 MPa (~2250 psia) Database Enhancements for Improved AREVA NP LWR Deposition Model BG Lockamon 11/17/ p.14

15 ppm Li t/c PWR Challenges Boron Chemistry Previous database performed well at low temperatures but did not fit data at reactor coolant temperatures Problem complicated by incorrectly-reported poly-borate equilibrium coefficients in literature Revised database behaved well except for volatility 170 Solubility of boric acid in water Benrath, Blasdale and Slansky, Chanson and Millero Dukelski, McCulloch, Menzel, Nasini and Ageno, Nies and Hulbert, 1967 Table, ph=6.7 prediction, ph= Platford, 1969 Table, ph=6.8 prediction, ph= prediction, H3BO3 Table, ph=6.9 prediction, ph= Table, ph=7 prediction, ph=7.0 1 prediction, H2O w% H3BO3 Table, ph=7.1 prediction, ph=7.1 Table, ph=7.2 prediction, ph= Table, ph=7.3 prediction, ph= Table, ph=7.4 prediction, ph=7.4 ppm B Table, ph=7.5 prediction, ph= Database Enhancements for Improved AREVA NP LWR Deposition Model BG Lockamon 11/17/ p.15

16 t/c t/c PWR Challenges Boron Volatility At elevated pressure, boron concentration went through a maximum at ~ 353 C Apparently related to phase transition between H 3 BO 3 (aq), HBO 2 (aq), and B 2 O 3 (aq) at elevated temperature (where no data exists) OLI System adjusted fit in late 2009 to correct behavior p=153.1 atm liquid vapor Benrath, 1942 Blasdale and Slansky, 1939 Dukelski, 1906 McCulloch, 1937 Menzel, 1927 Nasini and Ageno, 1910 Nies and Hulbert, 1967 Platford, 1969 prediction, H3BO3 prediction, HBO2 prediction, B2O3 prediction, H2O B2O3+H2O w%b2o3 - liquid/vapor 40 w% B2O Database Enhancements for Improved AREVA NP LWR Deposition Model BG Lockamon 11/17/ p.16

17 PWR Challenges Temperature Deposition in PWRs primarily driven by local steaming (boiling) Steaming begins at C, depending on pressurizer pressure To model PWR deposition correctly, several additional hightemperature systems were needed H 3 BO 3 LiOH (already discussed) Fe O H Zn O H Ni O H NH 3 SiO 2 LiOH High-temperature (up to ~350 C) behavior of these systems developed by OLI Systems in 2009, released in yearly 2010 Database Enhancements for Improved AREVA NP LWR Deposition Model BG Lockamon 11/17/ p.17

18 PWR Model Current Status Currently using off-line model with fitted solubility relationships MATLAB connection to OLI Engine for PWRs needs to be developed Calculation time is an issue in PWR environments (more so than BWRs) Updated high-temperature metals data incorporated Primary species of interest: Fe 3 O 4, Ni, NiO, NiFe 2 O 4, ZnO, ZnFe 2 O 4, SiO 2, Zn 2 SiO 4 Incorporation of updates to H 3 BO 3 LiOH system in-progress Primary species of interest for power shift: Li 2 B 4 O 7 and LiBO 2 Completion in 2011 Database Enhancements for Improved AREVA NP LWR Deposition Model BG Lockamon 11/17/ p.18

19 Recent Work Ni Solubility at Elevated Hydrogen and ph PWR plants considering higher hydrogen levels Reduce crack propagation rate in Alloy 600 materials (e.g., nozzle penetration welds) Potential for inspection relief in future Demonstration plant also increasing coolant ph (calculated at 300 C) What are synergistic effects on Ni and Fe 3 O 4 solubility? Ni solubility decreases with increase in both H 2 and ph Potential to reduce Ni transport to core Database Enhancements for Improved AREVA NP LWR Deposition Model BG Lockamon 11/17/ p.19

20 Recent Work Fe 3 O 4 Solubility at Elevated Hydrogen and ph Magnetite solubility increases with increasing hydrogen Increase in solubility offset by increasing coolant ph Potential exists for increasing hydrogen without significantly affecting iron loading of core Database Enhancements for Improved AREVA NP LWR Deposition Model BG Lockamon 11/17/ p.20

21 What Does the Future Hold? Continue to work with OLI Systems to streamline PWR environment calculation Goal to significantly reduce calculation time Minimum acceleration of 2 3x needed On-line connection between MATLAB and OLI Engine for PWR environment Explore options to increase model temperature range Under thick deposit layers, temperatures approach critical point Database Enhancements for Improved AREVA NP LWR Deposition Model BG Lockamon 11/17/ p.21

22 Questions?