forschungszentrum karlsruhe in der helmholtz-gemeinschaft fzk, h & hqws11, ka, 25.-27.10.2005 1...
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Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft FZK, H & HQWS11, KA, Control Rod Damage and Degradation Main Results (QWS10) CR fails –near upper end of heated zone –near end of first transient –in two steps Clad (Q-7/-9: Δt = 33 s) Guide tube (Δt = 196 s) Subsequent test conduct/ development different Steam starvation significant test parameter Sequence diagram established, necessary for model development CR degradation is embedded in general bundle damage and degradation B 4 C Contribution to Oxidation (1) Analysis based on MS data Analysis is global assessment Basis B 4 C + 7 H 2 O 2 B 2 O 3 + CO + 7 H 2 – 760 B 4 C + 8 H 2 O 2 B 2 O 3 + CO H 2 – 792 B 4 C + 6 H 2 O 2 B 2 O 3 + CH H 2 – 987 Zr + 2 H 2 O ZrO H 2 – 595 Restrictions Analysis uncertain in late phase (further chem / phys phenomena) MS based on mass numbers Deduction of chemical compounds ambiguous B 4 C oxidation probably in smaller bundle region than Zr oxidationTRANSCRIPT
Forschungszentrum Karlsruhein der Helmholtz-Gemeinschaft
FZK, H & H QWS11, KA, 25.-27.10.2005 1
Analysis and Comparison of Experimental Data of QUENCH-07 to QUENCH-09
Review and Progress
Ch. Homann, W. Hering
Forschungszentrum KarlsruheP.O. Box 3640
D-76021 Karlsruhe, Germany
11th International QUENCH Workshop
Forschungszentrum Karlsruhe25-27 October 2005
Forschungszentrum Karlsruhein der Helmholtz-Gemeinschaft
FZK, H & H QWS11, KA, 25.-27.10.2005 2
Introduction
• QUENCH-07 – QUENCH-09– devoted to B4C control rod behaviour– cover wide range of accident conditions (LOOP / LOCA)
• Several aspects presented at previous QWSs– CR behaviour– General findings
• Time for an state of the art overview– Totally based on experimental on-line data– Demonstrates their value as “stand alone” information– Further work possible and appreciated
• Report FZKA 7101 in work
Forschungszentrum Karlsruhein der Helmholtz-Gemeinschaft
FZK, H & H QWS11, KA, 25.-27.10.2005 3
Control Rod Damage and DegradationMain Results (QWS10)
• CR fails– near upper end of heated zone– near end of first transient– in two steps
Clad (Q-7/-9: Δt = 33 s) Guide tube (Δt = 196 s)
• Subsequent test conduct/ development different
• Steam starvation significant test parameter
• Sequence diagram established,necessary for model development
• CR degradation is embedded in general bundle damage and degradation
B4C Contribution to Oxidation (1)
Analysis based on MS data Analysis is global assessment
BasisB4C + 7 H2O 2 B2O3 + CO + 7 H2 – 760B4C + 8 H2O 2 B2O3 + CO2 + 8 H2 – 792 B4C + 6 H2O 2 B2O3 + CH4 + 4 H2 – 987
Zr + 2 H2O ZrO2 + 2 H2 – 595
Restrictions• Analysis uncertain in late phase
(further chem / phys phenomena)• MS based on mass numbers
Deduction of chemical compounds ambiguous
• B4C oxidation probably in smaller bundle region than Zr oxidation
Forschungszentrum Karlsruhein der Helmholtz-Gemeinschaft
FZK, H & H QWS11, KA, 25.-27.10.2005 4
B4C Contribution to Oxidation (2)
Forschungszentrum Karlsruhein der Helmholtz-Gemeinschaft
FZK, H & H QWS11, KA, 25.-27.10.2005 5
Material Relocation
Basis• MR normally detected in PTE• Guide tube failure Q-7/-9: 2136 / 2590 s
(1896 / 2125 s into first transient)• Absorber melt at low temperature
TCs may indicate MR
Results• Wide axial & radial spreading• Effects confirmed by PTE• Number of detected events not
representative for total number• Additional phenomena in later test
phases interpretation difficult• Similar results in QUENCH-09 in spite
of different test conduct
Forschungszentrum Karlsruhein der Helmholtz-Gemeinschaft
FZK, H & H QWS11, KA, 25.-27.10.2005 6
First Transient (1)
Experimental findings• Heat-up rates quite close together• But: CR degradation different
Closer look at tests helpful?
Differences between tests• Test conduct
– Steam: 3.0, 3.15, 3.4 g/s– Initial bundle temperatures– Radial heat losses
• Further differences– Geometry tolerances – Assembly tolerances– Other items
Forschungszentrum Karlsruhein der Helmholtz-Gemeinschaft
FZK, H & H QWS11, KA, 25.-27.10.2005 7
First Transient (2)
Results• More than one reason for
differences• Effects
– may be localized– may compensate one another
Consequences• Heat-up time within ±5 %• Margin measure for bandwidth
(facility, test conduct)• Much more tests needed
for proper statistics…
Forschungszentrum Karlsruhein der Helmholtz-Gemeinschaft
FZK, H & H QWS11, KA, 25.-27.10.2005 8
Second Transient in Q-07/-08Experimental findings
Differences in test conduct sum up with time, but
• Bundle conditions similar at start of second transient (T2)
• Test conducts of T2 similar
ProblemH2 production very different
SolutionSee figure
Consequences• Direct comparison of test results
impossible • Pay special attention on duration of
hot phase of T2, if good agreement of tests required
Forschungszentrum Karlsruhein der Helmholtz-Gemeinschaft
FZK, H & H QWS11, KA, 25.-27.10.2005 9
Cool-Down PhaseExperimental findings in Q-07• Shroud failure at 3486 s• TCI 15/0 always below Tsat
• Fast final decrease of TSH/TCI• Pressure signals not helpful
Results• Condensation in annulus• Steam mass flow rate decreases in
upper part of bundle measured rate valid for bundle exit
• Radial heat flux reversed during c/d• Large azimuthal asymmetry even in
cooling jacket• Maximum temperature in c/j later at
lower elevations• Similar results for QUENCH-09• Premature end of data acquisition in
QUENCH-08
Forschungszentrum Karlsruhein der Helmholtz-Gemeinschaft
FZK, H & H QWS11, KA, 25.-27.10.2005 10
Delay of H2 Production in Cool-Down Phase of QUENCH-07
Problems
• Time synchronization of PCs diverged
• Condensation in steam feed pipe
• Solution difficult(MS sampling freq small)
Common Recommendations
• Synchronization based on P 411 (rod pressure)
• Time shift MS 15 … 21 s
• Delay H2 rate 5 … 7 s
Recommendations• Distributed by E-mail• Included in this presentation
Forschungszentrum Karlsruhein der Helmholtz-Gemeinschaft
FZK, H & H QWS11, KA, 25.-27.10.2005 11
MS Measurement Q-07Problem
• Consumed steam exceeds provided steam by up to ~50%
• Even higher peak measured with PRISMA
• Steam supply credible• Strong evaporation or
entrainment of condensate in steam feed pipe unlikely
• No physical explanation found
Transient MS tests in bundle necessary
Forschungszentrum Karlsruhein der Helmholtz-Gemeinschaft
FZK, H & H QWS11, KA, 25.-27.10.2005 12
Summary & ConclusionsCR behaviour
• Analysis of on-line data alone yields much insight
• Sequence of CR degradation understood
• CR failure in first transient• Large scatter for guide tube failure• CR contribution to oxidation
assessed roughly• Relocation of absorber melt
identified from TC readings
General outcome• Understanding of tests widely
extended• Work gives basis to model CR
degradation
Bundle behaviour
• Heat-up to ~ 1700 K: Δt/t = ±5 %; several reasons compete
• Reason for different hydrogen release in T2 of Q-7/Q-8 understood
• Thermal-hydraulic consequences of shroud failure investigated
• Q-7 data synchronisation corrected• Interpretation of MS signals in c/d
phase needs further work
General outcome• Direct comparison of test results
impossible due to differences in test conduct
• Only thorough and detailed work can give insight