Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft FZK, H & HQWS11, KA, 25.-27.10.2005 1...

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


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


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


FZK, H & H QWS11, KA, 25.-27.10.2005 4

B4C Contribution to Oxidation (2)


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


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


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…


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


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


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


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


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

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Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft FZK, H & HQWS11, KA, 25.-27.10.2005 1...

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