ermsar 2012, cologne march 21 – 23, 2012 pretest calculations of quench-debris-0 test using...

ERMSAR 2012, Cologne March 21 – 23, 2012

Pretest Calculations of QUENCH-DEBRIS-0 Test Using SOCRAT/V3 Code

VASILIEV A.D.

NUCLEAR SAFETY INSTITUTE OF RUSSIAN ACADEMY OF SCIENCES (IBRAE),

B.TULSKAYA 52, 115191 MOSCOW, RUSSIA


Content of Presentation

1. Purpose

2. QDEBRIS-0 Experiment Features

3. SOCRAT – Computer Modelling Code

4. SOCRAT Results of Modelling

5. Conclusions


Purpose

The QUENCH-DEBRIS-0 test is planned at QUENCH facility, KIT, Karlsruhe, Germany. The objective of this bundle test is the investigation of thermo-hydraulic, thermo-mechanical and physico-chemical phenomena under severe accident conditions with debris and melt pool formation.

The lessons learned from severe nuclear accidents at Three Mile Island, Chernobyl and Fukushima showed the very high importance of accident control measures to prevent the development of design basis accident to beyond design basis accident and to mitigate the consequences of beyond design basis accident.

The deep understanding of hydraulic, mechanical and chemical processes taking place under accident conditions is necessary, in particular, during late phase with debris formation.


Hafnia

QUENCH-DEBRIS-0 Features

Hafnium will be used in QDEBRIS tests


Hafnium-containing rocket nozzle of the Apollo Lunar Module


QUENCH-DEBRIS-0 Features

Hafnium-containing periphery rods, corner rods and shroud of QUENCH-DEBRIS facility


SOCRAT Computer Modelling Code

SOCRAT/V3

SOCRAT/V2

SOCRAT/V1


SOCRAT Nodalization Scheme for QUENCH-DEBRIS


SOCRAT: Debris Behaviour Module

Thermal Problem of SOCRAT Code

DEBRIS THERMAL HYDRAULIC MODULE

Debris solid and fluid oxidation

Calculation of thermo-physical

properties of debris solid/liquid phases

System solution (,s,,,,p) for new timestep

Calculation of debris materials relocation inside

debris and between debris and non-debris meshes

Geometry (topology) of debris from

formation criteria or input data

Matrix coefficients for conservation

equations


SOCRAT: Debris Behaviour Module Equations

1/ 2

ff ff f f f Ef f f f f f f

u u Cu p g u u u u

s t s s s K K

time convection pressure gravity Brinkmann Darcy Forchheimer

d diameter of particles3

22180(1 )

K d

permeability

2 3

2 216 (1 )h

K K fs

dK

k k A

2.5Kk

4

(1 )hfs

dA

hydraulic diameter EC Ergun constant


Energy Equations

ff f

f f f f d f f fus

s H pH u T H m s

t t

(1 )fs f f

sf sf s f nuc chh A T T q q fH sH Specific enthalpies

(1 )(1 ) (1 )

fs ss s s ss s s fus sf sf s f nuc ch

H pT H m h A T T q q

t t

fnucqfchq

d

internal heat generation rate due to fission products decay

internal heat generation rate due to chemical reactions

effective thermal conductivity due to hydrodynamic dispersion

ff eff

s f

ss eff

s f

effective solid thermal conductivity taking into account radiative heat transfer

effective solid thermal conductivity taking into account radiative heat transfer


Radiative Heat Transfer Modeling,g eff g rad effective conductivity of gas

34rad s BCa d T effective radiative conductivity

sa emissivity

C constant of the order of unity

B Stefan-Bolzman constant

, ,,

1

(1 )eff g eff g eff

g eff

sf

0.044

1.6

,

0.3 sf

g eff

1

g

sf volume-averaging conductivity of solid and liquid

ERMSAR 2012, Cologne March 21 – 23, 2012 Time, s

Temperature, K

1500

500

2500

Preliminary heat-up

Preoxidation

Finalheat-up

Cool-down

fast cool-down, water flood

slow cool-down, no water flood


Estimation of Melt Velocity Relocating Downward

ff

f f

K g Kgu

92.75 10K 6 21.0 10 /f m s

22.75 10 /fu m s

1 5 /fu mm s

Kozeny constant

Account of relative permeability


Basic Thermo-Physical Corium Parameters

3 35.4 10 0.2 10 (2 1)

5 58.8 10 0.2 10 (2 1)

7.5 5 (2 1)

0.57

2 2

2 2

/

/ /ZrO ZrO

ZrO ZrO Zr Zr

M m

M m M m

Pa·s, dynamic viscosity

K-1, volumetric expansion

W/(mK), thermal conductivity

N/m, surface tension

Zr oxidation extent


QUENCH-DEBRIS-0:Calculated Temperature

Behaviour

Maximum temperature is about 2500K

The first heat-up phase and preoxidation phase are similar to classical QUENCH-06 test!


QUENCH-DEBRIS-0: Proposed Total Electric Power

0 1000 2000 3000 4000 5000T im e, s

0

10000

20000

30000

40000

50000

Pow

er, W

Q U E N C H -0 2

Q U E N C H -03

Q U E N C H -0 9


QUENCH-DEBRIS-0: Chemical Reactions

Zr + 2H2O = ZrO2 + 2H2 + Q1

Zr + O2 = ZrO2 + Q2

yes

no

yesHf + 2H2O = HfO2 + 2H2 + Q3

Q1 =6.45 106 J/kg Zr

Q2 =12.0 106 J/kg Zr

Q3 =2.6 106 J/kg Hf


E-110 (Zr1%Nb) Oxidation Rate

KtW 2 weight gain, mg/cm2; K - rate constant, mg2/(cm4s)

RT

QAK exp Q - activation energy, J/mole; R – gas constant, J/(moleK); T – temperature,

K

tRT

QAKtW

2exp2/1

K=

T

23040exp1059.1 6

T

20800exp10825.9 5

T

20820exp10464.8 5

550C<T<1200C

1300C<T<1500C

1500C<T<1600C

Bibilashvili Yu.K., Sokolov N.B., Andreyeva-Andrievskaya L.N., Salatov A.V. High-Temperature Interaction of Fuel Rod Cladding Material (Zr1%Nb Alloy) with Oxygen-Containing Mediums. IAEA-TECDOC-921, Dimitrovgrad, 1995, p.117-128.


QUENCH-DEBRIS-0:Hafnium Oxidation Rate

K = 0.76 kg/(m2s1/2)

Ea = 78423 J/mole

Steinbrueck et. al. High-Temperature oxidation and quench behaviour of Zircaloy-4 and E110 cladding alloys. Progress in Nuclear Energy, 52(2010), pp. 19-36.

Hafnium oxidation rate is several times lower!


QUENCH-DEBRIS-0: Calculated Heat Balances in Core

0 2000 4000 6000 8000 10000Time, s

0

10000

20000

30000

Pow

er, W

Q electric core

Q coolant

Q shroud

Q chemical

1

2

34

1 – total electric power

2 – heat transferred by gas

3 – heat to shroud

4 – chemical power

All rods and shroud made of Zry!


QUENCH-DEBRIS-0: Calculated Electric Current and H2 Rate

Hydrogen generation rate


QUENCH-DEBRIS-0: Calculated Hydrogen Production

0 2000 4000 6000 8000 10000T im e, s

0

0.02

0.04

0.06

0.08

0.1

Hyd

roge

n p

rod

uct

ion

, kg

1

2

1 - total H2 release

2 - H2 release in debris

All rods and shroud made of Zry!


QUENCH-DEBRIS-0: Diminishing Steam Mass Flow Rate Leads to More Wide Axial Temperature Profile

Calculated Axial Distribution of Zirconia Layer Thickness

Discover new fundamental nature laws with QUENCH-DEBRIS!

This ambitious program will help in more realistic desription of debris-

related phenomena under NPP accident conditions!

LABORATORY

A fast heat-up rate scenario after pre-oxidation is proposed to get massive high temperature porous debris and pool zone during QDEBRIS-0 test.

Application of Hafnium instead of Zircaloy leads to more manoeuvrable and flexible experiment control.

Conclusions

SOCRAT code was used to estimate basic parameters of the test.

Such important issues as debris oxidation and relocation phenomena, debris hydraulics as well as the coolability of massive debris bed can be investigated.

-5 s-4 s-3 s-2 s-1 s 0 s

ermsar 2012, cologne march 21 – 23, 2012 pretest calculations of quench-debris-0 test using...

Documents

debris oxidation

debris hydraulics

realistic desription

related phenomena

relocation phenomena

laboratorya fast heat

npp accident conditions

pool zone