0-*,pR RE4&

UNITED STATES "NUCLEAR REGULATORY COMMISSION

WASHINGTON, D.C. 20555-l001

May 13, 1998

MEMORANDUM TO: Michael E. Mayfield, Chief Electrical, Materials and Mechanical Engineering Branch Office of Nuclear Regulatory Research

Jack R. Strosnider, Jr., Deputy Director Division of Engineering Office of Nuclear Reactor Regulation

Joram Hopenfeld Generic Safety Issues Branch Division of Engineering Technology Office of Nuclear Regulatory Research

FROM: Jocelyn A. Mitchell . 6 lv/-& Technical Assistant Office of the Executive Director for Operations

SUBJECT: DPO REGARDING REPAIR CRITERIA FOR STEAM GENERATOR TUBES - CSARP MEETING VIEWGRAPHS

The attached are viewgraphs from three of the presentations at the Cooperative Severe Accident Research Program meeting, which was held in Bethesda, MD, May 4-7, 1998. These presentations discussed calculations or experiments of deposition in steam generator tubes and may be germane to the issue of steam generator integrity. The three are:

(1) "Current Status of VEGA Project and Analytical Activities on Aerosol Behavior at JAERI," A. Hidaka, et al.

(2) "ASTEC integral code: Status of development and validation; First application to PHEBUS.FP," F. Jacq, et al.

(3) "Analysis of the two first PHEBUS.FP tests: fuel bundle degradation, Fission Product release, transport in the circuit and behaviour in the containment," S. Bourdon, et al.

If you need further information about any of these presentations or the underlying work, I suggest that you contact Charles Ader, Chief, Accident Evaluation Branch, Office of Nuclear Regulatory Research.

Attachment: As stated

ZAr' / *7

L .A

I

S.Bourdon, F.Serre, M.Kissane, DJacquemain

IPSN/DRS/SEMAR Cadarache, France

First two PHEBUS.FP experiments

Fuel bundle degradation

FP release and transport

FP behaviour in the containment

I

N

.32.

ix C-A ~5j~A

HIM.

kI ýa

li

6A .0 0 4 o)

uuhO. 1hji'i 9g ~. Is 0<111LBU3

p..W

aC

V

ISPHEBUS FPT1: Boundary conditions and ICARE2 modeling (similar for FPTO)

WOWa (kV).I (K) STEA FLOW (GIS) so.-.l , -i w ! .- 1 '

40. Pmaxa-42 kW I

117:/

10. -/

K14 SIFF

own

3 Main Phases (Calibration, Oxidation and High Temperature Phases)

b Main.Damage Events Identified during the Test I Cladding Burst "* Control Rod Failure and Relocation "* Temperature Escalation due to Zry Oxidation "* Progressive Fuel Relocation observed during

ICARE2 (VZ mod2) modeling

0 Detailed Modeling of the different Components

0 2 Radial Fluid Channels, 3 representative Fuel Rods (Irradiated and Fresh Fuel), Grids, UST and Stiffeners

' 22 Axial Meshes for Fuel (from 0 to 1. m

r"Schematic presentation of the circuits I PWR => Phebus scaling-down factor: -5000

Soo

F Temperature histories In the ICARE2 FPTO and FPT1 calculations

28=00. PA 2400.

240. I in

- - - -- PmaxF-l)I.4 20=00. Pmznx(FIT)9-5O kW 2. Pmatc14111

10=0

CS), CS) eo .400 is" i•o0 4IDO 000. 7000. •I=O. 13MX. I=O.-19000.30.60D90.I= LMI .

FHM FPM , '78MA•ES AT 0.70 m UVAT PM FPT1 t 1":1A1rS AT 0.80 m ELEVA"I%

IC FUEL, TC W nEMCI GTIU, STFE, M DSE Z=RCIA

P. During Oxidation Runaway : larger temperature peak in FT0 (-2800 K) than in FPTI (-2400 K)

- Code-to-data Discrepencies for the Late Phase due to Progressive Melt Relocation identified at 2540 K in IFPTO and 2450 K in FP`T1 (estimation bisedi on the results of the ICARE2 calculations)

Hydrogen production in the ICARE2 FPTO and FPT1 calculations

a.u. a.u.

ri sent W

I W.0tt E nflf.P

• FpO, •1• u• •0•'I0XRM• "I , MM t =t•• PW=0cN° IMJ "MT , ixUomE tiAS PRWC1I0t eidrFTick~iGNtIS P0UCl~

o Calculated H2 Production (Urbanic-Heidrick v- Calculated H2 Production (Urbanic-Heidrick

correlations) correlations)

*-18% during the Pre-Oxidation Phase (slight 9 -37% during the Pre-Oxidation Phase (slight

overprediction) overprediction)

* -4Q•% during Temperature Escalation * -38% during Temperature Escalation

_ I_

Conclusi--ns

Conclusions of the FPTO and FPT1 analyses using ICARE2 code

.- Calibration Phase * Correct prediction of the bundle temperatures. Cladding burst calculated at 1090-1100 K (EDGAR

=odel) I Oxidation Phase

"* Correct prediction of the control rod failure using temperature criterion (1730 K--melting temperature of S. Steel)

"• Temperature escalation correctly calculated using URBANIC-HEIDRICK correlations assuming intact cladding (criterion for clad dislocation : T>2700 K or T>2600 K and E=Jn<250 pmo)

"* Calculated total H2 production inside the experimental uncertainty range "• Calculated state of the bundle at the end of the oxidation phase : low fuel dissolution by molten Zry

(200-400 g in the upper part) due to high cladding oxidation and low bundle degradation

"I Melt Progression Phase:

* Large underprediction of the bundle degradation at the end of the calculations

* Correct reproduction of the experimental data using a reduction of the melting temperature of fuel (solidus -2500 K)

"i Correct calculation of the temperature responses in the lower part of the shroud

"i Calculated bundle degradation in better agreement with the post irradiation examinations (estimation of the mass of materials in the frozen molten pool: FPTO-3.2 kg and in FPT1-2 kg)

ue g ti=_

- Results of the FPTI ICARE2 calculation assuming a reduced melting temperature (solidus 2450 K)

1.

RP•AI•N)] I I "- I=•

- -- --- - --- DI Ii IT "TT - 0A

0.•- 0. 0 0,0 02 .

Material Distribution (imposed in the calculation in the K RTI SAIE TH RM

lower part of the bundle) AT -1W 9M

I

L

II FP release and transport

Outline of codes

o FP release: * ELSA version 1.1 riv.l: semi-empirical models targeting dominant phenomena,

* intact fuel, 3 FP categories: volatiles (in-grain diffusion), semi-volatiles (evaporation into

porosities), and non-volatile (fuel volatilization).

+ MFPR version 1.0 r6v.1: mechanistic (FASTGRASSNICTORIA type) models,

"* intact fuel, "* only volatile FPs,

"• initial state from irradiation, grain growth, atomic and bubble (intra & intergranular)

migration,

"* Cs and I chemistry, fuel oxidation by steam,

"* volatile FP release following liquefaction.

O FP transport: • SOPHAEROS Vl.1 (coupled with CATHARE2

rdv. :mechanistic vapour and aerosol modelling,

* vapour-phase chemistry, chemisorption,

* vapour condensation, * aerosol deposition and agglomeration.

VI.3) and VI.3

FP RELEASE

> ELSA analyses of FPTO

iodine release: effect of diffusion distance, L (SN=50)

Released fraction

I-0-L- 10 VinhfoAl, (42ff*oW*l SLe ain md(42mvY~j

!-.*-L" Sr• •4

000 MW o o0 0 Time (a)

-10000s

Isource: I, Cs, Te, Ba, La, Ru, Mo, Ag (72g.), In (13g.), Cd (18g.), U02 (180g.).

- - *r�a ot

SOPHAEROS analysis of FPTO: SG deposition

temperatures: 700 -> 150*C, unexpected phenomenon: mechanical resuspension during FPTO inerting (Re=1 900, laminar !) SOPHAEROS results:

*over-estimation of the calculated retention / experimental result: "* factor 1.4 for iodine (vapour at 7006C), "* factor 2.5 for caesium and for aerosols.

U" similar work on FPTJ still in progress. *sensitivity studies for FPT0:aerosol thermal conductivity, aerosol size,

"* no improvement in agreement, "* mechanical resuspension throughout test ?

SOPHAEROS analysis of FPTI: vapour species

upper CsOH, Cs2MoO4 Agl, Csl Te2 (10"7 gfcm3) ; plenum (10" g/cm3); (10- glcm3); some Te, ToO,

some Csl; some I, HI, AgTe; I2Te, AgTe; trace Cs, CsO trace Inl, Cdl, trace Ag2Te, Te2

HIO, CdI2 point C Cs2MoO4 I2Te (10- glcm3); Te2, I2Te

(10".1g/cm 3) ; some HI, AgI, CsI; (10"' g/cm3); trace CsI, CsOH trace Cdl, AgTe trace Te, H2Te,

AgTe, Te0. CdTe point G Cs2Te I2Te (10e gcm3) ; Te2 (10-7 gcm3);

(101,2 g/crn3); trace H2Te some I2Te ; trace Cs2MoO4 _trace Cs2Te, H2Te

p

CS i "re

Conclusions

volatile FP release:

+ ELSA interpretation: suitable diffusion length must be used for low bum-up fuel

+ MFPR interpretation (consistent with ELSA): shows slower increase of intragranular bubbles, and thus a later opening of porosities in FPTO compared

to FPTL. w- correct phenomenological sequence, but wrong timing.

semi-volatile FP release:

4 ELSA evaluation: too high for FM0 and FPTl, but model validated on

analytical tests. w- paradox unexplained at present.

FP transport: + SOPHAEROS can explain broadly the experimental results, producing a

consistent image with candidate FP species,

* gas-phase chemistry is crucial. w- impact of transitional metals (and silicon) on Cs and I behaviour is marked.

bM FPTo Thermalhydraulics behavior

the behavior of the containment vessel (REPF 502) is controlled by the

imposed wall temperatures and by the steam and H2 mass flow rates.

satisfactory simulation with the OD JERICHO code (part of ESCADRE),

particularly the condensation flow rate:

+ when using the Reynolds analogy (negligible heat and mass transfer coupling)

and the Chilton-Colbum or Collier models,

* but under-prediction of the steam pressure with the Uchida correlation.

complementary calculations with the mechanistic 3D code TRIO.VF (CEA)

*confirms the JERICHO hypothesis of a well-mixed atmosphere,

* shows a mixed convection flow pattern: "* natural convection in the lower part of the vessel, and far from condensers,

"• jet influence in the upper part of the vessel, and face to the condensers.

w, current applications of the multi-compartfent code RALOC (part of the

ASTEC code) on FPTO and FPT1.

I __

FPTO and FPTI: Iodine behaviour

Main results : FPT-1 test confirmed the overall behaviour observed in FPT-O:

* presence of gaseous iodine in the containment during early degradation phase explained by iodine injected in gaseous form from the circuit.

4 iodine rapidly deposited in the sump as insoluble Ag&; consequently, no observed revolatilisation of iodine due to radiolysis, even though the sump pH was acid.

* gaseous iodine on the long term produced by release from containment surfaces (potential mechanism : organic iodides production from painted condenser surfaces); obtention of equilibrium concentrations.

Implications for modelling of iodine chemistry in the containment: * inadequate current modelling in IODE mod 4.1 (iodine concentrations and

partition determined from formation of volatile iodine in the sump, transfer to the containment atmosphere, loss by deposition on surfaces).

Snecessary developments (besides developing a better understanding of RCS chemistry) will be integrated in future versions of the code IODE:

"* modelling of kinetics of organic iodides formation/decomposition, "* modelling of Ag/I interactions describing Ag chemistry in the containment (oxidation

processes), AgI formation and stability.

�-'t e�½or teco

FPTO and FPT1: Iodine behaviour

o the whole analysis of the first two PHEBUS.FP tests (FPT , EPTI) already

led to improvements of models in some of the codes or to reorientation of

R&D programs on open problems, for instance: + fuel liquefaction temperature,

+ importance of thermochemistry in primary circuit: existence of gaseous Iodine

at the entrance of the containment, low volatility of Caesium at 7000C,

+ trapping of Iodine by Silver in the sump water.

o the updated codes (ICARE2, ELSA, SOPHABROS, RALOC,...) are now in

use preparing the next PHEBUS.FP experiments (FTM2 and FPT4).

I --

Current Status of VEGA Project and Analytical Activities on Aerosol

Behavior at JAERI

A. Hidaka, T. Nakamura, Y. Harada, T. Kudo and J. Sugimoto Japan Atomic Energy Research Institute

Presented at.Spring 1998 CSARP Meeting

May 4-7, 1998, Bethesda, U.S.A.

Current Status of VEGA Project and Analytical Activities on Aerosol Behavior at JAERI

Akhde HIDAKA, Takchiko NAKAMURA, Yuhe HARADA, Tamotsu KUDO and Jun SUGIMOTO Japan Atomic Energy Research Institute

Abstract

VEGA (Verification E=xperiments of Gas/Asol release) project has been performed at JAERI to in'estigate the release of FP (Fission Products) including non-volatile or short-life radionuclides from Japanese LWR fuel at -30001C under high pressure condition up to 1.0 MPa. Fundameatal capabilities of cxperimental facility have been confirmed. The facilty is being installed into hot cell and will be completed in June, 1998. Two preliminary experiments during FY1998 and four experiments in a year after F1V1999 we scheduled. Pre-test analysis for preparation of operational conditions will be conducted with VICTORIA code. Fabrication of ThO= tube was mostly sucessful by using centrifugal slip casting technique and will be continuously examined for the use in VEGA xperimennts after FY1999. FP release from MOX of ATR Fugen will be investigated in future.

It was recently pointed out that the integrity of steam generator (SG) tube during secondary system depressurization would be threatened by a large pressure difference between primary and seciindary systems and temperature increase by hot kg counter current flow and decay heat from deposited FPs. In order to investigate the effect of Oceay heat from deposited FP on the stcam generator tube integrity, FP be.havior in SG during a total station blackout (TIhI) sequcne of Surry nucim plant with and without secondary system dcpressurization was analyzed at first with JAERI' s ART code. The analysis showed that relatively large amount of FPs may deposit on SG U-tube Inlet surface mainly by thermophoresis. As a next step, the thcrmohydraulic and structural response analysis with SCDAPiRALAP5 wus performed and. predicted a small safety margin for SG U-tube integrity during secondary system depressurization. Taking into account uncertanties in the presct analysis, the potential for steam generator tube rupture (SGTR) after core heat up cannot be ignored during secondary system depressurization.

Contents

1. Introduction

2. Status of VEGA Project

3. Analysis of FP Behavior in SG Tube. during Secondary System Depressurization

4. Summary

1. Introduction * Large uncertainties in FP gas/aerosol release and

transport under'severe accident Conditions

* VEGA (Verification Experiments of Gas/Aerosol

Release) project at JAERI to investigate FP

release from LWR fuel at -3000 0C under high

pressure (I.OMPa) condition

* Analysis of FP behavior in SG tube in case of

secondary system depressurization tO investigate

the tube integrity during severe accidents

9

• 2. Status of VEGA Project * Objectives

- To obtain FP release data from fuel under severe accident conditions To investigate FP behavior in reactor core and coolant system

0 Special Targets - FP release from high temperature fuel (including

debris bed) - Effect of ambient pressure on FP release - Non-volatile/short-life FP release

3

VEGA Facility

CHARCOAL FILTER (IN UOUID NITROGEN)

4

Schematic of VEGA Furnace

Graphite Susceptor (Heated by Induction Coil)

Quartz

SCarbon

Carbon • Felt Powder'

Induction Coil

(ThO2 or ZrO2)

e (ThO2 or ZrO2)

Carbon

in I

ing

P Yrometer 5

Heat-up Test with VEGA Furnace(Reducing Condition)

3000

2000

1000

C0 50 100

Time (min)' . r

150

20min 30min , •

... ArGas : NI/min Susceptor Graphite Inner tube Graphite Pressure 0.93MPa

I I 2

1500

1000 "E

0

0 500" C.

V-

00

CD

C_

u_

2

Experimental Conditions * Test sample ; 6cm long, 1Og

- BWR Tsuruga Unit I ; 26GWd/tU - PWR Mihama Unit 2 ; 39GWd/tU

Ohi Unit 1, 2 ; ~50GWd/tU - TMI-2 debris sample - ATR Fugen ; MOX fuel

* Re-irradiation of test fuel using NSRR to accumulate short-life radionuclides

* Max. temperature ; 30000C. (Isothermal induction heating in ZrO or ThO2 tube furnace)

7

Measurement a On-line gamma measurement

- Filters or Impactor : Cs-1 37, 1-131, Ba-140 (La-1 40)

- Charcoal traps : 1-131 - Cooled charcoal : Kr-85, Xe-133

* 3 Thermal Gradient Tubes: (750-2000C) * On-line oxygen/hydrogen measurement * Off-line gamma spectrometry * SEM/EPMA, SIMA 0 Metallography * ICP-MS (for solution).

* Requirement for Furnace Material- Stable under high temperature > 30000C and oxidized conditions .... M.P. > 30000C Stability under oxidized condition Remark

ThO2 0 (3370*C) 0 Nuclear material

W 0 (3382-C) x Expensive

ZrO2 x (2677-C) . OUseuin Exp.'(< 2400'C)

E Method for Fabrication ; centrifugal slip casting technique- �Iin nrenaration by chanainq water, water dispersant and binder

Slip No. 1 2 3 4 5 6

ThO, powder (g) 1400 1400 1400 1400 1400 1400

Water(%) 35 30 32.5 35 35 35

Water dispersant (%) 0.3 0.3 0.3 0.35 0.3 0.3

Binder (%) 0.54 0.54 0.54 0.54 0.34 0.73

Viscosity (mPa.s) 60 2939 507 .69 50 542

Sintering at 17000C 0 x (Crack) x x x x

9

Preliminary VEGA Test Schedule

FY 1998 1999 2000 2001 2002 2003 2004 2005

Preliminary Test 3000°C He carrier Effect of ATRMOX ATRMOX Synthetic Target test initiation high gas bum up test start 30000C tests

pressure

2400-, 2800-C 2800-C 3000CI 3000*C 24006C 3000dC not

0.1MPa 0.1MPa 0.1MPa 0.IMPa 1.OMPa 0.1MPa 0.1MPa decided H20/P H20/P H20iB H20/B(NS) H20/B(NS) H20/MOX H20/MOX

24001C 2400*C 3000°C 3000CC 30009C 24006C 30000C

1.OMPa 0.1MPa 1.OMPa 0.1MPa 0.1MPa 1.OMPa 1.OMPa not

Expern- 2 H20/P H20/B H20/P(NS) He/P H20/P H20/MOX H20/MOX decided

mental Low burn up , I

Condition -. 3000*C 500/1200rC 3000C 3000CC 28001C 500,1200VC

0.1MPa 0.1MPa 1.OMPa 0.1MPa 0.1MPa 0.1MPa not

H2OIP(NS) AirJ`P He/P H20/P He/MOX Air/MOX decided High burn up

2800CC 500,'1200CC no 3000CC 3000'C 500/1200*C Make-up not 50M20 1 M

4 0.1MPa 1.OMPa 1.OMPa /.0MPXa 0.1MPa HeITMI He/TMI Air/P Exp. HefMOX Air/MOX decided

Note) P:PWRfuel B:BWR fuel NS:NSRR irradiation TMI:TMIdebris

10

- . Analysis of FP Behavior in SG Tube during Secondary System Depressurization

? .1 Introduction "* Resolution of DCH issues for PWRs

- Failure of hot-leg or surge line prior to RPV meltthrough "* Secondary system depressurization as one of AM

procedures for high pressure sequence - Primary system depressurization followed by HPI

activation or ACC injection V Questionable SG U-tube integrity during'secondary

system depressurization- Pressure difference and temperature increase by CCNC and

FP decay heat

11

* Hot-leg or surge line failure prior to SGTR is preferable from a view point of AM.

* Recent SCDAP/RELAP5 analyses by USNRC showed SG U-tube integrity during secondary system depressurization.

- No FP decay heat in the analysis

* Objectives of present study -- To evaluate FP deposition and decay heat at SG tube

with JAERI's ART - To investigate effect of decay heat on SG tube

integrity during secondary system depressurization with SCDAP/RELAP5

12

3.2 Analytical Method * Reference plant - Surry plant (Westinghouse 3-loop PWR, 2441 MWt)

* Analytical sequence - TM LB' (with/without secondary system depressurization)

- All MSRVs opening at 300s after accident initiation

(1) FP deposition Analysis * Computer code -- ART/Mod2 developed by JAERI

* Boundary conditions for ART calculation -- Csl/CsOH concentrations in superheated steam based on

similar MELCOR calculation

13

* Csl gas concentration =0.006kg/rn * CsOH gas concentration = 0.040kg/m3

- Gas/wall temperatures at SG U-tube equal to SCDAP/ RELAP5 calculation without decay heat

* Decay heat calculated by ART was given to surge

line, hot leg and SG U-tube heat structures in

SCDAP/RELAP5 calculation.

* Assumptions - FP deposition occurs when fuel temperature reaches

1500K. - Constant decay heat used in the calculation was decided

based on FP deposition calculation for 2000s

IA

• (2)Thtrmohydraulic and Structural Response Analysis

lo Computer code - SCDAP/RELAP5/Mod3.1 (Release D)

* Input data prepared originally by INEL - Use of hot-leg CCNC model after the onset of core heat up - CCNC model prepared based on Westinghouse 1/7 scale

model experiment

0 Creep rupture calculation for hot leg, surge line, SG U-tube and RPV bottom head by Larson-Miller theory.

0 Break area = 0.19034ft 2 = 0.01769m2

15

3.3 Analytical Results Temperature Distribution in SG U-Tube

1000

950 95 / Steam 90Wall with MSRV Bleed; 12300s S900 Wal

1_

S~Steam 850 without MSRV Bleed ; 13800s

CL800 E strew

750

700 ---0.0 1.0 2.0 .3.0 4.0 5.0 6.0 7.0

Elevation (in)

Elevation

(m)

Deposited Mass. at SG U--Tubat (with MSRV Bleed)

100 ) 10°1I

CsOH

Cl) 10-2 %

10~-3

0.0 2.0 4.0 6.0

Elevation(m)

17

Averaged FP Deposition Velocity (with MSRV Bleed)

10 -4~ . . . .. , .. . .1 ... , .. 1,.... ,. .

10,7

Thermophoresis

Turbulent > 10-6 Brownian Diff usion > 1- .0

107,

0.0 2.0 4.0 6.0

Elevation(m)

18

* D~ecay Power at SG U-Tube Inlet Ix1081

500 1,000 1,500

Time (s)

19

U-Tube and Surge Line Temperatures - (with MSRV Bleed)

iSG 3000 W/m2 " U-Tube 4000 W/m2

Decay Heat - 3000 W/n

X.: Creep Failure

3000 W/m 2

~Surge 4000 Wf 2

--]\ .4000 W/m2"

12000

Time (s)

20

3.0

2.0

1.0

E

I_

0 0C

0.00 2,000

1000

800

.)

0. E I-

600

10000 11000 13000 14000

...............

4. Summary (1/2) (1) VEGA Project * Fundamental capabilities of experimental facility have

been confirmed.

*The facility is being installed into hot cell and will be completed in June, 1998.

*Two preliminary experiments during FY1998 and four experiments In a year after FY1999.

* Pre-test analyses will be conducted with VICTORIA code.

* Fabrication of ThO2 tube will be continuously examined.

* FP release from MOX of ATR Fugen will be investigated in future.

21

4. Summary (2/2) (2) FP Behavior Analysis in SG U-Tube

"* FP behavior in SG U-tube during TMLB' with and without secondary system depressurization was analyzed with ART.

"* Present analysis showed that relatively large amount of FPs may deposit on SG U-tube inlet surface mainly by thermophoresis.

"* Thermohydraulic and structural response analysis with SCDAP/RELAP5 predicted small safety margin for SG U-tube

Integrity during secondary system depressurization.

"* Considering associated uncertainties, potential for SGTR after

core heat up cannot be ignored during secondary system depressurization.

-�

GRS

FJacq, W.Plumecocq, J.P.Van Dorsselaere*

C.Bassi** HJ.A~lelein, W.Klein-Hessling, J.Bestele***

IPSN/DRS/SEMAR Cadarache, France

IPSN/DPEA/SEAC Fontenay-aux-Roses, France

ORS K61n and Garching, Germany

Contents

ED ASTEC context and objectives

D Status of ASTEC VO version

0 First ASTEC applications to PHEBUS.FP (FPTO, FPT1)

SPerspectives for the ASTEC V I version

ASTEC integral code Status of development, and validation

First appication to PHEBUS.FP.

*

**

I GRSIJIS

lTh ASI' egepil code, is &deWWoe in dms clahboration by MPS and C~s for fte evaljugon of soro- -m during LWR m aeddnm. Aflter te 17 CSARP paper

Wmeating the ASTEC project. thi pper fo• n e i panft u F On vaidtio and

Me 1 rs•io VO. was imilly deliv be•inving of 19M to VWSN Wd WS *ta , w a fira set aof t-aa and wiJ a = 5's docm -on Wi-line- A .c'Oaodado" ptae iS

uently peMfmzd with a comarison wi the IPM n~refer code, EWCA=E. on 1I

rec-cum w vlda•on of die Version VO is oinaly perormed cn aeparateffect* ex=peiffn on

u Ge=ia "d ftorg pogsrams (lUBA. VM DC.AML, WFA. VANAMI

MaR. KAXEYH,.4 Afirutstagectvalidaton is forueen a"-9 an about 25 tests wtiidi coer d.e main ftinomana. and coul allow firt reame VpltO=W= for "dienIuch PSA2 studime Som firsttesuh of tie validation am pasented b•. An irnportat action is ie on 00 tegral P MEBUS.W erimnu• x-I die FPM0 and FP71 ones. T•e M0 pp•Icon is up to ow roomed on ihe b. dgadation pha= with the VLJLCMIN module. VJte4 s p&= mA.1;atn aidr to ICA=m and WAAN ONs. a global ap~enuht is cbtained an die seznt= of events. partiwluly on fueldad rupnum (using die Oaprouinm correlation) and on 7Zy addation. (hydogen produd main and kinetic). But dieances nmlnan the dinology (dWays an control ptd inu and on ful collaps).

Tbe Pr applicaion h am up to now with puall Wno e Mlications to die priwmy circuit on on hand (soo pcelirnay result ame pesented here) and to die containmtel on the od•rnmd:

- as for ie. crcui. the coupling of dti followg modules. VULCAIN (unde degrdaon )-W.SA (FP tekes),SOPHAEOS (FP and osol transport), gives

sfacory rnidts. The global agreUt with the experintal UJlts is good, and the

Calclations of e bundle dega dain am consient betveen FFr0 and Wrl-. . in the CPA module for the couuinment, themhydrul•cs (based on RALOC), aerosol behavimr (based on FR OC) and iodine behaviour (based on IODE) am coupled.

TMe complete coupling of ill the modules will be performed in the next months. Finally, the perpectives for the next version VI (scheduled for end 1999-beginning 2000) are sunid up:

- RCS 2-phase simplified thednihydraulicks during both tf front end and the core

degradation phases * new core degradation module, based on ICARE2 stacture and simplified models, - possible improvement or repl•ment of the WECHSL module for the MCCI. Supding of soma cornwsitve modules (ISA SOPHAEROS and IODE).

ASTEC Context and objectives GRSi Summary of the CSARP 1997 presentation

D IPSN/GRS cooperation for an integral code for LWR source term severe

accident calculation.

D Main requirements: PSA2, accident management.

o Specifications: * the best modeling from IPSN/GRS integral approach,

* ((reasonable)> calculation time (fast-running code),

* accounting for safety systems and their availability.

0 Coupling with the IPSN SUNSET tool for statistical analysis.

o Version VO based on the best models from:

4 ESCADRE mod 1.1 IPSN integral code for the RCS and for Iodine behaviour in the containment,

* RALOC/FIPLOC (CPA) GRS codes for aerosols and thermalhydraulics in the containment.

O SIGAL data-base: stand-alone running mode or coupled running mode.

f =.=

I -

rn MOXT-i-f'-1100 O'kniff I A MP.n/v.-nr-

S•I COUPLED mode : allows explicit feedbacks ) • STAND-ALONE mode : allows module

.validationJaks

__ Status of ASTEC VO version G

: Internal release of the VO.1 version to IPSN and GRS users in January 1998, with: * 13 test-cases on <(separate-effect) experiments, * 5 reactor test-cases on PWR 1300 MWe (4 tests with one compartment and 1

test with 45 compartments), * with user's documentation on-line: performed to 95%.

S Current <consolidation>) of the version VO. 1: * comparison with ESCADRE mod 1.1 on the 15 single-compartment reactor

cases used for ESCADRE delivery,

* extension to other reactor multi-compartment tests (TMLB, S2CD, A, AB). * completion of the documentation.

w- continuous corrective evolution, with a mid-98 objective of a version able to be used for French PSA2.

SValidation:

* minimum validation document for mid-98: 25 separate-effect tests,

* complementary validation in late 1998 and in 1999 (PHEBUS.FP, TMI-2, ... ).

+ current application to the PHEBUS.FP integral tests FPTO and FPT1.

. ASTEC VO - Basic Validation Matrix.1

hump evapurau decay heating rm1 I I

I I I

N4 HI V K N SP A C

D D UM A A U It C H H a

A V a a L A V A 5

111.2 B12S OA M4 a C U A S k U Mc17.1 S.

InlA I S SM4R 81 . 29 1. 2

HCombustonlPass.Autocat RecOnlb -

Teu. distnbutiof O' D 05 OD oj5 0

(stratific. orning light gsdistribution 0VI -- - - --0,

steam distributionl 5 --- - - - - - V

Convection 0en -Z 65 -V

E!=mod~tii 0 -Ov 0- 5 O. ------

Sensible beat transfer 6 95 65 7- r. - - - - - - - - - - - - -

spa ySystem 0 -. -- I---a ---- -)

-4 - N--

I"tolamile FP 0 0 01

N-ovolatile FP

ARIomc tation..oW__lI.II_ t--' io n 31 1 I

Diffusiopbonris. I I I Condensationo ersl

• ononhygros'---'. 0ý1

aerosolsI Mut-on.effects

Trbuetdiolusc.Itafons

e reactosl recions iun 0

Rdoyic reaction atmosphere (Oone) unorganic iodides . VV

orai iodides 7 -V

)sum tmosph.vltl species mass t-a-sfer Deposition on solid

surflaces )I VI I IIIv

effect of steam condensation an walls

water dropletsatmosphere mass transfer

p~articulate iodine behav.

I

Multi comparmwns

V V

oxiationI A

fuldssolu tion"'" m ,neram mels u

nflen pool V

correactionS giný JS1mp

I st failu---"' •riyti ablation

a o hr el a nd

I

I

IvSI I II

I

I•.A.8 '

ASTEC VO - Basic Validation Matrix 15.4.98

A B A A A A S S S S K T T D~ A T. C E N N N N N N N N A U U E E R A PH-MUS E T L L L. L L L L L E B V R A L

A R A A A O N C P1 L215n U2 UIA MI 17 tET4 IET6 M-TSB IMl I P D S 0

1.8 UB IETIO 772A TN E.Aj 08 V T

A is P TR2 - a - .

I I I 11 _ 04 1 1 .• ,?

Prot. corium O,D 0,D V H, burning OD 0 0 M V Scale effect 0 0 V

enainment (driving O.D O,D 0 0 0 0 V

Cavity w-ter mitiplon -. Insulat.disrupt.mitig. M iI-

Aerosols settling' M _ V *minar diffusion M"_"_ V

Turbulent diffusion M V Eddy irnpaction. - - M Bend impaction. - M V

Thermophoresis. - M_ V Diffusiophoresis D V Vapor FP xondievap. 0 M - D V on walls Vapor FP condievap. M V on aerosols Soybtion O M . D V

Zirconium content OD O,13 R H C up. surface 0,D1 2 layers (oxilmetal) O,D I layer O,D

m et. disper. in oxid.) - -i

Siliceous concrete O,D O,13 limest. sand concrete O .D O,D

0 : means validation performed with an old (stand alone) version eD:means valid. calculation performed with ASTEC VO as DeHUveng Cane which were performed until the delivering of ASTEC VO;

* M:Mimum VPSA. d ntformedto wfrstrctorapplicationsforinstanceforPSA.Milestone mid 1998 * V : means complementary validation calculations intended for ASTEC VO, but not necessarily until mid 1998 • *: global validation calculation for PHEBUS FPTO, FPTI, perhaps TM12 which serves simultaneously as demonstration calculations

_ _ _ 1 -- 1

First results of validation (ELSA module)

VERCORS4 experiment (IPSN program): influence of a reducing

atmosphere (H2) on aerosol and FP release; fuel temperature up to 23000C,

* good agreement on the volatile FP release (kinetics and total release).

HEVA-6 experiment (IPSN program): similar test conditions (except fuel

temperature up to 2075°C) and validation conclusions.

" . . . . . ... . * . . . .:

:.: . .:

•. -,........ . ........ .. . ....... ... o ... ..... 0 ..... ........ ... ... .. .. .. . . .. . ... .

...... ..

. ............... ...... ............. ..... .... ..... ......

.. .. . . . . .........

W to o. M 3.0 0 4.. 10. .

VERCORS4 computed with ELSA ASTEC Heva6 computed with ELSA ASTEC

f ScOeof Me F.P. Xe Kr I Sr C&IRb Cu VersionO.I Rek.ad taction of votatfic F.P. Xe Kr I Ur C& tb Ca VersionO.i

First results of validation (SOPHAEROS module)

TUBA-D: IPSN experiments for diffusiophoretic retention in a SG pipe:

* injection of a steam-helium mixture with CsI aerosols,

* results of the application to the TUBA-D TD07 experiment (see graphs below,

where only the average experimental deposition value is available):

- good global agreement on condensation (72.3% /74.6%) and on retention (63% /58%)

* contribution: diffusiophoresis 94%, thermophoresis 6%.

pANL DCH tests in Zion geometry at 1/40 scale, with prototypical corium, good agreement on pressure: vessel blowdown and increase in cavity, good agreement on cumulated steam mass, but under-estimation of H2 production (short entrainment duration and under-estimation of oxidation).

Oe -4?

... .......... ...... . ...

'" ....."..:.... .:" ""i.....":.......• ..... .

0 81 *A 0.6 SA.4 , 4 .A

Direct Containment Heating by RUPLIICUV ASTECI A3JL.WZý Vcrwjg 0.2

. ' ... ... ... .. ... . ... ... ... ... ..... as

D irec t t o ine enm t H o stin g b y tu P K C v V S T -C A~e~flVen"ce 0. 1

First results of validation (CPA)

VANAM: thermalhydraulic and aerosol program,

* M3 test (ISP 37): injection of steam, air and aerosol into a multicompartment containment.

CPA results: * good agreement on temperatures, except for the lower

room R6 (need for splitting of R6).

* good agreement on humidity with the non-equilibrium model, but problems in the annulus zones.

* good agreement on the dry and wet aerosol depletion.

tee ..... .. .. ........ ..... .......... ...... !

• 4 .. .. .. . . . . . ........ . . .. .. . . ..

do .. ...... .. . . .. . . . . . .. . ...

30 .. .

*so ~ q

ASTEC VO, V.C 9*UI-J2 EgaCOP-

LS=w VO

130 "W-'

.... ..... ". .......

ASTEC VO. SEC9

.. .. .. . .. . . .. ..

1 . . ...... 4 .. ......

.. . .. . . 6.. . . ..

ASTEC VO, sc9 arc V"fl-iU EMOC~Awlcul~

First results of validation (RUPUICUV module)

GRS

=I

rr

Crono~dogy (s) fuel rod clad contol rod 1Zz02 - U02 nolten pool

failure failur relocto rocton fo~nmtion

calculation 6940-7180 11920 14940 -152101 16150

Epezint 6960 10788 first naterial moveen=ts 15180 from 14000

_ _ ;st S-T aflicaflfiIn iitO, ýBU

FPTO core nodalization (VULCAIN) "dense ZrO2 (ZIRD) Zr02 shroud (ZROB)

zircaloy zircaloy

U02 U02 porous Zr02 (ZIRP)- Inconel (N) AIC

/ .....

[iiiiiiiiii

..... ing.2.....

ring 2 QR2)

....... 1,0m

........ 0,9m

....... 0,8 m

....... 0,7 m

...... 0,6 m

................................0,5m

...... 0,4m

...... 0,3m

........ 0,2 m

....... 0 ,1 m

SI S2 S3

11. ,.... ..... °..* .

10

9 ... •. .....H

8

7

6

5

4

3

2

I ring 1 (IR1)

RS

DI 0•

..........

..........

..........

FMTO application

Focused up to now on the bundle degradation phase (VULCAIN code).

Modelization (similar to ICARE2 and MAAP4 ones):

* 2 x 11 meshing (control rod only in the 1st ring),

* characteristics of the surrounding structures issued from ICARE2 calculatons.

Satisfactory global agreement on the sequence of events, and particularly:

* on fuel clad rupture (with Chapmann correlation),

* on Zry oxidation (H2 produced mass and kinetics),

But discrepancies on: - chronology: delays on control rod rupture and on fuel rod collapse, and thus on

molten pool formation.

GmRS

E

2.

3000

2500

2500

2400

2200

2000

1500

1600

1400

1200

1000

goo

600

400

200

0

ASTEC VO - VULCAIN 7.1 code - PHESUS FPTO test 9undl* tomPeratures

lim. (S)

__ -ffpl___W _

ASTEC VO - VULCAIN 7.1 code - PHEBU S FPTO test Hydrogen maSs productd

.E14

11000 12000 *13000 14006 i-,nnn 1rw

t~nw (S)

':1 a o

"F FPT1 Hydrogen and FP release

slight over-estimation of the calculated H2 produced mass: discrepancy 7%

(VULCAIN code),

correct calculation of the total volatile FP release (ELSA-VULCAIN codes).

FPT1 transport and deposition

good global agreement on the calculated SG fluid temperatures (VULCAIN

- SOPHAEROS codes). /

two calculated zones of significant FP deposition by thermophoresis: bundle

exit and SG, " but the deposition profile is not yet satisfactory (interpretation to be

improved...).

I -

FPT1 application ASTEC VO.I parallel applications to:

* the primary circuit (VULCAIN-ELSA-SOPHAEROS), * the containment (thennalhydraulics and iodine parts of CPA). 0' coupling of the two above applications in the next future (June 98) to simulate

the whole experiment. Same bundle modelization than FPTO (except 22 axial meshes for the bundle), with 18 volumes for the circuit. First main conclusions on bundle degradation with VULCAIN: * good H2 production mass evaluation; peak slightly in advance, * good global agreement on bundle temperatures, but in the calculation:

"* oxidation peak slightly in advance, "* delay of fuel rod failure with the standard EDGAR model, "* molten pool formation delayed (because of need to reach high melting temperatures).

Qirndogy(s) fuIrodclad ccrxvlrod first 1U22,Mt MDItenpool faiufail= iur relocation recaficn fcm'ticn

Calalation 8240 9900 16230 16490 16950 Bpeinw 5800 9690 maial mNens bewen

I5900 1 19 16800

b t

FPT1 bundle temperatures M

PtMMS FPT1. ASTEC VO.1 &r4d t=%W tugg an kl 6 (M0 - 3W0 mmi

Axes of reflexion

Main foreseen improvements: * RCS 2-phase flow thermanahydraulics during the front end and during the

degradation (specifications mid-98): * simplified models derived from French CATHARE code,

. further validation against the reference codes CATHARE and ATHLET.

*new core degradation part:

* based on ICARE2 structure, * models derived either from simplified ICARE2 ones or from VULCAIN.

Reflexion on the necessity of general improvement or replacement of

WECHSL for MCCI.

Improvement of models (update of some constitutive modules):

"* FP release for advanced degradation (ELSA 1.2),

"* gas-phase chemistry, aerosol mechanical resuspension and vapour homogeneous

nucleation (SOPHAEROS 2.0), and later pool scrubbing,

"* Ag/I reactions in the water sump (lODE 4.2).

Improvement of the informatic structure: ODESSA (SIGAL interface

module in F90).

r Schedule: end of 1999- beginning of 2000.