EUROTRANS – DM1

ENEA Activities on EFIT Safety Analysis

ENEA – FIS/NUCBologna - Italy

WP5.1 Progress Meeting Tractebel / Brussels, March 17, 2006

G. Bandini, P. Meloni, M. Polidori

OUTLINE

Planned Activities on EFIT Safety Analysis

Transient Analysis with RELAP5/PARCS

Use of SIMMER-III in MEGAPIE Safety Study and DM4 - DEMETRA

SGTR Analysis with SIMMER-III

Preliminary SIMMER-III Results

ENEA Activities on EFIT Safety Analysis

Analysis of DBC and DEC transients with RELAP5/ PARCS coupled code

Analysis of the SGTR and water-lead interaction with SIMMER-III code

Transient Analysis with RELAP5/PARCS Planned Approach

Capability to treat global system behavior coupled with dynamic core response in transient conditions

Investigation of whole spectrum of accidental DBC scenarios and DEC conditions (no severe accidents)

Main differences respect to PDS-XADS to address code upgrading and activity planning:

Lead instead of LBE as coolant

Large positive reactivity potentials without prompt Doppler

Preliminary investigation of safety issues to support core design

Transient Analysis with RELAP5/PARCS Completed and in Progress Activity

Inplementation of Lead thermodynamics and physics properties in the last RELAP version MOD3.3 (capable to be coupled with most recent PARCS versions)

Modification of v2.4 PARCS version to treat external source (hexagonal geometry, multi-group energy description)

First coupled calculations and modelling of EFIT core (preliminary design) in progress

Use of SIMMER-III in MEGAPIE Safety Study

Calculations of LBE-Water Interaction Accident for MEGAPIE

Comparison with FZK calculation with MATTINA code

SIMMER-III MATTINA

Validation of SIMMER-IIIon JAERI Experiments

LBE-Water Interaction Test

SIMMER-III and Test resultcomparison(vapor volume)

Use of SIMMER-III in DM4-DEMETRA

Lead-Water interaction experiments will be performed in the Facilities (LIFUS and/or CIRCE) of ENEA/Brasimone site

SIMMER-III code will be used in pre- and post-test analysis of these experiments

Qualification of SIMMER-III models in connection with these experiments is proposed by ENEA in close cooperation with the University of Pise

Based on the results of this work and eventual code model limits some model development work could be envisaged and proposed

ENEA asks for the agreement by the SIMMER-III development team (JNC, FZK and CEA) to perform this task in close cooperation with the University of Pise (under responsibility of ENEA)

Analysis SGTR Accident in EFITPreliminary SIMMER-III Calculations

Use of a simplified 2-D cylindrical geometry

Boundary conditions according to EFIT ANSALDO design

Stagnant lead inside the vessel

Lead liquid fuel, Water coolant in SIMMER-III lead-water interaction simulation

1 to 5 steam generator tube rupture

EFIT DesignSIMMER-III ModellingSimplified R-Z Geometry (29 x 41)

R

Z

SGTR Accident in EFITSimplified Assumptions in SIMMER-III Calculations

Reactor Vessel

Lead mass = 1850 tons (LBE properties with Tmelting = 328 °C)

Lead temperature = 400 °C

Cover gas volume = 41 m3 (T = 400 °C, P = 1 Bar)

Steam Generator

Tube inside diameter = 14.2 mm

Liquid mass = 31.1 kg; steam mass = 25.3 kg

Volume = 0.32 m3; void fraction = 84.7%

Pressure = 140 Bar; Temperature = 335 °C

Tube Rupture (1 and 5 SG tubes)

Downwards flow at the heat hexchanger bottom

Mass flowrate (1 tube) = 1.2 – 1.6 kg/s (steam and liquid mixture)

SG Break Mass Flowrate

Break Mass Flowrate (5 Tubes)

0

1

2

3

4

5

6

7

8

0 5 10 15 20Time (s)

Mas

s F

low

rate

(kg

/s)

liquid

steam

total

Break Mass Flowrate (1 Tube)

0.0

0.3

0.6

0.9

1.2

1.5

1.8

2.1

2.4

0 5 10 15 20 25 30Time (s)

Mas

s F

low

rate

(kg

/s)

liquid

steam

1 Tube

MaterialFractions

1 Tube RuptureTime = 0 – 30 s

0.1 s 1 s

3 s 10 s 30 s

MaterialFractions

5 Tubes RuptureTime = 0 – 30 s

0.1 s 1 s

3 s 10 s 30 s

System Pressure

1 Tube Rupture

t = 30 s

System Pressure

5 Tubes Rupture

t = 30 s

1 to 5 SGTube Rupture Comparison

Break Mass Flowrate

0

1

2

3

4

5

6

7

8

0 5 10 15 20 25 30Time (s)

Ma

ss

Flo

wra

te (

kg

/s) 1 Tube

5 Tubes

Vessel Cover Gas Pressure

0

100000

200000

300000

400000

500000

600000

0 5 10 15 20 25 30Time (s)

Pre

ss

ure

(P

a)

1 Tube

5 Tubes

SG Secondary Side Pressure

0.0E+00

2.0E+06

4.0E+06

6.0E+06

8.0E+06

1.0E+07

1.2E+07

1.4E+07

1.6E+07

0 5 10 15 20 25 30Time (s)

Pre

ss

ure

(P

a)

1 Tube

5 Tubes

Main Conclusions from SGTR Analysis

More suitable geometry must be chosen to model the SGTR in EFIT reactor with the SIMMER code (2-D or 3-D ?)

Boundary conditions are still uncertain

Preliminary calculations show that steam explosion effects are not of concern in the SIMMER-III evaluation

Fast vapour expansion outside the break causes a significant movement of lead mass that impacts onto the vessel upper structures

An almost linear increase of the cover gas pressure is computed by SIMMER-III in the time frame of tens of seconds