Transcript Diapositiva 1

CIRTEN
Consorzio Interuniversitario
per la Ricerca Tecnologica Nucleare
UNIVERSITA’ DI PISA
Dipartimento di Ingegneria Meccanica, Nucleare e della Produzione
Thermal hydraulic analysis
of ALFRED by RELAP5 code
& by SIMMER code
G. Barone, N. Forgione, A. Pesetti, R. Lo Frano
LEADER Technical Meeting, Karlsruhe 2012
Content
•
•
ALFRED reactor
TD-5 Loss of one primary pump: RELAP5 preliminary
nodalization
 Steady state
•
•
Needed improvements
TRB-1 Steam system piping break at SG outlet: SIMMER III
preliminary model
 Preliminary obtained results
•
Needed improvements
LEADER Technical Meeting, Karlsruhe 2012
ALFRED reactor
LEADER Technical Meeting, Karlsruhe 2012
TD5-Relap5 preliminary nodalization
8 STEAM
GENERATORS
LEADER Technical Meeting, Karlsruhe 2012
TD5-Relap5 preliminary nodalization
ALFRED 300 MWth core fuel assemblies (FA) are modeled by PIPE 876. The associated heat structure has a vertical
length of 0.6 m (FA active height) and power is assumed being generated uniformly; heat transfer is simulated by
vertical bundle convective option. Lead mass= 3.58E6 kg
RELAP geometrical parameters are
fixed according to ALFRED core:
- 171 FA, 108 Dummy elements,
-127 pins/FA, P/D=1.32, D=10.5 mm
HTC is evaluated by RELAP5
according to Ushakov correlation.
2 % of the total flow rate crosses the
core through the Dummy elements.
The gap (5 mm) between adjacent FA
and Dummy, together with the core
annular zone has been modeled; the
lead is in stagnant conditions.
FAs, Dummy and gap/core-annulus
zones are connected to ALFRED core
upper plenum, in this branch the hot
FAs lead mass flow mixes with the
by-pass one from Dummy elements,
to reach (by means of TDPJUN) the
SGs.
LEADER Technical Meeting, Karlsruhe 2012
RELAP5 preliminary nodalization
ALFRED reactor includes 8 SGs: once through double wall bayonet type (T91).
Each SG unit consists of 508 tubes with feed-water MFR of 24.1 kg/s; lead shell
side MFR of 3247.5 kg/s.
Secondary side pressure is 180 bar and feed-water enters the inner tube with a
temperature of 335 °C (subcooled, Tsat (180 bar)= 357 °C).
RELAP5 bayonet tube nodalization:
- Inner tube, water flows downwards
- Annular zone, up-flow water stars to boil
The two zones are thermally insulated by a paint layer (0.05 W/(m K)) to avoid
steam condensation.
Water reaches inner tube bottom at a temperature of 340 °C (subcooled) and
enters the annular zone reaching saturated steam conditions (quality=1) at
about 3 m height (half tube active length).
Water/Steam exchange power with liquid lead that flows in counter-current on
the tube outer surface, through double wall high conductivity gap (55 x He
conductivity).
Superheated steam is obtained at 6 m SG active length with a temperature of
451.6 °C reaching the SG Steam Plenum at a temperature of 450 °C and quality
of 1.76.
Heat exchange with lead above SG active length (6 m) has been neglected.
LEADER Technical Meeting, Karlsruhe 2012
Model set up (steady state)
500
Lead
480
Water/Steam
460
440
Temperature [°C]
420
400
380
360
340
320
300
0
1
2
3
Lenght [m]
4
LEADER Technical Meeting, Karlsruhe 2012
5
6
Model set up (steady state)
2.5E+05
4.50
4.00
2.0E+05
3.50
Heat Flux
Quality
1.5E+05
2.50
2.00
1.0E+05
1.50
1.00
5.0E+04
0.50
0.00
0.0E+00
-0.50
0
1
2
3
Lenght [m]
4
LEADER Technical Meeting, Karlsruhe 2012
5
6
Equilibrium Quality [-]
Heat Flux [W/m2]
3.00
Model set up (ULOF)
1.6
1.4
1.2
Fuel
Steam Generator
1
Velocity [m/s]
Fuel (8G)
Steam Generator (8G)
0.8
0.6
0.4
0.2
0
0
500
1000
1500
2000
2500
Time [s]
LEADER Technical Meeting, Karlsruhe 2012
3000
3500
4000
Model set up (ULOF)
740
720
700
SG-In
SG-Out
Core-In
Core-Out
Cladding Core out
SG-In (8SG)
SG-Out (8SG)
Core-In (8SG)
Core-Out (8SG)
Cladding Core out (8G)
680
660
640
620
600
Temperature [°C]
580
560
540
520
500
480
460
440
420
400
380
360
340
320
300
0
500
1000
1500
2000
2500
Time [s]
LEADER Technical Meeting, Karlsruhe 2012
3000
3500
4000
Model set up (ULOF)
35000.0
30000.0
25000.0
HTC [W/(m2 K)]
Fuel (p/d=1.32)
20000.0
Steam Generator (p/d=1.42)
Fuel (p/d=1.32) (8SG)
15000.0
Steam Generator (p/d=1.42) (8SG)
10000.0
5000.0
0.0
0
500
1000
1500
2000
Time [s]
2500
LEADER Technical Meeting, Karlsruhe 2012
3000
3500
4000
RELAP5 model improvements
The ongoing improvements are:
 Modeling the reactor kinetics (reactivity feedback)
 Introduce hot FA and hot pin in the model
 Power profile along FA active length (from Monte
Carlo simulations)
 Primary pumps with appropriate characteristic curve
instead of time dependent junctions, if available.
LEADER Technical Meeting, Karlsruhe 2012
TRB-1-SIMMER III model for SGTR analysis
feed-water tank
7 pump-SG connections
1 pump-SG connection
7 pump channels
1 pump channel
7 pumps
1 pump
7 SGs
1 SG
7 core-pump connections
1 core-pump connection
Fuel assembly extended
core
lower plate
downcomer
Partial vertical section
of the ALFRED reactor
Lead
Water
Argon
Non calculation regions
LEADER Technical Meeting, Karlsruhe 2012
Axial-symmetric
SIMMER III model
TRB-1-SIMMER III model for SGTR analysis
Ø = 7.4 mm
In SIMMER III model
the flow areas and the
axial dimensions have
been conserved.
Tube
t=5 mm
Failure plane
Bayonet tube with rupture plane
TH2O = 335 °C
TLEAD = 440 °C
Lead
Water
Argon
Non calculation
regions
PH2O = 180 bar
PARGON = 1 bar
Bayonet tube, water tank and injector orifice detail
LEADER Technical Meeting, Karlsruhe 2012
SGTR analysis: preliminary model set-up
5 m/s
Vbase
Lead velocity vectors, in stationary conditions,
before the water injection (VLEAD< 2 m/s)
Pressure distribution, in stationary conditions,
before the water injection and computational grid
LEADER Technical Meeting, Karlsruhe 2012
SGTR analysis: preliminary results
The steam, that arises from the LWI, seemed to propagate in the bottom part of core region. The
analysis is at the beginning, about 3.5s of the foreseen transient (that is assumed to begin after the
system has reached a steady state condition).
LEADER Technical Meeting, Karlsruhe 2012
SGTR analysis: preliminary results
A detail of the previous figure showing the propagation of steam in the whole
considered system : it is a preliminary results of TRB-1 analysis.
Final results will be available soon: compatible with the time required by the
simulations and the analysis of the obtained results
LEADER Technical Meeting, Karlsruhe 2012
SIMMER III model: conclusions and
needed improvements
The model developed takes into account the real volume of the main
components of the ALFRED reactor, the flow areas and the axial
dimensions have been conserved.
The results will allow to evaluate:
• the pressure trends inside the ALFRED reactor
• the evaporated water flowing through the core
• the possible lead freezing
In the future work, one bayonet tube rupture in the ALFRED Steam
Generator will be analyzed by the axial-symmetric model developed by
the 2D SIMMER III code
LEADER Technical Meeting, Karlsruhe 2012