WP 1.5 Progress MeetingENEA – Bologna, Italy, May 28-30, 2008
ENTE PERLE NUOVE TECNOLOGIE,L’ENERGIA E L ’AMBIENTE
ENTE PERLE NUOVE TECNOLOGIE,L’ENERGIA E L ’AMBIENTE
FPN-FISNUC / Bologna
EUROTRANS – DM1
Analysis of Protected Accidental Transients in EFIT with RELAP5 Code
G. Bandini, P. Meloni, M. Polidori
2
ENTE PERLE NUOVE TECNOLOGIE,L’ENERGIA E L ’AMBIENTE
ENTE PERLE NUOVE TECNOLOGIE,L’ENERGIA E L ’AMBIENTE
EUROTRANS DM1 – WP 1.5 Progress Meeting, Bologna, May 28-30, 2008
Update of RELAP5 Model
22
112
173
UPPER PLENUMbranch120
110
LOWER PLENUMbranch 100
176 (177/8/9)175
6282
171
branch 160
Jun 106
InnerAverage
151
152153154
111
InnerHot
210211
OuterHot
OuterAverage
pipe281
282/3/4
SGswater side
Pumps113
DHR
Pth
pumpsplenumbranch
121
SGsPb side
SGsPb side
pipe381
382/3/4
annulus181
182/3/4
311310109
CoreMiddle
AverageMiddle
Hot
By pass&
reflector
branch
branchbranch
branch
03 010204050607
07 06 05 04 0203 01
01
01 0101
02
Jun 63Jun 23 Jun 83
Jun 104 Jun 114
01
05
06
01 02
22
112
170
UPPER PLENUMbranch120
110
LOWER PLENUMbranch 100
176 (177/8/9)175
6282
171
branch 160
Jun 106
InnerAverage
152153154
111
InnerHot
210211
OuterHot
OuterAverage
pipe281
282/3/4
SGswater side
113
DHR
Pth
SGsPb side
pipe381
382/3/4
annulus181
182/3/4
311310109
CoreMiddle
AverageMiddle
Hot
By pass&
reflector
branch
branchbranch
branch
03 010204050607
07 06 05 04 0203 01
01 0101
02
Jun 63Jun 23 Jun 83
Jun 104 Jun 114
01
05
06
01 02
0101
0108
108
Tar
get
lo
op
102
161
Jun 105
08
102
161
Jun 105
08
22
112
173
UPPER PLENUMbranch120
110
LOWER PLENUMbranch 100
176 (177/8/9)175
6282
171
branch 160
Jun 106
InnerAverage
151
152153154
111
InnerHot
210211
OuterHot
OuterAverage
pipe281
282/3/4
SGswater side
Pumps113
DHR
Pth
pumpsplenumbranch
121
SGsPb side
SGsPb side
pipe381
382/3/4
annulus181
182/3/4
311310109
CoreMiddle
AverageMiddle
Hot
By pass&
reflector
branch
branchbranch
branch
03 010204050607
07 06 05 04 0203 01
01
01 0101
02
Jun 63Jun 23 Jun 83
Jun 104 Jun 114
01
05
06
01 02
22
112
170
UPPER PLENUMbranch120
110
LOWER PLENUMbranch 100
176 (177/8/9)175
6282
171
branch 160
Jun 106
InnerAverage
152153154
111
InnerHot
210211
OuterHot
OuterAverage
pipe281
282/3/4
SGswater side
113
DHR
Pth
SGsPb side
pipe381
382/3/4
annulus181
182/3/4
311310109
CoreMiddle
AverageMiddle
Hot
By pass&
reflector
branch
branchbranch
branch
03 010204050607
07 06 05 04 0203 01
01 0101
02
Jun 63Jun 23 Jun 83
Jun 104 Jun 114
01
05
06
01 02
0101
01080108
108
Tar
get
lo
op
102
161
Jun 105
08
102
161
Jun 105
08
RELAP5 Nodalization Scheme
Primary system layout by D1.26 of ANSALDO (November 2007)
Primary circuit pressure drops according to new ANSALDO data
Gagging at core inlet according to SIM-ADS
DHR modeling data according to detailed ANSALDO analysis
3
ENTE PERLE NUOVE TECNOLOGIE,L’ENERGIA E L ’AMBIENTE
ENTE PERLE NUOVE TECNOLOGIE,L’ENERGIA E L ’AMBIENTE
EUROTRANS DM1 – WP 1.5 Progress Meeting, Bologna, May 28-30, 2008
PRIMARY SYSTEM: Total power = 395.2 MW Lead mass flowrate = 33243 kg/s Lead temperature = 400 / 480 C Total primary circuit pressure drop = 1.37 bar
(core = 0.7 bar, SG = 0.4 bar, Pump = 0.27 bar )
Total mass of lead = 5880 tons (ANSALDO data = 5954 tons)
Lead free levels = 1.085 / 1.495 / 0.448 (ANSALDO data = 1.085 / 1.473 / 0.406)
SECONDARY SYSTEM: Feedwater flow rate (4 SGs) = 244.4 kg/s, Temperature = 335 C Steam pressure = 140 bar Steam temperature = 452 C (Superheating of 115 C)
Main EFIT Parameters
4
ENTE PERLE NUOVE TECNOLOGIE,L’ENERGIA E L ’AMBIENTE
ENTE PERLE NUOVE TECNOLOGIE,L’ENERGIA E L ’AMBIENTE
EUROTRANS DM1 – WP 1.5 Progress Meeting, Bologna, May 28-30, 2008
RELAP5 Steady-State Calculation
Maximum temperature
(°C)
Inner zone (Fax = 1.14)
Middle zone (Fax = 1.16)
Outer zone (Fax = 1.17)
Hot FA 1/42 Fr = 1.12
Average FA 41/42
Hot FA 1/66 Fr = 1.13
Average FA 65/66
Hot FA 1/72
Fr = 1.24
Average FA 71/72
Central fuel 1251 1151 1329 1214 1284 1093
Surface fuel 870 818 858 804 816 734
Internal clad 539 524 535 519 534 508
External clad 527 513 524 510 525 501
Lead 494 484 494 483 502 482
Parameter Inner zone
Middle zone
Outer zone
Reflector Target Total
Thermal power (MW) 96 142.3 140.5 5.2 11.2 395.2
Lead mass flow rate (kg/s) 7678 11486 11445 1127 1506 33243
By-pass
outlet
Target
outlet
- -
- -
- -
- -
431 450
5
ENTE PERLE NUOVE TECNOLOGIE,L’ENERGIA E L ’AMBIENTE
ENTE PERLE NUOVE TECNOLOGIE,L’ENERGIA E L ’AMBIENTE
EUROTRANS DM1 – WP 1.5 Progress Meeting, Bologna, May 28-30, 2008
Transients to be Analyzed by ENEA (1)
TRANSIENT TO BE ANALYZED FOR PB-COOLED EFIT DESIGN
Number Transient Description BOC EOCENEA
RELAP5 (X-S) RELAP/PARCS (X-C)
SIMMER
PROTECTED TRANSIENTS
P-1 PLOFTotal loss of forced
circulation in primary system (4 pumps)
x xX-S (reactor trip on
pump speed threshold)
P-1.1 PLOF-1Loss of 1 out of 4
primary pumps (pump rotor seizure)
x xX-S (reactor trip on
core outlet temp. threshold)
P-4 PLOHTotal loss of secondary
loops (4 loops)x x
X-S (reactor trip on core outlet temp.
threshold)
P-4.1 PLOH-1loss of 1 out of 4 secondary loops
x xX-S (reactor trip on
core outlet temp. threshold)
P-5PLOF + PLOH
(station blackout)
Total loss of forced circulation and secondary loops
x xX-S (reactor trip
at 0 s)X (reactor trip at 0 s)
P-10Spurious beam
tripbeam trip for 1,2,3 …..
10 s intervalsx x X-C
P-11 SGTRSteam generator tube rupture (1 to 5 tubes)
xX (reactor trip at 0 s)
6
ENTE PERLE NUOVE TECNOLOGIE,L’ENERGIA E L ’AMBIENTE
ENTE PERLE NUOVE TECNOLOGIE,L’ENERGIA E L ’AMBIENTE
EUROTRANS DM1 – WP 1.5 Progress Meeting, Bologna, May 28-30, 2008
Analysis of Protected Transients
PLOF: Total loss of forced circulation (4 pumps)
PLOF-1: Stop of 1 pump (pump rotor seizure)
PLOH: Total Loss of Heat Sink
PLOH-1: Loss of feedwater to 1 steam Generator
PLOF + PLOH (Station blackout): Total loss of forced circulation and secondary loops with beam trip
PTOP: Overpower Transient (+10%)
REACTOR TRIP (Proton beam switch-off):
Core outlet temperature > 515 - 525 C (> DTass-max x 1.2 + 400 C)
Pump speed close to 0 (in case of total loss of forced circulation)
Delay in reactor trip = 2 s
7
ENTE PERLE NUOVE TECNOLOGIE,L’ENERGIA E L ’AMBIENTE
ENTE PERLE NUOVE TECNOLOGIE,L’ENERGIA E L ’AMBIENTE
EUROTRANS DM1 – WP 1.5 Progress Meeting, Bologna, May 28-30, 2008
Safety Limits
According to PDS-XADS safety analysis: Lead temperature always below 1500 C
Clad temperature below 550 C during normal operation
Clad temperature in the range:
550 – 600 C for less than 600 s,
600 – 650 C for less than 180 s,
in transient conditions
Vessel wall temperature below 450 C
8
ENTE PERLE NUOVE TECNOLOGIE,L’ENERGIA E L ’AMBIENTE
ENTE PERLE NUOVE TECNOLOGIE,L’ENERGIA E L ’AMBIENTE
EUROTRANS DM1 – WP 1.5 Progress Meeting, Bologna, May 28-30, 2008
Sensitivity Study on Reactor Trip Set-Points (1)
Accident Beam trip set-point Beam trip delay (s)
Beam Trip (s)
Maximum Tclad (s)
Maximum Tclad (C)
PLOF-0 (4 pumps)
Tlead ave-chan > 525 C (steady = 482 C)
2 12 12 845
PLOF (4 pumps)
Tlead ave-chan > 525 C (steady = 482 C)
0 10 11.4 821
PLOF-1a (4 pumps)
Tlead hot-chan > 525 C (steady = 502 C)
2 6.8 11.2 742
PLOF-1 (4 pumps)
Tlead hot-chan > 525 C (steady = 502 C)
0 4.8 10.8 683
PLOF-2 (4 pumps)
Tlead hot-chan > 515 C (steady = 502 C)
0 3.4 10.8 645
PLOF-3 (4 pumps)
Pump speed close to 0 2 2.8 10.8 630
PLOF-1p-0 (1 pump)
Tlead ave-chan > 525 C (steady = 482 C)
2 88 88 584
PLOF-1p (1 pump)
Tlead ave-chan > 525 C (steady = 482 C)
0 86 86 584
PLOF-1p-1a (1 pump)
Tlead hot-chan > 525 C (steady = 502 C)
2 10 10 566
PLOF-1p-1 (1 pump)
Tlead hot-chan > 525 C (steady = 502 C)
0 8 8 561
9
ENTE PERLE NUOVE TECNOLOGIE,L’ENERGIA E L ’AMBIENTE
ENTE PERLE NUOVE TECNOLOGIE,L’ENERGIA E L ’AMBIENTE
EUROTRANS DM1 – WP 1.5 Progress Meeting, Bologna, May 28-30, 2008
Sensitivity Study on Reactor Trip Set-Points (2)
Accident Beam trip set-point Beam trip delay (s)
Beam Trip (s)
Maximum Tclad (s)
Maximum Tclad (C)
PLOH-0 (4 SGs)
Tlead ave-chan > 525 C (steady = 482 C)
2 76 76 576
PLOH (4 SGs)
Tlead ave-chan > 525 C (steady = 482 C)
0 74 74 574
PLOH-1a (4 SGs)
Tlead hot-chan > 525 C (steady = 502 C)
2 53 53 556
PLOH-1 (4 SGs)
Tlead hot-chan > 525 C (steady = 502 C)
0 51 51 554
PLOH-1sg-0 (1 SGs)
Tlead ave-chan > 525 C (steady = 482 C)
2 340 340 573
PLOH-1sg (1 SGs)
Tlead ave-chan > 525 C (steady = 482 C)
0 338 338 573
PLOH-1sg-1a (1 SGs)
Tlead ave-chan > 525 C (steady = 482 C)
2 146 146 553
PLOH-1sg-1 (1 SGs)
Tlead hot-chan > 525 C (steady = 502 C)
0 144 144 553
PLOHS-0 (St-blackout)
Station-blackout at 0 s 0 0 11.4 566
10
ENTE PERLE NUOVE TECNOLOGIE,L’ENERGIA E L ’AMBIENTE
ENTE PERLE NUOVE TECNOLOGIE,L’ENERGIA E L ’AMBIENTE
EUROTRANS DM1 – WP 1.5 Progress Meeting, Bologna, May 28-30, 2008
PLOF + PLOH – Station Blackout (1)
Core Mass Flow Rate
-10000
0
10000
20000
30000
40000
-10 0 10 20 30 40 50Time (s)
Flo
w r
ate
(kg/
s)
mflowj 100080000
Lead Free Levels
0.4
0.6
0.8
1.0
1.2
1.4
1.6
-10 0 10 20 30 40 50Time (s)
Leve
l (m
)
cntrlvar 50
cntrlvar 51
cntrlvar 56
Vessel
Pump
Core
Lead free level fluctuations and stabilization after primary pump stop
Core mass flow rate reduces down to 0 in the initial transient
11
ENTE PERLE NUOVE TECNOLOGIE,L’ENERGIA E L ’AMBIENTE
ENTE PERLE NUOVE TECNOLOGIE,L’ENERGIA E L ’AMBIENTE
EUROTRANS DM1 – WP 1.5 Progress Meeting, Bologna, May 28-30, 2008
Pump Angular Velocity
-20
-10
0
10
20
-10 0 10 20 30 40 50Time (s)
Vel
ocity
(ra
d/s)
pmpvel 910
Pump Mass Flow Rate
-6000
-3000
0
3000
6000
9000
-10 0 10 20 30 40 50Time (s)
Flo
w r
ate
(kg/
s)
mflowj 910010000
PLOF + PLOH – Station Blackout (2)
Very fast pump coastdown due to low initial pump velocity and low moment of inertia
Pump velocity and mass flow rate reverse in the initial transient following lead free level stabilization
12
ENTE PERLE NUOVE TECNOLOGIE,L’ENERGIA E L ’AMBIENTE
ENTE PERLE NUOVE TECNOLOGIE,L’ENERGIA E L ’AMBIENTE
EUROTRANS DM1 – WP 1.5 Progress Meeting, Bologna, May 28-30, 2008
Max Clad Temperature
400
450
500
550
600
-10 0 10 20 30 40 50Time (s)
Tem
pera
ture
(C
)
httemp 111101216
httemp 211101216
httemp 311101216
Max Lead Temperature
400
450
500
550
600
-10 0 10 20 30 40 50Time (s)
Tem
pera
ture
(C
)
tempf 111180000
tempf 211180000
tempf 311180000
Outer coreMiddle coreInner core
Outer coreMiddle coreInner core
PLOF + PLOH – Station Blackout (3)
Maximum lead and clad peak temperature in hot channel of outer core zone
Maximum clad temperature is well below safety limits for transient conditions
13
ENTE PERLE NUOVE TECNOLOGIE,L’ENERGIA E L ’AMBIENTE
ENTE PERLE NUOVE TECNOLOGIE,L’ENERGIA E L ’AMBIENTE
EUROTRANS DM1 – WP 1.5 Progress Meeting, Bologna, May 28-30, 2008
Core and DHR Power
0.0E+00
5.0E+06
1.0E+07
1.5E+07
2.0E+07
2.5E+07
3.0E+07
0 1000 2000 3000 4000 5000Time (s)
Pow
er (
W)
cntrlvar 116
cntrlvar 131
Core and DHR Mass Flow Rates
0
1000
2000
3000
4000
5000
0 1000 2000 3000 4000 5000Time (s)
Flo
w r
ate
(kg/
s)
mflowj 100080000
mflowj 175010000
DHR
Core
DHR
Core
PLOF + PLOH – Station Blackout (4)
Natural circulation in the primary circuit and through the DHR stabilizes in about 500 s
Core decay power is totally removed by the DHR after about 1000 s
14
ENTE PERLE NUOVE TECNOLOGIE,L’ENERGIA E L ’AMBIENTE
ENTE PERLE NUOVE TECNOLOGIE,L’ENERGIA E L ’AMBIENTE
EUROTRANS DM1 – WP 1.5 Progress Meeting, Bologna, May 28-30, 2008
Lead Temperature
400
420
440
460
480
500
0 2000 4000 6000 8000 10000Time (s)
Tem
pera
ture
(C
)
tempf 100010000
tempf 120010000
tempf 175010000
tempf 113090000
DHR outCore in
DHR in
Core out (average)
Max Vessel Wall Temperature
400
410
420
430
440
450
0 2000 4000 6000 8000 10000Time (s)
Tem
pera
ture
(C
)
httemp 100100401
PLOF + PLOH – Station Blackout (5)
Primary hot lead temperature at core outlet stabilizes at about 453 C after 10000 s
Vessel wall temperature reaches a maximum of 435 C after 5000 s
15
ENTE PERLE NUOVE TECNOLOGIE,L’ENERGIA E L ’AMBIENTE
ENTE PERLE NUOVE TECNOLOGIE,L’ENERGIA E L ’AMBIENTE
EUROTRANS DM1 – WP 1.5 Progress Meeting, Bologna, May 28-30, 2008
PLOF – Total Loss of Forced Circulation (1)Pump Angular Velocity
-20
-10
0
10
20
-10 0 10 20 30 40 50Time (s)
Vel
ocity
(ra
d/s)
pmpvel 910
Core Mass Flow Rate
0
10000
20000
30000
40000
-10 0 10 20 30 40 50
Time (s)F
low
rat
e (k
g/s)
mflowj 100080000
Pump speed = 0 after 0.8 s Reactor trip with 2 s delay at 2.8 s
Initial core mass flow rate undershoot and fluctuations after primary pump stop
16
ENTE PERLE NUOVE TECNOLOGIE,L’ENERGIA E L ’AMBIENTE
ENTE PERLE NUOVE TECNOLOGIE,L’ENERGIA E L ’AMBIENTE
EUROTRANS DM1 – WP 1.5 Progress Meeting, Bologna, May 28-30, 2008
PLOF – Total Loss of Forced Circulation (2)Max Lead Temperature
400
450
500
550
600
650
-10 0 10 20 30 40 50Time (s)
Tem
pera
ture
(C
)
tempf 111180000
tempf 211180000
tempf 311180000
Max Clad Temperature
400
450
500
550
600
650
-10 0 10 20 30 40 50Time (s)
Tem
pera
ture
(C
)
httemp 111101216
httemp 211101216
httemp 311101216
Outer coreMiddle coreInner core
Outer coreMiddle coreInner core
Enhanced lead and clad temperature peaks after reactor trip at 2.8 s
Maximum clad temperature (hot channel of outer core) is below safety limits for transient conditions (less then 180 s in the range 600 – 650 C)
17
ENTE PERLE NUOVE TECNOLOGIE,L’ENERGIA E L ’AMBIENTE
ENTE PERLE NUOVE TECNOLOGIE,L’ENERGIA E L ’AMBIENTE
EUROTRANS DM1 – WP 1.5 Progress Meeting, Bologna, May 28-30, 2008
PLOF-1 – Stop of 1 Primary Pump (1)Pump Angular Velocity
0
5
10
15
20
25
-10 0 10 20 30 40 50Time (s)
Vel
ocity
(ra
d/s)
pmpvel 910
pmpvel 920
Lead Free Levels
0.4
0.6
0.8
1.0
1.2
1.4
1.6
-10 0 10 20 30 40 50Time (s)
Leve
l (m
)
cntrlvar 50
cntrlvar 51
cntrlvar 52
cntrlvar 56Vessel
Running pumps
Core
Stopped pump
Running pumps
Stopped pump
No reverse pump velocity is allowed after pump stop
Lead free level above stopped pump lies between vessel and core free levels after pump stop (reverse flow from vessel to core zone)
18
ENTE PERLE NUOVE TECNOLOGIE,L’ENERGIA E L ’AMBIENTE
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EUROTRANS DM1 – WP 1.5 Progress Meeting, Bologna, May 28-30, 2008
PLOF-1 – Stop of 1 Primary Pump (2)Pump Mass Flow Rate
-12000
-8000
-4000
0
4000
8000
12000
-10 0 10 20 30 40 50Time (s)
Flo
w r
ate
(kg/
s)
mflowj 910010000
mflowj 920010000
Core Mass Flow Rate
0
10000
20000
30000
40000
-10 0 10 20 30 40 50
Time (s)F
low
rat
e (k
g/s)
mflowj 100080000
Running pumps
Stopped pump
Slight increase in running pump mass flow rate and reverse flow through stopped pump
Core mass flow rate reduces by about 30%
19
ENTE PERLE NUOVE TECNOLOGIE,L’ENERGIA E L ’AMBIENTE
ENTE PERLE NUOVE TECNOLOGIE,L’ENERGIA E L ’AMBIENTE
EUROTRANS DM1 – WP 1.5 Progress Meeting, Bologna, May 28-30, 2008
PLOF-1 – Stop of 1 Primary Pump (3)Core In-Out Lead Temperature
325
375
425
475
525
575
-50 0 50 100 150 200 250 300Time (s)
Tem
pera
ture
(C
)
tempf 111180000
tempf 211180000
tempf 311180000
tempf 110180000
tempf 210180000
tempf 310180000
tempf 100010000
Core and SGs Extracted Power
0.E+00
1.E+08
2.E+08
3.E+08
4.E+08
5.E+08
-50 0 50 100 150 200 250 300Time (s)
Pow
er (
W)
cntrlvar 280
cntrlvar 116Core
SGs
Trip set-point
Reactor trip at 10 s (on hot channels T > trip set-point) or 86 s (on average channels T > trip set-point)
SG removal power decreases by about 12% after pump stop due to primary circuit mass flow rate reduction
Reactor trip onHot–average T-channel
20
ENTE PERLE NUOVE TECNOLOGIE,L’ENERGIA E L ’AMBIENTE
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EUROTRANS DM1 – WP 1.5 Progress Meeting, Bologna, May 28-30, 2008
PLOF-1 – Stop of 1 Primary Pump (4)Max Clad Temperature
350
400
450
500
550
600
-50 0 50 100 150 200 250 300Time (s)
Tem
pera
ture
(C
)
httemp 111101216
httemp 211101216
httemp 311101216
Max Fuel Temperature
400
600
800
1000
1200
1400
-50 0 50 100 150 200 250 300Time (s)
Tem
pera
ture
(C
)
httemp 111100701
httemp 211100701
httemp 311100701
Outer coreMiddle coreInner core
Outer coreMiddle coreInner core
Clad temperature is kept below safety limits for transient conditions (less than 600 s in the range 550 – 600 C)
Maximum fuel temperature is below acceptable value
21
ENTE PERLE NUOVE TECNOLOGIE,L’ENERGIA E L ’AMBIENTE
ENTE PERLE NUOVE TECNOLOGIE,L’ENERGIA E L ’AMBIENTE
EUROTRANS DM1 – WP 1.5 Progress Meeting, Bologna, May 28-30, 2008
PLOH – Total Loss of Heat Sink (1)Core In-Out Lead Temperature
325
375
425
475
525
575
-50 0 50 100 150 200 250 300Time (s)
Tem
pera
ture
(C
)
tempf 111180000
tempf 211180000
tempf 311180000
tempf 110180000
tempf 210180000
tempf 310180000
tempf 100010000
Max Clad Temperature
350
400
450
500
550
600
-50 0 50 100 150 200 250 300Time (s)
Tem
pera
ture
(C
)
httemp 111101216
httemp 211101216
httemp 311101216
Trip set-point
Outer coreMiddle coreInner core
Reactor trip at 53 s (on hot channels T > trip set-point) or 76 s (on average channels T > trip set-point)
Clad temperature is kept well below safety limits for transient conditions
Reactor trip onHot–average T-channel
22
ENTE PERLE NUOVE TECNOLOGIE,L’ENERGIA E L ’AMBIENTE
ENTE PERLE NUOVE TECNOLOGIE,L’ENERGIA E L ’AMBIENTE
EUROTRANS DM1 – WP 1.5 Progress Meeting, Bologna, May 28-30, 2008
PLOH – Total Loss of Heat Sink (2)Core and DHR Power
0.0E+00
5.0E+06
1.0E+07
1.5E+07
2.0E+07
2.5E+07
3.0E+07
0 2000 4000 6000 8000 10000Time (s)
Pow
er (
W)
cntrlvar 116
cntrlvar 131
DHR
Core
DHR mass flow rate stabilizes at approximately 3500 kg/s after about 3 hours
DHR system reaches maximum performances (about 20 MW for 3 units) after about 400 s
DHR Mass Flow Rate
0
1000
2000
3000
4000
5000
6000
0 2000 4000 6000 8000 10000Time (s)
Flo
w r
ate
(kg/
s)
mflowj 175020000
23
ENTE PERLE NUOVE TECNOLOGIE,L’ENERGIA E L ’AMBIENTE
ENTE PERLE NUOVE TECNOLOGIE,L’ENERGIA E L ’AMBIENTE
EUROTRANS DM1 – WP 1.5 Progress Meeting, Bologna, May 28-30, 2008
PLOH – Total Loss of Heat Sink (3)
Lead Temperature
400
420
440
460
480
500
0 2000 4000 6000 8000 10000Time (s)
Tem
pera
ture
(C
)
tempf 100010000
tempf 120010000
tempf 175010000
tempf 113090000
Max Vessel Wall Temperature
400
410
420
430
440
450
0 2000 4000 6000 8000 10000Time (s)
Tem
pera
ture
(C
)
httemp 100100401
DHR inCore outCore in
DHR out
Primary lead temperature stabilizes at about 435 C after 10000 s
Maximum vessel wall temperature around 3000 s is below safety limit (450 C)
24
ENTE PERLE NUOVE TECNOLOGIE,L’ENERGIA E L ’AMBIENTE
ENTE PERLE NUOVE TECNOLOGIE,L’ENERGIA E L ’AMBIENTE
EUROTRANS DM1 – WP 1.5 Progress Meeting, Bologna, May 28-30, 2008
Core and SGs Extracted Power
0.E+00
1.E+08
2.E+08
3.E+08
4.E+08
5.E+08
-200 0 200 400 600 800 1000 1200Time (s)
Pow
er (
W)
cntrlvar 280
cntrlvar 116
PLOH-1 – Loss of Feedwater to 1 SG (1)Core In-Out Lead Temperature
325
375
425
475
525
575
-200 0 200 400 600 800 1000 1200Time (s)
Tem
pera
ture
(C
)
tempf 111180000
tempf 211180000
tempf 311180000
tempf 110180000
tempf 210180000
tempf 310180000
tempf 100010000
Core
SGs
Reactor trip onHot–average T-channel
Trip set-point
Reactor trip at 146 s (on hot channels T > trip set-point) or 340 s (on average channels T > trip set-point)
SGs removal power reduces down to 75% at transient initiation
25
ENTE PERLE NUOVE TECNOLOGIE,L’ENERGIA E L ’AMBIENTE
ENTE PERLE NUOVE TECNOLOGIE,L’ENERGIA E L ’AMBIENTE
EUROTRANS DM1 – WP 1.5 Progress Meeting, Bologna, May 28-30, 2008
PLOH-1 – Loss of Feedwater to 1 SG (2)
Clad temperature is kept below safety limits for transient conditions (less than 600 s in the range 550 – 600 C)
Maximum fuel temperature is below acceptable value
Max Clad Temperature
350
400
450
500
550
600
-200 0 200 400 600 800 1000 1200Time (s)
Tem
pera
ture
(C
)
httemp 111101216
httemp 211101216
httemp 311101216
Max Fuel Temperature
400
600
800
1000
1200
1400
-200 0 200 400 600 800 1000 1200Time (s)
Tem
pera
ture
(C
)
httemp 111100701
httemp 211100701
httemp 311100701
Outer coreMiddle coreInner core
Outer coreMiddle coreInner core
26
ENTE PERLE NUOVE TECNOLOGIE,L’ENERGIA E L ’AMBIENTE
ENTE PERLE NUOVE TECNOLOGIE,L’ENERGIA E L ’AMBIENTE
EUROTRANS DM1 – WP 1.5 Progress Meeting, Bologna, May 28-30, 2008
PTOP – Overpower Transient (+10%)
Max Lead Temperature
Max Clad Temperature
Max Fuel Temperature
Core and SGs Power
27
ENTE PERLE NUOVE TECNOLOGIE,L’ENERGIA E L ’AMBIENTE
ENTE PERLE NUOVE TECNOLOGIE,L’ENERGIA E L ’AMBIENTE
EUROTRANS DM1 – WP 1.5 Progress Meeting, Bologna, May 28-30, 2008
CONCLUSIONS
Core decay heat removal by natural circulation through the DHR system is efficient in all investigated scenarios with total loss of heat removal by the secondary loops
Core and vessel structures temperatures are kept well below safety limits in all investigated protected scenarios even under the most conservative assumptions on reactor trip occurrence based on core outlet temperature measurements and trip set-point
Reactor trip on low pump rotational speed signal is needed in case of total loss of forced circulation in the primary circuit to keep clad temperature peak within acceptable values