FIRE SAFETY SIMULATION OF CABLE FIRE IN NUCLEAR POWER...
Transcript of FIRE SAFETY SIMULATION OF CABLE FIRE IN NUCLEAR POWER...
FIRE SAFETY SIMULATION OF
CABLE FIRE IN NUCLEAR
POWER PLANT ROOM BASED
ON FLAMMABILITY DATABASE
OF CABLES
Akihiro Matsuda
Department of Engineering Mechanics and Energy
University of Tsukuba
SMiRT23 Manchester UK 2015
CONTENTS
• Objectives
• Flammability tests of electrical cables
• Evaluation by the Arrhenius equation
• CFD analysis with FDS
• Conclusion
This research was supported by research fund from Japan Nuclear Energy Safety Organization(JNES -> NRA,Japan)
OBJECTIVE
• Develop the safety evaluation method of nuclear
power plant cables in fire accidents
• Flammability test of cables in high temperature to
verify electrical performance of cable
• Effect of cable temperature on insulation
resistance and short circuit time
• CFD simulation of switchgear room in fire accident
• Temperature distribution of switchgear room was
computed
• Flammability test machine
• Develop by modifying cone-calorimeter machine
• Temperature of cone heater was controlled digitally
• 1~5 cables on cable tray are possible to test
• Maximum temperature of cone heater is 800℃
TEST FACILITIES
Heat chamber
Heat release rate
PC
• Cable specimens for flammability test
• Cable tray specimen with electrical cables are applicable to
flammability test
• Surface temperature of cable was controlled by laser type
temperature sensor
• Length of cables was 620mm
CABLE SPECIMENS FOR TEST
Cone heater
Cable tray
Cable
INSULATION RESISTANCE IN
FLAMMABILITY TEST
• Insulation resistance in flammability test
• Between insulators, insulator and tray
• Hyper electrical resistance measurement machine
• Capacity of insulation resistance from 2.0 to 1.0x107M
• Ignition of cables were observed in high temperature
Ω
Heater Cable
SM-8215 HIOKI Corp. Japan
CABLES FOR FLAMMABILITY
TESTS
• Cables used in nuclear plants were applied to
flammability test
• SHCVV
• SPVV
• FR-STP
• CCSHV
SPECIFICATION OF CABLES
Name of cable Sheath Insulator
Number
Of
Conductor
DiameterIEE
E383
1.SHCVV HR-vinyl HR-vinyl 8 14mm
2.SPVVPolyvinyl
chloride
Polyvinyl
Chloride2 9mm
3.FR-STP FR-EP rubber FR-HR vinyl 2 10.5mm ○
4.CCSHVCross linked
polyethyleneVinyl 2 9mm
IEEE383: Vertical flame tray test
101
102
103
104
105
106
107
108
Insu
lati
on
res
ista
nce
(MΩ
)
120100806040200
Time (min)
200℃ 220℃ 240℃ 280℃ 340℃ 400℃ 460℃ 550℃
800
600
400
200
Cab
le t
emper
ature
(℃
)
80006000400020000
Time (sec)
200℃ 220℃ 240℃ 280℃ 340℃ 400℃ 460℃ 550℃
TEST RESULTS OF SHCVV
Name of cable Sheath Insulator
Number
Of
Conductor
Diameter
1.SHCVV HR-vinyl HR-vinyl 8 14mm
200℃
800
600
400
200
Cab
le t
emper
ature
(℃
)
120100806040200
Time (min)
220℃ 240℃ 260℃ 320℃ 380℃ 440℃ 530℃
101
102
103
104
105
106
107
108
Insu
lati
on r
esis
tance
(MΩ
)
120100806040200
Time (min)
220℃ 240℃ 260℃ 320℃ 380℃ 440℃ 530℃
Name of cable Sheath Insulator
Number
Of
Conductor
Diameter
2.SPVVPolyvinyl
chloride
Polyvinyl
Chloride2 9mm
TEST RESULTS OF SPVV
220℃
Name of cable Sheath Insulator
Number
Of
Conductor
Diameter
3.FR-STP FR-EP rubber FR-HR vinyl 2 10.5mm
TEST RESULTS OF FR-STP
800
600
400
200
Cab
le t
emp
erat
ure
(℃
)
120100806040200
Time (min)
310℃ 330℃ 390℃ 450℃ 540℃ 590℃
101
102
103
104
105
106
107
108
Insu
lati
on
res
ista
nce
(MΩ
)
120100806040200
Time (min)
310℃ 330℃ 390℃ 450℃ 540℃
310℃
Name of cable Sheath Insulator
Number
Of
Conductor
Diameter
4.CCSHVCross linked
polyethyleneVinyl 2 9mm
TEST RESULTS OF CCSHV
800
600
400
200
Cab
le t
emp
erat
ure
(℃
)
120100806040200
Time (min)
340℃ 360℃ 380℃ 400℃ 490℃ 540℃
101
102
103
104
105
106
107
108
Insu
lati
on
res
ista
nce
(MΩ
)
120100806040200
Time (min)
340℃ 360℃ 380℃ 400℃ 490℃ 540℃
340℃
RELATIONSHIPS BETWEEN SHORT-
CIRCUIT TIME AND CABLE
TEMPERATURE (CABLE 1~4)
700
600
500
400
300
200
100
0
Cab
le t
emp
erat
ure
(℃
)
12 3 4 5 6 7 8 9
102 3 4 5 6 7 8 9
1002
Short circuit time (min)
SHCVV
SPVV
FR-STP
CCSHV
• Relationships between short circuit times and surface
temperature of cables were summarized
• θ= θ∞+(θb -θ∞) exp(α・t)
• θb : Temperature of ignition
• θ∞ : Temperature which reach
2h without short-circuit
• α: Parameter of each cables
Test results of every cables showed faster short circuit time as temperature higher.
Fundamental behavior of electrical characteristics and effects of temperature were obtained.
EVALUATION BY ARRHENIUS
EQUATION
• Applicability of the Arrhenius equation to flammability
test was investigated
• Plot the relation ships between ln(TR) and reciprocal of
θ(1/θ(K)) in same insulation resistance
• Short circuit, 10MΩ, 100MΩ were selected
101
102
103
104
105
106
107
108
Insu
lati
on
res
ista
nce
(MΩ
)
120100806040200
Time (min)
200℃ 220℃ 240℃ 280℃ 340℃ 400℃ 460℃ 550℃
100MΩ
10MΩ
TR
θ
Short circuit
ARRHENIUS PLOT OF SHCVV
AND SPVV
• Plots of SHCVV and SPVV show linear relationships between
ln(TR) and 1/θ(K)
6
5
4
3
2
1
0
-1
ln(T
R)
2.52.01.51.0
1/θ (10-3
/K)
短絡10MΩ100MΩ
○ short circuit
□ 10MΩ
△ 100MΩ
5
4
3
2
1
0
-1
-2
-3
ln(T
R)
2.01.51.0
1/θ (10-3
/K)
短絡10MΩ100MΩ
○ short circuit
□ 10MΩ
△ 100MΩ
SHCVV SPVV
3
2
1
0
ln(T
R)
1.61.41.2
1/θ (10-3
/K)
短絡10MΩ100MΩ
5
4
3
2
1
0
-1
ln(T
R)
2.01.51.0
1/θ (10-3
/K)
短絡10MΩ100MΩ
ARRHENIUS PLOT OF FR-STP
AND CCSHV• Arrhenius plot of FR-STP and CCSHV show linear
relationships between ln(TR) and 1/θ(K)
• The Arrhenius equation was applicable to flammability
test○ short circuit
□ 10MΩ
△ 100MΩ
○ short circuit
□ 10MΩ
△ 100MΩ
FR-STP CCSHV
CFD ANALYSIS BY FDS
• FDS: Fire Dynamics Simulator
• Developed by NIST(National Institute of Standards and Technology, USA)
• Solve the Navire-Stokes equation
• Large Eddy simulation for turbulence flow
• Input heat release rate for fire source
• In this simulation, an electrical cabinet fire was supposed
• A switchgear room was selected
• Specification of room was based on Nuclear Power Plant Fire Modeling
Application Guideline(NPP FIRE MAG), NUREG-1934( 2011)
SWITCH GEAR ROOM FOR
SIMULATION
• Mesh model for switchgear room was created in FDS
• Switchgear room and cable tray were applied to CFD model
• Ventilation was supposed as design value
• Fire from electrical cabinet was assumed
NUREG-1934( 2011) CFD model
• For fire-source, burning test results of electrical cabinet
were applied.
• 0.3m x 0.6m of the upper surface of electrical cabinet was
supposed as the fire-source, duration time was 40min.
HEAR RELEASE RATE FOR
NUMERICAL ANALYSIS
1000
800
600
400
200
0
Hea
t re
leas
e ra
te(k
W)
25002000150010005000
Time(s)
Nuclear Power Plant Fire Modeling Application Guideline(NPP FIRE MAG), NUREG-1934( 2011)
SNAPSHOTS OF CFD ANALYSIS
1000
800
600
400
200
0
Hea
t re
leas
e ra
te(k
W)
25002000150010005000
Time(s)
• Time of snapshot was 1100sec.
• Maximum temperature was
observed in CFD simulation
Temperature distribution Velocity of air
EVALUATION OF
CABLE TEMPERATURE
800
600
400
200
0
Tem
per
ature
(゜C
)
70605040302010
Distance from fire source(cm)
• Maximum cable temperature showed higher as distance
from the fire source closer
• Duration time of this simulation case was short for long-
time short circuit.
• In this case, 400℃ was supposed as the temperature of
immediate short circuit.
CONCLUSION
• The safety evaluation method of cables in nuclear plant fire accidents was developed
• Electrical performance test of cables in high temperature were conducted
• Relationships between temperature and short circuit time was proposed
• CFD simulation(FDS) to know temperature distribution of cables in nuclear power plant room
• Safety distance from fire source was able to be investigated by CFD simulation
• Performance of cables in high temperature were able to investigate by flammability test and CFD simulation
800
600
400
200
Cab
le t
emp
erat
ure
(℃
)
120100806040200
Time (min)
380℃ 390℃ 410℃ 430℃ 470℃ 490℃
Name of cable Sheath Insulator
Number
Of
Conductor
Diameter
5.Eco-material PolyethyleneFR-
Polyethylene2 10mm
TEST RESULTS OF EMC
380℃
101
102
103
104
105
106
107
108
Insu
lati
on
res
ista
nce
(MΩ
)
120100806040200
Time (min)
380℃ 390℃ 410℃ 430℃ 470℃ 490℃
800
600
400
200
Cab
le t
emp
erat
ure
(℃
)
120100806040200
Time (min)
430℃ 450℃ 470℃ 490℃ 530℃ 550℃ 570℃
Name of cable Sheath Insulator
Number
Of
Conductor
Diameter
6.Non-halogen FR-Polyethylene Polyethylene 2 10mm
TEST RESULTS OF NH
430℃
101
102
103
104
105
106
107
108
Insu
lati
on
res
ista
nce
(MΩ
)
120100806040200
Time (min)
430℃ 450℃ 470℃ 490℃ 530℃ 550℃ 570℃
EFFECT OF HEATED AREA ON
INSULATED RESISTANCE
R1
R2
R3
321
111
1
RRR
R
3
1RR
321 RRR
• Heated area of flammability test was increased
• Heated area was double and triple of normal test
• Insulated resistance was evaluated
RELATIONSHIPS BETWEEN SHORT-
CIRCUIT TIME AND CABLE
TEMPERATURE(EMC AND NHC)
• Relationships between short circuit times and surface
temperature of cables were summarized
• θ= θ∞+(θb -θ∞) exp(α・t)
• θb : Temperature of ignition
• θ∞ : Temperature which reach
2h without short-circuit
• α: Parameter of each cables
Test results of every cables showed faster short circuit time as temperature higher.
Fundamental behavior of electrical characteristics and effects of temperature were obtained.
700
600
500
400
300
200
100
0
Cab
le t
emp
erat
ure
(℃
)
12 3 4 5 6 7 8 9
102 3 4 5 6 7 8 9
1002
Short circuit time (min)
EMC
NHC
SHCVV
0
100
200
300
400
500
600
EMC NHC SHCVV SPVV FR-STP CCSHV
Ca
ble
tem
per
atu
re(℃
)
Cable
安全温度
発火温度
TEMPERATURE Θ∞
AND ΘB
θ∞
θb
θb
θ∞
EFFECT OF HEATED AREA ON
INSULATED RESISTANCE
• Cable specimen was fixed on cable tray
• Length of cable was 1800mm
• Cable was bended and 2 and 3 part of cable were under the heater
Φ180
TEST RESULTS
• Insulated resistance became 1/2 and 1/3, when
heated area were double and triple.
101
102
103
104
105
106
107
108
Insu
lati
on
res
ista
nce
(MΩ
)
120100806040200
Time (min)
直線 2つ折り 3つ折り
○ Straight
□ Double area (x2)
△ Triple area (x3)
Θ=290℃
101
102
103
104
105
106
107
108
Insu
lati
on
res
ista
nce
(MΩ
)
50403020100
Time (min)
直線 2つ折り 3つ折り
EFFECT OF HEATED AREA ON
SHORT CIRCUIT TIME
• The heated area increases, short circuit time
became shorter
○ Straight
□ Double area (x2)
△ Triple area (x3)
Θ=390℃
CONCLUSION
• Fire damage testing of electric cables in nuclear
plants was conducted
• Flammability test of cables in high temperature
• Relationships between temperature and short
circuit time was investigated
• Relationships between heated time and
temperature was evaluated by the Arrhenius
equation
FUTURE WORK
• Establish estimation method of insulation
resistance of cable in fire accidents
• Modeling of relationship between insulation
resistance and time under various temperature
would be investigated