Post on 16-Feb-2021
Safety Evaluation of VHTR Cogeneration System
Hiroyuki Sato, Tetsuo Nishihara, Xinglong Yan, Kazuhiko Kunitomi
Japan Atomic Energy Agency
IAEA International Conference on Non-electric Applications of Nuclear Power
18 April 2007 Oarai Japan
JAEA R&D for the VHTR system
High temperature operation (950℃) : 2004
Continuous hydrogen production 30NL/h 175hr : 2005
HTTR
IS Process
HTTR-IS system
World’s first demonstration of hydrogen production utilizing heat from nuclearpower
Hydrogen production rate : Around 1000 Nm3/h
Commercial VHTR systemCommercial VHTR system
Hydrogen production for commercial use
Economically competitive
2010 2030
GTHTR300C (170MWth for H2 plant)for Cogeneration of electricity and hydrogen
• Electricity generation : 202MWe• Hydrogen production rate : 25,000Nm3/h
GTHTR300C (370MWth for H2 plant)for Hydrogen production
• Hydrogen production rate : 52,000Nm3/h• Electricity generation for H2 plant
GTHTR300CGTHTR300C (170MWth for H2 plant)for Cogeneration of electricity and hydrogen
• Electricity generation : 202MWe• Hydrogen production rate : 25,000Nm3/h
GTHTR300CGTHTR300C (370MWth for H2 plant)for Hydrogen production
• Hydrogen production rate : 52,000Nm3/h• Electricity generation for H2 plant
Japanese Design of VHTR Cogeneration system
ReactorIHX
Precooler
Turbine
Generator
IS Process
Recuperator
Compressor
X. Yan et al., Proc. of 3rd information exchange meeting on nuclear production of hydrogen (2005).
950℃
900℃
Bird’s eye view of GTHTR300C
Heat Exchangers VesselReactor Pressure Vessel
Gas Turbine & IHX Vessel
2nd Loop He Circulator
Reactor Power Plant
IS Hydrogen Plant
HI Decomposition Facility Bunsen Reaction Facility
H2SO4 Decomposition Facility
Confinement Isolation Valves
GTHTR300C
Basic Design Philosophy of GHTHR300C
ReactorIHX
Precooler
Generator
IS Process
Recuperator
Non-nucleargrade
Nuclear grade
CompressorTurbine
Why Non-nuclear grade IS process ?Open the door to non-nuclear industries- IS process will be managed by oil and gas companies
Reducing the construction costs of the IS process- Apply the chemical plant design standard to the IS process
Why Non-nuclear grade IS process ?Open the door to non-nuclear industries- IS process will be managed by oil and gas companies
Reducing the construction costs of the IS process- Apply the chemical plant design standard to the IS process
Non-nuclear Design for IS process
a. Mitigate thermal load disturbanceoriginated by IS process
b. Protect the nuclear safety components from H2 explosion
c. Protect central control room of reactor against toxic gas
d. Reduce tritium concentration in 2ry helium loop and the IS process
a. Mitigate thermal load disturbanceoriginated by IS process
b. Protect the nuclear safety components from H2 explosion
c. Protect central control room of reactor against toxic gas
d. Reduce tritium concentration in 2ry helium loop and the IS process
Nuclear grade
Non-nuclear grade
b.
a.
c.
IS process Reactor facility
d.
Non-nuclear graded IS processNon-nuclear graded IS process
Safety philosophy for non-nuclear graded IS processSafety philosophy for non-nuclear graded IS process
Exempt the IS process from nuclear safety system
- Operate reactor normally under all conditions of the IS process -
Chemical reactor
Reactor
Primary System
2nd He gas system
IHX
Processapparatus
Turbo machine
Variation of thermal load
Turbine shutdown
Reactor scram
Mitigation system for controlling the turbine inlet temperature is requiredMitigation system for controlling the turbine inlet temperature is required
If mitigation system is not available
Variation of H2 Plant Thermal LoadMalfunction of equipments
e.g. pump, valve, control system
Variation of IHX outlet He temperature
Variation of turbine inlet temperature
Event Sequence of loss of thermal loadLoss of H2 plant
thermal load
Turbine inlet He temperature increase
Actuation of CV3
Turbine inlet temperature drop
Turbine inlet temperature controlled
Core flow rate decrease
Turbine over speed
Actuation of CV1
Turbine speed controlled
Reactor power controlled
TurbineCompressor
Precooler
Reactor
IHX
Recuperator
From H2Plant
To H2Plant
~
CV2CV1
CV3
V4
CV1 : Turbine bypass flow control valve
CV2 : Recuperator inlet temperature control valve
CV3 : Turbine inlet temperature control valve
V4 : Turbine bypass valve
Control of Reactivity
Dynamic Simulation Code for GTHTR300C
Component modelGas TurbineCompressorControl system
Reactor kineticsPoint nuclear kinetic equationReactor kinetics data
Thermal-hydraulic modelNon-condensable gas modelField equationsMass continuity, Momentum conservation,Energy conservation
Heat transfer correlation equationExperimental equation, Conventional equation
Compressor
TurbineIHX
Reactor core
Pre-cooler
Recuperator
CV3
CV1
CV2
VCSFlow Diagram of the Analytical Model of GTHTR300C
TurbineCompressor
Precooler
Reactor
IHX
Recuperator
From H2Plant
To H2Plant
~
CV2CV1
CV3
V4
CV1 : Turbine bypass flow control valve
CV2 : Recuperator inlet temperature control valve
CV3 : Turbine inlet temperature control valve
V4 : Turbine bypass valve
600
800
1000
1200
1400
IHX
seco
ndar
y in
let
heliu
m g
as
tem
pera
ture
[K]
1000
1050
1100
1150
1200
020406080100
Turb
ine
inle
t he
lium
gas
te
mpe
ratu
re [K
]
CV3 flow
rate [kg/s]
356035703580359036003610
0246810
0 200 400 600 800 1000Tur
bine
rota
tiona
l sp
eed
[rpm
] CV1 flow
rate [kg/s]
Elapsed time from loss of H2 plant load [s]
- Loss of thermal load of H2 Plant (170MW) in GTHTR300C -Dynamic Calculation (1/2)
Elapsed time from loss of the IS process thermal load [s]
19 K
5 rpm
0100200300400500
Hea
t tra
nsfe
r qu
antit
y [M
W]
280300320340360380
350400450500550600650
Rea
ctor
inle
t flo
w ra
te [k
g/s] R
eactor pow
er [MW
]
TurbineCompressor
Precooler
Reactor
IHX
Recuperator
From H2Plant
To H2Plant
~
CV2CV1
CV3
V4
CV1 : Turbine bypass flow control valve
CV2 : Recuperator inlet temperature control valve
CV3 : Turbine inlet temperature control valve
V4 : Turbine bypass valve
- Loss of Thermal Load of H2 Plant (170MW) in GTHTR300C -Dynamic Calculation (2/2)
0
500
1000
1500
0 200 400 600 800 1000
Rea
ctor
out
let
tem
pera
ture
[K]
Elapsed time from loss of H2 plant load [s]
Pre cooler
Elapsed time from loss of the IS process thermal load [s]
150MWIHX
50MW
100MW
Concluding Remarks
Thanks for your attention.sato.hiroyuki09@jaea.go.jp
• JAEA started the design study including the safety design of commercial VHTR systems GTHTR300C for cogeneration of hydrogen and electricity
• One of the key safety related events is to mitigate the effect of thermal load variation of hydrogen plant on the reactor system
• Plant dynamic calculation for loss of the H2 plant thermal load was performed
• Availability of the control system was verified
Back ground information
Control valve data
400A
400A
500A
Diameter
5.0 s (Including dead time 2.0s )
4679CV1
5.0 s(Including dead time 2.0s )
2070CV3
5.0 s(Including dead time 2.0s )
1202CV2
Acting timeCV value
(Shell side)
(800
Regenerative heat exchanger heat transfer correlation
( )
370090320
540180160
240
480
2
..
F.
...
He
ReDet
DeX.j
ReHW
DeX.j
HWWHDeDeλNuα
⎟⎠⎞
⎜⎝⎛
⎟⎠⎞
⎜⎝⎛=
⎟⎠⎞
⎜⎝⎛
⎟⎠⎞
⎜⎝⎛=
+==
U : Flow velocity
W : Flow path width of fins + fin thickness
H : Flow path height
X: Fin length
tf : Fin thickness [m]
( Re < 1000 )
( Re > 2000 )
(Helium side)
Pre-cooler Heat transfer correlation
in..
He DλPrRe.α40800230=
⎟⎠⎞
⎜⎝⎛+−=
⎟⎟⎠
⎞⎜⎜⎝
⎛⎟⎟⎠
⎞⎜⎜⎝
⎛⎟⎠⎞
⎜⎝⎛
⎟⎠⎞
⎜⎝⎛
⎟⎠⎞
⎜⎝⎛=
⋅= −
SDln..k
tD
DD
St
HS
DSRe.J
CPrCpGJα.
f
..f
..k
iW
034604150
2920771704730
0
666025701151
32
(Water side)
Din : Tube inner diameter [m]
Do : Tube outer diameter [m]
Cp : Specific heat [kJ/kg K]
Ci: Correction coefficient
S : Clearance between fins [m]
D : Fin outer diameter [m]
H : Fin height [m]
tf : Fin thickness [m]
G : Tube outer mass velocity [kg/s m2]
(Rotational speed)
Turbine model
ωFΣτΣdtωdI Σ iii −=
⎟⎟⎠
⎞⎜⎜⎝
⎛=
0CUfηt
RADπ
TNΦ
PTG
CU.Φ
ZπRTK
KgC
NDπU
mm
ii
i
.
KK
Ti
m
160
2080
11
2
60
251
0
1
0
=
⎟⎟⎠
⎞⎜⎜⎝
⎛=
⎟⎠⎞
⎜⎝⎛ −
−=
=
−
−
(Pressure ratio & Turbine Efficiency)
I : Inertia [kg m2]
ω : Rotational speed [rad/s]
τ: Shaft torque [Nm]
F : Friction coefficient (=0)
U : Turbine average circumferential velocity [m/s]
Dm : Turbine average diameter (=2m)
C0 :
K : Adiabatic index (=1.667)
Ti : Turbine inlet temperature [K]
πT : Pressure ratio
Z : Turbine stage (=6)
Cm : Turbine inlet axial velocity [m/s]
G : Turbine flow rate [kg/s]
Pi : Turbine inlet pressure [MPa]
Am : Turbine inlet flow area [m2]
Po : Turbine outlet pressure [MPa]
0
500
1000
1500
0
50
100
150
200
Turb
ine
inle
t he
lium
gas
te
mpe
ratu
re [K
]
CV3 flow
rate [kg/s]
TurbineCompressor
Precooler
Reactor
IHX
Recuperator
From H2Plant
To H2Plant
~
CV2CV1
CV3
V4
CV1 : Turbine bypass flow control valve
CV2 : Recuperator inlet temperature control valve
CV3 : Turbine inlet temperature control valve
V4 : Turbine bypass valve
- Loss of Thermal Load of H2 Plant (370MW) in GTHTR300C -Dynamic Calculation (3/4)
600
800
1000
1200
1400
IHX
seco
ndar
y in
let
heliu
m g
as
tem
pera
ture
[K]
3800390040004100420043004400
020406080100
0 200 400 600 800 1000
Rot
atio
nal
spee
d [r
pm] C
V1 flow rate [kg/s]
Elapsed time from loss of H2 plant load [s]
0100200300400500
-400
-200
0
200
400
Pre
cool
er
heat
tran
fer
quan
tity
[MW
]
IHX heat transfer quantity [M
W]
0
500
1000
1500
0 200 400 600 800 1000
Rea
ctor
out
let
tem
pera
ture
[K]
Elapsed time from loss of H2 plant load [s]
250300350400450500
0100200300400500600700
Rea
ctor
flow
in
let [
kg/s
] Reactor
power [M
W]
TurbineCompressor
Precooler
Reactor
IHX
Recuperator
From H2Plant
To H2Plant
~
CV2CV1
CV3
V4
CV1 : Turbine bypass flow control valve
CV2 : Recuperator inlet temperature control valve
CV3 : Turbine inlet temperature control valve
V4 : Turbine bypass valve
- Loss of Thermal Load of H2 Plant (370MW) in GTHTR300C -Dynamic Calculation (4/4)
IHX
Pre cooler
1000
1050
1100
1150
1200
020406080100
Turb
ine
inle
t he
lium
gas
te
mpe
ratu
re [K
]
CV3 flow
rate [kg/s]
- Loss of thermal load of H2 Plant (170MW) in GTHTR300C -
356035703580359036003610
0246810
0 200 400 600 800 1000Tur
bine
rota
tiona
l sp
eed
[rpm
] CV1 flow
rate [kg/s]
Elapsed time from loss of H2 plant load [s]
Thermal disturbanceIHX
2nd inlet
: +400 K
TurbineInlet
: +19.7 K
Turbine R.P.M. increase
: + 5 r.p.m.
Thermal disturbanceIHX
2nd inlet
: +400 K
TurbineInlet
: +19.7 K
Turbine R.P.M. increase
: + 5 r.p.m.
Dynamic calculation (1/4)
600
800
1000
1200
1400
IHX
seco
ndar
y in
let
heliu
m g
as
tem
pera
ture
[K]
- Loss of thermal load of H2 Plant (170MW) in GTHTR300C -
280300320340360380
350400450500550600650
Rea
ctor
inle
t flo
w ra
te [k
g/s] R
eactor pow
er [MW
]
4.44.64.8
55.25.4
0246810
IHX
heliu
m g
as
pres
sure
[MPa
] Pressure ratio
Dynamic calculation (2/4)
CompressorTurbine
PrimarySecondary
0
500
1000
1500
0 200 400 600 800 1000
Rea
ctor
out
let
tem
pera
ture
[K]
Elapsed time from loss of H2 plant load [s]
IHX pressure difference
MAX: +0.19 MPa
Reactor inlet flow rate variation
: -34.0 kg/s
Reactor power variation
: -93.5 MW
Reactor outlet temperature
: Constant
IHX pressure difference
MAX: +0.19 MPa
Reactor inlet flow rate variation
: -34.0 kg/s
Reactor power variation
: -93.5 MW
Reactor outlet temperature
: Constant
4
4.5
5
5.5
012345
IHX
heliu
m g
as
pres
sure
[MPa
] Pressure ratio
250300350400450500
0100200300400500600700
Rea
ctor
flow
in
let [
kg/s
] Reactor
power [M
W]
- Loss of thermal load of H2 Plant (370MW) in GTHTR300C -Dynamic calculation (4/4)
Primary
Secondary
CompressorTurbine
0
500
1000
1500
0 200 400 600 800 1000
Rea
ctor
out
let
tem
pera
ture
[K]
Elapsed time from loss of H2 plant load [s]
IHX pressure difference
MAX: +0.16 MPa
Reactor inlet flow rate variation
: -59.7 kg/s
Reactor power variation
: -293 MW
Reactor outlet temperature
: Constant
IHX pressure difference
MAX: +0.16 MPa
Reactor inlet flow rate variation
: -59.7 kg/s
Reactor power variation
: -293 MW
Reactor outlet temperature
: Constant
- Loss of thermal load of H2 Plant (370MW) in GTHTR300C -
100010501100115012001250
0
50
100
150
200
Turb
ine
inle
t he
lium
gas
te
mpe
ratu
re [K
]
CV3 flow
rate [kg/s]
600
800
1000
1200
1400IH
X se
cond
ary
inle
the
lium
gas
te
mpe
ratu
re [K
]
Dynamic calculation (3/4)
3800390040004100420043004400
020406080100
0 200 400 600 800 1000
Rot
atio
nal
spee
d [r
pm] C
V1 flow rate [kg/s]
Elapsed time from loss of H2 plant load [s]
Thermal disturbanceIHX
2nd inlet
: +400 K
TurbineInlet
: +201 K
Turbine R.P.M. increase
: + 90 r.p.m.
Thermal disturbanceIHX
2nd inlet
: +400 K
TurbineInlet
: +201 K
Turbine R.P.M. increase
: + 90 r.p.m.