Safety Evaluation of VHTR Cogeneration System...for cogeneration of hydrogen and electricity • One...

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





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





- 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]


Pre cooler

Elapsed time from loss of the IS process thermal load [s]

150MWIHX

50MW

100MW

Concluding Remarks

Thanks for your [email protected]

• 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






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]


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]


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






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]


Thermal disturbanceIHX

2nd inlet

: +400 K

TurbineInlet

: +19.7 K

Turbine R.P.M. increase

: + 5 r.p.m.


2nd inlet

: +400 K

TurbineInlet

: +19.7 K


: + 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]


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


CompressorTurbine

PrimarySecondary

0

500

1000

1500

0 200 400 600 800 1000

Rea

ctor

out

let

tem

pera

ture

[K]


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


MAX: +0.19 MPa


: -34.0 kg/s


: -93.5 MW


: 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]



MAX: +0.16 MPa


: -59.7 kg/s


: -293 MW


: Constant


MAX: +0.16 MPa


: -59.7 kg/s


: -293 MW


: Constant


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

]


3800390040004100420043004400

020406080100

0 200 400 600 800 1000

Rot

atio

nal

spee

d [r

pm] C

V1 flow rate [kg/s]



2nd inlet

: +400 K

TurbineInlet

: +201 K


: + 90 r.p.m.


2nd inlet

: +400 K

TurbineInlet

: +201 K


: + 90 r.p.m.

Safety Evaluation of VHTR Cogeneration System...for cogeneration of hydrogen and electricity • One...

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