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TRANSCRIPT
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PWR Heat Transfer & Fluid Flow
6 April 2011
Presentation to
ANSYS Info Day
Presented by
Chris Fry/Serco Technical Consultancy Services
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What is the connection between Serco and ANSYS?
Who are Serco?
Why have they been invited to give a presentation by ANSYS?
Need to look at history
Serco Public
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In the beginning things were simple
UKAEA
Developed reactor
concepts
NNC
Built reactors
CEGB
Operated
reactors
BNFL
Produced and
reprocessed fuel
Serco Public
concepts reactors reprocessed fuel
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Then Privatisation came along
UKAEA NNC CEGB BNFL
AEA Technology Nuclear
ElectricSellafield Ltd
Serco Public
AMEC
Electric
British
Energy
EDF
Energy
NNL
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Then Privatisation came along
UKAEA NNC CEGB BNFL
AEA Technology Nuclear
ElectricSellafield Ltd
Serco Public
AMEC
Electric
British
Energy
EDF
Energy
NNL
ANSYS
SERCO
CFDConsultants
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Introduction Heat transfer and fluid flow innuclear reactors
In a nuclear reactor the nuclear
reaction generates heat
Thereafter the engineering can be
considered as conventional
The removal of heat from the fuel is
vital for both operation and safety
Serco Public
vital for both operation and safety
Generation of heat continues even
after the reactor is shut down
The ability to reliably model heat
transfer and fluid flow is therefore
vitally important to the design and
safety justification of a nuclear
reactor
CFD should therefore have a central
place
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Introduction
In a nuclear reactor the nuclear
reaction generates heat
Thereafter the engineering can be
considered as conventional
The removal of heat from the fuel is
vital for both operation and safety
Serco Public
vital for both operation and safety
Generation of heat continues even
after the reactor is shut down
The ability to reliably model heat
transfer and fluid flow is therefore
vitally important to the design and
safety justification of a nuclear
reactor
CFD should therefore have a central
place
In practice it is not as central as you
might expect!
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The Current Role of CFD in Civil Nuclear Power
To understand the current role one has to look at the history of civil
nuclear power in the UK
Serco Public
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1st generation Magnox
11 reactors built in UK
Commissioned between 1956 and
1971
No CFD used in design or safety
case!
Serco Public
Fluid flow and heat transfer
calculations performed using:
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1st generation Magnox
11 reactors built in UK
Commissioned between 1956 and
1971
No CFD used in design or safety
case!
Serco Public
Fluid flow and heat transfer
calculations performed using:
Slide Rule!
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2nd Generation - AGR
7 reactors built in UK
Commissioned between 1976 and
1988
Fluid flow and heat transfer
calculations performed using:
Serco Public
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2nd Generation - AGR
7 reactors built in UK
Commissioned between 1976 and
1988
Fluid flow and heat transfer
calculations performed using:
Computers!
Serco Public
Computers!
But not CFD!
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3rd Generation - PWR
PWRs are the dominant reactor type
worldwide
First reactor (Shippingport US),
commissioned in 1957
Only 1 PWR in UK
Serco Public
Sizewell B commissioned in 1995
Established Westinghouse design
(with UK modifications)
Only limited amount of fluid flow
assessment therefore performed in
UK
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Thermal hydraulics analysis of PWRs
Original designs developed using slide rules and mainframe computers
Network computer codes developed to perform thermal hydraulic
calculations:
RELAP5
TRACE
Serco Public
TRACE
CONTAIN
MELCOR
Based on engineering correlations for heat transfer and fluid flow
derived from experiments
Single phase
Two phase
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Example of network code model
Serco Public
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Where is CFD being applied?
Where mixing occurs
Where the geometry is non standard
Where the flow pattern is complex:
e.g. counter-current flow
Serco Public
To support, rather than replace, the network codes
3 examples will be given
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Example 1 Boron Dilution
Serco Public
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ISP 43 A CFD code benchmark
Serco Public
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ISP-43 Test results
Serco Public
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ISP-43 Serco Results
60
70
80
Temperature (C)
Serco Public
20
30
40
50
0 100 200 300 400 500 600
Total Flow (l)
Temperature (C)
CFX-4 calculation
Nominal test
Repeat test
Repeat test
Repeat test
Repeat test
Data from one repeat test
not available
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ISP-43 all CFD results
level 4 average
55
60
65
70
75
temperature (deg. C)
Serco Public
25
30
35
40
45
50
10 15 20 25 30 35 40 45 50 55 60time (s)
temperature (deg. C)
test B AEAT
CEAkeps CEAnut0
CEAnut0p IVO
NRI NUPEC
NRC Vattenfall
ensemble B viz
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Example 2 Temperature of a boiler bifurcation
Hot gas
Serco Public
Steam
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Boiler tube CFD model
Hot gas
Serco Public
Steam
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Boiler tube results external flow and HTC
Serco Public
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Boiler tube results internal flow and HTC
Serco Public
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Boiler tube results tube temperature
Serco Public
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Example 3 hydrogen control in a VVER-440
Serco Public
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Hydrogen control CFD model
Serco Public
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Hydrogen control hydrogen concentration
Serco Public
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Hydrogen control amount of hydrogen recombined
Serco Public
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Hydrogen control effect of condensation
Serco Public
Without pool wall condensation With pool wall condensation
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Other Issues
Two phase CFD
Use of best practice guidelines
CFD4NRS
Collaboration in international exercises
Serco Public
Mistrust of CFD
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Use of CFD for assessing PWR thermal hydraulics the future
An important (but not dominant) role
Increased use of passive safety features (e.g. natural convection)
Integration with network codes
Serco Public
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Conclusions
The current role of CFD in assessing heat transfer and fluid flow in
Pressurised Water (and other) Reactors has been described.
Flow analysis dominated by network codes
However CFD still has an important (and slowly growing) contribution
to make
Serco Public
to make