dynamic response to pulsed beam operation in accelerator driven subcritical reactors
DESCRIPTION
Dynamic Response to Pulsed Beam Operation in Accelerator Driven Subcritical Reactors . Ali Ahmad Supervisor: Dr Geoff Parks University Nuclear Technology Forum April, 2011. Overview. Introduction Characterisation of the dynamic response in ADSR The PTS-ADS code - PowerPoint PPT PresentationTRANSCRIPT
Dynamic Response to Pulsed Beam Operation
in Accelerator Driven Subcritical Reactors
Ali Ahmad
Supervisor: Dr Geoff Parks
University Nuclear Technology Forum
April, 2011
UNTF 2011 Ali Ahmad
Overview
• Introduction
• Characterisation of the dynamic response in ADSR
• The PTS-ADS code
• The thermo-mechanical stress analysis in the fuel cladding
UNTF 2011 Ali Ahmad
Introduction
“Fukushima disaster causes fallout for nuclear industry worldwide” The Guardian 29 March 2011
“The world energy demand is expected to grow by approx 50% from 2007 to 2035” International Energy Outlook 2010, US EIA
Safety
Sustainability
Agenda
UNTF 2011 Ali Ahmad
Characterisation of the dynamic response in ADSR
FFAG accelerator seems to be the most suitable option for ADSR because:
- High beam intensity- High efficiency of power consumption- High stability in operation- Cheaper than Linac
FFAG works in a pulsed mode
Frequent core temperature variations
Thermal cyclic fatigue in the cladding?
Agenda
UNTF 2011 Ali Ahmad
The PTS-ADS code
Agenda
UNTF 2011 Ali Ahmad
The PTS-ADS code: Fuel Pin Heat Transfer Model
Assumptions:
1- The axial power distribution has a sinusoidal form
2- The heat generation rate is uniform across the radial direction inside the fuel
3- Heat transfer only occurs in the radial direction
The fuel pin heat equation can be written as:
'''1 qrTkr
rrtTCp
UNTF 2011 Ali Ahmad
The PTS-ADS code: Neutronic Model
Six-group Point Kinetics model:
6
1
)()()()()(i
ii tStCtPtttP
)()()( tCtPttC
iiii
)()()0()( CoolantCoolantfuelDoppler TTt
Total reactivity can be written as:
UNTF 2011 Ali Ahmad
The PTS-ADS code: Validation Case Study
Benchmark study on beam interruptions in XADS
The PTS-ADS coupled model was compared to three other codes selected from a benchmark study on beam interruption for the Experimental ADS* (80 MWt, MOX, Lead-Bismuth coolant).
- TRAC-MOD- SIMADS- SAS4ADS
*) A. D’Angelo et al. Benchmark on beam interruptions in an accelerator driven system final report on phase I calculations, Tech. Rep. NEA/NSC/DOC(2003)17, NEA (2003).
UNTF 2011 Ali Ahmad
The PTS-ADS code: Validation Case Study
UNTF 2011 Ali Ahmad
The PTS-ADS code: Validation Case Study
UNTF 2011 Ali Ahmad
The PTS-ADS code: Validation Case Study
UNTF 2011 Ali Ahmad
The PTS-ADS code: Validation Case Study
UNTF 2011 Ali Ahmad
The thermo-mechanical stress analysis in the fuel cladding
Fuel pin geometry and the physical properties of the fuel, cladding and coolant materials are taken from the XADS data sheet.
972.0effk
Beam characteristics: - Frequency 1 Hz - Beam off time 10, 50 and 100 ms
Local linear power: - 9172 W/m (XADS ref case) - 2500 W/m (Industrial ADSR)
Agenda
UNTF 2011 Ali Ahmad
The thermo-mechanical stress analysis in the fuel claddingLife prediction of the fuel pin cladding
In a nuclear reactor, the integrity of the structural materials in general and of the fuel cladding in particular is of high importance.
Cladding failure Fission products leakage to the primary coolant circuit
The thermal stress on the cladding can be calculated using:
12T
EDefine the stress amplitude:
2minmax
a
The stress amplitude is related to the failure limit Nf by Basquin’s Law:
bffa N )2('
where is the fatigue strength coefficient and b is the fatigue strength exponent
'f
UNTF 2011 Ali Ahmad
The thermo-mechanical stress analysis in the fuel cladding
Both and b can be estimated experimentally for certain materials at certain temperatures.
The cladding material in this study is T91 stainless steel.
'f
Temperature(°C) (MPa) (MPa)
b
300 0.24 695 −0.052 Indefinite
550 0.7 649 −0.093 Indefinite
a 'f
fN
UNTF 2011 Ali Ahmad
Conclusions
The integrity of the fuel cladding of an ADSR can be assumed to be unaffected by the repetitive temperature fluctuations due to pulsed operation mode.
UNTF 2011 Ali Ahmad
Future Work
• Use the PTS-ADS code to measure the temperature variations in the fuel cladding when subjected to beam interruptions (t> 1 second) and predict the stress-life behaviour for that case
• Study the influence of other factors such as radiation damage and creep on the cladding fatigue life
• Further development of the PTS-ADS code to include the ability study all ADSR transients and for different core configurations