Loading Pattern Optimisation - SFEN · LP OPTIMIZER DEVELOPMENT AT TRACTEBEL 28/06/2016 LOADING...
Transcript of Loading Pattern Optimisation - SFEN · LP OPTIMIZER DEVELOPMENT AT TRACTEBEL 28/06/2016 LOADING...
Confidential Restricted Public Internal
B. Vermeeren – 28 June 2016
Loading Pattern Optimization
Introduction
What is in-core fuel management?
What is loading pattern design?
What are the challenges?
LP Optimizer How does automated LP optimization work?
Development
at Tractebel How is LP Optimizer developed at Tractebel?
Outlook and
Conclusion
What will be improved?
What can we conclude?
CONTENTS
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Majority of nuclear power plants are operated in cycles, requiring periodic refueling due to fuel
depletion
Cycles of a nuclear power plant are designed to…
— Maintain safety margins for controlling and shutting down the reactor (= technical requirement)
— Maximize energy production (= economical requirement)
In-core fuel management ≡ calculating core reactivity, power distribution and isotopic inventory in
order to meet these technical and economical requirements during subsequent cycles
IN-CORE FUEL MANAGEMENT Introduction
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LOADING PATTERN DESIGN Introduction
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Loading pattern design ≡ find a suitable
configuration of fresh and irradiated FA (= fuel
assemblies) in order to meet the needs put
forward by in-core fuel management
Conventional tool for loading pattern design
(e.g. PANACHE*): User shuffles around irradiated
and fresh FA and modifies burnable poison
content in an attempt to comply to key safety
parameters
Challenging! Multi-dimensional, time-
dependent, non-linear combinatorial problem
* distributed by ANSWERS services UK
Loading pattern optimizer ≡ tool for automated optimization of an initial LP
≡ fast scoping of large search space
Introduction
What is in-core fuel management?
What is loading pattern design?
What are the challenges?
LP Optimizer How does automated LP optimization work?
Development
at Tractebel
How is LP Optimizer developed at Tractebel?
What are the results?
Outlook and
Conclusion
What will be improved?
What can we conclude?
CONTENTS
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Loading Pattern Optimizer (LPO) is a tool associated with PANTHER* (3D diffusion code for
steady-state and transient core calculations)
Simplified geometry to reduce PANTHER* evaluation time (1/4th or 1/8th core geometry, originally
using 2D condensed neutronic data libraries)
Specialized algorithms that perform well for discrete non-linear problems with a high number of
possible combinations (simulated annealing and genetic algorithms)
Further developed by Tractebel Engie (company in charge of engineering support for Belgian utility
operator Electrabel)
LOADING PATTERN OPTIMIZER
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How? By using optimization algorithms (simulated annealing or genetic algorithms) that…
Move around FA in core and between core and spent fuel pool
Change burnable poison content of fresh FA
Rotate/mirror FA to optimize burnup gradients
…in an attempt to minimize the objective function ≡ function which maps the quality of a LP on a
single variable that is minimized during the optimization (e.g. max. peak power)
Loading patterns which don’t comply to user set criteria penalize the objective function:
Economical criteria (min. natural cycle length, max. number of fresh fuel FA)
Safety criteria (max. peak power, max. MTC, max. FA burnup, …)
Positional criteria (Westinghouse guidelines, no highly irradiated FA under control rod bank D, …)
AUTOMATED LOADING PATTERN EVALUATION
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OBJECTIVE FUNCTION MINIMIZATION Max. peak power
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1.40
1.45
1.50
1.55
1.60
0 2000 4000 6000 8000 10000 12000
Max. P
eak P
ow
er
[-]
Loading Pattern Index [-]
Introduction
What is in-core fuel management?
What is loading pattern design?
What are the challenges?
LP Optimizer How does automated LP optimization work?
Development
at Tractebel
How is LP Optimizer developed at Tractebel?
What are the results?
Outlook and
Conclusion
What will be improved?
What can we conclude?
CONTENTS
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LP OPTIMIZER DEVELOPMENT AT TRACTEBEL
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LP OPTIMIZER LP REPORTER
PANACHE
PANTHER
Doc, id, conversion
On-screen shuffles
Better / best LP ?
First LP ?
AUTUNITE
Simplify user experience to allow usage in a production environment
— Easy user configuration and basic means for post-processing (facilitate search queries, …)
— Tight integration in a series of computer-aided loading pattern design tools used at Tractebel Engie
Transfer from 2D condensed neutronic data libraries to 3D calculations improves accuracy
LP OPTIMIZER DEVELOPMENT AT TRACTEBEL
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LP OPTIMIZER LP REPORTER
PANACHE
PANTHER
Doc, id, conversion
On-screen shuffles
Better / best LP ?
First LP ?
AUTUNITE
Simplify user experience to allow usage in a production environment
Transfer from 2D condensed neutronic data libraries to 3D calculations improves accuracy
— Possible due to increased availability of high performing CPUs
— Improved reproduction of axial behavior as trade-off with respect to increased loading pattern evaluation time
Simplify user experience to allow usage in a production environment
Transfer from 2D condensed neutronic data libraries to 3D calculations improves accuracy
Introduction of additional constraints to narrow down search space
— Limit maximum FA burnup
— Limit maximum peak power at Control Rod Insertion Limits
— Penalizing of objective function for specified combinations of FA positions and/or irradiation histories
— Accounting for Westinghouse guidelines for reshuffling of FA while optimizing burnup gradients (prevent
aggravation of in-core power tilt)
LP OPTIMIZER DEVELOPMENT AT TRACTEBEL
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LP OPTIMIZER DEVELOPMENT AT TRACTEBEL
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1.41
1.42
1.43
1.44
1.45
1.46
1.47
1.48
1.49
1.50
16200 16400 16600 16800 17000 17200 17400 17600 17800
Ob
jecti
ve F
un
cti
on
– M
ax.
Peak P
ow
er
[-]
Natural Length [MWd/tU]
LP OPTIMIZER DEVELOPMENT AT TRACTEBEL
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1.41
1.42
1.43
1.44
1.45
1.46
1.47
1.48
1.49
1.50
16200 16400 16600 16800 17000 17200 17400 17600 17800
Ob
jecti
ve F
un
cti
on
– M
ax.
Peak P
ow
er
[-]
Natural Length [MWd/tU]
large variety of
suitable
loading pattern
candidates
Optimization constraints:
Max. peak power ≤ 1.46
Max. MTC ≤ −2 pcm/°C
Max. # fresh FA ≤ 56
Min. natural cycle length ≥ 16.8 GWd/tU
Max. FA burnup ≤ 55 GWd/tU
No violation of Westinghouse guidelines
No highly irradiated FA under control
bank D
Introduction
What is in-core fuel management?
What is loading pattern design?
What are the challenges?
LP Optimizer How does automated LP optimization work?
Development
at Tractebel
How is LP Optimizer developed at Tractebel?
What are the results?
Outlook and
Conclusion
What will be improved?
What can we conclude?
CONTENTS
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Further improvement of user experience (e.g. library of preset configurations, direct visualization
of LPs)
Speed up optimization time (e.g. dynamic depletion scheme, parallel LP evaluation)
Multi-cycle optimization
Implementation of mechanical guidelines for Belgian loading pattern design (e.g. avoid
unfavorable FA orientations with respect to core baffle)
PLANNED DEVELOPMENT
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Loading Pattern Optimizer is a valuable new component to a series of computer-aided loading
pattern design tools at Tractebel
Generates large variety of suitable loading pattern candidates
LP Optimizer accommodates an increased demand for flexibility regarding in-core fuel
management and atypical, short-term loading pattern design
Simplified user setup allows deployment in a production environment
LP Optimizer supported a faster determination of suitable core loading pattern candidates in the
recent research for optimized restart of some of the Belgian nuclear power plants
CONCLUSION
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