Next Generation Reactor Physics Code Development · Shielding codes will not be discussed in this...

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IAEA Workshop on Advanced Code Suite For Design, Safety Analysis And Operation Of Heavy Water Reactors

(2-5 October, 2012, Ottawa, Marriott Hotel)

Dr. Alexandre Trottier (AECL, Chalk River Laboratories, Computational Reactor

Physics Branch)

AECL’s Next Generation

Reactor Physics Code

Development Program

Outline

Introduction

Mesh-free approach

Other efforts

Summary

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AECL reactor physics codes

Reactors of interest

Challenges

Program objectives


Introduction

Physics Codes at AECL

Lattice codes

WIMS-AECL

DRAGON


Core codes

RFSP

TRIAD3

Other

WOBI

MCNP5

SERPENT

SCALE6

Shielding codes will

not be discussed in

this talk.

AECL’s Reactor Physics Computational

Scheme


Three-Level Deterministic

Calculations


Basic Lattice Properties

2D Lattice Cell Transport Calculation

Reactivity Devices

3D Super-Cell Transport Calculation

3D Reactor Diffusion Calculation

Steady State, Kinetics, Dynamics, etc.

Reactors of interest – ZED-2

Critical facility

Low-power & flux

– 5 W to 200 W

D2O-moderated tank

Aluminum vessel

Fuel lengths 250 cm to

300 cm


227 sites

–18 control rods

–4 adjuster rods

84 – 93 driver fuel

rods.

2 loops for fuel

bundle testing

5 to 13 Mo-99 rods


Reactors of Interest – NRU

Reactors of interest – SCWR

Direct cycle

Light water cooled

–25 MPa coolant pressure

–350°C inlet T

–650°C outlet T

Heavy water moderated

Strong axial gradients


Reactors of interest – Current Canadian

Power Reactors...


Challenges

Workforce demographics

Reactor design multiplicity

Legacy coding

Desire for an integrated code

Critical test facility capability maintenance

Critical test data for future fuel designs


Some Specific Limitations in AECL

Physics Codes

Difficult to integrate within projected reactor code suite

Parallel computing not enabled for most codes

WIMS-AECL is 2D

RFSP and TRIAD3 are design specific

Calculation scheme is challenged for Th-based fuels

No deterministic uncertainty quantification capability



Physics Code Development Objectives

Stand-alone or integrated operation with AECL reactor

code suite

Parallel computing for deterministic codes

Enable 3D lattice calculations

A core code for any thermal reactor, any fuel

Deterministic uncertainty quantification

Why should we ?

How could we do it ?

Feasibility study

Current efforts


Mesh-Free Methods

WIMS-AECL versus Other Codes

WIMS-AECL

Number of meshes: < 500

Computing time: < 30 s

15

TRITON/NEWT (SCALE)

Number of meshes: > 3600

Computing time: ~ 45 min

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A New Approximation Approach


Eliminate meshing and specify an approximate solution

according to geometric shape of material regions

What is an R-Function?

Simple definition

Real continuous function, the properties of which depend on

the properties of its arguments.

Properties of interest

Objective

Analytical description of complex spatial domains.

Application

Numerical solution of boundary value problems.


Three-valued logical algebra

Mathematical Description of Complex Domain

Euler diagrams as an illustration of set operators action


Complement Intersection Union

R-Function Solid Modeling


Set operators and R-operators correspondence

Explicit form of R-operators (R0 system)

Domain Functions

Consider each material region

Vi as a distinct spatial domain

specified by a function i.

Cylindrical domains V2, V3, V0:

Complex domain V1:


Domain Function of Moderator Region


Reference Solution


Energy Group # 1 Energy Group # 75

Continuous flux reconstruction using the integral transport equation applied to

fine-mesh solution obtained by collision probability method.

Group-wise Error in Flux Distribution


Approximate versus Reference Solution


Mesh-Free Lattice Physics

R-Function approach can express the flux solution

Now need to calculate it

Currently investigating the 2nd order even-parity

formulation

Some difficulties in approximating the high-order

harmonics with R-functions


An Illustration of Angular Moments Shape


Infinite Square Lattice of Cylindrical Fuel Elements

Spatial Distribution in Energy Group # 78 (Thermal Peak)

Zero order moment 1st order moment (cosine term)

Low Order Spherical Harmonics Moments


Increasing the order, the spherical harmonics moments take

more complicated shape s.

2nd order moment 3rd order moment

Mesh-Free Diffusion Code

Solver for multigroup neutron diffusion equation

Variational formulation, using R-function method – D.V. Altiparmakov, Nucl. Sci. Eng. 92, 330-337 (1986)

Designed for maximum geometric flexibility

Just started development

–2D/3D benchmark geometry

–multigroup cross sections

–Fortran 95, Linux/Windows OS


MCNP/KENO Model Generators

Uncertainty quantification

SALOME testing


Other Efforts...

Model Generators for Uncertainty

Quantification


MCNP/KENO model

generator toolset

Modular approach

Common component data

ZED-2

SCWR

Canadian power reactors

Uncertainty Quantification: Needs

and Issues

We need to:

–Assess impact of model data uncertainties

– Integrate nuclear data uncertainties

– Integrate to overall impact on safety analyses

Current tools are:

–WIMS-AECL + MS-Excel (Model data uncertainty)

–TSUNAMI (Nuclear data uncertainty)

Issues:

–TSUNAMI ?

–Compatibility with next generation suite ?

–Computing efficiency ?


Planned Efforts in Uncertainty

Quantification

Modular SA/UQ system

–Enable use of different codes or data

–Automate model generation and execution

–Advanced input parameter sampling methods

– Integrated analyses of simulation results

…but we still need deterministic nuclear data uncertainty

analysis capability:

–Resonance self-shielding ?

–MC or 1st order perturbation theory ?

–Area of collaboration


SALOME Platform for Numerical

Simulation

• Integration platform for

numerical simulation

• Under development at

CEA and others

• Rapid prototyping for

physics integration


Structure of SALOME

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SALOME Testing Using CATHENA

and ELOCA

Used SALOME to couple two codes used in Canada

CATHENA: Canadian Algorithm for THErmal-hydraulic

Network Analysis

ELOCA: Element Loss Of Coolant Accident.

Experiment: PDF test simulating LBLOCA

Tested coupling against prior script-based setup


The PBF LBLOCA Test

Fuel conditioning, 16 hours

in reactor

Blowdown

Power increase after ~50s

Sheath T ~ 1350 K

SCRAM, then reflood


SALOME Test Results


A. Zhuchkova, “Application of the SALOME Platform to the Loose Coupling of

the CATHENA AND ELOCA Codes”, 24th Nuclear Simulation Symposium, Ottawa

Next Steps with SALOME

Tight coupling of the codes CATHENA and ELOCA

Loose coupling with neutronics code (DONJON5)

Two possible benchmarks identified to date:

–BWR Turbine Trip

–Loss of Class IV Power at Gentilly-2

Would only test DONJON/CATHENA coupling


We aim for high computing efficiency

Our codes will not be tied to a design

Our program is evolving


Summary


Contributors Dimitar Altiparmakov

Ashlea Colton

Ron Davis

Alexandra Zhuchkova

Sharon Pfeiffer

Jimmy Chow

Questions?

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