computational fluid dynamics for reactor design and...

Massachusetts Institute of Technology

NSENuclear Science & Engineering at MIT

science : systems : society

Computational Fluid Dynamics for Reactor Design and Safety-related Applications

Emilio [email protected]

web.mit.edu/newsoffice/2012/baglietto-better-reactors.html

STAR Japanese Conference 2013CFD for Reactor Design and Safety-related Applications

An Industrial/Research/Academic viewWearing multiple hats:

Massachusetts Institute of Technology

Assistant Professor of Nuclear Science and Engineering, Massachusetts Institute of Technology.

Deputy Lead TH Methods Focus Area, CASL – a US Department of Energy HUB.

Nuclear Industry Sector SpecialistCD-adapco.

Member of NQA-1 Software Subcommittee.

Disclaimer: the following slides are intended for general discussion. They represent the personal view of the author and not that of MIT, CASL or the ASME NQA-1 Software Subcommittee.


Nuclear Industry Competitiveness CFD for Nuclear Reactor Design Leveraging the research/academia efforts

Review - State of the art and current challenges Where and why CFD Multiscale Applications CFD as Multi-physics platform

CFD for Safety Related Applications The US-NRC example Commercial Grade Dedication of Software Experience and Challenges

Contents

Emilio Baglietto - Nuclear Science & Engineering at MIT

Background 2011- present Assistant Professor of Nuclear Science and Engineering, MIT 2006-2011 Director Nuclear Application, CD-adapco 2004-2006 Research Associate, Tokyo Institute of Technology

20122009

PBM

R

2005


Nuclear Industry Competitiveness

(since ICONE13 – 2005)


CASL: The Consortium for Advanced Simulation of Light Water ReactorsA DOE Energy Innovation Hub forModeling & Simulation of Nuclear Reactors

Task 1: Develop computer models that simulate nuclear powerplant operations, forming a “virtual reactor” for the predictivesimulation of light water reactors.Task 2: Use computer models to reduce capitaland operating costs per unit of energy, ……

6


Licensing Time / O&M Cost

7

1 Core and core components

2 Upper Internals

3 Steam Generator Internals

4 Steam Lines

5 PRZ components

6 Pumps and seals

7 Flow mixing, fatigue, shedding

8 Stratification, hydrogen accumulation


• Local T&H conditions such as pressure, velocity, cross flow magnitude can be used to address challenge problems: oGTRF oFADoDebris flow and blockage• The design TH questions under normal operating and accident conditions such as:oLower plenum flow anomalyoCore inlet flow mal-distributionoPressure dropoTurbulence mixing coefficients

input to channel codeoLift forceoCross flow between fuel

assembliesoBypass flow

• The local low information can be used as boundary conditions for micro scale models.

Model 1 Model 2

A “Typical” Multi-Scale ProblemFull-core performance is affected by localized phenomena


STAR-CCM+ Platform for MultiphysicsHigh Fidelity T-H / Neutronics / CRUD / Chemistry Modeling

Petrov, V., Kendrick, B., Walter, D., Manera, A., Impact of fluid-dynamic 3D spatial effects on the prediction of crud deposition in a 4x4 PWR sub-assembly - NURETH15, 2013


STAR-CCM+ Platform for MultiphysicsHigh Fidelity T-H / Neutronics / CRUD / Chemistry Modeling

Petrov, V., Kendrick, B., Walter, D., Manera- NURETH15, 2013


Not only Fuel Related Applications 11

Mature Applications Fuel

Pressure Drops Crud (CIPS/CILC) Vibrations (GTRF)

System and BOP Transient Mixing Hot Leg Streaming Thermal Striping SG performance Cooling Towers Interference

Fuel Cycle and Beyond Design Basis Applications Spent fuel transportation and

Storage


Multiphase CFD… better physical understanding

boiling heat transfer DNBvoid fraction


CFD for Safety-Related Design and Analysis

CFD is undoubtedly becoming a fundamental instrument in the Safety Analyst Toolbox.

CFD offers a unique opportunity for improved physical understanding

Leads to more general applicability Reduced need for empirical

calibration, which means “lower costs!”

Challenge: Provide a path for application of CFD in

Safety Analysis. Assure that the process will capture all

“critical characteristics” of the application. Make the process “Applicable”.

13


Can we apply CFD to Safety-Related Design and Analysis ?

14

Let’s try to reformulate the question: Is there a process that is robust, flexible, and cost effective

allowing application of CFD to Safety-Related Design and Analysis.

Does the process guarantee confidence in the application of CFD.

Corollary: Is the application of CFD completely

different from that of system codes.. Is it more challenging. Is it more costly.


Commercial Off-The-Shelf (COTS)

CFD is apt to rely on COTSGeneral Purpose CFD…

…reasons It has been heavily used by other industries with success. Requires very large investment for development. Inherits “experience” and verification practices. Allows leveraging a very large base of users for testing.

What are the requirements for use of COTS?

15


The fear of change … Changes from NQA-1-2008 to NQA-1a-2009 Part II, Subpart 2.7

Section 302 require application of: Part I, Requirement 7, Control of Purchased Items and Services and Part II Subpart 2.14, Quality Assurance Requirements for

Commercial Grade Items and Services

For acquisition of software that has not been previously approved under a program consistent with NQA-1 for use in its intended application.

Is it really that bad? Is it going to make it too costly to adopt COTS? Is adoption of COTS more challenging or more costly?

16


A realistic challenge Subpart 2.14 had not really been written for software, therefore

not a straightforward interpretation for an applicant. There was a need to provide a guidance for CGD of software

which would for example include.

NQA-1-2012 Non-Mandatory Appendix (NMA) Focused on dedication of Design and Analysis Computer Programs Aligns with each of the Sections of SP 2.14 and provides information

where the SP cannot be clearly interpreted as it applies to computer programs

Unique Definitions that apply to computer programs Limits application of Like-for-Like Omits Equivalency unless complete evaluation is possible

17


The process:Commercial Grade Dedication

U.S. NRC Regulatory Guide 1.28 Rev. 4, June 2010

NQA-1-2008 with NQA-1a-2009 addendum

NQA-1-2012 Non-Mandatory Appendix (NMA)

EPRI 2012 - CGD Guidance for Safety-Related Design and Analysis

18


NQA-1-2012 Non-Mandatory Appendix (NMA)CC Description Acceptance Criteria Method of VerificationHost computer operating environment

The manufacture and model number of the host assembly or computer hardware computer program is intended to reside. This critical characteristic is applicable to all computer programs.

Host computer operating environment criteria must match the purchase specification. This should include the manufacturer name and model from a supplier’s catalog. (e.g., Dell PowerEdge T110 Tower Server, IBM AIX & System, and Dell Precision T3500 Workstation, Siemens Simatic S7-400)

Verified through one or more of the following:o Inspection of receipt inspection

documentation (Method 1)o Inspection of test system operating

system identifiers. (Method 1)

Host computer operating system identifier

Vendor name, operating system version, service packs or patch identifiers that are needed for the computer to be executed. This critical characteristic is applicable to all computer programs.

Host computer operating system identifier must match the identifier in the vendor product list (e.g., Microsoft Windows 7, UNIX Operating System Version 5.1, B-5, and Yokogawa Pro-Safe-RS R2.01.00)




Software Name

The full name of the software. It should be the same identifier as used for during the procurement/acquisition process. This critical characteristic is applicable to all computer programs.

Software name must match the product name from vendor catalog. (e.g., CFAST, Wolfram Mathematica 8, Monte Carlo N-Particle Transport Code System (MCNP5), Emerson valve Link, and Organic Concatenater)




Software Version Identifier

The complete version identifier including any patches. This critical characteristic is applicable to all computer programs.

Software version identifier must match the product identifier from the vendor catalog that includes software name-major functional version, minor functional version. corrective revision (e.g., CFAST-05.00.01, Hotspot-02.07.01, Emerson valve Link-02.04-13, and Organic Concatenater-3.1b)





How does it apply to CFD4 Categories of Critical Characteristics Identification i.e., version, build date, release name, or part or catalog number

Physical physical media (e.g., CD, tapes, downloads, or remote access)

Performance/Functional required functionality of the computer program to perform its safety

function and the accuracy of its results Dependability (unique to computer programs) Evaluation to develop judgment regarding built-in quality Includes attributes related to the supplier’s software development

process such as review of the computer program’s lifecycle processes and output documentation, review of configuration management activities, testing and V&V activities, and other activities.


Performance/Functional CCs

Item characteristics

Critical Characteristics for Performance/Functional

Item characteristics

Critical Characteristics for Performance/Functional

COTS CFD


Striking a good balance

It is fundamental to balance the application of the Process and the Analysis Methodology.

Failures in applying CFD to Safety-Related Design and Analysis are related to incorrect use of the process.

Method

Failures are not unique to CFD, but it is a “common” failure mode.

Adoption of CFD for Safety-Related Design and Analysis requires the active contribution from CFD experts*.

Let’s look at 2 representative examples of Incorrect CGD of CFD Software for Safety-Related Design and Analysis


“Faith in the box” failure Solving Navier-Stokes is just like solving another problem (e.g.

structural analysis).

Very personal view: the CGD guidelines are a very natural approach to support CFD.

The process will quickly become lighter and faster as the number of CFD applications grows.

V&V Support Routine


A more challenging example…

The Flux Capacitor would most likely be considered a safety grade component.

SAR would need to include predictions of HTCs during all normal and off-normal operational conditions.

CFD provides an excellent method to support Safety-Related Design and Analysis.

Nuclear Powered DeLorean DMC-12

CFD

model of

Flux Capacitor


Example of SAR

Is this sufficient / adequate ?

Validation of CFD applicability based on separate effects analysis: Flow in a Y – junction

2D Cavity Buoyant flow

Air tests for single tube from literature, HTC data available at representative Re.

Literature recommends K-w SST Model for better HTC prediction due to “superior performance in modeling the near wall region”.


Validation example

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

0.01 0.1 1 10

Nu

/Nu

0

Bo

Data of Easby (1978)

Data of Parlatan et al (1996)

CFD results are well within the uncertainty bounds. Good prediction of Buoyancy effect. K-w SST results are conservative. Sensitivity shows acceptable influence of turbulence models.

K-e modelK-w SST model

Is this sufficient / adequate ?


0.3

0.5

0.7

0.9

1.1

1.3

1.5

0.01 0.1 1 10

Nu

/Nu

0

Bo

k-omega-SST Model (ACME CFD)

k-omega-SST Model (BCME CFD)

DBA conditions, flow reversal

CFD Model predict 2x higher HTCs at Bo=0.2 Did CFD fail? Was the Process Correct?

This is not looking good


CFD Results – failure mode analysis

Low-Re k-e K-w SST

Velo

city

Turb

ulen

t Kin

etic

Ene

rgy


How did we fail? Performance/Functional required functionality of the computer program to perform its safety

function and the accuracy of its results … Must account for effect of buoyancy on heat transfer. ..

Missing a fundamental critical characteristic.

The model equations do not have a buoyancy term for TKE and dissipation.

CFD – Code Manual

Gb ??


Conclusions

Yes, it can be done and it has been done. The CGD process provides a robust and flexible framework

to adopt CFD for Safety Analysis. The CGD process requires rigorous assessment of the

“functionality of the computer program to perform its safety function and the accuracy of its results”.

For CFD this means understanding of the physical models and VUQ of the models on the intended application.

The CGD formalizes a process that is applied to all Safety-Related Design and Analysis.

Can we apply CFD to Safety-Related Design and Analysis ?

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