Graphical Expert System for Analyzing Nuclear Facility

Vulnerability

David Sulfredge

Oak Ridge National Laboratory

December 3, 2002

OAK RIDGE NATIONAL LABORATORYU.S. DEPARTMENT OF ENERGY

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Facility Vulnerability Analysis

Objectives Develop models to

predict facility response to military or terrorist weapons

Determine critical locations for enhanced protective measures

Predict collateral effects

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Nuclear Facilities are Vital Assets

Must safeguard U.S. plants About 20% of U.S.

generating capacity Considerable public

concern Need targeting tool for some

facilities Defeat energy infrastructure Defeat WMD production

Potential for serious radiological consequences

ORNL developing Visual Interactive Site Analysis Code (VISAC) to meet these needs

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• Facility Kill Probability• Facility Collateral Effects Estimates• Facility Downtime Estimates• Facility Model Editor• Event/Fault Tree Editor

VISAC Integrates the Following Functions in one Code

Provides VERY FAST “what if” Analysis for Various

Accident/Incident Scenarios

VISAC

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Core damage probability Facility kill probability

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VISAC Weapon Selection• Equipment sabotage option • Blast location

– Chosen from model editor– Chosen from viewer

• Type of blast calculation– Uniform ray trace mode– Direct ray trace mode– Air region mode

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VISAC Blast Propagation

Uniform ray tracing

Directed ray tracing

Air region method

B la s t P o in t

C ritic a lC o m p o n e n t

U n ifo rm R a ys

B la s t P o in t

C ritic a lC o m p o n e n t

B la s t P o in t

C ritic a lC o m p o n e n t

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VISAC Downtime Calculation

DT based on fault tree for facility kill Single component failure Multiple component

failure

VISAC uses a weighted DT sum

DTnet = (1/ Pkill ) Pi* DTi

Compute both serial and parallel repair times to bound answer

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VISAC Geometric Model Viewers

Image from 2-D Viewer, showing a triple orthographic projection

of a turbine building

Image from 3-D Viewer, showing an image of the entire plant

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Viewing Components by Floor Level

First Floor Second Floor

Third Floor

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Building Critical Component List by Floor

Title and highlighted critical component point to each other

VISAC BRL-CAD Model Editor

• Model editor – Create new models– Customize existing models– Move, delete objects

• Creates a BRL-CAD output file

Creates Customized Models in BRL-CAD in Minutes Instead of Days

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Construct Facility from VISAC Library Buildings

• Buildings chosen from libraries• Building positions and orientations can be varied• Screen grid available to aid building placement• Ground level and building “sinkages” can be edited

Event/Fault Tree Editor

• Tree editor – Create new tree– Customize existing trees– Delete trees– Add/Edit consequences – Change failure probability

Creates Customized Event/Fault Trees for use with Customized Geometric Models

VISAC

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VISAC Event Tree Editor• Edit targets on canvas

– Green arrow (Add or delete column)

– Green fork (Split the branch)

– Red X (Collapse the branch)

• Consequences assigned by the user

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VISAC Fault Tree Editor

• Fault trees can be modified– New gates added– New subtrees can be added– Options to copy and paste

• Add new basic events

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Example VISAC Calculation (1)

Sabotage Option Switchyard (S) 50% Steam Generator (SG1A) 50%

Overall Kill Probability 75%

Downtime Serial repair 7.33 months Parallel repair 6.67 months

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Example VISAC Calculation (2)

Most likely sequence leading to core damage highlighted in red

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Simple vs. Detailed Model VISAC Damage Maps for a Generic Two-Loop PWR

Building-level geometry

Detailed plant geometry

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Conclusions

VISAC successfully integrates geometric modeling, damage assessment, and event/fault tree consequence analysis

VISAC’s graphical editing routines can customize library models as needed

VISAC can analyze a wide variety of nuclear facility vulnerability scenarios

Code development work is continuing