ALARA Planning and Teaching Tool Based on Virtual-Reality Technologies

ALARA Planning and Teaching Tool Based on

Virtual
-
Reality Technologies

Di Zhang
1
, X. George Xu
1
, D. Hussey
2
, S.Bushart
2

1
Nuclear Engineering and Engineering Physics, Rensselaer Polytechnic Institute, Troy, New York, USA

2
Electric Power Research Institute, Palo Alto, CA, USA

( contact Professor X. George Xu at xug2@rpi.edu )


The

VR

Dose

Simulator

soft

package

was

developed

using

Computer
-
Aided
-
Design

model

of

a

nuclear

power

plant,

augmented

Virtual
-
Reality

computer

technology,

and

advanced

software

programming
.

All

3
-
D

CAD

models

of

the

buildings,

floor

and

radiation

facility

were

imbedded

into

a

VR

authoring

environment

called

EON

that

enables

a

high

level

of

interactivity
.

The

VR

technology

implemented

by

object
-
oriented

software

design

methodology
.

Two

avatars

were

used

to

represent

a

male

and

female

worker

who

move

around

inside

the

radiation

areas

to

carry

our

various

user
-
specified

tasks
.

Dose

calculation,

a

game
-
like

scoring

system

and

interfaces

were

designed

to

stimulate

the

interactivity

between

a

user

and

the

computer
.

Fig
.
1

shows

the

flow

chart

of

the

whole

software

development

approach
.


INTRODUCTION

MATERIAL AND METHOD

In

recent

years,

the

nuclear

power

industry

has

shown

an

increasing

interest

in

using

the

latest

computer

visualization

and

virtual
-
reality

(VR)

simulation

tools

for

job

optimization,

ALARA

training,

and

security

inspection
.

Most

of

the

software

tools

developed

from

previous

studies,

however,

have

focused

on

the

technologies

involving

immersive

VR

interfaces
.

In

order

for

the

VR

technology

to

be

useful

in

the

ALARA

planning,

such

simulations

should

be

based

on

data

on

the

effective

dose

equivalent

(EDE)

required

by

the

U
.
S
.

NRC

for

radiation

protection

purposes
.

This

paper

presents

an

on
-
going

project

to

develop

a

VR

based

interactive

radiation

dose

simulation

tool

for

the

nuclear

power

plant
.

A virtual avatar, which is used to represent a worker, is controlled by the user. This avatar is required to accomplish sever
al
virtual jobs in different ‘way points”

in
the power plant. The shorter time the worker spent in finishing these jobs, the less dose he/she would receive. A score is gi
ven

to the player based on the number of
virtual jobs that have been finished and the accumulated dose the worker has received. The software provides two navigation m
eth
ods: automatic navigation and
interactive navigation to allow the player a flexibility in carrying out the jobs.


Each player needs to select an avatar at the beginning of the game (see Fig. 3 a), and then specify both the time spent on ea
ch
way point and navigation mode (Fig.
3 b). Then, the source terms and corresponding information need to be defined (Fig. 3 c). After all the parameters are provid
ed
by a player, augmented Virtual
Reality environment offers a game
-
like interactivity to allow a player to be immersed in the environment. During the whole proce
ss, the accumulated time, the
accumulated dose to an avatar, the current position of the avatar and the current dose rate are shown in real
-
time on the screen

(see Fig.3 d).

CONCLUSIONS

ACKNOWLEDGEMENT

A

Virtual
-
reality

based

training

software

package,

VR

Dose

Simulator,

has

been

demonstrated

using

3
-
D

CAD

and

VR

authoring

technologies
.

It

provides

an

interactive,

vivid,

and

easy

way

to

educate

a

worker

about

ALARA

principle

in

a

nuclear

power

plant
.

The

interface

is

user
-
friendly

and

game
-
like,

providing

the

intuitive

interface
.

With

the

incorporation

of

EDE

dose

calculations,

the

dose

to

the

worker

is

useful

for

demonstrating

compliance

with

the

radiation

protection

regulations
.


Simulation

of

the

virtual

reality

environment

A powerful VR authoring software, EON Reality, was used as the tool to implement the
virtual environment. The 3D models of both modified nuclear power plant facility and
avatars were imported into the EON. Interactive controlling effect was added for the
user to control the movement and posture of the avatars. Collision detection module
made sure that an avatar interacts realistically with the environment including things
such as always walking on a surface and not going through the wall etc.

This project was sponsored by the Electric Power Research Institute.

3D model of the nuclear power plant

Multigen

Creator

was

used

to

modify

the

surface

model

of

the

nuclear

power

plant,

which

is

shown

in

Fig
.
2
.

Considering

the

efficiency

and

compactness,

the

original

CAD

model

was

simplified
.

Collision

Detection

algorithm

was

used

to

make

sure

that

the

avatars

will

not

walk

into

walls
.

Some

facility

components

were

divided

into

multiple

pieces

to

carefully

define

the

environment
.

Two

avatars

representing

a

male

and

a

female

workers

had

“jointed

body

parts”

so

the

arms

or

legs

can

be

positions

to

simulate

different

postures
.

Graphic

interactive

interface


Visual Basic. NET (VB.NET) was used to develop the graphic interface. It is convenient for VB.NET to combine EON files into t
he
software. For dose calculation, the
communication between EON and VB.NET is critical. So in VB.NET an “instance” (i.e., an object in computer memory), which repr
ese
nts EON file, was generated.
And the information of the avatar’s coordinate could be transmitted through this instance. The coordinate is refreshed in rea
l
-
t
ime and the dose is calculated and
accumulated per second.

Dose

calculation


Two radiation source terms are provided in the software. The first one is dose map mode, while the other one is fixed radiati
on
source mode involving a gamma
source.

For dose map mode, the environment is surveyed to define exposure rate for the entire floor. The dose
-
map obtained by a radiati
on survey can be specified by
a user for a realistic nuclear power plant environment.

When a worker is moving around for a job, he/she is exposed to radiation and the total dose is accumulated.

For the fixed source mode, the source and the corresponding radioactivity is specified by the user. The gamma
-
constant of a poin
t
-
like source is used to calculate the
dose to the worker according to the distance between the avatar and the source. In both modes, the exposure is converted to e
ffe
ctive dose equivalent that have been
using the ICRP exposure
-
to dose conversion methodologies. The effective dose equivalent per kerma is energy and geometry depend
ent.

RESULTS

Fig. 1 Flow chart of the solution


Fig. 2

3D model of the nuclear power plant facility

Fig. 3 Graphic interfaces of the virtual
-
reality software package


(a) Selection of worker

(d) Virtual working environment

(c) Definition of the source

(b) Specification of parameters of virtual work