VIRTUAL ACCELERATOR CONTROL SYSTEM FOR DEVELOPMENT
STAGE OF APPLICATION-ORIENTED PROJECTS
M. Sugimoto, JAERI, Tokai, Ibaraki, Japan

1 GENERAL CONSIDERATIONS
The design approach starts with the requirement
analysis of the facility and such requirements should be
described in the conceptual design documentation. As aboundary, the generic control system of the facility is
considered to employ a multi-layered and distributed
environment as shown in Figure 1. Based on theterminology of Ref. [1] of the IFMIF conceptual design,
the top layer is the Central Control System and Common
Instrumentation (CCSCI) which provides the overall
operational and functional control capability to thefacility.
The common instrumentation covers theinterfaces of the sub-facilities and the facility
management, e.g. access control, radiation monitoring.
The second layer consists of the Instrumentation andControl Sub-Systems (ICSS) for the sub-facilities fairlyindependent to each other. The accelerator system
control is one part of the whole facility control and therelation to the other parts is also taken into account at
the same time. The further sub-layers can be added toeach ICSS for managing them as the hierarchy of thestructure. The major distinction between CCSCI andICSS is the capability of communicating to the outside1

http://efrosf.frascati.enea.it/ifmif/

Outside World

Central Control System &Common Instrumentation

Instrumentation &Control Sub-System

Sequence Synchronizer

The design of the control system needs to be started
from the beginning stage of the development for theapplication-oriented accelerator projects, to make thecommissioning period short and to achieve the highest
availability. Such a project usually consists of several
co-operating sub-facilities and the network-basedcomputer control is employed. One of the best choices
as the remote terminal is the Web-based PC because of
the accessibility and the cost-effectiveness. The conceptof the fundamental tasks is described to implement thecontrol system into the PC environment. It provides thecontrol experiments for the operators through theoperation of the virtual machines during thedevelopment phase. The experiments give the good
opportunity to receive the feedback from the machineusers and to support the planning of the repair andmaintenance procedure. The virtual components will bereplaced to the actual devices in the construction phasestep by step. An example of the experimental control
system is presented for the International Fusion
Materials Irradiation Facility1 (IFMIF).

of the facility. In the common layer the Interlock Logic
System (ILS) and the Sequence Synchronizer System(SSS) characterize the accelerator-based facility. In thefigure the two other important constructs, people(operator and user) and materials (machine, specificknowledge and environment), are not indicated. The
employed procedure is presented in Table 1 to apply theanalysis and design of the IFMIF system.

Interlock Logic System

AbstractFigure1: Generic model of accelerator control system.
Table 1: Procedure of System Analysis & Design
Step
ItemResource(1)
Requirements
Design Specifications(2)
Elements
Work Breakdown
Types
Structure(3)
Operations
Design Descriptions
Actions(4)
Scenarios
Design Documents ofContexts
Facility Operations(5)
Domains
Similar Systems
Classes(6)
Attributes"Behaviors

2 IFMIF PROJECT
2.1 Requirements Overview
The IFMIF is an accelerator-based D-Li neutron
source to simulate the neutron field environment of D-T
fusion reactor for developing the radiation-resistant andlow-activation materials. The conceptual design studyhas been carried out through 1995-1998 under the IEA
collaboration (Japan, US, EU, Russia) [1,2]. The IFMIF
design concept is based on the user’s requirements of theirradiation neutron field (Table 2) and the total current of
250-mA of deuteron beam is expected to obtain theenough irradiation volume and neutron intensity.
Table 2: Design requirements of IFMIF
Items
Requirements
Neutron flux /more than 0.4 L for a high flux
Test volume relation
region with 20 dpa/year
Neutron spectrum
first wall spectrum peakednear14 MeV as near as possibleNeutron flux gradient< 10%/cm
Machine availability
70 %Time structure
Quasi continuous operationxFunctionallyprovidesallcommand,communication, diagnostics, data acquisition, andsafety tasks for all project phases.
x Availability exceeds 99.5 %.
x Interfaces with subsystem controllers, operators,accelerator, target, test cell, and facility including
support utilities.
x Physical interfaces are mechanical, electricalconnection and shielding.
x Signal interfaces are LAN, serial/parallel bus,
and hard-wired logic lines.
x Operational requirements are:x Automatically, and/or interactively, start-up
and control operation.
x Provide timing, set point control, statesequencing, and designated functions.
x Acquire, process and display system status,
beam performance, and operating parametersagainst limits.
x Monitor and display alarms and parameter
trend.
x Provide fault detection and recovery.
x Provide fast-protect and run-permit functions.
x Provide data acquisition, formatting, storage,archiving, analysis, display presentation.
The conceptual design report indicates an example
configuration to perform the crude cost estimation. We
are sure that this estimate about hardware is not muchdifferent from the real cases at the construction,
however, the software cost is unpredictable if all above
requirements are completely satisfied.

2.2 System Analysis

Figure 2: Schematic structure of IFMIF subsystems.
The IFMIF consists of the following sub-facilities, as
shown in Figure 2.
x Accelerator facility provides two independent
125-mA, 40-MeV cw deuteron beams to thetarget.
x Target facility accepts 10-MW beam to the liquid
lithium flow with 15 m/s.
x
Test facility embodies the tiny samples packed
into 500 cm3 volume for fast neutron irradiation
tests.
x Users experimental facility handles the in-situ andthe post-irradiation experiments.
x Facility services supply the common utilities to all
sub-facilities.
The requirements for the control system are asfollows.
x Single and integrated central control system.

Firstly, the requirements are reorganized in the formof Use Case diagrams. The human factors are very
important in the plant-level operation, so that the modelneeds to include them. Many analyses for every
complex system have been already carried out and some
representative models are established in the past. The
three types of (1) real-word, (2) technology and (3)axiomatic domains2 are effective in our case. The mostcomponents and devices are involved in the real-world
domain, and technology domain covers the softwarerelated constructs. The typical and abstracted actions are
considered as the axiomatic domain. It is worth todefine these actions clearly using the domain diagramsfor the further analyses and improvements. In Figure 3,
an example of the collaboration diagram for changing
the set point data of a device.
As for the IFMIF operations, three different modes areidentified.

2

http://www.espritinc.com/1: C hange Set point: operating
staff

6: Prepare Send point

3: Request Change

UserInterface

Set point
Scheduler

Set pointD ata
7: Get Address to

2: Access
5: Reply Access
AccessC ontrol

12: Send D ata to

4: Inquire A ccess

D ata
D eliverer
8: Forward Data toSi gnal
C onditioner

Set Point
C ontroller: device 11: C ontrol D evice 10: Transform Data to Signal
controller
For devices which have readble properties
are monitored by using the other action.
For device with alarm point properties,
checks of the set point and reading areseparately carried out.

(1) In the start-up mode all subsystems aresynchronized to achieve the steady operation as
early as possible where the interface problems aremost stringent.
(2) In the steady operation mode the usual feed-backloops stabilize the system and some predictive
approach is necessary for achieving the maximum
availability.
(3) In the failure recovery and maintenance mode, theimmediate judgement of the continuation ofoperation is critical. For this purpose, a long term
operation experiences and the proper analysis isnecessary. This leads us to start the experimental
control system task from the beginning of thedevelopment stage as described below.

3 EXPERIMENTAL CONTROLThe application-oriented accelerator system should bedesigned with the highest efficiency as the top priority
like an industrial plant. From the technology side, theReliability/Availability/Maintainability & Inspectability(RAMI) is the critical issue. It is essential to accumulate
the RAMI database for each component before thesteady operation of such plant. The experimental control
system on the virtual facility is helpful to acquire theexperience about the operations and to refine the systemmodels. So it is necessary to be closely coupled with anexperimental operation database and an analysis
program to extract the RAMI information.

D ata
Receiver9: Issue C ommand

Figure 3: A collaboration diagram
prepared for the model of set pointchange.

browser based control terminal with a pseudo-GUI. An
example is shown in Figure 4, which uses DHTML and
ASP technique.

5 CONCLUSIONSThe control system of the plant-like accelerator-based
project must be considered by taking into account of theinteractions among all subsystems, human andenvironment. It is helpful to develop the models for thelater precise design and implementation. The other ways
for implementing the web browser based control areplanned.

REFERENCES[1] IFMIF CDA Team, (Ed.) M. Martone, “IFMIF
International Fusion Materials Irradiation Facility
Conceptual Design Activity Final Report”, ENEA
RT/ERG/FUS/96/11, December 1996
[2] IFMIF Team, (Ed.) A. Moeslang, " IFMIF
International Fusion Materials Irradiation Facility
Conceptual Design Evaluation Report”, FZKA
6199, December 1998.

4 PC IMPLEMENTATION
The idea described above is generic and can be
implemented in any platform, however, it is convenient
to start the development with a PC platform because ofthe richness of the available development tools. We
employ an object-oriented CASE tool to analyze therequirements and design the necessary components. The
present implementation is a trial to evaluate the web

Figure 4: Web browser based diagramtic display.