Development of a Nuclear
Preparedness Support System

SHIGEHIRO NUKATSUKA*1

OSAMI WATANABE*1

SEIICHI KUDOU* 1

MAKOTO YAMAGISHI*1

RYOHJI OHBA* 2

KAZUKI OKABAYASHI*2

1. Introduction

2. Configuration of MEASURESThe words 'nuclear emergency' refer to a situation inwhich unusually large amounts of radioactive materials
or radiation are released from facilities such as a nuclear
power station to the outside. In the event of a nuclear
emergency, utilities must immediately report its occurrence and subsequent events to central and local
governments, as illustrated in Fig. 1
1. They also must
conduct analyses of the accident, and must predict/assess its trajectory and how it will affect the environment
around the facility and provide the information thus acquired to the concerned organizations.
Mitsubishi Heavy Industries, Ltd. (MHI) developed
MEASURES (Multiple Radiological Emergency Assistance System for Urgent Response), which, under any
such circumstances, assists the utilities in implementing nuclear emergency response activities and supports
the plant's emergency personnel in making decisions orforming judgments. What is important in coping with anuclear emergency is to carry out a precise analysis of
the accident, to grasp the course it will follow, to makean exact prediction of its impact on the surrounding environment, and to ensure the safety of local residents.

MEASURES is equipped with the following four subsystems to assist in an effective response to a nuclearemergency. This system involves a simple configurationthat makes full use of personal computers while realizing a significant cutback in the data-handling time byassigning time-consuming operations, including 3-D Air
Flow Distribution Analysis, to parallel-processing computers. Fig. 2 shows the data processing flow that isundertaken by the subsystems.
(1) Accident Identification & Processing System (AIPS)
AIPS fulfills the following three functions: 1) dataacquisition, 2) plant status indication, and 3) identification of an initiating event. The data it processes
include plant status data (plant parameters), environmental monitoring data (environmentalparameters), and meteorological data, such as winddirections and speeds.
System Functional Flow Diagram of MEASURES
Plant parameters

Environmental parameters
Basic system

Accident Identification and Processing System (AIPS)
Nuclear Emergency
Countermeasures
Headquarters
Centralgovernment

Off-site Preparedness
Headquarters

Weather information

Off-sitecenter

Basic system
Accident Course Inference System (ACIS)
Expansion system
Accident Simulation Analysis System (ASAS)
Source term

Power station

Wide-area weather prediction data
Basic system. Identify an accident.
. Accident course.
. Predict/assess theEnvironmental Dose Projection System (EDPS)

Environmental Dose Projection.
Fig. 1 Basic concepts behind emergency management system

Environmental dose projection
Fig. 2 Process flow of subsystems under MEASURESMitsubishi Heavy Industries, Ltd.
Technical Review Vol. 43 No. 1 (Jan. 2006)*1 Nuclear Energy Systems Headquarters*2 Nagasaki Research & Development Center, Technical Headquarters1

This system displays data it has acquired in a clear
concise format, as shown in Fig. 3
3. Furthermore, AIPS
identifies an event having triggered an accident (like,for example, a piping failure) by checking the plantstatus data it has received using an Accident Diagn o s t i c Ta b l e , p r o v i d e d b a s e d o n p r e v i o u s l y
accumulated knowledge and data.
(2) Accident Course Inference System (ACIS)On the basis of the judgment on an accident-initiating event which has been provided by AIPS, ACIS
quickly infers the future trajectory of the accident
by utilizing an Event Tree Information Retrieval
technique, and assesses when the release of radioactive materials will begin and how long it will last
and at what rate. Data concerning the course of theaccident and the amount of radioactive materials released are analyzed in advance and stored in a
database to active quick response of the system inference. ACIS displays the accident progression on
an Event Tree screen.
(3) Accident Simulation Analysis System (ASAS)
Whereas ACIS uses data base ingerence in predicting the course of an accident, ASAS is designed to infer

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Wind direction (degree)oTemperature ( C)

the sequence of associated events more realistically andaccurately by utilizing a Best Estimate Analysis Program. This system is able to conduct a precise accident
analysis at real time speed, from its earlier phase.
(4) Environment Dose Projection System (EDPS)
EDPS is a system that makes speedy, precise projections concerning the important parameters in apower plant and its surrounding environments, including variations in atmospheric air flow, dispersionand changes in the concentration of radioactive materials, dose rate distribution or similar. The use ofmeteorological information such as GPV (Grid PointValue) data and also the adoption of meteorologicaldynamics and non-steady state 3-D atmospheric dispersion models enable the system to provide detailed
projections of variables of interest.
Besides, the system can also determine the kinds ofnuclides or radioactive release from the plant concerned
automatically by utilizing data from ACIS and ASAS,
or alternately, data entered by plant personnel manually. Onscreen displays available from EDPS include aWind Speed Vector Diagram, Distribution of Airborne
Concentration, Radioactivity Distribution Deposited onthe Ground, Dose Rate Distribution, and Total Dose
Rate Distribution. The system also provides animatedFig. 4
tracking of radioactive plume on the screen (Fig.
4).
Fig. 5 is a comparison between the measured values
from AMeDAS, the Meteorological Agency's regional
weather observation system and the projected values
from MEASURES.

Wind speed (m/s)

Fig. 3 Example of plant status display

2010: Analytical value: Observed value0
15:00 18:00 21:00 0:00 3:00
360
270

6:00 9:00 12:00: Analytical value: Observed value

180
90
0
15:00 18:00 21:00 0:00 3:00
1510

6:00 9:00 12:00: Analytical value: Observed value

50
15:00 18:00 21:00 0:00 3:00

6:00 9:00 12:00

Fig. 5 Comparison of the observed temperature,
wind direction, and wind

Fig. 4 Example of radioactive plume behavior animation

Mitsubishi Heavy Industries, Ltd.
Technical Review Vol. 43 No. 1 (Jan. 2006)2

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Large region
10 km (60 x 60)

Medium region
2.5 km (58 x 50)

Small region
0.83 km (74 x 68)

02 : 00-3-4-5-6-7-8
5 6 7 8 9 100.175

1.1

Fig. 6 Multiple Nesting Method which gradually narrows the region of calculation

Analytical results, which MEASURES put out for
dates and times which had been specified beforehand(variations in air temperature, wind direction and windspeed at a given observation point), show good agreement with those given by AMeDAS.
To offer the projection results precisely and promptly,
MEASURES employs means dedicated to handling timeconsuming computations, such as 3-D Air FlowDistribution Analysis. These include a Multiple Nesting
Method which, as shown in Fig. 66, gradually narrows
the region of calculation and parallel processing capability, which permits a reduction in the calculation time.

5. Conclusion
A nuclear emergency response system called MEASURES has been developed by utilizing a parallel
processing computer system. A meteorological dynamics
model is adopted in MEASURES in which a 3-D Air FlowDistribution Analysis is indispensable. Since this analysis consumes so many computation times to predict thedetails of environmental impacts precisely, it was difficult to apply this model to the prediction system, likeMEASURES, so far. To overcome this shortcoming, wehave successfully adopted a parallel processing computersystem, a Multiple Nesting Method, and so on, thus substantially reducing the analysis time. This has allowed
MEASURES to accomplish 3-D Air Flow Distribution
Analysis and the assessment/projection of environmental impacts both promptly and precisely, opening the way
for the system to find wide applications as an auxiliary
tool, not only as part of a nuclear emergency response
but in the projection of the spread of spilled harmful
gases or the damage done by varied pollutants, as well.

3. Features of MEASURESMEASURES has a system configuration which has theability to operate as an integral system working on thecoordinated functioning of subsystems, which not only
makes an environmental dose projection but also assists
with the response to a nuclear emergency or critical decision-making, while also enabling the subsystems to run
as an independent unit. MEASURES can be operated bya single person, thanks to the coordinated operation ofconstituent systems, and comes with a user interface
with excellent visibility and operability that reflects ourproprietary Main Control Board Human Machine Interface technology. To allow for system expansion,MEASURES is also integrated to facilitate the incorporation of various analysis codes.

References(1) S. TRINICASTELLI, et al., Turbulence Closure Models and Application in RAMS, Environmental Fluid Mechanics (2005) 5:169-192(2) Atmospheric Condition Prediction Method, Patent No.US6801856,
2004(3) Diffusion Status Prediction Method and Diffusion Status Prediction
System for Diffused Substance, Patent No.US6853924, 2005

4. Application to preparedness activities
MEASURES has been developed to support the implementation of nuclear emergency response activities.
Furthermore, it can be used in relation to situations otherthan nuclear accidents or for a Full-participation Exercise by Central or Local Governments, On-site
Emergency Response Drill, or Routine Training of Personnel in charge of preparedness activities so thateffective training may be carried out under assumed contingency conditions.

Shigehiro Nukatsuka

Osami Watanabe

Seiichi Kudou

Makoto Yamagishi

Ryohji Ohba

Kazuki Okabayashi

Mitsubishi Heavy Industries, Ltd.
Technical Review Vol. 43 No. 1 (Jan. 2006)

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