GENES4/ANP2003, Sep. 15-19, 2003, Kyoto, JAPAN Paper 1034

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Nuclear Power Plant C&I Design Verification by Simulation

Joachim STORM1*, Kim YU2 and D.Y. LEE 3 1Simulation Manager, STN ATLAS Elektronik, Bremen, Germany

2DCIS Manager, General Electric Nuclear Energy, San Jose, California, 94040, U.S.A., tel: 1 408 925 3895, fax 1 408 925 4885, email address: kim.yu@gene.GE.com

3Deputy Director, Nuclear Engineering Department, Taiwan Power Company, Taipei, 100, Taiwan An important part of the Advanced Boiling Water Reactor (ABWR) in the Taiwan NPP Lungmen

Units #1 and #2 is the Full Scope Simulator (FSS). The simulator was to be built according to design data and therefore, apart from the training aspect, a major part of the development is to apply a simulation based test bed for the verification, validation and improvement of plant design in the control and instrumentation (C&I) areas of unit control room equipment, operator Man Machine Interface (MMI), process computer functions and plant procedures. Furthermore the Full Scope Simulator will be used after that to allow proper training of the plant operators two years before Unit #1 fuel load. The article describes scope, methods and results of the advanced verification and validation process and highlights the advantages of test bed simulation for real power plant design and implementation. .Subsequent application of advanced simulation software tools like instrumentation and control translators, graphical model builders, process models, graphical on-line test tools and screen based or projected soft panels, allowed a team to fulfil the task of C&I verification in time before the implementation of the Distributed Control and Information System (DCIS) started. An additional area of activity was the Human Factors Engineering (HFE) for the operator MMI. Due to the fact that the ABWR design incorporates a display-based operation with most of the plant components, a dedicated verification and validation process is required by NUREG-0711. In order to support this activity an engineering test system had been installed for all the necessary HFE investigations. All detected improvements had been properly documented and used to update the plant design documentation by a defined process. The Full Scope Simulator (FSS) with hard panels and stimulated digital control and information system are in the final acceptance test process with the end customer, Taiwan Power Company.

KEYWORDS: power plant control & instrumentation, power plant simulation, power plant design verification

I. Introduction A recent project in power plant simulation is related to the Lungmen NPP project, an ABWR reactor supplied by GE Nuclear Energy for Taiwan Power Company. . STN ATLAS has the main responsibility in this simulation to model the various plant systems, couple the nucleonics, process and logic models together and integrate these base simulation with other supplies like hard panels and the Digital Control and Information System (DCIS). The main focus of the paper is the subsequent application of simulation techniques and tools as the major supporting task for the plant design verification and validation process.

The paper deals with information about the following areas:

• Reference plant • ABWR design features • Process and scope of the simulation based

design and verification program • Engineering test bed • Overall work results • Benefits and summary

II. Plant Reference

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Reference plant for this subject is the Lungmen NPP Unit #1. The site is in Taiwan north of Taipei. Unit #1 and #2 are under construction. The Taiwan Power Company (TPC) is the purchaser of the NPP project. It represents the 4th nuclear power plant project in Taiwan. The reactor is a 1370 MW ABWR from GE Nuclear Energy. GE has the responsibility for the entire reactor island including DCIS, the overall plant control and protection, control room design, simulator and project organization leadership. The responsibility includes a full scope training simulator which was awarded by GE to STN ATLAS in 12/97. The simulator shall allow proper operator training two years before fuel load based on the existing design data. Beyond this main task the simulation environment was extensively used in this project to check out and optimize C&I, display and panel design prior to implementation. The ABWR incorporates a number of design issues to increase nuclear safety which are also considered in the simulation models: • Internal Re-circulation Pumps eliminate large pipes

beneath the core and therefore avoid pump LOCAs by design

• Fine Motion Control Rods allow an improved control of the neutron flux field resulting in smaller power changes and a reduced ATWS probability. Due to a new design (rod drop and ejection) reactivity accidents could be eliminated.

• The Emergency Core Cooling (ECCS) is split into 3 independent mechanical and electrical divisions for core cooling and decay heat removal

• The Containment has severe accident mitigation features like an inert atmosphere, lower drywell special basaltic concrete as core catcher for worst case accidents with lower drywell flood capability and a containment overpressure protection.

• Redundant control and protection logic reduces failure rates

• Man-machine interface improves operator performance

The reactor island (RI) is supplied by GE who owns the design for ABWR, including all reactor safety systems. Under this package the RI- non-safety

systems and the RC&IS are supplied by subcontractors. Also the entire conventional control is under GE’s responsibility consisting of a conventional control system, screen based operator MMI and PCS called DCIS. The turbine island is provided by another company. This package includes all the BOP systems and the turbine/generator set. With this variety of suppliers, effective integration becomes critical and it was main focus of GE’s attention to use the simulation environment for design verification. III. Scope of Work The scope for the simulation based verification & validation (V&V) process can be summarized as follows: • C&I verification of all RI-safety/non-safety systems • C&I verification of all BOP- and electrical- systems • C&I verification of RC&IS • Verification of all control loops incl. Automatic

Power Regulation, RC&IS, Turbine Control • Verification of the overall plant automation • HFE investigations for 600 operator displays

according to NUREG 0711 • Panel layout and I/O-signal interface • Test of major PCS functions like SPDS, alarm

prioritization, power flow map, heat balance • Test and improvement of plant procedures IV. Simulation Based V&V Process The base for simulation based design and V&V is that the data of the basic plant design in terms of LDs and P&IDs will be processed via software tools to an engineering test bed. The engineering test bed is available as a comfortable simulation environment. Added functionality like soft panels, operator displays and an alarm and annunciator emulation as well as graphical on-line debugging tools help to test and optimize the plant design for process and C&I. The testing starts on individual system base and can be increased system by system up to the full extent of plant systems. After successful verification of the model other design aspects like panel design, I/O interface, display design, PCS functions or plant procedures are checked and optimized systematically.

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After successful V&V the results from the test bed are used to configure the real control system and can be used together with real panels and the DCIS. This establishes a straighforward design and implementation process. The main features of the engineering test bed can be summarized as follows: • Graphical software Tools for Code generation and

on-line test • Translation tools for various C&I basic design • Cross reference features for data consistency • 100 simulated plant systems

Figure 1: Simulation Based Design and Verification Process • 3-D Core kinetic and NSSS model for the reactor

vessel • Subsequent multi phase modeling for all main loop

and other steam systems applying GRIPS – CASE Tool

• C&I models based LIDO - CASE Tool • Availability of component and specific malfunctions • 300 permanent recorded parameters per session • Screen based and projected soft panels • Emulated Alarm & Annunciator System • On-line data interface to the Digital Control &

Information System (DCIS) V. Engineering Test Bed A CAD tool called GLCAD is available for creation of LDs and P&IDs. In case of the LDs the model generation is supported by high recognizing translation tools which allow the easy conversion from the LD

original format to the engineering test bed format. Due to this human errors could be widely eliminated and a unique format is available for all design contributions of the various suppliers.

Figure 2: Software Tools of Engineering Test Bed All design and initialization work had been done using this environment. For LDs the data are directly available in the drawings. For P&IDs the auxiliary tool GRIDAT supports the user with default initialization or standardized data calculation for process components. After that the indicated process for model generation takes places – all widely automated and hidden for the user for easy handling. The result is a complete simulation model, database and initial conditions which are the base for all further investigations. Also an automated generation process is available to create soft panels. It is fully based on database information about the static and dynamic elements of the panel. The tool allows a flexible generation of fully dynamic and operational soft panels of any size and panel section. The same process is available for the emulation of all kind of display systems on the market.

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Figure 3: Soft Panel and Display Generation Process After all models, soft panels and operator displays are created and initialized a suite of run-time client tools allow the easy dynamic testing and improvement of the design.

Figure 4: Engineering Test Bed Run-Time Environment The major elements of the engineering test bed suite are:

• process supervisor client

• numeric test monitor

• Trend display

• Animated LDs and P&IDs

• Soft panel

• Operator displays

All elements are supported by clients for threshold control, intervention, and initial conditions, etc. On-line animation of LDs and P&IDs within GLCAD allows the usage of the graphical environment as a comfortable debugging tool, which provides high comfort and good overview for all kind of debugging and modification work.

Figure 5: Graphical Test Tool for Logic Diagrams and P&IDs Features are, for example:

1. Line color change for binary signals 2. display of actual values for all signals 3. animation settings are saved as part of the

drawing 4. Routing via connectors

The capabilities for cross-referencing and data extraction can be outlined as follows:

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Figure 6: Cross Reference and Data Handling Capabilities While clicking on one of the connectors, pop ups are opening indicating where the signal is registered as in- or out-put. Clicking on the whished link allows an easy routing to the referenced LD. All cross reference information are generated off-line from the latest revision of LDs and is therefore the up to date information. Various queries are available to extract C&I and cross reference data. In this way it is possible to create up to date reference lists for e.g. alarms, signals to the MMI, hard I/O points or C&I parameters for various components. VI. Work Results The overall work results can be summarized as follows: • Consistent and verified C&I design prior to implementation, approx.

25.000 logic diagrams C&I setpoint database, approx. 200.000

setpoints and transmitters I/O and MMI database, approx. 100.000 data

points • Establishing a defined feedback process to optimize

the plant design • HFE investigations for approx. 600 displays

according to NUREG 0711 requirements • Test of major PCS functions, e.g. SPDS, alarm

prioritization, power flow map, heat balance • Test and improvement of plant procedures • Simulation model and various initial conditions for

initial operator training two years before fuel load VII. Summary The improvements by simulation based design and V&V can be summarized as follows: • Reduction of overall project risk (early test of the

design and chance for early improvement/corrective action prior to implementation)

• Harmonization of plant design (necessary due to various suppliers of process and C&I)

• Consistent design data base (via cross reference and data facility)

• Consistent plant procedures (simulator verified) • Early availability of training facilities (two years

before fuel load) • Overall Quality improvement (complete verified

process and C&I design prior to implementation) • Time saving during plant implementation All the a.m. issues lead to a better project performance, higher quality and finally help to save costs. This becomes possible by subsequent application of simulation technology and software tools. Furthermore such an improvement process is also related to a different attitude of the acting persons, design engineers and managers of this industry, to explore new ways for better performance and higher quality. Acknowledgment

This paper is published and presented by the kind permission of the Taiwan Power Company and is subject to the terms and conditions of the contract with General Electric Co. # 311113.64.0232 to design and deliver the Lungmen Full Scope Simulator.