ABOUT UI DESIGN OPTIMIZATION OF TNPS MMI

XU Jie

Author I&C Department of JNPC

Lianyungang, Jiangsu, China

ABSTRACT

Tianwan Nuclear Power Station Phase I is the first nuclear power station that adopts full digital instrumentation and control system in China. Due to the fact that there is no reference station in the complete sense for the original design, most of the design is actually new; this leads to plenty of exploration and study in terms of how the Man Machine Interface satisfies most effectively the requirements of human factors engineering. To certain extent, it affirms the utilization of digital I&C system, and proves the effectiveness of MMI, as the two units of Phase I have achieved good operation performance, economic benefits since commercial operation. So Phase II based on the successful construction and good practice of Phase I, implements the strategy of “Copy plus Improvements”. I&C System still adopts full digital I&C system; MMI is basically the same, and assimilating the experiences in aspects of design, commissioning and operation of Phase I. This essay introduces the general structure of computerized MMI in Phase I, studies and summaries the principles of display design, discourses how to realize these principles during engineering. Through aforementioned studies, this essay analyzes the display design advantages and disadvantages of Phase I, introduces some implemented measures in Phase II.

INTRODUCTION

Tianwan Nuclear Power Station Phase I processes and systems’ general designer is institute SPAEP of Russian. Full digital instrumentation and control (I&C will be used in the following contents) is used for the first time. Main I&C system is used during normal operation or events combined with relatively, independent I&C system for the reactor and fire protection and ventilation I&C system. All these I&C systems are used to monitor and control the units in all conditions. Man-

machine interface is computerized and achieved by OM690（ Operation and Monitoring System 690 ） supplied by SIEMENS. Tianwan Nuclear Power Station Phase II Nuclear Island is designed by the institute SPAEP of Russian. Phase II Conventional Island’s designer is Chinese institute. Control system is still full digital I&C system. Man-machine interface system is improved OM690 designed and supplied by CASS (Consortium of AREVA, SIMENS and SPPA). The following paper illustrates displays design process, combining principles and practices of Phase I. The paper also illustrates design improvements based on analytical results from concept design and displays’ detailed designing process.

NOMENCLATURE

NPP Nuclear Power Plant Phase I Tianwan Nuclear Power Station Phase I

(Units 1&2) Phase II Tianwan Nuclear Power Station Phase II

(Units 3&4) I&C system Instrumentation and Control (I&C) system MMI Man-Machine Interface UI User Interface HFE Human factors engineering V&V Verification and Validation

CONTENT

1. OverviewIn accordance with URD[1], each MMI system at nuclear

power stations is comprised to some degree of the following functions: Data gathering equipment which monitors equipment and

process variables;

Proceedings of the 2016 24th International Conference on Nuclear Engineering ICONE24

June 26-30, 2016, Charlotte, North Carolina

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Data communication equipment which transmits equipment and process variables between data processing equipment and plant equipment;

Plant information display and control equipment which provides alarm and display media for plant personnel to access plant processes and equipment status, and control to operate plant equipment;

Output processing equipment which provides the necessary interfaces between plant controls and plant equipment actuators.

The scope and interface for a typical integrated MMI system are shown in Figure 1.

It shows that UI is the media to transfer and exchange information between human and machine. Plant operators can intervene and check in the plant process system or control system on different levels by means of specially designed interface to enable MMI system to execute its functions.

Figure 1. Structure of man-machine interface system

Displays are one kind of UI. After adopting full-digital I&C system, except a small number of display and control in backup safety control panel/desk, a large amount of information and control is shown in different form of display.

2. Phase I’s displays Design 2.1 Establishment of Phase I’s Displays Structure

The principal users of each group of displays should be identified to convert visual hierarchy concept into actual NPP operation requirements, which will be part of design requirements definitions. There is a need for information and control as well as systems’ safety, availability and operability.

Phase I’s displays have the structure which includes overview, plant major processes, subfunctions and detailed information. It’s organized and distributed based on tasks of reactor operators, turbine operators and auxiliary system operators. The layered structure design of displays is shown in figure 2.

Figure 2 Display layered structure design

2.2 General design requirements for Phase I’s UI

The design process of the Phase I’s UI is according to the requirements of IEC964 in general. The requirements for display design used in Phase I as following: Displays should be as simple, clear and comprehensible as

possible. Where complex or highly detailed displays are necessary, good organization and structure are used.

Information shown on display shall be clearly understood in any operation conditions, and the display shall communicate the intended information to the operator without ambiguity or loss of meaning.

Standardization of displays and symbols shall be used; all items within a suite of displays which represent the same information should be similarly named.

Related items of the power plant should be organized in such a way that reflects their relationships with an appropriate degree of abstraction to avoid complication of the display.

Background colors should be neutral. It is essential to use grouping and coding techniques for enhancement of the perceptions of displayed information.

All plant conditions and most of the equipment status information of Phase I can be displayed with UI, which shows simulations, data, states, time charts and alerts of either a power plant or equipment. The displayed information is sufficient and necessary, not only gives the overall operating parameters and operating conditions of the NPP under various operating conditions, but also gives the safety status of NPP, the operating status of major equipment and the operating state of the major safety facilities. The range of the parameter settings takes into account the startup, shutdown and accident conditions; equipment state display can reflect the actual situation, such as liquid to charged state. Standard dynamic symbols are used for the valve state, the pump start or shut down upon the background color with a light gray. Standard layout is used in the measured value of the digital string.

2.3 HFE in the implementation of UI design in Phase I

It is commonly known that human factors and possible human errors play an important role in the safety and availability of the nuclear power plant which needs to achieve

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required safety and availability. HFE principle shall be obeyed and run throughout all cycle life of NPP.

We have developed a plan that defines the HFE team configuration and assure that all activities are correctly performed in Phase I. The U.S. NRC NUTEG-0711 has been used as guidance in order to ensure consistency and to address all aspects of HFE design. HFE related engineering documentation have been delivered to NNSA for review to support NPP operation license application.

HFE principle complied in the UI design, such as the set of any group displays or a display of an arbitrary element meets operators’ demand. The size of characters and symbols in readability also meets the requirements.

3. Improvement of UI for Phase II project The UI design is based on users’ demands to implement the

task correctly and quickly. It’s also based on the design instruction of NPP systems and all operation conditions of NPP. Taking into consideration the fact that the strategy of＂Copy plus Improvements＂ is adopted for Phase II project, the collection and analyzing of experience feedback from Phase I project was conducted before the UI design for Phase II project started.

3.1 Improvement of display structure Owing to the complexity of operations at nuclear power

plants, the designer of UI needs to orient the function of computerized MMI based on the quality and performance of equipment adopted, and determine the concept of how the operators conduct monitoring operation at the power plant by means of man-machine interface after completing control room function analysis and allocation, and task analysis.

Relevant materials about function design of Phase I control room has been analyzed and confirmed together with the institute and operation personnel before the design on the UI for Phase II project starts. In this way the operation configuration of power plant, function of control room, and safety, availability and operability targets of system are not changed. It is determined that no big adjustment is needed for the schematics categorization, function, hierarchical structure and organization mode, but small design improvement is made to consider hierarchical principles and operation experiences when determining display structure.

3.2 Improvement on UI design input In Phase I, the process design personnel from SPAEP

submits the input data related to the design of Main I&C system and MMI, and the personnel of SIEMENS executes the UI design. The input data of UI design includes display draft, display signal list and necessary signal logic list.

The design input of UI is summarized into the following contents at least through the investigation on the input data of UI design in Phase I for design personnel to create reasonable display: Brief description about display purpose submitted in text; Proposal about display layout submitted in sketch drawing; Necessary signals list submitted in excel form, including

signal identification (such as KKS) and signal definition; Information such as signal process logic and related time

correlation, submitted in the form of function diagram; Description about display of refresh time, description

about refresh frequency of every signal, description of test etc.

Based on a.m. analytical results, there isn’t a very important part in Phase I project, that’s the brief description about display purpose submitted in text. Therefore, it’s defined in the concept design stage of Phase II that the part of display description will be added into the input data submitted by the process design personnel including the graph, displayed signal list, necessary signal logic list and the display purpose, function and represented information Before subsequent UI design starts, the process design personnel are required to give explanation referring to the control function and corresponding display elements as for important display of control function.

From the viewpoint of implementation result, the information is not only helpful for the UI designer to understand and implement display design, but also essential for the instruction developer to correctly understand the original intention of designed monitoring means and develop various instructions.

3.3 Improvement on verification of UI design As for the UI design, the implementation condition of

general requirements of design from Phase I has been summarized as follows: Layout of information displayed in UI. Confirm that the

display layout based on the functions of NPP is reasonable, and it’s capable of transmitting the information clearly without missing anything under any condition;

Source of information displayed in UI. Simultaneous performance of display design and I&C design of corresponding function group obtains balanced design meeting actual condition;

Display interface and database used “Master plate”. The actual application in Phase I project has proved that the background color, standard symbol, interface and used schematics database etc. specified for UI design requirements are suitable and applicable.

HFE V&V have integrated with the design process, the V&V findings presented that the proposed function assignment takes the maximum advantage of the capabilities of human and machine without imposing unfavorable requirements on either of them.

Based on these analyses, the design principle and requirements haven’t been changed largely. However, it’s found during analysis that the practicality test of UI design have been passed the characteristics evaluation of design itself, but have not performed evaluation by user (as for the NPP, the user of UI is the plant operation personnel) on utilization of this design before factory acceptance.

Therefore, a multi-disciplinary owner team has been set up in the course of UI design to directly participate in the review of display draft, including I&C, commissioning and

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maintenance personnel, and operation personnel familiar with normal, abnormal and accident operation procedures. This owner’s team review the design document (including display) completed for function groups, confirm the main information and related information in one display, and especially test the unacceptable contradiction. As for subsequent factory test, this owner’s team is conduct operation verification on actual display, including the correctness of NPP displays navigation and related link, correctness of display data and rationality of information combination, to confirm if the display design conforms to the original design requirement.

For the Phase II the execution of all plant procedures will take place in a dynamic environment (mock-up or simulator) prior to the plant going into service. This effort will be lead and executed by this owner’s team.

3.4 The implementation and improvement of HFE in Display Design

The HFE has been blended in each field of design of modern nuclear power plant, so the implementation of HFE principle should be taken as a formal part during display design period and design verification period.

After applicability analysis and discrimination of the HFE principles in Phase1, from meeting the requirements of "to eliminate possible source of human failure" and "to minimize possible human failure", the principle of display design adopted in Phase 1 is reasonable and applicable for Phase Ⅱ. From the strong self-diagnosis function owed by I&C hardware device, it is able to "monitor and help correct mistakes before they influence power plant", but some aspects can be improved and implemented.

Figure 3: TDS

From the aspect of "correctly support specified task to reduce the possibility of human failure", the one method is improved to adopt the text and electronic version in Phase II, it lacks normal, abnormal and accident operation procedure of electronic display. The link will be set in UI; after clicking the procedure list will be called and then search quickly to switch digitalized procedure. And the other is provided a function

named ＂Technical Data Sheet-TDS＂(see figure 3), which is aimed at specific equipment to provide more detailed information in the form of dynamic window for operators. The information includes equipment operation parameters and technical data like specific location, acceptable scope, setting value and other specifications, due to the limitation of screen layout and MMI system, so some supportive information will be not directly shown on the screen.

CONCLUSIONS In a word, the Phase I MMI design is basically able to

provide the relatively fine, integrated, explicit and reader-friendly analysis and judgment information and also to ensure the safe, reliable and high-quality operation since commercial operation. Now with increasing NPP automation level and optimization of MMI of Phase Ⅱ display, the MMI definitely will be improved better to produce huge potential benefits because it can not only provide operator with more requirement-met and more appropriate information, but also can support the operator with information search, status understanding, correct operation and decision-making to ease the burden on the operation and judgment of the operator and to reduce human failure.

Of course, with the improvement of the computer hardware/software and the accumulation of engineering experience, there will be room for gradual upgrade and improvement.

REFERENCE

[1] Advanced Light Water Reactor Utility Requirements Document (URD), VOLUME 2 CHAPTER 10. Revision 7. [2] International Electrotechnical Commission. IEC 73: Basic and safety principles for man-machine interface, marking and identification- Coding principles for indication devices and actuators, 1996-10. [3] International Electrotechnical Commission. IEC 964: Design for control rooms of nuclear power plants, 1989-03. [4] SIEMENS Work Report. General description for the arrangement of video displays of the OM system for Tianwan NPP, 2003. [5] International Electrotechnical Commission. IEC 61772: Nuclear Power Plants - Control Rooms - Application of Visual Display Units (VDUs), 2009. [6] Consortium technical report. HFE program for control room and HMI design, 2013.

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