[ieee 1999 ieee nuclear science symposium. conference record. 1999 ieee nuclear science symposium...

5
A Review of the Equipment Qualification Testing Sequence Cheol So0 Goo, Bok Ryul Kim P.O.Box 1 14. Korea Institute of Nuclear Safety, Yusong, Taejon, Korea Abstract Nuclear power plant digital instrumentation and control (I&C) systems have to consider the effects of electromagnetic interference, radio frequency (EMVRFI) and power surge for reliable system operation. However, the current requirement (IEEE Std. 323) related to equipment qualification does not include the EM1 test requirement and the proper E.Q testing sequence including EMVRFI and surge withstand testing. Until now there has been no requirement regarding the proper testing sequence and no definitive technical evidence to support any particular sequence on the equipment qualification. In order to find the most conservative and reasonable testing sequence, we compared and analyzed the results of the SMMP(Sub-cooled Margin Monitoring Panel) qualification test. The SMMP consists of analog and digital modules. We measured the output voltage of the analog and digital modules of the panel before and after a heat rise and EM1 tests. The results show that output variation increases during and after the heat rise test in the analog modules but the increase is negligible in the digital modules. From our results, we conclude that the heat rise test affects the functioning of the electronic modules, although insignificantly, and the most conservative testing sequence occurs when the EMIRFI and surge withstand tests are performed after the heat rise test. I. INTRODUCTION The main purpose of environmental qualification tests for safety related equipment is to demonstrate the functional capability of relevant components or systems during their life time period including plant operation and post-accident conditions. More specifically, post accident monitoring equipment has to perform the required safety functions before, during, and after the postulated design basis events specified for that equipment. In order to verify the performance of the safety-related equipment in the most severe environmental condition, type tests on actual equipment under simulated service conditions is the preferred method. One of the key factors of type tests is the qualification test sequence which may affect the test results. Based on the IEEE std. 323, the type test should be performed in a planned sequence that meets or exceeds the expected or specified service conditions with sufficient performance margin. However, the standard does not include the EMVRFI test requirement yet. The following is the typical test sequence for the safety-related equipment qualification. 1) Inspection for damage since manufacture. 2) Base line performance testing. 3) Normal + accident radiation aging. 4) Accelerated thermal aging for normal conditions to 5) Performance testing. 6) Non-seismic mechanical vibration. 7) Seismic testing. 8) Testing under design basis accident conditions. 9) Post-testing inspection. simulate expected end of the design life. Utilities in Korea are currently replacing existing analog instrumentation and control (I&C) systems with computer- based digital I&C systems as the analog systems become obsolete. Also the utilities have installed computer-based digital I&C systems in newly constructed nuclear power plants. These computer-based digital I&C systems, which provide more operating capabilities than analog systems, operate at conditions that are more vulnerable to EMIRFI than existing analog systems. We need to ensure the reliable operation of advanced I&C system under EMVRFI and surge environmental conditions as well as the abnormal temperature and humidity conditions. Since advanced I&C equipment consisting of digital electronic modules are vulnerable and sensitive to electromagnetic interference(EMI), and power surge caused by relay and circuit breaker operation, the scope of the qualification tests should also include EMI/RFI and surge withstand testing. EM1 and power surges can result in the component's incorrect operation and damage. However, there have been no regulatory requirements for the relevant test sequence and no definitive technical evidence to support any particular sequence on the equipment qualification. In order to determine how much the heat rise test affects the functioning of the SMMP, this paper examined and compared the functional test results for the analog and digital module of the SMMP at each step of the qualification test. 11. Design description of the SMMP The equipment to be qualified is the Sub-cooled Margin Monitoring Panel (SMMP) which was developed by Woorigisool Inc. for use in Kori Nuclear Power Plant, Unit 2. Two SMMP(for Train A and Train B) will be installed in the main control room. The main function of the SMMP is to indicate the present status of the reactor core and coolant system from the estimated sub-cooled margin based on measured data. The SMMP contains the isolator, data acquisition system and associated system as shown in Table 1 Table 2 also shows the representative lists of SMMP 0-7803-5696-9/00/$10.00 (c) 2000 IEEE 1686

Upload: haduong

Post on 14-Mar-2017

215 views

Category:

Documents


3 download

TRANSCRIPT

Page 1: [IEEE 1999 IEEE Nuclear Science Symposium. Conference Record. 1999 IEEE Nuclear Science Symposium and Medical Imaging Conference - Seattle, WA, USA (24-30 Oct. 1999)] 1999 IEEE Nuclear

A Review of the Equipment Qualification Testing Sequence

Cheol So0 Goo, Bok Ryul Kim

P.O.Box 1 14. Korea Institute of Nuclear Safety, Yusong, Taejon, Korea

Abstract Nuclear power plant digital instrumentation and control

(I&C) systems have to consider the effects of electromagnetic interference, radio frequency (EMVRFI) and power surge for reliable system operation. However, the current requirement (IEEE Std. 323) related to equipment qualification does not include the EM1 test requirement and the proper E.Q testing sequence including EMVRFI and surge withstand testing.

Until now there has been no requirement regarding the proper testing sequence and no definitive technical evidence to support any particular sequence on the equipment qualification.

In order to find the most conservative and reasonable testing sequence, we compared and analyzed the results of the SMMP(Sub-cooled Margin Monitoring Panel) qualification test. The SMMP consists of analog and digital modules. We measured the output voltage of the analog and digital modules of the panel before and after a heat rise and EM1 tests. The results show that output variation increases during and after the heat rise test in the analog modules but the increase is negligible in the digital modules.

From our results, we conclude that the heat rise test affects the functioning of the electronic modules, although insignificantly, and the most conservative testing sequence occurs when the EMIRFI and surge withstand tests are performed after the heat rise test.

I. INTRODUCTION The main purpose of environmental qualification tests for

safety related equipment is to demonstrate the functional capability of relevant components or systems during their life time period including plant operation and post-accident conditions. More specifically, post accident monitoring equipment has to perform the required safety functions before, during, and after the postulated design basis events specified for that equipment. In order to verify the performance of the safety-related equipment in the most severe environmental condition, type tests on actual equipment under simulated service conditions is the preferred method.

One of the key factors of type tests is the qualification test sequence which may affect the test results. Based on the IEEE std. 323, the type test should be performed in a planned sequence that meets or exceeds the expected or specified service conditions with sufficient performance margin. However, the standard does not include the EMVRFI test requirement yet. The following is the typical test sequence for the safety-related equipment qualification. 1) Inspection for damage since manufacture.

2) Base line performance testing. 3) Normal + accident radiation aging. 4) Accelerated thermal aging for normal conditions to

5 ) Performance testing. 6) Non-seismic mechanical vibration. 7) Seismic testing. 8) Testing under design basis accident conditions. 9) Post-testing inspection.

simulate expected end of the design life.

Utilities in Korea are currently replacing existing analog instrumentation and control (I&C) systems with computer- based digital I&C systems as the analog systems become obsolete. Also the utilities have installed computer-based digital I&C systems in newly constructed nuclear power plants. These computer-based digital I&C systems, which provide more operating capabilities than analog systems, operate at conditions that are more vulnerable to EMIRFI than existing analog systems.

We need to ensure the reliable operation of advanced I&C system under EMVRFI and surge environmental conditions as well as the abnormal temperature and humidity conditions. Since advanced I&C equipment consisting of digital electronic modules are vulnerable and sensitive to electromagnetic interference(EMI), and power surge caused by relay and circuit breaker operation, the scope of the qualification tests should also include EMI/RFI and surge withstand testing. EM1 and power surges can result in the component's incorrect operation and damage.

However, there have been no regulatory requirements for the relevant test sequence and no definitive technical evidence to support any particular sequence on the equipment qualification.

In order to determine how much the heat rise test affects the functioning of the SMMP, this paper examined and compared the functional test results for the analog and digital module of the SMMP at each step of the qualification test.

11. Design description of the SMMP The equipment to be qualified is the Sub-cooled Margin

Monitoring Panel (SMMP) which was developed by Woorigisool Inc. for use in Kori Nuclear Power Plant, Unit 2. Two SMMP(for Train A and Train B) will be installed in the main control room. The main function of the SMMP is to indicate the present status of the reactor core and coolant system from the estimated sub-cooled margin based on measured data. The SMMP contains the isolator, data acquisition system and associated system as shown in Table 1 Table 2 also shows the representative lists of SMMP

0-7803-5696-9/00/$10.00 (c) 2000 IEEE 1686

Page 2: [IEEE 1999 IEEE Nuclear Science Symposium. Conference Record. 1999 IEEE Nuclear Science Symposium and Medical Imaging Conference - Seattle, WA, USA (24-30 Oct. 1999)] 1999 IEEE Nuclear

components. These modules and components are similar to those that are used generally in other digital or analog control panels in nuclear power plants. Figure (4-a) shows the simple signal flow from site sensors to an indicator or annunciator in

the main control room. All signals that go through the isolator, AIM, DIOM, CPM, AOM are transferred to the main control room indicators to support the operators.

DAS Unit

Table 1)

971 11 -009 AI module XV400A 971 11-008,09,11 3 EA Woorigisool Inc. DIO module XV220A 971 1 1-002 1 EA Woorigisool Inc. 6U 19" Sub rack 1 EA Back Plane 1 Set Woorigisool Inc. 1/0 TB 28 EA

SMMF' Units and Modules

RTD Type Isolator Dry Contact Type Isolator VME Bus Power Module

1 1 pt I X1201A 4 4pts I Digital Isolator XV8SIA 2 redundancy

Table 2) The Representative Lists of SMMP Components

Voltage Type Isolator T/C Type Isolator X 1400A Analog Isolator

I Terminal Block

I Noise Filter I

111. Qualification Tests The prescribed environmental, EMVRFI, and seismic

test programs were performed on the SMMP, which was based on the Korea Testing Laboratory (KTL) Environmental Qualification Test Plan No. G401-001 Rev. 0, Electromagnetic Interference Qualification Test Plan No. G401-010, and the Korea Institute of Machinery and Materials (KIMM) Seismic Qualification Test Plan No. QP-

S.IM 3440 Rev. B. The bases of these test plans are the general procedure IEEE std 323-1983 and IEEE std 344- 1987.

Figure 1. The SMMP qualification is performed as shown in

0-7803-5696-9/00/$10.00 (c) 2000 IEEE 1687

Page 3: [IEEE 1999 IEEE Nuclear Science Symposium. Conference Record. 1999 IEEE Nuclear Science Symposium and Medical Imaging Conference - Seattle, WA, USA (24-30 Oct. 1999)] 1999 IEEE Nuclear

Aging Analysis

Stress Analysis ................ 1 2 3 Visual Inspection

......................................................... .................. ................................................................... 470 pF, 200 V 2 VMF Bus Power Module 470 pF, 50 V 1 VMF Bus Power Module 2200 IF, 1OV 1 VMF Bus Power Module

Initial Functional Test

1

1 Burn -in Test

Environmental - Qualification Report G4-1-009

Seiamic Tal Report

Seismic Test BS1344-685.M(1)

- Electromagnetic

Figure 1) SMMP Qualification Test Sequence

EMC Test Report G4-1-010

A. Pre-aging Pre-aging is to simulate the cumulated operating profile

of the components. Generally, the pre-aging is focused on the most vulnerable components. According to the pre-aging analysis report for the SMMP(G401-008), only the aluminum electrolytic capacitors among the various components in the SMh4P were identified to have aging mechanism by heat. To find out the qualification life of the aluminum electrolytic capacitors, they were aged during the period of its qualification life at 105 "C of the maximum operating temperature of the aluminum electrolytic capacitors. The rating and quantity of the aged aluminum electrolytic capacitors are shown in the Table 3.

The pre-aging period for the aluminum electrolytic- capacitors was calculated using the Arehenius equation at the normal operating temperature 44 OC and activation energy 0.79.

(1/378- Pre-aging period = 43800h x EXP [(0.79/k) 1/3 17)]= 414h ---------- ( 1 )

* k = 8.617 x 105 eV/ O K ( Boltzmann's Constant)

Soon after pre-aging, the characteristics of the aluminum electrolytic-capacitors were checked and the result satisfied the acceptance criteria. Based on the calculation results, the aluminum electrolytic-capacitors are pre-aged during 4 14 hours at 105 O before assembling to the SMMP.

Table 3) Rating and Quantity of aged aluminum

electrolytic-capacitors

B. Burn-in Test The purpose of the bum-in test is to remove initial

failures and to verify system integrity under the condition of maximum electrical transient. The bum-in test was performed in accordance with the related test procedure and the recommended industry standard. Profile of the input voltage is given in Figure 2. The total bum-in testing period is 200 hours. According to the functional test procedure (WRI-SM-A03), important monitoring parameters such as the temperature of the modules and power supply noise conditions are measured 2 hour increments. Thermo-couples installed in the SMMP measured the temperatures of the parts to be a source generating heat. The data logging system continuously recorded the temperature of active components such as the power TR and ICs. Also the power supply noise monitoring system recorded the noise amplitude of the power lines.

48hs - llh+lWh I llh

48hs Figure 2) Input Voltage Profile for Bum-in Test

C. Heat Rise Test To verify the normal operation under the environmental

conditions in the specification, a heat rise test was performed in accordance with test procedure G401-002. The SMMP was electrically powered and monitored during the heat rise test. Deviation margin of the temperature and humidity was determined to be +2% and +5%RH, respectively. The functional capabilities were checked before and after the heat rise test under the conditions of maximum and minimum temperature. The environmental test condition during the heat rise test is indicated in Figure 3.

0-7803-5696-9/00/$10.00 (c) 2000 IEEE 1688

Page 4: [IEEE 1999 IEEE Nuclear Science Symposium. Conference Record. 1999 IEEE Nuclear Science Symposium and Medical Imaging Conference - Seattle, WA, USA (24-30 Oct. 1999)] 1999 IEEE Nuclear

Figure 3) Heat Rise Test Profile

D. Functional Test All devices shall not change state throughout the

qualification test such as heat rise, EMVRFI and power surge withstand, and seismic excitation. The following requirements were applied for the functional operability; - A I 0 function : less than 1% error of full scale. - DIO hnction : indicating the on-off conditions correctly. - Serial communication and Saved input, output signal :

less than 1% error of full scale. The SMMP was powered with 115V AC and the

functional operability was monitored electrically and/or visually before, during and after the environmental tests. Artificial input signals were provided to one (1) representative Analog-Input (AI) Module and Digital-Input- Output (DIO) Module using signal generator(s) and the following items were monitored during tests. - Output signal from one (1) representative Analog-Output

(AO) Module - Output signal from one (1) representative Digital-Input-

Output (DIO) Module - Saved input, output signals and acquisition time in the

Central Processing Module - Serial communication hnction

The signal flow block diagram and simple test signal flow and data acquisition system are shown in below Figure 4-a) and 4-b), respectively.

AIM : analog Input Module AOM : analog output Module CPM : Central Processing Module DIOM : Digital Input Output Module PSM : Power Supply Module

Figure 4-a) Block Diagram for the SMMP

0-7803-5696-9/00/$10.00 (c) 2000 IEEE 1689

Figure 4-b) Test Signal Flow Block Diagram and Data Acquisition System

IV. Comparison of Functional Test Result A. Analog Module Test

The analog module hnctional tests were performed to verify the operability of the module under normal, abnormal and accident environmental condition. The module was tested in accordance with functional test procedures at each step of qualification test program. At that time the functional operability were checked to determine whether output variation was within acceptance criteria in the functional test requirement.

The SMMP is installed in a controlled environment such as the main control room equipped with an air conditioner and humidity control system. But the S M M P has to have the capability to perform the intended function under abnormal conditions such as during an air handling unit failure in the control room. Such stresses were applied over ranges that were considerably higher than what is likely to experience in a normal nuclear power plant environment. '

It was assumed that electronic modules suffer extreme stress during type test process. In this paper, an effort was made to find out that how much such stresses affect the output function of modules. Output voltages were measured through 4 analog channels and logged on a notebook computer before, during, and after the heat rise test, respectively. Figure 5 shows the variation of the deviation between input and output analog voltage when input voltages are supplied at O%, 25%, 75%, and 100% of the rated input voltage, respectively. We note that the difference of voltage deviation depends on the time when the functional tests are performed. The bold line indicates the output voltage deviation between input and output at 60 "C and 95% RH during the heat rise test in the test chamber. Also the result shows that the output voltage deviation, which directly affects the test result, is larger than the voltage deviation before and after the heat rise test. As a result of the comparison between each test, we can infer that the extremes such as temperature and humidity are related to the hnctioning of the analog module.

B. Digital Module Test In the case of the digital module test, the on-off signal

generated by the digital signal on-off generator are given to the digital input modules of the SMMP. The on-off generator produces continuous digital signals such as on-state voltage

Page 5: [IEEE 1999 IEEE Nuclear Science Symposium. Conference Record. 1999 IEEE Nuclear Science Symposium and Medical Imaging Conference - Seattle, WA, USA (24-30 Oct. 1999)] 1999 IEEE Nuclear

signals(l4v) and off-state signals(0v). Figure 6 and 7 show the profiles for digital output voltage signals that go through digital input and output modules of the SMMP. Figure 6 shows the profiles when the digital signal generator provides on-state signals before and after the heat rise test respectively.

2 - 11.1 I--

w I---. --\

Figure 6) Comparison Output Voltages Between Before and after the Heat Rise Test When the Digital Module Input is an On-state (I 4v).

In contrast with this, the profiles of Figure 7 indicate off- state output signal voltage. From the result, it is noted that digital output voltages produced after the heat rise test have larger gaps than those before the heat rise test. Although the values are not sufficiently large to affect the functional test result of the SMMP, these graphs show a difference in the functional test result between before and after the heat rise test. Also a similar situation is found in Figure 7.

V. Conclusion The purpose of the qualification test is to demonstrate

that the SMMP maintains sufficient structural and functional integrity to withstand the prescribed environmental transient conditions(heat, seismic, EM1 etc.).

In this paper, the major concern was to find which test sequence was the most conservative and proper to confirm the integrity of the system assembled with analog and digital modules. We found that there is some difference in the output value before and after the heat rise test of the analog and digital modules, respectively. This fact means the heat rise test as a kind of environmental extreme apparently affects the functioning of an analog and digital control system like the SMMP even if it is negligible.

In view of the importance of the type test and test sequence in equipment qualification of advanced I&C systems like the SMMP, the EMLlRFI and surge withstand testing after any preconditioning and the heat rise test are the most conservative test sequence.

VI. References [I] Korea Testing Laboratory(KTL), G401-009 (1999),

"Environmental Qualification Report for the Sub-Cooled Margin Monitoring Panel for Use in Kori Nuclear Power Plant, Unit 2".

[2] KIMM, BS1344-685.M( 1) (1999), "Seismic Qualification Report for the Sub-Cooled Margin Monitoring Panel for Use in Kori Nuclear Power Plant, Unit 2".

[3] KTL, WRI-SM-A03, Rev I , "Sub-Cooled Margin Monitoring Panel Function Test Procedure'.

[4] IEEE Std-323 1983, "Qualifying Class 1E Equipment for Nuclear Power Generating Stations".

[SI IEEE Std-344 1987, "Recommended Practice for Seismic Qualification of Class 1E Equipment for Nuclear Power Generating Stations".

[6] US NRC Reg. Guide 1.89-1984, "Qualification of Class 1E Equipment for Nuclear Power Plants".

[7] KTL, G401-001 Rev. 0, "Environmental Qualification Test Plan".

[8] KTL, G401-0 10, Rev. 0, "Electromagnetic Interference Qualification Test Plan".

[9] IUMM, QP-S.IM 3440 Rev. B, "The Korea Institute of Machinety and Materials(K1MM) Seismic Qualification Test Plan".

[lo] KEPCO, "Final Safety Analysis Report, Kori Units 2, Vol 2"

0-7803-5696-9100/$10.00 (c ) 2000 IEEE 1690