Fault Tree Modeling Using CBHRA and SAF Method. Korea Atomic Energy Research Institute Hyun Gook Kang

Transcription

1 Fault Tree Modeling Using CBHRA and SAF Method Korea Atoic Energy Research Institute Hyun Goo Kang

2 Contents 1 2 Introduction Siplified Alpha Factor Method 3 Condition-based HRA Method Case Study 5 Conclusions 2

3 1. Introduction The Status of Nuclear Power Generation in Korea NPP in Operation NPP in Planning Ulchin Nuclear Power Site # 1, 2, 3,, 5, 6 Yonggwang Nuclear Power Site # 1, 2, 3,, 5, 6 Wolsong Nuclear Power Site # 1, 2, 3, Shin-Wolsong #1, 2 Kori Nuclear Power Site # 1, 2, 3, Shin-Kori # 1, 2, 3, 3

4 1. Introduction Digitalization of safety-critical functions in NPP DPPS and DESFAS of Korean Nuclear Power Plants Full digitalization in APR-100 Increased iportance of the digital I&C PSA Safety assessent (PSA of NPP is essential Ris concentration on the digital syste Functional diversities ight be useless since any functions share the sae coponents and software Redundancy in a digital syste ight be useless in the case of the CCF of the coponents Digitalized syste provides alars and indications to the operator (the failure of another redundancy

5 Plants Kori No. 1 Kori No. 1 (Upgraded in 1998 Kori No. 2,3, YG No. 1,2 YGN No. 3, Ulchin No. 3, YG No. 5,6 Wolsong No. 1,2,3, Ulchin No. 5,6 Shin Kori No. 1,2 Shin Wolsong No.1,2 Shin Kori No. 3, (APR-100 HANARO Reactor (ABB-CE (AECL PLC (AECL 1. Introduction The Status of I&C Systes in Korean NPPs Systes Reactor Trip Syste SSPS (ABB-CE ESFAS Systes SSPS (ABB-CE (ABB-CE (AECL PLC Not Applicable Protection Process Foxboro H-line Spec200 Spec200 (Foxboro 7300 Analog Analog (ABB-CE Analog (ABB-CE Analog/PDC (AECL Analog PLC PLC Analog Analog (AECL NSSS Control Foxboro H-line Spec200 Spec200 (Foxboro 7300 Analog Spec200 Spec200 (Foxboro Spec200 Spec200 (Foxboro DCC X/Y Coputers Control Spec200 (PLC Spec200 (PLC Ovation Control Coputer PCS Foxboro H-line Spec200 Spec200 (Foxboro 7300 Analog ILS (Forney PCS (Eaton Analog/Relay (AECL PCS (HFC Teleper XP (Sieens Not Applicable Turbine Control DCS DCS Mar V (GE Mar V (GE Mar V (GE Mar V (GE Mar V (GE Mar VI (GE Not Applicable Main Control Board Conventional Conventional Conventional Conventional Hybrid Hybrid Hybrid Hybrid PLC PLC Analog/PLC PLC Copact Worstation Hybrid Reference: KINS 5

6 1. Introduction Since 1999, KAERI has perfored an initiative research for the safety assessent of digitalized syste in order to eet practical needs raised in Korea Careful treatent of CCF and HRA is required Siplified alpha factor (SAF ethod Condition-based HRA (CBHRA ethod Concurrent application of CBHRA of SAF ethods SAF technique ay cause the loss of soe inforation required for CBHRA Case study will be presented 6

7 7 2. Siplified Alpha Factor Method Alpha factor (Non-staggered test Nuber of CCF events in the fault tree odel for -redundant coponent: Multiple redundancy results in an ipractically large nuber of CCF events in the fault tree odel Siplified alpha factor ethod Single CCF event represents the unavailability of syste due to the CCFs of the specific redundant coponents Assuption: the probabilities of CCF events are low enough H.G. Kang, et al., The Coon Cause Failure Probability Analysis on the Hardware of the Digital Protection Syste in Korean Standard Nuclear Power Plant, KAERI/TR-2908/2005 = = = = i i i i i C C n n 1 1 ( * ( * α = = CCF p C 2 ( t i i i C = = α α

8 2. Siplified Alpha Factor Method Merits of SAF ethod Coplexity reduction of plant or syste fault tree odel uantification result is siilar to that of detailed odel Pre-processing for SAF ethod Detailed success criteria and syste design analysis Deterination of CCF boundary which causes the unavailability of the syste Practical than the other ethods Siple fault tree than other full CCF event ethods Realistic results than other single CCF event ethods The SAF ethod ay cause the loss of soe inforation required for the post processing of cutsets 8

9 3. Condition-based HRA Huan operators are a part of the signal generation echanis Manual action plays the role of a bacup for the autoatic signal generation The HEP of anual signal generation is a conditional probability given that the autoatic signal generation fails Given condition of anual actuation Failure of processing syste Unavailability of process paraeters (sensors DISPLAY/ACTUATION DEVICE FAILURE ACTUATOR FAILURE HUMAN OPERATOR MANUAL SIGNAL FAILURE FAILURE OF SAFETY FUNCTION SIGNAL GENERATION FAILURE ALARM GENERATION FAILURE INSTRUMENTATION SENSOR FAILURE SIGNAL FAILURE AUTOMATIC SIGNAL GENERATION FAILURE SIGNAL BLOCKED BY OPERATOR 9

10 3. Condition-based HRA Conventional single event odel for huan error is not proper for this coplicated case Condition-based huan reliability assessent (CBHRA ethod was proposed to address this proble in a practical way CBHRA: A ind of post-processing of inial cutsets (MCS for treating the dependencies aong the signal generation eleents Based on the events in the corresponding MCS, proper HEP which is predeterined is assigned H.G. Kang and S.C. Jang, Application of Condition-Based HRA Method for a Manual Actuation of the Safety Features in a Nuclear Power Plant, Reliability Engineering and Systes Safety, In press,

11 3. Condition-based HRA <CBHRA Steps> (1 Conducting an investigation into possible EFCs (2 Selecting iportant EFCs (3 Developing a set of conditions in consideration of selected EFCs ( Estiating the HEP for each condition (5 Constructing a fault tree which includes one huan error (HE event for each anual action (6 Obtaining MCS by solving the fault tree (7 Post-processing of MCSs based on the inforation fro the events in a corresponding cutset 11

12 . Case Study Target: DPPS (-channel processing syste Syste success criteria: selective 2/ Application of SAF ethod Instruentation Channel a Conceptual drawing b No. of CCF channels ( CCF Coefficient Calculation C No. of syste failure CCF (F p (=F / 16 C / t c d CCF coefficient ( CCF / t Syste function failure CCF: {a,c}, {b,d}, {a,b,c}, {a,b,d}, {a,c,d}, {b,c,d}, {a,b,c,d} 12

13 . Case Study Application of CBHRA ethod Consideration of two Error Forcing Contexts (EFC - Unavailability of alars - Unavailability of indication of safety instruentation channels EFC = unavailability of inforation Criteria of availability - Alar: 2 or ore alars / alars - Indication: Case study variable Case (A: 3 or ore indications / indications Case (B: 2 or ore indications / indications Case (C: 1 or ore indications / indications 13

14 . Case Study Huan errors under two different conditions Condition 2: alar unavailable, but indication available Condition 3: alar and indication unavailable Status of the autoated Status of Syste instruentation 3 or ore channels available 2 channels available 1 channel available No channel available Noral Auto. signal: O Indication: O Alar: O <Condition 1: EOC> Auto. signal: O Indication: O/X Alar: O < Condition 1*: EOC> Auto. signal: X Indication: O/X Alar: X <Condition 2/3> Auto. signal: X Indication: X Alar: X <Condition 3> Abnoral Auto. signal: X Indication: O Alar: X <Condition 2> Auto. signal: X Indication: O/X Alar: X <Condition 2/3> Auto. signal: X Indication: O/X Alar: X <Condition 2/3> Auto. signal: X Indication: X Alar: X <Condition 3> 1

15 . Case Study Case (A: 3 or ore indications The CCF does not affect on the categorization CCF <Condition 3> Case (B: 2 or ore indications The CCFs of {a,c} and {b,d} are included in the single CCF event For the MCS which contains CCF event, two HE events : - {a,c} and {b,d} portion <Condition 2> - The other portion <Condition 3> 2 CCF Condition2 = ( C p = 2 CCF Condition3 = ( C p = 3 Case (C: 1 or ore indications {a,c}, {b,d}, {a,b,c}, {a,b,d}, {a,c,d} and {b,c,d} 3 CCF Condition 2 = ( C p = 2 CCF Condition3 = ( C p = 15

16 . Case Study Results 1.50E E-03 AFAS Failure Probability 1.0E E E E E E-03 CASE Case 1(A CASE Case 2(B CASE Case 3(C 16

17 5. Conclusion The single-event CCF odeling technique ay cause the loss of syste status inforation which is iportant in cutset analysis phase By using the sae nuber of CCF events as that of huan error conditions, the SAF ethod and the CBHRA ethod could be concurrently used without loss of accuracy The case study of the concurrent application of the SAF and the CBHRA ethod clearly deonstrates the usefulness of both ethod and the effect of EFC criteria deterination 17