An Evaluation of a Flowchart Type Operating Procedure for a Nuclear Power Plant in Korea

Transcription

1 1st Joint IEEE HPRCT 2007Conference 1 An Evaluation of a Flowchart Type Operating Procedure for a Nuclear Power Plant in Korea Aug. 29, 2006 Tong-il Jang I&C and Human Factors Center Korea Atomic Energy Research Institute tijang@kaeri.re.kr

2 Contents Introduction Evaluation Methods and Measures Document based review Experimental method Results Conclusions and Discussions 2

3 Periodic Safety Review(PSR) of NPP in Korea Evaluation areas : related to the safety Human factors evaluation Introduction an evaluation of a clarity of procedures with human factor principles taken into account human resources including shift management, qualification management, and training plan Human information requirement and workload a suitability evaluation of HSI(Human System Interface) 3

4 Introduction Human factors evaluation of procedures mainly evaluating operating procedures, especially EOP(Emergency Operating Procedures) a document based evaluation a human factors suitability evaluation for detailed items such as the executing steps and consisting elements experimental evaluation to verify the results of the document based evaluation and the effectiveness of EOP 4

5 The form of EOP one of the most important evaluation items effects on logical flows and connection links to another procedures two-column type : almost all plants flowchart type : some plants Two column type EOP Introduction easily comprehended : Because it performs an operation with a stream of sequence from the top of the procedure page in view of the structural property Flowchart type EOP described by logical symbols branched off by whether the conditions are satisfied or not at the decision points so that it goes back to the top of the same page or the already performed pages a possibility that it is not easy to understand the flow or the structure of the logic other related problems such as making eternal loops 5

6 Evaluation Methods and Measures An example of a procedure of SS(Shift Supervisor) 6

7 Purpose and activity of this study Introduction a document based review for a flowchart type EOP of framatome-type NPP an experimental evaluation to verify the issues which were obtained from a document based evaluation the effectiveness of EOP evaluation through a questionnaire, an interview and an observation process 7

8 Evaluation Methods and Measures The method and process of procedure evaluation in PSR Define the review criteria A preliminary evaluation based on documents A working survey - Validation of document based evaluation Issues derivation and review Present the final recommendation Define the detail criteria and requirements Collection and review the accomplishment and status data Operating Experiences Review Experts review by panel discussion Experiment evaluation - Verification of document based evaluation 8

9 Evaluation Methods and Measures The document based review evaluation scope the appropriateness of format and structure : evaluating the possibility of the workload and the confusing which may result in errors the suitability of detail items : evaluating the convenience of use and whether or not the contents of procedures are described in compliance with the human factors criteria review criteria EOP description guideline of the corresponding plant other description guidelines such as NUREG and IAEA-TECDOC development of a checklist enumeration of the evaluation items from the guidelines stated above development and use of a checklist review participants operation experts human factors experts 9

10 Evaluation Methods and Measures An example of a procedure of SS(Shift Supervisor) 10

11 Evaluation Methods and Measures An example page of a procedure of RO(Reactor Operator) 11

12 Evaluation Methods and Measures The experimental method subjects 10 subjects(2 operation group) who are working in an NPP as operators evaluator 3 observers who performed the observational evaluation 1 experimenter who led the whole process of the experiment scenarios 3 emergency operating scenarios using the flowchart type EOP 1 general operating scenario observation to verify the selected review results which were derived from a document based evaluation and which were anticipated that the importance is high in relation to the type of EOP using an evaluation form with reference to the page numbers of the procedures, contents of the review comments and the descriptions of the corresponding steps interview using a questionnaire related to the issues which seem to occur relatively easily in real operating situations and which operators are likely to experience during the training of EOP. 12

13 Evaluation Methods and Measures A check form for the result of the document based evaluation 13

14 Evaluation Methods and Measures A questionnaire form for the evaluation of procedures 14

15 Evaluation Methods and Measures Scenes of the experiment 15

16 Results The result of the document based review number of review comments about 634 review comments from 43 EOPs 16

17 The result of the document based review (cont.) Review items Primary object and secondary object Communication point Arrangement Logic diagram important review comments according to the review items Operational items and logical words Continuous monitoring items Caution and note Link to the other page or procedure Punctuation Results Review results Some cases the supervisor s and operators primary and secondary objects are different were found. In almost communication points, after some directions and requests for some measures, a process where the results of the measures reported does not exist. In the case of logical symbol, a straight line should be used to prevent some confusion of operators. In the case of YES, branching and iteration should be avoided. There were some cases in which eternal loops are produced by the wrong logical structure and sequence. In the procedure of supervisor, TO s and RO s operational items should be described in the left and right field, respectively. However, in each operator s procedure, it was switched in some cases, There was a case that the monitoring subject was uncertain. The number of the continuous monitoring items were over the number suggested in the guideline in some cases. Some cases in which the caution contains operational items were found. The contents of the caution and note were not improper and unclear logically. At the entrance points, in many cases there were not any descriptions that it is linked from which procedures. The consistency is not maintained in using of the units. 17

18 The results of the experiment A verification of the results of the document based evaluation continuous monitoring items Results it seems to be ease to be omitted because of uncertain monitoring subject. There were various cases by monitoring persons such as operators, supervisor, and senior operator. logical symbol the flow absolutely branches off in two directions without any signs such as YES or NO, so the wrong flow direction can be occurred by the operator s misunderstanding. Rx Power > P10 There were no signs such as YES or NO 18

19 The results of the experiment (cont.) A verification of the results of the document based evaluation (cont.) communication points Results after the completion of local measures, requiring some announcement from local operators to MCR operators. for the communication among the operators and the effective progression of procedure, requiring the obvious description of the communication points. primary and secondary objects when two operators of RO and TO were performing the same primary object, and in case that one of them completed ahead his secondary object, there was a case that he perform the next primary object of him, although they need close cooperation under the emergency operation situation. 19

20 The results of the experiment (cont.) A verification of the results of the document based evaluation (cont.) the indefinite end of a procedure by the wrong logical structure and sequences other comments Results a problem of readability : the letter size is so small that some operators had difficulty in reading them. the calculation and the memory loads : operators are not asked to calculate by some needs in the procedure after the execution of measure items : the return point not obvious with a description of continuous execution of proceeding step. In the procedure of RO, some asking descriptions to the TO are existing but there are no descriptions related to them in the procedure of TO. 20

21 The results of the experiment (cont.) Results results of the interview and questionnaire the procedure description method should be required for an improvement. operators depend on the procedures rather than a decision made by their experiences. in case of the conditional judgment, a possibility to be confused by the directions of the flows : there are no other methods to express the directions of the flows except for the arrows. In the case of an SGTR scenario, in diagnosis steps, a concentration level of the operators was high. Accordingly, it is required to consider this characteristic and to plan a concentrative training and education method. 21

22 Conclusion and Discussion 2007 IEEE HFPP/HPRCT Joint Conference A flowchart type of EOP which is being used in a Korean NPP was evaluated. Not having any significant problems when compared with the common twocolumn type EOP. Some improvements can be made on the partially presented problems caused by the inherent structure and format of the flowchart type EOP. no assignment who should monitor particular continuous monitoring items a degraded readability due to excessive information contents in one page unlabelled directions in the logic diagram limited communication between operators These items should be improved and reduced for an elevation of an operability of an NPP. 22

23 Thank you! 23