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[en] First, all the preparation has been completed to meet a new code requirements, Appendix VII of ASME B and PV code Sec. XI, which will be applied to the inservice inspection of Korean Nuclear Power Plants from 1996. This code requirement was issued to augment qualification of ultrasonic examination personnel. To meet this Appendix VII requirement, a procedure of UT personnel qualification and certification were prepared, UT instructors were trained and qualified, examination questionnaire were made, flawed test pieces were designed and purchased, level II candidates were trained and qualified. Some of them were certified. Second, investigated performance were demonstration systems of nondestructive testing for advanced countries such as England, Sweden, European [ENIQ] and USA. In addition, common positions of European regulators on qualification of NDT systems for PSI/ISI were also investigated and analyzed. (author). 161 refs., 5 tabs., 17 figs
[en] For the safe operations of nuclear reactors, it is important to detect a malfunction at an early stage. Traditionally the spectral analysis performed by the periodogram has been widely used for noise of the reactor system. The results obtained from these methods may be satisfactory if a large amount of data are available. On the contrary, these methods have severe limitations on resolution, bias and variance of estimates due to the finite data length. The main purpose of the study is to develop an efficient noise analysis program applicable to reduce the error of statistics. To attain this purpose, the spectral analysis method based on the a techniques is adopted. The AR PSD is realized by using a lattice structure. Also, the Levison algorithm is used to compute efficiently the optimal parameter.
[en] In-service inspection plays an important role to assure the integrity of nuclear power plants. A number of studies and experiences such as PISC and IGSCC detection and sizing of BWR brought new requirements of performance demonstration of nondestructive testing system. However, fulfilling the requirements needs huge cost as well as a long period of preparation. Therefore, an effective approach should be pursued not only from the viewpoint of plant safety but also from the viewpoint of cost aspects. The necessities of performance demonstration are acknowledged by all related organizations in Korea, but a lot of methodologies can exist as to how it can be accomplished. This paper presents the worldwide status of performance demonstration in Europe, US, and Korea. And also a Korean perspective on the performance demonstration is discussed.
[en] The conventional nondestructive testing has been performed in those area which are susceptible to thermal stress in according to NRC 88-08,11. In addition to that, it is necessary to set up a monitoring system to prevent severe thermal stress to pipes in early stages and to develop the non-intrusive techniques to diagnose the check valve because the thermal stratification has been caused by the malfunction of the check valve in ECCS pipe. Thermal stratification monitoring system has been designed and installed at ECCS line permanently and surge line temporally in YG nuclear power plant. The data is acceptable in according to TASCS guide line. Also, the data originated from ISMS is useful for the arrangement of a special UT program and stress analysis. Applying a togetherness of acoustics and magnetics signal, it is possible to determine the parameters of the function of the check valve internals without disassembling it. This series of tests show that the accelerometers can be use d to measure and to differentiate the three types of impacts; metal to metal impacts mechanical rubs, and worn internal parts. The magnet sensors can be used to detect the opening/closing of stainless check and fluttering of disk. (author). 50 refs., 5 tabs., 28 figs
[en] Developing DB system of piping reliability including the population data and service history of damaged piping for pilot power plant. Total weld counts of shop welds, field welds and welds for measuring instruments for 14 systems of Kori unit 3. Total weld counts of shop welds, field welds and welds for measuring instruments for 12 systems of Wolsung unit 2