Izvestiya vuzov. Yadernaya Energetika

The peer-reviewed scientific and technology journal. ISSN: 0204-3327

A localization method of loose part for VVER NPPs

12/05/2019 2019 - #04 Nuclear power plants

Maksimov I.V. Perevezentsev V.V.

DOI: https://doi.org/10.26583/npe.2019.4.02

UDC: 621.039.588:534.21

As operational experience shows, it can hardly be excluded that some detached or loosened parts and even foreign objects may appear in the main circulation loop of VVER reactor plants. Naturally, the sooner such incidents are detected and evaluated, the more time will be available to eliminate or at least minimize damage to the reactor plant main equipment. The paper describes a method for localizing the impact of a detached, loosened, or foreign metallic object located in the coolant circulation circuit of a VVER reactor plant. To diagnose malfunctions of the reactor plant main equipment, it is necessary to accurately determine the place where the acoustic anomaly occurred. Therefore, if some detached, loosened or foreign objects make themselves felt, it is important to track the path of their movement along the main circulation circuit as well as their location using physical barriers.

The method is based on the representation of the surface, along which an acoustic wave propagates, as a 3D model of the RP main circulation circuit. The model has the form of a graph in which the vertices characterize the control points on the RP surface and the edges are the distances between them. The method uses information about the acoustic wave velocity and the difference in the arrival times of the leading edge at various sensors. It is shown that, when the effect is recorded by more than three sensors, along with an estimate of the impact coordinate, it becomes possible to estimate the average acoustic wave velocity. To determine the arrival time of the leading edge, the signal dispersion change detection method is used. Provided that the average size between the control points on the RP surface was 300 mm, the average localization error was about 600 mm.

The developed algorithm can be easily adapted to any VVER reactor plant. The obtained deviation values are acceptable for practical use.

References

  1. Regulatory Guide 1.133. Loose Part Detection Program for the Primary System of Light Water Cooled Reactors: tech. rep. U.S. Nuclear Regulatory Commission, 1981, 6 p.
  2. Operation and Maintenance of Nuclear Power Plants. Part 12. Loose Part Monitoring. – American Society of Mechanical Engineers (ASME), 2015. 523 p.
  3. IEC 60988 Nuclear power plants. Instrumentation important to safety. Acoustic monitoring systems for detection of loose parts: Characteristics, design criteria and operational procedures. International Electrotechnical Commission, 2009. 75 p.
  4. ISO 13379-1-2015.Condition monitoring and diagnostics of machines — Data interpretation and diagnostics techniques — Part 1: General guidelines. Moscow. Standartinform Publ., 2015, 33 p. (in Russian).
  5. Olma B. Source Location and Mass Estimation in Loose Parts Monitoring of LWR. Progress in Nuclear Energy. 1985, v. 15, pp. 583-594.
  6. Szappanos G., Kiss J.J., Por G., Kiss J.M. Analysis of Measurements made by HELPS Loose Part Detection System During Installation and operation Periods. Progress in Nuclear Energy. 1999, v. 34, no. 3, pp. 185-193.
  7. Kim Jung Soo, Hwang In Koo, Kim Jung Tak, Lyou Joon. Development of Automatic Algorithm for Localizing Loose Parts with a Steam Generator. Nuclear Engineering and Design. 2003, v. 219, no. 3, pp. 269-276.
  8. Choi Y.-C., Park J.-H., Choi K.-S. An Impact Source Localization Technique for a Nuclear Power Plant by Using Sensors Of Different Types. ISA Transactions. 2011, v. 50, no. 1, pp. 111-118.
  9. Park J.-H., Kim Y.-H. Impact Source Localization on an Elastic Plate in a Noisy Environment. Measurement Science and Technology. 2006, v. 17, no. 10, pp. 2757-2766.
  10. Park Gee Yong, Cheon Se Woo, Lee Cheol Kwon and Kwon Kee Choon. An Estimation Method for Impact Location of Loose Parts. Progress in Nuclear Energy. 2006, v. 48, no. 4, pp. 360-370.
  11. Ki H.I., Seong-In M., Soon-Woo H. ANN Based Localization of Metal Ball Impacts on Reactor Pressure Boundary Structure. Transactions of the Korean Nuclear Society. Autumn Meeting Gyeongju, Korea, October 2627. 2017. 3 p.Avilable at: https://www.kns.org/files/pre_paper/38/17A-554∗∗∗.pdf (accessed 19.02.2019).
  12. Figedy S., Oksa G. Modern Methods of Signal Processing in the Loose Part Monitoring System. Progress in Nuclear Energy. 2005, v. 46(3-4), pp. 253-267.
  13. Liska J., Kьnkel S. Localization of Loose Part Impacts on the General 3D-surface of the Nuclear Power Plant Coolant Circuit Components. Progress in Nuclear Energy. 2017, v. 99, pp. 140-146.
  14. Zheng H., Cao Y., Yang J. A Method for Estimating Impact Location of Loose Part Using HHT. Proc. of the Fourth International Symposium on Precision Mechanical Measurements. Ed. by Y. Fei, K.-C. Fan, R. Lu. SPIE, 12.2008, 6 p.
  15. Page E.S. Cumulative Sum Charts. Technometrics. 1961, v. 3, no. 1, pp. 1-9.
  16. Liu Mingzhou, Yang Jiangxin, Cao Yanpeng, Fu Weinan and Cao Yanlong. A New Method for Arrival Time Determination of Impact Signal Based on HHT and AIC. Mechanical Systems and Signal Processing. 2017, v. 86, pp. 177-187.
  17. Maksimov I.V., Pavelko V.I., Perevezencev V.V., Trykov E.L.Valid Signal Isolation Method for Loose Parts Monitoring System in the Main Circulation Circuit of VVER Reactor. Vestnik MGTU n.a. Bauman. Ser. Priborostroenie. 2018, no. 118, pp. 4-15 (in Russian).
  18. Truong C., Oudre L., Vayatis N. C. A Review of Change Point Detection Methods. 2018. Avilable at: https://arxiv.org/abs/1801.00718 (accessed Feb 19, 2019).
  19. Lavielle M. Using Penalized Contrasts for the Change-Point Problem. Signal Processing. 2005, v. 85, no. 8, pp. 1501-1510.
  20. Dijkstra E.W. A Note on Two Problems in Connexion with Graphs. Numerische Mathematik. 1959, v. 1, no. 1, pp. 269-271.

Loose Part Monitoring System (LPMS) diagnostics of NPPs impact localization acoustic wave main circulation circuit VVER reactor plant