{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,2]],"date-time":"2026-09-02T05:30:56Z","timestamp":1788327056646,"version":"build-2803163510"},"reference-count":12,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2026,1,29]],"date-time":"2026-01-29T00:00:00Z","timestamp":1769644800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"NPP Kr\u0161ko maintenance program"},{"name":"NPP Kr\u0161ko"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Ensuring the structural integrity of high-energy piping systems is a critical requirement for the safe operation of nuclear power plants. This paper presents the design, implementation, and three-year operational validation of a three-dimensional displacement monitoring system installed on the steam generator blowdown pipeline of the Kr\u0161ko Nuclear Power Plant. The system was developed to verify that the plant\u2019s operating procedures will not induce excessive dynamic displacements during operation. The measurement system configuration utilizes three non-collinear inductive displacement transducers from Hottinger Baldwin Messtechnik (HBM WA\/500 mm-L), mounted via miniature universal joints to a reference plate and to a defined observation point on the pipeline. This arrangement enables the real-time monitoring of X, Y, and Z displacements within a spherical measurement volume of approximately 0.5 m. Data are continuously acquired via an HBM QuantumX MX840B amplifier and processed using CATMAN Easy-AP software through a fiber-optic communication link between the containment and control areas. The system has operated continuously for more than three years under elevated temperature and radiation conditions, confirming its reliability and robustness. The correlation of the measured displacements with process parameters such as the flow rate, pressure, and temperature provides valuable insight into transient events and contributes to predictive maintenance strategies. The presented methodology demonstrates a practical and radiation-tolerant approach for the continuous structural monitoring of nuclear plant piping systems.<\/jats:p>","DOI":"10.3390\/s26030895","type":"journal-article","created":{"date-parts":[[2026,1,29]],"date-time":"2026-01-29T14:52:36Z","timestamp":1769698356000},"page":"895","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Development and Long\u2013Term Operation of a Three-Dimensional Displacement Monitoring System for Nuclear Power Plant Piping"],"prefix":"10.3390","volume":"26","author":[{"ORCID":"https:\/\/orcid.org\/0009-0007-8609-6478","authenticated-orcid":false,"given":"Damjan","family":"Lapuh","sequence":"first","affiliation":[{"name":"Nuclear Power Plant Kr\u0161ko, Vrbina 12, SI-8270 Kr\u0161ko, Slovenia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0786-9791","authenticated-orcid":false,"given":"Peter","family":"Virti\u010d","sequence":"additional","affiliation":[{"name":"Faculty of Energy Technology, University of Maribor, Ho\u010devarjev Trg 1, SI-8270 Kr\u0161ko, Slovenia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4874-1126","authenticated-orcid":false,"given":"Andrej","family":"\u0160trukelj","sequence":"additional","affiliation":[{"name":"Faculty of Civil Engineering, Transportation Engineering and Architecture, University of Maribor, Smetanova 17, SI-2000 Maribor, Slovenia"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,1,29]]},"reference":[{"key":"ref_1","unstructured":"Reber\u0161ek, J. (2025). Sistem Kalu\u017eenja Uparjalnikov (BD) SOP-3.2.310, Kr\u0161ko Nuclear Power Plant (NEK). internal document."},{"key":"ref_2","unstructured":"Nayyar, M.L. (2017). Piping Handbook, McGraw-Hill Education. [8th ed.]."},{"key":"ref_3","unstructured":"Zak\u0161ek, B. (2024). Postopek Pregleda Cevnih Obes PMM-4.011; internal document, Kr\u0161ko Nuclear Power Plant (NEK)."},{"key":"ref_4","first-page":"538","article-title":"An overview of stress analysis of high-energy pipeline systems used in thermal power plants","volume":"3","author":"Koorse","year":"2014","journal-title":"Int. J. Renew. Energy Technol."},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Yang, L., Li, S., and Hou, J. (2025). A comprehensive review of flow-induced vibration and acoustic resonance phenomena in industrial pipe systems. Machines, 13.","DOI":"10.3390\/machines13090766"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"101","DOI":"10.1002\/prs.12517","article-title":"Avoiding water hammer and other hydraulic transients","volume":"43","author":"Britton","year":"2024","journal-title":"Process Saf. Prog."},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"Chang, S. (2021). Seismic performance of piping systems of isolated nuclear power plants. Energies, 14.","DOI":"10.3390\/en14134028"},{"key":"ref_8","unstructured":"Abdul Ghaffar, M.H., Lee, D.S., Husin, S., and Wan Ismail, W.Y. (2014, January 27\u201330). High-temperature steam pipe real-time displacement monitoring system of gas-fired power plant. Proceedings of the Conference of the Electric Power Supply Industry, Jeju Island, Republic of Korea. Code C.11."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"2164","DOI":"10.4028\/www.scientific.net\/KEM.297-300.2164","article-title":"Real-time displacement monitoring system for high temperature steam pipe of fossil power plant","volume":"297\u2013300","author":"Hyun","year":"2005","journal-title":"Key Eng. Mater."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"62","DOI":"10.11648\/j.ijtet.20170304.13","article-title":"Linear variable differential transducer (LVDT) and its applications in civil engineering","volume":"3","author":"Joshi","year":"2017","journal-title":"Int. J. Transp. Eng. Technol."},{"key":"ref_11","unstructured":"Leino, J., Kokko, V., and Hyv\u00e4rinen, J. (2021). Mapping of Condition Monitoring Systems in Olkiluoto Nuclear Power Plants, Energiforsk. Available online: https:\/\/energiforsk.se\/media\/29874\/mapping-of-condition-monitoring-systems-in-olkiluoto-nuclear-powerplants-energiforskrapport-2021-785.pdf."},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Rybarczyk, D. (2021). Application of the MEMS accelerometer as the position sensor in linear electrohydraulic drive. Sensors, 21.","DOI":"10.3390\/s21041479"}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/26\/3\/895\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,1,29]],"date-time":"2026-01-29T14:54:19Z","timestamp":1769698459000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/26\/3\/895"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,1,29]]},"references-count":12,"journal-issue":{"issue":"3","published-online":{"date-parts":[[2026,2]]}},"alternative-id":["s26030895"],"URL":"https:\/\/doi.org\/10.3390\/s26030895","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,1,29]]}}}