Day Three (July 15, 2010)

[C-5] Condition Monitoring

C-5-1

Proactive Materials Degradation Management and Development of Condition Monitoring Technology

Tetsuo SHOJI, Yoichi TAKEDA and Jiro KUNIYA (Tohoku University)

Abstract
The predictive and preventive maintenance technologies are of increasingly importance for the long term operation (LTO) of Light Water Reactor (LWR) plants. In order for the realization of LTO, it is essential to prevent the degradation phenomena from emergence using proper maintenance programs on foreseeing the phenomena and evaluating their rates of development. In this paper, the proactive activities and the aging degradation phenomenon which were discussed in the Proactive Aging Management Group Meeting of Tohoku-Hokkaido Research Cluster of NISA Project are introduced. The necessity of the development of condition monitoring technologies is stated as well.

Keywords
Proactive materials degradation management, Condition Monitoring Technology, LWR, BWR, PWR, Plant Aging, Long Term Operation, Stress Corrosion Cracking, Flow Assisted Corrosion

C-5-2

Condition Monitoring and Damage Screening by Fiber-optic AE Sensor

Yuichi MACHIJIMA (LAZOC Inc.) and Hideaki MURAYAMA (The University of Tokyo)

Abstract
FOD (Fiber Optical Doppler) sensor, that can measure elastic wave in wide-band frequency, has been invented and developed, which utilizes Laser Doppler effect within an optical fiber. In particular, FOD sensor can detect acoustic emission (AE), which is sometimes very useful parameter to monitor in-situ damage at various equipments. Report herein is its measurement principle and its application for field use.

Keywords
Fiber-optic Sensor, Acoustic Emission(AE), Condition Monitoring, Damage Screening

C-5-3

Study on DATA transmission by 2.4GHz radio frequency in Nuclear Power Plant

Kenji TSUJI (CHUBU Electric Power Co., lnc.), Ryota MASUDA and Takuya HUKUI (Hitachi, Ltd.)

Abstract
Additional monitoring is occasionally done on suspicious equipment such as pumps, motors, valves and so on, when monitoring parameters are different from normal operation in Nuclear Power Plant. To avoid excess radiation exposure during arrangements for the additional monitoring requiring sensors installation and cables layout, wireless data transmission system is desired. ZigBee system, which uses 2.4GHz radio frequency and has repeating function, is suitable for the needs above without influencing on nuclear instrument systems or radiation monitoring systems.

Keywords
ZigBee, UWB, wireless DATA transmission, repeating function, radiation tolerance

C-5-4

Acoustic diagnosis Improves work safety and reliability of CBM

Yoshihide JIMBO, Mitsuhiro KISHIDA, Katsumi KUROYANAGI, Osamu HOTTA and Shigeru HIDA (CHUBU Plant Service Co., Ltd.)

Abstract
This paper describes study of effectiveness of applying acoustic diagnosis to CBM (Condition Based Maintenance).We usually measure data of vibration of rotating machines with accelerometer to monitor the condition of it. This work is dangerous because we put the accelerometer near the rotating shaft of the machines by hand. Therefore we tried the non-contact sensing using a microphone of acoustic diagnosis and checked the data. As a result, we got the enough data for the monitoring safely.

When rotating machines have an anomaly, usually abnormal sounds can be heard first. After a while, vibration data goes over the criteria then we maintain the machines. We suggest that we first apply acoustic diagnosis to the monitoring then change to vibration diagnosis after abnormal sounds are detected. At this time, we prepare for the maintenance of the machines. In this way, we can prepare for it much earlier than ever.

Keywords
Acoustic diagnosis, non-contact sensing, abnormal sounds, safety, reliability

C-5-5

Acoustic diagnosis improves maintenance of grease lubricated bearings

Yoshihide JIMBO, Mitsuhiro KISHIDA, Katsumi KUROYANAGI, Osamu HOTTA and Shigeru HIDA (CHUBU Plant Service Co., Ltd.)

Abstract
This paper describes effectiveness of applying acoustic diagnosis to the greasing work. When we hear abnormal sounds from grease lubricated bearings, we try greasing. As a result, usually abnormal sounds fade away. But after a while sometimes the sounds appear again. Therefore we try greasing again. The sounds fade away at the time but later appear again. We try greasing again and again but the results are the same. By this time, the temperature of the bearing has increased a lot. If the temperature increases over the criteria, the life of the bearing and grease become short. We can avoid the repetitious greasing work with acoustic diagnosis. We can decide regreasing or not by the result of the diagnosis. Moreover we can find signs of wear of bearings by the result.

Keywords
Acoustic diagnosis, Grease lubricated bearings, Temperature, Wear

C-5-6

Development of Advanced Diagnostic Technologies for Motor-operated Valves

Kotaro HEGI, Shunichi SHIMIZU, Koji HIGUMA, Koji NISHINO, Kenji OSAKI, Kazumi WATANABE (TOSHIBA CORPORATION) and Frank HAMANO (Crane Nuclear, Inc.)

Abstract
As use of condition-based maintenance is allowed in the new regulatory inspection system employed in Japan’s nuclear power plants in 2009, development of advanced diagnostic technologies for motor-operated valves (MOVs) is now required. This report discusses advanced technologies in valve-setup verification, valve performance evaluation, monitoring of valve/actuator conditions by performance diagnostic system and moreover detection of stem crack by ultrasonic diagnostic system.

Keywords
Motor-operated Valve, Diagnostics, Condition-based Maintenance, Valve Performance

C-5-7

Detection method for rubbing of sliding bearing in early stage

Takashi SAKO and Koutaro TOKUMO (Asahi Kasei Engineering Corporation)

Abstract
It is important for maintenance to detect the rubbing phenomenon of the sliding bearing in the early stage. The experiment of a slight rubbing condition conducted and the change of vibration was examined. Importantly, the fact newly found is that peaks in spectrum domain with rotational frequency period take place due to rubbing. As a result, the Cepstrum analysis was proved to be effective for the detection of rubbing in its early stage. A device, which can follow the level of quefrency, was developed based upon this idea, so that utilizing the device is highly efficient to monitor the sliding bearing condition.

Keywords
machine diagnosis, cepstrum, sliding bearing, rubbing, vibration, machine condition monitoring

C-5-8

Condition Based Maintenance of the Motor Operated Valve in Nuclear Power Plant

Keiichiro NAGAIWA, Koji TANAKA (OKANO VALVE MFG. CO.), Kenichi OYAMA, Shiro HIKITA and Atsunori KAWAMOTO (The Tokyo Electric Power Company, Inc.)

Abstract
Approximately 20,000 valves are installed in each nuclear power plant and the inspection by TBM had been adapted mainly. With the application of the new inspection system that has been implemented from January 2009, the need for adapting method conforming to CBM has been examined to optimize the conservation activities in the nuclear power plants.

The method of condition monitoring for motor-operated valve with the new diagnosis device and the effectiveness are to be addressed in the speech.

Keywords
CBM, TBM, Motor Operated Valve, Diagnosis device, On-line Maintenance, The new inspection System

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