Day Three (July 15, 2010)

[C-4] Online maintenance

C-4-1

Online Maintenance

Koji OKAMOTO (The University of Tokyo)

Abstract
Online maintenance is a option of advanced maintenance system started on 2009. With the risk for hardware and software, the online maintenance for important system will be considered to be better than that of offline maintenance. The key issue is the improvement of software system including the human factor and organizing systems on maintenance.

Keywords
Online maintenance, risk management

C-4-2

Obtain Public Trust through Safety and Stable Operation of Nuclear Power Plants by Conducting the Online Maintenance

Tadashi NARABAYASHI (Hokkaido University)

Abstract
It is very important to enhance safety and stable operation of nuclear power plants through maintenance　technologies and human activities. Recent years, the capacity factor of Japanese plant is very low compared　with the European and American plants. During a decades, the capacity factor of Japanese plants getting worth　and worth. The old type of maintenance during annual inspection made to slowdown the development of new　type maintenance, such as on line monitoring and maintenance. Therefore we should develop a lot of　maintenance technologies and conduct the daily maintenance activities and obtain the public trust.

Keywords
nuclear power plants, capacity factor, annual inspection, on line monitoring, on line maintenance

C-4-3

Risk and Maintenance: Application to Nuclear Power Plants in Foreign Countries

Kunio ITO (JAPAN NUS CO., Ltd.)

Abstract
The application status of risk information in the area of operation and maintenance at US and European nuclear power plants has been reviewed. In the US, risk-informed activities have become ingrained in nuclear power plant operation and maintenance over the past 15 years, providing both safety and operational benefits. In addition to the many US plants, Risk-Informed inservice inspection (RI-ISI) and On-Line Maintenance have been utilized in many of the European nuclear power plants, especially at the plants whose safety design has additional redundancy.

Keywords
Risk-Informed, On-Line Maintenance, Risk Management Action, Technical Specifications, Allowed Outage Time, PRA, ISI

C-4-4

Application of risk based insights to US-APWR Technical Specifications

Katsuya KUROIWA, Hiromichi TAKAHASHI and Etsuro SAJI (Mitsubishi Heavy Industries, LTD.)

Abstract
A lot of Nuclear Power Plants in the US change Completion Time and Surveillance Frequency in the Technical Specifications with risk based insights. Above all, Risk-Managed Technical Specifications (RMTS) which can be approved to change flexibly the Completion Time with PSA results and Surveillance Frequency Control Program (SFCP) which can be approved to change flexibly the Surveillance Frequency with PSA results are revolutionary Risk-informed Management methods.

MHI have applied RMTS and SFCP methods to the Technical Specifications of US-APWR.

Keywords
Technical Specifications, RMTS, SFCP, Completion Time, Surveillance Frequency, US-APWR

C-4-5

Risk Informed Maintenance Activity

Koichi MIYATA (The Tokyo Electric Power Company, Inc.)

Abstract
In recent years, risk informed activities are being investigated as scientifically rational measures. Some Risk informed activities using Core Damage Frequency (CDF) have been already employed. Examples are extraction of accident management strategies, risk informed maintenance importance and such.

This paper describes risk information such as CDF, risk profile, risk importance of equipments’ contribution to risk, gained from Probabilistic Analysis (PSA) .

Furthermore, risk informed activities conducted and/or considered are also introduced. The examples are investigation of accident management strategies, on-line maintenance and risk informed In Service Inspection (ISI).

In the end, open issues for further employment of risk information in the NPP activities are summarized. Technical quality of PSA methodology is one of these issues and it should be continuously addressed, however, the risk information as it is still useful for better activities in NPP.

Keywords
risk, PSA, CDF, on-line maintenance

C-4-6

A Study for the Practical Methods and Evaluations for the On-Line Maintenance

Takahiro OGAMI (The Kansai Electric Power Co., INC. )

Abstract
For planning and enforcing the On Line Maintenance (OLM) in the near future, we should take care of keep reasonable balance between the degree of risk increase and the task volume equalization. In this paper, the current status of studying for the OLM introducing on Japanese utilities is described. The planning approach of OLM is examined on the assumption that planned OLM can be carried out. The practical methods and evaluations for the OLM are described, and the trial evaluation for this method is also described.

Keywords
On Line Maintenance, Planning Approach, Risk Increase, Task Volume Equalization

 

Fig. 18 A keynote presentation by Prof. Okamoto on [C-4] "Online maintenance"

Reference:
Proceedings of JSM 7th Annual Conference, p.455-p.473, Omaezaki, July 2010 (in Japanese).

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