Nuclear Power Plant Life Management and Longer-term Operation

Due to current social and economical framework, in last years many nuclear power plant owners started a program for the Long Term Operation (LTO)/PLIM (Plant Life Management) of their older nuclear facilities. A PLIM framework requires both a detailed review of the features of the main safety programs (Maintenance, ISI, Surveillance) and a complete integration of these safety programs into the general management system of the plant. Therefore PLiM should address safety as well economics, knowledge management as well as decision making, and provide an overall framework to keep the whole plant in a safe and economically sustainable condition. Moreover, new external factors, such as: large use of subcontractors, need for efficient management of spare parts, request for heavy plant refurbishment programs demand for updated techniques in the overall management of the plant. Therefore new organisational models have to be developed to appropriately support the PLIM framework. In recent years a network of European Research Organisations (SENUF) carried out many R&D tasks aiming at capturing the aspects of the maintenance programs where research is mostly needed and at developing suitable optimised maintenance models. Using the outcome of these initiatives, this paper aims at identifying the technical attributes of the PLIM program more directly affecting the decision for a long-term safe operation of a nuclear facility, and the issues related to its optimal implementation. A comparison of some of the available models is presented and an analysis of the potential impact on safety and non-safety programs is provided in order to support the development of optimised life management models.

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Steam Line Integrity Analyses for LTO: Enhancing Credibility With Comprehensive Measurement

Volume 3: Design and Analysis ◽

10.1115/pvp2012-78839 ◽

2012 ◽

Author(s):

Horst Rothenhöfer ◽

Andreas Manke

Keyword(s):

Power Plant ◽

Nuclear Power Plant ◽

Nuclear Power ◽

Simulation Models ◽

Proper Function ◽

Blow Down ◽

Term Operation ◽

High Level ◽

Comprehensive Measurement

The safety relevant components of nuclear power plant Neckarwestheim 1 — in service since 1976 — have been reviewed and updated for long-term operation (LTO). The actions included hardware retrofits as well as updates of analysis according to the latest state of the scientific and technical knowledge. For large piping such as the steam lines, the established pipes have been retained while the supports have been optimized. All shock absorbers (snubbers) including corresponding inertia have been eliminated resulting in a defined guidance and statically defined displacements. The integrity analyses for the optimized steam lines, including break preclusion, have been validated successfully with comprehensive measurements. The verification has delivered an extra high level of credibility, exceeding the “standard” requirements to achieve fitness for service in long-term operation. Measurement and validation, which are the main focus of this paper, range from monitoring of service loads to the static and dynamic measurements of pressure, local temperatures and displacements during initial start-up after implementation of the design modifications. The proper function of supports has been proved and the quality of the simulation models has been confirmed. Some expected and some unexpected dynamic events have been detected during blow-down tests. It was demonstrated that the amplitudes of all dynamic loads stay within limits. The validation of analyses with comprehensive measurement has been an important proof of quality and delivered the redundancy required for the integrity of a nuclear power plant in service, enhancing the high level of safety even more.

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