Life extension: theory into practice

Delegates to NEI’s series of conferences on Plant Life Extension, and Plant Life Management (PLIM+PLEX), are taking part in radical and continuing change of the industry. The pace of change since the first meeting was held (in Berlin, 1991) has been extraordinary, and it is still increasing, as delegates will find this year in Madrid.

In the last two years there have been major developments in technology, in policy and in dealing with commercial realities.

ABOVE ALL: ECONOMICS?

For Rosenergoatom, as for any nuclear operator, the bottom line on life extension is “does it pay?” Nuclear power in Russia is 20% cheaper than oil-based generation, S Bugaenko will tell the conference, so there is no doubt that the company will operate its units for as long as possible.

In Madrid, for the first time at PLIM+PLEX, this aspect of life extension will be addressed explicitly, in a session covering economics and other issues. How should managers balance the book life of a plant with the day-to-day marginal cost in a competitive market? What are the insurance and staffing issues that should be considered in the long – and longer – term? Speakers including the UK’s British Energy will address the issues.

Among these questions, is that of the cost and benefit comparison of inspection, surveillance and maintenance. This question will be addressed from an economics standpoint, and also as an important practical issue in life management. Component ageing is a constant concern of operators, and questions of fatigue and design base compliance will be considered from the German and US standpoints.

One of the frequently-cited questions over life management is in the reliability of instrumentation and control equipment. EDF will discuss the results of an analysis of control systems at its plants, where the question of whether obsolescence of I&C equipment will be a practical problem was addressed directly.

ABOVE ALL: TECHNOLOGY?

Whatever the fine details of economics or policy, they all depend on the condition of the plant, and it is in defining and maintaining that technology that many new developments are taking place. For some engineers, the rate at which embrittlement of the pressure vessel develops is the most important clue to the ultimate life of the reactor. In this context the “master curve” approach to assessing vessel life may be the most important measure that can be taken: new work on the master curve and its significance will be presented this year by Tecnatom.

Speakers at PLIM+PLEX ‘99 will report on a number of other important technical challenges that have been met since 1997. They include:

• Replacing the internals at Oskarshamn 1, completed by ABB in 1998, and plans for a similar project due to begin in 2000 at Forsmark.

• The last stage of upgrading of Bohunice, carried out in a six-month project in 1998.

• Recent replacement of the moisture separator reheaters at North Anna 1, and the new designs and methods used in a second replacement at North Anna 2 this year.

• Ongoing work to replace the channels at Argentina’s unique Atucha 1 plant.

• Annealing and uprating at Loviisa in a project expected to increase the life of that unit to 45 years.

• Repairing damaged core internals at China’s Qinshan plant.

ABOVE ALL: DISCUSSION

In Berlin delegates to PLEX ‘91 speculated on whether a reactor, still meeting regulatory requirements at the end of its nominal life, really needed to be retired immediately, and they planned the long process of gaining regulatory approval for extension. Has the battle been won?

In the US – once thought to be the least likely country to accept an extended lifetime – licence renewal is taking place, and Barth Doroshuk will report to the meeting on the current situation in that country. In Switzerland, the regulator recently noted that there is “no technical reason” why older reactors should not operate for ten years longer, and newer reactors for 20 years longer, than their original 40-year life.

With the principle of PLEX established, industry members can consider how long reactors can last. Speculation of 50 or 60 years is common and will no doubt be debated in Madrid.

For those in the day-to-day business of operating reactors, the principle of life extension is just the beginning. From here on there are hard technical and commercial problems to be solved. As always, discussion, debate – even arguments – at the PLIM+PLEX meeting are the arena where those issues will be addressed.