Centurion Reactor
The term "Centurion Reactor" refers to a future class of commercial nuclear power reactors designed for, and licensed to operate for periods of time of one hundred years or longer - thus the term "centurion".  There currently are no Centurion Reactors operating in the world.  This article provides a brief overview of the Centurion Reactor concept, the technical challenges associated with achieving such longevity, and some of the business and societal issues surrounding deployment of Centurion Reactors.

Existing licenses
Commercial nuclear power plants in the United States are currently licensed, as stipulated by the Atomic Energy Act, for operating lifetimes of no more forty years.  In October, 2009, ninety-three of the 104 operating nuclear power plants in the U.S. had either been issued, had applied for, or had indicated they would apply for operating license extensions of twenty years.  Thus the majority of the U.S. commercial nuclear power fleet will operate for sixty years or possibly longer.

Demand for longevity
Weinberg noted the "trend toward nuclear reactor immortality", and advocated that "longevity" be a critical design criterion in future nuclear power plants.  More recently, Greene has elaborated on the challenges of simply extending plant lifetimes to 100 years. The limits to nuclear power plant lifetime will be determined by both technical and economic considerations, and achieving such extended lifetimes will require innovative business and financial arrangement.

Advantages of longevity
Current-generation commercial nuclear power plants (so-called "Gen III" plants) typically produce electricity at a busbar cost of 2-3 cents per kilowatt-hr after the initial capital cost of the plant is amortized. The typical amortization period for a commercial nuclear power plant is twenty years.  Thus a Centurion Reactor could theoretically produce electricity at a cost of a few cents per kilowatt-hr for eighty years or longer after the initial plant investment is recovered. The press to extend the operating lifetime of commercial power plants is driven by fundamental investment economics, land use considerations, and social justice considerations.

Investment economics
From the investment economics perspective, the allure of an 80-year profit stream to the plant owner/operator is a great attraction.  Land-use considerations are also a motivating factor.

Land use
A qualified and licensed nuclear power plant site is an extremely valuable asset due to the limited number of such sites available to energy produces.  The value of a site is directly related to the amount of energy that can be produced on that site.  Other considerations aside, the value of a specific site is directly related to the operating lifetime of the power plants on that site.

Social justice
Finally, inter-generational justice considerations motivate for maximizing the value "bequeathed" to following generations in exchange for the responsibilities associated with long-term protection and management of legacy nuclear wastes and spent nuclear fuel.

Technical challenges
The technical challenges associated with achieving Centurion Reactors lie principally in the realm of materials science.  Current Gen-III nuclear plant operating lifetimes appear to be limited primarily by long-term radiation-induced ageing phenomena in the reactor pressure vessel, primary coolant system piping, concrete containment structures, and cabling (particularly medium-voltage power cables).  In-situ replacement of all of these components and structures is problematic - the reactor pressure vessel being of particular significance in this regard.  Thus it is anticipated that substantial materials research and development will be required to open the door to this new class of nuclear power reactors.

In 2018, Rosatom began field testing a pressure vessel annealing process in the hopes of extending the longevity of this neutron embrittled and frequently fatigued part, suggesting that it could potentially extend the lifetime of a reactor 30 years.