This special issue of Nuclear Technology is devoted to evaluation of a new fuel design for the pressurized water reactor (PWR). It has a potential to increase the safety margin and power density of this most widely deployed type of power reactor. The idea is simple and involves increasing the surface-to-volume ratio of the fuel by adopting an annular geometry with internal and external cooling of the fuel. Undertaken with support from the initial phase of the Nuclear Energy Research Initiative (NERI) of the U.S. Department of Energy, the idea has undergone a thorough examination by researchers from Massachusetts Institute of Technology with industrial support from Westinghouse, Gamma Engineering, AREVA, and Atomic Energy of Canada Limited. This dedicated issue provides an inclusive technical review and economic assessment of the project in nine technical papers from the project team members. Hence, conclusions of this research have been documented in one archival location, which we hope will be of value to the technical community.

The United States led the world in the development of the PWR, and this technology won over many countries, including some that began the nuclear energy era with focus on other concepts. Today the world appears ready for another phase of expansion in nuclear energy, which likely will be based in large part on PWR technology. While many aspects of the primary coolant system and even the containment design have been revamped in the recently developed Generation III reactors, the fuel has been left in its original form. Yet, it is the fuel performance that controls the power that can be extracted from the core and the response to transients, in other words, the economics and safety of the power plant. Therefore, the PWR fuel deserves a much more thorough examination for innovations that enable improved performance of nuclear energy in the next few decades.

The annular fuel development for PWRs is an example of near-term research and development effort that has essentially been abandoned by both the U.S. government and industry. The U.S. government had decided that the PWR technology was mature and should not be given more development funding; the industry had decided that to change the fuel implies starting a new learning curve to ensure high degree of reliability, and until very recently had no intention of covering the cost of going after such fundamental changes in nuclear technology. Well, the market for nuclear has now expanded, and the investment in changes in the fuel that can bring about increased safety or economics can no longer be cast aside because of limited potential return on investment. Hopefully, fuel vendors and users will benefit from the extensive work documented in this issue.