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The first generation of nuclear reactor prototypes were constructed in the 1950s and 60s and culminated in the construction of the first series of civil nuclear power reactors. The construction of the second generation of reactors started at the beginning of the 1970s and marked the widespread appearance of Light Water Reactors (LWR), either Pressurized Water Reactors (PWR) or Boiling Water Reac... more

One of the fundamental goals for Generation IV nuclear energy systems is that they will have a clear life-cycle cost advantage over other energy sources. However, since Generation IV reactors are still at an early stage of development and will not be deployed commercially for at least two to three decades, it is difficult to quantify these cost benefits. In particular, Generation IV systems char... more

Since they have been designed to operate in a thermal (less energetic) neutron spectrum, current Gen-II and Gen-III Light-Water Reactors (LWRs) can extract fission energy from only a small fraction of the uranium in the fuel (effectively only the "fissile" U-235 component, which makes up less than 1% of natural uranium). Under such conditions, known and easily accessible uranium reserves are cap... more

A fast reactor operates in a more energetic neutron spectrum, and is able, via nuclear transformations within the fuel, to "breed" fissile plutonium (Pu-239) from fertile uranium (U-238), which can then be recycled in fresh fuel. In this way, the energetic potential of U-238, representing more than 99% of the original natural uranium, can also be exploited.

Gen IV fast reactor designs will rep... more

Recycling all the minor actinides back into fresh fuel enables them to be "burnt" in the reactor and transformed into so-called fission products. These fission products are separated out from the fuel in the reprocessing plant and constitute the "ultimate" waste from the process. This waste must be managed and ultimately disposed of in line with accepted and approved practice. The radioactivity ... more

Along with the physical and administrative monitoring, control and security measures currently in place, careful selection of the fuel composition and reprocessing techniques may further increase the proliferation resistance of the Gen IV nuclear fuel cycle. Making nuclear material less suitable for use in a nuclear weapon, or less prone to diversion for such use, can be achieved in three differ... more

Sodium is highly compatible with the reactor materials, which essentially rules out corrosion problems for the life of the plant. The first reactor to demonstrate inherent safety features that would eliminate the potential for catastrophic accidents like Fukushima was sodium cooled. Sodium is a highly efficient coolant compared to water, meaning that the system can operate at low pressure and hi... more

Molten lead is a very heavy coolant that provides advantages for radiation shielding, heat removal, and relative compatibility with the steam system. Lead has also been combined with bismuth to form a coolant with a lower melting temperature coolant, which simplifies design and improves operability. Both concepts would operate at low pressure.

Lead presents some unusual engineering challenges.... more

Molten salt has some interesting benefits in reactor design, with unequaled flexibility. On the plus side, molten salt is an efficient high-temperature coolant whose transparency enables inspection and maintenance of components. The reactor fuel can be dissolved in the salt to allow continuous removal of impurities, or the salt can be used to cool more conventional solid fuel. Both concepts woul... more

Within GIF, helium is used as a coolant in two quite different system concepts. Helium has the advantage of being transparent, completely inert, and remains a gas at all temperatures and pressures of interest. Gas-cooled reactors operate at high pressure, but lower than current water-cooled reactors.

For reactor designers, the challenge with helium coolant is that its heat removal and retentio... more

Helium shortages can sometimes appear in the current market because it is thin. If a large market for gas-cooled reactors develops, sufficient helium could be captured from oil well production to satisfy the increased demand. Also, helium would be expected to behave like other commodities — short-term supply restrictions would drive up prices, stimulating more exploration and development.

Ordinary water subjected to very high pressure becomes supercritical water, which has a high boiling temperature, greater density, and enhanced chemical reactivity. Supercritical water has been successfully applied in modern coal plants around the world. Its advantages as a reactor coolant are much higher generating efficiency and a wealth of industrial experience that can be applied.

The disa... more

In 50 years of nuclear energy development and deployment, the safety performance of nuclear power plants has been continuously improved. Some of these improvements are due to adaptation to state-of-the-art, as occurs with all technologies. Others are the result of lessons learnt following incidents and accidents that have occurred (Three Mile Island 1979; Chernobyl, 1986; Fukushima, 2011) and of... more

The Forum is an organization that has a specific goal: the development of concepts for one or more Generation IV systems that can be licensed, constructed, and operated in a manner that will provide a competitively priced and reliable supply of energy to the country or countries where such systems may be deployed, while satisfactorily addressing nuclear safety, waste, proliferation and public pe... more

It will take at least two or three decades before the deployment of commercial Gen IV systems. In the meantime, a number of prototypes will need to be built and operated. The Gen IV concepts currently under investigation are not all on the same timeline and some might not even reach the stage of commercial exploitation.

Examples of advanced reactor prototypes (steps towards Gen IV designs) cu... more

The GIF Experts Group has drafted a position paper on the use of Thorium in the nuclear fuel cycle.

The PR&PP methodology is a systematic and comprehensive tool for assessing and optimizing, at all stages of design, the level of proliferation resistance and physical protection of a nuclear energy system, or components thereof. It is a “pathways evaluation” approach which can account for a full range of hypothetical proliferation or terrorism scenarios (including diversion, misuse, clandestine ... more

The PR&PP methodology was developed to address one of the four goals identified for future nuclear energy systems in the 2002 Generation IV Roadmap (i.e., next-generation power reactor designs that will see commercial deployment beyond 2030): “Generation IV nuclear energy systems will increase the assurance that they are a very unattractive (i.e., present significant barriers) and the least desi... more

The level of effort depends on the stage of design, the range of challenges evaluated, and the needs of the user performing the evaluation. The methodology is adaptable to differing needs. It can involve a single PR&PP expert with subject matter expert support from design staff (for a scoping study), or a team, requiring a few staff-months to a few staff-years.

The time requirement can be as little as a few weeks of work for a scoping study that evaluates the system response a small number of representative PR or PP challenges, to a year or more of work to evaluate response to a comprehensive spectrum of challenges.

The results take the form of tables of quantitative or qualitative measures indicating material being obtained, difficulty of obtaining the material and likelihood of detection. These results can be presented in various graphical or tabular forms, depending upon the needs of the individual user and the audience they will be presenting to.

The range of users of the methodology includes designers, program policy makers, national regulators, international agencies, and other stakeholders.

Familiarity with the PR&PP methodology, the system design, and the general requirements of non-proliferation (e.g. international safeguards) and physical protection. Note that this combined expertise need not reside in a single evaluator, but can be represented by an assessment team.

PR&PP is a design tool that evaluates the system response to a spectrum of potential PR&PP challenges (e.g., diversion, clandestine program, break-out scenario and terrorism), and can also be used by customers or policy makers in guiding decisions; INPRO is a best-practices checklist aimed mainly at assisting embarking countries in making decisions. INPRO is a broad assessment, including high-le... more

PR&PP incorporates International Atomic Energy Agency (IAEA) safeguards as external components (sometimes referred to as “extrinsic measures”) of the nuclear energy system being assessed. PR&PP can be used by designers at an early stage to assess where and how one might implement safeguards, in order to guide conceptual design decisions. Safeguards is one feature of a good design that enables th... more

Generally PR applies to national actors, and PP to sub-national actors, although there can be interaction between these two.

There are possible synergies between PP&PP and safety/reliability if assessed early enough in the design process and possible conflicts that may be addressed at this time. Even at the earliest stages of conceptual design it is recommended that, in addition to representative safety challenges, designers perform qualitative assessments of the potential system response to representative PR and PP c... more

PRPP can be performed at the earliest stages of design, and then revisited periodically and detail added as a design progresses and more detail is known.

PR&PP is designed for the assessment of nuclear energy systems, with no specific technology dependence.The elements of the fuel cycle (i.e., components of the fuel supply, reactor, or spent-fuel management architecture) that are included in the assessment are dependent upon the user’s needs.

There are other assessment methodologies (e.g. INPRO). The methods are complementary. INPRO assessments can assure that best practices have been considered, and adopted where appropriate, in system design. PR&PP assessments can assure that the system response to PRPP challenges will be acceptable.

The methodology is ready for use, currently as Revision 6. It will receive updates as feedback is received on implementation, and as the field of knowledge in non-proliferation and physical protection evolves.

Benefits include synergies with safety and economics, reduction of risk for schedule slippage, efficiencies in implementing PR&PP-related system design components, guidance on design decisions with maximum flexibility to early design stage.

The PR&PP Evaluation Methodology report is available online. The journal Nuclear Technology provides several articles discussing the methodology and providing examples of its application, in Vol. 179, pgs. 1-96, July, 2012.