IAEA (1997a) defines advanced nuclear plant designs as those designs of current interest for which improvements over their predecessors and/or existing designs are expected. Depending on the amount of modifications implemented, advanced reactor designs can be categorized evolutionary or innovative. An evolutionary design is an advanced design that achieves improvements over existing designs through small to moderate modifica­tions, with a strong emphasis on maintaining design proveness to minimize technological risks. The development of an evolutionary design requires at most engineering and confirmatory testing. An innovative design is an advanced design which incorporates radical conceptual changes in design approaches or system configuration in comparison with existing practice. Substantial research and development efforts, feasibility tests, and a proto­type or demonstration plant are required prior to the commercial deploy­ment of this type of design.

An alternative classification was coined by the Generation IV International Forum GIF (2002), which divided nuclear reactor designs in four genera­tions. The first generation consisted of the early prototype reactors of the 1950s and 1960s. The second generation is largely made up by the commer­cial power plants built since the 1970s and that are still operating today. The

Generation III reactors have been developed in the 1990s and include a number of evolutionary designs that offer improved performance, safety and economics. After the increased interest in nuclear power seen in the first decade of the twenty-first century, additional improvements are being incor­porated into Generation III designs, resulting in several concepts that are actively under development and seriously considered for near-term deploy­ment in various countries. The Generation III designs loosely correspond to what in the ARIS system are called evolutionary designs (IAEA, 2010) and it is expected that they will constitute the bulk of the new nuclear plants built between now and 2030. Beyond 2030, it is anticipated that new reactor designs will address key issues such as the closure of the fuel cycle or pro­liferation concerns while possibly ensuring competitive economics, safety and performance. This generation of designs, the Generation IV, consists of innovative concepts in which substantial development is still needed.

Traditionally, nuclear reactors have been classified depending on the energy of the neutron spectrum they use to produce the fission in the fuel, or depending of the coolant they use to extract the fission energy from the core. With regard to the first criterion, nuclear reactors can be thermal when using low energy neutrons and fast when using much higher energy neu­trons that are not slowed down by a moderator. With regard to the coolant, nuclear reactors can be classified as water-cooled reactors (WCR), gas — cooled reactors (GCR), liquid metal-cooled reactors (LMR) and molten salt-cooled reactors (MSR). Water-cooled reactors at the same time can be classified as boiling water reactors (BWR), in which the core is at relatively low pressure and the coolant is allowed to boil; and pressurized water reac­tors (PWR), in which the core is kept at high pressure and the coolant remains in a liquid state. Water-cooled reactors can also be divided into light water reactors (LWR) and heavy water reactors (HWR) that use deu­terium water. While most HWRs belong to the pressurized water reactor type, and are also termed pressurized heavy water reactors (PHWR), some advanced designs use the boiling water reactor concept. As will be seen in upcoming sections, several advanced designs are what is called (IAEA, 1997a) an integral design, which refers to a reactor design in which the whole reactor primary circuit, including, for instance, pressurizer, coolant pumps, and steam generators/heat exchangers, as applicable, is enclosed in the reactor vessel. Finally, depending on the size of the plant, nuclear designs can be classified (IAEA, 1999a) as small (less than 300 MWe), medium (between 300 and 700 MWe) and large (more than 700 MWe). Although innovative reactor designs do not always fit the following norm, in general it can be said that most water-cooled reactors and gas-cooled reactors are thermal reactors, while most fast reactors are cooled by liquid metals or molten salts.

264 Infrastructure and methodologies for justification of NPPs

Consideration of nuclear safety begins on or before the first day of a pro­posed project; this chapter is devoted entirely to a description of this aspect of plant justification. At the same time it must be recognized that all of the earlier considerations lead up to safety in actual operation — the plant is safe in the sense of radiological risk until its nuclear fuel materials arrive on site. From that day until the day that the licence of the plant is finally transferred to a second licensee or until the need for a radiation-related — licence is no longer required, it is the operating organization that is ulti­mately responsible for its safety, within the scope of its operating licence and in accordance with national standards and regulations.

The following is taken verbatim from the US Nuclear Regulatory Commission White Paper on risk-informed and performance-based regula­tion (USNRC, 1975):

A ‘risk-informed’ approach to regulatory decision-making represents a phi­losophy whereby risk insights are considered together with other factors to establish requirements that better focus licensee and regulatory attention on design and operational issues commensurate with their importance to health and safety. A ‘risk-informed’ approach enhances the traditional approach by: (a) allowing explicit consideration of a broader set of potential challenges to safety, (b) providing a logical means for prioritizing these challenges based on risk significance, operating experience, and/or engineering judgment, (c) facili­tating consideration of a broader set of resources to defend against these challenges, (d) explicitly identifying and quantifying sources of uncertainty in the analysis, and (e) leading to better decision-making by providing a means to test the sensitivity of the results to key assumptions. Where appropriate, a risk-informed regulatory approach can also be used to reduce unnecessary conservatism in deterministic approaches, or can be used to identify areas with insufficient conservatism and provide the bases for additional requirements or regulatory actions.

Risk-informed decision-making is an on-going activity that continues throughout the life of the plant. It is based on the safety assessment of the power plant as it exists at a given point in time, including all changes, updates, and ageing effects that are important to safety (GSR Part 4, 2009). The following is taken verbatim from the GSR document, as a statement of the necessary background for risk-based decision making:

The responsibility for carrying out the safety assessment rests with the respon­sible legal person; that is, the person or organization responsible for the facility or activity — generally, the person or organization authorized (licensed or reg­istered) to operate the facility or to conduct the activity. The operating organi­zation is responsible for the way in which the safety assessment is carried out and for the quality of the results. If the operating organization changes, the responsibility for the safety assessment has to be transferred to the new operat­ing organization. The safety assessment has to be carried out by a team of suitably qualified and experienced people who are knowledgeable about all aspects of safety assessment and analysis that are applicable to the particular facility or activity concerned.

Clearly, the operating organization is expected to establish the infrastruc­ture for carrying out the safety assessment to the satisfaction of the national regulatory agency. In addition, it is essential to find a proper framework for carrying out a satisfactory decision-making process to enable risk-informed decisions.

Deterministic effects can be attributed to specific NPP exposures with a high degree of confidence under the following conditions:

• The dose incurred was higher than the relevant dose-threshold for the specific effect.

• In addition, an unequivocal pathological diagnosis is attainable ensuring that possible competing causes have been eliminated.

Only under both of these conditions may the occurrence of the effect be properly attested and attributed to the exposure. One exception to this general rule could be specific situations of radiation exposure to the lens of the eye that might be sufficient to induce opacities, a situation that may be familiar in interventional radiology but should not occur at NPPs.

According to the international recommendations (IAEA, 2007) on nuclear emergency matters, the practical goals of emergency response are:

• To regain control of the situation

• To prevent or mitigate consequences at the scene

• To prevent the occurrence of deterministic health effects in workers and the public

• To render first aid and to manage the treatment of radiation injuries

• To prevent, to the extent practicable, the occurrence of stochastic health effects in the population

• To prevent, to the extent practicable, the occurrence of non-radiological effects on individuals and among the population

• To protect, to the extent practicable, property and the environment

• To prepare, to the extent practicable, for the resumption of normal social and economic activity.

The goals of emergency response are most likely to be achieved in accor­dance with the principles for intervention by having a sound programme for emergency preparedness in place as part of the infrastructure for protec­tion and safety. The practical goal of emergency preparedness is to ensure that arrangements are in place for a timely, managed, controlled, coordi­nated and effective response at the scene and at local, regional, national and international levels to any nuclear or radiological emergency.

Nuclear emergency preparedness is a long and continuous process that begins with the selection of the site to build a nuclear facility, giving due consideration to the circumstances — geographical, demographic, geological, hydrological, agricultural and social — that characterize the selected loca­tion, continues during the design and construction phase with the imple­mentation of emergency systems and procedures, and is completed while the plant is in operation through the maintenance plan operability.

14.2.1 Need for national policies and strategies

Spent fuel and radioactive waste will be generated from the first day of operation of a nuclear power plant. It needs to be taken care of through intermediate storage, treatment and conditioning, possible reprocessing and final disposal, steps that might very well stretch out over 100 years or more. Introduction of nuclear power involves a long-term commitment for the country and the industry involved. It is thus important to develop policies and strategies for their management, as well as a stable legal system, at an early stage of the decision process for implementing nuclear power in a country. The policies should include a general plan for the spent fuel and waste management systems needed and a clear delineation of the respon­sibilities to implement the different steps as well as a clear and stable system for the financing of these activities.

The importance of an early development of the principles and responsi­bilities for spent fuel and radioactive waste management has long been recognized. The IAEA has developed several safety standards and technical publications that are applicable. Guidance for development of national nuclear power programmes, including spent fuel and radioactive waste management, can be found in the so-called milestones document IAEA (2007b). More specific guidance for policy and strategy development for spent fuel and radioactive waste management can be found in IAEA (2009b). Some general conclusions are:

• A spent nuclear fuel and radioactive waste management infrastructure is a necessary element to be available when implementing nuclear power programmes.

• The development of the infrastructure requires a systematic stepwise approach lasting for several decades.

• Thus the building of the waste management infrastructure and the for­mulation of national spent fuel and radioactive waste policies and rel­evant strategies should be initiated in the early stages of planning nuclear power programmes.

O&M costs of nuclear power plants are the non-fuel cycle costs for plant operation and related services and are generally divided into fixed (inde­pendent of electricity generation) and variable cost components. Essential O&M cost components are salaries for plant staffing and costs for materials, liability insurance, decommissioning, security, outsourced support services, administration and maintenance.

The O&M costs are further determined by the size and type of plant and the mode of operation (load-following or base-load operation). The number of similar units at a particular site has a strong influence on the O&M cost components.

Planning authorities

All decisions to build new plant will require review by a competent author­ity in the affected jurisdiction. This is recognised by the IAEA as a funda­mental feature of nuclear law and commonly referred to as the permission principle. Their Handbook on Nuclear Law describes the principle in the following terms:

. . . this principle holds that, unless specifically exempted, any activity related to the use of nuclear material and technology should be permitted only after competent authorities have determined that it can be conducted in a manner that does not pose an unacceptable risk to public health, safety and the envi­ronment. . . Where a nuclear related activity is deemed to pose a significant health or safety risk, governments require that an explicit authorization be issued by the regulatory body following an application and review process. . . The national legal infrastructure in each State will determine the conditions and procedures applicable to such authorizations and notifications, including any limits on the regulatory body’s power to impose additional requirements (Stoiber et al., 2003, pp. 34-35).

Prior to 2009, the UK planning system required the consent of the Secretary of State for the construction of any form of power station with a capacity greater than 50 megawatts. This was a requirement imposed by Section 36 of the Electricity Act 1989. The grant of consent operated in such a way that the applicant was usually deemed to have also been given plan­ning permission (see Town and Country Planning Act 1990 (TCPA, 1990, section 90(2)). Although to a certain extent the discretion of the Secretary of State was fettered by the evidence presented (including that from EIAs and public inquiries) which had to be judged against set criteria, the powers provided were extensive.

The Section 36 consenting procedure no longer applies in the UK and it has been replaced by a new regime introduced by the PA 2008 (McCracken, 2009). It was widely felt that the Section 36 regime was unsuitable for con­senting major infrastructure projects and too time-consuming. The chal­lenge was ‘to transform the regime for major infrastructure projects in order to achieve outcomes that are both faster and fairer; both more efficient and more accountable; and which both ensure more timely delivery, and improve the ability of communities and individuals to participate in the system’ (Kelly, 2008, p. 2). The Infrastructure Planning Commission (IPC) was created to decide applications relating to ‘nationally significantly infrastruc­ture’ such as generating stations, highways, airports, railways and hazardous waste facilities. Within a few months of its formation, the coalition govern­ment decided to abolish the IPC and replace it with another new body called the Major Planning Infrastructure Unit (MPIU) which will operate as a specialised branch of the Planning Inspectorate. The key reason for this change was that the coalition government wanted to ensure that elected ministers would be vested with decision-making powers rather than une­lected IPC commissioners. At the time of publication, the legislation which is intended to replace the IPC has not been given effect and the IPC con­tinues to be the relevant decision-making body in the intervening period. Despite the impending reform, it is expected that most of the changes introduced by the PA 2008 will be retained going forwards. The 50 mega­watts threshold continues to apply to generating stations, which effectively means that all new nuclear power plants will have to seek development consent from the IPC/MPIU. Schedule 1 of the PA 2008 fleshes out impor­tant constitutional details of the IPC and provides the Secretary of State with the powers to appoint the Commissioners. The creation of a specialist body such as the IPC/MPIU requires the appointment of Commissioners/ Ministers with the necessary expertise to assess major development pro­posals. Although the IPC (until it is replaced by the MPIU) is vested with most of the power to determine applications falling within their remit, the Secretary of State has retained residual powers (Sections 110-113 of the PA 2008) to intervene in the interests of defence or national security. The new planning regime in the UK shifts power from the government to the IPC/MPIU, but these steps towards independence have been offset by a suite of measures that have been introduced to ensure parliamentary accountability (Tromans, 2010, p. 141).

Regulators

The regulators will have an ancillary role to play in shaping the land-use planning debate. The authority tasked with overall responsibility for the regulation of nuclear installations will generally be involved in key planning decisions, since they will bear most of the regulatory responsibility for the plant during its lifetime. In the UK, this function is performed by the Nuclear Directorate (ND), a specialist organisation within the Health and Safety Executive (HSE), responsible for setting, monitoring and enforcing safety and security standards on nuclear sites. There are a number of other regulators that will have an interest in the planning debate, such as the Environment Agency (EA), the Office for Civil Nuclear Security, the Department for Transport and the coastal authorities. It is imperative for applicants to engage with the regulators from the outset because the IPC/ MPIU will ‘expect the applicant to have involved the relevant regulators at the pre-application stage so that the applicant can incorporate the regula­tors’ requirements in proposals’ (draft Nuclear National Policy Statement EN-6, paragraph 3.4.4).

Surface water may get contaminated through direct discharges to water bodies or through fallout from radioactive clouds. All contaminated waste water from the operation of a NPP is collected and treated in the liquid waste treatment system. This normally includes a high efficiency filtration system to retain particulate materials, followed by ion exchange to retain dissolved ions and also by a residual water evaporation system. At the end of these treatments pure distilled water is obtained; it can be recycled into the plant but any surplus of water has to be released to a nearby water body under strict control. Although of high efficiency, all these waste water treat­ment processes cannot retain all radioactive materials; moreover tritium substitutes hydrogen in the water molecule and it cannot be separated by any of the three processes mentioned above.

Tritium is a fission product — about one tritium atom is produced every 10,000 fissions. In PWRs tritium is also produced by activation of boron added to the coolant to control reactor core reactivity that is used in such reactors and with lithium also used in PWRs to control water pH. Tritium (half-life 12.26 years) is continuously produced in the stratosphere by cosmic radiation reacting with oxygen and nitrogen, from the stratosphere it gradually descends to the lower parts of the atmosphere by natural dif­fusion, and it ends in the ocean and terrestrial waters. As it is generated and decays constantly, it has reached an equilibrium estimated at about one million curies. It is against this natural background that tritium generated in NPPs and reprocessing facilities has to be measured.

The behaviour of the released nuclides to surface water, especially tritium, has to be predicted to measure the potential effects of such releases on the health and safety of the affected people and on the environment. Surface water dispersion and dilution parameters have to be measured by dedicated processes to determine water flows, and the transfer mechanism by which nuclides may reach humans. With all these parameters dispersion models are developed which also take into account all potential phenomena that control the behaviour of the different contaminants. These studies are con­ducted at least one year before starting plant construction and are main­tained during the whole operating life of the NPP.

As in the case of meteorological data, surface water dispersion and dilu­tion data and models are essential at the time and during an accidental release of radioactive products to properly manage the emergency use of such waters. In these cases dispersion and dilution data have to be supple­mented with the data and dispersion models of the country’s central hydro­logical agency. The 2011 Fukushima event released substantial amounts of contaminated water with radioactive nuclides to the Pacific Ocean with the potential of becoming concentrated in the bodies of fish and marine food products, thus requiring the definition of accepted concentration limits for human consumption.

The IAEA safety guide already mentioned (IAEA, 2002b) indicates the ways and means to obtain surface water data and develop the site water body’s dispersion models. The guide describes how to select and display a data gathering system appropriate to the hydrology of the region where the plant is located. Differences between river, open coastal, estuarine and artificial lake receivers are marked. The guide also describes methods to develop appropriate dispersion and dilution models to clearly determine the different pathways through which contamination can reach humans. Such models are also an essential part of the theoretical estimation of the potential radiation doses that the affected population may receive from surface water pathways. The model is also essential in the epidemiological studies generally conducted around nuclear sites.

Dispersion of radioactive material through ground water

Ground water may be contaminated by leakages from buried pipes carrying contaminated fluids, through seepage and infiltration of surface water that has been contaminated and from interactions with contaminated surface waters. Several instances of tritium presence in ground water from NPP underground leaking pipes have been recently reported. Ground water uses include human consumption and irrigation, pathways that may bring tritium into human contact. Therefore the protection of aquifers from such events should be prevented and a geological barrier should be considered.

A description of the ground water hydrology at the local and regional level is then required to assess the behaviour of any contaminant, its poten­tial migration and dilution, the retention characteristics of the soil and the physicochemical properties of the materials, mainly its retention properties. From this information a model is developed to estimate the radionuclide pathways during normal operation and under accident conditions.

As in the case of surface waters, IAEA (2002b) describes which data should be collected, that may require drilling boreholes for geophysical and tracer studies. The models will serve to estimate the expected contamination of ground waters at the point of use, and to assess the doses received by the exposed population and for the management of such waters in case of accident.

19.11.1 General

The draft contract (DC) document constitutes the draft of the final contract proposed by the owner and which he intends to sign with the selected bidder. Again in this case, if the contract concerns the turnkey purchase of a plant (single-package approach), there will be one main contract; in the event of a multi-package (two or more) approach, a separate contract will be drafted for each package included in plant procurement.

The DC document should basically contain:

• The owner’s proposed terms and conditions for the final contract, cover­ing all the legal, administrative, organisational, technical, economic, financial and commercial aspects of the transaction that require agree­ment between the owner and the successful bidder in the final contract

• The identification of the ‘contract documents’, that is, all the documents that will form part of the final contract, listed in the order of precedence to be applied vis-a-vis one another in case of discrepancy.

Far from being a matter exclusively for engineers or for lawyers, the preparation of the terms and conditions should preferably involve a

multi-disciplinary team of experts for the technical aspects, lawyers for the legal aspects, as well as experts for licensing and permitting, insurance and finance. Including the participation of a lawyer (or lawyers) familiar with the laws of the owner’s country and with international contracting is espe­cially advisable.

As regards nuclear fuel, a single contract may be devised for both the plant and the nuclear fuel, or separate contracts may be prepared for the plant supply and for the nuclear fuel. The latter approach is more frequent.