LLW is defined as waste that contains only limited amounts of long-lived radionuclides, but still requires robust isolation and containment for periods up to a few hundred years. It is suitable for disposal in engineered near­surface facilities. ILW has a radioactivity content that requires disposal at greater depths, of the order of tens of metres to a few hundred metres. Disposal of ILW was discussed in Section 14.4.6.

Disposal facilities for LLW have been in operation for more than 20 years in several countries around the world. Some of the earlier disposal facilities had a very simple design and the waste was essentially disposed of in trenches above the water table and with a watertight cover. The more modern disposal facilities have a more engineered design with several bar­riers against release. Two different types can be distinguished, engineered surface facilities and engineered facilities in rock chambers. Both types of facilities can superficially be described as disposal in a house that should remain tight for water intrusion, but which still has control over any water coming out from the house. In all cases the multiple barrier approach is being used to ensure long-term containment of the radioactive elements.

Two examples of near-surface engineered facilities are the Centre de Stockage de l’Aube (CSA) in France and El Cabril in Spain, which have been in operation since the early 1990s. Similar facilities are in operation or under construction in several other countries, e. g. Japan, China and Belgium.

In CSA the disposal is made in large concrete structures (25 x 25 x 8 m) that are built on the surface (Fig. 14.13). The conditioned waste packages are placed in the concrete structures and subsequently surrounded by con­crete. When one concrete structure is filled a reinforced concrete lid is cast, including an impermeable cover. The disposal operations take place under a temporary roof that can be moved from disposal structure to disposal structure. Underneath the concrete structure there is a channel system for collection and control of any water that might come out of the structure.

Each concrete structure can house about 2500 m3 of conditioned waste. The whole CSA site is designed for 1,000,000 m3. After completion of the dis­posal the concrete structures will be covered by clay and earth and grass will grow on top of the mounds thus made (Fig. 14.14). The site is intended to be surveyed, including control of any effluents, for at least 300 years, i. e. approximately 10 half-lives for cesium-137 and strontium-90. The long-term safety of the disposal (>300 years) is based on the low content of long-lived radioelements, the characteristics of the waste form and packages, the watertight concrete structure and finally the surrounding geology with a low water flow.

LLW disposal facilities in rock chambers at about 100 metres depth are in operation at Olkiluoto and Loviisa in Finland and Forsmark in Sweden (SFR). Other similar facilities are under construction in Korea. In some countries disposal of LLW is planned at greater depth, e. g. in Germany (Konrad) and Canada (Bruce).

In SFR the repository has been placed between 50 and 100 metres below ground level. It consists of several different rock chambers that have been adapted to the type and activity level of the waste (Fig. 14.15). Some very low-level waste is disposed of directly in the rock chambers with no extra barriers than the waste package itself and the rock, while the more active LLW is placed in a large concrete silo (50 m high, 50 m diameter) and sur­rounded by concrete. Between the concrete silo wall and the rock a buffer of bentonite clay is introduced to further reduce any leakage. The multiple barriers are thus the waste form and package, the concrete structures, the bentonite clay and the rock. The facility has been built with the intention of making it possible to abandon it without further surveillance once it has

been filled. Whether this will happen in reality is of course a decision to be taken by future generations.

Very low-level waste (VLLW) is defined as waste that does not meet the criteria for exemption, but has such low activity content that it does not need a high level of containment and isolation. It is thus suitable for dis-

posal in near-surface landfill-type facilities. An example of such a disposal facility is Morvilliers in France (Fig. 14.16). These types of facilities should also be part of the infrastructure needed in any individual country introduc­ing nuclear power plants. They will be needed at the time of dismantling a power plant.

14.6 Conclusions

The management of radioactive waste has sometimes been seen as the Achilles heel of nuclear power production. It will require very long-term considerations also for the period after the nuclear power production has been stopped. Some of the radioactive wastes are very hazardous and will require very careful handling and management. They are also long-lived and will require isolation over hundreds to hundreds of thousands of years. The volumes to be handled are, however, quite small and the utmost care can be exercised without significantly increasing the cost of nuclear power production (a few percent of the production cost) or putting undue burdens on the future. All countries with nuclear power plants have an active pro­gramme to responsibly manage their radioactive waste by treatment, con­ditioning and storage today and by operating or developing disposal facilities for tomorrow. Preparations for disposal of low-level waste from reactor operation should be considered from an early phase of planning nuclear power as these types of waste will occur from the start of the reactor. They should be part of the infrastructure necessary for starting a nuclear power programme. Also the future handling of the spent nuclear fuel should be considered at an early stage, although construction of facili­ties will only be needed decades later.

In this chapter several examples of the management principles, strategies and methods have been described. It should be clear that the final choice of strategy will depend on the national conditions, e. g. size and prospects of the nuclear power programme, industrial capacity and geological condi­tions. It will often be too early for a country considering the introduction of nuclear power to decide from the beginning what strategies should be chosen, e. g. concerning reprocessing and recycling and concerning disposal. It is, however, very important that good comprehension of the options is developed early and to see how different options could be implemented in the specific country. It is also very important to ensure from the start of nuclear power production that funding will be available to take care of the waste (including decommissioning of the power plants) when needed, taking into account that many of these costs will appear long after the power production has stopped. It should be realized that introduction of nuclear power implies an undertaking for a hundred years or more.

In recent years, particularly in western countries, there has been an increas­ingly marked distinction between giving information, which is a ‘top-down’ process, and stakeholder involvement, which tends to involve groups and citizens who declare an interest in nuclear choice in the decision process. The degree of citizen involvement in the decision process is variable, ranging from compulsory involvement or (as is more often the case) simply con­sultative advice. Whichever, stakeholder involvement requires giving suffi­cient information to stakeholders, and so requires real transparency and access to expertise. However, other information processes may have differ­ent purposes: they may have an educational goal, which requires ‘objective’ information on the advantages and drawbacks of all energy sources, and an explanation of geopolitical and economic constraints which limit and struc­ture energy choices. Conversely, they can tend to involve or influence citi­zens’ opinions, for instance through advertising campaigns, where the goal is less to supply knowledge than to obtain support.

There are many kinds of ‘stakeholder involvement processes’: national or local public debates; Local Information Councils (CLI), in France, in the neighbourhood of nuclear plants; a Dialogue Forum in the Russian Federation; COWAM in the EU; and numerous other initiatives. These processes don’t have the same impact on public decision everywhere: in France, national debates under the aegis of CNDP (‘National Commission of Public Debate’) have a legal status and are compulsory for some deci­sions about the building of large energy facilities; again in France, CLIs are compulsory near nuclear sites but they have no decision mandate; in the UK, the 2006 consultation on nuclear policy had no compulsory value; the Swedish process of local consultation to select a disposal site has had a decisive impact on the final choice, etc. The political impact of consultative or participative processes in public decisions to launch a nuclear programme depends strongly on local laws and on national political culture. For instance, in 2005-2006, in France, the government referred to the CNDP to organize a national public debate before passing a new Act on waste management. This public debate was implemented by organizing 13 meetings, some in Paris and in other larger cities (Lyon, Marseille, Nancy) and others in the vicinity of possible waste storage or disposal sites. The schedule was very strict, with the participation of nuclear sector professionals, government representatives, NGOs and independent experts. Some anti-nuclear NGOs refused to participate. Public participation was weak in Paris and in the large cities far from the sites but it was significant near the potential disposal sites. The meetings and an Internet consultation allowed a long list of ques­tions and fears about radioactive waste management to be collected, and for answers to be given to those questions. This also made it possible to take these fears into account when proposing the Act, by including clauses, for example, to ensure the reversibility of nuclear waste disposal for a period of 100 years. This whole process probably increased people’s knowledge and understanding of waste management issues in France, but it did not increase the wider public interest in them. Some years later, the question of radioactive waste management remains, for the public at large, a problem with ‘no solution’.

The following lessons can be learned from the experience of public debates in France:

• Be transparent about the process and about the role of debate in elabo­rating a decision; it is important to explain the impact of public debate on the decision (whether about an Act or selection of a site for a nuclear facility). In this regard, several qualitative and quantitative studies con­ducted in France (IRSN, The French Perception of Risks and Security, Barometer, 2010), and quantitative studies implemented in the EU show that a majority of citizens delegate technological decision to experts, provided the experts report their arguments and possible doubts or disagreements, and provided information is shared with the public. Moreover, the Eurobarometer on Nuclear Safety (2010) showed that ‘only around one in four Europeans would like to be directly consulted in the decision-making process regarding the development and updating of energy strategies’.

• Give complete information about all energy sources and allow people to be able to build their own understanding of realistic choices: is there an alternative to nuclear power and, if so, what are the advantages and drawbacks of each alternative solution?

• Clearly define the process and the different steps from opportunity study to decision, and the rules, limits and schedule of public consultation.

• Listen to all the fears and questions raised about a nuclear project and provide answers to all of them.

16.4 Conclusion

A gap remains between the social impact of nuclear power and people’s perception of its impact. This gap is more acute in non-nuclear countries, and the more nuclear power is experienced, the better it is accepted. But contradictory phenomena influence the evolution of public perceptions. A better understanding of energy questions and of environmental and eco­nomic issues will probably contribute to a better acceptance of nuclear power, and the growing interest in developed and (more and more) devel­oping countries for nuclear power as part of a low-carbon energy strategy may have a driving effect. In the same way, continuous improvements in safety may have a positive effect; conversely, however, a severe accident like Fukushima will have an adverse effect everywhere in the world, even if the needs of nuclear power in an energy mix remain exactly the same as before the accident. There is a growing need for stakeholder involvement in the decision process, which has ambivalent consequences: it can favour objective discussion among different parties about the advantages and drawbacks of the nuclear choice; however, many people in the public at large who have no definite opinion on nuclear power may in fact be con­vinced by nuclear opponents, of whom there are many giving their views in public debates. As a result, nuclear decisions must be based soundly on a technical and economic opportunity study, and any such decision must be supported by a majority of political decision-makers and by the business community. The most difficult decision to make is the decision for the first plant or the first units, because infrastructure costs and possible public reluctance are the same for one plant or for a whole programme. Such a decision may have a very positive impact on economic, technological, indus­trial and educational development in a country but requires sufficient politi­cal stability to guarantee safe, secure and sustainable practice.

INSAG has established four specific safety principles applicable to the siting of a NPP. They address the following issues: the external factors affect­ing the plant; the radiological impact on the public and the local environ­ment; the feasibility of emergency plans; and the ultimate heat sink provision (INSAG, 1999).

The principle for the external factors affecting the plant is formulated as follows:

Principle 1: The choice of site takes into account the results of the investigation

of local factors that could adversely affect the safety of the plant.

This principle recommends the identification of local factors which must be considered in the design of the plant. They are generally classified into two groups: natural events and those created by human activities. Among the first, the characterization of seismic events and geological, hydrological and meteorological extreme disturbances are the most relevant. Among the second, contaminations, explosions and deflagrations of flammable and toxic gas releases in the proximity of the plant are the major concerns. The studies are aimed at evaluating the expected frequency of these natural phenomena and human-induced acts as a function of their magnitude. The designers need the magnitudes and characteristic parameters of all these natural and human-induced events to be sure that they will be properly included in the design basis in such a way that the plant will cope with the phenomena under consideration.

The principle concerning the plant’s radiological impact on the public and the local environment is presented as follows:

If the owner requires the supplier to provide technology transfer services in specific areas of the nuclear plant project, this should be indicated in a specific section of the SS document, which could include typical scope items such as training in accident analysis, training in probabilistic safety analysis, training in specific computer code applications and software modifications, to name a few.

19.7.3 Options

The SS document should have a section specifying the scope options that the owner requires from the bidder. The owner reserves the right to exercise each option, once it has been technically and financially evaluated. Options are a way for the owner to explore the convenience of including in the sup­plier’s scope certain technical solutions for the structures, systems and components, or to modify the scope boundaries and make the decision at a later stage, once bidder information is available and has been evaluated.

This section should also make provisions for the inclusion of options proposed at the bidder’s initiative. It may count on technical alternatives prepared by the bidders to the technical requirements specified in the BIS.

The owner should make it clear to the bidders that they should be com­mitted first and foremost to complying with the BIS requirements, before any options be considered (be they requested by the owner or proposed by the bidder as technical alternatives). Otherwise these options or alterna­tives would be considered as exceptions to the BIS.

Bidders shall also be requested to submit complete technical information in their bids regarding options and alternatives, to facilitate evaluation by the owner.

The construction license requires the submittal of a PSAR, already described in Section 20.3.3. As part of the submission, the licensee has to provide details of the project management arrangements and quality assurance provisions. The RB seeks assurance that the work will be conducted safely and in accordance with the environmental and transportation requirements of the terms of the license, and that the installation conforms to the approved design.

The safety assessment of this documentation requires a major display of the RB’s resources, and arrangements for obtaining external help and advice may need to be made. The analysis covers all the chapters of the PSAR and related information, conducted in accordance with pre-stated procedures. All evidence provided by the operator in support of the request for a construction license needs to be checked and verified by the RB, par­tially by scrutinizing the operator’s analyses but also often by performing independent analyses. The SER for the construction license will form the basis for the content of the license, its limits and conditions.

The analysis of the chapter on potential accidents requires expertise, as it is necessary to verify that potential accidents can be avoided or control­led. A deterministic approach is generally used: a set of potential accident scenarios is proposed, which the NPP design includes equipment and pro­cedures to manage. This constitutes what is called the design basis. A new methodology, a Probabilistic Safety Assessment (PSA), has started to be used as a complement to the deterministic approach. Recently, INSAG recommended integrating both approaches (INSAG, 2011).

Throughout construction, it should be ensured that, once approved, no alteration or amendment is made to the plant and equipment, or to any approved arrangement, unless the RB has approved such alteration or amendment. Normally construction schedules are divided into installation stages. The RB can specify hold points, beyond which work may not progress without its consent. Throughout construction, the RB carries out a programme of inspections, assessments and reviews of the activities per­formed. If at any stage the RB is not satisfied, a variety of options should be put into practice to improve the situation, including stopping all work until the issues in question are addressed. To achieve a high quality of systems and components relevant to safety, the components need to be qualified to properly respond to seismic and extreme environmental situa­tions. As far as possible, components that have already been proven in operation should be used. Manufacturing must conform to high quality standards.

The construction phase is considered complete when SSCs relevant to safety are tested under well-defined conditions and established standards. Examples of these pre-nuclear tests include pressure tests of the primary coolant system (including the reactor vessel), performance tests of emer­gency coolant systems, containment pressure and leakage rate tests, and electrical systems performance tests. Representatives of the RB, or special­ists working on their behalf, generally witness these tests for acceptance by the RB.

Although the human resources development programme for each country has its own unique characteristics that should be identified considering the above-mentioned factors, in the following paragraphs the human resources needs for different stakeholders will be analysed according to their main mission.

The ranges presented in the following paragraphs should be interpreted as indications of orders of magnitude of the number of specialists required for each group of activities for a new NPP with a single unit. Most data have been extracted and adapted from IAEA (2007a).

Table 6.2 summarizes the human resources requirements according to different functions or activities to be accomplished during the implementa­tion of the nuclear programme. Statistics regarding future nuclear employ­ment in the USA can be found in Clean and Safe Energy Casenergy Coalition (2009).

To help point the way towards a globalizing nuclear profession, the World Nuclear Association has worked with the IAEA, WANO and the NEA to create the new World Nuclear University. The WNU is a partnership in which these four global organizations cooperate together, and with leading institutions of nuclear learning, in activities to enhance nuclear education and leadership for the twenty-first century. The WNU partnership is sup­ported by a small multinational secretariat in London composed of nuclear professionals seconded by key governments and nuclear enterprises.

The flagship of the partnership is the WNU Summer Institute, an annual six-week event designed to educate and inspire an international group of young nuclear professionals who show promise as future leaders in the world of nuclear science and technology.

A NPP comprises a large number of structures, systems and components and these need to be maintained in a good state of repair for safe and efficient operation. Maintenance can be largely divided into preventive, predictive and breakdown maintenance. All preventive maintenance activ­ities should be well planned according to manufacturers’ recommenda­tions and executed by well-trained personnel. These schedules shall be suitably revised from time to time based on actual experience. Modern NPPs have sufficient redundancy for equipment and instrumentation items that are safety related or which are needed to be taken out of service for maintenance or calibration with the NPP in operation. Some of this equip­ment or components may be radioactively contaminated and hence will have to be decontaminated prior to maintenance work. Where this is not possible, maintenance may have to be done in shops that are equipped to handle contaminated parts. For predictive maintenance, the components have to be kept under surveillance to monitor any degradation such as by condition monitoring techniques or by trending their performance. Maintenance work is then done to prevent breakdown while in service. For certain redundant safety-related components the technical specifica­tions for operation prescribe the allowed outage time. The plant mainte­nance groups should be well equipped to complete maintenance work on such items and return them to service within the permitted time to avoid forced shutdown of the NPP.

From the foregoing it can be seen that a high level of technical compe­tence for all types of maintenance work must be developed in the plant staff. This can be achieved by getting some personnel trained in mainte­nance at other NPPs of similar design and by equipment manufacturers. These personnel in turn should train the larger number of maintenance personnel at plant site. For overhauling some of the equipment of a special­ized nature such as the turbine generator, it may be necessary to engage the manufacturer’s personnel during planned outages of the NPP. However, the overall responsibility for getting the work carried out and bringing the equipment back to service must rest with the plant personnel. Several maintenance activities are undertaken during planned outages such as the refuelling outage. The duration of such outages and consequently the plant load factor is heavily dependent on the capability of the maintenance per­sonnel to complete the work in a timely manner while maintaining a high level of quality in the work performed. It must be remembered that a well — designed and well-operated NPP can give plant load factors in excess of 90% but this is possible only when it is maintained by personnel with a high level of technical skills and in the most professional manner.

S. BILBAO Y LEON, Virginia Commonwealth University, USA and J. H. CHOI, J. CLEVELAND, I. KHAMIS, A. RAO, A. STANCULESCU, H. SUBKI and B. TYOBEKA, International Atomic Energy Agency (IAEA), Austria

Abstract: This chapter discusses the various nuclear technologies currently available for near-term deployment, as well as those in advanced stages of development that are expected to become available in the near to medium term. The chapter includes a brief overview of innovative nuclear technologies proposed for the longer term. Finally, the chapter offers some insights about the use of advanced nuclear technologies for non-electrical applications.

Key words: advanced nuclear reactor designs, evolutionary nuclear reactor designs, innovative nuclear reactor designs.

9.1 Introduction

In addition to the support required in the development of the infrastructure necessary to deploy a new nuclear program, newcomer countries have also indicated a desire to receive guidance in the process of evaluating the dif­ferent nuclear technology options.

Countries, both those considering their first nuclear power plant and those with an existing nuclear power program, are interested in having ready access to the most up-to-date information about all available nuclear reactor designs as well as important development trends. To meet this need, the International Atomic Energy Agency (IAEA) has developed the Advanced Reactors Information System (ARIS) (IAEA, 2010), a web — accessible database that provides Member States with balanced, compre­hensive and always up-to-date information about all advanced reactor designs and concepts.

In addition to having accurate information about the various nuclear technologies available, the key technical characteristics of a particular nuclear project should be clearly understood and specified at the onset of

This chapter is the copyright of the International Atomic Energy Agency (IAEA) and is reproduced by the Publisher with the IAEA’s permission. Any further use or reproduction of the chapter, in whole or in part, requires the permission of the IAEA. The chapter has been written by a staff member of the IAEA in his personal capacity and not on behalf of the IAEA or the Director General of the IAEA. The views expressed in the chapter are not necessarily those of the IAEA and that the IAEA disclaims all liability in connection with the chapter and any use made thereof.

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the project. In this way both the technical and economic benefits of the alternative nuclear power plant designs and associated technologies can be objectively assessed against the situation and the needs of each country, and the most suitable design can be selected. Nations need to follow a design — neutral systematic approach that evaluates the technical merits of the various nuclear power plant technologies available on the market based on each country’s needs and requirements.

The objective of this chapter is to help the reader differentiate among the different kinds of nuclear reactors and develop a clear picture about the current status of nuclear power technology. The chapter describes in some detail the most relevant nuclear reactor designs developed by all the suppliers/designer organizations in the world, highlights their advantages and disadvantages, and provides an update about the status of development and deployment of each one of them.

Because nuclear technology can also be used for many applications in addition to the production of electricity, and because many newcomer coun­tries are interested in these non-electric applications almost as much as they are in the production of nuclear electricity, the chapter also provides a summary of the various non-electric applications of nuclear power and the technology needed to effectively deploy them.

Protection of the plant normally is not considered in discussion of safety principles. However, all safety authorities recognize the importance of a healthy safety culture to maintaining low plant risk (i. e. excellent plant safety). All safety culture begins with senior management. Protection of the plant investment is widely recognized as one of the fundamental responsi­bilities of senior management, usually by the plant’s shareholder(s). The operating organization must justify plant protection to the owner(s). Over time, congruence of these two management responsibilities may prove to be the single most important factor in assurance of real safety within and outside the plant at all times.

Protection of the plant includes protection against damage from external hazards. In the first instance, this falls within the scope of the owner’s invest­ment protection — for example against fire, flood, wind, earthquake and other natural phenomena. Protection of plant functions under these condi­tions is, of course, to be considered as one aspect of public and staff protection.