Articles 2 and 3 of the AP specify the State’s obligation for submitting timely declarations containing additional nuclear fuel cycle-related infor­mation. In very generic terms, Article 2 requires that the State provide the IAEA with declarations containing information on all parts of a State’s nuclear fuel cycle — including that which is not required by the State’s com­prehensive safeguards agreement such as uranium mines, nuclear-related manufacturing locations, and nuclear waste sites — as well as any location where nuclear material is or may be present. This would include, for example, information on:

• Research and development activities related to its nuclear fuel cycle[52] including those not involving nuclear material

• All buildings (permanent and temporary) on each declared nuclear site, and upon request of the IAEA, identified locations outside a site which the IAEA considers might be functionally related to the activities of that site[53]

• Locations engaged in the activities relating to the manufacture and export of sensitive nuclear-related technologies[54]

• Exports, and upon a request by the IAEA, imports of specified equip­ment and non-nuclear material[55]

• Uranium mines and concentration plants, as well as thorium concentra­tion plants

• Source material which has not reached the starting point of safeguards as defined in INFCIRC/153 (Corrected)

• Exempted nuclear material

• Processing and storage of high or intermediate level waste containing plutonium, highly enriched uranium or uranium-233 material for which safeguards have been terminated

• Long-term plans for the State’s nuclear fuel cycle development (cover­ing a 10-year period).

Whereas Article 2 defines what is to be provided, Article 3 delineates when the information is to be provided, both initially and on a routine update basis.[56] Depending on the specific Article 2 provision, the relevant update needs to be transmitted (in accordance with Article 3) either quarterly, annually, as requested by the IAEA, or as agreed with the IAEA. There are the following important practical considerations a ‘newcomer’ State may want to keep in mind regarding the provision of information.

• Factors such as the site complexity, regulatory responsibilities, leasing arrangements that include tenants that may or may not be related to the nuclear fuel cycle (e. g., private companies), the temporary existence of construction tents, level of descriptive information to provide, could all add to the complications of preparing the requisite AP declaration. Early discussions with the IAEA, and perhaps other SSACs, are likely to make the process less daunting.

• The IAEA developed guidelines in 1997 to assist in the preparation and formatting of the AP declaration. Since then, the guidelines (IAEA, 2004) have been updated and reissued, and should be considered as an additional source of helpful information.

• It should not be considered unusual if the IAEA has a need for ampli­fication or clarification of information submitted by the State pursuant to the AP. If such an occasion arises, the responsible National Authority[57] will be informed accordingly, and as experience shows, often the issue can be addressed through timely communication between the State and IAEA.

• It is a relatively more serious safeguards matter when a question or inconsistency is brought to the attention of a State. In such cases, it is to the benefit of all parties to resolve the issue(s) in a timely manner through close consultation and good cooperation between the State and the IAEA.

• Computer software[58] to help States with the submission of their AP declarations is available from the IAEA.

Complementary access (CA) is a measure which complements the access rights in the relevant Safeguards Agreement by provisioning the right of the IAEA to go to certain additional locations in a State for specific reasons as provided for in the AP. Complementary access is not an inspection, nor is it a right for the IAEA to go anywhere in a State for any reason what­soever. Its implementation is exercised by the IAEA in accordance with the relevant articles of the AP.

With reference to the provisions of Articles 5 and 9 of the Model Additional Protocol (INFCIRC/540 (Corrected)) (IAEA, 1997a), the IAEA has a right to access all places on the declared sites of facilities and locations outside facilities, all other places where nuclear material is declared located, decommissioned facilities and LOFs, locations declared by the State where other nuclear fuel cycle-related activities are conducted, and other locations (under certain circumstances).[59] When a complementary access is to be performed by the IAEA, it must always be carried out in an objective and impartial manner. Normally, it is initiated via written corre­spondence from the IAEA to the State.[60] The advance notification to the State specifies the location(s) to be accessed, along with the reasons for access and the activities to be carried out during such access. The list of the authorized activities to be performed depends on the location to be accessed. Examples of such activities, as reflected in Article 6 of the Model AP, include visual observation; collection of environmental samples; use of radiation detection and measurement devices; examination of safeguards relevant production and shipping records; examination of records relevant to the quantities, origin and disposition of material; and/or placement of seals and other identifying and tamper-indicating devices specified in Subsidiary Arrangements.[61]

Experience shows that a complementary access can be conducted effi­ciently and effectively the more technically capable the National Authority representative is (regarding the use of IAEA authorized equipment, col­lection of environmental samples, and other safeguards measures permitted under the AP). At certain times, for reasons relating to the sensitivity of information,[62] a State seeks to manage access to selected equipment, tech­nology and processes. In such cases, the State may request ‘managed access’ provision in accordance with Article 7 of the protocol. These considerations are a normal part of the conduct of a complementary access, and the IAEA inspectors are trained to consult with the designated National Authority and the operator to find appropriate alternative methods or options to achieve the objectives of the complementary access.

Depending on the needs of the State concerned, the IAEA may be able to offer other services and technical assistance, such as AP-specific training or regional workshops on safeguards implementation. In addition, several countries (such as Australia, Japan and the United States) have in the past supported outreach programmes for developing countries, including spon­sorship of regional or international seminars and training workshops, which may serve to enhance a State’s technical capability and/or readiness for implementing the AP and its related safeguards commitments. Contact through the respective government mission to the IAEA or directly through the IAEA will often provide an understanding of such possibilities.

One benefit arising from the implementation of the AP is that integrated safeguards (IS) can be implemented in a State where the IAEA has been able to draw a broader safeguards conclusion for the State.[63] IS refers to an optimized combination of all safeguards measures available to the IAEA under the CSA and AP, to maximize effectiveness and efficiency within available resources.[64] With the increased assurances of the absence of unde­clared nuclear material and activities in the State as a whole, implementa­tion of IS takes into account a reduction in the traditional level of safeguards verification effort expended on less sensitive nuclear material (e. g., low enriched, natural and depleted uranium and irradiated fuel). For States with an expanded nuclear fuel cycle, this has been shown to have a significant impact on resource utilization (i. e., shifting the focus to nuclear facilities, activities and material with higher strategic value). The same benefits are available to countries embarking on an expanded nuclear power pro­gramme; therefore, incorporation of the AP as part of a country’s safe­guards obligation should be given due consideration, if it is not already in force.

Should a NNWS decide positively on the inclusion of the AP as part of its safeguards agreement with the IAEA, the IAEA should be consulted early for the provision of advice and support to place the protocol in force. During this process, the State will need to determine which National Authority should have the responsibility for assuring that the objectives of the AP are fully achieved. As part of its options, it may consider adding the AP-related responsibilities to those of its designated SSAC. It is not a requirement, but many countries find this beneficial to both the State and the IAEA. In any case, examples of the type of AP-related responsibilities given to the National Authority include:

• Coordination and preparation for the submittal of relevant AP declarations

• Verification of declarations for correctness and completeness

• Processing and transmittal of declarations to the IAEA

• Responding to IAEA requests for additional information or clarification

• Facilitating the conduct of complementary access

• Resolving any AP-related questions and inconsistencies.

Few new reactors were ordered after 1986; the number coming on line from the mid-1980s little more than matched retirements. Chernobyl and electric­ity market liberalization were generally viewed as the final nails in the coffin of nuclear power. It was inconceivable for many analysts that nuclear power could survive in the absence of ‘cost plus’ pricing in a competitive market. While the number of construction starts indeed suggested an early demise of the industry, it was not lack of construction but market pressures and competition that forced it to streamline and consolidate operations. In a deregulated environment, with the rate base eliminated, revenues are based solely on the difference between a plant’s operating and fuel (or short-run marginal) costs plus the remaining debt on yet to be depreciated assets and the market price of electricity.[88] Many analysts were of the opinion that the remaining debt on nuclear power plants would make them too expensive to compete with coal — and gas-fired generation. Economic rationale sug­gests, however, that an existing plant continues operating as long as reve­nues cover marginal operating cost irrespective of any debt as even small margins above short-run costs contribute to debt repayment and profits.

For a capital-intensive technology in a competitive market such as nuclear power, it is vital to put the assets to productive, i. e. revenue, generating use. The more kWh a plant generates, the lower its total production costs per kWh as fixed costs are distributed over more kWh. Until the early 1990s, the load factor (the percentage of time a plant generates full capacity elec­tricity to the grid) of the global fleet of nuclear power plants hovered around 65%. Competition forced nuclear operators to condense mainte­nance outages, reduce overhead costs through consolidation of different plants, and implement numerous other management measures. By 2005 the global load factor reached more than 80% (see Fig. 15.2) which allowed continued growth in nuclear generation, despite aggregate capacity expand­ing only 14% over the period (see Figs 15.3 and 15.4). The vastly improved utilization of existing capacities worldwide corresponds to a virtual con­struction of more than 30 1000 MW nuclear power plants.

Variable operating costs, essentially fuel costs, are a comparative advan­tage of nuclear power, especially in competitive markets and when plants are fully depreciated, thus making licence extension highly profitable for many nuclear operators. The reason is straightforward: it costs considerably more to build any type of new generation — fossil, nuclear or renewable — than to invest in the maintenance/replacement of some nuclear components

85

80

2700

2400

2100

1800

1500

and run a nuclear plant for an additional 20 years.[89] These investments usually also result in improved operating safety, power uprates and/or higher output (e. g. new turbines, more efficient steam generators), all of which further improve overall economics.

Another reason for the attractiveness of licence extension is public acceptance and greatly reduced licensing procedures compared with new build. As regards public acceptance, communities hosting nuclear power plants have had a positive decade-long experience living with the technol­ogy, i. e., a better comprehension of the associated benefits exceeding the risks.

The primary output of the SEA process is the Environmental Report, a document required by the SEA Directive which identifies the likely signifi­cant effects on the environment that would occur if the plan or programme were to be implemented (SEA Directive, 2001, Article 5(1)). Annex I of the SEA Directive sets out the minimum information that the Environmental Report should contain. Given that the SEA process is essentially a com­parison of the state of the natural and human environment with and without the plan or programme being implemented, the starting point of the Environmental Report is to identify the current state of the environment and how that area would evolve without implementation of the plan or programme (SEA Directive, 2001, Annex 1, paragraph (b)). The Environmental Report should also identify the broad environmental char­acteristics of the area likely to be affected, as well as the particular areas where impacts could be significant, such as biodiversity, population, human health, archaeological heritage and landscape (SEA Directive, 2001, Annex 1, paragraphs (c) and (f)).

Perhaps the most significant part of the Environmental Report, however, at least in terms of the ideological drive behind the SEA Directive, is the part which identifies the measures envisaged to ‘prevent, reduce and as fully as possible offset’ (SEA Directive, 2001, Annex 1, paragraph (g)) the sig­nificant adverse impact on the environment. Indeed, the SEA process would have very little worth if authorities were not obliged to consider ways to mitigate the serious environmental effects that have been identified by the process. These measures should be drawn up in light of current knowledge and methods of assessment and the contents and level of detail in the plan or programme so as to ensure that the local authority can identify mitiga­tion measures which would be commensurate with the nature and extent of the likely environmental effects (SEA Directive, 2001, Article 5(2)).

As well as identifying practical measures that would mitigate the envi­ronmental impact of the proposed plan or programme, the SEA Directive also requires the Environmental Report to identify, describe and evaluate the ‘reasonable alternatives taking into account the objectives and the geo­graphical scope of the plan or programme’ (SEA Directive, 2001, Article 5(1)). This requirement is designed to ensure that the authority gives serious consideration to the environmental impacts of the proposed activity and applies its mind to alternative plans or programmes (or variations on the existing plan or programme) what would have less serious consequences for the environment. On a practical level, the area of alternatives is often the most closely scrutinised by interested parties and, in the United Kingdom in particular, local authorities have been particularly cautious in their approach to identifying alternatives.

General requirements are based on the four principles described in Section 18.2. The principle concerning external factors affecting the plant obliges the applicant to investigate all possible natural phenomena and human- induced situations which may constitute a hazard to safe operation of the future NPP. For natural phenomena such studies require the analyses of prehistoric, historical and currently instrumented information and records related to the phenomena under study. For human-induced situations, they are of use in evaluating the hazards associated with hazardous industries and activities, such as the transport of explosive, flammable and toxic mate­rials, around the site under consideration and their foreseeable develop­ment with time.

The principle concerning the radiological impact on the public and the local environment requires the investigation of all potential radiological impacts on people and the environment that may be produced from the expected release of radioactive nuclides during normal operation and acci­dent conditions.

The principle concerning the feasibility of emergency plans requires the evaluation of the present and future distribution of the population in the region of interest, the present and foreseeable future uses of land and water and the radiological risks that the affected population may support in case of accident. It is also necessary to evaluate which site characteristics or concurrent natural phenomena may occur that may hinder the efficiency of the already established emergency plan. The Fukushima event has clearly demonstrated how the major emergency situation created by the earth­quake and resulting tsunami created a nuclear emergency inside a previous, much larger, naturally induced emergency.

The principle related to the ultimate heat sink provision requires the identification of the pathways internal to the plant by which decay heat can be transferred to the environment under heavily deteriorated conditions. Damping such decay heat to the atmosphere is recommended provided that such releases do not involve the concurrent release of radioactive nuclides.

The EUR document was developed by a number of European utilities, to establish a set of common voluntary requirements for the design of future LWR power plants in Europe. This document can also be applied to a wider, international market.

Some of the expected EUR application benefits are:

• Improved acceptance from the public and the authorities, achieved by using common technical solutions and common safety approaches

• Boosting nuclear energy competitiveness by controlling investment costs through the prescription of design standardisation and simplifica­tion, and by setting ambitious plant performance and maintenance cost reduction targets.

The EUR is structured into four volumes:

• Volume 1, ‘Main policies and objectives’, outlines the major objectives of the EUR organisation and the main policies laid down in the EUR document for future nuclear power plants, in aspects such as plant design, safety and licensing, standardisation, operational targets and economic objectives. It also summarises the most important require­ments of Volumes 2 and 4.

• Volume 2, ‘Generic nuclear island requirements’, includes all the generic requirements and European utility preferences for the NI, which are not related to any specific design. Requirements are organised by chapters according to specific topics, as follows: safety requirements; performance requirements; grid requirements; design basis; codes and standards; material-related requirements; functional requirements: components; functional requirements: systems; containment systems; instrumentation and control and man-machine interface; layout rules; design process and documentation; constructability; operation, maintenance and proce­dures; quality assurance (QA); decommissioning; probabilistic safety analysis (PSA) methodology; performance assessment methodology; and cost assessment information requirements.

• Volume 3, ‘Application of EUR to specific designs’, is divided into a number of subsets. Each subset is dedicated to a specific design which is of interest to the EUR utilities. The volume contains a description of a standard NI, a summary of the analysis of compliance as compared to EUR Volumes 1 and 2, and, where needed, design-dependent require­ments and preferences of the EUR utilities.

• Volume 4, ‘Power generation plant requirements’, outlines the generic requirements in relation to the power generation plant (i. e. the turbine island).

The differing roles of the operator and of the regulator with respect to safety need to be made clear. The IAEA’s Fundamental Safety Principles require that ‘the prime responsibility for safety must rest with the person or organization responsible for facilities and activities that give rise to radia­tion risk’ (IAEA, 2006c). That is, the licensee is responsible for safety, and the regulator is responsible for granting licenses and providing oversight of the operator’s activities with respect to safety. These responsibilities persist throughout the entire life cycle of an NPP and can span a period of several decades. The license specifically states that the licensee is responsible for the following:

• Establishing and maintaining the necessary competences

• Providing adequate training and information

• Establishing procedures and arrangements to maintain safety under all conditions

• Verifying appropriate design, and the adequate quality of facilities and activities and of their associated equipment

• Ensuring the safe control of all radioactive material that is used, pro­duced, stored or transported

• Ensuring the safe control of all radioactive waste that is generated.

On leadership and management for safety, Principle 3 of the Fundamental Safety Principles states that ‘Leadership in safety matters has to be demon­strated at the highest levels in an organization’. Therefore, the starting point for a licensee is senior management’s leadership of, and commitment to, safety through a clearly articulated safety vision that is communicated to every employee. Or, as the International Safety Group (INSAG) expresses it (INSAG, 2002):

Commitment to safety and to the strengthening of safety culture at the top of an organization is the first and vital ingredient in achieving excellent safety performance. This means that safety (and particularly nuclear safety) is put clearly and unequivocally in first place in requirements from the top of the organization, and there is absolute clarity about the organization’s safety philosophy.

The next step is to ensure that a safety culture, leadership and manage­ment systems and processes are all in place to ensure safety. These must be established early in the NPP project and certainly before the bidding process begins. For a new NPP operator, assistance from an experienced operator of a similarly designed NPP is likely to be essential for establishing these requirements. Once established, the licensee must communicate its safety policies on an ongoing basis to both staff and its suppliers. For example, bid specifications should clearly reflect the operator’s safety requirements. Also, the licensee should include formal presentations on the expected compliance of all stakeholders with the licensee’s safety vision, including contractors, suppliers, constructors, vendors and support groups.

The operator must also establish effective relationships with the regulator, even before the bid is specified. During the early stages of an NPP deploy­ment programme, there are many interfaces that need to be managed by the licensee, since the operator is at the centre of all the activities. The various interfaces typically include governments, regulators, the public, the media, the designer/vendor, construction companies, and manufacturers and suppliers. Notwithstanding this, the licensee and regulator must take the time to establish professional and comprehensive interactions to ensure that there is joint understanding of the licensing processes and requirements.

Nuclear research centres will give the scientific and technical support to nuclear development as well as promoting the research and development for current and foreseen future problem-solving and technological innova­tion. Additionally these organizations will facilitate the transfer of technol­ogy. Chapter 7 describes the needs and roles of such nuclear research centres.

The participation in international research and development projects, excellence networks and specialized forums, such as those identified in Section 6.5, is another important source of nuclear knowledge and interna­tional relationships.

Utilities

Utilities will have a crucial role to play in the development of the nuclear programme: site and technology selection, economic feasibility and

financing, project planning, licensing, construction, commissioning and operation of the future nuclear facilities.

During the preparation phase the overall manpower needs are relatively modest, mostly orientated towards directing, coordinating and registering data, but do involve a large number of organizations (including political decision makers). Although the manpower required is relatively low, they need to be highly qualified professionals. The relevant staff should prefer­ably have professional experience in the coordination and performance of complex interdisciplinary studies. The needs start to increase strongly when the commitments are made (letter of intent and contract) to build the plant. The involvement of a knowledgeable consultant is recommended.

ANENT is set up to promote, manage and preserve nuclear knowledge and to ensure the continued availability of talented and qualified human resources in the nuclear field in the Asian region and to enhance the quality of the resources for the sustainability of nuclear technology.

The objective of ANENT is to facilitate cooperation in education, related research and training in nuclear technology in the Asian region through:

• Sharing of information and materials on nuclear education and training

• Exchange of students, teachers and researchers

• Establishment of reference curricula and facilitating mutual recognition

of degrees

• Serving as a facilitator for communication between ANENT member organizations and other regional and global networks.

The essential functions of ANENT are to integrate available resources for education and training in synergy with existing IAEA and other mecha­nisms, to create public awareness about the benefits of nuclear technology and its applications, to attract talented youth in view of alternative compet­ing career options, to encourage senior nuclear professionals to share their experience and knowledge with the young generation, and to use informa­tion technology, in particular web-based education and training, to the maximum possible extent.

Some radioactive waste will be generated from NPP operation in the form of liquid effluents, solid waste and gaseous effluents. The liquid effluents with low levels of radioactivity are treated using appropriate processes and recycled as far as possible, but some liquid effluents will have to be dis­charged to the environment. Such discharges are generally done using the dilute and disperse principle. The effluents are diluted, for example by the large quantities of condenser cooling water outlet from the NPP, and then dispersed in large water bodies like a lake, river or sea near the NPP site. Solid radioactive waste is generated from plant operation in the form of replaced components or their parts, piping sections, used filters, exhausted ion exchange resins, radioactively contaminated personnel protective wear like coveralls, gloves and caps and materials like mops used for decontami­nation of floors and other surfaces. The solid radioactive waste is stored in near-surface disposal facilities after volume reduction and packaging where feasible. Such facilities may be co-located with the NPP or they could be centralized facilities located elsewhere and may store radioactive waste from several installations. Some solid wastes such as ion exchange resins may require special treatment before disposal, such as fixation of radioac­tivity in the resin in cement or polymer matrix to prevent its leach-out during extended storage. Facilities for such special treatment have to be built as part of the NPP complex. Radioactive gaseous effluents are generated by neutron activation of air and suspended particulates and by pick-up of radioactivity by reactor ventilation air during its passage through radioactively contaminated areas. The ventilation exhaust air from the reactor building and other plant buildings having a potential for giving rise to airborne radioactivity is filtered through high-efficiency particulate filters for removal of particulate activity and, if necessary, through special filters like those made of activated charcoal for trapping radioactive iodine. It is then released through a tall stack into the atmosphere for dilution and dispersal.

It can be seen that radioactive waste management at NPP sites is an ongoing activity that requires special expertise. This function is important as it is to be ensured that radioactive waste disposal to the environment must be within the prescribed limits. Further, even within the specification limits, it should be kept as low as reasonably achievable to minimize adverse impact on the environment in the long term. This objective can be achieved only through having a dedicated radioactive waste management team with high technical competence. Ongoing research and development at the tech­nical support organizations is also necessary towards developing improved processes for recycling of liquid waste and reducing waste volumes to the maximum extent possible.

7.7.6 Spent fuel management

Spent fuel removed from the reactor core has to be properly and safely stored for several years before it can be shipped out for reprocessing, final disposal or further storage at a different site. Spent fuel is stored under water in the spent fuel storage pool in fuel storage racks that have inbuilt high neutron-absorbing materials to ensure sufficient subcriticality. The pool water has to be circulated, cooled and purified to remove the decay heat transferred from the stored fuel to pool water and to maintain its chemistry parameters to minimize corrosion of the fuel cladding. For trans­portation of spent fuel from the NPP site, specially designed shielded casks are used and transportation is done after the decay heat in the fuel has come down to a level when natural convection cooling by surrounding air is sufficient to keep the fuel and fuel cladding temperature within specified limits.

If the storage capacity in the pool becomes insufficient due to inability to ship out the fuel for any reason, timely action is necessary for construc­tion of away-from-reactor storage pools to augment the storage capacity. The away-from-reactor pools have to be built and operated in the same way as the storage pool at the reactor site. It is also possible to store spent fuel in dry storage casks or dry storage facilities after it has been cooled for a sufficiently long period. Such casks and facilities may have to store spent fuel for a fairly long time till the final disposition of the fuel is decided. Accordingly they have to be kept under proper surveillance by periodic checks on fuel clad integrity and structural integrity of the casks and the facilities. Expertise in spent fuel management over extended periods of time that can run into several decades has to be acquired by the operating organization. The technical support organizations and the regulatory body also need to develop adequate technical competence in this field.

This section provides descriptions of the technology options currently avail­able for newcomer countries, in particular evolutionary reactor designs, as these are the most likely candidate technologies for most countries’ first nuclear power plant, particularly in the near to middle term. For complete­ness, however, a brief discussion examining future trends for the develop­ment of nuclear reactors in the long term has also been included.

9.1.1 Evolutionary reactor designs

As described above, evolutionary designs achieve improvements over exist­ing designs through small to moderate modifications, with a strong emphasis on maintaining design proveness to minimize technological risks. Not sur­prisingly, most of these are water-cooled reactors, as this type of design is the one where the nuclear community has more lessons learned and expertise.

The following designs, which have been ordered alphabetically herein, are those in a more advanced stage of development and would presumably be available for near-term deployment. In some cases, they have even been built or are in the process of being built somewhere in the world, and this will be indicated. The detailed technical data for all these designs can be found in IAEA (2010).

ABWR

The Advanced Boiling Water Reactor (ABWR), which is available from two competing vendors (GE-Hitachi and Toshiba, Fig. 9.3), combines the

best BWR design features from Europe, Japan and USA. The ABWR was developed in direct response to the EPRI Utility Requirements Document (URd) (EPRI, 1995, 1999), it is licensed in the USA, Japan and Taiwan (China) and it is the first evolutionary reactor design to operate commer­cially. There are currently four ABWRs in operation in Japan (Kashiwazaki — Kariwa 6 and 7, Hamaoka-5 and Shika-2), two in construction in Taiwan, China, and several more planned in Japan and the USA. In this sense, there is a proven capital and operation and maintenance cost structure associated with this design. The ABWR was designed with a shorter construction schedule in mind, by taking advantage of existing prefabricated construc­tion experience and applying it into a modularized design. Although exist­ing ABWRs are 1370 MWe, future ones are expected to be 1500 MWe as the reactor core has enough margins for these uprates. The ABWR has fully digital I&C and has adopted reactor internal pumps that eliminate the need for the large external recirculation coolant loops that involved penetrations below the top of the core elevation, thus making it possible to maintain core coverage during a postulated loss-of-coolant accident. This design also includes the capability to mitigate severe accidents and to reduce off-site consequences of accidents. The ABWR containment vessel is made of rein­forced concrete with an internal steel liner.