Environmental Impact from Depletion of Resources (Sustainability Assessment)

INPRO basic principle (BP) in the area of environmental impact by depletion of resources – The NES shall be capable of contributing to the energy needs in the twenty-first century while making efficient use of non-renewable resources.

Introduction

Objective

This volume of the updated INPRO manual provides guidance to the assessor of an NES (or a facility thereof) that is to be installed, describing how to apply the INPRO methodology in the area of environmental impact from depletion of resources. The INPRO assessment should enable either the confirmation of adequate environmental performance by the NES, i.e. fulfilment of all INPRO methodology environmental CR, or the identification of gaps (non-compliance with the INPRO methodology CR) requiring corrective actions (including research, development and demonstration (RD&D)) to achieve long term sustainability of the NES assessed.
The INPRO assessor (or team of assessors) is assumed to be knowledgeable in the area of environmental impact from depletion of resources and/or may be using the support of qualified national or international organizations (e.g. the IAEA) with relevant experience.
Two general types of INPRO assessors can be distinguished: a designer (supplier or developer) of nuclear technology, i.e. a nuclear technology holder, and a (potential) user of such technology.
The role of the latter type of assessor, i.e. a technology user, is primarily to check, in a simple manner, whether the designer (supplier) has appropriately taken into account the resource aspects in their design as defined by the INPRO methodology. A technology user is assumed, in order to minimize their risk, to be primarily interested in proven technology to be installed in their country.
A designer (developer) performing an INPRO assessment can also use this current publication to check whether the (innovative) design under development meets the INPRO methodology requirements, but can additionally initiate modifications during early design stages, if necessary, to improve the performance of the design.
An assessor in a country embarking on a nuclear power programme could use the INPRO methodology in a so called graded approach, depending on the stage of the programme (see overview of the INPRO methodology).
Guidance provided here, describing good practices, represents expert opinion but does not constitute recommendations made on the basis of a consensus of Member States.

Scope

Environmental impact from an NES involves two large groups of factors. The first group comprises radiological, chemical, thermal and other stressors which NESs release into environment. This group also includes water intake because this factor can be important for biota even when this water is returned to the environment in a clean form (e.g. as steam from NPP cooling towers). All these factors are considered in the INPRO methodology manual on environmental impact of stressors.
The second group of factors impacting the environment comprises the consumption of non-renewable resources including both fissile/fertile materials necessary to produce nuclear fuel and other materials (e.g. zirconium). All these factors and consumption of electricity necessary to construct, operate and occasionally decommission NES installations are considered in this updated INPRO methodology manual on environmental impact from depletion of resources.

Structure

In Section 2, general features of an environmental assessment on the impact of depletion of resources and an overview of information that must be available to an INPRO assessor to perform assessment are presented.
In Section 3, the background of the INPRO methodology BP for environmental impact from depletion of resources, and the corresponding URs and CR, consisting of INs and ALs, are presented. At the CR level, guidance is provided on how to determine the value of the IN and AL.
Appendix I summarizes information on global demand and supply of fissile and fertile materials. Appendix II presents information on global demand and supply of non-renewable materials (other than fissile and fertile materials).
Appendix III summarizes relevant results of the INPRO collaborative project on Global Architectures of Innovative Nuclear Energy Systems with Thermal and Fast Reactors, Including a Closed Fuel Cycle (GAINS), and provides references to some other studies that reflect upon uranium supply and demand in particular global NES evolution scenarios.
Appendix IV presents the results of an evaluation of the mass balance of an NES focusing on the front end of the fuel cycle. The tool used for the evaluation is the NESA Economic Support Tool (NEST) described in the INPRO methodology manual on economics (NESA stands for nuclear energy system assessment).
Table 1 provides an overview of the BP, URs and CR in the INPRO methodology area of environmental impact from depletion of resources

Table 1. Overview of basic principle, user requirements and criteria in the INPRO methodology area of environmental impact by depletion of resources

INPRO basic principle the area of environmental impact by depletion of resources (availability of resources): A nuclear energy system (NES) shall be capable of contributing to the energy needs in the twenty-first century while making efficient use of non-renewable resources*
INPRO user requirements	Criteria	Indicator (IN) and Acceptance Limit (AL)
UR1: Consistency with resource availability: The NES should be able to contribute to the world’s energy needs during the twenty-first century without running out of fissile/fertile material and other non-renewable materials, with account taken of reasonably expected uses of these materials external to the NES. In addition, the NES should make efficient use of non-renewable resources	CR1.1: Fissile/fertile material	IN1.1: Quantity, Fj(t), of fissile/fertile material type j available for use in the NES at time t
		AL1.1: Fj(t) > Dj(t), quantity available for NES, Fj(t), should be bigger than quantity needed, Dj(t), for any t < 100 years
	CR1.2: Non-renewable materials	IN1.2: Quantity, Qi(t), of material type i available for use in the NES at time t
		AL1.2: Qj(t) > Dj(t), quantity available for NES, Qj(t), should be bigger than quantity needed, Dj(t), for any t < 100 years
	CR1.3: Power supply to NES	IN1.3: P(t) = power available (from both internal and external sources) for use in the NES at time t
		AL1.3: P(t) ≥ PNES(t), for any t < 100 years, where PNES(t) is the power required by the NES at time t
	CR1.4: End use of uranium	IN1.4: Ueu = end use (net) energy (GW·h) delivered by the NES per tonne of uranium mined
		AL1.4: Ueu > U0; U0 = maximum achievable end use for an existing NES** with a once through (open) fuel cycle
	CR1.5: End use of thorium	IN1.5: Theu = end use (net) energy (GW·h) delivered by the NES per tonne of thorium mined
		AL1.5: Theu > Th0; Th0 = maximum achievable end use for a current operating thorium cycle
	CR1.6: End use of non-renewable resources	IN1.6: Ci = end use (net) energy delivered by the NES per tonne of limited non-renewable resource i consumed
		AL1.6: Ci > C0; C0 to be determined on a case specific basis
UR2: Adequate net energy output: The energy output of the NES should exceed the energy required to implement, operate and decommission the NES within an acceptably short period	CR2.1: Amortization time	IN2.1: TEQ = time required to match the total energy input into the NES with energy output (years)
		AL2.1: TEQ << TL; TL = intended lifetime of NES

* - Guidance provided here, describing good practices, represents expert opinion but does not constitute recommendations made on the basis of a consensus of Member States.
** - In the updated INPRO methodology, ‘existing NES’ means an ‘NES of latest design operating in 2013’.

Concept of sustainable development and its relationship with the area of environmental impact from depletion of resources of the INPRO methodology

The United Nations World Commission on Environment and Development Report (often known as the Brundtland Report), entitled Our Common Future, defines sustainable development as: “development that meets the needs of the present without compromising the ability of future generations to meet their own needs” (see chapter 2, paragraph 1). Moreover, this definition contains within it two key concepts:

• “the concept of ‘needs’, in particular the essential needs of the world’s poor, to which overriding priority should be given; and
• the idea of limitations imposed by the state of technology and social organization on the environment’s ability to meet present and future needs.”

This simple definition of sustainable development suggests a three part test for any approach to sustainability and sustainable development: (i) current development should be fit for the purpose of meeting current needs with minimized environmental impacts and acceptable economics; (ii) current RD&D programmes should establish and maintain trends that lead to technological and institutional developments that serve as a platform for future generations to meet their needs; and (iii) the approach to meeting current needs should not compromise the ability of future generations to meet their needs.
At first reading, this definition may appear obvious, but when considering the complexities of implemented nuclear energy technology and systems, plus their many supporting institutions, meeting the three part test is not always straightforward because many approaches only meet one or perhaps two parts of the test in a given area, and may fail on the others.

The Brundtland Report overview (para. 61) of the topic of nuclear energy summarized that:

“After almost four decades of immense technological effort, nuclear energy has become widely used. During this period, however, the nature of its costs, risks, and benefits have become more evident and the subject of sharp controversy. Different countries world-wide take up different positions on the use of nuclear energy. The discussion in the Commission also reflected these different views and positions. Yet all agreed that the generation of nuclear power is only justifiable if there are solid solutions to the unsolved problems to which it gives rise. The highest priority should be accorded to research and development on environmentally sound and ecologically viable alternatives, as well as on means of increasing the safety of nuclear energy.”

The Brundtland Report presented its comments on nuclear energy in chapter 7, section III. In the area of nuclear energy, the focus of sustainability and sustainable development is on solving certain well known problems (referred to here as ‘key issues’) of institutional and technological significance. Sustainable development implies progress and solutions in the key issue areas. Seven key issues are discussed (in this order):
(a) Proliferation risks;
(b) Economics;
(c) Health and environment risks;
(d) Nuclear accident risks;
(e) Radioactive waste disposal;
(f) Sufficiency of national and international institutions (with particular emphasis on intergenerational and transnational responsibilities);
(g) Public acceptability.
The INPRO methodology for the self-assessment of sustainability and sustainable development of a NES is based on the broad philosophical outlines of the Brundtland Report’s concept of sustainable development described above. Twenty-eight years have passed since the publication of the Brundtland Report, and 14 years have passed since the initial consultancies on development of the INPRO methodology in 2001. In the interim period of time, significant historical events have starkly highlighted certain key issues. However, the key issues for sustainable development of NESs have remained essentially unchanged over nearly three decades.
By far the most notable events in the period, which have a direct impact on nuclear energy sustainability, are related to non-proliferation, nuclear security, cost escalation of new construction and, most notably, the accident at the Fukushima Daiichi nuclear power plant in 2011. The Fukushima Daiichi accident further clarified that nuclear safety is an issue of paramount importance for sustainability and that external hazards, associated with a particular site, could be responsible for a dramatic common cause failure involving multiple reactor units.
In each INPRO methodology manual, a key issue of NES sustainable development is examined. The structure of the methodology is a hierarchy of INPRO BPs, URs and CR measuring whether the UR has been achieved. Under each BP, the CR include measures that take into consideration the three part Brundtland Report’s sustainable development test.
This INPRO manual focuses on the key issue of environmental impact through depletion of natural resources associated with NES development and deployment. The Brundtland Report did not specifically identify depletion of resources as a key issue in 1987. There are several reasons why these issues might have been omitted at the time, which still exist today. These reasons are described below.
In a broad and general sense, NESs are frugal with respect to the use of natural resources when compared to available dispatchable, baseload non-NESs. For example, it is unlikely that significant and sustainable pressure will come to bear on natural uranium fuel resources until the second half of the current century or well beyond that, depending on global nuclear energy growth and further discoveries of economically recoverable uranium resources. When uranium fuel becomes sufficiently expensive, closed fuel cycles can produce many thousands of years of nuclear fuel from existing fertile material resources. As the nuclear fuel cost is very low, taken as a fraction of the nuclear electricity cost, significantly more expensive nuclear fuel is likely to be acceptable, depending upon how a particular nuclear market is structured.
The more complex sustainability questions in the area of resource depletion pertain to use of other mineral resources that are rarer than nuclear fuels (e.g. critical minor constituents in metal alloys and other materials that are particular to nuclear energy technology). However, if a country decides that its NES should depend wholly upon its own mineral resources, rather than the international market, in some cases, this may also imply more severe limits to nuclear fuel sustainability. Questions about when and how diversification from a uranium fuel economy should expand to include a growing share of other nuclear fuels are more associated with development of roadmaps for reactor and fuel cycle technology development and deployment than they are with ultimate resource depletion. Even so, that progress is being made (or is planned) to achieve more effective fuel utilization is important, particularly for time periods extending well into the second half of this century. Essentially, indefinite and irretrievable direct geological disposal of once through uranium and thorium fuels may imply an unsustainable NES in the longer term. It also may also damage future nuclear fuel resource economics to a degree that it impugns nuclear energy as an option available to future generations, thus failing a key Brundtland Report test of sustainability.
This INPRO manual tests whether or not an NES is sustainable with respect to fissile/fertile and non-renewable material resources within a period of a century. It also tests whether or not greater net end use energy is being (or planned to be) produced from mined uranium and thorium than the maximum achievable under current open fuel cycles. Taken together, these measures directly address the question of whether NESs, implemented to meet current needs, are having minimum intergenerational impact from the perspective of natural resource depletion, thus satisfying the three part Brundtland Report sustainable development test.

General features and necessary INPUT for an assessment

This section provides some general background information on environmental issues, particularly on the environmental impact from depletion of resources caused by an NES. The necessary input and its sources for an assessment of an NES in the INPRO methodology area of environmental impact from depletion of resources are also defined.

Concept of sustainable development

The concept of sustainability can be considered from several related, but different, points of view: social, economic, environmental and institutional. This publication deals with the environmental dimension of sustainability, by considering issues related to depletion of natural resources.
Protection of the environment is a major consideration in the processes for approving industrial activities in many countries. The level of international societal concern for the environment is clearly indicated in publications reflecting international consensus, notably the Brundtland Report, the Rio Declaration on sustainable development and the Joint Safety Convention of the IAEA.
The common basic idea in these publications is that the present generation should not compromise the ability of future generations to fulfil their needs and should leave them with a healthy environment. Nuclear power should support sustainable development by providing much needed energy with relatively low burdens on the atmosphere, water, land and resource use. Efficient and effective use of resources will be necessary. Moreover, improvement of the technology should include improvement of its environmental aspects to a degree that is consistent with importance to society and with the potential environmental performance of competing technologies.

Interfaces of a nuclear energy system with the environment

The different components or facilities of a complete NES are presented in Fig. 1, starting with mining and processing, through to the final disposal of nuclear waste.

FIG. 1. Interfaces of a nuclear energy system with the environment.

An NES has several interfaces with the environment and other industries. From the environment, non-renewable resources such as fissile and fertile materials, e.g. uranium and thorium (orange arrow in Fig. 1), are removed and used in the NES together with other materials such as zirconium (bright yellow arrow in Fig. 1). On the other hand, the NES produces some stressors, e.g. release of radioactive nuclides, that have an adverse impact on the environment (pale yellow arrow in Fig. 1).
In addition to these environmental effects, an NES is exchanging with other industries the energy and industrial materials required for the installation, operation and finally decommissioning of the nuclear facilities (blue arrow in Fig. 1).
Ideally, an environmental impact assessment of an NES takes all these interfaces into account during the lifetime of the system.

Specification of the nuclear energy system

A prerequisite for an INPRO assessment is the specification of the NES (see overview of the INPRO methodology) to be assessed. The NES is to be defined by the INPRO assessor.
For an environmental assessment, in principle, the following aspects should be covered in the specification of the NES:

• The complete NES should be considered, covering the entire front end of the fuel cycle, the energy conversion unit (reactor) and the entire back end comprising waste repositories. For all nuclear facilities, the complete lifetime should be covered, i.e. construction, operation and decommissioning.
• If necessary, environmental burdens may be divided into national (or regional) burdens and those occurring outside the country (or regional) borders, if such information would be required by stakeholders.

Thus, by meeting the above defined requirements, the general underlying principle of assessing the entirety of the environmental impacts would not be violated.
However, in general, cut-offs, i.e. selection of specific facilities of an NES, will be required in an INPRO assessment. Such an approach is recommended for nuclear technology users and specifically in the case that a country is embarking on a nuclear power programme, i.e. the INPRO environmental assessment in such a country should cover only the first nuclear power plant and related waste management facilities. A nuclear technology developer may focus the environmental assessment (analysis) on their design of a nuclear facility under development.

Information on demand and supply of resources

To assess criterion CR1.1 of UR1, several generic studies are available that define the global demand and the availability of primary (and secondary, if a global market exists for it) supply of natural uranium (and other fissile materials) needed for nuclear facilities within the next 100 years. These studies, presented in Appendices I–IV, cover different development rates of demand and different fuel cycles.
To assess criterion CR1.2 of UR1, the results of a generic study for global demand and supply of other key materials in an NES are needed to complete an INPRO assessment. A recently performed generic study on global supply and demand of non-renewable materials is summarized in Appendix II, and could be used as reference in the assessment.
To assess criterion CR1.3 of UR1, information about the power needed to construct, operate and decommission a typical nuclear power plant currently operating is available, but for the NES assessed, this information is to be provided by the (potential) supplier.
To assess criterion CR1.4 and criterion CR1.5 of UR1, the net energy delivered by the NES assessed per tonne of uranium and thorium used is to be calculated. For uranium, this value can be determined by the INPRO assessor using a simplified tool, if the assessor has access to the specific characteristics of the assessed NES, such as the thermal efficiency and core average burnup of the nuclear power plant to be installed in the country.
To assess criterion CR1.6 of UR1, the end use of key materials (other than fissile and fertile materials) needed in the NES assessed and in the current NES is to be determined. For such a study, close cooperation between the assessor and the (potential) supplier is necessary. For some key materials, the results of generic studies on a current NES are available.
To assess criterion CR2.1 of UR2, a reference study is available that defines the energy payback time (EPBT) for a typical currently operating NES.

Other sources of INPUT

A comprehensive INPRO assessment of the planned NES in the Republic of Belarus has been performed between 2009 and 2011, and is documented in Ref..

INPRO Basic Principle, User Requirement and Criteria

This section presents the BP, the URs and the CR in the INPRO methodology area of environmental impact caused from depletion of resources.

INPRO Basic Principle: availability of resources

INPRO basic principle: The NES shall be capable of contributing to the energy needs in the twenty-first century while making efficient use of non-renewable resources.
To be environmentally acceptable, the NES assessed must be sustainable and not run out of important resources part way through its intended lifetime. These resources include fissile/fertile materials, water (when supplies are limited or quality is under stress) and other critical materials. The NES should also use them at least as efficiently as acceptable alternatives, both nuclear and non-nuclear. Even in the absence of a viable alternative, the best use possible is to be made of non-renewable resources.
Sustainability of an NES requires primarily that it fits its purpose. This has different aspects, which are addressed separately within the different INPRO methodology areas (e.g. economics, safety). All aspects should be considered, and the designer and operator of the system should strive to achieve optimal conditions with minimal effects on the environment, for which compromises across the areas may be necessary. Thus, the INPRO methodology requires a holistic approach, i.e. the whole NES should be considered in all areas, and all material flows in and out of the NES should be accounted for, including resources taken from, as well as stressors emitted to, the environment.
The INPRO methodology has defined two URs, UR1 and UR2, for the BP.

User requirement UR1: consistency with resource availability

User requirement UR1: The NES should be able to contribute to the world’s energy needs during the twenty-first century without running out of fissile/fertile material and other non-renewable materials, with account taken of reasonably expected uses of these materials external to the NES. In addition, the NES should make efficient use of non-renewable resources.
UR1 addresses continuous availability and consumption of non-renewable resources. Primarily, it should be demonstrated that the NES assessed will operate throughout the twenty-first century without incurring fuel shortages and lack of strategic materials. The time horizon of about 100 years was chosen in the INPRO methodology based on the consideration that beyond this period, uncertainties become too large in any evaluation result. To demonstrate that this UR is met, careful consideration should be given to the implications of available resources with appropriate choice of the boundary of the NES assessed (see Fig. 1). The availability and consumption of resources generally require a global, rather than an individual national or regional, evaluation. In addition, resources considered, especially those of fissile/fertile materials, need to include estimated resources beyond those currently fully proven. When addressing unconventional sources (e.g. uranium coextraction with phosphates or extraction of uranium from sea water (see Appendix I for more information)), the assessor should bear in mind that such unconventional resources of fissile/fertile materials may have implications not only on the environment, but also on the costs of nuclear fuel.
Global, regional and national energy demand/supply scenarios
To address UR1, it needs, in principle, to be demonstrated that the NES demand for non-renewable resources can be supplied at any time that the NES is operated during the twenty-first century, considering the entire lifetime (commissioning, operation and decommissioning) of all its facilities. As a global market exists and is likely to continue existing for all NES related non-renewable resources, such a demonstration generally requires a global analysis that is beyond the reasonably expected capability of any individual country performing an NES assessment. The way forwards here may be twofold.
One way is to borrow from the results of the recently completed international studies on global availability of non-renewable resources; in order to facilitate this method, Appendices I–IV are included in the current publication, where the main results of such studies and the approaches used are highlighted and summarized, complete with a list of references to full reports on these studies.
On the other hand, if a country performing the NES assessment has great plans for its nuclear energy programme and foresees it could eventually become a major player in global nuclear energy markets, then it makes sense to consider joining efforts with other countries to perform an updated global resource availability assessment. Such assessments are being periodically undertaken under the aegis of renowned international organizations, and one option to do so is to join the activities of the IAEA/INPRO task ‘Global scenarios’.
Notwithstanding the existence of a global market for NES related non-renewable resources, national assessment also makes sense once the country considers ensuring that its national nuclear power programme benefits from its own domestic resources. Assessment of this kind will be useful for understanding the national resource base and national economy potential, if only in the medium and long terms, but it will only partially support the assessment against the UR1 requirement.
Regional assessment could be recommended in the case of existing or foreseen long term partnerships with particular neighbouring or non-neighbouring countries with which good relations and cooperation in the nuclear energy field exist. Such an assessment could foster further cooperation, potentially resulting in a sustainable regional NES; however, as in the case of a national assessment, it would only partially support the assessment against UR1.
In both national and regional assessments, the missing ‘rest of the world’ information could be retrieved from the already completed resource availability studies such as those presented in the appendices to this publication. Summarized below are the factors that are important for non-renewable resource availability assessment of relevance to UR1.
For an INPRO assessment of the environmental impact from depletion of resources, the global and national (regional) scenarios of nuclear capacity growth first need to be specified, including data on time dependent capacity additions and corresponding reactor types. To obtain an idea of possible global scenarios, the information presented in Refs may be useful. These studies provide a range of plausible (and even some idealistic) global nuclear energy capacity increases, and following several scenarios within the range may aid in understanding how the existing large uncertainties could affect the results of a UR1 INPRO assessment.
Also useful could be an analytical framework for material flow analyses developed within the collaborative project GAINS. This framework, presented in Ref., includes internationally verified data for many existing and future reactors, descriptions of closed fuel cycles, storylines and scenarios of global nuclear energy development up to the end of this century, results of cross-verification and recommendations on the use of material flow analysis codes, and other relevant information.
The INPRO methodology defines six CR (CR1.1–CR1.6) for UR1, as shown in Table 1.

Criterion CR1.1: Fissile/fertile material

Indicator IN1.1: Fj(t), quantity of fissile/fertile material of type j available for use in the NES at time t.
Acceptance limit AL1.1: Fj(t) > Dj(t), quantity available for NES, Fj(t), should be bigger than quantity needed, Dj(t), for any t < 100 years.

Types of resources of fissile and fertile materials

In order for an NES to operate successfully, i.e. to contribute to satisfying the world’s energy needs during the twenty-first century without running out of resources, UR1 must be primarily applied to fissile/fertile materials, i.e. compliance must be demonstrated with CR1.1, confirming that the quantity of fissile/fertile material type j available at time t will always be more than needed in the NES assessed at any time t during a period of 100 years.
A fissile material is one that is capable of sustaining a chain reaction of nuclear fission. The principal fissile materials are ²³⁵U (0.7% of naturally occurring uranium), ²³⁹Pu, ²⁴¹Pu and ²³³U, with the last three being artificially produced from the fertile materials ²³⁸U and ²³²Th. A fertile material, not itself capable of undergoing fission by neutrons, is one that decays into fissile material after neutron absorption. Fertile materials are ²³²Th, which can be converted into fissionable ²³³U, and ²³⁸U, which can be converted into fissionable ²³⁹Pu.
In general, two kinds of sources of fissile/fertile materials are distinguished: primary resources and secondary supply; the latter is also sometimes called the secondary source. Estimations of the availability of such resources can be found in a diverse set of publications by national and international organizations. Table 2 gives an overview of types of resources of fissile and fertile materials, and the references from which information can be retrieved.

Table 2. Overview of basic principle, user requirements and criteria in the INPRO methodology area of environmental impact by depletion of resources

Resources of fissile/fertile materials	References
Primary resources*
Natural uranium Natural thorium	Appendix I; Refs
Secondary supply
Depleted uranium (including its re-enrichment) Natural uranium inventory (governmental and commercial) drawdown Highly enriched uranium available for down blending (with depleted uranium essentially)	Appendix I; Ref.
Reprocessed uranium
Plutonium from reprocessing of civil spent uranium fuel Plutonium from the surplus military Pu stock Spent nuclear fuel available for reprocessing Transuranium elements in spent fuel retrievable for later use Separated minor actinides (Np, Cm and Am) stock Uranium-238 produced by reprocessing of Th fuel	National data**; Appendix I

* - These primary resources are still to be mined, i.e. they are not yet recovered from their natural environment, but due account is taken of the losses that mining would entail, i.e. these resources represent the net available resources that would be available after mining.
** - ‘National data’ indicates that no international referenced data are available in the public domain.
The availability of fissile/fertile materials should be considered according to different scales. As has already been mentioned, because the primary resources of uranium and thorium are available via a global market, the availability of primary resources needs to be considered in an INPRO assessment on a global scale. However, most of the secondary supply is available on a national (or regional) scale only, and can, therefore, be considered only by individual Member States in national or regional assessments.
Of the secondary uranium sources, depleted uranium produced at enrichment facilities, natural uranium withdrawn from inventories held by utilities and governments, and separated irradiated uranium (reprocessed uranium (REPU)) produced in reprocessing facilities could be used in (partly) closed nuclear fuel cycles and are also available on a global market because of the ease of transportation of these materials.
Transuranics (TRUs), i.e. plutonium, and minor actinides (MAs) resulting from reprocessing of civil spent uranium based fuel, are today part of national NESs with a (partly) closed nuclear fuel cycle and are currently absent from any global market mechanism trading these materials. The possible transfer of such TRUs from outside into an NES has been taken into account in studies presented in Appendices II and III, looking very far into the future, i.e. covering a time period until the end of the century. The same applies to the spent fuel amount and the TRUs contained in that spent fuel.
Plutonium originating from surplus military stocks should be considered on a national scale, because of the limited availability of this resource based on bilateral contracts between certain Member States.
Thorium resources
There is still less known about the primary thorium resources compared to the uranium resources. Large thorium resources are found in Australia, Brazil, Canada, China, Egypt, India, Norway, Russian Federation, South Africa, Turkey, United States of America (USA) and the Bolivarian Republic of Venezuela. Existing estimates of thorium resources total more than 6.5 Mt Th. These estimates are considered conservative because the historically weak demand has limited thorium exploration.
Classification of primary resources according to their recoverability defined by the IAEA and the OECD Nuclear Energy Agency (OECD/NEA) is described in Appendix I.
Secondary uranium supply
It is generally expected that the role of global secondary uranium supply will diminish during the coming decades due to drawdown of natural uranium inventories and the limited availability of military plutonium to be used in a limited number of reactors. Currently, the main global secondary supply is based on down blending of highly enriched uranium (HEU), and in the medium term, re-enrichment of depleted uranium as long as the economic balance of this option versus virgin uranium mining remains attractive.
In case the NES assessed by an INPRO assessor might not be installed before the year 2030 or later, the impact of global secondary supply is likely to be limited. Therefore, in such a case, the INPRO assessment may not need to take into account the global secondary supply, except for, possibly, the re-enrichment of depleted uranium, depending on its economic viability and the availability of enrichment capacity. Above all, if nuclear energy is to remain an option for the longer term, renewal of exploration and opening of new mineable uranium resources have to be relaunched in order to supply most and soon all of the uranium requirements for the global nuclear reactor fleet.

Balance of demand and available resources of fissile/fertile materials

Criterion CR1.1 demands two considerations:

• Knowledge of the amount of fissile/fertile material available for the NES assessed. These available resources consist of global and national (regional) resources of fissile and fertile materials, including plutonium in the case of a closed fuel cycle, or 233U in a fuel cycle using thorium as the fertile material.
• Knowledge of the amount of fissile/fertile material needed in the NES assessed. This demand for resources consists of fissile/fertile materials entering the NES, i.e. being supplied as reload fuel.

Estimation of available amount of global primary uranium resources
Appendix I presents the status of available fissile and fertile materials based on the ‘Red Book’, a joint report by the IAEA and OECD/NEA. As of 2011, there were ~12 × 10⁶ tonnes of natural uranium (tU) available in the cost category of <US $130, and ~18 × 10⁶ tU in the cost category of <US $260, defined as conventional resources. In addition to these conventional resources, there are estimated resources of the same order of magnitude defined as unconventional uranium resources that include uranium found in phosphates and black shale, with estimated prices slightly above the ones for conventional resources.
Uranium contained in sea water would be available in an amount greater than 4 × 109 tU, although at a significantly higher price. Appendix I emphasizes the fact that the uranium supply is based on a global free market that reacts appropriately to higher prices because of expected shortages by increased exploration and production capacity.
Long term perspective of global demand for primary resources of fissile and fertile materials
In Appendix I, which contains a summary of the 2011 edition of the Red Book, the demand for natural uranium for the global NES up to 2035 is estimated. In Appendix III, a summary of a more recent comprehensive study regarding global demand for primary fissile/fertile resources until the end of the twenty-first century is presented, which takes into account several parameters such as different types of fuel cycles, different types of reactors, different rates of installation of nuclear facilities, etc. This generic study and the analytical framework developed within it can be used as a basis for all INPRO assessments of the environmental impact from depletion of resources.
Estimation of available amount of national (regional) primary resources of fissile and fertile materials
These data should be available in the country (countries) where the NES assessed is (to be) installed. The INPRO assessor should refer to publications of responsible national (or regional) organizations to get this input. Alternatively, the INPRO assessor can use some publications from international organizations such as the OECD/NEA–IAEA Red Book and the IAEA Integrated Nuclear Fuel Cycle Information System (INFCIS) that also list these resources based on a national estimation.
Long term perspective of national (regional) demand for resources of fissile and fertile materials
This input should be available to the INPRO assessor for the country (countries) where the NES is (to be) located. The NES demand for resources depends on the national (regional) scenario (e.g. rate of installation and types of nuclear facilities) of nuclear power introduction (or expansion), and, thus, the establishment of a national (regional) nuclear power scenario is a prerequisite to preparing this input (i.e. creation of such a national nuclear scenario is a prerequisite for an INPRO assessment).
To determine the demand for resources for the NES assessed, the INPRO assessor should receive information from (potential) technology suppliers (how many primary resources (e.g. tonnes of natural uranium) are needed for each nuclear facility), especially for nuclear reactor(s), e.g. tU per GW(e)·a.
If fissile/fertile materials are not recycled in the NES assessed (e.g. open or once through fuel cycle), estimation of the total (lifetime) uranium demand for the NES assessed is rather straightforward, namely, just the integration of demand of the primary resource per year over the projected lifetime of the system. Usually, this value should have been already determined in an energy system planning study that is, by definition, a prerequisite for an INPRO assessment (see overview of the INPRO methodology).
If resources are (to be) recycled within the NES assessed (e.g. an NES with a partly or completely closed fuel cycle), information is needed on how much fissile/fertile materials are recovered from spent fuel, which could be used as a secondary supply for the NES. Some of this information needed is design specific, e.g. the correlation between the nuclide composition of fresh fuel and spent fuel in a reactor, which depends on core design including the neutron spectrum, fuel arrangement (e.g. seed and blanket arrangements), burnup, etc. To determine the amount of recycled fissile/fertile materials, the results of more sophisticated tools for material flow analysis, such as the Nuclear Fuel Cycle Simulation System (NFCSS) or the Model for Energy Supply Strategy Alternatives and their General Environmental Impact (MESSAGE), are necessary; these are available on request from the IAEA.

Final assessment of CR1.1: Fissile/fertile material

Global demand and supply of fissile/fertile materials
A detailed study performed within the INPRO project — summarized in Appendix III — came to the conclusion that the currently identified global resources of natural uranium that have a high probability of being provided at reasonably low cost are sufficient to supply fuel to a global NES (consisting of thermal reactors) whose installed capacity could increase to 2500 GW(e) by the end of the century, which is approximately six times greater than the current installed capacity of less than 400 GW(e). The results presented in the Red Book 2011 — summarized in Appendix I — confirm this trend up to the year 2035, and predict that this trend will continue during this century. If the deployment of fast reactors (FRs) is realized in a sufficient amount, which appears likely at the moment in view of developments in a number of technology holder countries worldwide, the currently identified uranium resources (~18 × 10⁶ tU) would be capable of supporting the growth of a global NES with a capacity that is 12 times larger than that of today at the end of the century, i.e. with a capacity of 5000 GW(e). Thus, the balance of global demand and supply of natural uranium has been confirmed until the end of the century in this INPRO study.
INPRO assessors are asked to study the full reports summarized in Appendices I and III, familiarize themselves with the results, and document the main conclusions thereof in the final assessment report. It is also recommended that they contact the IAEA INPRO section, which has an ongoing project on global nuclear energy scenarios. If new studies on this issue become available, they should also be taken into account by the INPRO assessors.
National (regional) demand and supply of fissile/fertile materials
As the global resources of uranium have been found to be sufficient, it can also be concluded that each national NES will have access to sufficient uranium, as long as a global free market for natural uranium supply (and/or nuclear fuel) prevails. National or regional assessments could then be performed to understand how the country, in its national nuclear power programme, could benefit from its own domestic resources and how regional cooperation could potentially be fostered (see the discussion at the beginning of Section 3.2). For this purpose, it is recommended that the INPRO assessor determine the uranium resources necessary for the national (regional) NES assessed using one of the tools available from the IAEA (MESSAGE, NFCSS and Dynamic Energy System — Atomic Energy (DESAE)). To confirm the availability of the required resources, the assessor should take existing national (regional) resources into account.

Criterion CR1.2: Non-renewable materials

ᅠIndicator IN1.2: Quantity, Qi(t), of material type i available for use in the NES at time t.ᅠ

Acceptance limit AL1.2: Qj(t) > Dj(t), quantity available for NES, Qj(t), should be bigger than quantity needed, Dj(t), for any t < 100 years. In CR1.2, all non-renewable materials (other than fissile and fertile materials) are to be considered that must be continuously available to construct, operate and decommission an NES. As has already been mentioned at the beginning of Section 3.2, a global market exists for non-renewable materials other than fissile and fertile materials, and it is the assessment on a global scale that could prove ultimate compliance with the ALs for IN1.2. However, national and regional assessments also make sense and the more so because it may be much easier for a country to benefit from supplying its domestic non-renewable resources other than fissile and fertile materials for domestic construction of a foreign designed nuclear power plant. Countries may pursue this goal, even at the early stages of their nuclear energy programmes, and turnkey contracts for nuclear power plant construction may have up to 60–70% of the construction costs in domestic materials and labour. Any domestic materials should, of course, meet the reactor grade requirements of a nuclear power plant design. Assessment on the domestic and, potentially, regional scale may, therefore, help define potential benefits from indigenous resource use and foster mutually beneficial cooperation within a region; however, by itself, assessment on the domestic scale will not be sufficient to prove that the ALs for IN1.2 are met. The assessment of criterion CR1.2 should be performed by comparing the NES demand to global and national (regional) demand, and to available resources, also global and national (regional). Information on metal resources can be obtained from Ref.. Appendix II summarizes the results of a generic study that could be used for assessment of this criterion. This study, performed by the OECD/NEA and published in 2011, is based on life cycle data collected for the Swedish Ringhals plant that includes light water cooled reactors (three pressurized water reactors (PWRs) and one boiling water reactor (BWR)) commissioned between 1976 and 1983. In total, about 70 raw materials were evaluated that were needed for construction, used for operation and foreseen for decommissioning of this plant. The conclusion of the study was that even with a tenfold increase of global nuclear capacity by 2085 to 3720 GW(e), in such a global NES consisting exclusively of reactor types that are currently in operation with a once through fuel cycle, there is no shortage of any raw material to be expected until the end of the twenty-first century. The ongoing introduction of evolutionary reactors replacing currently operating reactors, and the foreseen inclusion of innovative reactors in the global NES, does not change this conclusion, although for the latter designs, limited information is currently available because of the early stage of development. It can also be anticipated that many innovative reactors will adopt non-water coolant technologies, resulting in an essentially different nomenclature of materials. Again, insufficient information is available, at the moment, to assess these differences. In addition to the materials covered in the OECD/NEA study, heavy water moderated reactors need several hundred tonnes of heavy water for startup, and could need several tonnes of it each year to replace losses. However, heavy water is abundant in normal water, albeit at a low concentration, and so there is no shortage of this raw material to be expected. Based on the OECD/NEA study, CR1.2 is met for all non-renewable materials (other than fissile and fertile materials) needed in a global NES and assuming a free market prevails also for a national NES. It is recommended that the INPRO assessor searches the public domain for newer studies on this issue.

Criterion CR1.3: Power supply to the nuclear energy system

ᅠIndicator IN1.3: P(t) = power available (from both internal and external sources) for use in the NES at time t.ᅠ

Acceptance limit AL1.3: P(t) ≥ PNES(t) for all t < 100 years, where PNES(t) is the power required by the NES at time t. An NES will, at any time, require power (electrical or other) for facility operations, facility construction, etc. The indicator P(t) is the power available at time t for use by the NES from all sources, both internal and external to the NES. At any time throughout the life cycle, this power should equal or exceed PNES(t), the power requirement of the NES at time t. At the beginning of the NES life cycle (i.e. during construction), all of the power would need to be available from external sources, while at later times, the source of much or all of the power for the operation of the NES and/or its growth may be internal to the NES. Thus, to assess CR1.3, the INPRO assessor should, in close cooperation with (potential) suppliers of the NES assessed: Determine the NES requirement of power (i.e. electricity) from outside during construction/operation/decommissioning, and when it would be required; Verify the availability of the required non-nuclear (e.g. fossil fuel, hydro) power from outside and corresponding resources during the lifetime of the NES. Regarding power supplied to NESs based on fossil fuel energy, several references exist on fossil fuel resources that can be used for the assessment, e.g. Refs. Scenarios for fossil fuel exploitation and use are described in these two references when discussing uranium scenarios.

Criterion CR1.4: End use of uranium

ᅠIndicator N1.4: Ueu = end use (net) energy (GW·h) delivered by the NES per tonne of uranium mined.ᅠ

Acceptance limit AL1.4: Ueu > U0; U0 = maximum end use achievable for an existing NES with a once through nuclear fuel cycle. CR1.4 should be addressed by integrating the sum of all energy uses throughout the lifetime of all components of the NES to determine the net (electric) energy generated by the NES assessed per tonne of natural uranium used, i.e. the value of Ueu. The calculated values for uranium use of the NES assessed per energy delivered should be compared with the uranium use efficiency of an existing NES with an open (once through) fuel cycle, i.e. the value of U0. There is a generic study available to the INPRO assessor defining U0, namely, the study documented in Ref.. This study determined, for current (around the year 2000) nuclear fuel cycles associated with light water reactors (LWRs) in western Europe, a net electricity delivery (to grid) per unit of uranium ore consumption in the range 42–50 GW·h/t natural uranium. An average value of 44 GW·h/t natural uranium can be assumed for electricity delivery of NESs in Europe. The range of end uses depends on the assumed burnup, the average enrichment of fresh fuel and the source of enrichment services (centrifuge enrichment uses about 60 times less energy than diffusion per separative work unit). Reference presents a simplified calculation of the end use of natural uranium in an NES with an open (once through) fuel cycle. It determined a value for U0 of 40.5 GW·h per tonne of natural uranium used. Thus, criterion CR1.4 is met, if the net energy delivered by the NES assessed per unit of uranium used is higher than the value of an existing NES consisting of an LWR with an open fuel cycle.

Criterion CR1.5: End use of thorium

ᅠIndicator IN1.5: Theu = end use (net) energy (GW·h) delivered by the NES per tonne of thorium mined.ᅠ

Acceptance limit AL1.5: Theu > Th0; Th0 = maximum end use achievable with a current operating thorium cycle. The calculated end use values for an NES designed to use a thorium (232Th/233U) fuel cycle should be compared with the thorium use efficiency of a current thorium cycle confirming the increased efficiency of the NES to be installed (developed). However, this criterion could not be assessed by a nuclear technology user at the time that this publication was written, because as of 2014, there was no NES operating on a thorium cycle. Therefore, this criterion is thought to be considered exclusively by nuclear technology developers.

Criterion CR1.6: End use of other non-renewable resources

ᅠIndicator IN1.6: Ci = end use (net) energy delivered by the NES per tonne of limited non-renewable resource consumed.ᅠ

Acceptance limit AL1.6: Ci > C0; C0 to be determined on a case specific basis. Cumulative consumption of non-renewable resources (other than fissile and fertile materials) per unit of net energy delivered (i.e. material use rate efficiency) should be compared with the results for an existing NES with an open fuel cycle. There is a generic study available for the INPRO assessor that defines C0 for some non-renewable materials, i.e. the study documented in Ref.. This study determined, for current (around year 2000) nuclear fuel cycles associated with LWRs in western Europe, the consumption of copper, iron and gravel (the latter as a measure of concrete use) as reported in Table 3 (more data on specific reactor type and country as well as on other resources are available in Ref.). The ranges of consumption depend upon the assumed key parameters for the different fuel cycles in the country and the type of LWR. Not surprisingly, the study shows that the highest material use throughout the life cycle is calculated for the construction phase of a nuclear power plant. To produce fuel assemblies for operating and evolutionary water cooled reactors, various zirconium alloys are currently used. One of the reasons for using zirconium alloys as fuel claddings is that zirconium has a low cross-section of neutron capture, which is necessary for efficient fuel utilization. However, zircon sand, which is the main source of zirconium, usually contains an admixture of hafnium in various quantities. Hafnium has an extremely high neutron capture cross-section, and needs to be separated from the zirconium used for nuclear fuel fabrication, which means that the cost of nuclear grade (refined) zirconium may depend on the amount of hafnium in the deposits. A study performed under the aegis of INPRO mentioned the zirconium availability issue in the framework of NES sustainability assessment. An operating reactor of 1 GW installed capacity annually consumes ~10 t of zirconium. Countries that plan on increasing their nuclear power capacity will substantially increase zirconium consumption, e.g. China expects the demand for zirconium by its nuclear power industry to exceed 8000 t/a during the next decade. An estimation of zirconium supply needed to utilize the total global amount of natural uranium resources of ~20 × 106 tU in PWR reactors can be performed as follows. The share of UO2 in a typical PWR fuel assembly amounts to approximately 0.7 of the total assembly weight. The rest of the assembly weight (0.3 of the total) comprises mainly fuel rod claddings, assembly nozzles and spacers. Conservatively assuming that 3 kg of zirconium is necessary to utilize 7 kg of UO2 and that uranium enrichment in the fuel is 4%, it can be approximately estimated that 1.2 × 106 t of zirconium would be necessary to use 20 × 106 tU. As the world resources of zircon exceeded 60 × 106 t, according to the US Geological Survey in 2013, it can be assumed that there will be no shortage of this material. However, as is summarized in the OECD/NEA study, zircon sand is produced as a by-product of titanium production, and zircon supply is heavily dependent on titanium demand. Supply is tight and oriented towards applications in the ceramics industry, because this sector covers over 50% of the total production. Annual global production of zirconium amounts to approximately 1.5 × 106 t (1.62 × 106 t in 2011 and 1.42 × 106 t in 2012). At the current consumption rate, world resources of zirconium will last less than 40 years. New explorations of zirconium deposits are expected to enlarge zirconium reserves. For other important non-renewable materials needed for NESs, a preliminary study published by the OECD/NEA can be used. Thus, the INPRO assessor should select the key materials determined during the assessment of criterion CR1.2, determine their accumulated consumption in the NES assessed and compare them to the consumption in an existing NES. Criterion CR1.5 is met if the consumption of non-renewable materials in the NES assessed per energy delivered is lower than the corresponding values for an existing NES. In the case when a given resource is not used in an existing NES, the assessor’s judgment should be based on the result of global production and consumption analysis.

Table 3. Examples of cumulative resource consumption (in year 2000) for european light water reactor energy chains

Material	Minimum (GW·h/t)	Maximum (GW·h/t)
Copper	1.68 × 102	2.07 × 102
Iron	2.93	3.66
Gravel	2.44 × 10-1	3.06 × 10-1

User requirement UR2: adequate net energy output

User requirement UR2: The energy output of the NES should exceed the energy required to implement, operate and decommission the NES within an acceptably short period.
The net energy output of an NES is the usable energy produced by the system over and above the energy required to install, operate and decommission the system, over its intended life cycle. The net energy balance (output minus input) should turn to a positive value in an acceptably short period after startup; obviously, the shorter the better.
The INPRO methodology has defined one criterion for UR2, as shown in Table 1.

Criterion CR2.1: Amortization time

ᅠIndicator IN2.1: TEQ = time required to match the total energy input into the NES with energy output (years).ᅠ

Acceptance limit AL2.1: TEQ << TL; TL = intended lifetime of NES. CR2.1 requires that the TEQ of an NES is adequately short, i.e. the time needed to generate the amount of power that is needed to install, operate and decommission the NES should be much shorter than the lifetime TL of the system. The value of TEQ depends on the purpose of the NES, e.g. whether the NES is to be used for power generation or if it is to be used as an MA burner for high level waste reduction. In the first case, the value of TEQ can be assumed to be lower or even much lower than for the second, because the second system should be designed to optimize MA burning, not for energy conversion. There is one generic study available to the INPRO assessor that defines the TEQ of a current NES, namely, the life cycle assessment study documented in Ref.. This study determined, for a current (year 2000) PWR operational in western Europe using uranium enriched by a centrifuge only and a partly closed fuel cycle (mono plutonium recycling by reprocessing of uranium spent fuel), an approximate TEQ of 5 months for a 40 year operational lifetime, with all energy requirements throughout the life cycle included. This value was not calculated by the software used in ecoinvent, but indirectly through the total (cumulative) waste energy divided by the direct electricity output from the power plant. A reference efficiency of 35% for the conversion of thermal energy to electricity was used to express the total energy requirements in electricity equivalent units. The average value of TEQ calculated for western European LWRs was ~17 months, owing to the relatively high share of enrichment by diffusion in 2000, which was assumed to be used for approximately 65% of the total supply of enriched uranium. Another generic study on NESs completed by the World Nuclear Association (WNA) in 2003 shows that the total amount of power used by a typical NES for construction, operation and decommissioning was far less than the power generated (by a factor of 20 or more). For an NES to be installed during the twenty-first century, it is expected that the ratio will be even higher because of more efficient fuel utilization, advanced designs and the use of improved materials and construction techniques. Thus, criterion CR2.1 is met for the NES assessed if its TEQ is adequately short, i.e. much shorter than the lifetime of the system and shorter than for an existing NES. For example, in the case of an NES (using a PWR with mono recycling of plutonium and centrifuges for enrichment) designed for power generation, TEQ should be less than 5 months. Instead of using the EPBT, the INPRO assessor could use the energy profit ratio (EPR) to evaluate this criterion. The EPR is the ratio of total energy output to input, whereas the EPBT is based on the difference of energy output and energy input.

Appendixes

• Appendix I
• Appendix II
• Appendix III
• Appendix IV

	[ + ] Assessment Methodology
Areas of INPRO Sustainability Assessment Overview • Economics • Safety (Nuclear Reactors) • Safety (NFCF) • Waste management • Environmental Impact on Stressors • Environmental Impact from Depletion of Resources • Infrastructure Requirements Basic Principle • User requirements • Criteria