On the choice of technology for a new uranium enrichment plant

On the choice of technology for a new uranium enrichment plant

Nuclear Engineering and Design 320 (2017) 9–16 Contents lists available at ScienceDirect Nuclear Engineering and Design journal homepage: www.elsevi...

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Nuclear Engineering and Design 320 (2017) 9–16

Contents lists available at ScienceDirect

Nuclear Engineering and Design journal homepage: www.elsevier.com/locate/nucengdes

On the choice of technology for a new uranium enrichment plant Alexander Pavlov National Research Nuclear University ‘‘MEPhI”, 31, Kashirskoe Shosse, Moscow 115409, Russia

h i g h l i g h t s  Countries developing nuclear power may desire to own the uranium enrichment plant.  In the world there is a choice of two potential suppliers of separation technology.  The method for initial evaluation of some costs for enrichment plant is suggested.  These costs depend mainly on the same individual characteristics of a centrifuge.  One of the two considered technologies is shown to have certain advantages.

a r t i c l e

i n f o

Article history: Received 16 March 2017 Received in revised form 12 May 2017 Accepted 15 May 2017

Keywords: Reactor fuel supply Enrichment plant Gas centrifuge Capital cost Operating cost

a b s t r a c t The question of the choice of technology for a new gas centrifuge uranium enrichment plant is considered and the major factors affecting the cost of construction and operation of such a venture are investigated. Using the method of ‘‘essential differences account” (EDA) these factors are compared for two hypothetical plants of equal capacity, using technology provided currently in the uranium enrichment market: the Russian and the West European. The analysis is performed of two parameters that affect the choice of separation technology: 1) the cost of the plant installed capacity, reflecting the capital cost of its construction, and 2) the financial loss due to failure probability of centrifuges in operation, affecting the plant operating costs. It is shown that the main differences in construction costs depend on the characteristics of the gas centrifuge (GC) used. It is also shown that the costs associated with the failed centrifuges replacement are mainly determined by the individual characteristics of centrifuges. The estimates made on the basis of available information show a clear advantage of one of the two considered technological platforms. Ó 2017 Elsevier B.V. All rights reserved.

1. Introduction The Chernobyl accident in 1986 seriously slowed the rapid development of nuclear energy that was taking place in the world in the second half of the 20th century. The negative impression left by the disaster in the minds of people, gradually receded into the past, and was replaced at the beginning of the new century by the revival of interest, especially in countries with rapidly growing economies, in the possible solution of their energy problems with the help of atomic power. This shift in global public opinion was reflected in the form of general expectations of the ‘‘nuclear renaissance”. Different countries have begun to implement projects related to the construction of nuclear power plants and to nuclear fuel necessary for them. The development of new generations of nuclear reactors advanced, construction of new uranium enrichment plants started, a new class of ‘‘juniors” in the uranium mining E-mail address: [email protected] http://dx.doi.org/10.1016/j.nucengdes.2017.05.014 0029-5493/Ó 2017 Elsevier B.V. All rights reserved.

industry had emerged. These positive processes and mood, which lasted about one and a half decades, quickly damped out as a result of the new strike produced by a combined effect of Fukushima disaster and the global economic crisis. Renaissance gave way to stagnation, and in some countries, such as Germany, to a complete pull back. Although these events have again strongly inhibited the global nuclear industry, but they have not led to a universal replacement of growth by reduction, which would mean the imminent disappearance of the nuclear power, the cherished hope of its long-standing opponents. We believe that this fact clearly indicates the objective demand of nuclear energy on the part of humanity. Today, as it follows from all historical processes logic, the global economic system is at the beginning of a new wave of its activity revival, energy needs growth and, as an inevitable consequence, a large-scale development of nuclear power. Also, based on the current level of nuclear industry technological safety, it can be considered a near-zero probability that the nuclear energy revival process, which already covered a considerable number of countries,

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could again be suddenly interrupted due to any incident or accident. As a result of this revival, or the beginning of a ‘‘new nuclear renaissance”, there will inevitably increase needs for nuclear fuel production, and, in particular, for the enrichment of natural uranium. Some countries, among the ‘‘newcomers” who are going to participate in the revival of nuclear energy activities can focus their efforts on the way to create their own elements of industrial nuclear fuel cycle. Those responsible for creating nuclear energy strategy in any country will be concerned about the future security of supply of their stations with all the components of the nuclear fuel cycle, from natural uranium to management of spent fuel. Some of those components obviously may not be achieved with the country’s available resources, for example, in the absence of native uranium deposits; but some may seem economically attractive as national enterprises. In particular, this may refer to the provision of uranium enrichment services. Of course, to develop own enrichment industry needs to take into account the limitations imposed by the international nonproliferation regime. At the same time, for the countries that demonstrate their commitment to the NPT1 and provide full transparency of their nuclear activities, there are no formal barriers to legitimate the creation of their own industry to enrich uranium – for the purposes of meeting the needs of their own nuclear power plants, and for the possible supply of enrichment services to the world market (Treaty on the Non-Proliferation of Nuclear Weapons, 1970). It seems very likely that in the coming years among the fastest growing countries of the ‘‘third” world will be such that, while remaining non-nuclear states2, would wish to have on their territory a uranium enrichment capacity enabling the achievement of these goals. The acquisition of such facilities for them will be most reasonably by way of purchase of the enterprise ‘‘turnkey” at the technology owner or participation with him in a joint project. A historical example of the first option was building by Rosatom a gas centrifuge plant (GCP) in China (Vsluh, 2008), the second scheme was initially followed by Urenco when it started to create the company Louisiana Energy Services (LES) in the United States. Self-development of enrichment technology is obviously not realistic: firstly, from an economic point of view, as a very complex and expensive technological problem, and secondly, due to the fact that despite the absence of formal prohibitions the attempt to start this activity would inevitably cause stiff opposition from the international community as being contrary to the objectives of nonproliferation of sensitive nuclear technologies. Notable examples are available in the modern history: the first consideration is illustrated by the failure of the multi-billion dollar project ‘‘American Centrifuge” in the United States (The United States stopped building its centrifugal enrichment plant, 2016), the second – by Iran’s nuclear activities, which led to long-term economic and political sanctions.

2. Statement of the problem The quite probable scenario is as follows. A certain country is planning the construction or already is building, most likely with external assistance, one or more nuclear power plants (NPPs) consisting of 6 to 12 nuclear units and is willing to optimize the management of nuclear fuel. Responsibility for fuel supply lies with the national organization responsible for operation of those nuclear 1 Non Proliferation Treaty (Treaty on the Non-Proliferation of Nuclear Weapons, 1970). 2 i.e. non-nuclear-weapon states. According to the NPT wording of the «nuclear state», it is the state, which has manufactured and exploded a nuclear explosive device prior to January 1, 1967. There are five countries: USA, USSR, UK, France and China.

power facilities. It does not matter if this organization is private or public, since due to the specifics of the subject all the issues of supply of nuclear materials will be under the control of the state anyway. Therefore, for the sake of brevity, bearing in mind the stakeholders in general, we shall speak simply of ‘‘customer” or ‘‘country.” Thus, this country wants for its nuclear power plants to have its own source of supply of enriched uranium, and more specifically, enrichment services. We are considering here this particular demand alone, suggesting that, in accordance with general practice, other components of the fuel cycle – natural uranium, conversion and fuel fabrication – could be purchased on the market. As for the amount needed for the purchase of enrichment services in the market this can vary from 1/3 to half the cost of the finished fuel. The output of a gas centrifuge separation plant is the service of natural uranium enrichment by fissile isotope U-235, as measured in separative work units – SWU3. SWU is a market commodity, the price of which is quoted in the uranium market and is published regularly by specialized companies, such as Trade Tech and Ux. Over the years, supply and demand for the SWU in this market are basically balanced, although in recent years the price of SWU tend to decrease. Based on the typical characteristics of modern nuclear reactors, one unit of 1000 MWt consumes, after initial core loading, in the average about 0.15 million SWU per year. At current market prices this is of the order of $12 million (World Nuclear Association, 2017). According to approximate economic evaluation to own enrichment plant compared to purchasing the separation work in the world market becomes profitable if the plant service is in demand by nuclear power plants with a total capacity of about 10–12 GW, that is by 10 to 12 typical nuclear power units. Then the annual production of the enrichment plant intended for local consumption must be 1.5–2 million SWU. This evaluation is qualitatively shown in the diagram taken from Grigorev (2014), see Fig. 1. There the costs of purchase of enrichment in the market (in blue color) grow in time with the NPP units commissioning. For comparison in red color is presented the curve of distribution in time of the expected costs associated with a centrifuge enrichment plant construction and its operations for SWU production at the rate of about 3 million SWU per year. It is shown that the cost of market SWU supply remains lower than GCP costs for cases with one (a) and six (b) nuclear reactors in operation, while for the number of units above ten (c) the supply by own plant becomes more economic. Choice of an appropriate moment for home GCP construction and commissioning would allow starting NPPs supply by domestic enrichment just when the generating capacity reaches the economic volume of 10GW. Although this illustration lacks rigor, since the correct analysis requires having a financial-economic model of the whole complex of NPP plus GCP (also see Section 4 below), it shows the basic rationale for having the enrichment capacity together with the nuclear generating capacity. If the country intends to expand its national atomic energy program, its generating capacity may reach 10 GW quickly enough. The enrichment plant economics will break even with guarantee if its capacity is no less than 3 million SWU per year. What will happen if the plant is built, but the pace of construction of nuclear power plants in the country slowed down? According to the World Nuclear Association today about 20 countries in the world have a solid nuclear energy development plans (World Nuclear Association, 2015). All forecasts of enrichment services in the world market say that the demand will not be reduced for at least 50 next years, even in the case if over some time a largescale implementation of a closed fuel cycle on the basis of fast

3 Because of SWU physical dimension the unit is sometimes denoted as kgSWU; also 1 ton SWU may be used instead of 1000 SWU.

A. Pavlov / Nuclear Engineering and Design 320 (2017) 9–16

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Fig. 1. Dependence of cost on time in two cases: plant construction and operation cost (1) or buying SWU on the market (2): a) for 1 nuclear reactor; b) for 6 reactors, and c) for 11 reactors (basing on the data from Grigorev (2014)).

reactors will start. Therefore, the owner of a new separation plant in the case of excess of SWU production capacity over domestic needs can count on the sale of separation work on the foreign market, which will hedge the profitability in this case. Thus, for the countries of mentioned category the strategy of acquisition of own separation capacities should look fairly rational. Considering the intertwining of government and private interests always present in nuclear industry and, therefore, ensured state support, business interest in such a project would certainly be high. So, we assume that the country has taken a decision on such a project, and there is no opposition on the side of international community since the said country acts as transparently as possible, it is a party to the NPT and to the Additional Protocol to it, agreeing to all mandatory inspection and verification according to the rules of the IAEA. Note that in the modern world a different behavior of the customer is practically impossible due to the available precedents in the past, which caused serious consequences (remember the already mentioned story of Iran, as well as events in Iraq and Libya). What will be then the practical steps by the customer – that is the relevant public authority of the country or its authorized organization? The project, as stated above, in the general view should consist in a commercial collaboration of alleged owner of the enterprise with the selected supplier of the technology and necessary equipment. Therefore, one of the first steps should be to select the object of interest, either the plant turnkey supplier or the partner to the joint venture – both from those available on the market. However the choice is small today: in the world there are only two potential suppliers of commercially efficient enrichment technology. Those are the State Atomic Energy Corporation, Rosatom (Russia) and Enrichment Technology Company, ETC, a joint venture of Urenco (UK, Germany, Holland) and Areva (France). Both of these companies have already carried out similar projects outside of their national borders: Rosatom in 1996–99 built a plant in China under the scheme «delivery turnkey», Urenco built in 2008 and operates now a plant in the United States. There is no reason to doubt that both suppliers may be interested today in implementing a similar project for another country. So, the task for the potential customer is to find who out of two suppliers offers the required product for the lowest price. In this paper, from the perspective of the hypothetical customer interests, some factors are analyzed that may influence his choice of the new enrichment plant supplier. Apart from purely qualitative considerations, two typical for the technology parameters will be discussed in more detail: 1) the cost of the plant installed capacity (denoted as C, in $/SWU per year), reflecting the capital cost of its construction, and 2) the losses associated with equipment failures during operation, affecting the cost of production (F, in $/SWU).

3. Main parameters of the considered separation technologies Differences in the technologies from which choice is made are considered below. Both are based on the method of centrifugal separation of isotopes, representing versions that differ in technical execution. The first applied at industrial scale was the Russian version which was developed in 1950–60 at the height of the Cold War; we denote it as a Russian Centrifuge technology, RCT. The second development completed in the 1970-ies was by a West European company Urenco, the equipment for which is currently produced by ETC. History of the gas centrifuge uranium enrichment technology is adequately presented in Sergeev (2002), Baranov (2005), Pavlov and Platov (2010). It is noteworthy that in the second half of the twentieth century almost all industrialized countries were engaged in development of various uranium enrichment technologies, often seeking to acquire atomic weapons capabilities and attributing to that enormous resources. Finally, the technical solution to the problem has been independently achieved, in addition to the five nuclear powers, only in South Africa, Brazil and Japan (and by not so independent way – in Pakistan and North Korea) (Pavlov and Platov, 2010; Lukash-Guli, 2010). However only two entities: the Russian Sredmash, Rosatom predecessor, and Urenco managed to establish an effective enrichment technology that proved to be commercially viable and competitive for exporting. No one else who tried, including the United States, succeeded in that. A key element of enriched uranium production process chain is the gas centrifuge (GC). In this piece of equipment the main developer know-how and core differences existing in separation technology are concentrated. GC features largely determine the economic parameters of the entire production. The most important of these are the output of a centrifuge, measured in SWU per year, and its power consumption being shown generally in kWh per 1 SWU. The fundamental importance have the price of the centrifuge that is included in the capital cost of the plant construction and the costs of maintenance, repair and replacement of faulty equipment during operation. These settings affect the cost of the separation work produced. SWU value also depends on several other parameters such as the cost of consumables, the cost of personnel, overhead costs, etc. While both technologies use the same separation principle, namely, the effect of radial separation of the mixture in a centrifugal force field with its multiple increase due to the excitation of the axial circulation flow, there are substantial differences between the GC (IA ‘‘Home News”, 2012). RCT and ETC centrifuges differ structurally in the following basic properties. GC ETC has a long (option TC-21 – up to 6 meters) carbon fiber rotor rotating with ‘‘supercritical” speed, that means exceeding the first resonance speed. Higher operating speed means better productivity of the machine, however to raise it above criticality poses much higher requirements to rotor materials. RCT centrifuges have a much shorter rotor

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(about 1 m), the rotation speed at older generation machines is subcritical, the GCs are combined in ‘‘aggregates” by 20 pieces which are mounted on racks up to 7 storeys high. The latest models of Russian centrifuges, the generations 9 and 9+, are using carbon fiber and have super critical rotor speed, but remain close in size to the previous generations of centrifuges, keeping aggregate and tiered mounting. External differences between the two types of centrifuges are seen on the photographs in Figs. 2 and 3. It should be emphasized that the producers do not disclose many of the parameters of their gas centrifuges. Technologies assessment presents certain difficulties due to the fact that manufacturers do not publish complete data on the economic characteristics of individual machines, as well as enterprises as a whole. However, in the open literature there are a number of studies (Verbin et al., 2001; Corporation for international business relations (IBR), 2005; Rothwell, 2009; Kemp, 2009; Urenco, 2017; Glaser, 2008; Borisevich, 2013; National Enrichment Facility Safety, 2017), allowing to figure out the required performance data with a reasonable degree of certainty. In particular, interesting data on the GC parameters are obtained in Rothwell (2009) by application of proposed in this work micro economic model to main enrichment facilities operating in the world. Also, a large amount of factual information is found in the report (National Enrichment Facility Safety, 2017) and the annual reports of the companies Urenco, LES and ETC (Urenco, 2017; LES, 2011). In the following discussion, specific figures are to be used only for general orientation on the order of values, based on available in the open literature information. Starting with the priority issues which we believe may be of interest to a potential buyer we will try to derive approaches to estimation of the two technologies, based on a comparison of a limited number of characteristics of the equipment and using available data on the ranges of basic values. Table 1 shows the typical ranges of values that distinguish the latest generation of centrifuges RCT and ETC. For GC parameter ranges estimation the sources (Verbin et al., 2001; Corporation for international business relations (IBR), 2005; LES, 2011) were used. 4. Comparative analysis methodology: EDA Today, virtually all SWUs for nuclear power plant needs in the world are produced using the gas centrifuge technology. The qual-

Fig. 3. Centrifuge TC-21 of ETC. Source: (La Radioactivite.com, 2009).

Table 1 Centrifuge parameter ranges for two technology versions. GC characteristics

ETC

RCT

Rotor length, m Output (p), SWU/year Centrifuge failure probability (k), 1/year Price of a single GC machine (c), $

5–6 40–100 103 10,000–15,000

1–1,5 6–10 <103 500–1000

ity of the enriched product is regulated in the contracts for the supply of enrichment services, as a rule, on the basis of the American Society for Testing and Materials (ASTM) standards. As noted above, a country wishing to acquire its own commercial business in the uranium enrichment market, should focus on the installed capacity of its enterprise at the level of 3 million SWU per year. To evaluate the cost-effectiveness of such a project its financial and economic model should be built that will allow, in accordance with conventional techniques, to determine its net present value (NPV), internal rate of return (IRR), discounted payback period (DPB) and other economic characteristics (Haritonov et al., 2012). The calculation of these values, as well as for any other investment project in the field of atomic energy, depends on many

Fig. 2. Russian centrifuges typical layout in the shop. Source: (Pavlov, 2008).

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factors, including such as the discount rate, plant operation term forecasts, exchange rates and market prices for the products, etc. (World Nuclear Association, 2017). The effectiveness of the project will also be determined by the cost of all that is needed to get it on foot, including its design, placement, licensing of local regulatory bodies for construction and operation, acquisition of basic and auxiliary equipment, site preparation, construction and commissioning. The full costs both capital and operational of the plant after its start determine production cost of the separation work unit, on which in the end will depend the success of this project. Obviously, the question that will interest investors and the owner of the future enterprise is the way its economic parameters may depend on the application of one or another version of the technology selected for the gas centrifuge plant. A detailed examination of the financial and economic model of the enterprise, of course, requires a certain knowledge of all the factors of costs and projected revenues above. By virtue of the above-mentioned closed-source information, an independent construction of such a model presents considerable difficulties and, strictly speaking, should be carried out jointly with the owner of the technology in the pre-proposal stage. At the same time, in the root it is a question of comparison of the two plants almost identical in everything except the main production equipment, the centrifuges. Therefore as a first approximation of such a comparison it seems correct enough to apply the method of Essential Differences Account (EDA) proposed by the author (the first versions used in Pavlov (2008, 2012)). The method consists in the allocation of the enterprise parameters that are known to be different for different versions of the technology used, in this case RCT and ETC, and considering their impact on the result while leaving out of account the options that will obviously be close at both plants. Essential differences in the GCs of RCT and ETC design are reflected primarily on the basic production shops of the enterprise where the separation equipment, the centrifuges and specific accessories (power supplies, control units, etc.) are located. The difference in the cost of the construction and equipping of such workshops will determine basically the difference in the total cost of the enterprise, using a particular technology. Differences that influence the cost of installed capacity (C in $ per SWU/year) will impact area of production facilities, as different centrifuges have different output per unit area of the shop. Both plants can occupy virtually identical total area of land (S) since the main production shops occupy, as a rule, a relatively small proportion of the total area – 15% to 20% of S. Therefore the effect of the difference in the total area of the two plants on the cost of installed capacity can be considered as not essential in the logic of EDA. Other components for both versions of the separation plant are very similar. Reception areas of incoming materials, condensationevaporation installations, cooling and heating units, filling the finished product in containers, tails management, energy supply and much more in the two plants using two comparable technologies, should not be fundamentally different, neither on the technological level, nor in cost. As stated above, we are going to analyze by the above method two characteristics:1) the cost of the installed capacity of the plant C, and 2) losses associated with failures of centrifuges in operation, denoted F (in $/SWU). We suggest that a comparison of these two cost categories can serve as a good criterion for the initial assessment of the economic advantages and disadvantages of the considered technologies. In further examination following the EDA method we shall identify the parameters that differ significantly in the two considered technologies and affect the differences in the expected costs mentioned above. To distinguish the parameters that do not differ

Table 2 List of centrifuge plant parameters. Parameter

Symbol

Units

Plant production capacity

~ M

Number of centrifuges at the plant Plant installed capacity cost

N C

One centrifuge cost (supplier price) Centrifuge output

c

SWU/ year pc $year/ SWU $/pc SWU/ yearpc

Ratio centrifuge price to its output Main production shops construction cost per unit of area Cost of accessory equipment per centrifuge Plant total area Main production shops area Output per area unit of main production shops Cost of work for replacing failed centrifuge Failure rate (probability of one centrifuge failure during one year) Time required to restore the temporarily retired capacity of one centrifuge Downtime loss coefficient (one day downtime cost) Full losses caused by a failure of one machine Number of failures in a year Total losses caused by failures in a year Operation costs component of full SWU cost Failure losses contribution to SWU cost SWU cost operational component without failure losses

~ p = M/ N D = c/p Ks Kc ~ S Sp

$year/ SWU $/m2 $/pc m2 m2 SWU/ yearm2

~ Qs = M/ Sp w k

$/pc 1/year

t

days/pc

~ E r n = kN R = rn Oc = G +F ~ F = R/M

$/days

G

$/pc pc/year $/year $/SWU $/SWU $/SWU

or have a negligible impact, the notations for those will be marked with . For example, in the essential parameters group there are obviously the output p and the price of one centrifuge c, and in the ‘‘not essential group”, there are the capacity of the enterprise ~ (for both plants the value is equal) and total area of the plant M ~ S (affects little, the explanation is given above). Settings for GCP and equipment necessary for further evaluation are listed in Table 2. 5. Essential components of the separation plant installed capacity cost ~ SWU/year, So we compare two plants of the same capacity M using the technologies: one RCT, and the other ETC. As a starting point we take the simple formula for the total discounted costs Z (Haritonov et al., 2012):

Z ¼ X þ Y  T; where X – overnight capital plant cost; Y – annual operating costs; T – the payback period of the enterprise. In the notation of Table 2:

~ X ¼ C  M;

~ Y ¼ Oc  M:

ð1Þ

In our problem, the capital cost per unit of installed capacity of ~ Generally it includes the the enterprise is considered: C ¼ X=M. costs associated with the construction of buildings Ccs and the cost of purchase of necessary equipment Ceq. Both of these values include components that depend on the type of technology used, and those that do not depend on it. In accordance with the EDA principle we allocate only the parts of those costs which are of interest to us, that is depending on the technology cost of construction and equipment, and write down the share of capital expenditure specific to the chosen technology:

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C ¼ C cs þ C eq :

Table 3 Values of significant plant parameters for two technology versions.

Specific for the selected technology share of construction costs per unit of output 1 SWU/year is expressed as:

~ C cs ¼ K s  Sp =M; where Ks is the cost of construction of the main production shops ~ the plant output. Using the outper unit of area, Sp is their area, Mis ~ p, we get for the specific put per unit area of the main shops Qs = M/S construction costs:

C cs ¼ K s =Q s : Specific, i.e. depending on the technology, equipment costs consist of the acquisition of basic equipment – centrifuges at a price of c and the auxiliary equipment, the specificity of which is determined by the application required by the technology, either RCT or ETC. The cost of such accessories falling to one centrifuge is denoted by Kc. Then, for the enterprise numbering N centrifuges the costs for specific equipment upon unit of installed capacity will be:

~ C eq ¼ ðc  N þ Kc  NÞ=M: Thus, dependent on the type of technology capital costs are:

~ C ¼ C cs þ C eq ¼ K s =Q s þ ðc þ K c ÞN=M: ~ Or, using N ¼ M=p, obtain a formula including only the values depending on the specific technology:

C ¼ K s =Q s þ ðc þ K c Þ=p:

ð2Þ

As a result, specific to the technology capital cost per unit of installed capacity will arise from the construction cost per square meter of the main shops, divided by the output per unit area of the major shops, and the amount of a centrifuge price c plus the cost of accessories per centrifuge the Kc, divided by the capacity of a centrifuge. It follows that the most preferred is the technology that provides the minimum characteristics c, Kc, Ks, and maximum characteristics included in the denominator, the Qs and p, since it provides the minimum cost of the installed capacity of the plant. This seemingly trivial conclusion, nevertheless emphasizes some features of the two compared technologies, if the characteristic value ranges are considered.

Charachteristic

ETC

RCT

Number of centrifuges N, pc Centrifuge output p, SWU/yearpc Centrifuge price c, $/pc Ratio centrifuge price to output D = c/p, $year/SWU Cost of accessory equipment per centrifuge Kc, $/pc Main production shops construction cost per unit of area Ks, $/m2 Output per area unit of main production shops Qs, SWU/ yearm2 Installed capacity cost C, $year/SWU

30,000 100 15,000 150 5000 500

300,000 10 1000 100 200 500

400

400

200

120

Firstly, the parameters Ks and Qs are practically equal for both technological platforms. This is not surprising when we remember that the Russian technology uses a multi-tiered arrangement of centrifuges that makes those parameters similar at ETC and RCT. Besides, their quotient is very small compared to the other terms in (2). Furthermore, the cost of specific auxiliary equipment Kc in both technologies is much lower than c. In the end, the deciding role among the components of the formula (2) is played by individual characteristic of a centrifuge – the ratio of its purchase price for its performance D = c/p. This particular value specific for each technology makes the main contribution to the installed capacity cost of the separation plant. Therefore very roughly this cost can be estimated as:

C ffi D ¼ c=p:

ð3Þ

Other cost factors, such as design, construction, general purpose auxiliary equipment, production facilities, etc. are far less important in assessing the benefits of the centrifuge versions, and can be neglected in the first comparison. The lower the parameter D, the lower the SWU capital cost component. Given that the characteristic values of the total cost of the installed capacity for centrifuges produced in Russia, and for centrifuges ETC are in the range of 400–800 dollars per SWU per year (Rothwell, 2009), the difference in the specific component of the cost of $ 80 per SWU/ year (Table 3) provides significant value. For the current plant capacity of 3 million SWU/year, this difference means potential savings of $ 240 million in capital expenses.

6. Installed capacity costs comparison for two technologies Eq. (2) allows for an initial assessment of the two technologies under consideration, if we know the components included in it. We shall apply this approach to a hypothetical separation plant with a capacity of 3 million SWU per year using data shown in Tables 1 and 3. The assumption is that the client seeking to acquire the best-performing technology will choose maximum performance and accordingly centrifuges price ranges from the values given in the Table 1. The rest of the required parameters Kc, Ks and Qs are derived on the basis of data from the sources mentioned in Section 3. The centrifuge models with the parameters referred to here (TS-21 from ETC and PGC-8 from RCT) have been developed by both manufacturers about 10 years ago and are currently most widely supplied to separation plants. Also it should be noted that different or changing macroeconomic parameters in the country where the plant is built could affect the relative price performance of the equipment and construction works. Therefore, the examples given here are only illustrative of the method proposed to the potential customer as a tool for an initial assessment of its object of interest. Input data and the calculated cost of installed SWU for the two technologies are summarized in Table 3. Some comments can be given in addition to the figures in this Table.

7. Contribution of centrifuge failure losses to the plant operating costs Let us now consider the second part of the problem formulated in Section 2. For potential owner of the separation plant its operational efficiency is of no less interest than its capital cost. That, in turn, is determined by many components that depend both on the particular centrifuge technology, and on the factors of production in the country placing the plant. The latter include the costs of electricity, water supply, manpower, consumables, in other words all the costs arising from the operation. As noted with respect to capital expenditures, the comparative analysis of the operational component of the cost of SWU production for different centrifuge versions is also very difficult due to the fact that almost all the information about the performance characteristics of the technology manufacturers is confidential. Nevertheless, the approximate evaluation of the data available in Sergeev (2002), Corporation for international business relations (IBR) (2005), LES (2011) and Pavlov (2012), should be sufficient for purposes of the present work. Values used herein are also listed in Table 2. In accordance with the applicable approach, the EDA method of ‘‘essential differences account” we consider the technology

A. Pavlov / Nuclear Engineering and Design 320 (2017) 9–16

dependent share of operational component Oc (in $/SWU) of the total cost of production Y, averaged over the year, in accordance with (1): ~ Oc ¼ Y=M: It can be represented as follows:

Oc ¼ G þ F;

ð4Þ

where G is the sum of all production factors affecting the operational component, and the second term

~ F ¼ R=M

ð5Þ

describes the addition to the SWU cost due to failures of the centrifuge equipment only. The value of R is the total financial loss of the enterprise from the centrifuge failures that occurred during the year. It should be emphasized that the evaluation of the benefits of a technology version in terms of operational cost component generally demands to know the contribution of two terms in equation (4). It is obvious that both these terms essentially depend on the characteristics of centrifuges, but in accordance with the objectives set forth in Section 2 factor G will remain outside the scope of this study, i.e. in this case the problem will be considered only partially. However, to get an idea of the magnitude of the F factor, we can compare it to the cost impact for different versions of centrifuge technology. The role of this factor in operating costs can be significant, if it is not negligible compared with the value of G. Let us estimate the impact of failure events in the operating costs and the produced SWU cost first theoretically and then try to apply this estimate to the said varieties of technologies, using information known from public publications. The total separation plant annual losses from the failures are:

R ¼ rkN; where the coefficient k is a probability of failure of a centrifuge for the year, and r is the financial losses caused by a failure of the machine, including the cost of replacing c + w and losses from downtime caused by the event for the time required for replacement:

~ r ¼ c þ w þ Et:

ð6Þ

The value of the loss component in the cost of failure (5) is represented as:

~ ¼ rkN=E ~ F ¼ R=E or:

F ¼ rk=p

ð7Þ

Formula (7) leads to the conclusion that the increase in the cost of SWU due to any losses in the year related to the centrifuge failure, depends only on the individual centrifuge characteristics: its reliability k, its performance p and characteristic costs r associated with failure repair. Before proceeding to the assessment of the practical value of the factor F for known RCT and ETC technologies, it is useful to make a few comments. Differences in size and machine performance lead to significant differences in the characteristics of their operation, the cost of electricity and other resources. In relation to the issue we are interested here, that is to treatment of centrifuges in case of their failure, the plant operators have to adhere to different tactics. At Urenco plants operating ETC centrifuges the backup machines are previewed, which are operatively connected to a cascade, where there was a failure of the machine, saving downtime and preventing a decrease in its performance at the time of replacement or repair. It certainly leads to additional costs for the plant to buy

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and maintain the reserve fleet (estimated at up to 10% of the power plant (LES, 2011). In the case of RCT technology, due to the relatively low productivity of the machine and aggregate arrangement by 20 pieces, the failure of a single centrifuge does not require any serious action to replace or repair and, therefore, practically does not entail costs. The failure of the RCT centrifuge leads to its automatic shutdown from the stage, with almost no effect on its performance. The failure of a single gas centrifuge machine does not cause any switching off neither of the whole aggregate nor any other element of the separation cascade. Even in the event of need to replace the centrifuges, that operation at Russian plants is very inexpensive. Thus, even a qualitative examination of the problem suggests that the costs caused by the emergency centrifuge stop, in two versions of the technology must be very different. If we consider in addition the differences in the behavior of centrifuges due to serious accidents, such as mechanical destruction of the machine body, situations caused by the earthquake or the like, the advantage of small size and capacity, and, accordingly, a smaller scale of the consequences of accidents will be even more essential. Taking into account the assessments made above, we may consider for both producers the cost of work on the centrifuge replace~ in the formula (6) a small quantity ment and related losses, w + Et in comparison with the centrifuge cost c (in the case of RCT, this amount is close to zero). Then the formula (7) becomes:

F ffi ck=p ¼ kD

ð8Þ

Thus, the values determining costs related to failures are the machine reliability coefficient k and the already familiar parameter D = c/p. The coefficient k in Russian centrifuges is typically less than a tenth of a percent per year (IA ‘‘Home News‘‘, 2012; Pavlov, 2012). It is evident that this assessment leads to the conclusion, which is close to that obtained when considering the technology specific capital expenditures C (see (3)), with the only difference that in the impact on the cost of operating losses caused by failures of centrifuges, equally important are the factor D = c/p and the factor k of the machine actual reliability. And because the required correction to the cost of production is equal to the product of these two factors in the case of equality of centrifuges failure rate a decisive influence on the cost once again will have the value of D, i.e. a machine price related to the machine performance. For a specific example, we use the data from Tables 1 and 3, making a reservation again that the calculations here are very approximate and serve to illustrate the proposed EDA method for the purposes of primary comparative evaluation only. The failure probability factor k for comparable technologies is of the order of 103 and the D values are:

DETC  150 DRCT  100: In absolute figures, this means an increase in cost in the amount F for centrifuge ETC ffi 0:15 dollars per SWU and for Russian technology < 0.1 dollars per SWU in relation to the cost which would be at the absolute reliability of the machines k = 0. For 3 million SWU plant capacity it gives total operational annual losses due to machine failures R equal to $450,000/year for ETC and less than $300,000/year for RCT. However in case of ETC, as noted above, the value is attained while increasing capital cost for keeping in reserve certain number of redundant centrifuges.

8. Conclusions 1. A method is suggested for comparing two uranium enrichment technologies presented on the world market, which allows to

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2.

3.

4.

5.

A. Pavlov / Nuclear Engineering and Design 320 (2017) 9–16

make an initial assessment of the two major categories of costs for newly built separation plant: 1) the cost of the installed capacity of the plant, reflecting the capital cost of its construction, and 2) financial losses due to possible centrifuge failures in the operation of the plant. Evaluation of capital cost per unit of installed capacity is the decisive factor in the selection of the separation technology. It is shown that this value is directly related to individual characteristics of a single centrifuge, expressed as the ratio of its purchase price to its output, which defines the main contribution of specifics of technology to the cost of installed capacity of the separation plant. Calculation shows that the cost of the installed capacity for separation plants of 3 million SWU per year, using RCT technology and ETC technology, may differ in favor of the first to the amount of several hundred million dollars. The component of the SWU cost associated with failures also depends on the individual characteristics of the centrifuge and is equal to the product of the failure rate on the ratio of centrifuge purchase price to its output. In case of equal failure rates of different types of centrifuges, the preferred version is the technology with a minimum value of the ratio of the purchase price to output of a single GC. Analysis of the available data on the parameters of the compared technologies leads to the conclusion that the absolute value of the addition to the operational component of the cost of production due to centrifuge failure losses is relatively small and is less than 0.2 dollars per SWU. However, this value is also better in RCT technology.

Funding This research was partially funded by the National Research Nuclear University MEPhI Academic Excellence Project (contracts No. 02.a03.21.0005, 27.08.2013). Acknowledgment The author is grateful to Professor V.D. Borisevich for valuable discussions during the work on this paper. References Baranov, V.Yu. (Ed.), 2005. Isotopes: properties, production, applications. In 2 volumes, Moscow, PhysMathLit, ISBN-5-9221-0522-1 (in Russian). Borisevich, V. et al., 2013. Assessment of parameters of gas centrifuge and separation cascade basing on integral characteristics of separation plant. Nucl. Eng. Des. 265, 1066–1070. http://dx.doi.org/10.1016/j.nucengdes.2013.10.006. Corporation for international business relations (IBR), 2005. Russian uranium enrichment industry. State and prospects. Report for 2004, Moscow.

Glaser, A., 2008. Characteristics of the gas centrifuge for uranium enrichment and their relevance for nuclear weapon proliferation. Sci. Global Security 16, 1–25. http://dx.doi.org/10.1080/08929880802335998. Grigorev, G.Yu., 2014. Development of nuclear energy after Fukushima and evaluation of global needs of separation work (On the materials published in the Russian and foreign press), NRC ‘‘Kurchatov Institute”, Moscow, 18/04/2014. (public lecture, in Russian). Haritonov, V.V., et al., 2012. Economic and analytical models of nuclear power development dynamics. Monograph, Moscow, MEPhI, 76 p. ISBN 978-5-72621685-0 (in Russian). IA ‘‘Home News” (Sverdlovsk region), 25.10.2012, Gennady Solovyov: Our centrifuge is necessary for Americans. http://tvel.ru/wps/wcm/connect/tvel/ tvelsite/presscentre/smi/70490a004d388459a621f67b301cae75 (accessed 10.03.2017). Kemp, R.Scott, 2009. Gas centrifuge theory and development: a review of U.S. programs. Sci. Global Security 17 (1), 1–19. http://dx.doi.org/10.1080/ 08929880802335816. La Radioactivite.com, 2009. Avancées techiques et risques de proliferation, http:// www.laradioactivite.com/fr/site/pages/EnrichissementPerspectives.htm (accessed 10.03.2017). LES, ETS, Annual reports, 2007-2011. https://www.enritec.com/; www.urenco.com About Us Company Structure. Lukash-Guli, S., 2010. The spread of centrifuge technology from Pakistan: an underground network of Abdul Qadeer Khan. Nuclear Club 2, 24–27 (in Russian). National Enrichment Facility Safety Report, 2004–2005, http//pbadupws.nrc.gov/ ML0606/ML060680655.pdf. (accessed 10.03.2017). Pavlov, A.V., 2008. Comparative analysis of the construction cost for a new uranium enrichment plant with various types of gas centrifuges. Proceedings of the 10-th International Workshop on Separation Phenomena in Liquids and Gases, August 11–14, 2008, Angra dos Reis, Brazil. Pavlov, A.V., 2012. Centrifuge reliability as a factor of competitiveness of different gas centrifuge technologies. Proceedings of the 12-th International Workshop on Separation Phenomena in Liquids and Gases, June 4–8, 2012, Paris, France. Pavlov, A., Platov, M., 2010. Uranium enrichment: proliferation of gas centrifuge technology in the world. Nuclear Club, №2, 8-14 .; Pavlov, A., Platov, M., 2010b. Proliferation of uranium enrichment technology: the risks and threats. Nuclear Club, №4, 32-36 (in Russian). http://ceness-russia.org/rus/NuclearClubjournal/. Rothwell, G., 2009. Market power in uranium enrichment. Sci. Global Security 17, 132–154. http://dx.doi.org/10.1080/08929880903423586. Sergeev, V.I. (Ed.), 2002. The design and creation of a gas centrifuge isotope separation method in the USSR (Russia), St. Petersburg, Oblik, 496 p. ISBN-585976-228-3 (in Russian). The United States stopped building its centrifugal enrichment plant, 2016. https:// ria.ru/atomtec/20160224/1379644137.html; http://www.world-nuclear-news. org/C-American-Centrifuge-demonstration-plant-completes-operations2202167.html (accessed 10.03.2017). Treaty on the Non-Proliferation of Nuclear Weapons, 1970. https://www.un.org/ disarmament/wmd/nuclear/npt/ (accessed 10.03.2017). Urenco, Annual reports, http://www.urenco.com/investors/group-reports (accessed 10.03.2017). Verbin, Y.V., Zavadskyi, M.I., et al., 2001, Economic systems of separation plants modernization program for the period up to 2015. In: Atomic Industry Economics. Proceedings of the Section ‘‘Economics and Prognoses in Nuclear Power”, Moscow, CNIIAI, pp 81–86. ISBN 5-87911-070-2 (in Russian). Vsluh R.U., 2008. Russia will build a uranium enrichment plant in China. http:// www.vsluh.ru/news/oilgas/142566/ (in Russian), (accessed 10.03.2017). World Nuclear Association, 2015. The Nuclear Fuel Report: Global Scenarios for Demand and Supply Availability 2015–2035. September 2015 Report No. 2015/ 007 ISBN: 978-0-9931019-0-8. World Nuclear Association, 2017. The Economics of Nuclear Power (Updated January 2017). http://www.world-nuclear.org/information-library/economicaspects/economics-of-nuclear-power.aspx (accessed 10.03.2017)