National Nuclear Power Research Articles

Challenges and Progress in Spent Ion-Exchange Resin Management at NPPs

The management of radioactive spent ion-exchange resins poses significant challenges for NPPs, due to the lack of economically viable and efficient processing technologies. Such a situation necessitates urgent technological solutions. Historically, conventional methods of radioactive waste treatment have struggled to address the unique properties of spent ion-exchange resins, resulting in their gradual accumulation at industrial sites. At present, the accumulation of spent ion-exchange resins at Ukrainian NPPs has reached critical level, so that addressing radioactive waste management within the national nuclear power industry necessitates two distinct strategies: an immediate technological solution to condition and dispose of the accumulated spent ion-exchange resins, and a sophisticated method aimed at eliminating critical accumulation of spent ion-exchange resins in the future. This publication explores the context and the current status of spent ion-exchange resins management at Ukrainian NPPs, highlighting the efforts to develop and implement treatment technologies, both well-known and innovative. Various methods, including geopolymerization, UHF-vitrification, cementation, and decontamination, are assessed and compared for their feasibility and effectiveness. The study emphasizes the need for innovative approaches to yield safer, more stable, and volume-reduced end-products compared to conventional methods. Additionally, the paper discusses ongoing research endeavors and the importance of knowledge dissemination within the scientific community. Despite challenges, there is growing momentum towards finding practical solutions for spent ion-exchange resins treatment, emphasizing the need for continued research and innovation in this critical area of radioactive waste management. By addressing these challenges and advancing technological solutions, Ukraine can mitigate the accumulation of spent ion-exchange resins and enhance radioactive waste management practices in the national nuclear power industry.

Breaking the iron triangle around nuclear safety regulation: The cases of France, Japan, and India

AbstractThe International Atomic Energy Agency asserts that the regulation of the safety of civil nuclear power requires national regulatory agencies to be effectively independent. However, in the early years of national civil nuclear power programs national nuclear industries were dominated by iron triangles or subgovernments of powerful actors with an interest in promoting the industry. The creation of an independent safety regulator requires a radical restructuring of the national governance framework. Windows of opportunity or critical junctures for such reform occur only occasionally. This paper examines the cases of France, Japan, and India to identify the factors that determine the degree of success in attempts to break the power of nuclear iron triangles or subgovernments and create an effectively independent regulator. This analysis shows a serious nuclear accident can create the opportunity to dismantle an iron triangle. The extent and speed with which reforms can be implemented depend greatly on pre‐existing and prevailing conditions. Key determinants include the power structures and attitudes toward nuclear power in elite politics, the degree of engagement of civil society, and pressures from international organizations. Of these, the first, elite politics, appears to be the most important in these three cases.

Challenges in nuclear energy adoption: Why nuclear energy newcomer countries put nuclear power programs on hold?

The pressing need to mitigate greenhouse gas emissions has stimulated a renewed interest in nuclear energy worldwide. However, while numerous countries have shown interest in nuclear power over the course of history, many of them have not continued their pursuit and chosen to defer or abandon their peaceful nuclear power projects. Scrapping a national nuclear power program after making initial efforts implies significant challenges in such a course or a waste of national resources. Therefore, this study aims to identify the crucial factors that influence a country's decision to terminate or hold off its peaceful nuclear power programs. Our empirical analyses demonstrate that major nuclear accidents and leadership changes are significant factors that lead countries to terminate or defer their nuclear power programs. Additionally, we highlight that domestic politics (democracy), lack of military alliance with major nuclear suppliers, low electricity demand, and national energy security environments (energy import, crude oil price) can hamper a country's possibility of regaining interest in a nuclear power program after it has been scrapped, suspended, or deferred. The findings of this study have significant implications for policymakers and stakeholders in the energy sector as they strive to balance the competing demands of energy security, and environmental sustainability.

Decision­making support system regarding optimal ventilation control of NBK CHANPP

The purpose of the New Safe Confinement (NSC) is to protect the environment during the removal of radioactive materials from the destroyed block #4 and the dismantling of unstable structures of the destroyed "Shelter" facility. Since the planned work at the Chernobyl NPP is accompanied by large emissions of radioactive aerosols (RA), which pose a significant risk to the surrounding environment and personnel — their assessment, forecasting, as well as optimal management of ventilation units (VU) in order to minimize these emissions to an important extent determines success and safety carrying out such works. This paper presents the architecture and an example of the practical implementation of the decision support system (DSPR) for the management of ventilation units of the National Nuclear Power Plant of the Chernobyl Nuclear Power Plant, which allows finding the optimal operating parameters of the nuclear power plant, while minimizing the consumption of electricity and reducing the negative impact of radioactive aerosols, provides a convenient user interface for modeling and visualization works of the NBK University. An approach to development is described, which provides isolation of modules, ease of testing and transfer of the developed software between environments, and the possibility of further expansion of the system's functionality.

Assessment of public knowledge, perception, and acceptance of nuclear power in Bangladesh

Public perception plays a crucial role in the successful completion of a nuclear power project. As a newcomer country to nuclear power, there are lots of misconceptions among the Bangladeshi people about nuclear energy. Consequently, it is crucial to minimize all the doubts among mass people and build up their positive outlook toward nuclear power. This demands a comprehensive survey to figure out the public opinion, concerns, false impressions, and knowledge gap regarding nuclear power. In the present study, these issues were addressed by a survey that was responded to by 661 persons for the 24 survey questions. The questions were categorized based on information, knowledge, faith, benefit, awareness, and technology. Feedback and responders' basic demographic and socioeconomic information were collected from various locations in Bangladesh through online and in-person surveys. The responses were analyzed in both statistical and descriptive ways. Some of the feedback was found to vary with age, sex, and education level while others were quite independent of these parameters. It is found that socio-economic development and energy security can be achieved by the inclusion of nuclear energy in the power system master plan of the country. However, huge knowledge gaps and misconceptions were found among the public regarding nuclear energy. As per feedback, political instability and corruption may affect the national nuclear power project in Bangladesh. Low faith in the existing rules & regulations for nuclear power programs was also observed. The result of this study will be handy to develop the communication and public awareness strategy for a successful nuclear power project in Bangladesh.

3D Cloud Rendering Visualization based on Nuclear Power Industrial Internet

Industrial Internet is a new generation of information and communication technology, which is a deep integration of industrial economy with new infrastructure, application mode and industrial ecology. As the development of nuclear power industry, it raises many demands on the use of industrial internet. China National Nuclear Power has been devoted to constructing the Nuclear Power Industrial Internet since 2018. Many of its business and process needs 3D visualizationto demonstrate the real-time operating data. Therefore, a cloud rendering technical proposal is designed to realize this purpose. The configuration and working flow of the cloud rendering are described in detail. Finally, a use-case is applied to verify the technical proposal. Some future work for improvement is given.

The Role of Strategic Diplomacy in the National Nuclear Power Plant Development Plan in Indonesia in Supporting Energy and National Defense

Energy diplomacy as a country's foreign policy agenda in securing access to international energy sources. The significance of energy for a country can always be a cause or proxy for its foreign policy or even its military actions. The plan for the development of nuclear power plants in Indonesia in support of the climate change program is based on global agreements and is able to provide a deterrent effect on national defense. However, until now the role of defense diplomacy in achieving national interests has not been optimal and its achievements are still limited to defense issues only (Sudarsono et al., 2018). This study aims to analyze the role of diplomacy on energy and defense, where diplomacy provides a first treat on energy, thereby realizing national energy security supported by defense diplomacy. This study uses a literature study to collect relevant data related to energy diplomacy, nuclear power plant development plans to support the NDC program, and defense diplomacy. The results of the study indicate that a diplomacy synergy is needed in achieving the national interest. Defense diplomacy can be synergized with energy diplomacy, which in this case is able to accelerate the development of nuclear power plants in Indonesia which provides a multiplier effect both in terms of energy security in the issue of climate change, even to the deterrent effect of Indonesian defense. The effect of diplomacy on energy indicates that diplomacy has a significant role in politics and the economy that a country's energy can create.

The Role of Strategic Diplomacy in the National Nuclear Power Plant Development Plan in Indonesia in Supporting Energy and National Defense

The Role of Strategic Diplomacy in the National Nuclear Power Plant Development Plan in Indonesia in Supporting Energy and National Defense

Applicability Analysis of Pre-cracked Material for SHPB during the High-level Radioactive Waste Geo-disposal

According to the national nuclear power plan, the high-level radioactive waste should be disposed safety and effectively. And the deep geological disposal is the main way, which is influenced by the surrounding rock and soil, especially the physical and mechanical properties. Currently, the SHPB is mature equipment for the material’s dynamic testing. It is mainly used to load the entire specimen, however, the specimen with the pre-crack is less used. Firstly, it should satisfy two hypotheses, i.e. the one dimension stress wave and the stress equalization when using the SHPB to measure the mechanics characteristics of the material, especially for the pre-cracked specimen. Then, from the point of stress equalization along the specimen, emphasize the importance of the dynamic force equilibrium during the testing data processing. Finally, the SHPB testing system could also be applied to the pre-cracked specimen has been proposed.

From Insight to Innovation: Engineering Ideas That Transformed America in the Twentieth Century by David P. Billington Jr. (review).

Reviewed by: From Insight to Innovation: Engineering Ideas That Transformed America in the Twentieth Century by David P. Billington Jr. Arthur Daemmrich (bio) From Insight to Innovation: Engineering Ideas That Transformed America in the Twentieth Century By David P. Billington Jr. Cambridge, MA: MIT Press, 2020. Pp. 336. In this well-crafted history of major twentieth-century engineering-based technologies, David Billington Jr., covers dams, the national highway system, skyscrapers, nuclear power, and jet engines before shifting to development of transistors, microchips, personal computers, and the internet. Written with a generally educated reader in mind, Billington's text includes nicely rendered line drawings and illustrations. Unusually for a historical text, the author includes boxes in each chapter with technical descriptions and some mathematical and chemical formulas, presented in clear and understandable prose. Billington does not present technology as proceeding under its own inexorable logic, instead giving primacy to the engineers who developed and deployed key insights. He introduces these engineers—including a few women, like Marilyn Jorgenson Reece, who is covered in a chapter on "Highways and Skyscrapers"—with some brief context on their backgrounds. While the book does not go into any great biographical depth, Billington does not shy away from honest assessments, like that of William Shockley's racist views of intelligence. However, the focus throughout is on the advances in technology and engineering, not the engineers, changes to engineering education over time, or who becomes an engineer in America. The book concludes with several broad insights. First, historical engineering projects left physical legacies and created path-dependency that is often overlooked. Second, the government has a large and ongoing role in the development of major technology systems, both as a direct sponsor of large projects and as a purchaser, primarily through the military for the examples of transistors and microchips. Third, largescale engineering should be more attentive to the environment in the future. None of these will surprise readers of Technology and Culture. The audience for this book is not entirely clear, in part because its approach [End Page 1262] to the history of technology is rather retrograde. The book's chapters each stand more or less on their own, and there is little overall narrative or analysis across the technologies and systems described. There are hints at political choices for each area, but these are quickly set aside and presented without historical depth. The reader gets a sense that political and policy tradeoffs are important—for example between the environment and employment as exemplified by dams, or between energy generation and human health risks as exemplified by nuclear power—but does not learn that design and engineering decisions were shaped deeply by those debates. The book would be stronger if it had also explored changes over time to the ways in which public concerns with technological systems have been raised and resolved. Likewise, major topics in recent scholarship in the history of technology are largely absent. Little attention and no voice is given to people and communities displaced by the large technological systems described. Nor does the book give attention to inclusion and involvement (or lack thereof) of women and People of Color in engineering. Readers are not given a discussion of racist decisions, such as the location of highways that dispossessed Black Americans and broke up previously stable communities. Similarly, despite ostensibly being a book about innovation, the book does not explicitly analyze or offer insights on how to think about innovation. Consumers make no appearance in the book, even when discussing the personal computer and the internet. Billington sidesteps the maintenance and unintended economic consequences of the dams, roads, and power systems he describes. Instead, the book explains how dams, roads, nuclear power, jet engines, transistors, microchips, and the internet work and gives quick introductions to the lead engineers for key technology milestones of the twentieth century. It succeeds admirably in this. But who is seeking that set of historical insights separated from the political, policy, consumer market, and other factors that have drawn the attention of historians and sociologists for the past fifty years? Ironically, even while opening one set of black boxes and describing in lucid and approachable language how various technologies...

Influence of steam heat transfer tube damage characteristics on burst pressure

The corrosion damage and leakage of heat transfer tube of steam generator were important factors of nuclear power accident, which is closely related to the national nuclear power production safety and people's life and property. The influence of the size change of cylindrical defect on burst pressure of inconel690 alloy heat transfer tube was studied by finite element simulation and experimental measurement. According to the simulation and test data, the relationship between burst pressure and damage parameter is established. The results show that for cylindrical defects with small depth, there is an extreme point of cylinder damage diameter b which makes the damage maximum, which makes the burst pressure at a minimum. The research results can provide reference for accurate evaluation of residual life of heat transfer tubes.

Recent Patents on Valve Mechanism Device

Background: Valves are an important part of nuclear power plants and are the control equipment used in nuclear power plants. It can change the cross-section of the passage and the flow direction of the medium and has the functions of diversion, cutoff, overflow, and the like. Due to the earthquake, the valve leaks, which will cause a major nuclear accident, endangering people's lives and safety. Objective: The purpose of this study is to synthesize the existing valve devices, summarize and analyze the advantages and disadvantages of various devices from many literatures and patents, and solve some problems of existing valves. Methods: This article summarizes various patents of nuclear-grade valve devices and recent research progress. From the valve structure device, transmission device, a detection device, and finally to the valve test, the advantages and disadvantages of the valve are comprehensively analyzed. Results: By summarizing the characteristics of a large number of valve devices, and analyzing some problems existing in the valves, the outlook for the research and design of nuclear power valves was made, and the planning of the national nuclear power strategic goals and energy security were planned. Conclusion: Valve damage can cause serious safety accidents. The most common is valve leakage. Therefore, the safety and reliability of valves must be taken seriously. By improving the transmission of the valve, the problems of complicated valve structure and high cost are solved.

KERAGAAN KEDELAI (Glycine max (L) merril) GENERASI M1 VARIETAS ANJASMORO HASIL RADIASI SINAR GAMMA

The purpose of this research was to find out the diversity of Anjasmoro variety soybean of M1 generation resulted from gamma-ray radiation on its various phenotype characters. A total of 300 seeds were radiated with Isotope and Radiation Technology Application from National Nuclear Power Agency at Pasar Jumat, South Jakarta, then planted in the experimental garden of Agriculture Faculty, Riau University. The dosage of irradiation used was 100 Gy, 150 Gy, 200 Gy, and 250 Gy also M0 as an ancestor. The quantitative and qualitative observation was made as such flowering age, harvest age, plant height, amount of seeds per plant, seeds weight per plant and growth type. The data were analyzed with variance analysis then continued with Duncan’s New Multiple Range Test on a 5% level. The diversity component was analyzed with homogeneity of variance according to the Levene test procedure. The result shows gamma-ray radiation is causing diversity on Anjasmoro variety on quantitative characters such as flowering age, harvest age and seed weight per plant. The vast diversity has happened on irradiation dosage of 200Gy.

Possible scenarios of transition to the closed nuclear fuel cycle

This work is devoted to the comparative analysis of various scenarios of transition to introduction of the closed nuclear fuel cycle and sodium fast reactors in nuclear power of Russia. The analysis of the permissible scale of introduction of water-water power reactors and fast sodium reactors into the Russian nuclear power system was carried out taking into account the estimated reserves of natural uranium, the expected volumes of spent nuclear fuel from both national and foreign nuclear power plants and the quantity of plutonium available for the introduction of fast sodium reactors. The rate of growth in the capacity of the nuclear power system is not yet high, the resources of natural uranium seem significant, the natural uranium mining facilities and the amount of depleted uranium have not yet been classified as encumbrances. In the current situation, the practical solution to the problems of closing the nuclear fuel cycle and transition to the trajectory of development of nuclear energy as a system that meets in the future the requirements of sustainable development and energy security can already be started with the use of mixed uranium-plutonium oxide fuel in combination with fuel from enriched regenerated uranium in existing water-water power reactors and in BN-800. This step is the most promising in terms of minimizing contradictions between the existing legal and institutional framework, allowing the development of closed fuel cycle technology and reducing the amount of spent nuclear fuel. Based on the assessment of the technical and economic characteristics of various scenarios for the long-term development of the two- component nuclear power system in Russia, several possibilities for reducing the cost of implementing the transition stage from open to closed nuclear fuel cycle.

Analysis on the trading mode suitable for nuclear power in power market

The energy crisis in the 21st century has become the most imperative problem to be solved by human beings. Nuclear energy is a vital base-charge power supply, which has high security, clean function and high efficiency. With the gradual development of nuclear power, the power is participating in the direct trading of the electricity market step by step. However, the rules of direct trading in China is not relatively complete, which leads to the unreasonable decline of the economy of nuclear power units. And there are drawbacks in the adjustment of energy structure, which also has a negative impact on energy conservation and emission reduction. So the author analyzes the current national nuclear power policies and electricity price costs, and proposes the current problems faced by nuclear power in direct electricity market and provides the basic directions and ideas for solving measures to help nuclear power better participate in direct electricity trading.

Аналіз проблем розвитку атомної, теплової та відновлюваної енергетики в енергосистемі України

In order to research the process of development of the energy systems of Ukraine, the current status and problems of development of nuclear, thermal and renewable energy are analyzed. The global trends in the development of nuclear energy is identified and it is noted that after the short-term decline caused by the accident at the «Fukushima-1» nuclear power plant, a gradual increase in the number of operating reactors has begun. The crisis situation in the nuclear and thermal energy market is outlined. Within the framework of the existing PSO (Public Service Obligation) model, the National nuclear power generating company «Energoatom» suffers significant losses. The limitation of electrical energy production at nuclear power plants in 2020 is an insufficiently grounded measure that will adversely affect the energy security of the country. Shutting down the power units of nuclear plants means that instead of producing energy one begins to consume energy, while a constant duty with ongoing servicing of equipment and maintaining the security systems is required. It is indicated that the coal-fired power plants of Ukraine have already developed their estimated resource and have an extremely low usage rate of installed capacity. In addition, coal-fired power plants in Ukraine are used in maneuvering modes, to cover peak loads, which leads to accelerated wear and tear of equipment and reduces production efficiency. A comparative analysis of the development of renewable energy sources (RES) is carried out and it is proved that the increase in electrical energy production due to RES requires the development of sufficient maneuvering capacities. The current situation indicates that the capacities of HPP and PHES are not sufficient, so at this time coal-fired power plants are used for such purposes, but such a part-time mode of operation leads to further wear and tear of equipment and an increase in emergency situations.

Nuclear Power Plants and Terror Attacks in Japan

The operation of several Japanese nuclear power plants has been halted because the Nuclear Regulatory Committee (NRC) reported that these nuclear power plants are not sufficiently prepared for potential terror attacks. It is unclear how the Japanese judiciary exercises judicial review for this NRC decision regarding terror attack protection measures. Japanese courts previously avoided the constitutionality of defense and peace statutes by using political questions. The attitude of the Japanese judiciary toward national defense is symbolic in several cases for Article 9, the pacifism provision of the Japanese constitution. Japanese administrative agencies are authorized to exercise discretion in the scope of power that is vested in them by the statutes passed in the parliament, or Diet. Under the Administrative Case Litigation Act (ACLA), which was revised in 2004, Japanese courts can review administrative discretion according to several principles such as fact-finding, purpose, timing, equal principles, constitutional rights infringement, and unconstitutional motives. The Judiciary has reviewed administrative agencies’ decision under under ACLA. Under ACLA, Japanese courts maintain arbitrary and capricious administrative discretion but not the political validity and policy judgement capability of administrative agencies. Judiciary defers to administrative agency decisions for its expertise. Citizens may take action toward administrative agencies regarding its validity by the Administrative Appeal Act (AAA). The AAA provides an avenue that is simpler than ACLA and yields a more rapid response, but it is not as fair as the ACLA because agencies themselves conduct an internal review on the validity of its decisions. In the famous Ikata nuclear power plant case of 1992, the Japanese Supreme Court deferred to the administrative agency decision for its expertise but did not use the term “discretion.” This may have been because nuclear power plants are related to Japanese energy policy, thus affecting Japan as a whole. This paper argues that in general, the judiciary does not thoroughly review public records and the reasoning behind administrative decisions but may identify unconstitutional motives. The Japanese court has not yet reviewed the NRC decision of halting nuclear power plant operation due to possible terror attacks. The statute for terror attacks was passed soon after the Great East Japan Earthquake in 2011. Terror attacks may provide an avenue for the Japanese judiciary to avoid conducting a judicial review of the administrative agency’s decision. It is unclear whether the Japanese judiciary will carefully examine this issue or defer to the NRC as terrorist protection overlaps with the field of national defense, which is stipulated in Article 9. This paper argues that national defense and nuclear power plant safety in the event of natural disasters both differ and overlap. Japanese administrative law scholars must analyze the expertise of the administrative agency in giving deference to the Japanese judiciary.

Пріоритетні напрями довгострокового розвитку національної атомної енергетики

We established that the formation of prospects of the development of national nuclear power depends, first of all, on such key factors as the term of extension of the service life of existing NPP units, the hardness of regime constraint on their operation in an energy system, and system-wide economic efficiency and environmental friendliness of a certain structure of generating capacities in the United Power System of Ukraine. We carried out an analysis of the current state of implementation of new light-water reactors of high power and promising small modular reactors. Based on the estimates of prospects of the implementation of new nuclear power units, obtained by using the mathematical model of long-term forecasting the development of structure of generating capacities in the power system, taking into account the need to replace operating NPPs, we determined the priority areas of long-term development of national nuclear power. In the formation of decisions concerning the introduction of new power units, it is quite important to take into account the dynamics of their commission and decommission with regard for their operation life and unit capacity at the projected growth of demand for electrical energy. It has been established that, in the case of hardening the requirements to carbon-intensity of electricity, including an increase in the CO2 emissions charge, it is advisable, instead of construction of new coal-fired power units of TPPs in the period 2036–2040, to increase the capacity of NPPs, including the introduction of maneuvering units with small modular reactors as a low-carbon source of electricity production with enhanced operational safety to ensure sustainability, reliability, and efficiency of the functioning of Ukrainian UPS. We also determined the feasibility of replacing existing nuclear power units that are decommissioning by new advanced third-generation powerful nuclear power units.

Analytical Design of Helical Coil Steam Generator for Hot Temperature Gas Reactor

Reaktor Daya Eksperimental (RDE) is a non-commercial Hot Temperature Gas Reactor (HTGR) which is currently being developed by National Nuclear Power Agency of Indonesia (BATAN). Integrated helical coil steam generator attached in the RDE is selected to generate 10 MW steam. In order to achieve the rated power, steam pressure of 62 bar, steam temperature of 798.15K and mass flowrate of 3.54 kg/s are required as the output parameters to be produced by the steam generator. A compact design of a once through counter-flow helical coil steam generator is proposed. Analytical design of the helical coil steam generator is conducted to check the heat transfer area required to achieve the rated power. A simple thermodynamic analysis combined with empirical heat transfer coefficient for convective and boiling process inside the steam generator at constant pressure was performed. It is shown that with inlet water temperature of 418.15K and helium gas inlet of 973.15K at 4.27 kg/s and 34.2 bar as the heating fluid produced output helium gas temperature of 511.42K. Based on comparison with available similar existing HTGR reactor, the calculation overestimate heat transfer surface area by around 20%. Hence, the required area to achieve the rated power for the proposed design is estimated around 60.2-75.3 m2.

A new “nuclear normalcy”?

This article focuses on a part of the “nuclear condition” that is often overlooked in philosophical discussions: that of materiality. Connecting the spheres of nuclear weapons (and associated security threats), and of nuclear power generation (and associated safety concerns), are the materials that bombs and electricity can be made of, and the machines that produce either enriched uranium or plutonium. We now have evidence of just how fragile the machines and devices were (and are) that sustained the nuclear age, but also how tenuous and artificial the boundary is that we assume between “peaceful” and “military” purposes. And yet, each new “nuclear deal” affirms this boundary, and the possibility of its existence. While the community of scholars and policymakers who prioritize nuclear security strive to label as many steps of the process as “special,” and therefore subject to inspection, accounting, and international control, multinational power companies and national nuclear industries promote “technical fixes” for lingering safety concerns, and advance the opposite strategy: to “normalize” many processes to the point of including severe accident response into the industry’s business-as-usual. The article argues that different kinds of “nuclearities” have increasingly become accepted as “normal”: on one hand, international diplomacy that foregrounds legal and regulatory strategies to nip potential nuclear weapons programs in the bud, and on the other, national nuclear power programs growing their fleets and attempting to expand their market reach. By accepting the divide between the “security community” and the “safety community” as the new “nuclear normalcy,” the shared nuclear materiality threatens to slip out of view, or at the very least, out of focus.