Wu 2016a - Revision history

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Scipediacontent at 07:08, 7 April 2017

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Scipediacontent: Scipediacontent moved page Draft Content 308819135 to Wu 2016a

2017-04-06T13:25:08Z

Scipediacontent moved page Draft Content 308819135 to Wu 2016a

Scipediacontent: Created page with "====ABSTRACT==== In 2011, the Chinese Academy of Sciences launched an engineering project to develop an accelerator-driven subcritical system (ADS) for nuclear waste transmut..."

2017-04-06T13:23:13Z

Created page with "====ABSTRACT==== In 2011, the Chinese Academy of Sciences launched an engineering project to develop an accelerator-driven subcritical system (ADS) for nuclear waste transmut..."

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 |}
-[[#fig1|Fig. 1]]  shows the overall 3D view of CLEAR-I. The reactor core consists of fuel, shielding, and inner-to-outer reflector assembly in the radial direction. In addition, 8 control rods are configured at specified positions, shown in [[#fig2|Fig. 2]] . Each fuel assembly (FA) is surrounded by a hexagon wrapper containing 61 pins. Each pin is circular in its horizontal section and fixed with helical wire-wrap. To ensure the FA stability, the padding is set in the neighbor FAs, and is weight-counted in vertical. The core is loaded with 86 FAs, and the active zone of the core is 800 mm in height and 1230 mm in diameter. The reactor core is designed in both subcritical and critical conditions, shown in [[#fig2|Fig. 2]] . The initial ''k''<sub>eff</sub>  in critical mode at the beginning of life (BOL) is 1.016; after 10 years of operation, it will decrease to 1.008, with the average fuel burnup being 10.195 MW<sub>d</sub>  per kilogram U. The neutronics analysis of the core is performed with the Super Monte Carlo Simulation Program for Nuclear and Radiation Process (SuperMC) [[[#bib14|14]] ]. During operation, results show that the reactivity coefficients, such as the temperature coefficients and expansion coefficients, are negative. The reactivity is controlled with two independent control systems during operation, both of which satisfy the stuck rod criterion and ensure that the core can be shut down safely.
+[[#fig1|Fig. 1]]  shows the overall 3D view of CLEAR-I. The reactor core consists of fuel, shielding, and inner-to-outer reflector assembly in the radial direction. In addition, 8 control rods are configured at specified positions, shown in [[#fig2|Fig. 2]] . Each fuel assembly (FA) is surrounded by a hexagon wrapper containing 61 pins. Each pin is circular in its horizontal section and fixed with helical wire-wrap. To ensure the FA stability, the padding is set in the neighbor FAs, and is weight-counted in vertical. The core is loaded with 86 FAs, and the active zone of the core is 800 mm in height and 1230 mm in diameter. The reactor core is designed in both subcritical and critical conditions, shown in [[#fig2|Fig. 2]] . The initial ''k''<sub>eff</sub>  in critical mode at the beginning of life (BOL) is 1.016; after 10 years of operation, it will decrease to 1.008, with the average fuel burnup being 10.195 MW<sub>d</sub>  per kilogram U. The neutronics analysis of the core is performed with the Super Monte Carlo Simulation Program for Nuclear and Radiation Process (SuperMC) [ [[#bib14|14]] ]. During operation, results show that the reactivity coefficients, such as the temperature coefficients and expansion coefficients, are negative. The reactivity is controlled with two independent control systems during operation, both of which satisfy the stuck rod criterion and ensure that the core can be shut down safely.
 <span id='fig1'></span>

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 * Technology sustainability: UO<sub>2</sub>  has been adopted as the first loading fuel; advanced fuels (mixed oxide (MOX), transuranic (TRU), etc.) and MA-based fuels will be tested in later steps in order to validate the transmutation technology.
-Based on the above design principles, the innovative dual operation mode lead-bismuth research reactor CLEAR-I was designed and developed. Therefore, the ADS coupling test and the lead-based reactor critical operation test can be carried out in the same structural platform. Thus far, the detailed conceptual design of CLEAR-I is complete and the preliminary engineering design is underway. The LFR is one of the most promising concepts for Generation IV implementation based on GIF Technology Roadmap 2014, and due to its unique and innovative design features, CLEAR-I has been selected into the LFR catalogue by the International Atomic Energy Agency (IAEA) [[[#bib13|13]] ] and the GIF [[[#bib7|7]] ].
+Based on the above design principles, the innovative dual operation mode lead-bismuth research reactor CLEAR-I was designed and developed. Therefore, the ADS coupling test and the lead-based reactor critical operation test can be carried out in the same structural platform. Thus far, the detailed conceptual design of CLEAR-I is complete and the preliminary engineering design is underway. The LFR is one of the most promising concepts for Generation IV implementation based on GIF Technology Roadmap 2014, and due to its unique and innovative design features, CLEAR-I has been selected into the LFR catalogue by the International Atomic Energy Agency (IAEA) [ [[#bib13|13]] ] and the GIF [ [[#bib7|7]] ].
 ===3.2. Design description of CLEAR-I===

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 ==2. Technical characteristics and current status of the lead-based reactor==
-The lead-based fast reactor, which is one of the Generation IV nuclear systems, is considered to be the most promising reactor option for the ADS. According to the latest technology roadmap released by the Generation IV International Forum (GIF), the lead-cooled fast reactor (LFR) is expected to be the first demonstration and commercialization nuclear system of all the Generation IV systems [[[#bib7|7]] ]. The lead-based breeding (e.g., lithium-lead alloy) blanket is also being studied extensively for nuclear fusion reactor research around the world, due to its high heat removal, adequate tritium breeding ratio, relatively simple design, and potential attractiveness in terms of economy and safety.
+The lead-based fast reactor, which is one of the Generation IV nuclear systems, is considered to be the most promising reactor option for the ADS. According to the latest technology roadmap released by the Generation IV International Forum (GIF), the lead-cooled fast reactor (LFR) is expected to be the first demonstration and commercialization nuclear system of all the Generation IV systems [ [[#bib7|7]] ]. The lead-based breeding (e.g., lithium-lead alloy) blanket is also being studied extensively for nuclear fusion reactor research around the world, due to its high heat removal, adequate tritium breeding ratio, relatively simple design, and potential attractiveness in terms of economy and safety.
-Lead or lead alloy (lead-based) materials have low neutron absorption and moderation characteristics, resulting in good nuclear waste transmutation and fuel-breeding capability. Due to the low melting temperature and high boiling temperature of lead-based materials, a lead-based reactor can be operated under normal pressure, drastically lowering risks due to potential loss-of-coolant accidents (LOCAs) and increasing the electricity production efficiency. Fire and/or explosion risk issues can also be eliminated due to the chemical inertia of lead-based materials. Passive safety characteristics can be enhanced by passive decay heat removal, which is realized by the excellent heat and natural circulation capabilities of the coolant [[[#bib8|8]] ]. Thus, the lead-based reactor is considered to be the reference technology in most ADS programs around the world.
+Lead or lead alloy (lead-based) materials have low neutron absorption and moderation characteristics, resulting in good nuclear waste transmutation and fuel-breeding capability. Due to the low melting temperature and high boiling temperature of lead-based materials, a lead-based reactor can be operated under normal pressure, drastically lowering risks due to potential loss-of-coolant accidents (LOCAs) and increasing the electricity production efficiency. Fire and/or explosion risk issues can also be eliminated due to the chemical inertia of lead-based materials. Passive safety characteristics can be enhanced by passive decay heat removal, which is realized by the excellent heat and natural circulation capabilities of the coolant [ [[#bib8|8]] ]. Thus, the lead-based reactor is considered to be the reference technology in most ADS programs around the world.
-By taking advantage of this technologys relatively good technical maturity, excellent characteristics, and extensive and attractive application prospects for both fission and fusion energy systems, a number of lead-based reactor engineering projects are ongoing worldwide, such as the SVBR-100 [[[#bib9|9]] ] and BREST-OD-300 projects [[[#bib10|10]] ] in Russia, the MYRRHA ADS project [[[#bib11|11]] ] in Belgium, and the ELFR and ALFRED projects [[[#bib12|12]] ] in the European Union. Furthermore, various design and technology development activities are being conducted in the United States, Japan, and Korea.
+By taking advantage of this technologys relatively good technical maturity, excellent characteristics, and extensive and attractive application prospects for both fission and fusion energy systems, a number of lead-based reactor engineering projects are ongoing worldwide, such as the SVBR-100 [ [[#bib9|9]] ] and BREST-OD-300 projects [ [[#bib10|10]] ] in Russia, the MYRRHA ADS project [ [[#bib11|11]] ] in Belgium, and the ELFR and ALFRED projects [ [[#bib12|12]] ] in the European Union. Furthermore, various design and technology development activities are being conducted in the United States, Japan, and Korea.
 ==3. China lead-based research reactor (CLEAR-I)==

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 ==1. Introduction==
-An accelerator-driven subcritical system (ADS) is considered for construction in China to be an innovative nuclear power system due to its excellent capability for nuclear waste transmutation and its potential benefits for nuclear energy sustainability. In ADS, highly intensified and high-energy protons impinge on a heavy metal spallation target to produce spallation neutrons, which can interact with surrounding nuclear fuel in the reactor and keep the system operating in a subcritical state. Due to its features−a hard neutron spectrum, high neutron flux, and good capability for the transmutation of minor actinide (MA) and long-lived fission products (LLFPs)−the ADS has exhibited great superiority in achieving nuclear waste transmutation and energy multiplication. Moreover, it can significantly reduce potential radiological hazards caused by nuclear waste and improve the utilization of nuclear resources [[[#bib1|1]] ,[[#bib2|2]] ]. Based on these considerations, the Chinese Academy of Sciences (CAS) launched a Strategic Priority Research Program named the “Future Advanced Nuclear Fission Energy−ADS Transmutation System.” This program aims to develop and master all the key technologies of the ADS through three phases of research and development (R&D) [[[#bib3|3]] ].
+An accelerator-driven subcritical system (ADS) is considered for construction in China to be an innovative nuclear power system due to its excellent capability for nuclear waste transmutation and its potential benefits for nuclear energy sustainability. In ADS, highly intensified and high-energy protons impinge on a heavy metal spallation target to produce spallation neutrons, which can interact with surrounding nuclear fuel in the reactor and keep the system operating in a subcritical state. Due to its features−a hard neutron spectrum, high neutron flux, and good capability for the transmutation of minor actinide (MA) and long-lived fission products (LLFPs)−the ADS has exhibited great superiority in achieving nuclear waste transmutation and energy multiplication. Moreover, it can significantly reduce potential radiological hazards caused by nuclear waste and improve the utilization of nuclear resources [ [[#bib1|1]] ,[[#bib2|2]] ]. Based on these considerations, the Chinese Academy of Sciences (CAS) launched a Strategic Priority Research Program named the “Future Advanced Nuclear Fission Energy−ADS Transmutation System.” This program aims to develop and master all the key technologies of the ADS through three phases of research and development (R&D) [ [[#bib3|3]] ].
-In the first phase, an ADS research facility will be built, consisting of a proton accelerator, a heavy metal spallation target, and a subcritical reactor. The ADS research facility will adopt an accelerator design with a superconducting cavity and a superconducting magnet. Significant progress has been achieved to date in the development of the accelerator key components, such as an intense current proton source with high stability, the continuous wave (CW) proton radio frequency quadrupole (RFQ) cavity, and spoke cavity research. The general performance of the proton accelerator has reached the international standard, and some parameters have reached the international leading level. An innovative granular flow target has been proposed as the spallation target for the China ADS project [[[#bib4|4]] ]. It can sustain high proton beam power by transferring heat through granular flow. As a back-up option, the design and verification of a liquid lead-bismuth target with a window is pursued.
+In the first phase, an ADS research facility will be built, consisting of a proton accelerator, a heavy metal spallation target, and a subcritical reactor. The ADS research facility will adopt an accelerator design with a superconducting cavity and a superconducting magnet. Significant progress has been achieved to date in the development of the accelerator key components, such as an intense current proton source with high stability, the continuous wave (CW) proton radio frequency quadrupole (RFQ) cavity, and spoke cavity research. The general performance of the proton accelerator has reached the international standard, and some parameters have reached the international leading level. An innovative granular flow target has been proposed as the spallation target for the China ADS project [ [[#bib4|4]] ]. It can sustain high proton beam power by transferring heat through granular flow. As a back-up option, the design and verification of a liquid lead-bismuth target with a window is pursued.
-The China Lead-based Reactor (CLEAR) was selected as the reference reactor system; this system was proposed and developed by the Institute of Nuclear Energy Safety Technology (INEST)·FDS Team, CAS [[[#bib5|5]] ,[[#bib6|6]] ]. According to the development plan of the CAS ADS project, the reactor correspondingly consists of three phases, with the goals of developing a 10 MW<sub>th</sub>  lead-based research reactor, a 100 MW<sub>th</sub>  lead-based engineering demonstration reactor, and a 1000 MW<sub>th</sub>  lead-based commercial prototype reactor. During the first phase, a 10 MW lead-bismuth-cooled research reactor named CLEAR-I will be designed and built to carry out experiments on neutronics, thermal hydraulics, and safety characteristics. Moreover, the lead-based reactor technologies of construction, operation, control, and system coupling will be verified in the first phase.
+The China Lead-based Reactor (CLEAR) was selected as the reference reactor system; this system was proposed and developed by the Institute of Nuclear Energy Safety Technology (INEST)·FDS Team, CAS [ [[#bib5|5]] ,[[#bib6|6]] ]. According to the development plan of the CAS ADS project, the reactor correspondingly consists of three phases, with the goals of developing a 10 MW<sub>th</sub>  lead-based research reactor, a 100 MW<sub>th</sub>  lead-based engineering demonstration reactor, and a 1000 MW<sub>th</sub>  lead-based commercial prototype reactor. During the first phase, a 10 MW lead-bismuth-cooled research reactor named CLEAR-I will be designed and built to carry out experiments on neutronics, thermal hydraulics, and safety characteristics. Moreover, the lead-based reactor technologies of construction, operation, control, and system coupling will be verified in the first phase.
 This paper gives a brief introduction and description of the CLEAR-I reactor and presents the R&D progress on heavy liquid metal loops, key technologies and components, safety assessment, and environmental impact analysis. In Section 2, technical characteristics and current status of the lead-based reactor in the worldwide is briefly reviewed as the basis of this study. And in Section 3, the first phase of CLEAR is defined as CLEAR-I, and design characteristics and description are presented, i.e., design principles, design parameters, and structural components. Then in Section 4, R&D of key technologies and components of CLEAR are highlighted with three subsections. In the first subsection, multi-functional lead-bismuth loop KYLIN-II for material test is demonstrated, lead-bismuth eutectic (LBE) process technology, compatibility assessment of structural and cladding materials fuel assembly technology, and reactor key components are newly addressed for CLEAR, and in the last subsection integrated test facilities are introduced, including CLEAR-0 for zero-power research, CLEAR-S for pool-type integrated test, and CLEAR-V for reactor virtual simulation. Section 5 gives safety analysis and environmental impact assessment, and at the end the conclusions of this study are listed in Section 6.

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