Report by the Joint-Core Teamfor the Establishment of Technology Bases
Required for the Development of a Demonstration Fusion Reactor- Basic Concept of DEMO and Structure of Technological IssuesOriginal version in Japanese was issued on 18 July 2014
English version: 19 January, 2015
Agenda1. Introduction .......................................................................................................................... 2
2. On the Concept of DEMO Premised for Investigation ..................................................... 4
2-1. Change of Energy Situation and Social Requirement............................................. 5
2-2. Fundamental Strategy ................................................................................................ 6
2-3. Development Strategy ................................................................................................ 7
2-4. Basic Concept Required for DEMO ......................................................................... 8
2-5. Points of View for Changeover to DEMO Phase and Assessment of Transition
Conditions ................................................................................................................... 9
3. Technological Issues of Elements of DEMO .................................................................... 12
3-1. Superconducting Coils ............................................................................................. 13
3-2. Blanket ....................................................................................................................... 17
3-3. Divertor ..................................................................................................................... 21
3-4. Heating and Current Drive Systems ....................................................................... 24
3-5. Theory and Numerical Simulation Research ......................................................... 26
3-6. Reactor Plasma Research ........................................................................................ 29
3-7. Fuel Systems .............................................................................................................. 33
3-8. Material Development and Establishment of Codes and Standards ................... 36
3-9. Safety of DEMO and Safety Research .................................................................... 40
3-10． Availability and Maintainability ............................................................................. 42
3-11. Diagnostics and Control Systems ............................................................................ 45
3-12. Newly Required Facilities and Platforms............................................................... 48
4. Points of Reactor Design Activity...................................................................................... 48
5. International Cooperation and Collaboration ................................................................. 50
6. Summary ............................................................................................................................. 51

1

1. Introduction
Japanese fusion research and development is now in the phase targeting the achievement ofself-ignition condition and realization of long-pulse burn by the International Thermonuclear
Experimental Reactor (ITER) project, and the establishment of the technology base required for thedevelopment of a “DEMOnstration fusion reactor” (hereafter referred to as “DEMO”). This phase iscalled the Third Phase Program with the goal to show the scientific and technological feasibility offusion energy. And the present research and development is conducted in the framework of the “Third
Phase Basic Program of Fusion Research and Development” decided by the Atomic Energy
Commission (AEC) in June, 1992 [1]. In addition, specific guidelines aiming at the next Fourth Phase
Program with a core project of DEMO, which has the goal of technological demonstration andeconomic feasibility of fusion energy, have been shown in the “Future Fusion Research andDevelopment Strategy” [2] (hereafter referred to as “Future Fusion R&D”) determined by the AEC’s
Advisory Committee on Nuclear Fusion in Oct. 2005 which backed up the decision “Future Fusion
Research and Development Strategy in the Third Phase Basic Program of Fusion Research andDevelopment” by the AEC in November, 2005 [3].
Overseas, for example, Europe compiled “Fusion Electricity, A roadmap to the realization offusion energy” [4] in November, 2012 in order to clarify the way towards realization of fusion energy,
to stipulate priority fields on which the resources will be concentrated, and consequently to reorganize
the structure of fusion research and development in line with this new strategy. Like this movement,
among a major power, DEMO concept plans have been launched with taking into account the progressof the ITER project. The IAEA has established the DEMO program workshop from 2012 in responseto these developments [5].
After “Future Fusion R&D” was issued, the necessity to decide a strategic roadmap withclarification of technology which should be secured, maintained, and developed in Japan, to share thisroadmap among industry, government, and academia, and to activate a framework for implementation
throughout Japan has been noted in the reports “On Japanese Fusion Research and Development
Strategy Including ITER Project and Broader Approach” [6] (hereafter referred to as “BA”) in 2007
and “On Human Resource Development and Securement for Promotion of Fusion Research andDevelopment” [7] in 2008 by the Working Group on Fusion Research, the Nuclear Science andTechnology Committee, the Subdivision on R&D Planning and Evaluation, the Council for Scienceand Technology, the Ministry of Education, Culture, Sports, Science and Technology (hereafterreferred to as “MEXT”), and “Evaluation of the Basic Concepts of Approaches to the Fusion Researchand Development, Specified in the Framework for Nuclear Energy Policy, Etc.” [8] in 2009 by the
AEC’s Advisory Committee on Nuclear Fusion.
Then, the report “The Way Forward to Establish a Technological Basis for DEMO Reactor2

Development” [9] (hereafter referred to as the “the 6th Term Report”), which was issued in January,
2013 by the Working Group on Fusion Research, has noted that in order to proceed with posed mattersestablishment of the function to compose strategy for the development of DEMO with integrated
viewpoints is important. This function will be the core engine for the establishment of technology
bases for the development of DEMO. This report has also pointed out that this function is expected to
be formed through discussions by related people in the Fusion Energy Forum, the Japan Society of
Plasma Science and Nuclear Fusion Research, and other organizations in how the young generation inindustry, government, and academia who will be responsible for the future development of DEMO
will play important roles.
Under this comment, the Working Group on Fusion Research has requested, at the 37th meetingon 3 July 2013, the Fusion Research and Development Directorate, the Japan Atomic Energy Agency(hereafter referred to as “JAEA”), and the National Institute for Fusion Science (hereafter referred toas “NIFS”), which are implementing bodies of large projects, to take the leading role in forming thejoint-core team for the establishment of technology bases required for the development of DEMO.
The terms of reference of this joint-core team for the establishment of technology bases requiredfor development of DEMO defined by the Working Group on Fusion Research are as follows [10]:1. Mission
To develop strategy for the establishment of technology bases required for the development of
DEMO by taking into account the progress of the ITER project, the BA activities and academic
researches such as the Large Helical Device (LHD), and standing on the consensus in the Japanesefusion community.
2. Issues
1)

Concept of DEMO premised for investigation

2)

Activities requiring commitment and their goals (research activities, investigation activities)

3)

Scientific and technological review works for the above mentioned activities

3. Notes
1) To conduct wide cooperation and exchange with researchers and technological experts in industry,
government, and academia so as to stand on consensus in the Japanese fusion community. In
particular, expansion of cooperation and exchange between scientific societies is encouraged.
2) In order to refer a political deliberation to the Working Group on Fusion Research, a representativeof the joint-core team is requested to report on the status of activities routinely.
The Working Group on Fusion Research expects that the joint-core team will lead detailed
discussion about the strategy for the establishment of technology bases together with the Fusion
3

Energy Forum and the Fusion Network, and that prioritized scientific and technological issues areincorporated in international projects such as the BA activities and academic research programs, andthat consequently all endeavours are to organize a framework for implementation throughout Japan
towards the establishment of technology bases.
In accordance with the request by the Working Group on Fusion Research, the joint-core team,whose members are listed at the end of this report, has been launched and has worked out assigned
issues. The joint-core team has reviewed the analyses in “Future Fusion R&D” and other reports todate and has taken into account the most recent scientific and technological achievements and theirlatest prospects. Investigated strategy for the establishment of technology bases required for DEMO
has been reported as an interim report to show summary of issues at the 38th meeting of the Working
Group on Fusion Research (24 February 2014) [11] (hereafter referred to as the “Interim Report”).
Based upon the “Interim Report”, further analysis has been made by the joint-core team by taking
account of comments at the Working Group on Fusion Research and 7 explanatory meetings
throughout the country, and complied documentation has been reported at the 41st meeting of theWorking Group on Fusion Research (24 June 2014). This is the finalized report with revisions toreflect the comments at that meeting.
The Fusion Energy Forum examined DEMO development taking a tokamak as a case study due
to the request “Future regime towards realization of fusion energy” [12] (18 October 2007) by MEXT,
and submitted “Roadmap and Technological Strategy towards Commercialization of Fusion Energy”[13] and “Investigation Report on Human Resource Plan for Implementation of Development ofTokamak Demonstration Fusion Reactor” [14] in June, 2008. This present report has not shown adetailed timeline of the development plan, such as a roadmap as in “Roadmap and Technological
Strategy towards Commercialization of Fusion Energy.” However, it indicates critical points, such as
the Transition Conditions to the DEMO phase (the Fourth Phase Program), which are set based upon
the status of the ITER project, etc. And the present report has not closely analysed technological issues
in the form of the Working Break-down Structure (WBS) yet, though what a critical issue is in eachdevelopment field, how issues are linked with each other, and what the process to resolve the issue
should be analysed deeply. Also since the embodiment of the fundamental concept required for DEMO
has been examined in further depth, definition of some issues of development or the targets ofdevelopment would be different from the WBS defined in “Roadmap and Technological Strategy
towards Commercialization of Fusion Energy” in a variety fields, such as the divertor. The joint-coreteam plans to work out the detailed timeline of the development plan and a roadmap with WBS.

2. On the Concept of DEMO Premised for Investigation
The “Future Fusion R&D” documented discussions towards realization of fusion energy in terms4

of (1) basic approach, (2) development strategy, (3) consideration of development phases, (4) phasechangeover, (5) tokamak demonstration fusion reactor, and (6) check and review (hereafter referred as“C&R”), and proposed a concept of DEMO. The joint-core team has examined how a concept of
DEMO which will demonstrate power generation via fusion energy for the first time should be based
upon documentation in the “Future Fusion R&D”, the progress of other energy-related technology, andthe change of the social understanding of energy-resource demands and safety, as well as the progressof fusion research and development, and revised future prospects after the “Future Fusion R&D”.

2-1.

Change of Energy Situation and Social Requirement
Since 2005 when the AEC issued the “Future Fusion R&D”, there have been 3 major epochs thathave affected fusion research and development significantly. Those are the economic downturn
precipitated by the Lehman Brothers bankruptcy in 2008, the experience of the shortage of electric
power after the Great East Japan Earthquake, and the collapse of the nuclear safety myth due to theaccident at the Tokyo Electric Power Company Fukushima Daiichi Nuclear Power Station.
Although economic recession and shortage of electric power are temporal phenomena and are
expected to be recovered, the change in the general public attitude will be maintained for a long time.
Japanese people have recognized with pain that we can prioritize reduction of CO2 only under theconditions of a good economy and sufficiently available reserves electric power. Indeed, we must rely
on natural gas and oil to compensate for the shortage of electric power due to the suspension of all
nuclear power stations even if CO2 emission increases. The imported volume of natural gas has
increased by 18.4 million tons (26%) in 2012 compared with that in 2010. Consequently, a social
atmosphere that considered global warming a top priority has declined, and propaganda lacking
economic rationality such as “25% reduction compared with 1990” has been eclipsed.
The fundamental revision of atomic energy policy and the long-term suspension of all nuclear
power stations have reminded Japanese people of the reality that Japan does not yet have an alternativetechnology to replace fossil fuels even though Japan does not have a major domestic energy resource.
While renewable energy is fully expected, its limit is being recognized. Therefore, by considering thesecurity of domestic energy seriously, the importance of fusion research and development can be
stressed through general public opinion, and that technological innovation is a Japanese resource.
Commercialization of shale gas refers to a recent global change in energy resources. Shale gas is
produced now only in the United States and Canada, and this is the only area of demand that can beconnected by pipelines and where shale gas depresses gas prices at present. However, its deflationary
trend will propagate to LNG, which Japan imports. Thermal power generation by natural gas will thenbe a more attractive option than at present in terms of the unit price. There will be a possibility that the
supply and demand scenario for electric power in the late 21st century in Japan will develop based

5upon natural gas and coal. Since the thermal power generation by gas, which has good load following
capability, is preferable for co-prosperity with wind and solar power, its significant increase may befeasible. The Strategic Energy Plan decided by the Cabinet on 11 April 2014 [15] states that
dependence on nuclear power generation is reduced to the extent possible by promoting energy
conservation, and introducing renewable energy and improved thermal power stations. These
circumstances can be rephrased into the issue of how fusion energy is positioned in order to facilitate
the paradigm shift to fusion energy via high-efficiency thermal power from the base-load by nuclear
power. In this case, what is required for fusion energy would be the capability and the attractiveness toreplace thermal power generation, and the establishment of complementary relations with renewableenergy.
It is necessary to analyse seriously the effect of the collapse of the nuclear safety myth and a lossof national trust in science and technology in justifying DEMO directly connected to the realization offusion energy and to take an appropriate measures. It is known that a fusion reactor has intrinsic safety
features, such as no possibility of re-criticality and runaway. In addition, the potential hazard of tritium,
which is radioactive matter, in a fusion reactor is smaller by the third order of magnitude than thepotential hazard of iodine 131 equivalent in a fission reactor. It should be noted that construction of
DEMO in Japan would be difficult unless the design of DEMO shows safety beyond that of a nuclear
power station. The direction of fusion research and development should aim at commercializationconsistent with social demand by taking advantage of its safety.
Relationships between economic growth and CO2 emission are discussed here. There exists a
strong correlation between the growth of GDP and CO2 emission, and the reduction of CO2 emission
with simultaneous economic growth is impossible by the presently available technology. In case
expansion of electric power by nuclear power is difficult, the Japanese reduction target of CO2 in the
short and the medium terms should be defined to the low level. However, it is not reasonable to pay
attention only to CO2 emission from Japan because the Japanese CO2 emission is about only 4% of thetotal global amount. It is important to develop technological options to reduce CO2 globally in the very
long term. In this line, fusion research and development processes will benefit global society, and thereasons for their necessity are persuasive. Realization of fusion energy should be positioned as aninnovative technology to change the correlation between global economic growth and CO2 emission,and should be promoted with careful attention to economic rationality compared with othertechnologies to reduce CO2 emission.

2-2.

Fundamental Strategy
The goal in the promotion of research and development of fusion energy is acquisition of both

economic and social rationality competitive with other power generation based upon the fundamental
condition of scientific and technological feasibility so as to be commercialized. It is also necessary to6establish a design that takes advantage of intrinsic properties of high safety and to minimize
environmental load throughout the life cycle from construction to decommissioning.
With regard to the Transition Conditions of fusion R&D phases, the roadmap which defines
milestones in the research and development for DEMO should be elaborated following the anticipatedtime of the Intermediate C&R around 2020 and the Changeover toward the Fourth Phase Programaround 2027, both of which are described in the “Future Fusion R&D”.
Industrial, governmental, and academic sectors should cooperate with each other effectively sothat this fundamental strategy will be positioned appropriately in the grand policy, such as Strategic
Energy Plan, the Science and Technology Basic Plan, and others, by the government.

2-3.

Development Strategy
Fusion energy will have to have economic competitiveness including externality* among

diversified energy resources. This means that DEMO is required to demonstrate safety and operationalreliability.
Strategy to gain the support of public opinion about social rationality with regard to acceptance of
DEMO in addition to the economy is necessary. The design of DEMO which satisfies social request
and acceptance, as well as resolution of issues and technological integration to enable construction of
DEMO, is required. This means the necessity of reinforcement of a DEMO design team assembled bycompound and diversified talents.
The plan to define milestones toward its goal in the operational development phase of DEMO isimportant in order to resolve issues for commercialization.
Projecting the goal of DEMO, it is necessary to define the technological issues to fulfil theTransition Conditions towards the Fourth Phase Program first by a tokamak, which exhibits the mostadvanced development, and to approach defined issues by the organized framework for
implementation throughout Japan in parallel with the ITER project.
Implementation of the ITER project, which is an experimental reactor, is the central pillar in theactivity to establish the technology bases of DEMO. Therefore, all R&D programs in parallel with the
ITER project should consider synergy with it. In addition to reflecting achievements in the ITER
project, it is quite important to accumulate data which will contribute to resolution of technologicalissues of DEMO. For example, an R&D program aiming at reduction of the construction cost of
DEMO will be planned by making full use of the experience of the construction of ITER.

7

In order to promote acceleration and resolution by innovation and to incorporate a comprehensive
state of progress of fusion R&D at the Changeover to the Fourth Phase Program, complementary andalternative concepts, for example, a helical system and laser fusion to a tokamak, and, further,diversified R&D approach of innovative concept to realize breakthrough should be managed in goodbalance and in a strategically linked manner.
* Externality refers to indirect load and cost on environment by energy supply, and is distinguishedfrom directly visible cost (internal cost) such as fuel cost and construction cost, etc. This is also called
external cost. In the field of energy supply, it is a social and environmental cost that both supplier andconsumer cannot recognize directly. Since the external cost does not affect the price of energy in thecase that a specific regime such as CO2 emission tax is not incorporated, market principle does notwork in the external cost. Consequently, there is a danger that invisible social loss emerges.

2-4.

Basic Concept Required for DEMO
In view of the status of energy and social circumstances since the Great East Japan Earthquake,

the Japanese fusion community is requested to produce the plan to develop DEMO endowed withsafety which society requires and to show confidence in the commercialization of fusion energy by the
middle of the 21st century. The purpose of DEMO is to indicate the prospect to achieve economic andsocial rationality of fusion energy competitive with other energy resources.
The “Future Fusion R&D” stated that a tokamak DEMO is presumed to have dimensions similar
to ITER and a generating capacity of 1 million kilowatts. From the view of the presently available
technology bases and their future prospects, this definition should be revisited in the planning of theroadmap with defined milestones aimed at steady and stable power generation beyond several hundred
thousand kilowatts, availability reachable for commercialization, and overall tritium breeding to fulfil
self-sufficiency of fuels.
The operational development phase of DEMO before reaching the targets should be planned byclassifying the commissioning phase, the power-generation demonstration phase, and thedemonstration of economic feasibility phase, and defining milestones at each phase. And targets, suchas demonstration of power generation by the system equivalent to a commercial reactor, demonstrationof high energy gain factor, long-pulse and long-term operation which can be extrapolated to acommercial reactor, and development and demonstration of advanced technology to improve
economic performance, should be achieved in each corresponding phase (see Fig.1).
The target of “overall tritium breeding ratio (TBR) beyond 1 is required” documented in the“Future Fusion R&D” must be achieved. What “overall” means here should be discussed in detail andclarified.

8

Controllability of plasma, such as heat and particle control, and disruption avoidance should beestablished in order to reduce excessive load on plasma facing components and to enable stableburning in the long term.
By realizing a maintenance scenario which can be extended to a commercial reactor, DEMO
should be aimed at demonstration of availability enough for commercialization at its final phase.
Flexible design of reactor-core components is required in order to resolve issues such as thehigh-performance blanket and the improvement of divertor capability towards commercialization.
Although the divertor and the blanket are based upon technology obtained in the ITER project and the
ITER-TBM (Test Blanket Module) will be employed in the early phase of DEMO, careful attention
should be paid to performance extension by improvement for long life-time and high-efficiency energy
conversion based upon new knowledge obtained during the operation of DEMO.
Component development should be planned based upon the definition of technological
specification of heat and particle flux on the divertor, and neutron and heat flux on the first wall of theblanket.
Security of safety to suppress exposure of the public as well as the workers in a DEMO plant toas low as possible (ALARA) rationally is necessary.
The construction cost of DEMO should be at the acceptable level from the view of subsequentcommercialization.

2-5.

Points of View for Changeover to DEMO Phase and Assessment of Transition
Conditions
It is relevant to elaborate the plan of technological development with the presumption of thereview of Transition Conditions around 2027 when the fusion burning with deuterium and tritium (DTburning) fuels will be demonstrated in ITER. Here, it is necessary to embody the contents and criteria
of judgement by close examination of C&R items (planned) indicated in “Future Fusion R&D” (seeTable 1).
The “6th Term Report” stated, “The Working Group on Fusion Research continues to revise thereport by deepening discussion about the Transition Conditions to the DEMO phase.” In particular,when and how much the results of energy gain, long-pulse operation, and demonstration of blanket
function, etc. will be obtained in the ITER project are critical elements directly connected to theassessment at the Transition Conditions to the DEMO phase. Therefore, it is necessary to investigate
the appropriateness and the timeline of these critical elements by revisiting the original point of these9criteria.
Above all, “demonstration of maintenance of plasma with Q20 (for duration longer than about
several 100 s) and burn control in ITER” (here, Q is the fusion energy gain and defined by the ratio ofenergy released by fusion reaction to externally applied energy to reactor-core plasma) and“demonstration of non-inductive current drive plasma with Q5 (for duration longer than about 1,000s) in ITER” in the C&R items (planned) of the Transition Conditions to the DEMO phase arerequested to be discussed in the Working Group on Fusion Research and in other councils. In order toaddress re-definition of the C&R items, the fusion community should form common recognition so as
to provide rational answers to these questions. For the former item, the goal of ITER is defined as
Q=10 and a pulse length is linked with not only validation of performance of reactor-core plasma but
also demonstration of functions of breeding and collection of tritium, heat removal, and power
generation** in ITER-TBM. Since the latter item is planned in the later phase of the ITER project,should these specific Transition Conditions be replaced by integration of results from achievements
ITER, JT-60SA (Japan Atomic Energy Agency: JAEA) and numerical simulation instead earlier thanits full demonstration in ITER?
** Basically ITER-TBM’s are aimed at tritium breeding, and not at power generation. Nonetheless,the Japanese TBM plans to generate power even though it is a limited level since it can generate steam
because of the employment of water as coolant.
In that case, the Intermediate C&R, which is the milestone before the assessment of Transition
Conditions for the Phase Changeover, becomes more important than before. The “Future Fusion R&D”
stated, “This milestone is presumed around ten years after the establishment of the ITER Organization.”
While the examination in this present report endorses that the draft targets at the Intermediate C&R
described in the “Future Fusion R&D” are appropriate, the time should be presumed to be around
2020, when the first plasma of ITER is expected, since the assessment of achievements of construction
and development in the ITER project is crucial at the Intermediate C&R. Further embodiment oftargets and their assessment should then be prepared.
Full-scale engineering R&D towards construction of DEMO will be launched by the success in
the Changeover to the Fourth Phase Program. On the other hand, in case commercialization of fusionenergy in the middle of the 21st century is aimed at, the start of engineering R&D at the proper level inthe preparation term before the assessment of the Transition Conditions should be promoted for early
realization of DEMO.
The significance of the statement “In deciding the Changeover to DEMO phase, it is important togain the prospect for its commercialization and to get the participation by private sectors, as well as tounderstand the overall progress of fusion research and development including other methods” in the10

“Future Fusion R&D” should be explored and embodied in succession.
Table I

C&R Items in future fusion R&D (draft)from “Future Fusion Research and Development” The Atomic Energy Commission’s Advisory
Committee on Nuclear Fusion, October 2005
Performance goal by check andTransition conditions

review in the interim phaseto the DEMO phase

1. Demonstration of burn

 Lay out plans for achieving the Demonstration of maintenance ofcontrol in self-heating

technological goals of experimental

plasma with Q20 (for duration

regime using

reactor based upon the actual ITER

longer than about several 100 s)

Issuesand burn control in ITER

experimental reactor
2. Realization of Lay out plans for achieving the Demonstration of non-inductive

non-inductive

goals based upon the actual ITER

current drive plasma with Q5 (forduration longer than about 1,000 s)

steady-state operation
with Q5 using
experimental reactor
3. Establishment of Complete ITER facilities

 Establishment of integration

integration technology

 Acquire integration technology

technology through the operation

using experimental

related to manufacturing,and maintenance of ITER.

reactorinstallation, and adjustment ofVerification of safety technology

components
4, Establishment of Conduct ITER support research Attainment of sustaining

high-beta steady-stateand preparatory research for

high-beta (n=3.5-5.5) plasma inoperation method tohigh-beta steady-state plasma andcollision-less regime in National

obtain economicallaunch research using National

Centralized Tokamak.

prospects

Centralized Tokamak

5. Development of Complete establishing Demonstration of tritiummaterials and fusion

technological basis for power

breeding and recovery functions,

technologies related togeneration blanket. Complete

removal of heat and power

DEMO reactor

manufacturing test components togenerating blanket in a low-fluence

be used in the functional test of

DT experiment on ITER

ITER

 Completion of verification of Acquire reactor irradiation data ofheavy irradiation data of reduced

reduced activation ferritic steels up

activation ferritic steels up to a

to 80dpa and determine testlevel of 80 dpa

materials to be used in theirradiation test under neutron11

irradiation environment similar tothat of fusion reactor
6. Conceptual design of  Determine the overall goal of Completion of conceptual design

DEMO

DEMO

of DEMO consistent with the Conduct preliminary work on thedevelopment of fusion plasma

conceptual design of DEMO

research and fusion technology

 Make requests for the required
development of fusion plasma
research and fusion technology

3.

Technological Issues of Elements of DEMO
In accordance with the “6th Term Report”, technological issues of elements of DEMO are sorted

into the following 11 categories.
(1)

Superconducting Coils(2)

Blanket(3)

Divertor(4)

Heating and Current Drive Systems(5)

Theory and Numerical Simulation Research(6)

Reactor Plasma Research(7)

Fuel Systems(8)

Material Development and Establishment of Codes and Standards(9)

Safety of DEMO and Safety Research(10) Availability and Maintainability(11) Diagnostics and Control Systems
Then, each element has been analysed in order to clarify the procedure to demonstrate thetechnological feasibility of DEMO, which is the most fundamental base, and to develop the roadmap
with the timeline and implementing bodies.
Analysis has been done in line with the following procedure and remarks based upon “Issues” and“ Measure and Managing System Required for Resolution” documented in the “6th Term Report”.
1) To reconfirm the documentation pointed out in the “6th Term Report”.
2) To analyse issues from the points of rearrangement, extraction of a core issue, prioritization andclarification of the reason of prioritization, etc. Then, to show the structure (tree) of
technological issues in each element in view of the timeline with the Intermediate C&R and the12assessment of the Transition Conditions presumed around 2020 and 2027, respectively.
3) To define the packaged measure consisting of “Concern” which prevents development/evolution,in other words, necessary conditions to move forward, “Defined Issue” in order to resolve
concern, and “Implementing body/Platform” which is charged with Defined Issue.
4) This packaged measure consisting of 3 elements can be understood as a project. To sort out thelinkage between these packages and to align these packages with each other logically.
5) To document the presently ongoing projects such as the ITER project and the BA activities aswell in the form of the above mentioned packages.
6) To pursue the main stream in order to ensure sufficient feasibility and to contrast the side stream
which plays a complementary role and is expected to innovate breakthroughs.
7) To show interaction between the projects described by the package and interface with otherelements and the DEMO design.
8) To show implementing bodies/platforms corresponding to defined issues in a table. Those whichplay a major essential role, those which play an important role, and those which can make alimited contribution are described by , , and , respectively. These tables indicate what canbe dealt with by the presently ongoing projects and existing implementing bodies/platforms ortheir expansion/reinforcement, as well as what are not yet dealt with because of lack ofcorresponding projects and implementing bodies. The ITER project and the BA activities are thecore in the presently ongoing projects. JT-60SA, which is a part of the BA activities, isdescribed separately.
9) In the figures and the tables, the Japan Atomic Energy Agency, the National Institute for Fusion
Science, and the National Institute for Materials Science are abbreviated as JAEA, NIFS, andNIMS, respectively.
The following items are indicated based upon the above mentioned analysis of the structure oftechnological issues, aligned R&D with defined milestones, and plans of research bodies grapplingwith issues and required facilities.
1) What is required before the Intermediate C&R
2) What is required after the Intermediate C&R and before the assessment of Transition Conditions(driving the content mentioned as “Promotion to start the enterprise of engineering R&D inaccordance of the assessment at the Intermediate C&R” in section 2.5).
3) Urgent issues4) Points of note

3-1.

Superconducting Coils

1) Technological issues, and measures and the management systems required for resolution, whichhave been indicated in the “6th Term Report,” are summarized as follows below.

131-1) Issues(a) Improvement of strength of structural material. High strengthening of the conductor and its
electrical insulation against high mechanical stress.
(b) Improvement of critical current density (Jc) and mechanical strength of the superconductor strand.
Improvement of the mechanical strength of the coil as a whole system. Mitigation of degradationof Jc caused by the residual strain due to the difference of thermal contraction between the strand
and the conduit of the CIC conductor and/or by the bending stress at mutual contact points of
strands in the twisted cable.
(c) Nb3Sn: Improvement of the structure of the CIC conductor or development of an innovative
conductor in order to mitigate the degradation of Jc due to the large electromagnetic force.
Investigation of measures for reduction of AC loss and stability improvement, and a scheme ofcooling for the coil.
(d) Nb3Al: Further lengthening of the strand and the reduction of the cost of the strand. Improvementof the current rating of the conductor.
(e) ReBCO: Further lengthening of the strand and the reduction of the cost of the strand.
Minimization of used amount of silver. Other issues include structure of the conductor and thescheme for twisting to enlarge current rating, mechanical reinforcement, cooling scheme, quench
protection, reduction of AC loss, and technology of joint and winding.
(f) Full-scale conductor test facility which can provide the field conditions required for DEMO must
be prepared. Establishment of a conductor test method which can evaluate the degradation of
performance due to electromagnetic force.
(g) Development of innovative superconducting materials and investigation to enable assessment of
their practical utilization and mass production.
1-2) Measures and Management Systems Required for Resolution(a) Towards accomplishment of the targeted performance, implement selection of materials fromvariety of candidates efficiently in a framework including universities, industries, and othercontributors throughout Japan.
(b) Vigorously promote improvement of the mechanical property of the Nb3Sn conductor anddevelopment of high performance Nb3Al conductor in parallel and in a competitive manner.
Develop the high temperature superconductor in a long-term strategy. Review technologies
developed for ITER construction in terms of their application to DEMO. And compose a concrete
R&D plan in the areas where further evolution and/or innovation are necessary with aconsideration for human resource development and implement this steadily.
(c) Quickly implement a development plan to improve Jc of the Nb3Sn conductor at higher magnetic
field into concrete shape and promote the planned action under appropriate role sharing among
universities, national institutes and industries while also utilizing international cooperation(d) With regard to rapid heating and quenching of the Nb3Al conductor, develop a large current
14conductor and demonstrate its applicability to DEMO through the R&D coil test undercollaboration between JAEA and the National Institute for Material Science (NIMS). Based upon
the demonstration, the development plan to enable industrial production capability in industries isrequired.
(e) R&D on ReBCO is in progress for its application to high field magnets and power equipment
such as a motor. Since a large current conductor, however, is specific for magnetic fusion
application, the strategy of development and the concrete plan should be identified in the context
of DEMO R&D.
(f) Maintain and upgrade existing conductor test facilities at JAEA and NIFS, and establish thescheme for conductor tests.
(g) Mature theoretical and numerical simulation methodology in order to document microscopic
electromagnetic phenomena in a superconductor and its macroscopic properties. Establish aframework to enhance mutual exchange of information or personnel between and among otherfields, and between and among government, academia, and industry.
2) Analysis of Issues2-1) Sorting-out Issues
Unfolding issue (b) in 1-1), it has common elements in issues (a), (c), (d) and (e). Issues (f) and(g) are concerned with the infrastructure to tackle issues (c), (d) and (e). On the other hand, outcomesfrom the DEMO study in BA imply that some requirements for superconducting coils, maximum
magnetic field of 16T at TFC, for example, which have been premises of those issues might bemodified through design harmonization across the entire system. Also manufacturing with a toleranceof 1/10000 required for the TFC of ITER might be a limit of accuracy in manufacturing a large
component from industry’s point of view.
Taking account of the argument above, the structure of the issues in Superconducting Coils isarranged in Fig. 2. Sectors in charge and necessary facilities, which are described in Fig. 2, aresummarized in Table 2.
2-2) Extraction of Core Issues
Construction of ITER and of JT-60SA are now in progress. Both of these devices are large
superconducting coil systems which will move beyond preceding machines and demonstrate thesignificant progress in mass production of high performance strands and conductors, and in the
manufacturing of huge coils from conventional technologies. It is extremely important to accomplish
manufacturing of the components and construction of the system, and to reflect the lessons learned
through this process in the design of DEMO.
Based upon the structure of the issues, which is shown in Fig. 2, the prioritized core issues
addressed in Superconducting Coils are summarized as follows below.
15

What are necessary tasks before the Intermediate C&R ?
 It is necessary to reconsider and clarify the specification requirements for the superconducting coilsystem in harmony with the overall DEMO design.
 Pre-conceptual design of the superconducting coil system based upon the above requirements isrequired.
 It is necessary to review the issues based upon the outcomes of the pre-conceptual design anddecide the R&D strategy for the superconducting coil system.
What are necessary tasks after the Intermediate C&R and before the assessment of the Transition
Conditions ?
 It is necessary to implement actions to accomplish the targets for Jc of the Nb3Sn strand, highstrength structural materials development, insulation materials development, and conductor
performance improvement which are defined in the R&D strategy
 The conceptual design of the superconducting coil system is necessary.
 Final selection of materials based upon the outcomes of the conceptual design and material
development is necessary.
Urgent issues
 The DEMO design team should be properly organized and strengthened. A design group for thesuperconducting coil system should be created within the DEMO design team, and pre-conceptual
design activity for superconducting coils should be initiated.
Points of note
 In order to review the technology issues described in the above and to decide the R&D strategy,
prospects in the development of structural materials, superconducting materials, and other materials
are necessary as input information. In particular, with regard to the Nb3Sn conductor, production
for ITER is in progress and verification of performance is under way. Data to be used fortechnological assessment of DEMO should be collected from evaluation of the margin in the ITER
design through a kind of performance limit test in addition to those tests to confirm theperformance specified for ITER. And it is necessary to pay attention to flexibility in the planningso as to enable feedback to the design of DEMO from the consequences of engineering R&D andthe experience of assembly and the initial operation of ITER
 Existing facilities should be upgraded in an appropriate timely manner in order to test conductors
and coils in higher magnetic field.
 It may not be easy to secure engineering staff in the design group for the superconducting coilsystem while manufacturing of the ITER coil and the construction of JT-60SA are proceeding inparallel. Staff should be increased step by step and a scheme should be planned to make the bestuse of human resources, including from universities.
16 Nb3Sn is a current prime candidate for the superconducting material. Nb3Al shows superior
performance at higher strain and is tolerable for use in a higher stress condition. High temperature
superconducting material (ReBCO) has a potential of higher Jc at higher magnetic field, higher
mechanical strength, and better cooling stability. These two alternative candidates should be
developed in parallel with Nb3Sn not only for adoption to DEMO but also for the prospect offurther performance improvement that is favourable for a commercial reactor. Collaboration with
their development for purposes other than fusion, including industrial application should be taken
into account.
 The structure of the issues shown in Fig. 2 is based upon design concepts in the present DEMO
study in BA. Additional technological issues will be encountered if an innovative magnetic field
configuration such as Super-X diverter is introduced.

3-2.

Blanket1) Technological issues, and measures and the management systems required for resolution, whichhave been indicated in the “6th Term Report”, are summarized as follows below.
1-1) Issues(a) Expansion of basic/reference data for structural materials, tritium breeding materials, and neutron
multiplication materials.
(b) Demonstration of integrated functions of blanket system in full fusion environment.
(c) Demonstration of overall tritium self-sufficiency in DEMO and efficient suppression of tritium
permeation.
(d) Development of concepts of remote handling maintenance, plant safety and standards/criteria
harmonized with the overall DEMO design.
(e) For advanced blanket concepts, solutions of issues specific to each concept are required.
1-2) Measures and Management Systems Required for Resolution(a) <Measure> Compile reference data of both structural and functional materials (including loading,irradiation, and corrosion effects, etc.) required for development of standards/criteria and safety
guidelines.
<Managing System> Develop the DEMO engineering database through integrated evaluation ofneutronic, thermo-structural, and tritium properties of in-vessel components by using an intensive
fusion neutron source.
(b) <Measure> Carry out steadily design and manufacturing of ITER-TBM based upon awater-cooled solid-breeder concept and confirm the fulfilment of the performance specifications
by the performance evaluation test required for the licensing safety review of ITER. And also
demonstrate compatibility with high magnetic field environment and soundness of response tochanging load and environment.

17

<Managing System> From the initial stage of development, close collaboration among
universities, research institutes, and industries is indispensable to develop a world standard.
Demonstration test under high-dose irradiation environment is required to assess neutron
irradiation effects.
(c) <Measure> Through the development of cooling, tritium measurement, and recovery systems for
ITER-TBM, demonstrate feasibility of overall tritium self-efficiency of DEMO undersustainable operational conditions and prevention of tritium permeation and release to theenvironment required for environmental safety and security of the amount of tritium in DEMO.
Also aim at demonstration of electric power generation even if its scale might be small.
(d) <Measure> With regard to the concept of remote handling maintenance, develop the system to beable to cope with trouble and accidents and verify the concept of safety security in fullmaintenance. Establish a blanket system to be able to secure safety and manage incidents. By
carrying out receiving of TBM irradiated in ITER, post-irradiation experiment and storage,
complete a database of the TBM program and verify the totalized handling technology of radio
isotopes through advancement of disassembling and treating technology of large-scale activatedcomponents for DEMO. With regard to establishment of codes and standards, seek rational codesand standards taking into account intrinsic safety features of DEMO.
(e) <Measure> With regard to liquid breeder blanket concepts, the database construction, operational
demonstration, and experimental and analytical investigation of accidental events should bepromoted for specific issues related to a high magnetic field, separate recovery of tritium and heat,composition and impurity control, control of solid-liquid interface, etc., by using separate and/or
integral coolant circulation systems. Development of operation systems to derive advantages ofliquid blanket systems is important. With regard to solid breeder blanket systems (He cooled),
future investigation is required by involving progress in structural material development and
R&D in other countries.
2) Analysis of Issues2-1) Sorting-out Issues○ Difficulty to sort out issues related to the blanket is attributed to the fact that the target of DEMO
has not been fully decided upon while the specification required for the blanket is directly linked
with the performance specification of DEMO.
○ Since necessary elemental technologies related to blanket development are already clear, definitionof quantified targets and confirmation of those consistencies are important to materialize and toaccelerate activities.
○ With regard to a water-cooled solid-breeder concept, it is necessary to carry out steadily design andmanufacturing of ITER-TBM. Early realization of integrated functional test facilities (heat load,
irradiation, and tritium behaviour) and demonstration test of performance using the facilities are
required.
○ With regard to advanced concepts, the development schedule should be arranged while maintaining
18

consistency with the development of the solid-breeder concept.
Taking account of the arguments above, the structure of the issues in Blanket is arranged in Fig. 3.
Sectors in charge and necessary facilities, which are described in Fig. 3, are summarized in Table 3.
2-2) Extraction of Core Issues
Since the issues of the extension of data as well as overall demonstration of function have been
identified, quantification of targets is important. With regard to advanced blanket concepts, relation
with technological issues and the development plan of a water-cooled solid-breeder blanket should bewell arranged.
Based upon the structure of the issues, which is shown in Fig. 3, the prioritized core issues
addressed in Blanket are summarized as follows below.
What are necessary tasks is before the Intermediate C&R ?
With regard to a water-cooled solid-breeder concept as the prime candidate, It is necessary to review functional test facilities for ITER-TBM and the DEMO blanket anddevelopment plan, and to package them in a project.
 Through the activities described above, it is necessary to complete technological bases of blanket
system including design and manufacturing technology of blanket, tritium handling and neutron
measurement, etc.
 Fabrication of ITER-TBM should be completed.
With regard to advanced blanket concepts,
 By proceeding from the R&D on elemental technologies to integrated tests using coolant
circulation loop systems simulating reactor conditions, the simultaneous demonstration of pluralfunctions and phenomena and the acquisition of fundamental design data should be promoted.
 Since the design investigation and the R&D on heat exchange and power generation methods are
considered insufficient, reinforcement of the activities is required.
What are necessary tasks after the Intermediate C&R and before the assessment of the Transition
Conditions ?
With regard to a water-cooled solid-breeder concept as the prime candidate, It is necessary to compile basic data in order to analyse results of ITER-TBM experiments.
Additionally, it is necessary to confirm tritium breeding and recovery functions by different
facilities from ITER to complement the limitation in ITER (e.g., pulsed operation).
 It is necessary to demonstrate tritium breeding and recovery functions, removal of heat and power
generation (see Points of note below) in a low-fluence DT experiment on ITER.
 It is necessary to get a prospect of the soundness of the blanket in the DEMO environment through19

irradiation tests in addition to the ITER-TBM experiments.
 It is necessary to review the target definition of DEMO-TBM and the development plan, toorganize programs, to select a concept of DEMO-TBM, and to conduct scheduled development.
With regard to advanced blanket concepts,
 Identification of issues, feedback regarding blanket conceptual designs, and evolution of R&D
must be promoted byseparate examination of technologies and designs for each of blanket

fabrication technology, dissimilar material welding, coolant flow through complicated channels,
and transfer and recovery of hydrogen and heat etc. by use of small test devices.
 Various blanket concepts are proposed and R&D activities of each concept are being developed.
Concepts to be prioritized in DEMO-TBM R&D activities should be selected by comparison of
preliminary proposed DEMO-TBM designs with heat exchange based upon

involvement ofacquired fundamental design data and developed technologies.
Urgent issues
With regard to a water-cooled solid-breeder concept as the prime candidate, Firstly, specification of DEMO should be clarified, and then corresponding requirements for theblanket system should be defined.
 Collaboration among universities, research institutes, and industries for the ITER-TBM
development and comprehensive performance test should be strengthened.
 Guidelines regarding pressure resistance capability of the blanket container should be clarified in
the early stage of the development because they are related to the guidelines to secure plant safety
and have a great impact on the structure of the blanket container.
 To enhance activities described above, the DEMO design team should be strengthened. It isnecessary that a team charged in development of elemental technologies participate in design
activity.
With regard to advanced blanket concepts,
 Enhancement of activities for design investigation and comparison of candidate blanket concepts
and heat exchange methods is required for the prioritization in the DEMO-TBM R&D.
Points of note It is necessary to pay careful attention to the relationship between the target of “Demonstration ofburn control” and the target of “Demonstration of power generation in blanket” defined inTransition Conditions to the DEMO phase. In particular it should be noted that plasma burning
time affects demonstration of the functional test of the blanket.

20

3-3.

Divertor

1) Technological issues, and measures and the management systems required for resolution, whichhave been indicated in the “6th Term Report,” are summarized as follows below.
1-1) Issues(a) Magnetic configurations and plasma operation (in particular, detachment) which reconcile theheat load and pumping capability(b) Materials development, which takes into account the tritium inventory and material degradation
due to the heat, particle and neutron load(c) Heat removal design for steady-state high heat flux(d) Identification of the boundary plasma conditions and establishment of the burning plasma
operation scenario which are compatible with the soundness, and the maintainability of thedivertor components
1-2) Measures and Management Systems Required for Resolution(a) Ensure the extrapolation reliability of the detachment plasma based upon the demonstration of thedetachment discharges in large-scale experiments and validation of the convincing theoreticalmodel by the experimental results.
(b) Build a framework and develop a research environment to acquire comprehensive knowledge ofthe plasma-wall interactions including tritium in terms of materials, surfaces, boundary plasmas,
diagnostics, and neutron irradiation effects(c) Select the cooling method based upon assessment of economy, safety of the entire the DEMO
reactor system and the divertor heat load. If it is necessary to choose a cooling method other thanwater-cooling, construct a framework of the basic and technological research and development as
early as practicable(d) Develop the integrated simulation code which can cover from the core plasma to the divertor
components
2) Analysis of Issues2-1) Sorting-out Issues○ With regard to the concern with the divertor heat-load, this cannot be solved in a simple way
because there are major gaps between required conditions and present technologies. It is necessary
to determine the acceptable compromises by optimizing both reduction of the heat-flux to thedivertor and improvement of the heat removal property of the divertor. Furthermore, degradation ofmaterial property is unavoidable due to the neutron irradiation of the reactor condition. In particular,
the lifetime of material has a great impact on the policy of maintenance of the facility.
○ Plasma facing components are a complex of the plasma facing materials and heat transfer materials.
It is important to select adequate materials based upon the overall performances of heat removal21

and the lifetime of the complex, in addition to merits and demerits of the individual material
properties.
○ Detachment discharge is indispensable for the mitigation of the divertor heat load, and it isnecessary to introduce impurity gas for the realization. Since reduction of the divertor particle flux
is expected as a consequence of detachment, there is concern that the impurity gas introduction will
be an obstacle to the burning due to impurity influx to the core plasma and reduction of thepumping efficiency. Divertor configuration and components is required to enable a balance among
the impurity behavior, particle pumping property, and the operating scenario in order to mitigate
divertor heat flux by means of detachment discharge.
Taking into account the argument above, the structure of the issues in Divertor is arranged in Fig.
4. Sectors in charge and necessary facilities, which are described in Fig. 4, are summarized in Table 4.
2-2) Extraction of the Core Issues
In order to realize a heat balance at the divertor, both (1) reduction of heat flux from the burning
plasma, and (2) improvement of the heat removal characteristics of the divertor components under theneutron irradiation conditions, are necessary. Furthermore, in order to realize a particle balance in theplasma vacuum vessel, (3) securing particle controllability (exhaust of the fuel and impurity) is
required. Since these issues have a contradictory dependence with each other, it is necessary to find aconsistent compromise.
Based upon the structure of the issues, which is shown in Fig. 4, the prioritized core issues
addressed in the Divertor are summarized as follows below.
What are necessary tasks before the Intermediate C&R ?
 It is necessary to address the review of the fusion output specification to match a heat flux whichenables a heat balance at the divertor.
 It is necessary to clarify physical phenomena to govern the operational conditions of the divertor,
namely, the width of the scrape off layer (SOL), elementary processes of plasma wall interactions(PWI), and other issues.
 It is necessary to formulate a modeling to describe the detachment discharges and to conduct
verification and validation of the model by the experiments in the existing devices in order tosecure an extrapolating reliability for DEMO.
 It is necessary to develop high-heat conducting materials, which can maintain the material
performance and lifetime even under the heavy neutron irradiation conditions. Since the material
properties have an impact on the fundamental basis of the reactor design, including themaintenance cycle, it is necessary to select the candidate materials at an early stage.
 Copper alloys are first candidates for the high-heat conducting materials from the viewpoint of thevery high thermal conductivity. However, determining the characteristics of the neutron irradiation
22

tolerance is an urgent issue. Since there is a very limited research activity related to this field, it isnecessary to launch a research and development program.
 The design of the pump remains insufficient, despite the fact that the secure particles exhaust
property is one of the most essential functions for particle control of a burning plasma. It isnecessary to clarify usage conditions of the pumps and to launch a research and development
program.
What are necessary tasks after the Intermediate C&R and before the assessment of the Transition
Conditions ?
 It is necessary to propose a divertor configuration and the operating scenario to realize
simultaneously both particle control property and heat removal property by advancing the
optimization of the divertor configuration in reactor design study, and then to prove the feasibilityof the developed scenarios in JT-60SA and other plasma devices.
 In order to secure the extrapolated reliability of the detachment discharge scenario, it is necessary
to develop a comprehensive simulation study in addition to the theoretical modeling of theelemental processes of the divertor.
 It is necessary to develop the pumps, which can be operated under the reactor conditions.
Urgent issues
 It is an extremely important issue to secure the heat and particle controllability at the divertor, inorder to satisfy the required performance of DEMO. Since the divertor design has a great impact
not only on the in-vessel components but also on the overall system design of DEMO including
coil arrangement, it is necessary to pursue this issue as early as possible. Therefore, the following
are urgent issues concerning divertor design, optimization of the divertor configuration, modelingof the detachment discharge, and study of the comprehensive integrated simulation of detachmentdischarge including core plasma.
 Specifications of the pumps have not been clarified yet. In order to launch the research anddevelopment program, it is necessary to initiate a conceptual design of the pumps as early as
possible. This issue will have a major impact on the divertor design.
 In order to deal with high-heat flux to the divertor properly, it is reasonable to use copper alloys
with high thermal conductivity. On the other hand, available copper alloys do not have sufficientmaterial properties against the neutron irradiation, and it is foreseen that the divertor components
will have to be replaced frequently. In order to reduce the exchange frequency of the divertor
components and to realize the acceptable availability factor of DEMO, it is an urgent issue tounderstand and to improve the properties of the tolerance to neutron irradiation.
Points of note
 Not only pursuing the performances of the constituent materials, but also overall assessment of thedivertor component is required to select the candidate materials for DEMO.
23 Development of an innovative divertor cooling system is fundamentally important towards
achieving highly efficient energy production in DEMO.

3-4.

Heating and Current Drive Systems

1) Technological issues, and measures and the management systems required for resolution, whichhave been indicated in the “6th Term Report,” are summarized as follows below.
1-1) Issues(a) Continuous reliable operation over one year (steady state, high system efficiency, neutron
irradiation-resistance).
(b) Neutral Beam Injector (NBI): development of the radio frequency (RF: Radio Frequency) ion
source, technological development of beam acceleration (1-2MeV) and development ofphoto-neutralizer).
(c) Electron Cyclotron resonant Heating (ECH): development of the fast variable frequency gyrotron(170-220GHz), development of the mirror-less waveguide-injector-type launcher system.
(d) Establishment of remote maintenance method.
1-2) Measures and Management Systems Required for Resolution(a) Construct a core test facility as a domestic joint project (by completion of ITER construction).
(b) NBI: Urgently initiate development of photo-neutralizer which requires innovative technology.
(c) ECH: Keep continuous development by utilizing existing facilities.
(d) Neutron irradiation resistance: Validate in ITER and promote neutron irradiation materials
examination, etc.
2) Analysis of Issues2-1) Sorting-out Issues○ NBI and ECH which are expected to be a main heating and current drive system in DEMO should
be examined. Major technological development of both NBI and ECH is an extension of ITER
technologies. Therefore, steady technological development in ITER is crucially important.
○ With regard to NBI, the new technology required for DEMO includes development of a Cs-free ion
source (development of electrode material with low work function), high efficiency neutralizer(high-efficiency plasma neutralizer or laser neutralizer), and neutron irradiation resistance(deflection and focusing technologies for MeV-class beam). In addition, accumulation of theoperating experience in ITER is crucially important. In particular, issues of irradiation effect on
beam acceleration should be sorted out and reflected in design.
○ With regard to ECH, the newly required technology for adapting DEMO includes increase of
frequency, development of fast variable frequency to dispense with a steerable mirror, improvementof

multiple-stage

energyrecoverytechnology,

24

and

developmentofamirror-lesswaveguide-injector-type launcher system for minimizing the occupied volume of in-vessel
components. In addition, accumulation of the operating experience in ITER is crucially important,and development of fast dual frequency technology should be steadily advanced in JT-60SA.
○ The significance of Lower Hybrid (LH) and Ion Cyclotron Resonance (IC) in terms of the R&D for
DEMO should be clarified because of their major issues for adapting DEMO on the heat load onlauncher and antenna, and the plasma-coupling characteristics.
Taking account of the argument above, the structure of the issues in Heating and Current Drive
System is arranged in Fig. 5. Sectors in charge and necessary facilities, which are described in Fig. 5,
are summarized in Table 5.
2-2) Extraction of Core Issues
Since the heating and current drive systems for DEMO are an extension of ITER technologies,
steady progress in the ITER project is critically important, and accumulation of operating experience in
ITER and JT-60SA also is important. Core issues in the technological development for DEMO are

improvement of system efficiency and steady-state operation, and the minimization of the occupied
volume to ensure sufficient TBR.
Based upon the structure of the issues, which is shown in Fig. 5, the prioritized core issues
addressed in Heating and Current Drive System are summarized as follows.
What are necessary tasks before the Intermediate C&R ?
 It is necessary to get a prospect for development of NBI and ECH systems in ITER towards
extended development to enable these systems which are foreseeable from ITER technologies for
DEMO.
 It is necessary to clarify the roles and the power ratio of NBI and ECH in DEMO, and to develop
their R&D plans by focusing the technological specifications of the heating and current drive
systems
What are necessary tasks after the Intermediate C&R and before the assessment of the Transition
Conditions ?
 It is necessary to establish the beam focusing technology required for installing the neutron shieldstructure in the beam line in order to avoid performance degradation of the ion source by neutron
streaming from the beam line.
 It is necessary to develop the high-efficiency neutralizer for improvement of the efficiency of NBI.
 It is necessary to develop the electrode material with low work function for establishment of theCs-free ion source which enables steady-state operation.

 It is necessary to develop the multiple-stage energy recovery technology for improvement of theefficiency of the gyrotron for ECH
25

 It is necessary to develop the mirror-less waveguide-injector-type launcher and technology for fastvariable frequency for minimizing the occupied volume of in-vessel components to secure the breedingblanket space in order to avoid degradation of the total TBR.

 It is necessary to develop the gyrotron with higher frequency consistent with the DEMO design
since the magnetic field of DEMO is higher than that of ITER.
Urgent issues
 The R&D in ITER should be advanced steadily and the, R&D plan for DEMO should be developed
by defining the roles of NBI and ECH required for DEMO and their technological specification as
technological targets.
Points of note
 The mock-up test facility for DEMO NBI should be ready around the assessment of Transition
Conditions. It is necessary to establish planning and a framework including the decision whether
the test facility is newly constructed in Japan or an international project by extending the ITERNBTF (in Padova Italy).
 The neutron irradiation test facility for the equipment of NBI and ECH systems is necessary.

3-5.

Theory and Numerical Simulation Research

1) Technological issues, and measures and the management systems required for resolution, whichhave been indicated in the “6th Term Report,” are summarized as follows below.
1-1) Issues(a) Understanding of physical mechanisms for transport barrier, density limit, beta limit etc.
(b) Development of an integrated fusion plasma simulation code which is internationallycompetitive and highly reliable, and dedicated validation of its prediction capability based uponcomparisons with experimental results.
(c) Development of a system code for a fusion reactor taking account of spatial profiles of various
physical parameters in fusion plasmas and their temporal evolutions due to transport phenomena
and instabilities.
(d) Development of an integrated reactor engineering code including an integrated blanket analysis
and a material analysis.
(e) Development of a simulator integrating items described in (b)-(d).
(f) Secure logistics providing for large scale computer resources, effective cooperation among a large
number of researchers in Japan, and training for young scientists who are charged in research anddevelopment of DEMO.
1-2) Measures and Management Systems Required for Resolution

26

(a) Close coupling is necessary between experimental researches, and large scale simulation andintegrated modelling researches for understanding of physical mechanisms for transport barrier,density limit, beta limit, etc. It is necessary to consider promotion of international collaboration
through frameworks such as international tokamak physics activity (ITPA) and task force likestudy which concentrates resources on important issues.
(b) It is necessary to make efforts for realizing linkage among Japanese fusion plasma modelling
codes based upon the establishment of integrated code infrastructures compatible with the ITER
standard and to verify their physics models based upon comparison with existing experimental
data and large scale simulation data. Furthermore, it is necessary to enhance their international
competitiveness by developing advanced original components. For this purpose, it is necessary to
promote systematic code development based upon formation of standing research groups for eachcore component of an integrated fusion plasma simulation code such as equilibrium, transport,
stability, heating, edge plasma, etc.
(c) Fusion plasma simulations including not only the steady state condition but also the timedependent condition enable activities for the DEMO design which has reality and includes
optimization of an operation scenario. Therefore, close cooperation between an integrated fusion
plasma simulation group and the DEMO design code group is necessary.
(d) It is necessary to develop an integrated blanket code by linkages of individual fusion reactor
engineering codes for each component and develop an integrated fusion reactor engineering code
continuously including a reactor material simulation code focusing on fusion reactor materials.
(e) It is expected that researches for an integrated fusion plasma simulation code, an integrated fusion
reactor engineering code, and the DEMO design code will be integrated in the research fordevelopment of an integrated fusion reactor system simulator.
(f) It is important to effectively use large scale computer resources based upon promotion ofcollaborative research supported by a large number of researchers. It is necessary to build the
DEMO simulation centre. Furthermore, it is important to maintain a certain level of research
activities in universities which will educate future generations.
2) Analysis of Issues2-1) Sorting-out Issues○ Definition of integrated code 1: the simulation code which can treat systematically from coreplasma through edge plasma and scrape-off layer plasma to divertor plasma.
 Multi scales (time : 10ps – 1000s, spatial : 10m – 10 m).
 Various physics processes (MHD, microinstability, macroinstablity, high energy particle, atomic
and molecular process, plasma material interaction, etc.).
 Various phenomena (equilibrium, transport, current drive, heating, radiation, detachment etc.).
 From steady state to temporal evolution.
○ Definition of integrated code 2: wide range use from understanding of physical mechanisms, toreactor design, and to operational control simulator.
27

 From multi-days large scale simulation to real time simulator.
 Simulation based upon basic physics model, modelling, and empirical scaling.
 Output which enables easy comparison with experimental data.
 Interface with engineering codes such as molecular dynamics simulations in materials, thermal
analyses, electromagnetic force analyses, stress analyses, and neutronics analysis.
○ The comparison between simulation results of each component code and experimental results islimited case by case, and reproduction of the experimental results by the simulation code remains
insufficient. In particular, treatment of vertical displacement event (VDE), halo current andrunaway electrons during disruption is insufficient. For the divertor simulation, it is necessary to
clarify phenomena which can be reproduced by a fluid code and only by a particle code, and toaccelerate simulation speed by development of modelling of the divertor plasma phenomena.
○ It is necessary to promote research as an organized project, to clarify sharing of roles and allocationof responsibilities, and to define concrete milestones which are consistent with the roadmap
towards DEMO.
○ Extension to a plant simulation code by combination with engineering codes.
○ Securing resources: securing personnel resources and human training (especially personnel
resources for comparison with experimental results and code integration), computer resources.
Taking account of the argument above, the structure of the issues in Theory and Numerical
Simulation Research is arranged as shown in Fig. 6 (in particular, code development towards designand operational control for DEMO). Sectors in charge and necessary facilities, which are described inFig. 6, are summarized in Table 6.
2-2) Extraction of Core Issues
It is necessary to develop and improve the simulation model which can reproduce systematicallywhole phenomena. It is important to promote research activities systematically from two sides: one is
improvement of accuracy for each component code, and the other is systematic code management.
Based upon the structure of the issues, which is shown in Fig. 6, the prioritized core issues
addressed in Theory and Numerical Simulation Research are summarized as follows below.
What are necessary tasks before the Intermediate C&R ?
 It is necessary to develop

an integrated fusion plasma simulation code which is able to predict

fusion plasma performance by treating systematically core, edge, scrape-off layer, and divertor
plasmas based upon fusion plasma performance obtained in fusion experimental machines.
 It is necessary to develop a basic engineering code combined with thermal analysis,electromagnetic force analysis, stress analysis, neutronics analysis, etc., which enables a plant
simulation compatible with a fusion plasma simulation.

28

What are necessary tasks after the Intermediate C&R and before the assessment of Transition
Conditions ?
 It is necessary to develop a burning fusion plasma simulation code which enables prediction of
ITER plasma performance by extending an integrated fusion plasma simulation code.
 It is necessary to develop a base code for DEMO which enables prediction of the basic behaviourof an energy plant consistent with a burning fusion plasma simulation by extending basic
engineering codes.
 It is necessary to develop a simulator for real time control consistent with the above codes.
Urgent issues
 It is necessary to clarify sharing of roles for JAEA, NIFS, and universities, and to define concrete
milestones which are consistent with the roadmap towards DEMO.
 It is necessary to examine measures to secure computer resources after the BA activities.
 It is necessary to examine strategic measures to secure personnel resources.
Points of note It is necessary to conduct development involving sufficient cooperation between fusion plasma
simulation development and fusion plasma research, between plant simulation development andthe DEMO design activity, and between control simulator development and diagnostics and control
research.
 It is necessary to emphasize cost saving and process shortening by adapting a technique tosubstitute with computer simulations for engineering R&D as an important strategy in theory andnumerical simulation research.

3-6.

Reactor Plasma Research

1) Technological issues, and measures and the management systems required for resolution, whichhave been indicated in the “6th Term Report,” are summarized as follows.
1-1) Issues(a) Advancement of plasma design for a tokamak DEMO (highly integrated reactor performance,
reduction of divertor heat flux, establishment of control technique)(b) Improvement of performance of steady-state plasma by using both LHD (Large Helical Device at
NIFS) and JT-60SA (compatibility between high performance plasma and reduced heat load on
the first wall)(c) Integration of reactor plasma technology and reactor engineering (divertor test, PWI, matching
test of blanket and plasma, test of plasma control device)(d) Acceleration of training of personnel to exert leadership in the international arena.

291-2) Measures and Management Systems Required for Resolution(a) Need organized measure by integrating ITER, JT-60SA, and theoretical modeling. With regard to
improvement of divertor configuration, cooperate with overseas devices.
(b) Promote research on steady-state plasma with high performance close to the fusion condition in
the deuterium experiment in LHD, and contribute to resolution of the issues expected in ITER
and DEMO through academic systematization of toroidal plasmas.
(c) Implement many of integrated tests of reactor plasma technology and reactor engineering underhigh neutron irradiation environment in ITER. Carry out tests of innovative ideas and tests which
are difficult in ITER due to device constraints, in JT-60SA and LHD(d) Establish a framework of JT-60SA experiment so that domestic research community team canexert international initiative and leadership. Need a system of management and human affairs
enabling researchers from universities and others to attend ITER and JT-60SA experiments with
their long-period or resident stay. Secure human resources steadily from a long-range perspective.
2) Analysis of Issues2-1) Sorting-out Issues○ Demonstrate steady-state operation○ On ensuring divertor soundness, establish a divertor plasma control scenario enabling maintenanceof detachment, high radiation loss by impurity injection and suppression of edge localized mode(ELM), in addition to assessment of the heat load corresponding to fusion output and the coolingcapability from divertor configuration.
○ Mitigate influence of reactor plasma properties attributed to high beta (high heat flux, high neutron
flux, and frequency of disruption) under the DEMO environment, where there are engineering
constraints of cooling performance of in-vessel components and materials and control coils cannot
be installed inside the vacuum vessel○ With regard to avoidance and mitigation of disruption, prediction of the occurrence by real timeassessment code based upon diagnostics is a critical issue and assessment of the margin ofoperating limits is important.
○ With regard to establishment of control technique and logic, develop the database of physics
parameters to be controlled and their response characteristics and establish an operation scenario
based upon the database.
○ It is important to demonstrate the burning control technique in ITER, the integrated reactor plasma
performance required for DEMO in JT-60SA, and their extrapolation to DEMO based upon
theoretical modeling.
Taking into account the argument above, the structure of the issues in Reactor Plasma Research isarranged in Fig. 7. Sectors in charge and necessary facilities, which are described in Fig. 7, aresummarized in Table 7.

302-2) Extraction of Core Issues
It is necessary for Reactor Plasma Research to grapple with resolution of the DEMO issues byadvancing supportive and complementary researches in JT-60SA steadily as both a domestic coredevice and a satellite tokamak, by strengthening cooperation with domestic and international devices
and by optimizing the use of the achievements in ITER towards DEMO. In particular, it is important to
get the prospect for ensuring device soundness by demonstrating reduction of divertor heat load andpulsed heat load due to ELM and control techniques of disruption as well as the prospect for control
technology for steady fusion output by demonstrating high-beta steady state operation, high densitywith high confinement and particle control technique.
Based upon the structure of the issues, which is shown in Fig. 7, the prioritized core issues
addressed in Reactor Plasma Research are summarized as follows below.
What are necessary tasks before the Intermediate C&R ?
 It is necessary to advance development of physics models and improvement of performance
prediction codes in order to assess feasible integrated reactor plasma performance. In particular,
viewpoints of compatibility between the steady high performance plasma and the reduced heat loadon the first wall are important.
 It is necessary to advance development of the DEMO physics database in order to improveextrapolating capability of the reactor plasma performance to DEMO by extending the ITER
physics database based upon research progress of experiments, theory and simulation.
 It is necessary to focus the reactor plasma parameters through advancement and establishment ofconvincing reactor plasma design by considering compatibility between the target of DEMO andthe constraints of reactor engineering.
 It is necessary to reflect the approach to resolving the DEMO issues in research plans of ITER and
JT-60SA.
 It is necessary to initiate development of the database by utilizing domestic plasma experiments
and divertor testing devices in order to extend basic data of tungsten materials related toplasma-wall interaction
What are necessary tasks after the Intermediate C&R and before the assessment of Transition
Conditions ?
 It is necessary to demonstrate the high-beta steady-state operation with over no-wall beta limit
under the condition without in-vessel control coils which are unable to be installed inside thevacuum vessel in DEMO.
 It is necessary to demonstrate high density and high confinement operation by clarifying physics
mechanisms of confinement degradation appearing in the high-density regime.
 It is necessary to demonstrate high radiation loss operation and detachment operation towards
reduction of divertor heat load, and particle control technique for refueling and helium ash exhaust.
31

 It is necessary to demonstrate small or no ELM operation, which does not damage the soundness ofthe divertor, in order to reduce pulsed heat load by ELMs.
 It is necessary to demonstrate control technique for substantial mitigation at the occurrence ofdisruption because disruption is a critical issue to threaten device soundness.
 It is necessary to demonstrate burning plasma with Q=10 in ITER in order to acquire the control
technique of burning plasma.
 Based upon resolution of these issues, it is consequently necessary to show the prospects forcontrol techniques of steady fusion output and for ensuring device soundness.
Urgent issues
 Need to develop ITER and JT-60SA research plans reflecting the DEMO physics design, and toextend database towards DEMO by utilizing ITPA and domestic and abroad devices before
JT-60SA becomes operational.
 Need to establish the system from now which enables human resource development andparticipation of researchers from universities and others for their long or resident stay in order toparticipate in the experiments of ITER and JT-60SA in a framework of implementation throughout
Japan.
Points of note
 Need to clarify the content of the item “demonstration of burning control in self-ignition regime” inthe Transition Conditions.
 Need to strategically organize the exchange and mobility of human resources in order to strengthen
relationships of feedback and feed-forward between the DEMO design and experiments in ITER
and JT-60SA.
 Need to actively promote ITER remote experiments in order to extend the participating researchers
and to nurture young researchers through the operation of the ITER Remote Experimentation
Centre (REC) prepared by BA activities, to accumulate data of ITER and other tokamaks
strategically in REC to utilize optimize development and validation of theoretical simulation andthe integrated code, and plasma modeling research by making full use of the accumulated data.
 Need to urgently develop (mobilize) young researchers (under thirty) in charge of DEMO in the
future under a situation where there is no large tokamak experiment in Japan until 2019.
 It is important to show the prospect for plasma control technique based upon the technologies
available and feasible in DEMO.
 Measures for the issues originating in high-beta in tokamak in Japan are only available on JT-60SA.
Need to accelerate the activities in JT-60SA to increase heating power and to prepare diagnostics insolidarity with domestic plasma experimental devices in order to show the prospect to resolve theseissues in JT-60SA in advance of the high beta experiment in ITER.
 Need to carry out the LHD deuterium experiments with upgraded heating power and the extended
pulse length early in order to clarify the issues in long pulse property of large heat flux on divertor,
32

and then need to reflect them in the DEMO conceptual design.
 Need to upgrade to tungsten divertor in JT-60SA at an appropriate time based upon theexperimental results on tungsten divertor in ITER and other devices in order to develop control
technique of detachment consistent with the DEMO design under the tungsten divertor envisagedin DEMO.
 Need to organize the framework to optimize intrinsic advantage of each domestic plasma
experimental device such as LHD, GAMMA10 (Tsukuba University), QUEST (Kyushu
University), and others in order to compile the basic data for the DEMO design with regard toplasma wall interaction including tungsten as a common objective.
 Need to promote development of control simulator applicable in the early phase of JT-60SA
operation in cooperation with universities and others, and to examine demonstration test of thesimulator in ITER in order to establish practical and reliable control technique and control logic.

3-7.

Fuel Systems

1) Technological issues, and measures and the management systems required for resolution, whichhave been indicated in the “6th Term Report,” are summarized as follows below.
1-1) Issues(a) Establishment of handling technology for large amounts and high concentrated tritium and heatmedium containing tritium, material accountancy and securing initial loading of tritium.
Furthermore, development of large scale technologies to deal with these issues.
(b) Development of large scale technologies for handling waste liquid and the detritiation systemfrom solid waste.
(c) Programmatic resolution of safety issues including tritium handling consistent with research anddevelopment of the blanket and the divertor.
(d) It is indispensable for tritium breeding to secure lithium 6 for initial loading to blankets andcontinuous reloading depending on the operational condition. From the viewpoint of securing
logistics, the technology should be nationalized. In order to establish technology for separationand collection of lithium, technological development for scale-up through the selection process
and development of a plant is necessary.
1-2) Measures and Management Systems Required for Resolution(a) A new large-scale facility is necessary for development of the tritium technology. It is possible toset equipment for development of material accountancy technology in the test facility under the
DT environment for the blanket and the divertor. It is necessary to examine the production
process for initial loading of tritium.
(b) With regard to the technology of waste handling, the technology obtained in ITER is not
sufficient. Therefore, it is necessary to establish an implementation framework for development33

of large-scale technology and verification of operation.
(c) With regard to the technology of tritium collection and the recovery system, it is necessary todevelop the technology, including material accountancy, with high resolution through theexperiments of ITER and JT-60SA, etc.
(d) It is necessary to select the production process for securing lithium 6 and to start promptly the
research and development for scale-up. It is important to formulate a plan so that an isotope
separation process is incorporated into the strategy of securing large amounts of lithium resourcefor batteries.
2) Analysis of Issues2-1) Sorting-out Issues○ Research and development towards ITER
 Research and development of individual processes necessary for the tritium fuel cycle in afusion reactor (such as isotope separation and impurity removal).
 Compilation of data for material-tritium interactions.
 Accumulation of experiences for safe tritium handing (from operation in world-wide tritium
facilities including material accountancy and the detritiation process)○ Research and development in ITER
 Operation and demonstration of tritium fuel cycle system as an integrated system.
 Accumulation of experiences for safety tritium handing as a fusion reactor.
 Demonstration of the detritiation system (wet scrubber technology) which is adopted for the
first time in ITER.
 Demonstration of tritium collection and recovery in blanket and water handling.
○ Research and development other than ITER
 Examination of a large-scale facility (including human training) Development of equipment treating gases and water, in which tritium is contained: vacuum
pump (ex. membrane pump), turbine, etc.
 Securing initial loading of tritium: examination of the production process (collection from aheavy water nuclear reactor and/or reprocessing facilities), import from abroad on a massive
scale (exs. Canada and South Korea), start-up scenario without initial loading (consistency ofnecessity of neutral beam heating with a heating scenario).
 Examination of technology for securing lithium 6 and development of its plant.
○ With regard to the research and development towards ITER, it is important to promote researchand development effectively for the above items using domestic facilities such as the Tritium
Process Laboratory (TPL) in the JAEA Tokai site, the DEMO R&D building constructed in BA
activities in the JAEA Rokkasho site, and the hydrogen isotope research centre at the University of
Toyama. With regard to the research and development towards DEMO, in addition todemonstration and accumulation of the technology in ITER, demonstration and accumulation of thetechnology in a large scale facility and human training in this facility are important.
34

Taking account of the argument above, the structure of the issues in Fuel System is arranged inFig. 8. Sectors in charge and necessary facilities, which are described in Fig. 8, are summarized inTable 8.
2-2) Extraction of Core Issues
ITER is the first plant to establish an actual fuel system including tritium handling, and provides
the guidelines for subsequent research and development. Therefore, development of the equipment for
ITER and accumulation of the tritium handling technology in ITER should be done with highest
priority.
Based on the structure of the issues, which is shown in Fig. 8, the prioritized core issues
addressed in the Fuel System are summarized as follows below.
What are necessary tasks before the Intermediate C&R ?
 It is necessary to define the fuelling scenario in DEMO and to clarify specifications of the fuelcycle system taking into account fuel inventory.
 It is necessary to develop components of the fuel cycle system such as impurity removal andisotope separation, and to establish the component technologies.
 It is necessary to demonstrate the detritiation system and the accumulation of experience for tritium
accountancy, and to establish safe handling technology.
 It is necessary to obtain base data for tritium handling such as tritium material interactions.
What are necessary tasks after the Intermediate C&R and before the assessment of Transition
Conditions ?
 It is necessary to start the DT operation in ITER and to verify the fuelling scenario by maintaining
the burning condition for a long time.
 It is necessary to demonstrate that the components of the fuel cycle system work according to their
specifications in ITER.
 It is necessary to demonstrate that the detritiation system works according to the specifications andto accumulate operation experience with accurate tritium accountancy in ITER.
 It is necessary to verify that the equipment treating tritium works according to the specifications in
ITER.
 It is necessary to obtain prospects of the technology for securing lithium 6, which is used fortritium breeding.
 It is necessary to obtain prospects of the technology for securing the initial loading of tritium oralternative measures.
Urgent issues
35 It is necessary to decide specifications of the fuel cycle system consistent with the fuelling scenario
in DEMO in order to establish the concept of the fuel system required in DEMO.
 It is necessary to estimate fuel inventory in DEMO, which influences significantly the fuellingscenario, based upon analyses of the existing experimental data.
Points of note It is important to complete the Japanese commitment to the ITER project through the procurementof the detritiation systems and promote activities to accumulate the technologies for the fuel cycle
system required in DEMO by utilizing ITER.
 With regard to handling and securing tritium and lithium 6, not only establishment of thetechnology in Japan but also implementation of research and development under an internationalframework are required.

3-8.

Material Development and Establishment of Codes and Standards

1) Technological issues, and measures and the management systems required for resolution, whichhave been indicated in the “6th Term Report,” are summarized as follows below.
1-1) Issues(a) Towards establishment of codes and standards for a fusion reactor structural materials, a basic
safety policy in the fusion reactor and related structural design criteria must be determined withfurther understanding of materials characterization and the degradation mechanisms.
(b) Alternative and compound approaches not relying solely upon the early realization of IFMIF(International Fusion Material Irradiation Facility) should be examined and conducted in order toacquire a fusion neutron irradiation database required for the pre-conceptual design activities ofDEMO.
(c) Establishment of testing standards is required for Small Specimen Testing Technologies (SSTTs)
which are the basis for compiling the irradiation data.
(d) Active and prolonged participation of industries is essential to enable practical use of structural
materials because their development requires a long period of time.
1-2) Measures and Management Systems Required for Resolution(a) <Measure> Establish the basic policy for ensuring the safety of the fusion reactor and structuraldesign codes and standards. And also clarify design requirements for the structural materials.
<Management system> Grapple with the related BA activities in a framework for implementation
throughout Japan. Take into account feasible cooperation with the Japan Society of MechanicalEngineers (JSME) and the American Society of Mechanical Engineers (ASME).
(b) <Measure > Define the design activities based upon expected irradiation data before theengineering design activities of DEMO.

36

<Management system > Based upon the irradiation data obtained from the fission reactors,
spallation neutron sources and other facilities, the reduced-activation ferritic steel is expected to be
utilized in a range up to the critical condition that will emerge from fusion neutron-specificirradiation effects. These activities are being promoted in the BA activities as irradiation
simulation experiments and modelling studies, as well as in the broad contributions of basic
research performed in universities.
<Measure > This strategy requires large amounts of neutron irradiation data.
<Management system > In addition to further enhancement of current irradiation studies
through international cooperation, the development of domestic high-dose irradiation researchusing fission research reactors in Japan is highly expected.
< Measure > Early realization of IFMIF is particularly desirable in terms of the compilation ofreal environment irradiation data for the engineering design. It should also be noted that
demonstration of the critical condition of fusion neutron-specific degradations by the initial
operation of IFMIF is important.
<Management system > Development of IFMIF is being currently performed mainly by Japanand Europe under the EVEDA (Engineering Verification and Engineering Design Activity) in theframework of the BA. In order to initiate construction of IFMIF and the related activities, it isnecessary to clarify the role of promoting the international body and to strengthen the preparatory
activities. Although international organization has been established in the International Energy
Agency (IEA) as the existing framework, its activities outside Japan and Europe are inactive.
Enhancement of international cooperation is necessary.
<Measure > Even in the pre-conceptual design phase, if early acquisition of irradiation dataclose to the fusion environment is demanded for ensuring safety and design requirements, theavailability of an irradiation facility preceding IFMIF is an urgent issue. Development of a neutron
irradiation facility by extending the accelerator constructed in BA activities is thought to be thenearest term option.
<Management system > In order to realize this kind of facility, it is urgently required to launch
the framework for implementation throughout Japan.
(c) <Measure> In order to utilize the currently compiled neutron irradiation data and future IFMIF
irradiation data as the design data of DEMO, the establishment of standards for SSTTs is required.
Development of the guidelines for SSTTs standards must be decided quickly.
<Management system> Establishment of the organization and the management system for the
standardization of materials testing is urgently required. Activities in academic societies should beinitiated immediately so to begin the deliberation of standards. In addition, it is necessary tofurther promote international cooperation programs.
(d) <Measure> It is expected that declaration of a national policy of energy resource development in
its early stage will encourage the active participation of industry. Also, in terms of human resource
development, efforts to increase the willingness of young researchers to engage in fusion research,in particular, in the field of fusion materials development, are expected.
372) Analysis of Issues2-1) Sorting-out Issues○ Towards establishment of codes and standards, it is necessary to characterize material properties
and to understand degradation mechanisms. Establishment of basic policies of safety andcorresponding structural design criteria are required.
○ Material standards that take into account the fusion neutron irradiation effect are necessary. It isnecessary to clarify the methodology of testing standards for the utilization of irradiation dataobtained by small specimens in past experiments and in future tests in IFMIF. And consideration ofalternative and compound approaches that do not relying solely upon the early realization of the
IFMIF for clarifying of radiation effects of fusion neutrons and their implementations is demanded.
○ Development of human resources with a point of complex views and continued long-termcooperation with industries is necessary
Taking into account the argument above, the structure of the issues in Material Development andEstablishment of Related Codes and Standards (in particular, for the blanket structural material) isarranged in Fig. 9. Sectors in charge and necessary facilities, which are described in Fig.9, aresummarized in Table 9.
2-2) Extraction of Core Issues
Establishment of the material standards of reduced-activation ferritic steel, which is a baselinematerial for the blanket of DEMO fusion reactor, requires material characterization and anunderstanding of the degradation mechanisms. This process should be based upon the basic policy toensure safety in the design activity and the corresponding concepts of structural design codes andstandards. The material standards should be considered, including the fusion neutron irradiation effect,
which is represented by transmutation. Methodology to utilize the irradiation data derived from small
specimens used in past experiments, future IFMIF experiments and other experiments should beestablished as a testing standard.
With regard to the fusion neutron irradiation effect, alternative and compound approaches such as
the construction of a new fusion neutron source which is able to verify effects of the heliumtransmutation and the effective utilization of the existing fission reactors should be examined andundertaken not relying solely upon the IFMIF or the early realization of an intensive fusion neutron
source with neutron spectrum and flux equivalent for the IFMIF.
Based upon the structure of the issues, which is shown in Fig.9, the prioritized core issues
addressed in Material Development and Establishment of Related Codes and Standards, in particular
the reduced-activation ferritic steel are as follows below.

38

What are necessary tasks before the Intermediate C&R ?
① It is necessary to establish mass-production technologies for the reduced-activation ferritic steel.
② It is necessary to establish blanket structure fabrication technologies.
③ It is necessary to initiate preparatory activities for materials standardization in academic societies
and other related communities.
④ It is necessary to obtain 80 dpa irradiation data by using fission reactors.
⑤ It is necessary to establish the reliability of small specimen evaluation data.
What are necessary tasks after the Intermediate C&R and before the assessment of the Transition
Conditions ?
① It is necessary to clarify demands upon the structural materials for DEMO.
② It is necessary to present technological specifications of blanket structural materials for DEMO.
③ It is necessary to obtain data regarding joining/coating, effects of electromagnetic force,compatibility with coolants, and the irradiation effect on these properties.
④ It is necessary to develop understanding of the effect of the helium transmutation using fusion
neutron sources.
⑤ It is necessary to standardize SSTTs.
Urgent issues① Clarification of a material database which must be acquired in order to develop the structural

material standards through dialogue with related academic societies and the DEMO reactor design
team.
② Irradiation plans using fusion neutron irradiation sources or existing irradiation facilities should be

proposed in order to develop codes and standards for the structural material to be used as theprime candidate for the DEMO blanket.
③ For items which cannot be evaluated in the irradiation plan, it is necessary to clarify amethodology for compensating with simulation and modelling.
Points of note
① With regard to advanced materials, investigation of how they may be utilized through discussion
with the DEMO reactor design team and compilation of a material database should be carried out
in order to judge their applicability at the assessment of the Transition Conditions.
② Since the High Flux Isotope Reactor (HFIR) at the Oak Ridge National Laboratory, in the UnitedStates, is the only available fission neutron irradiation facility for high dose experiments. Early
re-start of domestic reactors such as JMTR and JOYO is hoped for.
③ Material development requires a long period of time. Long-term and active participation ofindustries is essential for the steady development of practical materials.

39

3-9.

Safety of DEMO and Safety Research

1) Technological issues, and measures and the management systems required for resolution, whichhave been indicated in the “6th Term Report,” are summarized as follows.
1-1) Issues(a) Assessment of safety and environmental effect of tritium based upon the understandings ofengineering safety of a fusion plant.
(b) Quantification of environmental behaviour of tritium and its biological effects, safety
management and securing of public acceptance in keeping with the fact that tritium is released tothe environment even under normal operation.
(c) Establishment of a framework according to Japan’s characteristic conditions for safety research
about abnormal plant behaviour and appropriate measures.
1-2) Measures and Management Systems Required for Resolution(a) <Measure> Clarify the accident sequence, which is important in DEMO, develop safety design
measures to prevent and/or mitigate effects of the accident and establish the safety guidelines.
Compile material data by future experiments sufficient to predict chemical energy in the blanket.
With regard to tritium inventory, mature data so as to manage tritium in the vacuum vessel, thesurface and the inside of blankets appropriately. Develop the safety requirement standard to meetthe natural feature and social circumstances in Japan and the corresponding guideline of thesafety design of DEMO.
<Managing System> Long term strategy to keep human resources is necessary while taking
account of the situation that researchers in the safety field are lacking worldwide.
(b) <Measure> Build and establish social understandings of radiation based upon steady sharing of
substantial support to the assessment research on environmental effects of radiation. Accumulate
operating experience in the tritium handling facility in the BA activities and other fusion facilities,
and build relationships of mutual trust with the local societies so as to lay the social groundwork
to accept fusion energy.
<Managing System> With regard to the issue of environmental safety, cooperation withresearchers in wide fields including fission, radio-biology environmental, etc., is indispensable.
With regard to the fact that tritium can be detected in the environment even under normal
operation, and its effects, establishment of a research framework to gain social understanding andlong-term accumulation of research achievement is important.
(c) <Managing System> It is necessary to create a favourable environment for a long-term nurturingof human resources to solve the serious organizational problem that researchers supporting thebase of the environmental safety field (e.g.: environmental behaviour of tritium) are not supportedby the fusion field. Training of young engineers and/or researchers who will collect and retrieve
the experience of tritium handling in ITER is also necessary. Since the safety research is40

inseparably related to the conceptual design activity of DEMO, it is critically important toorganize a framework of implementation throughout Japan which works as a core of the DEMO
design.
2) Analysis of Issues2-1) Sorting-out Issues○ Data related to examination of safety (material properties, chemical reaction) is not sufficient. The
reason preventing earnest development is that the material for the DEMO blanket has not been
selected.
○ It is a serious common issue that researchers in charge of examination of a plant, including safetyassessment, in particular, and researchers in charge of environmental behaviour and effects oftritium are few.
○ After the invitation activity of ITER, development of both computer simulation codes for safety
analysis and verification and validation test facilities remains stagnant.
Taking account into account the argument above, the structure of the issues in Safety of DEMO
and Safety Research is arranged in Fig. 10. Sectors in charge and necessary facilities, which ae
described in Fig. 10, are summarized in Table 10.
2-2) Extraction of Core Issues
The problem in the assessment of safety is due to the breakup of the examination team after theinvitation activity of ITER and stagnation of major activities. It is important to re-launch the activity
as a project. The examination team for safety should be organized to promote a wide range of support
from industry, government, and academia including other fields.
Based upon the structure of issues, which is shown in Fig. 10, the prioritized core issues
addressed in Safety of DEMO and Safety Research are summarized as follows below.
What are necessary tasks before the Intermediate C&R ?
 It is necessary to review plans and schedule of compilation of material data, development ofcomputer simulation codes for safety analysis and facilities required for verification and validation
tests and to package them in a project
What are necessary after the Intermediate C&R and before the assessment of the Transition
Conditions ?
 It is necessary to arrange the safety requirement standard and the corresponding guidelines of thesafety design of DEMO. The examination should be reasonably implemented taking account of
intrinsic safety features of a fusion reactor as well as existing regulations and standards/criteria.
 It is necessary to conduct preliminary examination of formulation of regulations and licensing
41

process.
 It is necessary to assess social acceptance of DEMO plant
Urgent issues
 It is necessary to enhance safety study and compilation of material data and to strengthen
justification of a pre-conceptual design.
 It is necessary to clarify firstly the specifications required for DEMO and then the corresponding
requirements to elements.
 For the above activity, a framework for pre-conceptual design including examination of safety
should be organized.
Points of note
 An organized framework of a team should be attractive and significant to participating researchers
from different fields.
 The examination team working for ITER invitation was dismissed.
 Absence of a project of safety examination leads to difficulty of support from industry.
 While experts for safety are limited, their demand is great in other fields.

3-10． Availability and Maintainability
1) Technological issues, and measures and the management systems required for resolution, whichhave been indicated in the “6th Term Report”, are summarized as follows below.
1-1) Issues(a) Understanding on whole view of availability and maintainability including economy, RAMI
(Reliability, Availability, Maintainability, Inspectability), safety, etc. Making a proposal of “acertain economy” considering prospects of a maintenance method, the approaches for
ensuring reliability (concept of quality assurance, redundancy, and safety margin), inspectability
and risks of unscheduled shutdowns.
(b) Lifetime prediction of in-vessel components and showing the direction of efforts forlifetime extension.
(c) Establishment of a comprehensive maintenance concept including a maintenance method,
reactor structure, reactor building, and hot cell. Development of radiation resistant devices
and system integration.
1-2) Measures and Management Systems Required for Resolution(a) Establish RAMI as an evaluation formula of DEMO system to obtain perspectives onavailability and economy. Build database on failure rates of equipment and devices
utilizing ITER and other international cooperation.

42

(b) It takes significant time to understand erosion of plasma facing materials which is the mostcritical factor to determine the lifetime. Grapple with this issue based upon sustaining efforts withlong-term perspective.
(c) Initiate development and tests on remote handling techniques, radiation resistant equipment
and lifetime evaluation of in-vessel components aiming for DEMO after the BA activities.
Ensure long-term availability of a high-dose rate gamma-ray irradiation facility and carry out
radiation hardness tests. Apply experiences in ITER to handling of large-scale components, hot
cells, decontamination, repair of in-vessel components, inspection, waste disposal, etc. Constructa framework in which industry can join as one of the major players for investigation anddetermination of feasibility of a maintenance concept and manufacturing.
2) Analysis of Issues2-1) Sorting-out Issues○ Construction of a comprehensive maintenance concept including a maintenance method, reactor
structure, reactor building and hot cell, and making a proposal of availability (with higher
priority).
○ Lifetime prediction for in-vessel plasma facing components, especially for divertors, isdifficult (with higher priority).
○ Development of criteria of demonstration in a DEMO and the corresponding R&D plan based
upon a scheduled maintenance scenario and the method which can achieve availability withprospects for economy.
○ Investigate risk factors for unscheduled shutdowns of a system and study inspection,
mitigation, redundancy, and measures to deal with them.
○ Promote R&D on remote handling techniques for replacement of packaged large-scale
components, transport, etc., required newly in a DEMO.
○ Promote R&D on functional materials, devices and equipment with higher radiation resistantperformances. (Development during ITER-EDA aiming at 100 MGy. The target for a DEMOis >200 MGy.)
Taking into account the argument above, the structure of the issues in Availability and
Maintainability is arranged in Fig. 11. Sectors in charge and necessary facilities, which are describedin Fig. 11, are summarized in Table 11.
2-2) Extraction of Core Issues
The maintenance method concept in a DEMO should be determined at the first step in the DEMO
design since it is related closely with the reactor structure, development and design of devices andequipment and also with burning plasma control. For review and prioritization of R&D items andtargets of maintenance technology after the BA activities, investigation of components to be
maintained, required technology and procedures should be done by promoting the detailed reactor
43design. Since the present technological assessment expects that the replacement frequency of divertors
will be highest and it will determine the periodic maintenance cycle, prediction of the lifetime ofdivertors is required to obtain prospect of economy.
With regard to R&D activities, it is necessary to construct a new large-scale R&D facility for
maintenance technology and develop remote handling technology for large-scale components. It isalso required to develop radiation resistant materials and devices by utilizing existing irradiation
facilities.
Based upon the structure of issues, which is shown in Fig. 11, the prioritized core issues
addressed in Availability and Maintainability are summarized as follows
What are necessary tasks before the Intermediate C&R
 With regard to the selection of the reactor structure and maintenance method taking into
account consistency with plasma control and component designs, and safety, it is necessary
to make a corresponding proposal quickly by the DEMO design team since it affects various
R&D elements.
 Subsequently investigate and select specific maintenance technology and working proceduresby involving results of detailed investigation and design for maintenance in ITER, and also
technology in fission reactors. Based upon this involvement, R&D items newly required for
DEMO can be clarified. At the intermediate C&R, it is necessary to show results offeasibility review taking technology base into account in addition to proposals of amaintenance method, technology, and working procedures.
What are necessary tasks after the Intermediate C&R and before the assessment of the Transition
Conditions ?
 With regard to R&D of remote maintenance technology newly required for a DEMO, it isnecessary to construct a new development facility for large-scale maintenance and promote
the development by involving achievements of maintenance technology obtained in ITER andremote robot technologies in industry.
 With regard to radiation resistant functional materials and devices for sophisticated andefficient remote maintenance, it is necessary to carry out development aiming for integrated
dose of 200 MGy based upon the results up to 100 MGy obtained during ITER-EDA.
 At the assessment of the Transition Conditions presumed around 2027, it will be necessary toshow the prospect of availability based upon a periodic replacement cycle predicted from thelifetime of plasma facing components, and also on detailed investigation and optimization ofmaintenance processes involving the latest R&D results. This must include examination of causes
for unscheduled shutdown based upon a database of failure rates of equipment and devices
44

accumulated in ITER, JT-60SA, etc., and their inspection and measures.
 It is necessary to define standards for disposal, reuse, and clearance of fusion reactor
materials to show perspective of the back end including a disposal building, storage site, burial
method, etc., of radioactive waste.
Urgent issues
 Strengthening of a framework for implementation of the DEMO design is necessary to makea proposal of a maintenance concept early.
 Strengthening of development of the DEMO divertor system and studies on lifetime
prediction from both viewpoints of component development and plasma control is necessary.
Points of note It is expected that the standard for disposal and reuse of radioactive waste will be establishedautonomously by JAEA, industry, universities, etc., based upon the procedure to establish thestandard of a fission reactor before the assessment of the Transition Conditions and the final
authorization of the standard by Nuclear Regulation Authority etc. will be done after theassessment of the Transition Conditions.

3-11.

Diagnostics and Control Systems

1) Some issues regarding diagnostics and the control system have been pointed out in the “6th Term
Report”, though a specific chapter was not allocated. The issue of the development of diagnostics
and the control system is recognized as one to be discussed specifically, and technological issues,measures and the management systems were analyzed because this issue is essential for thetechnological development of diagnostics and actuators, and for the development of the concept of
integrated operating scenario of DEMO. Technological issues, and measures and the managing
systems required for resolution, which have been documented in the “6th Term Report” aresummarized as follows below.
1-1) Issues(a) Development of the integrated and consistent plasma scenario including heat load control, helium
exhaust capability, and core and edge plasmas (Sec. 3.2.3 Divertor in the “6th Term Report”).
(b) Development of an operating scenario for edge plasma consistent with erosion, embrittlement andmaintenance of divertor components (Sec. 3.2.3 Divertor in the “6th Term Report”).
(c) Development of the integrated reactor system simulator for the design of diagnostics and thecontrol system for DEMO (Sec. 3.2.5 Theory and Numerical Simulation Research in the “6thTerm Report”).
(d) Establishment of practical and reliable control techniques and control logic (Sec. 3.2.6 Reactor
Plasma Research in the “6th Term Report”).

451-2) Measures and Management Systems Required for Resolution(a) Large-scale simulation experiment by utilizing magnetic confined devices is indispensable.
Ensure extrapolating capability of edge plasma in DEMO based upon the experimental researchon LHD, JT-60SA, and ITER, and modeling of laboratory plasmas (Sec. 3.2.3 Divertor in the “6thTerm Report”).
(b) Develop integrated codes covering from core plasma to divertor components (Sec. 3.2.3 Divertor
in the “6th Term Report”).
(c) It is expected that reactor plasma integrated codes, reactor engineering integrated codes, andreactor design codes will be assembled into the reactor system integrated simulator (Sec. 3.2.5
Theory and Numerical Simulation Research in the “6th Term Report”).
(d) Organize a systematic activity by combining experiments on ITER and JT-60SA, and theoreticalmodeling.
2) Analysis of Issues2-1) Sorting-out Issues○ Need to define operational standard point allowable for operating ranges derived from operating
margin against the limit and allowable fluctuation to connect to transmission grid. This enables
development of the operational control logic and simulator and focusing controlled variables andactuators.
○ Validation of the plasma modeling is necessary for development of an operational control simulator.
The accumulation of plasma response property data is important by utilizing ITER, JT-60SA, and
LHD, and enhancement of collaboration with ITPA is also important. Examination of the response
property of variables to the actuator should be reflected to the technological specification ofdiagnostics.
○ Lifetime and installation position of diagnostics are restricted by high irradiation field in DEMO. In
particular, influence of degradation in the precision of magnetic field measurements due to eddy
currents in structures on the control of plasma position and shaping is the issue of concern.
Therefore, approaches to resolve the issue, for example, the magnetics are placed far from plasma
or close to structural material in JT-60SA.
○ Development of diagnostics equipment which is indispensable for operational control of DEMO
and can be used under the DEMO environment (high irradiation field). Therefore, development ofadvanced diagnostics towards DEMO in JT-60SA and LHD together with accumulation ofoperating experience in ITER and summarizing of issues is necessary. Moreover, it is important toimprove reliability at high irradiation field by heavy irradiation testing of components constituting
diagnostics and actuators.
Taking into account the argument above, the structure of the issues in Diagnostics and Control
System is arranged in Fig. 12. Sectors in charge and necessary facilities, which are described in Fig. 12,46

are summarized in Table 12.
2-2) Extraction of Core Issue
It is important to focus clusters of essential and applicable diagnostics based upon performanceand operating results of diagnostics developed and prepared in ITER because of various constraints
due to high irradiation field in DEMO. In particular, it is necessary to show the prospect of the DEMO
relevant diagnostics through the development of essential diagnostics for burning control andradiation-proofed components, and improvement of accuracy of equilibrium control by magnetic
measurements as well as to develop the real time operation control simulator..
Based upon the structure of the issues, which is shown in Fig. 12, the prioritized core issues
addressed in Diagnostics and Control System are summarized as follows below.
What are necessary tasks before the Intermediate C&R ?
 It is necessary to focus diagnostics to be applicable to DEMO and definitely needed for operation
control.
 It is necessary to accumulate data of plasma response property for the use of model validation sincehighly precise modeling including temporal evolution of plasma is necessary for development ofoperational control simulator.
 It is necessary to define the operation standard point and surrounding allowable operating regime byclarifying the operating margin against the limits and operational control range of detached plasma.

 Based upon measures in the above mentioned issues, it is necessary to define the target
performance of diagnostics and to reflect it in research plans of ITER and JT-60SA.
What are necessary tasks after the Intermediate C&R and before the assessment of Transition
Conditions ?
 It is necessary to develop diagnostics and their analysis codes in ITER, JT-60SA and LHD in orderto achieve their performances required for control
 It is necessary to develop radiation-proofed components in parallel with evaluation of the lifetimeof diagnostics in the irradiation test facility.
 It is necessary to show the prospects for accuracy of equilibrium control under the DEMO relevant
electro-magnetic condition by using the data measured with magnetics which are placed far fromplasma or close to structural material where influence of eddy current should be large in JT-60SA.
 It is necessary to develop the real time operational control simulator in order to build control logic
under the DEMO condition where available diagnostics are restricted and to demonstrate its
function in JT-60SA and ITER.
Urgent issues
 Organize and strengthen the examination activity for diagnostics and control systems consisting of47

experts from core plasma, theory and simulation, diagnostics, and actuators
Points of note Strong cooperation with Reactor Plasma Research and Theory and Numerical Simulation Researchfor development of the real time operational control simulator is essential.

3-12.

Newly Required Facilities and Platforms

As shown in the previous sections which analyse technological issues of 11 elements of DEMO,
some issues can be dealt with by presently available programs or their expansion and improvement.
On the other hand, activities to resolve some issues have not been initiated yet because corresponding
frameworks/platforms do not yet exist. Newly required facilities etc. are summarised in the following.
 Test facility of large-scale superconducting coils which fulfils the specification of DEMO (Testfacility of superconducting conductor and coils with around 16 T)
 Facility related to blanket (development of ITER-TBM, post irradiation examination,
development of waste disposal technology)
 Test facility of real-scale performance of NBI (including expansion of ITER NBTF)
 Supercomputer resource Handling facility for large quantities of tritium Lithium plant (collection and purification facility)
 Intensive fusion neutron source, fusion neutron source (including expansion of IFMIF/EVEDA)
 Facility for development of large-scale component maintenanceWith regard to newly required facilities, full use should be made of available infrastructure
beginning with facilities prepared in the presently ongoing programs such as the BA activities, andalso expanded. In particular, it is necessary to develop the BA site in Rokkasho as the central core basefor development of DEMO and to organize a framework for implementation throughout Japan byclarifying the roles together with the BA site in Naka, NIFS, and Universities and reinforcing
cooperation.

4. Points of Reactor Design Activity
What is required in the DEMO design activity is to show the concept which is feasible by reliable
extension of the present technology bases and fulfils social requests. Here DEMO is on only one-stepfrom ITER to commercialization, which is prospected in the middle of the 21st century.
Development of DEMO is arranged so as to bring together all related technology from a positionof integration. Therefore, the DEMO design activity in wide definition is requested to manage the48

overall development plan by definition of the target of each technology and assessment oftechnological maturity, and to pronounce newly required technological developments.
In order to show the economic feasibility of fusion energy by DEMO, DEMO is requested topursue superior performance for high-efficiency energy production by improvement of components inaddition to accumulation of operating experience (guarantee of availability reachable tocommercialization, reduction of unplanned downtime ratio, etc.) in order to prove reliability as anenergy production system. Therefore, design should be flexible so as to enable refinement ofcomponents and test for improved performance in service. Furthermore, the estimate of the cost of acommercial reactor should be incorporated into the DEMO design, and it should include not only thecost of construction and operation but also the back-end cost of decommissioning and disposal ofwaste.
The DEMO design should be conducted from a position of integration covering all features fromtechnological feasibility to social acceptance. Therefore, it is necessary to collect the wisdom ofknowledgeable people in each field in order to cope with a wide range of problems as well as to gather
together related experts specific to DEMO technology. The system to promote personal exchange isrequired in order to set up the activity organization endowed with compound talents.
The DEMO design should secure design rationality involving material, productivity, workability,
assembly precision, maintainability, inspectionability, and refinement to prospect industrialization in
the future. Therefore, close collaborative work with industries in significant scale is necessary in theearly phase of the DEMO design. Furthermore, continuous and phased commitment of industries inlong-term prospect is required and it is quite important to take measures to facilitate it.
With regard to the level of completion by the Intermediate C&R, it is required that the overalltarget of DEMO will be decided and that technological examination to guarantee overall consistencyof the system and the prospect of real fabrication will be completed.
 Decision of overall target of DEMO Basic design of DEMO concept Addressing of development request to reactor plasma and engineering (operating scenario,
structural material, divertor material, configuration of blanket, maintenance system, etc.)
To implement the above mentioned actions, structural mechanism to grapple strategically should
be arranged in the organized framework for implementation throughout Japan promptly. Thismechanism is requested not only to reinforce the present DEMO design activity but also to make thefunction of the so-called PDCA cycle, in particular, Check and Action, work effectively in planning,
management, and coordination of the R&D plan required for engineering development for DEMO,
49

and to organize activity including coordination with other fields and academic societies to resolve
issues.

5. International Cooperation and Collaboration
Summary of activities abroad about DEMO has been described in the “Interim Report”. It has tobe noted that budgetary and human resources, and R&D and production bases in Japan are insufficient
to conduct all the R&D for DEMO alone. Therefore, it is indispensable to plan strategic international
cooperation by considering resources, technological maturity level in Japan, and complementarity toother countries/party.
The most important point is application of achievement and accomplishment in the ITER project.
By making full use of this opportunity, it is important to promote accumulation and acquirement of
useful data to resolve technological issues of DEMO by working closely with other committing
countries/party. Approach to lead the initiative not only in the construction/commissioning phase but
also in the experiment phase in ITER is primarily important for this point. Achievement andaccomplishment in the ITER project, including management aspects, will lead to international
cooperation in the development of DEMO.
International cooperation programs are pronounced in technological investigation to assess a
DEMO design and to endorse feasibility of real component fabrication. It is necessary to select what is
appropriate to be conducted under the international framework first. Based upon analysis ofcomplementarity to domestic activities, the procedure, the time line, the implementing body, andcooperation with domestic activities should be well defined in international cooperation programs.
Specifically, the following remarks are particularly important among the statements about
international cooperation described in Chap. 3.
 The effective extension from the presently ongoing projects should be promoted for facilities offusion neutron source and intensive fusion neutron source for material development, and alarge-real-scale test facility for development of heating and current-drive system.
 Since the fission neutron irradiation facility is not available in Japan now and its test has to dependon the HFIR in the United States, restart of research reactors of Joyo and JMTR is expected, andthe bilateral cooperation with the United States should be maintained.
 Since a large-scale tokamak experiment will not be available in Japan until the start of operation of
JT-60SA in 2019, cooperation with tokamak experiments abroad and simulation, specificallyregarding the detachment operating scenario and the tungsten issue, which are related to50

development of the divertor, is indispensable. In order to facilitate it, special care should be paid toproactive commitment to ITPA and related implementing agreements of the International Energy
Agency, etc.
 Since a variety of concepts of TBM in ITER depending on contributing countries and party will betested, good cooperative relation should be established so that achievement by other countries/party
will be reflected in the DEMO design appropriately.

6. Summary - Development of Grand Strategy towards Future Establishment ofTechnological Bases for DEMO In accordance with the request of the Working Group on Fusion Research, the joint-core team has
worked on strategy for establishment of technology bases required for development of DEMO bytaking into account the progress of the ITER project, the BA activities, and academic researches suchas the Large Helical Device (LHD). In particular, the concept of DEMO premised for investigation
and activities to ensure the feasibility of this DEMO concept have been examined.
The purpose of DEMO is to indicate the prospect to achieve economic and social rationality offusion energy competitive with other energy resources. In order to prepare for commercialization,
DEMO should be aimed at steady and stable power generation beyond several hundred thousand
kilowatts, availability which must be extended to commercialization, and overall tritium breeding tofulfil self-sufficiency of fuels. And the roadmap towards DEMO with defined milestones should be
elaborated. In DEMO itself, the operational development phase of DEMO before reaching the targets
should be planned by classifying the commissioning phase, the power-generation-demonstration phase,and the demonstration of economic feasibility phase, and defining a milestone at each phase. And
targets such as demonstration of power generation by the system equivalent to a commercial reactor,
demonstration of high energy gain factor, long-pulse and long-term operation which can beextrapolated to a commercial reactor, and development and demonstration of advanced technology to
improve economic performance should be achieved in each phase.
In accordance with the “6th Term Report”, required technological activities of 11 elements of
DEMO have been sorted out in looking forward to the roadmap from the summary of issues in the“Interim Report”.
Then, each element has been analysed in order to clarify the procedure to demonstrate thetechnological feasibility of DEMO, which is the most fundamental mission, and to develop theroadmap with the timeline and implementing bodies. Here Intermediate C&R and the assessment ofTransition Conditions, which have been defined in the “Future Fusion R&D”, are presumed around2020 and 2027, respectively. Then, in view of the timeline, the structure (tree) of technological issues
51

in each element and approach to resolve these issues are shown. While some issues can be dealt withby the presently ongoing projects and existing implementing bodies/platforms or their
expansion/reinforcement, there still remain issues which are not yet dealt with because of the lack ofcorresponding projects and implementing bodies. These two classes are distinguished in Tables 2 - 12.
Based upon the analysis of the structure of technological issues, aligned R&D programs with defined
milestones, and plans of research bodies grappling issues and required facilities, the following are
identified.
1) What is required before the Intermediate C&R
2) What is required after the Intermediate C&R and before the assessment of the Transition
Conditions (driving the content mentioned as “Promotion to start the enterprise of engineering
R&D in accordance of the assessment at the Intermediate C&R” in Section 2.5).
3) Urgent issues4) Points of note
While the investigation in this present report endorses the view that the draft targets at theIntermediate C&R described in the “Future Fusion R&D” are appropriate, the progress of the ITER
project will have a great impact on time and criteria at the Transition Conditions. In particular, based
upon common recognition about when and how much the results of energy gain, long-pulse operation,and demonstration of blanket function, etc. will be obtained in the ITER project, time and criteria at
the Transition Conditions should be discussed in a council such as Working Group on Fusion Researchat an appropriate time.
The problem recognition common in all 11 elements is the dilemma between design of DEMO
and R&D for each technological issue. In short, it is nothing but changing the situation from an
unfavourable situation in which a target of technological R&D cannot be defined because the design is
not fixed and that the design cannot be fixed because the prospect of technological R&D is unclear, toa favourable situation in which the progress of both sides accelerates each other synergistically.
Development of DEMO is arranged so as to bring together all related technology from a position of
integration. Therefore, the DEMO design activity in wide definition is requested to manage the overall
development plan by the definition of the target of each technology and assessment of technologicalmaturity, to promote secure progress of the main stream, and to pronounce innovative technologicaldevelopments for breakthrough. In the DEMO design activity, a structural mechanism to grapple
strategically should be arranged in the organized a framework for implementation throughout Japan
promptly in order not only to reinforce the present DEMO design activity but also to make thefunction of the so-called PDCA cycle, in particular, Check and Action, work effectively in planning,
management, and coordination of the R&D plan required for engineering development for DEMO,and to organize activity including coordination with other fields and academic societies to resolve
issues. This report here requests the Working Group on Fusion Research to discuss this mechanism to52

plot a comprehensive strategy of establishment of technological base for DEMO.
At the end, although the joint-core team is responsible only for scientific and technologicalanalysis, it would like to express expectations to governmental administration. Since theappropriateness of DEMO is judged by society, the joint-core team expects leadership bygovernmental administration to define the responsibility of the implementing body as it should be, tocreate a mechanism to involve stakeholders and the public in technological assessment to prevent
self-centered planning, and to define locational conditions and environmental assessments as theyshould be based upon the intrinsic safety features of fusion.
This report is founded on intensive discussions and upon opinions received from the Japanesefusion community at a variety of opportunities. This report was intended to have been based upon aconsensus in the fusion community in Japan, and a shared understanding is emerging in the fusion
community. We will continue to strive to collect opinions and work toward a broad consensus. The
joint-core team is deeply grateful to all contributors for their important communications.

53

References[1]

http://www.aec.go.jp/jicst/NC/senmon/kakuyugo2/siryo/kettei/kettei920609.htm in Japanese[2]

http://www.aec.go.jp/jicst/NC/senmon/kakuyugo2/siryo/kettei/houkoku051026_e/index.htm[3]

http://www.aec.go.jp/jicst/NC/iinkai/teirei/siryo2005/kettei/kettei051101.pdf in Japanese[4]

http://www.efda.org/wpcms/wp-content/uploads/2013/02/JG12.356-web.pdf[5]

http://www-naweb.iaea.org/napc/physics/meetings/TM45256.html[6]

http://www.mext.go.jp/b_menu/shingi/gijyutu/gijyutu2/017/gaiyou/__icsFiles/afieldfile/
2009/11/16/1286888_1.pdf in Japanese[7]

http://www.mext.go.jp/b_menu/shingi/gijyutu/gijyutu2/017/gaiyou/__icsFiles/afieldfile/
2009/11/16/1286893_1.pdf in Japanese[8]

http://www.aec.go.jp/jicst/NC/senmon/kakuyugo2/houkoku/090122-houkokusyo.pdf[9]

http://www.mext.go.jp/b_menu/shingi/gijyutu/gijyutu2/056/shiryo/attach/1338925.htm inJapanese[10] http://www.mext.go.jp/b_menu/shingi/gijyutu/gijyutu2/056/shiryo/attach/1338911.htm inJapanese[11] http://www.mext.go.jp/b_menu/shingi/gijyutu/gijyutu2/056/shiryo/1345741.htm in Japanese[12] http://www.mext.go.jp/b_menu/shingi/gijyutu/gijyutu2/017/shiryo/07110607/002.htm inJapanese[13] http://www.naka.jaea.go.jp/fusion-energy-forum/files/member/iter_ba/3_roadmap.pdf inJapanese[14] http://www.naka.jaea.go.jp/fusion-energy-forum/files/member/iter_ba/4_jinzai. pdf in Japanese[15] http://www.enecho.meti.go.jp/en/category/others/basic_plan/pdf/4th_strategic_energy_plan.pdf

54Member of Joint-Core Team
Memebers
Ryuta KASADA(Kyoto University)

Akira OZAKI(Japan Atomic Industrial Forum)

Ryuichi SAKAMOTO(National Institute for Fusion Science)

Yoshiteru SAKAMOTO (Japan Atomic Energy Agency)
Hidenobu TAKENAGA (Japan Atomic Energy Agency)
Teruya TANAKA(National Institute for Fusion Science)

Hisashi TANIGAWA(Japan Atomic Energy Agency)

Hiroshi YAMADA(National Institute for Fusion Science) : Leader

Experts
Kunihiko OKANO(Keio University)

Kenji TOBITA(Japan Atomic Energy Agency)

Secretariat
Osamu KANEKO(National Institute for Fusion Science)

Kenkichi USHIGUSA(Japan Atomic Energy Agency)

Observers
Akio KOMORI(National Institute for Fusion Science)

Masahiro MORI

(Japan Atomic Energy Agency)

Katsusuke SHIMIZU(Japan Atomic Industrial Forum)

Yasumi MARUSUE(Japan Atomic Industrial Forum)55

Commercialization
Demonstra7on+of+long:term+opera7on+employing+components+based+on+equivalent+physics+and+technology+to+commercial+reactor+
Demonstration of
economic feasibility
phase

Acquirement+of+commercial+viability+
technology+

Clariﬁca7on+of+possible+ra7onaliza7on+for+
economical+eﬃciency+improvements+

Development+test+of+
advanced+blanket+
employing+DEMO+
reactor+TBM++

Conﬁrma7on+test+for+predic7on+of+economical+
eﬃciency+in+commercial+reactor+
Demonstration of
preliminary
economic feasibility
phase

Demonstra7on+of
maintainability+and+
replacement+
scheme+of+in:vessel+
components+
Demonstra7on+of+
tri7um+breeding++
func7on+and+power:
genera7on+

Conﬁrma7on+of+prospect+for+economical+eﬃciency+
improvement+
Demonstra7on+of+long:pulse+burning+opera7on+with+extrapola7on+ability+toward++commercial+reactor
Demonstra7on+of+opera7onal+ﬂexibility+(Par7al+load+and+stand:by+opera7on)
Demonstra7on+of+maintainability+and+waste+disposal+
Conﬁrma7on+of+opera7onal+ﬂexibility+(Shutdown,+Restart+and+so+on)+
Demonstra7on+of+high+energy+gain+factor+

Commissioning++

Development+test+of+in:
vessel+components+for+commercial+reactor+
!
Improvement+of+blanket+employing+
DEMO+reactor+TBM++
Improvement+of+
divertor+performance++
and+so+on+

Material+development+
test+for+commercial+
reactor+Conceptual+design+for+commercial+reactor+

Demonstra7on+of+stable+long:pulse+burning++
opera7on+

Demonstra7on+of+power+genera7on+using+commercial+reactor+equivalent+system+
Commissioning
phaseEngineering+design+for+commercial+reactor++

Improvements+and+installa7on+of+in:vessel+
components+reﬂec7ng+knowledge+from+power:
genera7on+demonstra7on+phaseConﬁrma7on+of+
operability+and+
safety+Power generation
demonstration
phase

Soundness+test+of+in:
vessel+components+using+commercial+
reactor+materials+

Advancement+of+materials+and++in:vessel+components+development+
toward+commercial+reactor

Conﬁrma7on+of+stable+steady:state+opera7on+
scenario+

Advancement+of+commercial+
reactor+design

Material+data+
from+IFMIF+

Conﬁrma7on+of+stable+long:pulse+burning+opera7on+
Op7miza7on+of+opera7onal+point+
DEMO reactor
construction
phase

TargetAdvance+of+demonstra7on+test++in+DEMO+reactor
Fig. 1.

Advance+of+material+
irradia7on+test++
by+IFMIF+

Operational phase of DEMO reactor and its target
56

Superconduc7ng+Coils
Having good prospects of providing superconducting coil system required for DEMOJAEA DEMO design team
Cost estimation of superconducting coil system
Will cost estimation be included in Transition Condition 	 How much improvement will be expected by lessons learned from ITER and JT-60SA?

Assessment of the Transition
Condition	 (2027)

JAEA(DEMO design team)Lessons+learned+
from+opera7on+of+
ITER+and+JT:60SA

Final selection of materials to be used
Should be made based on both outcomes ofconceptual design and of material development

JAEA(DEMO design team)
JAEA, NIFS, ISTEC,
universities, industry,collaboration with otherfields

JAEA, NIFS, NIMS, industry,collaboration with other fields

Utilization of ReBCO

Increase production length of
Nb3Al strand

Difficult to develop for fusion
application only?

Difficult to develop for fusion
application only?

JAEA, NIFS, industry
Improve Jc of Nb3Sn strand
Satisfied with actual
performance of ITER strand
or further development
needed?

JAEA, NIFS, industry

JAEA, NIFS, industry

High strength structural
material development
Satisfied with actual
performance of ITER material
or further development
needed?

Insulation material
development
Satisfied with actual
performance of ITER material
or further development
needed?

How much was the actual margin in ITER design? What was the variation of material property in ITER construction?
Allowable stress:
800MPa?

Target Jc >800 1000A/mm2@13~16T?

Neutron fluence: ? n/m2
Absorbed dose: ? Gy

JAEA, NIFS, universities,
industry
Conductor performance
improvement
Reduce degradation of
performance under thermal
stress at fabrication andelectromagnetic stress at
operation

Superconducting coil system
conceptual design
Feedback from basic R&D
and lessons learned from
ITER/JT-60SA is
indispensable

DEMO+conceptual+designIntermediate C&R(2020)

16T class superconductor
test facility will be needed
Target: 100kA?@13~16T?

JAEA, NIFS, universities, industry
Decision on superconducting coilsystem R&D strategy
Issues reviewed based on
pre-conceptual design
Prospect of improvement onmaterial property taken into
consideration

Design+requirement+for+
superconduc7ng+coil+system
Magnetic field at plasma center

JAEA(DEMO design team)Superconducting coil systempre-conceptual design
Superconducting coil systemshould be harmonized withoverall DEMO design

ReBCO coil
50 kA @20 K, 6T
70 kA @4 K, 1 T

Nb3Sn strand
Jc>720A/mm2@12T
Quantity: >550t

Nb3Al strand
Jc>660A/mm2@15T

Allowable stressof structural
material:
667MPaInsulation material
n fluence: 1x1022 n/m2
Absorbed dose: 1x107 Gy

Production of C.C.
conductor for ITER
~80km TF
~45km CS

Experience in large
scale coil design
ITER 60SA

DesignMaterial
Fig. 2.

Error field limit

Tolerance in manufacturing

Condition of nuclear heating

Magnet construction(Is disc type the best?)

Limit in cooling path length

Large scale coil manufacturing
Tolerance: ±0.02%

Manufacturing!

Structure of issues in “Superconducting Coils”
57

Position & dimension of coils

Space for support structureetc.

Large scale Cryogenic
system design

System!

DEMO++
pre:conceptual+design+Lessons+learned+
from+construc7on+
of+ITER+and+JT:60SA+
Progress since2005 “Future
Fusion R&D”

Blanket

JAEA+! Validated+reference+data+base++! Data+base+suppor7ng+design+
standards

Reactor+Design+

JAEA+

Universi7es,+NIFS,+JAEA+

Design+of+blanket+system

Integrated+demonstra7on+of+structural+soundness,+thermal+hydraulics,+tri7um+
breeding+and+recovery+under+reactor+
condi7ons+with+small+mock:up++

Design+supported+by+experiments,+
analysis+and+standards/criteria

Improvement+of+design+and+technologies+can+be+expected+based+on++
integrated+func7on+and+performance+
examina7ons+with+mock:up+

Data+base+supported+by+
experiments+and+analysis

Standards/Criteria+

Expansion+of+fundamental+and+standard+
data+
ITER-TBM experiment+

Assessment of the Transition
Condition	 (2027)

Valida7on+of+design+and+
manufacturing+technologies+to+develop+blanket+system

Reactor+Plasma++
Research+
Control+of++
plasma+burningIntermediate C&R	 (2020)

JAEA+

JAEA+

Arranged+data+base+for+use+
in+the+design+ac7vi7es+
proper7es+of+packed+
pebble+bed+etc.

Conceptual+design+of+blanket+
systemMaterial+data+set+is+not+fully+
arranged+

Reﬂec7on+of+R&D+
achievements+

Reactor+Design+

JAEA+

Material+selec7on

Pre:conceptual+design+of+
DEMO+blanket+and+tri7um+
system

Facility to obtain material
data
Compa7bility,+vapor+pressure,+water/vaporchemical+
reac7on+rate+etc.

JAEA
Arrangement+of+basic/
reference+data+
Reference+materials+are+not+yet+selected+

ITER-TBM experiment+
Proven+manufacturing+
technology+for+blanket+system+
Blanket+system+leading+to+
DEMO+
Heat load test facility, Erosioncorrosion test loop, Safety
experiment facilities,
Tests in JT-60SA port etc.

Reactor++Design+

JAEA+
Demonstra7on+of+integrated+
func7ons+of+blanket+system+
in+fusion+environment+
Target+and+schedule+are+not+clearly+deﬁned+for+the+
demonstra7on! Basic+data+to+assess+results+of+TBM+
experiments+is+incomplete.+! Complementary+of+
limita7on+in+ITER+
environment+(pulse+
opera7on+etc.)+

Basic+data+to+assess+results+of+TBM+
experiments+is+incomplete+

Design+and+schedule+of+
irradia7on+and+tri7um+
experiments+
Targets+of+development+and+
experiment+are+not+clearly+
quan7ﬁed+

Target+of+TBM+experiments+is+
not+clearly+quan7ﬁed+Design+and+manufacturing+technologies+for+ITER+shield+blanket+
Manufacturing+of+real:scaled+mockup+of+TBM+made+of+F82H
Proper7es+of+packed+pebble+bed+

Fig. 3.

Basic+technologies+for++tri7um+(recovery,+handling+and+permea7on+etc.)

Structure of issues in “Blanket”
58

Selec7on+of+advanced+blanket+and+
heat+exchange+concepts+to+be+
priori7zed+for+DEMO:TBM+++
Universi7es,+NIFS,+JAEA+
Promo7on+of+technological+
inves7ga7on+on+power+genera7on+
systems+and+R&D+on+heat+exchange+
R&D+and+design+inves7ga7on+on+heat+exchange+and+power+genera7on+
concepts+for+advanced+blanket+
systems+are+insuﬃcient+
Inves7ga7on+on+DEMO:TBM+design,+
oﬀering+of+preliminary+design+and+
their+comparison

Experiments+on+blanket+opera7ons+
u7lizing+Integrated+circula7on+loop+
system+simula7ng+reactor+condi7ons++

Safety++Research+
JAEA+

Test+plans+for+TBM+system+and+
addi7onal+test+facili7es

Selec7on+of+materials+for+DEMO:TBM+is+required+

Proposal+of+preliminary+design,+
comparison+and+priori7za7on+are+required+between+various+advanced+
blanket+concepts+with+diﬀerent+
advantages+

Conﬁrma7on+of+soundness+to+heat+and+pressure+loads,+and+of+response+
to+EM+loads

JAEA+

Progress since Irradia7on+data+of+F82H
2005 “Future
Advanced+materials
Fusion R&D” Li2TiO3,+Be12Ti

! Understandings+of+tri7um+
behavior+! Establishment+of+tri7um+
technology

Prospect+of+tri7um+self:suﬃciency+
in+DEMO+plant+

Basis+requirements+and+corresponding+conceptual+design+of+blanket+is+not+deﬁned+Basis+material+data+is+not+arranged+to+select+reference+material+

Tritium permeation test
facility, Tritium experimentwith neutron source etc.

Simultaneous+examina7on+of+plural+
func7ons,+technologies+and+
phenomena+in+advanced+blanket+
systems+and+acquisi7on+of+
fundamental+design+data+are+required+Fabrica7on+of+small+test+devices+and+
separate+examina7on+on++blanket+
func7ons+and++proper7es+
Separate+inves7ga7on+on+technologies+and+designs+is+required+for+each+of+blanket+
fabrica7on+technology,+dissimilar+material+
welding,+coolant+ﬂow+through+complicated+channels,+transfer+and+recovery+of+hydrogen+and+heat+etc.+

R&D+on+elemental+technologies+for+advanced+
blanket+systems+(Coolant+proper7es,+hydrogen+transfer+and+recovery,+material+compa7bility,+
MHD+pressure+drop,+coa7ng+technology+etc.)

Divertor
Establishment of technology bases for divertor of DEMO
Assessment of
the Transition Condition(2027)

Proposition of possible scenario fordivertor heat-flux reduction operation

JT-60SA, ITER

Decision of materials and coolingmethod for divertor components

Proposition of possible scenario
for adequate particle exhaust

Availability and
Maintainability

Mainframe computer(University, NIFS,
JAEA)

Demonstration ofplasma operation
scenario

Development oftheoretical simulation
for burning plasmaLack of demonstrationof plasma operation
with divertor heat load
reduction

Lack of predictability
for burning plasma
operation

Establishment ofconsistent particle
exhaust scenario withheat removal

Not yet undertaken

Development ofinnovative coolingsystemUncertainty of
conventional heatremoval system
toward DEMO reactor

Understanding of
impurity effects on
fusion output

Uncertain consistency
between detachment
and particle exhaust

Linear devices, Heatload test-stand,JT-60SA, LHD(University, NIFS,
JAEA)

ITER

Not yet undertaken

Clarification of heatremoval property of
low activation material

Demonstration of heatremoval property of W
& Cu divertor under
actual condition

Clarification of neutron
irradiation effects ondivertor materials

Uncertainty of heatremoval property of
low activation material
as a divertor material

Uncertainty of
conventional heatremoval system
toward DEMO reactor

Lack of knowledge
about material
property under DEMO
reactor conditions

JT-60SA, ITER

Uncertainty of divertor
detachment withreasonable plasma
confinement

Intermediate C&R(2020)

Not yet undertaken

Clarify effects of heat-flux reduction
operation on plasma confinement

Clarify heat removal property ofdivertor components

Decision of major candidate for divertor
materials and material selection forneutron irradiation testITER

Not yet undertaken

Understanding ofhydrogen behavior
under actual condition

Development offeasible vacuum pumpunder DEMO reactor
conditions

Lack of understanding
about particle balance
under DEMO reactor
conditions

Immature pumping
technology toward
DEMO reactor

Clarify requirements for vacuum pump

Reactor Plasma
Research

Linear devices, LHD,
Foreign devices(University, NIFS,
JAEA)

Foreign devices, LHD,
JT-60SA(University, NIFS,
JAEA)

Mainframe computer(University, NIFS,
JAEA)

Understanding ofphysical mechanism
which dominate
divertor operation

Verification andvalidation of
detachment plasmaLack of knowledge
about property andforming condition of
detachment plasmas

Lack of understanding
to control radiative
detachment plasmas
steadily

Progress since 2005
"Future Fusion R&D"

Plasma operation
scenario
Necessity of divertor detachment(heat load reduction, mass loss
mitigation)

ReactorDesignReactor designing
team(JAEA, NIFS)

Linear devices, Heatload test-stand, LHD(University, NIFS,
JAEA)

Linear devices, LHD(University, NIFS)

Development oftheoretical modelingfor detachment plasma

Decision of consistentfusion output withdivertor heat flux

Understanding of heatremoval property ofdivertor components(steady & transient)

Uncertainty ofdetachment plasma
prediction

Inconsistent fusion
output with acceptabledivertor heat flux

Insufficient heatremoval property withconventional coolingsystemNot yet undertaken

Fundamental
research, LHD(NIFS, JAEA)

Understanding ofmaterial property ofplasma facing
components

Improvement ofresistance to neutron
irradiation of copper
alloy

Understanding ofhydrogen behavior on
plasma facing
components

Clarification ofrequired particle
exhaust properties

No adequate materials
to use under high-heatflux and high-neutron
flux conditions

Uncertainty of usageof copper alloy as
divertor materials

Lack of understanding
to predict particle
balance in DEMO
reactorLack of knowledge
about required particle
exhaust property

Heat removal property
Decision to choose
tungsten as a plasma target
materials in ITER divertor

Fig. 4.

Cu：~ 10 MW/m

Material development
2

F82H：~5 MW/m2

Application limits under neutron
irradiation in Cu alloy: ~ 1 dpa

Structure of issues in “Divertor”
59

Not yet undertaken

Particle exhaust

No major candidate of vacuum
pump for DEMO reactor

Hea7ng+and+Current+Drive+Systems
Providing+hea7ng+and+current+drive+system+required+for+DEMO

Demonstra7on+of+NBI+system+for+DEMO
Demonstra7on+of+ECH+system+for+DEMOAssessment of the Transition
Condition(2027)

NBI+mock:up+test+facility+
To+develop+integrated+performance+
Integra7on+of+element+performance+

Intermediate
C&R (2020)

JAEA,+NIFS+

JAEA,+NIFS+

JAEA,+NIFS+

To+establish+beam+focusing+technology+
required+for+installing+the+
neutron+shield+structure+in+beam+line+

To+develop+
high:eﬃciency+
neutralizer+

To+develop+electrode+material+with+low+
work+func7on+

Low+eﬃciency+
of+neutralizer

Necessity+of+Cs:free+ion+sourceConcern+of+performance+
degrada7on+of+ion+source+by+neutron+streaming+
from+beam+line

Maintenance+

JAEA,+NIFS,+Univ,+
Industries+

JAEA,+NIFS,+Industries+

JAEA,+NIFS+

JAEA,+NIFS,+JT:60SA+

To+develop+mul7ple:stage+energy+recovery+
technology+

To+develop+mirror:less+waveguide:injector:
type+launcher+system+

To+develop+fast+variable+frequency+
technology+

To+develop+gyrotron+
with+higher+frequency+

Necessity+of+
improvement+of+
eﬃciency+of+gyrotron

Minimiza7on+of+
occupied+volume

Diﬃculty+of+
installa7on+of+
steerable+mirror

Necessity+of+higher+
frequency+than+ITER

Development+of+ECH+R&D+plan

Development+of+NBI+R&D+plan
ITER+

ITER+

To+develop+high:voltage+power+supply+
and+bushing+

To+complete+ITER+ECH+
system+JAEA+

To+develop+large+bore+
ceramic+insula7ng+
material+

To+clarify+technological+
speciﬁca7ons+of+hea7ng+
and+current+drive+systems+

To+develop+RF+type+ion+
source+Roles+of+NBI+and+ECH,+and+
power+ra7o+of+them+are+
undeﬁned

+ITER+NBI+system+is+under+developing+

ITER+ECH+system+is+under+developing+
Reactor+Design+
Diagnos7cs+and+Control+System+
Reactor+Plasma+Research+

Progress since2005 “Future
Fusion R&D”

Enhanced+performance+of+gyrotron

Enhanced+performance+of+nega7ve+ion+source+

Fig. 5.

Structure of issues in “Heating and Current Drive Systems”
60Theory+and+Numerical+Simula7on+Research
Establishment+of+physics+and+engineering+bases+for+fusion+reactor

JAEA,+NIFS,+Universi7es+and+industrials+(DEMO+
design+and+analysis)

Real+7me+
process

Improvement+of+opera7onal+control+actuator+
Improvement+of+control+logic+and+actuators+etc

Development+of+integrated+fusion+reactor+code+
Design+integra7on+as+a+power+plant+etc
It+is+necessary+to+improve+predic7on+capability+of+
behavior+of+power+plant.+

JAEA,+NIFS,+Universi7es+and+industrials+(modelling)

DEMO+
designIt+is+necessary+to+develop+opera7on+scenario+in+
power+plantDiagnos7cs+
and+controlmodeling/scaling
Predic7on+of+DEMO+plasmaPredic7on+of+controllability+in+plantProviding+the+data+necessary+for+examina7on+of+DEMO+
opera7on+scenario

JAEA,+NIFS,+Universi7es+(theory+and+simula7on)

JAEA,+NIFS,+Universi7es+(DEMO+design+and+analysis)

JAEA,+NIFS,+Universi7es+(modelling)

Development+of+integrated+DEMO+plasma+simula7on+code+
control+logic,+actuators+etc
It+is+necessary+to+improve+predic7on+capability+for+
DEMO+plasma+integra7on
Development+of+integrated+code+for+DEMO+
Control+logic+and+actuators+etc

Fusion+plasmaReproduc7on+and+predic7on+of+burning+fusion+plasma
JAEA,+NIFS,+Universi7es+(theory+and+simula7on)
Development+of+integrated+burning+fusion+plasma+simula7on+code+
α+par7cle+hea7ng,+instability+triggered+by+high+energy+par7cle+etc
It+is+necessary+to+improve+predic7on+capability+of+
burning+fusion+plasma+

Providing+boundary+
condi7ons

Fusion+plasmaIt+is+necessary+to+improve+predic7on+capability+of+
controllability+in+energy+plant+

JAEA,+NIFS,+Universi7es+(DEMO+design+and+analysis)

JAEA,+NIFS,+Universi7es+(modelling)

It+is+necessary+to+improve+predic7on+capability+of+
basic+behavior+in+energy+plant+

JAEA,+NIFS,+Universi7es+(DEMO+design+and+analysis)

Fusion+plasmaDevelopment+of+opera7onal+control+simulator+
which+enables+to+predict+plant+behavior
Real+7me+process+etc

Improvement+of+base+code+for+DEMO+
Expansion+of+man:machine+interface+and+
improvement+of+model

JAEA,+NIFS,+Universi7es+(theory+and+simula7on)

It+is+necessary+to+improve+predic7on+capability+for+
fusion+plasma,+in+order+to+minimize+design+margin+
which+should+be+considered+in+DEMO+design+

It+is+necessary+to+develop+opera7on+scenario+in+
DEMO

Development+of+real+7me+simulator

Predic7on+of+basic+behavior+of+the+plantProviding+boundary+
condi7ons

DEMO+
designPredic7on+of+basic+behavior+in+energy+plant

Reproduc7on+and+predic7on+of+fusion+plasmaDevelopment+of+integrated+fusion+plasma+simula7on+code+
MHD,+microinstability,+macroinstablity,+atomic+
and+molecular+process,+plasma+material+
interac7on+etc

Improvement+of+opera7onal+control+simulator+
Control+logic+and+actuators+etc

Improvement+of+interface+of+engineering+codes+(combina7on+with+thermal+analysis,+electromagne7c+force+analysis,+stress+analysis,+neutronics+analysis)+
Development+of+engineering+code+such+as+
molecular+dynamics+analysis+in+materials
It+is+necessary+to+improve+predic7on+capability+for+basic+behavior+in+plant+

DEMO+
designIt+is+necessary+to+examine+opera7on+scenario+in+
DEMO

Fig. 6.

Structure of issues in “Theory and Numerical Simulation Research”
61

Assessment of
the Transition
Condition(2027)

Diagnos7cs+
and+controlIntermediate C&R
2020

DEMO+
designDevelopment+and+integra7on+of+each+engineering+codeImprovement+and+integra7on+of+fusion+plasma+code+model

Diagnos7cs+
and+controlProgress since 2005
“Future Fusion R&D”

Reactor+Plasma+Research
Assessment of theTransition Condition(2027)

Establishment+of+burning+plasma+control+for+DEMO
ITER,+REC+
To+realize+non:
induc7ve+steady:state+
opera7on+with+Q>+JAEA,+NIFS,+Univ.+

JT:60SA+

To+develop+control+
simulator+

To+demonstrate+integrated+
plasma+performance+to+be+
extrapolated+to+DEMO+

Necessity+of+development+
of+control+logic+under+the+
condi7on+where+available+
diagnos7cs+are+restricted+
in+DEMO

Diagnos7cs+and+
Control+System+

To+demonstrate+burning+control+in+self:
hea7ng+regime+

Necessity+of+integra7on+of+
element+performances

Theory+and+Numerical+
Simula7on+
Research+

Characteris7cs+of+self:
regula7ng+burning+
plasma+is+under+
inves7ga7on

ITER,+REC+

Blanket+Characteris7cs+of+
burning+plasma+is+under+inves7ga7on

Divertor+

Prospect+for+ensuring+device+integrityProspect+for+control+technique+of+steady+fusion+output

JT:60SA+

JT:60SA,+ITER+

JT:60SA,+ITER,+LHD+

JT:60SA,+ITER+

JT:60SA,+ITER+

To+demonstrate+high:beta+
steady:state+opera7on+

To+demonstrate+high+density+opera7on+with+high+conﬁnement+

To+demonstrate+par7cle+
control+technique+(D,+T,+
He,+Impuri7es+To+demonstrate+
opera7on+with+out+
large+ELMs+

To+demonstrate+control+
technique+of+disrup7on+

Conﬁnement+degrada7on+
in+high+density+regime

Necessity+of+detached+opera7on

Necessity+of+reduc7on+of+ELM+pulse+heat+loadUnmi7gated+disrup7on+
is+unacceptable

Necessity+of+high+beta+
opera7on+with+over+no:
wall+beta+limit+without+in:vessel+control+coils

Fuel+System+

Divertor+
ITERJT:60SA,+
Domes7c+device+on+
plasma+and+divertor+
experiments+

Intermediate C&R
2020

JAEA,+NIFS,+Univ,+ITPA+
To+develop+physics+
model+and+to+promote+further+development+of+
performance+predic7on+codes+
Theory+and+Numerical+
Simula7on+
Research+
Progress since2005 “Future
Fusion R&D”

Assessment+of+feasible+
integrated+performance+
is+not+suﬃcient

JAEA,+NIFS,+Univ,+ITPA,+
oversea+devised+

Reﬂect+on+JT:60SA/ITER+research+plans

To+develop+DEMO+
physics+DB+

PWI+basic+data+on+
Tungsten+is+not+
suﬃcient+

JAEA+

Extrapola7on+of+
exis7ng+DB+to+DEMO+
is+not+suﬃcient

To+obtain+PWI+basic+
data+on+Tungsten+

To+develop+physics+design+and+
to+iden7fy+reactor+parameters+

ITER,+JT:60SA,+LHD,++
Oversea+devices+
To+clarify+issues+on+
Tungsten+divertor+
property+for+long+7me+
Inﬂuence+of+high+heat+
ﬂux+on+Tungsten+material+is+not+clariﬁedDivertor+

Necessary+of+compa7bility+
between+DEMO+objec7ve+and+
reactor+engineering+constraints

Reactor+Design+REC:+Remote+Experimenta7on+Centre

Progress+of+ITER+physics+
modeling+ITER+(ITPA)

Expansion+of+ITER+
physics+DB+(ITPA)

Fig. 7.

Progress+of+ITER+
physics+design

Genera7on+of+compact+
and+high+power+DEMO+
concept+(SlimCS)

Progress+of+real+7me+control+technologies+(NTM,+Ti,+Vφ,+J)+in+JT:60U+
Development+of+high+beta+regime+over+free+boundary+MHD+limit+in+JT:60U+
Acquisi7on+of+plasma+response+property+data+in+JT:60U

Structure of issues in “Reactor Plasma Research”
62

Fuel+Systems
Establishment+of+technical+bases+for+fuel+cycle+system+in+DEMO

Large+scale+facility

Large+scale+facility

Large+scale+facility

Establishment+of+
technologies+for+fuel+cycle+
system+in+DEMO

Establishment+of+
technologies+for+safety+
tri7um+handling+in+DEMO

Establishment+of+
manufacturing+technologies+
for+equipment+trea7ng+
tri7um+in+DEMO

It+is+necessary+to+verify+
technologies+for+fuel+cycle+
system+with+large+scale+handling+

Assessment of theTransition Condition(2027)

It+is+necessary+to+
accumulate+the+safety+
tri7um+handling++
experiences+in+large+scale+facility+

Lithium+plant
Accumula7on+of+plant+
opera7on+experiences+It+is+necessary+to+establish+
the+technology+for+securing+lithium+6+

Integrated+veriﬁca7on+of+
equipment+(including+
generator+system)+trea7ng+
tri7um+contained+gas+and+
water+is+necessary+Blanket+Divertor+
SafetyFusion+plasma

ITER

ITER

ITER

Veriﬁca7on+of+speciﬁca7ons+
for+fuel+cycle+system

Veriﬁca7on+of+technologies+
for+fuel+cycle+system+in+
DEMO

Veriﬁca7on+of+technologies+
for+tri7um+safety+handling+
and+accumula7on+of+its+
experiences

Accumula7on+of+
experiences+of+equipment+
opera7on+trea7ng+tri7um

It+is+necessary+to+verify+
integrated+system+
technology+for+fuel+cycle+
system+in+reactor+

It+is+necessary+to+
accumulate+experiences+of+
tri7um+safety+handling+in+
reactor+It+is+necessary+to+verify+
equipment+(fuel+system)+trea7ng+tri7um+contained+
gas+and+water+

It+is+necessary+to+verify+
fuelling+scenario+

Intermediate C&R
2020

Large+scale+facility

Lithium+plant

Construc7on+of+
large+scale+facility+

Establishment+of+concept+for+
lithium+6+plant+

It+is+necessary+to+
establish+large+
scale+handling+technology+

It+is+necessary+to+verify+the+technology+for+securing+lithium+6+

Blanket+Divertor+
SafetyEstablishment+of+concept+for+fuel+cycle+system

Fusion+plasmaTPL/JAEA+Rokkasho/+
University+of+Toyama

TPL/JAEA+Rokkasho/+
University+of+Toyama

TPL/JAEA+Rokkasho/+
University+of+Toyama

Determina7on+of+
speciﬁca7ons+of+fuel+cycle+
system+Establishment+of+
technologies+for+fuel+cycle+
systemEstablishment+of+
technologies+for+safety+
tri7um+handling

Accumula7on+of+data+base+for+development+of+
equipment+trea7ng+tri7um

It+is+necessary+to+deﬁne+
fuelling+scenario+and+
es7mate+fuel+inventory+

It+is+necessary+to+develop+
component+technologies+
such+as+impurity+removal+
and+isotope+separa7on+

It+is+necessary+to+verify+
technologies+for+detri7a7on+
system+and+quality+control+

It+is+necessary+to+obtain+
basis+data+such+as+tri7um+
materials+interac7ons+

Progress since 2005
“Future Fusion R&D” Design+of+ITER+system

Development+of+technologies+for+ITER+
system

Accumula7on+of+safety+tri7um+handling+experiences+
and+data+in+TPL/Rokkasho

Fig. 8.

JAEA+Rokkasho

It+is+necessary+to+develop+
securing+technology+for+
lithium+6+used+for+tri7um+
breeding+	

TPL+(tri7um+process+laboratory+placed+in+JAEA+Tokai

Structure of issues in “Fuel Systems”
63

Hea7ng+and+current+drive

JAEA+DEMO+design+group
Examina7on+of+process+for+securing+ini7al+loading+tri7um+Examina7on+of+process+to+secure+lithium+6.+

JAEA+DEMO+design+group

Prepara7on+of+start:up+
scenario+without+ini7al+loading+tri7um+
It+is+necessary+to+examine+
start:up+scenario+without+
ini7al+loading+tri7um+

Veriﬁca7on+of+technology+and+accumula7on+of+experience+for+fuelling+cycle+system

ITER/JT:60SA

ITER

It+is+necessary+to+examine+
the+produc7on+process+for+securing+tri7um+(collec7on+from+heavy+water+
atomic+reactor+and+
reprocessing+facili7es,+
import)Material+Development+and+Establishment+of+Codes+and+Standards+
Validation of reliability under high-dose
irradiation

Standardization of structural material for DEMO
blanket

Availability
rate andmaintainability

Assessment of theTransition Condition
To present technical specifications of(2027)

To understand
irradiation-induced
degradations

JAEA(DEMO designteam), Industries
To present technicalspecifications of blanket
structural materials for
DEMO fusion reactor
No technicalspecifications of blanket
structural materials for
DEMO fusion reactor

JAEA(BA-Rokkasho),Helios (Rokuchan),
NIFS(Fusion Tech.
Project), University’s
Fusion Material’s
Facilities(HVEM@Hokkaido U.,
Oarai-RI facility@Tohoku
U.,
DuET&MUSTE@Kyoto U.
etc.)

International/domestic
academic societies
To standardize small
specimen testing
technologies (SSTTs).

ITERTBMInternational/domestic
academic societies
JAEA, Industries (Metalprocessing)

To initiate preparatory
activities for materials
standardization inacademic societies andso on

To establish massproduction technologies of
RAF steelTo establish blanket
structure fabrication
technologies

Mass-production
technologies has not been
establishedBlanket structure
fabrication technologies
have not been establishedNo standard on blanket
structural materials

Progress in joining
technologies (HIP,
welding)

Kicking-off in preparatory
activities for material
standardization

Experiences inlarge-scalemelting

High-dose Irradiation
database is not validated

To standardize small
specimen testing
technologies (SSTTs)

Baseline of No clear specification
expected to DEMO fusion
DEMO design reactor materials

Progresssince 2005
“FutureFusion R&D”

DEMO
conceptual
designTo validate the 80 dpa
irradiation data by using
fission reactor

Irradiation database has
not been evaluatedsufficiently

To clarify requests to thestructural materials for
DEMO fusion reactor

JAEA, Industries (Steel)

Fusion neutron Irradiation
database has not been
evaluated sufficiently

HFIR, JAEA (BARokkasho)

To obtain data of joining/coating, effect ofelectromagnetic force,compatibility with
coolants, and theirradiation effect on theseproperties

JAEA(DEMO designteam), Industries

Intermediate C&R(2020)

Availability
rate andmaintainability

JAEA (BA-Rokkasho)
NIFS(Fusion Tech.
Project), Universities,
JOYO, JMTR, HFIR etc.

To clarify requests to the structural
materials for DEMO fusion reactor.

DEMO
conceptual
designStatement ofavailability ofadvanced materials

To clarify fusion neutron
irradiation effect

blanket structural materials for DEMO
fusion reactor

DEMO
conceptual
designBasic requirement
for structural design

IFMIF, Intense fusion
neutron sources

JAEA (BA-Rokkasho)
NIFS(Fusion Tech.
Project), Universitiesetc.

To obtain data of joining/coating, effect ofelectromagnetic force,and compatibility with
coolants

Unirradiated materials
properties has not been
evaluated sufficiently

No available standards on
SSTTs

JAEA (BA-Rokkasho)
NIFS(Fusion Tech.
Project), Universities,
JOYO, JMTR, HFIR etc.
To establish the validity ofmaterial data obtained by
SSTT
Validity of material dataobtained by SSTT is
unclear

HFIR, JAEA (BARokkasho)

To obtain 80 dpa
irradiation data by using
fission reactor
Material properties at highdose irradiation has notbeen evaluated sufficiently

Fusion neutron sources
To enhance
understanding of the
impact of transmutation
helium using fusion
neutron source
Understanding of helium
effect is insufficient due tothe lack of volumetricirradiation source inJapan

Enhancement of materials irradiation database andprogress in understanding mechanism of irradiationinduced degradation

Enhancement ofmaterials databaseProgress in R&D of reduced-activation ferritic steelFig. 9.

Structure of issues in “Material Development and Establishment of Codes and Standards”
64

JAEA, 
NIFS, Universities, etc.

To establish degradation
models based onirradiation-field correlation
theoryTo clarify the uses ofadvanced materials andto enhance the material
databaseMechanism of irradiationinduced degradation isstill unclear

Utilization of advanced
materials is unclear anddatabase is insufficientProgress in R&D ofadvanced materials

Safety+of+DEMO+Reactor++
and+Safety+Research

Guideline+to+ensure+DEMO+
plant+safety+and+consistent+
design+condi7ons

Guidelines+for+both+plasma+
control+and+securing+soundness+of+in:vessel+components

Standards/Criteria+
Reactor+Design+

JAEA, industry, academic
societies, NIFS, universities
Safety+assessment+of+DEMO+plant
Assessment+supported+by+V&V+
ac7vi7es+is+required

JAEA, NIFS, universitiesEstablishment+of+guideline+to+ensure+DEMO+plant+safety+

Assessmentof theITER, JT-60SA, LHDTransition
Condition! Establishment+of+failure+(2027)
scenario+of+in:vessel+

component+! Assessing+damage+of+in:
vessel+components
Experiences+and+achievements+
through+plasma+experiments+

Reactor+Plasma+
Research+
Intermediate C&R
2020

JAEA, industry, NIFS,
universities

JAEA, industry, NIFS,
universities

Development+of+computer+simula7on+codes+for+safety+analysis

Development+of+computer+
simula7on+codes+to+
es7mate+damage+of+in:
vessel+component+by+
plasma

Code+development+is+
diﬃcult+to+ﬁt+for+research+
mo7ve+

Damage+of+in:vessel+
components+by+plasma+is+
not+fully+understood+

Theory+and+Numerical+
Simula7on+Research+

Material+
Development+

Experimental facilities tostudy transient phenomena
in DEMO plant
V&V+experiments
! V&V+ac7vi7es+are+interrupted+! There+is+no+ac7ve+V&V+
facility+

JAEA, industry, NIFS,
universities
Arrangement+of+safety+
characteris7cs+of+DEMO+
plant+
Analysis+using+exis7ng+
computer+simula7on+codes

Proposal+of+guideline+to+ensure+DEMO+plant+safety

JAEA, industry, NIFS,
universities
Arrangement+of+safety+related+engineering+issues
It+is+necessary+to+inves7gate+characteris7c+issues+of+DEMO+
plant+taking+account+of+achievements+in+the+ITER+project+
Progress since2005 “Future
Fusion R&D”

The+French+Nuclear+Safety+Authority+has+accepted+DAC+Demande+d’Autorisa7on+de+Crea7onﬁles+including+
RPrS(Rapport+Preliminaire+de+Surete)+and+Impact+study+report,+and+The+decree+authorizing+the+crea7on+of+the+
ITER+nuclear+facility+has+been+signed.+Technical+prescrip7ons+have+been+agached+on+the+authoriza7on+decree.+Fig. 10. Structure of issues in ”Safety of DEMO Reactor and Safety Research”
65

Proposed+guideline+shall+be+
accepted+by+the+society+

JAEA, ITER
! Assessment+of+environmental+behavior+of+
tri7um+! Assessment+and+control+of+
tri7um+release+to+the+environment+! Outcomes+from+ﬁssion++ﬁeld+can+par7ally+be+used.+! Outcomes+in+EU+ac7vity+
can+par7ally+be+used.
! Few+Researchers+in+the+safety+ﬁeld

Availability+and+Maintainability
Demonstra7on+of+prospect+of+
availability+rate+and+economical+
eﬃciency+in+commercial+fusion+reactors+

Demonstra7on+of+
remote+maintenance
Assessment of the Transition
Condition (2027)

Prospect+of+maintenance+cycle,+availability+rate+
and+back+end
Divertor
Material+Development+
and+Standards+/+Criteria+(Life7me+
predic7on)

ITER,+SA+
Technological+
accumula7on+of+remote+handling,+inspec7on+and+
maintenanceRequired+for+agachment,+
maintenance+and+
replacement+of+large+and+
complicated+components

DEMO+design+team
Inves7ga7on+and+
op7miza7on+of+
maintenance+process,+
reactor+shutdown+period+
and+back+end+
Detailed+inves7ga7on+of+
maintenance+process,+
cycle+and+waste+handling+
must+be+promoted+by+
involving+R&D+results+and++technological+
accumula7on+in+ITER,+SA+
etc

Intermediate C&R(2020)

Prospect+of+maintenance+techniques+

JAEA,+industry,+
universi7es

JAEA,+universi7es,+
Industry+(New+facility)++
Development+on+
large:scale+maintenance+techniques+for+DEMO+

Standard+deﬁni7on+for+
disposal,+reuse+and+clearance+of+radioac7ve+
wastesStandard+deﬁni7on+is+
required+for+inves7ga7on+of+back+end+e.g.+disposal+building,+storage+site,+burial+method+etc

Development+and+demonstra7on+of+
maintenance+and+
replacement+techniques+
newly+required+for+
DEMO+are+necessary+

DEMO+design+teamShowing+of+feasibility+of+maintenance+method+
and+determina7on+of+DEMO+R&D+items+and+targets+are+requiredSuperconducting Coils
Blanket
DivertorConstruc7on+of+basic+concept+of+DEMO+design,+
structure+and+parameters

Handling+and+inspec7on+of+
equipment+as+nuclear+facility+are+requiredIndustry+(Maintenance+technologies+
for+ﬁssion+reactors)
Progress since 2005 “Future
Fusion R&D”

JAEA,+universi7es,+
Industry+(Exis7ng+
facility)++
Development+on+
func7onal+materials+
and+devices+aiming+for+
200+MGy

Building+of+database+of+failure+rates+
Required+for+predica7on+
of+unplanned+shutdown+
and+mi7ga7on+

Required+for+more+sophis7cated+and+
eﬃcient+remote+maintenance

Inves7ga7on+and+selec7on+of+components+to+be+
maintained,+techniques+and+working+process

ITER+
Handling+of+radioac7ve+large+
components,+hot+cell,+decontamina7on,+inspec7on+and+
repair+of+devices,+detailed+inves7ga7on+on+waste+disposal,++detailed+design+of+equipment+and+building

ITERSA++
Hea7ng+and+Current+
Drive+System

(Remote+and+
robot+technologies)
Industry+

Reactor Plasma
Research

DEMO+design+team
Determina7on+of+maintenance+method,+reactor+
structure+and+parametersSelec7on+of+reactor+structure+and+maintenance+
method+considering+consistency+with+plasma+
control+and+equipment+design+is+required+

Explora7on+of+DEMO+conceptual+designs+with+
diﬀerent+features+and+extrac7on+of+issues+(JAEA,+BA,+industry(CRIEPI))

Development+of+remote+maintenance+techniques+for+ITER+(JAEA,+ITER,+industry)

Fig. 11. Structure of issues in “Availability and Maintainability”
66

Development+of+func7onal+materials+and+
devices+aiming+for+integrated+dose+of+100+
MGy+during+ITER:EDA+(JAEA,+ITER,+industry)

Diagnos7cs+and+Control+Systems
Providing+diagnos7cs+and+control+equipment+required+for+DEMO
JT:60SA,+ITER+
To+establish+prac7cal+and+
reliable+control+logic+
Reactor+Plasma+
Research+

Assessment of the Transition
Condition (2027)

Necessity+of+op7miza7on+of+control+logic
JT:60SA,+ITER+
To+validate+simulator+
using+experimental+
data+

Prospect+for+diagnos7c+system+to+be+applicable+to+DEMOValida7on+of+
simulator+is+needed
JT:60SA,+LHD,+ITER,+Interna7onal+collabora7on+
To+develop+diagnos7cs+and+
their+analysis+codes+using+plasma+experimental+device+
Reactor+Plasma+
Research+

Development+of+diagnos7cs+
with+speciﬁca7on+required+for+control+

Irradia7on+test+facility+

JT:60SA+

To+develop+radia7on:
proofed+components+in+
parallel+with+evalua7on+
of+life7me+of+diagnos7cs+

To+show+prospects+for+
accuracy+of+equilibrium+
control+under+DEMO+
relevant+electro:
magne7c+condi7on+

Degrada7on+of+capability+
by+gamma:ray+and+
neutron+irradia7on

Large+impact+of+eddy+
current+on+magne7c+
measurements

JT:60SA+
To+develop+real:7me+
opera7onal+control+
simulator+
Real:7me+working+is+needed

JAEA,+NIFS,+Univ.+
Theory+and+Numerical+
Simula7on+Research+

To+develop+opera7on+
control+simulator+

Reactor+Design+

Necessity+of+building+control+logic+under+DEMO+
condi7on+where+available+
diagnos7cs+are+restricted

Theory+and+Numerical+
Simula7on+Research+
Reactor+Plasma+Research+

Intermediate
C&R (2020)

deﬁne+target+performance+of+diagnos7cs

JAEA,+NIFS+

ITER,+JT:60SA,+LHD,+ITPA+JAEA,+NIFS+

To+focus+diagnos7cs+
to+be+applicable+to+
DEMO+and+deﬁnitely+
needed+for+opera7on+
control+

To+accumulate+data+of+
plasma+response+
property+for+use+of+model+valida7on+

To+deﬁne+opera7on+
standard+point+and+surrounding+allowable+
opera7ng+regime+

Reactor+Plasma+
Research+

Available+diagnos7cs+
are+restricted+due+to+large+irradia7on+ﬁeld+
Progress since 2005
“Future Fusion R&D”

Reﬂect+on+JT:60SA/ITER+research+plans

Reactor+Design+

Ac7vity+of+ITER+diagnos7cs+R&D+(ITPA)

Modeling+is+insuﬃcient+
for+temporal+evolu7on

Theory+and+Numerical+
Simula7on+Research+
Reactor+Plasma+
Research+

Progress+of+real+7me+control+technique+(NTM,+Ti,+Vφ,+J)+in+JT:60U+
Acquisi7on+of+plasma+response+property+data+in+JT:60U

Fig. 12. Structure of issues in “Diagnostics and Control Systems”
67

Need+to+clarify+opera7on+
margin+and+opera7onal+
control+range+of+
detached+plasma

Reactor+Plasma+
Research+
Reactor+Design+

Table 2

Sectors in charge and necessary facilities for “Superconducting Coils”
ITER

BA

JT(60SA

OthersSuperconduc*ng,coil,system,pre3
conceptual,design,.,
Lessons,learned,from,construc*on,

.,Output,of,design,study

.,Lessons,learned,from,construc*on,

/,JAEA,(DEMO,design,team),

Decision,on,superconduc*ng,coil,system,R&D,strategy

.,Lessons,learned,from,construc*on,,.,Lessons,learned,from,construc*on,,/,
JAEA,,NIFS,,universi*es,,industry

U*liza*on,of,ReBCO,/,
JAEA,,NIFS,,ISTEC,,
universi*es,,industry,,collabora*on,with,other,ﬁelds,

Extend,produc*on,length,of,Nb3Al,
strand,/,
JAEA,,NIFS,,NIMS,,,
industry,,collabora*on,
with,other,ﬁelds

Improve,Jc,of,Nb3Sn,strand,.,
actual,performance,data,,

/,JAEA,,NIFS,,industry,,

High,strength,structural,material,
development,.,
actual,performance,data,,

/,JAEA,,NIFS,,NIMS,,
universi*es,,industry,,

Insula*on,material,development,.,
actual,performance,data,,

/,JAEA,,NIFS,,universi*es,,industry,,/,
JAEA,,NIFS,,universi*es,,industry,,,
16,T,class,test,facility,will,
be,needed,

Conductor,performance,
improvement,-,
Lessons,learned,from,opera*on,

Superconduc*ng,coil,system,
conceptual,design,-,
Lessons,learned,from,opera*on,

/,JAEA,(DEMO,design,team),/,
JAEA,(DEMO,design,team),

Final,selec*on,of,materials,to,be,used,-,Lessons,learned,from,construc*on,,

Cost,es*ma*on,of,superconduc*ng,
coil,system,

Table 3

Not4yet4
launched

-,Lessons,learned,from,construc*on,

/,JAEA,(DEMO,design,team),

Sectors in charge and necessary facilities for “Blanket”
ITER

BA

Arrangement,of,basic/reference,data,
Demonstra*on,of,integrated,func*ons,of,blanket,
system,in,fusion,environment,

JT(60SA

OthersNot4yet4
launched
JAEA1extension,of,facili*es2,-,

JAEA1addi*on,and,
extension,of,facili*es2,/Arranged,data,base,for,use,in,the,design,ac*vi*es,

JAEA1addi*on,and,
extension,of,facili*es2,-Test,plans,for,TBM,system,and,addi*onal,test,
facili*es

JAEA

Conﬁrma*on,of,soundness,to,heat,and,pressure,loads,,and,of,response,to,EM,loads

JAEA1addi*on,and,
extension,of,facili*es2,-Valida*on,of,design,and,manufacturing,
technologies,to,develop,blanket,system/JAEA,,
ManufacturersDesign,and,schedule,of,irradia*on,and,tri*um,
experiments,

/

JAEA

Understandings,of,tri*um,behavior,,establishment,of,tri*um,technology/

JAEA1addi*on,and,
extension,of,facili*es2,

Validated,reference,data,base,,,data,base,suppor*ng,design,standards

/

JAEA1addi*on,and,
extension,of,facili*es2,

Design,of,blanket,system

JAEA

<Advanced,blanket,R&D,for,DEMO3TBM>,• Fabrica*on,of,small,test,devices,and,separate,
examina*on,on,func*ons,and,,proper*es,• Experiments,on,blanket,opera*ons,with,reactor,
condi*ons,u*lizing,Integrated,circula*on,loop,
system,• Technological,inves*ga*on,on,power,genera*on,
systems,and,R&D,on,heat,exchange,• Inves*ga*on,on,design,,oﬀering,of,preliminary,
design,and,their,comparison/Universi*es,,NIFS,,.,JAEA• Expansion,of,fundamental,and,standard,data,• Integrated,demonstra*on,with,small,mock3up,,/,Universi*es,,NIFS,.,JAEA

68

Table 4

Sectors in charge and necessary facilities for “Divertor”
ITER

BA

JT(60SA

OthersModeling,of,detachment,plasma,

.,

/

.,

.NIFS

Veriﬁca*on,and,valida*on,of,detachment,plasma,/..NIFS

Op*miza*on,of,divertor,conﬁgura*on,/Consistent,fusion,output,with,divertor,heat3ﬂux,/Improvement,of,neutron,irradia*on,resistance,of,copper,alloy,
Material,property,of,plasma,facing,materials,

Not4yet4
launched

.
.,

.,

Maintenance,scenario,for,divertor

/.NIFS,,University
.NIFSDevelopment,of,innova*ve,cooling,system.

Development,of,feasible,vacuum,pump,under,
DEMO,reactor,condi*ons.Table 5

Sectors in charge and necessary facilities for “Heating and Current Drive Systems”
ITER

To,develop,NBI,&,ECH,systems,for,ITER,
To,clarify,technological,speciﬁca*ons,of,hea*ng,
and,current,drive,systems,BA

JT(60SA

Others

/

/,
JAEA,

.,
Reﬂect,achievement,

/,
JAEA,

To,establish,beam,focusing,technology,required,for,installing,the,neutron,shield,structure,in,beam,line,/,
JAEA,,NIFS,

To,develop,high3eﬃciency,neutralizer,/,
JAEA,,NIFS,

To,develop,electrode,material,with,low,work,
func*on,/,
JAEA,,NIFS,

To,develop,integrated,performance,of,mock3up,NBI,.,
Reﬂect,achievement,

To,develop,mul*ples3stage,energy,recovery,
technology,for,gyrotron,.,
Reﬂect,achievement,

.,Reﬂect,achievement,

/,NBI,mock3up,test,
facility,/,
JAEA,,NIFS,,
Industries,

To,develop,mirror3less,waveguide3injector3type,launcher,system,/,
JAEA,,NIFS,

To,develop,fast,variable,frequency,technology,
To,develop,gyrotron,with,higher,frequency,.,
JAEA,,NIFS,

Not4yet4
launched./,
JAEA,,NIFS,/,
JAEA,,NIFS,,,
Univ.,Tsukuba,,
Industries,.,
Reﬂect,achievement,

69

Table 6

Sectors in charge and necessary facilities for “Theory and Numerical Simulation
Research”
ITER

BA

JT(60SA

OthersNot4yet4
launched

Opera*onal,control,simulator
Upgrade,of,opera*onal,control,
simulator,.,
Valida*on,of,model

/,Organiza*on,of,ac*vi*esImprovement,of,opera*onal,control,
simulator,.,
Valida*on,of,model,/,
Organiza*on,of,ac*vi*es

Development,of,opera*onal,control,
simulator

.,Valida*on,of,model

/,Organiza*on,of,ac*vi*es

-,Valida*on,of,model

Plant,simula*on,codeDevelopment,of,integrated,fusion,
reactor,code,.,
Valida*on,of,model

/,Organiza*on,of,ac*vi*es,a`er,BA

Development,of,integrated,DEMO,code,.,
Valida*on,of,model

/,Organiza*on,of,ac*vi*es,a`er,BA

Improvement,of,base,code,for,DEMO,.,
Valida*on,of,model

Improvement,of,engineering,base,codes,
and,development,of,engineering,code,.,
Valida*on,of,model

/,Organiza*on,of,ac*vi*es,a`er,BA

-,
Valida*on,of,model
.,Code,improvement-,Valida*on,of,model

/,
JAEA,,NIFS,,
Universi*es

Fusion,plasma,simula*on,code
/,Securing,computer,resource,a`er,BA

Integrated,DEMO,plasma,simula*on,.,
Valida*on,of,model

-,Valida*on,of,model

Integrated,burning,fusion,plasma,simula*on,.,
Valida*on,of,model

-,Valida*on,of,model

/,
JAEA,,NIFS,,
Universi*es

Integrated,fusion,plasma,simula*on,.,
Valida*on,of,model

.,Valida*on,of,model

/,
JAEA,,NIFS,,
Universi*es

Table 7.,
Computer,resource/,
Securing,computer,resource,a`er,BA

Sectors in charge and necessary facilities for “Reactor Plasma Research”
ITER

To,develop,physics,design,and,to,iden*fy,
reactor,parameters,BA

JT(60SA

OthersNot4yet4
launched/To,develop,DEMO,physics,DB,.,Reﬂect,achievement

.,Reﬂect,achievement

/,
JAEA,,NIFS,,Univ.,,ITPA,,
Oversea,devicesTo,develop,physics,model,and,to,promote,further,development,of,performance,predic*on,
codes,.,
Reﬂect,achievement

.,Reﬂect,achievement

/,
JAEA,,NIFS,,Univ.,,ITPA

To,clarify,issues,on,Tungsten,divertor,property,
for,long,*me,.,Reﬂect,achievement

.,Reﬂect,achievement

/,
LHD

To,obtain,PWI,basic,data,on,Tungsten,.,Reﬂect,achievement

.,Reﬂect,achievement/,Domes*c,devicesTo,demonstrate,high3beta,steady3state,
opera*on,Oversea,devices/To,demonstrate,high,density,opera*on,with,high,conﬁnement,.,
Reﬂect,achievement/To,demonstrate,par*cle,control,technique,(D,,T,,He,,Impuri*es2

/,Reﬂect,achievement/To,demonstrate,opera*on,with,out,large,ELMs,/,
Reﬂect,achievement/

Necessity,of,securing,of,computa*onal,resourceTo,demonstrate,control,technique,of,disrup*on,/,
Reﬂect,achievement/

Necessity,of,securing,of,computa*onal,resourceTo,develop,control,simulator,.,
Reﬂect,achievement/To,demonstrate,integrated,plasma,
performance,to,be,extrapolated,to,DEMO,/,
Reﬂect,achievement/To,demonstrate,burning,control,in,self3hea*ng,
regime,/,Reﬂect,achievement

/,U*lize,ITER,REC

To,realize,non3induc*ve,steady3state,opera*on,
with,Q>4

/,Reﬂect,achievement

/,U*lize,ITER,REC

70/

Necessity,of,securing,of,computa*onal,resource
.,
LHD

/,
JAEA&NIFS

Necessity,of,securing,of,computa*onal,resource

Necessity,of,securing,of,computa*onal,resource
Necessity,of,securing,of,computa*onal,resourceTable 8

Sectors in charge and necessary facilities for “Fuel Systems”
ITER

BA

Determina*on,of,speciﬁca*ons,for,fuel,cycle,
systemVeriﬁca*on,of,speciﬁca*ons,for,fuel,cycle,system

JT(60SA

OthersNot4yet4
launched

/
/

.

Development,of,technologies,necessary,for,fuel,cycle,system

/.,
DEMO,R&D,building,in,Rokkasho

Development,of,technologies,for,safety,tri*um,
handling,/.,
DEMO,R&D,building,in,Rokkasho.,
TPL,,Univ.,of,Toyama

Development,of,equipment,trea*ng,tri*um/.,DEMO,R&D,building,in,Rokkasho.,
TPL,,Univ.,of,Toyama.,
TPL,,Univ.,of,Toyama

Construc*on,of,large,scale,facility,for,tri*um,
handling,

/,
JAEA
/,
JAEA

Development,of,technology,for,securing,lithium,6,Construc*on,of,lithium,6,plant,

/,
JAEA

Examina*on,of,process,for,securing,ini*al,loading,
tri*um,/,JAEA

Examina*on,of,start3up,scenario,without,ini*al,loading,tri*um,

Table 9

/,
JAEA

.

Sectors in charge and necessary facilities for “Material Development andEstablishment of Codes and Standards”
ITER

BA

JT(60SA

OthersEstablishment,of,mass3produc*on,
technologies,

Produc*on/
fabrica*on,
technology

Not4yet4launched	Establishment,of,blanket,structure,fabrica*on,technologies,

	

Clariﬁca*on,of,requests,to,structural,materials,for,DEMO,reactor,
Presenta*on,of,technical,speciﬁca*ons,of,blanket,structural,materials,for,
DEMO,reactor,

Preparatory,ac*vi*es,for,materials,
standardiza*on,in,academic,socie*es,
Materials,
and,so,on,
standardiza*on,Standardiza*on,of,structural,material,
for,DEMO,blanket,

Reduced3
ac*va*on,ferri*c,steel

Data,of,joining/coa*ng,,eﬀect,of,electromagne*c,force,,and,compa*bility,with,coolants,
Materials,
database,

Acquisi*on,of,80,dpa,irradia*on,data,by,using,ﬁssion,reactor,	

Data,of,joining/coa*ng,,eﬀect,of,electromagne*c,force,,compa*bility,
with,coolants,,and,the,irradia*on,
eﬀect,on,these,proper*es,

	

JAEA(BA,,Helios),,NIFS,,University’s,Fusion,Material’s,Facili*es,(HVEM@Hokkaido,U.,,
Oarai3RI,facility@Tohoku,U.,,
DuET&MUSTE@Kyoto,U.,,etc.),

Establishment,of,degrada*on,models,
based,on,irradia*on3ﬁeld,correla*on,
theory,Mechanism,of,
irradia*on3
induced,degrada*on,,
Fusion,neutron,
sourceUnderstanding,of,the,impact,of,transmuta*on,helium,using,fusion,
neutron,source,
Establishment,of,validity,of,material,
data,obtained,by,small,specimen,
tes*ng,technologies

	Standardiza*on,of,small,specimen,
tes*ng,technologies,,
Clariﬁca*on,of,fusion,neutron,
irradia*on,eﬀect,
Advanced,materials,

Clariﬁca*on,of	

Clariﬁca*on,of,the,uses,of,advanced,
materials,and,to,enhance,the,material,
database,

71

Table 10

Sectors in charge and necessary facilities for “Safety of DEMO Reactor and Safety
Research”
ITER

BA

Arrangement,of,safety,related,engineering,issues,.,
Reﬂec*on,of,achievements

/

Arrangement,of,safety,characteris*cs,of,DEMO,
plant,.,
Reﬂec*on,of,achievements/JT(60SA

OthersDevelopment,of,computer,simula*on,codes,for,safety,analysis

JAEA/,Industry/,
NIFS/,Universi*es

V&V,experiments

-,Reﬂec*on,of,achievements

Assessment,of,environmental,behavior,of,tri*um,.,
Reﬂec*on,of,achievements

JAEA/,Industry/,
NIFS/,Universi*es

Establishment,of,guideline,to,ensure,DEMO,plant,
safety,

JAEA/,NIFS/IndustryEstablishment,of,failure,scenario,of,in3vessel,
component,,Assessing,,damage,of,in3vessel,
components

/

LHD

.

Development,of,computer,simula*on,codes,to,es*mate,damage,of,in3vessel,component,by,
plasma

JAEA/,Industry/,
NIFS/,Universi*es
-,Reﬂec*on,of,achievements

Safety,assessment,of,DEMO,plant

Table 11

Not4yet4
launched-,
universi*es

JAEA/,Industry/
Academic,socie*es/,
NIFS/,Universi*es

Sectors in charge and necessary facilities for “Availability and Maintainability”
ITER

BA

JT(60SA

OthersNot4yet4launched

Determina*on,of,maintenance,
method,,reactor,structure,and,parameters

.,Japan,home,team

Inves*ga*on,and,selec*on,of,maintenance,techniques,and,working,process

.,Japan,home,team/,DEMO,design,team,(Reinforcement,of,framework),

Inves*ga*on,and,op*miza*on,of,maintenance,process,,reactor,
shutdown,period,and,back,end

.,Japan,home,team/,DEMO,design,team,(Reinforcement,of,framework),

Handling,of,radioac*ve,large,
components,,hot,cell,,decontamina*on,,inspec*on,and,repair,of,devices,,detailed,inves*ga*on,on,
waste,disposal,,,detailed,design,of,equipment,and,building/,Reﬂect,inves*ga*on,
and,design

Technological,accumula*on,of,remote,handling,,inspec*on,and,maintenance,/,
Reﬂect,experience./,DEMO,design,team,(Reinforcement,of,framework),

Construc*on,of,database,of,failure,
rates.,/,
Reﬂect,experience./,DEMO,design,team,(Reinforcement,of,framework),/,DEMO,design,team,(Reinforcement,of,framework),

Development,on,large3scale,maintenance,techniques,for,DEMO.,/,JAEA,
1Development,facility,for,large3scale,maintenance,techniques),.,Industry,,Universi*es

Development,on,func*onal,materials,
and,devices,aiming,for,200,MGy.,/,JAEA,.,Industry,,Universi*es

Standard,sejng,for,disposal,,reuse,
and,clearance,of,radioac*ve,wastes.,/,JAEA,,Industry,,.Universi*es

72

Table 12

Sectors in charge and necessary facilities for “Diagnostics and Control Systems”

ITER
To,focus,diagnos*cs,to,be,applicable,to,DEMO,
and,deﬁnitely,needed,for,opera*on,control,.,To,accumulate,data,of,plasma,response,property,
for,use,of,model,valida*on,

/

BA

JT(60SA

Others/,
JAEA,,NIFS/

To,deﬁne,opera*on,standard,point,and,surrounding,allowable,opera*ng,regime,.,
LHD,,ITPA/,JAEA,,NIFS

To,develop,diagnos*cs,and,their,analysis,codes,
using,plasma,experimental,device,/To,develop,radia*on3proofed,components,in,parallel,with,evalua*on,of,life*me,of,diagnos*cs,.,
Reﬂect,actual,achievement

To,show,prospects,for,accuracy,of,equilibrium,
control,under,DEMO,relevant,electro3magne*c,condi*on,.,/To,develop,opera*onal,control,simulator,(oﬄine),.,Reﬂect,actual,achievement/To,develop,real3*me,opera*onal,control,
simulator,.,
Reﬂect,actual,achievement/To,validate,simulator,using,experimental,data,//To,establish,prac*cal,and,reliable,control,logic,

/

/

/

.,
LHD,,Interna*onal,
collabora*on
/,
Irradia*on,test,
facility

73.,
JAEA,,NIFS

Not4yet4started