S-P3-2
Study on Maintenance, Recycle, and Radioactive Waste Management ofFusion Reactor
Part II: Whole image of radioactive maintenance target
核融合炉の保守・リサイクル・バックエンド対策に関する検討	 
２．保守対象（放射化物）の全体像	 
Takumi Hayashi
林	  	  巧Directorates of Fusion Energy Research, Japan Atomic Energy Agency
801-1, Mukouyama, Naka city, Ibaraki Pref., 311-0193, Japan（独）日本原子力研究開発機構•核融合研究開発部門 〒311-0193 茨城県那珂市向山801-1
DT fusion neutron will activate structural materials surrounding the plasma, and tritium fuel willcontaminate a lot of equipment and will spread widely in the site. The most important safety issue is how
to confine these radioactive materials. Whole image of radioactive material distribution is summarized in
the fusion DEMO reactor site.

1. BackgroundAs introduced in Part I, DT fusion neutrons
with 14MeV will activate structural materials
surrounding the plasma. Because a few kg levelof tritium will be handled in the DT fusion reactor
as a fuel, some level of tritium contamination ofvarious equipments will be considered. From thesafety point of view, to control/confine the above
radioactive materials is the most important key
issue in the fusion reactor. This part, summarizes
a whole image of radioactive materials, regarding
the maintenance and waste management.
2. Image of radioactive materials distribution
Figure 1 shows typical DEMO plant image anddistribution of radioactive isotopes (RI) materials,
such as tritium and neutron-induced one.
Activated materials by neutron mainly exist
around vacuum vessel, hot cell, and waste storage
area. Some of them become to radioactive solid
waste finally. In general, mobile activated RIs,
such as dust and corrosion products, should behandled more carefully, however, activatedequipment itself should be cared also dependingon the maintenance concept. The equipment,
which requires periodical nuclear maintenance, willbe blanket, diverter, diagnostics, tritium plants, hotcell, plasma heating, water-cooling, and airconditioning (HVAC) systems.
When thedecommissioning will be carried out, the activatedmaterials must be treated with a special attitude.
Potentially tritium contamination area will bewidely distributed in the reactor site, thoughtritium will be handled safely using multiple
confinement concept. Ventilated atmosphere inFig. 1 Typical DEMO plant image and distribution of RI (tritium& activated materials) in the site

the above all area should be cared continuously
by nuclear air conditioning systems with various
detritiation systems. Even in ITER, total area of
potentially tritium contamination is around
250,000 m 3 and the biggest one is a gallery of >70,000 m 3. The tritium is removed by catalyticoxidation with dryer or wet scrubber, as tritiatedwater.
In DEMO rector with water-coolingblanket, tritiated cooling-water should beprocessed to maintain an acceptable concentrationof tritum with the above by water detritiation
system using the improved CECE (CombinedElectrolysis and Catalytic Exchange).
3. Accountancy of radioactive materials
In order to establish stable fusion power
generation, one of key issues is how to manage thebalance of tritium production and consumption.
Accountancy of the fuel and management its
uncertainty should be considered including thosefor the various mixed wastes.

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