P3
Study on Maintenance, Recycle, and Radioactive Waste Management ofFusion Reactor
Part V : Decommissioning and radioactive waste management
核融合炉に関する検討
5．廃止措置と放射性廃棄物管理
Satoshi Yanagihara
柳原 敏
University of Fukui, Research Institute of Nuclear Engineering
3-9-1 Bunkyo, Fukui-shi, Fukui-ken, 910-8507, Japan
福井大学 附属国際原子力工学研究所 〒910-8507 福井市文京3丁目9番1号
Nuclear facilities including fusion reactors produce radioactive waste in operation and decommissioning. It
will be therefore necessary to make clear characteristics on radioactive waste arising from fusion reactors
as same as nuclear power plants. Based on the Japanese study on decommissioning and radioactive waste
management conducted in terms of nuclear power plants, a discussion has started to characterize theradioactive waste arising from decommissioning of fusion reactors. The difference on waste arising
between nuclear power plants and fusion reactors is briefly discussed at the beginning of the study.

1. Introduction
Since starting peaceful use of nuclear energy
after World War II, a number of nuclear facilities
for civilian use including nuclear power plants
have been constructed in the world. There are
more than 430 nuclear power plants (NPPs)
operating in the world. Nuclear facilities must be
managed in a safe and efficient manner throughout
their life cycle from designing through operation
to decommissioning stages. Decommissioning is
the final stage of the plant life cycle, and it is often
considered as less important since it does notproduce any values from the activities such as
decontamination and dismantling. However, thenuclear facilities ceased their operation should not
be abandoned; the site should be cleaned up to
make use for other objectives or continued use fornuclear energy. In terms of developing fusionenergy, it must be of importance to characterize
the plant life cycle before starting construction of
the facility for energy production. Waste
management is a key issue in the plant life cycle.
During the operation of fusion reactor, someradioactive waste will generate in various states,
and a large amount of radioactive wastes will begenerated from decommissioning of the facility.
The study on waste arising from decommissioning
is inevitable in research and development offusion energy.
2. Decommissioning of nuclear facilities
Decommissioning activities include planning,project management, facility characterization,decontamination, dismantling, final radiation
survey, and so on. These activities should becarried out to achieve reduction in radiologicalhazards on the basis of planning and assessment toensure safety. De-licensing is the final outcome ofthese decommissioning activities. As theremarkable characteristics, decommissioning of
nuclear power plants and fusion reactors will
result in the generation of large amount ofradioactive waste with differing types in relatively
short periods.
2. Regulation of nuclear facilities
Decommissioning NPPs is basically regulatedby the nuclear reactor regulation law which wasissued 1957. A new regulatory frame fordecommissioning has legislated by amending thelaw, which brought into effect in December, 2005.
The decommissioning phase is separated fromoperational phase. In addition, clearance system isestablished for effective recycling of the materials
arising from decommissioning.
To date, various experimental fusion facilities
have been constructed under safety regulations;the construction and operation are basicallyregulated by the other law than the nuclear reactor
regulation law as long as no nuclear fuel materials
are handled in the facility. The law applied in mostcase is the law concerning the prevention fromradiation hazards due to radio-isotopes and others.
However, it may be practicable to study the waste
arising from fusion reactors by assuming the same
frame on NPPs, even though a new regulation forfusion reactors will be prepared in the future. Herewe will discuss the waste management on fusion
reactors in the same frame as regulating NPPs.
3. Policy of radioactive waste management
Nationalpolicy onradioactive
waste
management is described in the framework fornuclear energy policy by atomic energy
commission (2005).
The four principles on treatment and disposal ofradioactive waste are described in the framework; Liability of generators,
 Minimization of radioactive waste, Rational treatment and disposal, and Implementation based on mutual understanding
with public.
The policy also states as follows; important isappropriate classifications of the wastes based on
the recognition of that the waste may include
materials with such characteristics as that it takes
an extraordinary long time for the radioactivity todecrease to insignificant levels. As for the wastes
from research and development facilities,
trans-uranium and uranium waste, discussion on
safety regulations has been undertaken step bystep. Concerned parties should work on theimplementation of disposal in line with theprogress on the preparations for the safety
regulations.
On the basis of the statement, efforts have been
made to build regulatory regime on disposal ofradioactive wastes
4. Radioactive waste disposal
Waste disposal forms are classified into twotypes; disposal with institutional control for very
low level, low level and intermediate level wastes,and geological disposal for high level andtrans-uranium wastes.
Basically, the waste will be disposed of indeeper with increasing their radioactive risk. The
wastes will be disposed of in different types ofrepository depending on radioactivity levels andits characteristics as follows.
Very low level waste (VLLW): The wastes will bedisposed of in simple near surface repository
without engineering barriers so called trench typefacility. The upper limits of activity concentration(Bq/t) are 1.0×1010 for 60Co, 1.0×107 for 90Sr,
1.0×108 for 137Cs.
Low level waste (LLW): The wastes will bedisposed of in near surface repository withengineering barrier so called concrete pit typefacility. The upper limits of activity concentration(Bq/t) are 1.0×1011 for 14C, 1.0×1015 for 60Co,
1.0×1013 for 63Ni, 1.0×1013 for 90Sr, 1.0×109 for99
Tc, 1.0×1014 for 137Cs, 1.0×1010 for all alphanuclides.
Intermediate level waste(ILW): The wastes will bedisposed of in sub-surface disposal repository 50
to 100 meters below from the surface. The upperlimits of activity concentration (Bq/t) are 1.0×
1016 for 14C, 1.0×1013 for 36Cl, 1.0×1014 for 99Tc,
1.0×1012 for 129I, 1.0×1011 for all alpha nuclides.
As for the high-level waste, vitrified canisters
will be disposed of with some trans-uranium waste
in a geological repository more than 300 meters
below the surface. A disposal business has
progress for the low-level radioactive waste in theRokkasho low level radioactive waste disposal
center since 1992.
5. Waste arising from decommissioning
The decommissioning cost regarding 1100 MWclass NPPs was studied by a government committee;
it showed the characteristics of wastes arising fromdecommissioning. On the other hand, dismantlingand disposal scenario of ITER was studied; thewaste arising was estimated assuming 30 years
cooling period after ceased operation [1]. Bothresults are shown as follows.
ITER
ILW: 7700 t, LLW: 9000 t, VLW: 3200 t
BWR
ILW: 100 t, LLW: 2000 t, VLLW: 10,000 t
PWR
ILW: 200 t, LLW: 3000 t, VLLW: 3,000 t
A large amount of intermediate level wastes will
be generated from decommissioning of ITER, whilea dominant waste class arising from BWR/PWR isvery low level; it is about 70 times of the wastes
arising from BWR. This might cause higher cost ofwaste management of ITER than that of nuclear
power plants.
6. Future perspective
It will be necessary to study more precisely on thewaste to characterize the waste management anddecommissioning of fusion reactors. This will bedone in parallel with the study on new regulatory
frame for fusion reactors.
Reference[1] S. Kakudate; Journal of Plasma and Fusion
Research, Vol. 87 Supplement, February( 2011)