29E43P
安全性に着目したD-3Heトカマク型核融合炉の概念設計
Conceptual Design of D-3He Tokamak Fusion Reactor Focusing on Safety
細川康二, 小川雄一, 岡野邦彦
HOSOKAWA Koji, OGAWA Yuichi, OKANO Kunihiko
東大新領域Graduate School of Frontier Sciences, the University of Tokyo
1. Introduction
The D-3He fusion reactor has many advantages suchas lower neutron productions and tritium inventory
compared with D-T and D-D reactors from the safety
point of view. Therefore, the D-3He reactor is expected
to be used as fusion energy source in the future.
In this study, we have investigated plasma physicsand engineering condition on the D-3He tokamak
reactor. In addition, considering with secondary D-D
reaction and tertiary D-T reaction, we estimate theneutron production, wall loading and the tritium fuelcycle in the reactor for the evaluation of safety.
2. Reactor design model and design constraints
The D-3He reactor design has been analyzed withthe conceptual design code (DRIVER) [1] which was
modified to calculate the D-3He reaction. Input
parameters are listed in Table 1. In this study, wechoose 5 MeV NBI because of high current drive
efficiency at 50 keV plasma. The overall efficiency forcurrent-drive system is assumed to be 80% assumingthat the RFQ and the laser photo detachment
neutralizer are used [2]. The parameters such as ne/nGW,
βN, HHy2, Pf are converged in self-consistent values.
The value of q95 and q0 are constrained to be more than
3.0, 1.0, respectively. Pe,net and Pw are also restricted sothat Pe,net≧1.0 GW, Pw≦1.0 MW/m2, respectively.
All the tritium particles generated by the D-D
reaction are reused as fuel in this reactor to minimize
stored tritium. In line with this principle, the density ofT in the plasma must be controlled to keep equality
between the rates of its consumption and production asfollows;
1 2(1)n D v
 nD nT v.
2D  D  p ,T 

[3]
[4]
[5]

UCLA-PPG-1384.
Y.R.Lin-Liu, R.D.Stambaugh, Nucl. Fusion 44 (2004) 548
K.Tobita, S.Nishio, M.Sato, et al., Nucl. Fusion 47 (2007)
892.
H.Shimotohno, et al., Fusion Eng. Design 69 (2003) 675.

Table 1. Input parameters
Elongation κ95/Triangularity δ95
NBI energy Eb (MeV)
Effective charge Zeff
Effective reflection coefficient of wall Rsyn
Thermal conversion efficiency ηTD (%)
Current drive system efficiency ηCD (%)

2.0/0.35
51.76
0.95
4580

Fig.1. Variation of normalized beta versus aspect ratio for R
from 6 to 12.

D T

3. Results
Figures 1 and 2 show the dependence of βN andne/nGW on A for R from 6 to 12. In Fig. 1, we plot βN
limit value as a function of A and κ induced by Lin-Liu
et al [3] and some reactor βN values [2, 4, 5].
Table 2 is a list of the reference design parameterswhich are indicated as ‘design point’ in Fig. 1 and Fig.
2, respectively. By Eq. (1), the ratio of tritium to fuelnT/nf is determined 0.0033 in this point.
References[1] K.Okano, Y.Ogawa and H.Naitou, Plasma Phys. Control
Fusion 32, 225 (1990).
[2] F.Najmabaji, R.W.Conn, et al., UCLA report

Fig.2. Variation of ne/nGW versus aspect ratio for R from 6 to12.
Table 2. Reference design parameters
R/a (m)ΑTe/Ti (keV)
ne/nf (1020m-3)
n3He/nD
nT/nf
ne/nGWBT (T)βN/βt10/4.17
2.4
46/50
1.25/0.79
10.0033
1.14
7.2
5.28/0.11

Ip (MA)fBS
q95/q0
HHy2
Pf/Pcon (MW)Pbr/Psyn (MW)Pe,net (MW)Pw,n (MW/m2)
Pw/Pw,div (MW/m2)

60
0.86
3.79/2.1
1.882900/778
942/1080
1150
0.082
0.82/30.9