28pB10
パルス運転型および定常運転型トカマク炉における比較研究
A Comparison of Pulsed and Steady-State Operation Tokamak
濱田 敏弘1, 岡野 邦彦1
Toshihiro HAMADA1, Kunihiko OKANO1
1

東京大学 新領域創成科学研究科
1
Frontier Sciencies,University of Tokyo
We are comparing cost in order to clarify possibility of pulsed andstainless steel at 4K[5]. Also we adopted paris’ law, that is the moststeady-state operation tokamak because the both of those are

popular fatigue crack growth model, for JJ1 at 4K[6]. We scanned

being studied as a realistic tokamak demo reactor. We havecycles to failure at Sm/1.5, Sm/3, Sm/5 of stress amplitude, andevaluated cost of the both reactor using FUSAC[1] system code. We

Rp=10m, 11m, 12m of reactor size, where Sm is design stressdefined a normalized cost point as an unit for this evaluation instead

intensity, which of JJ1 at 4K is equal to 800MPa. This result is plottedof particular currency. 100 cost point is defined to equivalent direct

on Figure 2. As a result, it is derived that CS fatigue is not socost of ITER[2] and correspond generating system totally. Structure

dominant but constraint of current density is more dominant. Theof the evaluated cost is shown in Figure 1. We choose acurrent constraint do not let CS coil be thin.

representative of pulsed tokamak which has Rp=10m and ananother representative of steady-state which has Rp=7.25m, that is

And now TF coil fatigue evaluation is undertaken.
250

Their utility powers are set to be about 600MWe. We have added
new calculation for cost of the NBI device to be inversely
proportional to beam energy of MeV. Because the cost must be
directly proportional to rather beam current, which is ∝(1/acceleration voltage) ∝ (1/beam energy), than power. In orderaround 60MWe with an efficiency multiplier. 2GWthh of thermal

Indirect CostTritium Initial Loading
Small fusion power=> small BOP

Thermal Transportation System
Divertor Plate

50Normalizing
Tokamak(ITER +GeneratingSystem)other and led to almost same cost of between steady-state andpulsed tokamak. We are now modifying PF coil calculation module
because of its much lower cost than TF cost. Fatigue, that is one ofmajor issues in pulsed tokamak, has not be considered yet also.
So next we have scanned design window for fatigue stress of CS
coil of pulsed operation. We applied S-N curve extrapolated fromexperimental data and Morrow’s law for cryogenic JJ1 austenitic

PULSE

demo-CREST(op3)

Shields
Blanket System
Magnet Systems

Figure 1: Normalized capital costs of tokamaks
S-N curve for JJ1, 4K(derived from Morrow equation)

stress amplitude Δσ[MPa]Pf than those of steady-state reactor. Those effects canceled eachStructures

0based on 50～100$ per 1kWh unit[4]. So it is equivalent 2 points ofand BOP don’t cost so high because of comparably lower Btmax andNB Heating

mild field intensity=> small Magnet

time. Its direct construction cost is estimated 100-200M$, which isshield cost high because of its large body. On the other hand, coil

BOP

100

tokamak so as to supply utility and plant circulating power in dwell

almost equally. In case of pulsed tokamak, blanket, structures andHousing & Attaching Facilities

150

direct costof ITER+BOP=>100point

storage by molten salt is assumed to be installed only for pulsednormalized cost. As the result, both reactors are clarified to cost

Construction Interest200

to apply FUSAC to not only steady-state but pulsed tokamak design,
also we have arranged code for the NBI power calculation to be

Energy Storage

Energy storage costis only 2 point

equivalent to demo-CREST[3], where Rp is plasma major radius.

1300
Nf/20
1200
1100
Δσ/2
1000
900
Sm=800MPa
12m 11m 10m
design S-N
800
700
600
Sm/1.5 =533MPa
mandatory
desireble
500
area
area
400
Sm/3 =267MPa
300
initial clack=1mm
Sm/5 =160MPa
area that satisfy design S-N
2005mmand both curves of 1mm
100
and 5mm clack
1.0E+02
1.0E+03
1.0E+04
1.0E+05
1.0E+06cycle to failure Nf [times]

Figure 2: Scan for fatigue life various reactor size
[1] T. Yoshida et al.,Development of Assessment Code of Fusion Power Reactors, Research
Report T94001, CRIEPI (1994)[2] Y. Shimomura et al., Nucl. Fusion 41, 309 (2001).
[3] K.Okano et al., J. Plasma Fusion Res. 80 241 (2004)[4] http://www.scientificamerican.com/article.cfm?id=how-to-use-solar-energy-at-night[5] K. Hamada et al. / Fusion Engineering and Design 75–79 (2005) 87–91[6] T.N.Todd et al. / CCFE-R(12)17 THE KEY IMPACTS OF PULSED OPERATION ON THE
ENGINEERING OF DEMO pp.48