24P107-P
Development of a systems analysis code for fusion DEMO reactor design
核融合原型炉設計に向けたシステムコードの開発	 
Makoto Nakamuraa, Hiroyasu Utoha, Kenji Tobitaa and Kiyotaka Hamamatsub
中村	  誠a, 宇藤裕康a, 飛田健次a, 濱松清隆ba

Japan Atomic Energy Agency, 2-166 Oaza-Obuchi-Aza-Omotedate, Rokkasho, Kamikita, Aomori 039-3212bJapan Atomic Energy Agency, 801-1 Mukoyama, Naka, Ibaraki 311-0193
a
日本原子力研究開発機構 〒039-3212	  青森県上北郡六ヶ所村大字尾駮字表舘2-166b
日本原子力研究開発機構 〒311-0193	  茨城県那珂市向山801-1

We report recent efforts towards improvement of a systems analysis code TPC for DEMO reactor design.
As a first step of such improvement, the calculated results from the two systems codes, TPC andPROCESS, are compared. The main result is that most of the calculation outputs from the two codes are ingood agreement while the radiation power losses calculated are somewhat different between the two codes
because of difference in the impurity radiation and spatial profile models. Some issues fordevelopment/improvement of systems codes relevant to DEMO plasma physics are discussed.

1. Introduction
For fusion research directed at electricitygeneration in the ITER and post-ITER era, it isnecessary to define development targets toward
DEMO including plasma parameters andengineering requirements such as magnetic fieldand divertor heat flux. These parameters andrequirements are strongly dependent on designconcepts such as whether the operation is steadystate or pulsed, the target net electric power,
assumed advancement in physics parameters andso on. Moreover, such parameters andrequirements are determined self-consistently. In
general as a first step of systematic reactor design,
systems analysis is performed in order to estimatereactor operation windows with engineering
constraints (e.g. [1]). More detailed physics andengineering analyses are performed as following
steps.
Systems analysis codes consists of a large
number of algebraic formulae representing plasma
physics phenomena and fusion engineering
components. Most of these formulae are coupledwith each other. Although many systems analysis
codes have been developed and applied to ITER
and commercial fusion reactor designs so far,there are some issues for fusion DEMO reactor
design.
1) Benchmarking existing systems codes andcomparison of the calculation results from thecodes are lacked. Some physics andengineering models, approximations andsolution methods are different among existing
systems codes, so that there are often
disagreement in calculation results from thesecodes and it is difficult to find root causes ofsuch disagreement because systems analysis
codes consists of a large number of algebraic
formulae.
2) It is still unclear weather existing physics
models used in the existing systems codes canbe applicable to a fusion reactor since most ofphysics models in the systems codes are basedon ITER Physics Guidelines [2].
Purposes of our work are to establish physics
and engineering basis on DEMO design and todevelop (or improve) a DEMO systems analysis
code. For these purposes it is important to resolve
the above issues.
2. Benchmark of the systems codes
The systems code TPC is being improved inJapan Atomic Energy Agency (JAEA) [3]. This
code was used for analysis of ITER operation
points [4]. To resolve the former issue described inSection 1, we compared calculation results from thetwo systems codes, TPC and PROCESS [5].
PROCESS is being developed in Culham Centre forFusion Energy (CCFE) and was benchmarked
against ITER-TAC costs. Comparison showed good
agreement in general [6]. In this presentation wefocus on comparison of the calculation results fromthe modules relevant to plasma physics in TPC andPROCESS. Comparison of the modules of fusion
engineering and cost evaluation will be reported
elsewhere.
The plasma physics calculation modules consistof two balance equations: the plasma power andcurrent balance equations. Each term in the balance
equations is evaluated based on the ITER Physics
Design Guidelines [2]. In the benchmark reported
here we used Nevins formula [7] for the bootstrap

current fraction. The fitting formula proposed by
Bosch and Hale [8] was used for the D-T fusion
reaction rate parameter <σv>DT. The ITER
IPB98(y,2) scaling [9] was used for the global
energy confinement time. The plasma temperatureand density profiles were assumed to be in aparabolic form characterized by the shaping factors
αT and αn, respectively.
The benchmark model parameters aresummarized in Table 1. While the plasma geometryis the same as ITER, the target fusion power is ofthe order of gigawatt, which is higher than in ITER.
The calculation results from PROCESS and TPC
are summarized in Table 2. Outputs from thecomputation modules relevant to plasma physics inthe two systems codes are in good agreement,
except for radiation power losses [10].
A possible cause of difference in the calculated
Pbrem and Plin values is difference in the impurity
radiation and spatial profile models. The models
used in TPC and PROCESS is summarized in Table
3. In the present benchmark calculation case,fortunately, the calculated values of the HH factor
from the two codes are in good agreement, asshown in Table 2. Thus, the difference in thecalculated impurity radiation power losses is not solarge to crucially affect the plasma power balance.
However, it would become large in a fusion reactor
in which impurities are actively seeded to reduce
divertor heat load, e.g. the DEMO reactor SlimCS[11].

[4] Y. Murakami, et al.: J. Plasma Fusion Res., 77(2001) 712.
[5] P.J. Knight:
F/MI/PJK/PROCESS/DOCUMENTATION/MANU
AL, United Kingdom Atomic Energy Authority(July 1996).
[6] T.C. Hender, P.J. Knight and I. Cook: Fusion
Technol., 30 (1996) 1605.
[7] W. M. Nevins et al: ITER-TN-PH-8-4, June 1988,Garching, FRG (1988).
[8] H.-S. Bosch and G.M. Hale: Nucl. Fusion, 32 (1992)
611.
[9] ITER Physics Basis: Nucl. Fusion, 39 (1999) 2175.
[10] M. Nakamura et al.: submitted to Fusion Eng. Des.
(2011).
[11] K. Tobita et al.: Nucl. Fusion 49 (2009) 075029.
Table 1 Input plasma parameters in the benchmark
calculation.

Table 2 Output calculation results from TPC andPROCESS.

3. Further works
In the presentation comparison of the calculation
results from the two codes will be discussed more
extensively. We will also discuss about the second
issue described in Section 1; we will examine
applicability of calculation models for somephysical phenomena, e.g. the synchrotron radiation,
impurity radiation and bootstrap current, to DEMO
design.
Acknowledgments
We thank Drs. Richard Kemp, David Ward,
Ryoji Hiwatari and Haruhiko Takase for fruitful
discussion on benchmark of the systems analysis
codes.
References[1] R. Hiwatari, et al.: Nucl. Fusion, 44 (2004) 106.
[2] N.A. Uckan and ITER Physics Group: ITER
Documentation Series, No. 10, IAEA/ITER/DS/10(1989).
[3] H. Fujieda, Y. Murakami and M. Sugihara:
JAERI-M 92-178 (1992) (in Japanese).

Table 3 Summary of the Pbrem and Plin models.