Fusion Engineering and Design 86 (2011) 1971–1974 Contents lists available at ScienceDirect Fusion Engineering and Design journal homepage: www.elsevier.com/locate/fusengdes Thermo-hydraulic design verification of the neutral beam liner for the ITER vacuum vessel Jin-Ki Ham a,∗ , Young-Ki Kim a , Dong-Hae Kim a , Jeong-Woo Sa b , Byung-Chul Kim b , Hee-Jae Ahn b a Electro-Mechanical Research Institute, Hyundai Heavy Industries Co. Ltd., 102-18 Mabuk-dong, Giheung-gu, Yongin-si, Gyeonggi-do 446-716, South Korea b National Fusion Research Institute, 113 Gwahangno, Yuseong-gu, Daejeon-si 305-333, South Korea article info Article history: Available online 20 January 2011 Keywords: International thermonuclear experimental reactor (ITER) Neutral beam (NB) port NB liner Heat transfer Pressure drop abstract The ITER vacuum vessel has upper, equatorial and lower port structures used for equipment installation, utility feedthroughs, vacuum pumping and access inside the vessel for maintenance. A neutral beam (NB) port of equatorial ports provides a path of neutral beam for plasma heating and current drive. An internal duct liner is built in the NB ports, and copper alloy panels are placed in the top and bottom of the liner to protect duct surface from high-power heat loads. Global NB liner models for the upper panel and the lower panel have been developed, and flow field and conjugate heat transfer analyses have been performed to find out pressure drop and heat transfer characteristics of the liner. Heat loads such as NB power, volumetric heating and surface heat flux are applied in the analyses for beam steering and misalignment conditions. For the upper panel, it is found that unbalanced flow distribution occurs in each flow path, and this causes poor heat transfer performance as well. In order to improve flow distribution and to reduce pressure losses, hydraulic analyses for modified cooling path schemes have been carried out, and design recommendations are made based on the analysis results. For the lower panel, local flow distributions and pressure drop values at each header and branch of the tube are obtained by applying design coolant flow rate. Together with the coolant flow field, temperature and heat transfer coefficient distributions are also acquired from the analyses. Based on the analysis results, it is concluded that the lower panel for the NB liner is relatively well designed even though the given heat loads are very severe. © 2010 Elsevier B.V. All rights reserved. 1. Introduction The primary functions of the vacuum vessel (VV) are to pro- vide a high quality vacuum for the plasma and to play a role of the first confinement barrier of radioactive materials [1]. The decay heat of all the in-vessel components can be removed by cooling water in the VV primary heat transfer system. The VV has upper, equatorial and lower ports used for equipment installation, util- ity feedthroughs, vacuum pumping and access inside the vessel for maintenance. The neutral beam (NB) ports located side by side at two equatorial ports provide a path of NB for plasma heating and current drive [2]. An internal duct, namely NB liner is inserted in the port structure as shown in Fig. 1(a). The main functions of the liner are to protect the VV wall from the high-power neutral beam, to give radiation shielding of the TF coil and to provide a compo- nent with high cooling performance [3]. Particularly the neutral beam makes a large heat influx on top and bottom wall of the liner. In order to dissipate the heat load efficiently, copper panels and coolant tubes are installed at top and bottom wall of the liner. ∗ Corresponding author. E-mail addresses: hjinki@hhi.co.kr, hjinki@empal.com (J.-K. Ham). Heat loads caused by NB are classified as surface heat flux due to plasma radiation, volumetric heating generated by neutron and gamma ray and NB power density. Khripunov [4] calculated a total nuclear heating power using an improved three-dimensional VV model. It is about 11 MW including nuclear power released in the NB liner. Sato et al. [5] evaluated the detailed distributions of the nuclear heating rate and surface heat flux of the NB liner using three-dimensional Monte Carlo neutron and gamma ray transport code, MCNP-4C. They established analytical expressions of these nuclear responses by fitting the obtained data as a function of the distance from the first wall surface. Recently higher NB power density is proposed due to severe heat flux caused by a beam steering and a vertical misalignment so that separate cooling of upper and lower panels of the liner is strongly recommended. During preliminary design activities, a number of critical issues such as sufficient cooling performance and remote handling became apparent, and consequent basic NB liner model is determined as shown in Fig. 1(b). United Kingdom Atomic Energy Authority (UKAEA) carried out thermo-hydraulic analyses of the lower panel of the NB liner by using PlantFlow Software [6,7]. They suggested that required flowrate for cooling panels be 18.6 kg/s and calculated pressure drop between inlet and outlet of the panel be about 10 bar. How- 0920-3796/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.fusengdes.2010.12.043