Reactor pressure vessel design of the high temperature engineering test reactor

The reactor pressure vessel (R-PV) of the HTTR is 5.5 m (inside diameter), 13.2 m (inside height), and 122 mm (shell thickness). The RPV contains core components, reactor internals, reactivity control system, etc. 2 1/4Cr-1Mo steel is chosen as the material for RPV. The temperature reaches about 400degreesC at normal operation. The fluence of the RPV is estimated to be less than I x 10(17) n/cm(2) (E > 1 MeV) and so irradiation embrittlement is negligible, but temper embrittlement is not negligible. For the purpose of reducing embrittlement, content of some elements must be limited in the 2 1/4Cr-1Mo steel for the RPV; embrittlement parameters, J-factor and X are used. In this paper, design and structure of the RPV are reviewed first. Fabrication procedure of the RPV and its special feature are described. Material data on the 2 1/4Cr-1Mo steel manufactured for the R-PV, especially the embrittlement parameters, J-factor and 9, and nil-ductility transition temperatures, T-NDT, by drop weight tests, are shown. In-service inspection and results of R&Ds are also described. (C) 2004 Elsevier B.V. All rights reserved.