XII. Operations Plan

Abstract

The operating program for BPX after the achievement of first plasma may conveniently be divided into a preliminary phase and a burn physics phase, the latter forming the major focus of the project. The preliminary phase includes the development tasks and physics studies necessary to reach the high-Q plasma regime. In this section, we describe the operational plan for the preliminary phase and the early part of the burn physics phase. In developing this plan, we have aimed at achieving high-Q D-T operation within 3 years from the first plasma operation. To meet this target, it has been necessary to assume that the physics predictions that underly the BPX design will be largely fulfilled during the preliminary phase, so that extensive investigation of fundamental physics issues in the nonignited regime will not be necessary. It must also be pointed out that since some details of the BPX design remain to be determined on the basis of future results from existing and planned experiments [e.g., the provision of electron cyclotron heating (ECH) as well as ion cyclotron resonance frequency (ICRF) auxiliary heating], details of this plan will continue to evolve. The operation of BPX is subject to several significant constraints, some of which have not been encountered in planning for previous tokamak experiments. The most obvious is the radiation associated with D-T operation and the resulting activation of the structure. The activation levels after a single ignited discharge are sufficiently high to prohibit personnel access inside the central cell surrounding the machine and to restrict all maintenance inside this area to remote-handling techniques. Even operation with deuterium plasmas at high auxiliary heating power results in significant activation levels: running 1000 deuterium plasmas with stored energies of 5 MJ over a 7-month period produces a dose rate of 6 rem/h at the vacuum vessel after a week of cooling down. Thus, the restrictions on access to and maintenance capability for an activated system have substantial bearing on the operations plan throughout the life of the experiment. The impact of the limited fatigue lifetime of the device must also be considered during all phases of this plan. The magnets are designed for a lifetime of 3000 full-field (B = 9 T, I = 11.8 MA) plasma shots (excluding commissioning shots), with an allowance for an additional 30 000 shots at half of