No abstract available

[en] A viable poloidal divertor concept has been developed for TNS which allows for the use of solid metal collectors and makes most economical use of the space inside the TF coils. The divertor can be implemented in the system without major impact on the overall size and cost. (author)

[en] Studies are being carried out at General Atomic Company and Oak Ridge National Laboratory to develop conceptual designs of tokamak fusion reactors for the TNS (The Next Step) programme. The primary purpose of these studies is to identify technical problems and to develop solutions to them. The TNS studies, initiated in 1976 under the sponsorship of the US Energy Research and Development Administration, have been directed to the development of designs of reactors which achieve ignition and plasma burns sufficiently long to study burn dynamics. The ORNL study has resulted in the design of a reactor with a D-shaped plasma which has a major radius of 5.0 m, a minor radius of 1.2 m, and a plasma elongation of 1.6. A toroidal β of 5% is achieved by adopting a flux-conserving mode of operation. The General Atomic design is based on the use of a Doublet plasma cross-section to achieve high β. This reactor design has a major radius of 3.6 m, a minor radius of 0.95 m, and a plasma height-to-width ratio of 2.7. Both designs have a plasma volume of approximately 225 m³ and a peak power in the 700-1000 MW(th) range. The current ORNL TNS reactor is designed for a plasma burn of 16 seconds, and the GA reactor is designed for a burn of 30 seconds. While the ORNL reactor is designed for a comparatively modest duty factor of 0.05, the GA reactor is designed for a duty factor of 0.5 and includes a blanket and power conversion system to produce a nominal amount of electric power. The costs of the current TNS reactors are estimated to be in the range of US $400 - US $600 million without escalation and specific supporting research and development. (author)

[en] Studies at the Oak Ridge National Laboratory (ORNL) and the General Atomic Company (GA) have defined basic characteristics and requirements for The Next Step (TNS) in the U.S. Tokamak Development Program. The Reference Design concepts include engineering innovations that have enhanced the feasibility of the tokamak as a power reactor. A major emphasis has been placed on configuration changes to improve access for maintainability, a serious concern and frequent criticism of previous studies. In addition, system designs have been incorporated using existing or modest extensions of engineering technology. (orig.)

[en] In this fourth part of the four-part TNS Draft Program Plan, project engineering concerns are considered. The TNS Project is first broken down into the major time and functional periods of feasibility study, preconceptual design, conceptual design, and line item construction, while the elements of the project are organized into an administrative work breakdown structure. With the aid of these two classifying schemes, the project tasks are described in terms of schedule, estimated cost, type of funding, and proposed type of participant. The initial constraints of completion data, anticipated scientific inputs, and budget procedures are used to develop a two-phase project in which the facilities are authorized first and the device 2 years later. This specific mechanism is fundamental to the construction of the schedule and should be reconsidered when the completion and initiation dates are reformulated

[en] A status report on the Oak Ridge TNS Program has been prepared with three basic parts--a summary of the FY 1977 activities, a discussion of the current baseline design, and a statement of work tasks for FY 1978. Within the FY 1977 activities, the plasma engineering efforts were directed toward improving the economical performance of tokamak reactors and toward easing the requirements placed upon the supporting technology development programs. The FY 1977 systems modeling efforts were used to develop comprehensive systems models for cost comparison of different toroidal field (TF) coil technology options. The FY 1977 program planning tasks provided a draft program plan with both an R and D assessment and schedule considerations. On the basis of these activities, the FY 1978 effort is being directed toward initiation of preconceptual design. The current baseline design, characterized by key parameters and overall layout drawings, is being developed from the FY 1977 activities as a starting point for the FY 1978 preconceptual design study tasks. The projected performance of the baseline design as an ignited and burning primitive fusion reactor facility is being developed through self-consistent plasma engineering calculations using 0-D, 1-D, and 1-¹/₂-D models. A set of pertinent work tasks for the FY 1978 effort has been developed from a systematic analysis of the status of each subsystem

[en] The Next Step (TNS) represents the stage of fusion energy development in which the major emphasis is on engineering testing and demonstration. In this document, the activities of the Oak Ridge TNS Program for FY 1978 are described and summarized. The Reference Design that has evolved from these activities is described, its operating characteristics are examined, and project planning issues are considered. Major conclusions from the FY 1978 effort are stated

[en] A design is presented that suggests that a negative ion neutral beam based on direct extraction is applicable to TNS, assuming technological advancements in several areas. Improvements in negative ion sources, direct energy conversion of charged beams, and high speed cryogenic pumping are needed. The increase in efficiency over a positive ion system and the encouraging results of the first attempt at a total design justify increased effort in the development of the above mentioned areas

[en] This volume presents an overview of the design study effort, with attention both to the technical highlights and to the programmatic recommendations that have emerged

[en] This paper presents an approach to analyzing a toroidal plasma chamber for the prevention of both static and dynamic buckling. Results of stability analyses performed for the doublet shaped plasma chamber of the General Atomic 3.8 meter radius TNS ignition test reactor are presented. Load conditions are the static external atmospheric pressure load and the dynamic plasma disruption pulse load. Methods for analysis of plasma chamber structures are presented for both types of load. Analysis for static buckling is based on idealizing the plasma chamber into standard structural shapes and applying classical cylinder and circular torus buckling equations. Results are verified using the Buckling of Shells of Revolution (BOSOR4) finite difference computer code. Analysis for the dynamic loading is based on a pulse buckling analysis method for circular cylinders