Tokamak reactor

Table 2a. Plasma parameters and power balance for a beam-driven D-T tokamak and an ignited tokamak reactor...

The plasma parameters and power balance for a beam driven D-T Tokamak and an ignited Tokamak reactor are listed in Table 2 a for illustrative purposes. The ranges of photon and particles fluxes to be expected on the first wall are listed in Table 2b. 

Most of the sputtering data are for pure materials. In fact, most investigators have attempted to avoid surface contamination in order to make measurements truly representative of the substrate material. In a Tokamak reactor the wall will be sputter cleaned and hence these data are relevant. The actual conditions in today s operating Tokamaks are more complex. For example, carbon and other materials layers have been shown to build up on the surface of walls, and hence it is desirable to have sputtering data on samples with impurity layers195. ... 

W.L. Hsu, Glow-discharge removal of codeposited carbon films in graphite-lined tokamak reactors, J. Vac. Sci. Technol. A7 (1989) 1047... 

The characteristic circular-shape of the tokamak reactor is clearly seen here. The reactor uses strong magnetic fields to contain the intensely hot fusion reaction and keep it from direct contact with the interior reactor walls. 

Why does nuclear fusion require so much heat How is heat contained within a tokamak reactor (25.4)... 

F, Najmabadi, R.W. Conn and The Aries Team, The ARIESIl and ARIES-IV Second-stability Tokamak Reactors, TMTFE-IO, La Grange Park, IL, USA, 1992. 

Current tokamak reactor designs (CCTR Mkll B, STARFIRE) have parameters in the range B = 4-5 T, a = approx. 2 m, P = 4-5 MW m", toroidal 3 = 7%-9%, station size = 3.5-4 GW. In my talk on Tuesday I argued that the scale of these reactors indicated a specific cost ( /kW) substantially higher than that for a comparable fission power station, perhaps by a factor of between 3 and 5. 

In view of their own power requirements tokamak reactors have to be operated quasi-steady state with long burn times. Otherwise the mean energy gain would be too small and the circulating power of the system... 

Resume TECHNICALLY CREDIBLE IDEAS FOR IMPURITY CONTROL, WALL PROTECTION, ALPHA PARTICLE ENERGY REMOVAL AND EXHAUST IN COMMERCIAL TOKAMAK REACTORS ARE NOT AVAILABLE. 

The superconducting magnet system would probably be the most expensive part of a tokamak reactor. The typical target data for developing the toroidal magnet are shown in Fig. 3. 

Resume TOROIDAL MAGNETS FOR TOKAMAK REACTORS ARE FEASIBLE. 

Resume IGNITION IN TOKAMAK WILL PROBABLY BE POSSIBLE BY NEUTRAL INJECTION HEATING BUT NI IS PROBABLY NO WAY FOR REACTOR HEATING. RADIO FREQUENCY RF) HEATING IS TECHNICALLY MORE PROMISING. A SATISFACTORY SOLUTION FOR COMMERCIAL TOKAMAK REACTOR HEATING CANNOT YET BE SAFELY PREDICTED. 

If the net electric power density pei of the tokamak reactor is defined as the quotient of the plant net electric power Pei and the volume Ve which... 

Figure 9 also gives the neutron wall loadings pw and for NUWMAK the value of the power per unit weight p i of the nuclear islands. The reference value taken for the power density is that prevailing in the pressure vessel of pressurized water reactors (PWR). The structure of a PWR is less complex than that of a DT tokamak reactor would be and the materials required for its construction will, with all probability, entail lower specific energy costs than tokamak materials. In addition, the reference volumes chosen here for the tokamak reactors do not include essential subsystems of the nuclear island (e.g., start-up heating, fuel injection, selective vacuum pumps) because too little is as yet known about these. Power density comparisons made on this basis should therefore hardly lead to a pessimistic assessment of the economic chances of the tokamak as a power reactor principle. 

Resume IT CAN BE DRAWN FROM RECENT REACTOR DESIGN STUDIES, THAT THE MEAN VOLUMETRIC NET ELECTRIC POWER DENSITY IN TOKAMAK REACTORS WOULD ONLY BE 2.5 to 4% OF THE VALUE COMMON TODAY IN LIGHT WATER REACTORS AND THAT A TOKAMAK REACTOR WOULD REQUIRE ABOUT 12 kg OF CONSTRUCTION MATERIAL PER kW j TO BE BUILT, OR A FACTOR OF 17 MORE THAN FOR THE LIGHT WATER REACTOR. 

If a linear relation between the volumetric power density and neutron wall load is assumed, extrapolation of the data from the two fusion reactor designs yields the curves shown in Fig. 10, where the dependence of the blanket volume on the power density is ignored (optimistic extrapolation ). Compacting the construction beyond a certain limit is achieved at the expense of complexity and availability. The upper compacting limit is characterized by the so-called most compact tokamak reactor (A = 3 r = b = 1.75 m), whose power refers to the sum of the net volumes of the plasma vessel and the outer system (b), which comprise the blanket,... 

From Fig. 10 it can be deduced that the power density of the PWR could only be attained in a tokamak reactor of NUWMAK-type design, if structural material is available, which permits a neutron wall loading of about 90 MWjm, For a lifetime of 7 years this corresponds to an integrated wall loading of 630 MWyrjtn, ... 

The case is now considered where material with properties required to withstand these extraordinarily high wall loadings is available. The minimum mean -values then required for power density breakeven and the lower limit of the tokamak reactor powder can be taken from Fig. 12. 

Resume THE p-VALUES REQUIRED FOR COMPETITIVE TOKAMAK POWER DENSITIES VERY LIKELY CANNOT BE ACHIEVED IN TOKAMAKS. IF ALL POWER DENSITY CONSTRAINTS WERE DISPENSED WITH, THE MINIMUM TOKAMAK REACTOR POWER WOULD BE TOO LARGE, REGARDING NETWORK COMPATIBILITY. 

X — reflects the ratio of average specific material energy cost of the tokamak reactor as compared to those of PWR (x 1), unity has been chosen in the following as a conservative assumption. 

The power density to be achieved when applying present-day material (stainless steel ) would be, under most optimistic assumptions, more than one order of magnitude too low That means, the very complex tokamak reactor would require to be built of more than ten times larger a quantity of material of much higher quality than PWR of the same net eletric output. 

A tokamak reactor would need additional auxiliary power mainly... 

The mean volumetric net eletric power density in nuclear islands of recent conceptual tokamak power plant designs would be 2.5 to 4% of the value common today in the less complex structures of light water reactor nuclear islands (Fig. 14). Such tokamak reactors would require about 2 kg of construction material per kWei to be built or a factor of 17 more than for the PWR. 

Baker C. C. et ah, STARFIRE - Commercial Tokamak Reactor, in Proc. of 8 Symp, on Engineering Problems of Fusion Research, San Francisco 1979... 

Badger B. et ah, NUWMAK - a Tokamak Reactor Design Study, UWFDM-330, Madison, March 1979... 

For example. International Tokamak Reactor Zero Phase IAEA Vienna, 1980... 

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