At the chosen parameters the gross thermodynamic efficiency for V-500 SKDI equals 38.1% and the net efficiency equals 37.0%. The absence of main circulation pumps (MCP) reduces the auxiliary power requirement. The main equipment masses for VVER-1000 and V-500 SKDI are presented in Table 3.

V-500 SKDI capital costs relative to those of VVER-1000 will decrease by the reduction of the necessary expensive equipment (absence of primary piping, MCP, accumulators and outside SG). The use of spectral reactivity control gives the possibility of improving the fuel cycle in comparison with that in current LWRs. According to estimations the natural uranium requirements in V-500 SKDI will be 1.1 times less than in VVER-1000. The reduction of the number of equipment units and the plant layout simplification will lead to a decrease of concrete specific expenditures and construction costs. The proposed safety systems and the guard vessel prevent steam and fission products from being released into the containment volume. Consequently the main goal of the V-500 SKDI containment is the defense of the plant against external effects. This simplifies the containment design as compared with an LWR containment. Accordingly in estimates made for beyond design basis accidents the values of population exposure dose limits are not exceeded at a distance of 500-600 m from the NPP. This permits us to consider the opportunity of an NPP location close to large cities and its use for nuclear co-generation.

The factors enumerated above should lead to the improvement of V-500 SKDI technical and economical characteristics as compared with those of current middle and large sized nuclear power plants.

Alongside with development of the V-500 reactor design possible other ways of using water of supercritical pressure in nuclear power were considered. It seems promising to develop integral plants of small power for which the problems of reactor vessel manufacturing are simplified with the acceptable decrease in costs. For example, for a reactor of 250 MW (el) power the vessel OD is 3,5 m with the wall thickness being 240 mm.

From the ecological point of view it seems interesting to use the economically justified possibility, in the case of development of reactors with water of supercritical pressure, of the application of dry and wet water cooling towers to remove heat from the condensers. It will be especially important in the case of using reactors with water of supercritical pressure a for nuclear power-and-heating plants and its location in the vicinity of towns. With the thermodynamic efficiency of the cycle being of the order of 38% the specific amount of steam coming to the turbine is approximately 25% less than this value for WWER-1000. During operation of NPPs with reactors using water of supercritical pressure under the conditions of nuclear power-and-heating plant the steam flow rate into the condenser will reduce by 20% more.

6. Conclusion

Integral NPP with an electrical capacity of 500MW with natural circulating coolant may be created in a vessel with a diameter of less than 5 m with the use to a supercritical primary pressure. The V-500 SKDI safety level satisfies the requirements of the new generation to NPPs. The V-500 SKDI economic characteristics are not inferior to those of current NPPs due to the reduction of capital costs, improved fuel cycle characteristics, plant layout simplification and simpler operation. The NPP may be created on the existing Russian industry base without any significant change of modern LWR technology. It is necessary to construct a V-500 SKDI prototype reactor for testing of the accepted design and to make new decisions. The possible ways of using water of supercritical pressure in nuclear power have been considered.

REFERENCES

[1] Objectives for the development of advanced nuclear plants. JAEA, 1993.

[2] V. S.Protopopov, Teplofysica wisoky temperatur 4 (1977) 815-821.

[3] V. S.Protopopov and V. A.Silin, Teplofysica wisoky temperatur 2 (1973) 445­447.

[4] V. A.Silin, V. A.Voznesensky and A. M.Afrov, Nuclear Engineering and Design 144 (1993) 327-336.