LIU KUKUI, LI MANCHANG, TANG CHUANBAO Nuclear Power Institute of China,

Chengdu, Sichuan Province,

China

Abstract

In China, heat supply consumes more than 70 percent of the primary energy resource, which makes for heavy traffic and transportation and produces a lot of polluting materials such as NOz, SOz and C02 because of use of the fossil fuel. The utilization of nuclear power into the heat and electricity co-generation plant contributes to the global environmental protection.

The basic concept of the nuclear system is an integral type reactor with three circuits. The primary circuit equipment is enclosed in and linked up directly with reactor vessel. The third circuit produces steam for heat and electricity supply. This paper presents basic requirements, reactor type choice, design characteristics, economy for a nuclear co-generation plant and its future application.

The choice of the main parameters and the main technological process is the key problem of the nuclear plant design. To make this paper clearer, take for example a double-reactor plant of 450 x 2MW thermal power. There are two sorts of main technological processes. One is a water-water-steam process. Another is water-steam-steam process. Compared the two sorts, the design which adopted the water-water-steam technological process has much more advantage. The system is simplified, the operation reliability is increased, the primary pressure reduces a lot, the temperature difference between the secondary and the third circuits becomes larger, so the size and capacity of the main components will be smaller, the scale and the cost of the building will be cut down.’ In this design, the secondary circuit pressure is the highest among that of the three circuits. So the primary circuit radioactivity can not leak into the third circuit in case of accidents.

keywords

small-sized nuclear co-generation, integral, self-pressurized, forced circulation, water-water-steam technological process

1 Introduction

With the development of human society, more and more heat supply is needed. The heat supply consumes more than 70 percent primary energy resource in China, while the electric power supply consumes only about 20 percent of the resource. It not only uses up about more than 4 x 10s tons coal every year, but also burns a great quantity of oil, which makes for heavy traffic and transportation , and causes environmental pollution and unnecessary resource waste. It is a good idea to construct a batch of nuclear co-generation plants near to the cities where the steam and heat supply is centralized in the future. This is a new way to save energy, relax traffic and transportation and reduce environment pollution.

The development of nuclear co-generation plant is a possile of prospective economical way, but how to ensure that the small-sized plant clean, safe and cheap is the first problem to be considered by the designers. Based on previous design experience, the plant design objectives are put forward as follows:

(1) Low basic capital investment The specific cost of the plant should be less than 750 $/KW;

(2) Construction period: A single-reactor plant needs about 5 years and a double-reactor plant needs about 6 years;

(3) Operational reliability: The availability is up to about 85%-90% and the load factor is more than 80%;

(4) No large pipe break accidents (all the plant pipe diameters are less than 100mm) and no LOCA in the primary circuit The reactor melt probability is less than 10’7/reactor-year. The reactor can be cooled using its own resources and the storage battery sources when normal onsite and offsite electric power is lost The plant can be built in a usely-populated area because of the reactor’s passive safety and high reliability;

(5) Being simplified in system, compacted in layout and of small constructive scale;

(6) Because the high and large reactor building is cancelled and the foundation loading is lightened, the plant can be built in seabeach, soft soil, seismic areas and so on. On the plant site choice, it is similar to the fossil-fueled power plant;

(7) The heated steam for heat supply has no radioactivity and its radiation level almost equals that of natural radiological reference state;

(8) The reactor building is pressurized and airtight The environment around the plant would not be polluted in case of radioactive leakage.