Steam generator for BN-800 reactor NPP
Its structure is based on section-modular concept, which allows to keep SG in operation even in case of heat-exchanging surface depressurization of one of the modules of any section.
The SG consists of 10 sections, each having one straight-tube module of evaporator and superheater, binding pipelines with necessary valves. The BN-800 SG is a further upgrading of the BN-600 plant SG, which has been successfully operated in power mode since April 1980.
SG is intended for generation of superheated steam as a part of power unit of a three-loop BN-800 plant with fast neutron reactor and sodium coolant in the primary and secondary circuits.
SG structure and fastening provide:
- normal continuous operation under OBE of magnitude 6 according to MSK 64 scale;
- normal operation of the secondary side under SSE of magnitude 7 according to MSK 64 scale, plant cooldown under all modes except for the cases of loss of feedwater supply in modes “water-stop”, “loss of power”;
- keeping SG in operation under the condition of “small leak” of water into sodium by quick automatic disconnection of the section containing the failed module;
- protection of the secondary equipment against overpressure under the condition of “large leak” and bringing SG out of operation with discharge of products of water-sodium interaction into the emergency protection system tanks;
- integrity of module body, secondary equipment and pipelines under pressure increase in them in case of instantaneous guillotine break of one heat-exchanging tube.
SG structure provides:
- easy access for examination, repair and replacement of the internals on the third side;
- replacement of the failed module with a new one;
- performance of non-destructive test of binding pipeline connections and pipe-to-module welds;
- withdrawal of heat exchanging tubes for laboratory studies.
|Thermal power, MW||700|
|Steam capacity, t/h||1050|
|Secondary coolant temperature, °С|
|Secondary coolant flow rate, t/h||10 100|
|Feed water temperature, °С||160-210|
|Live steam temperature, °С||495|
|Pressure differential on the SG secondary side path, MPa||0,14|
|Pressure differential on the SG steam-water path, MPa||1,24|
|Pressure downstream the steam superheater, MPa||13,7|
|SG mass, kg|
|- dry||1 053 000|
|- in operating condition||12 175 000|