UA23401U - Method for passive heat protection of the thermal cover of the reactor compartment of a nuclear power station - Google Patents

Abstract

The proposed method for passive heat protection of the thermal cover of the reactor compartment of a nuclear power station consists in removing heat from the surface of the hot pipeline of the second circuit of the reactor through the annular gap between the heat insulation layer of the hot pipeline and the reinforced concrete wall. The protection of the reinforced concrete wall against overheating is provided by the passive transfer of latent heat of vaporization of the intermediate heat medium to ambient air. The heat flux from the outside surface of the hot pipeline is absorbed by the evaporator. The transfer of heat from the evaporator to ambient air is provided by the condenser. Movement of ambient air is provided due to natural draft outside of the thermal cover.

Description

Description of the invention

The useful model belongs to nuclear energy, specifically, to methods of thermal protection of reinforced concrete 2 structures of hermetic shells of reactor units of nuclear power plants (NPP). The invention can be used to develop a method of passive thermal protection of reinforced concrete walls of hermetic shells of reactor compartments of nuclear power plants from overheating in places where they are crossed by hot pipelines of the second circuit through hermetic ducts.

A known method of thermal protection against increased thermal load of reinforced concrete structures 70 of the thermal envelope of the reactor compartment in the places of passage of hot pipelines of steam, feed water and steam generator purging through hermetic ducts, which involves the forced circulation of air in the hermetic duct through the annular gap between the thermal insulation of the hot pipeline and reinforced concrete (Instructions for operation.

Localizing systems! security blocks Mo1, 2. MIZ. 1.0001.0029. - Ministry of Fuel and Energy

of Ukraine, SE "National atomic power generation company "Znergoatom", OP "Yuzhno - Ukrainskaya 12 dZS", Reactor shop Mo11.

According to the set of essential features, the method of cooling the technological hermetic ducts of hot steam pipelines located between the reactor compartment and the deaerator compartment of the steam turbine installation was chosen as a prototype (Instructions for operation. The ventilation system of the reactor compartment of the Mo1 unit.

IZ 1.0001.021. - Ministry of Fuel and Energy of Ukraine, State Enterprise "National Atomic Energy Generating Company "Znergoatom", OP "Yuzhno-Ukrainskaya AZS", Reactor shop Mo1) and (instructions for operation.

The ventilation system of the reactor compartment of the Mo2 unit. IZ 1.0001.019. - Ministry of Fuel and Energy

of Ukraine, SE "National atomic power generation company "Znergoatom", OP "Yuzhno - Ukrainskaya

Gas station", Reactor workshop Mo)

The permissible temperature inside the thermowell, which ensures maintenance of the specified strength characteristics of reinforced concrete, should not exceed 359C. Forced circulation of cooling air is carried out by constantly working exhaust ventilation. Moreover, three fans are used for cooling: one is constantly in operation and two are in reserve. The power supply of the cooling system is provided by the power supply system for the power unit's own needs. During a prolonged emergency power outage or disruption of the power supply of the cooling system, it is possible to overheat the embedded elements - hermetic ducts, which will cause cracking of the reinforced concrete wall of the shell of the reactor compartment with av! possible violation of its tightness.

The prototype has a number of significant shortcomings. The main one of them is that the forced supply of cooling air t requires constant power supply and in emergency modes of de-energization of self-demand sections of power unit "9" loses its efficiency. In addition, continuous operation of electric fans requires constant costs

From electricity, which increases the costs of the power unit for its own needs and reduces the efficiency of the nuclear power plant of the NPP.

The next disadvantage of the prototype is its low reliability. A large number of active elements are needed to organize the forced supply of cooling air: fans with electric drives and electric-driven fittings, which reduces its reliability. An increase in the reliability of the prototype is provided by three-fold Z7Z 70 redundancy of the cooling channels, which increases its construction cost, requires increased costs for maintenance and replacement of equipment that has exhausted its life. "z The prototype is implemented using equipment that has a large mass and dimensions and occupies a significant amount of space at the NPP power unit.

The essence of the useful model is the development of a method of passive thermal protection of reinforced concrete structures from overheating in the locations of hermetic ducts of the second circuit pipelines crossing the hermetic shell of the reactor compartment. o The solution of the task is provided by the organization of the removal of heat emissions from the hot pipeline due to the transfer of the latent heat of vaporization of the intermediate heat carrier of the two-phase thermosyphon (DTS), which ensures the removal of the heat flow from the hot pipeline to the final absorber ("in 50. atmospheric air. Heat removed from of the outer surface of the hot pipeline through a layer of thermal insulation, is spent on the vapor of the intermediate coolant DTS.

The essence of the useful model is explained by the drawing.

Figure 1 shows the sequence of removal of the heat flow from the hot pipeline to the final absorber by the claimed method. 99 In Fig. 2 - the direction of movement of the condensate of the intermediate coolant in the section of the thermosiphon evaporator, where 1 - the reinforced concrete wall of the reactor compartment shell; 2 - sealed steel cladding;

C - pipeline of the second circuit; 4 - external thermal insulation; 60 5 - DTS evaporator; 6 - heat flow from the hot pipeline; 7 - the direction of steam movement during the evaporation of the intermediate coolant in the DTS evaporator; 8 - direction of movement of steam from the evaporator to the DTS condenser; 9 - the direction of condensate movement in the DTS condenser; bo 10 - direction of movement of condensate in the wick membrane;

11 - capillary - porous wick; 12 - wick membrane; 13 - DTS capacitor; 14 - exhaust air ventilation channel; - cooling air.

The method of passive thermal protection against overheating of the reinforced concrete wall 1 of the shell of the reactor compartment in the place of its intersection with the hot pipeline From the second circuit through the hermetic pipe consists in the removal of heat emissions from the hot pipeline With the transfer of the latent heat of vaporization of the intermediate 7/0 coolant of the two-phase thermosyphon to the final absorber - cool air 15, which moves due to natural draft in duct 14 of exhaust air ventilation, located outside reinforced concrete wall 1.

The DTS is formed in the reinforced concrete wall 1 in such a way that its evaporator 5 is an intermediate element between the hot pipeline C and the reinforced concrete wall 1. The hot pipeline C of the second circuit with external thermal insulation 4 at the intersection of the hermetic steel lining 2 of the shell of the reactor compartment and 15 of the reinforced concrete wall 71 passes inside the evaporator 5 DTS. Condensers 13 of the DTS are placed outside the reinforced concrete wall 71 and placed in the exhaust air ventilation channel 14. The inner surface of the cylindrical walls of the evaporator 5 of the DTS is covered with a capillary-porous wick 11 with wick membranes 12.

The claimed method is implemented as follows. The process of evaporation of the intermediate heat carrier takes place in the evaporator 5 of the DTS due to the heat flow 6 coming from the hot pipeline C through the external thermal insulation 4, while the steam moves in the direction 7. Next, the steam of the intermediate heat carrier moves from the evaporator 5 to the condensers 13 in the direction 8. After this vapor of the intermediate coolant condenses during cooling of the condensers 13 from the outside by the cooling air 15 moving in the channel 14 of the exhaust air ventilation due to natural draft. Condensate of the intermediate coolant DTS due to mass forces flows from the condensers 13 to the evaporator 5 in the direction 9. The uniform supply of condensate in the direction 10 to the entire surface of the evaporator 5 of the DTS is ensured by the Tnot membranes 12 due to capillary forces.

The claimed method differs from the prototype in that it has a number of significant advantages. t

The main advantage of the proposed method is increased reliability with the possibility of providing thermal protection of the reinforced concrete wall in any operating conditions of the power unit, including emergency shutdown of the nuclear power plant with the loss of backup sources of electricity. Due to the absence of equipment with moving elements, such as fans with electric motors, fittings with electric drives, the reliability of the thermal protection of the reinforced concrete wall increases and the need to use backup channels of the cooling system is eliminated. at

The method of thermal protection is passive, it provides constant thermal protection of the reinforced concrete wall of the shell "E" of the reactor compartment without consuming electricity and does not require the intervention of personnel to control its operation. This increases the safety of the NPP in emergency situations with blackouts. During a complete loss of power supply for the NPP's own needs, thermal protection does not lose its functionality, it functions autonomously. with

Therefore, under emergency conditions, overheating of the reinforced concrete wall of the reactor compartment shell in the area of the hermetic duct with subsequent cracking of the reinforced concrete and possible depressurization of the hermetic steel lining will not occur. This will exclude the penetration of radioactive contamination outside the envelope of the reactor compartment and in a similar emergency situation will not lead to radiation pollution of the environment.

LES space. with с Efficiency of heat removal from the hot pipeline crossing the shell of the reactor compartment. through a hermetic pass, provide a high intensity of heat transfer processes in DTS with phase and transitions The intensity of heat transfer to the final absorber is achieved due to a relatively high (8...1Ω/s) speed of the cooling air.

The use of thermal protection based on DTS increases the economic efficiency of NPP operation. Absence

The GI of energy consumption for thermal protection of the reinforced concrete wall of the reactor compartment shell reduces the power unit's costs for its own needs, increases the efficiency of the nuclear power plant, and reduces the cost of electricity produced by the nuclear power plant. The method reduces costs for NPP repair and replacement of equipment with a limited service life, such as fans, fittings, electric drives.

The technical solution related to the use of the principle of operation of DTS, which is an autonomous heat transfer element of a closed type, for thermal protection of the reinforced concrete wall of the reactor compartment shell, is

It is significant, because the declared solution provides the appearance of new, different from the prototype properties: passivity, autonomy, increased safety, including ecological, reliability, efficiency and economy.

The autonomy and passivity of the proposed solution are significant differences, and the improvement of safety, reliability, efficiency and economy of the organization of thermal protection of hermetic pipes of hot pipelines allows to achieve a positive effect.

Claims (1)

The formula of the invention The method of passive thermal protection of hermetic shells of reactor compartments of nuclear power plants, based on the removal of heat emissions from the hot pipeline of the second circuit due to the circulation of air in the hermetic duct through the annular gap between the thermal insulation of the hot pipeline and the reinforced concrete wall, which is distinguished by the fact that thermal protection against overheating of the reinforced concrete wall is carried out by passive removal of heat emissions from the hot pipeline due to the transfer of the latent heat of vaporization of the intermediate heat carrier of the two-phase thermosyphon and ensure the removal of the heat flow to the final absorber - atmospheric air, while the evaporator of the two-phase thermosyphon perceives the heat flow from the external thermal insulation of the hot pipeline, and the heat is removed by the condenser to the final absorber, for which atmospheric air is used air, the movement of which occurs due to natural draft in the cooling channel, which is placed on the outside of the hermetic envelope. - «- «c) « (ze) c - with . and? name) (95) sh" ("c) - p 60 b5