VGB POWERTECH 5 (2021) - International Journal for Generation and Storage of Electricity and Heat

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VGB PowerTech 5 l 2021
Safety-related residual heat removal chains for pressure water reactors
DWR 1,300 MW
Reactor
CNA 2
Reactor
SG
RCP
SG
RCP
1 2
6
HPT
FWT
HPT
FWT
RH
In order to complete the comparison, the
water/steam cycle must also be included.
3
3
M
S
4 5
4
M
S
5
LPT
LPT
G
G
Steam Systems
Reactor Coolant System
Moderator System
Feedwater System
Main Condensate System
Main CoolingWater System
G
SG
RCP
RH
FWT
HPT
LPT
MS
1
2
3
4
5
6
Generator
Steam Generator
Reactor Coolant Pump
Reheater
Fee Water Tank
High Pressure Turbine
Low Pressure Turbine
Moisture Separator
Moderator Pump
Moderator Cooler
Main Feedwater Pump
Low-Pressure
Feedwater Heater
Main Condensate Pump
High-Pressure
Feedwater Heate
Fig. 11. DWR 1,300 MW- CNA 2, Comparison of Water/Steam Cycles (simplified).
By using the Moderator Cooler for preheating
the feed water, the PHWR is considerably
simplified in comparison to the PLWR
(F i g u r e 11 ). In addition to the High Pressure
Preheaters themselves, the steam extraction
points on the high-pressure section
of the steam turbine and the connecting
steam pipes are eliminated for the PHWR.
The second above item determines the
number of pumps that are to be operated
continuously, and thus also the electrical
auxiliary power demand as well as the net
efficiency. This in turn influences the economic
attractiveness of the plant.
Explanations to F i g u r e 10 :
––
Thick drawn subsystems and components:
Used in power operation
––
Thin drawn subsystems and components:
Ready for operation readiness
––
Thin drawn heat exchanger edging, but
with thick drawn flow symbol: Flow
through its secondary side, but without
heat input
For DWR 1,300 MW, the upper part of
F i g u r e 10 shows the minimum amount
of subsystems to be operated.
It is assumed that
––
The fuel pool cooling circuit connected
to the Operating Component Cooling
System is sufficient to maintain the fuel
Tab. 1. DWR 1,300 MW – CNA 2, Comparison of RHR Chain functions.
RHR-
C
System (Design)
Functions
– Power Operation
– Shut down
operation
– Plant Accidents
– Civilization-related
External Impacts
RHR Control
System (Design)
Functions
– Power Operation
– Shut down
operation
– Plant Accidents
– Civilization-related
External Impacts
RHR Control
System (Design)
Functions
– Power Operation
– Shut down
operation
– Plant Accidents
– Civilization-related
External Impacts
RHR Control
DWR 1,300 MW CNA 2
Residual Heat Removal System (MP/MT)
Fuel Pool Cooling (FPC*)
Reactor Cooling via RHR Chain,
FPC*
Reactor Cooling via Emergency RHR Chain,
FPC*
at Primary Side of Residual Heat Exchangers
Nuclear Component Cooling System (LP/LT)
Safety Component Cooling System (SCCS)+ Operation Component Cooling System
(OCCS)
Supply of OCCS, and possibly of 1 RHE for FBC* in
case of and very high cooling water temperatures
Heat Transfer via RHR Chain,
Supply of OCCS (if possible)
Heat Transfer via Emergency RHR Chain
---
Heat dissipation from SCCS (sources: OCCS and
possibly FPC*), and from SCCWS to the heat sink
Heat dissipation via RHR Chain and from SCCWS
to the heat sink
Heat dissipation via Emergency RHR Chain,
to the heat sink
---
Secured Service Cooling Water System (LP/LT)
Moderator System (HP/HT)
Feed Water Preheating through Moderator Cooling
Reactor Cooling via RHR Chain
---
Supply of OCCS,
Supply of SCCS consumers in all of ist
subsystems
Supply of OCCS (if possible),
Supply of SCCS consumers in all of ist
subsystems
---
RHR Intermediate
Cooling System (HP/HT)
Heat Dissipation via all subsystems from SCCS (incl. OCCS), SCCWS
and FPC to the heat sink
Heat dissipation via RHR Chain and from SCCS (possibly incl. OCCS),
SCCWS and FPC to the heat sink
---
Only Feed Water pass-through
at Moderator Cooler
Heat Transfer via RHR Chain
at Primary Side of the RHR Intermediate
Cooling Heat Exchanger
MP/MT: Medium Pressure/MediumTemperature HP/HT: High Pressure/HighTemperature LP/LT: Low Pressure/LowTemperature FPC: Fuel Pool Cooling
*: Assumption, that Fuel Elements are stored RHE: Residual Heat Exchanger RHR: Control of Heat to be dissipated via RHR Chain/RHR Line
SCCWS: Secured Closed Cooling Water System (Cooling of Diesel Engines and Secured Chilled Water System)
55