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Main Condenser
ILT '09
31
Other
Not Applicable
03/01/2008
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Cards

Term
Function of main condenser
 Definition
  • Heat sink for main steam cycle;
  • Removal of non-condensable gases;
  • Central collection point for system drains;
  • Heat sink for bypass steam from nuclear boiler.
Term
Sources of non-condensable gases
 Definition
  • Leaks in mechanical joints;
  • Disassociation of water occurring in the reactor;
  • Fission product leakage in the reactor.
Term
Why are there two separate bonnet water boxes for each condenser?
 Definition
So that half of the unit may operate while the other half is out of service.
Term
Description and purpose of exhaust expansion joints (dog-bone).
 Definition
Rubber belt type expansion joints between turbine exhaust hoods and condenser steam inlets to compensate for any relative movements resulting from thermal expansion.
Term
Condensate flow path inside condensers
 Definition
  • Low pressure condensate is routed to the hotwell of the high pressure shell where it is reheated and combined with the high pressure condensate;
  • The mixture is deaerated and flows from HP storage area to the LP storage area, then to the suction of the condensate pumps.
Term
Basis for the normal hotwell level
 Definition

Provides approximately three minutes pumping with both condensate pumps at capacity

(7300 gpm each).
Term
Hotwell level control band
 Definition

Makeup at +3 inches (instrument) and reject at +6 inches (instrument).

 

NOTE: instrument reference (zero mark) is 27 inches off bottom of hotwell.
Term
When should the MVP NOT be operated
 Definition
When reactor power is above 5% and suction valves (OG-22-1 and OG-22-2) are OPEN.
Term
What is the concern with operating the MVP above 5% thermal power?
 Definition
Significant amounts of hydrogen and oxygen are present in the condenser. Operation with the suction valves open could result in a detonable concentration of hydrogen and oxygen at atmospheric pressure in the pump (which is not explosion proof).
Term
Vacuum that can be maintained by MVP
 Definition
23 inches of Hg vacuum with turbine shaft sealed.
Term
Interlock between MVP and backwash receiving tank vent line isolation valve, OG-28.
 Definition
MVP can not be started if OG-28 is not in full closed position.
Term
MVP trips
 Definition
  • High main steam line radiation;
  • Any Group II PCIS signal:
    • high drywell pressure;
    • low reactor water level;
    • reactor building exhaust plenum high rad (one up or two down);
    • Fuel pool high rad (one up or two down).
Term
What happens on a MVP trip?
 Definition
  • MVP trips;
  • Suction valves close;
  • MVP recirc seal pump trips
Term
Which part of PCIS logic trips the MVP pump?
 Definition
Div II
Term
Which part of PCIS logic trips the MVP suction valves?
 Definition
Div I
Term
Which part of PCIS logic trips the MVP recirc seal pump?
 Definition
Div I
Term
Possible result on a loss of PCIS division I logic
 Definition
MVP Recirc Seal pump will trip and MVP suction valves will close which results in MVP operating with no seal water which may result in damage to the MVP.
Term
Steam pressure required for steam jet air ejectors to properly remove non-condensable gases and vapor from main condensers
 Definition
125 psig
Term
Purpose of steam jet air ejectors
 Definition
Continuously remove air and other non-condensable gases that collect in the main condenser.
Term
When is air ejector system placed in service?
 Definition
Once turbine shaft is sealed and sufficient steam pressure (above 150 psig) is available.
Term
With a minimum amount of condenser air in-leakage, what vacuum can air ejectors maintain?
 Definition
26 inches Hg or greater
Term
Trip signals to AO-1085A(B), located on the common suction line to the second stage jets.
 Definition
  • Offgas pretreatment radiation monitors after a 30 minute time delay;
  • Low steam jet air ejector supply pressure (110 PSIG) for 5 seconds.
Term
Power supply to MVP
 Definition
Load Center 101
Term
Power supply to Condenser off-gas suction valves
 Definition
Y-20
Term
Power supply to vacuum breakers (A and B)
 Definition
Each come off MCC-121
Term
Power supply to Condenser Low Vacuum Trip Reset
 Definition
D21
Term
When is MVP required?
 Definition

To maintain condenser vacuum when steam pressure is not sufficient to allow SJAEs to operate satisfactorily (up to 150 psig).

 

However, MVP SHALL NOT be operated when Reactor Thermal Power is greater than 5%.
Term
Basis for MVP trip on high radiation from MSL rad monitors.
 Definition
To limit control room and offsite dose in the event of a DBA Control Rod Drop Accident.
Term
Basis for MVP trip on group II isolation signal
 Definition
Operation of the MVP simultaneously with Standby Gas Treatment will cause low flow in SBGT system.
Term
What is the concern with operating the MVP with the reactor de-pressurized and a clear path from reactor to condenser?
 Definition
Could create a vacuum in the reactor. If vacuum exceeds 11 inches Hg, then SRVs can open resulting in flow path between drywell and condenser via SRV discharge line vacuum breakers.
Term
Major nuclear concern with SJAE steam flow and deaerating steam flow.
 Definition
Both are inputs to nuclear instrumentation (IRM) heat balance. Any changes to these parameters will affect calculated thermal power.
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