ML19319C258
| ML19319C258 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 08/01/1969 |
| From: | TOLEDO EDISON CO. |
| To: | |
| References | |
| NUDOCS 8002110722 | |
| Download: ML19319C258 (9) | |
Text
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D-B TABLE OF C0xmns Section Page 10 STEAM AND POWER COUVERSION SYSTEM 10-1 10.1 DESIGN BASIS 10-1 10.2 SYSTEM DESCRIPTION 10-1 10.2.1 TURBINE GENERATOR 10-2 10.2.2 MAIN STEAM PIPING 10-2 10.2.3 MAIN STEAM ATMOSPHERIC DUMP AND TURBINE 10-2 BY-PASS SYSTEM 10.2.4 CONDENSATE AND FEEDWATER SYSTEM 10-3 10.2.5 MAIN TURBINE CONDENSERS lo_h 10.3 SYSTEM RELIABILITY lo-h 10.4 TESTS AND INSPECTIONS 10-4 c
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I Figure No.
Title l-10-1 Flow Diagram, Steam and Power Conversion System i
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i D-B 10 STEAM AND POWER CONVERSION SYSTEM 10.1 DESIGN BASIS The steam and power conversion system is designed to accept steam from the steam generators which is used to produce electric energy by the turbine-generator.
The condenser transfers the heat which is unusable in the cycle to the con-denser cooling water and deaerates the condensate.
The regenerative turbine cycle heats the condensate and returns it to the stesm generators.
10.2 SYSTEM DESCRIPTION Flow diagrams of the system are shown on Figure 10-1.
10.2.1 TURBINE-GENERATOR The General Electric turbine-generator expected maximum capacity (valves vide open rating) vill equal the nuclear steam supply system capability at 2789 megawatts themal rating. The turbine-generator guaranteed rating vill equal the nuclear steam supply system guaranteed rating of 2650 MW thermal.
The turbine is an 1800 rpm tandem compound, four-f b utaust, indoor unit.
Slightly superheated steam is supplied to the turiine from the steam gener-ators through four stop valves and four governing control valves. The steam flows through a two-flow, high-pressure turbine aid then through two com-bination moisture separators-w heaters in parallal to two double-flow, low-pressure turbines which exhaust to the main condedser system. There are provisions for steam extraction for six stages of feedvater heating and two feed pump turbine drives. %e turbine is equippe d with an automatic stop and emergency trip system snich trips the stop ar.d control valves to a closed positon in the event of turbine overspeed, low bearing oil pressure, low vacuum, or thrust bearing failure.
An elecuric solenoid trip is pro-vided for remote manual trips and for various au1.omatic trips.
1 The turbine lubricating oil system supplies oil for lubricating the bearings.
A bypass strean of turbine lubricating oil flove continuously throu6h an oil conditioner to remove impurities.
The generr. tor is direct-connected to the turbine, and has water cooled stator conductors and hydrogen cooling for the rotor and the air-gap. The generator KVA rating vill be sufficient to develop turbine WO capability when operat-ing with 0.90 power factor. At this rating the generator hydrogen pressure vill be 60 psig. The exciter is direct-connected and is of the silicon diode rectifier type. The generator shaft glands are oil sealed to prevent hydro-gen leakage.
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D-B 10.2.2 MAIN STEAM PIPING Steam generated in each of the two steam generators is conducted through the containment vessel and shie} 'i tuilding vall in separate lines.
The steam
. lines are anchored at the snield building vall. The lines have the flexibility to take the relative movement (expansions) of the steam generators. There are spring-loaded steam generator safety valves outside of the containment in each line.
The steam generators' spring-loaded safety valves discharge to the atmosphere and are in accordance with the requirements of the ASME Boiler and Pressure Vessel Code,Section III.
The spring-loe.ded safety valves vill have a total capacity adequate to handle the nuclear steam supply system capacity at 2789 MW thermal rating.
In addition, there is an atmospheric dump velve system and a turbine by-pass valve system (10.2.3) in each steam line, which are set to open at a lower pressure than the' spring-loaded safety valves.
Steam line isolation valves are located downstream of the. code safety valves, the atmospheric du=p valves and the lines to the auxiliary feed pump turbines.
The turbine bypass valves and connections to steam reheaters and auxiliaries are downstream of isolation valves.
Steam is supplied to the high pressure steam reheaters, the gland steam sealing system, the steam jet air ejector and the steam generator feed pump turbines for lov load operation.
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Each of the steam generators leads vill feed two steam turbine stop valves.
There are 4 steam turbine leads starting at t'ese stop valves. There is an equalizing pipe between these turbine leads at the stop valve discharge close coupled with the turbine throttle (governing) valves.
10.2.3 MAIN STEAM ATMOSPHERIC DUMP AND TURBINE BY-PASS SYSTEM There vill be an atmospheric dump valve on each steam line between the con-l tainment and the turbine stop valves. These valves will be used to control cooldown of the steam generator by controlling steam discharge to the atmo-sphere when the main condenser may not be available as a heat sink due to a loss of circulating water due to a loss of electric power.
The atmospheric dump valves vill not be used for cooldovn when the main condenser is available (with no loss of electric power) in which case the turbine by-pass valves will be used.
These valves will operate automatically at a point lower than the normal code valve setting and the set point vill be adjustable downward for cooldown in case they need to be used for cooldown.
They vill be controlled by the Nuclear Steam Supply System steam pressure control instrumentation. They are not used to meet the code requirementc for safety valves, j
The turbine bypass valves discharge steam from the steam headers between the
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containment and the turbine stop valves.to the condenser. These are used I
_during heat-up and start-up and during hot standby of the NSSS. They are used l
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D-B as part of the reactor turbine control system to control pressure during load
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swings. They are normally used to remove decay heat and stored heat from equipment during cooldown. During operation they are under control of the reactor turbine control system. During cooldown they afe manually controlled from the control room.
When the condenser is available, these turbine by-pass valves are the first to relieve excess pressure, in steam generatcrs, followed by the atmospheric dump valves and then the code safety valves.
These turbine by-pass valves have a capacity of 25 percent of steam flow at l8 rated NSSS output at rated conditions.
10.2.h CONDENSATE AND FEEDWATER SYSTEM The condensate is deaerated in the condenser. There vill be approximately 3 minutes of condensate storage in the condenser ho'.well.
Two condensate pumps discharge this through steam jet air ejector and gland steam condensers.
A third condensate pump is on standby, The condensate then goes to two No.1 l 8
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heaters in the condenser necks, condensate polig_i_ng de g alizers and two i
No. 2 heaters in the condenser nec'Es7 The condensate vill go into two No. 3 heaters downstream of the No. 2 heaters.
These two No. 3 deaerating heaters heat and deaerate the condensate using steam from No. 3 extraction point at 1 loada above about 25 percent load. At lower leads steam vill come from an auxiliary header or a higher extraction point. During a cold startup steam from the auxiliary boiler vill be used in the deaerator. The deaerator storage tanks vill hold 5 minutes feedvater requirement, at VWO load.
The feed pump system takes suction from the deaerators through two slow speed booster pumps driven through gear reduction units from the feed pu=p driving turbines. The booster pumps discharge into the full speed feed pumps direct-connected to the driving turbires.
These turbines are variable speed units which are controlled by the integrated control system which controls l8 feedvater flow to the two steam generators.
There are individual control valves to each steam generator to divide flow to the individual steam gener-ators.
The feed pu=p turbines take motive steam from the main turbine system down-stream of the reheaters and ahead of the low pressure turbine sections.
These feed pump turbines ;xhaust into the main condenser.
The two feed pumps dis-charge in parallel trains to the No. h, No. 5, and No. 6 high. pressure feed-water heaters.
Steam 'from the double flow high pressure turbine exhaust is discharged through two separate shells containing combined moisture separators and reheaters.
The reheaters have two stages.
The first reheat stage utilizes steam from the 6th stage extraction and the 2nd reheat stage uses steam from the main steam header.
All dre. ins from the high pressure heaters are cascaded down to the next heater at normal loads ending in the deaerator (No. 3 heater).
The moisture separators drain to No. 5 heaters.
The two reheater sections drain to No. 6 feedwater heaters.
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The No. 2 feedvater heater drains to the No. 1 heater and the No. 1 heater drains are pumped forward.
Amendsen 10-3
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D-B There is a high water level control on each heater to divert drains from any heater to the condenser, in case of high water level. At lover loads some O
of the 2 eaters are drained to the condenser. The operator =ay want to by-
.j pass all heated drains to the condenser for purification at loads below 30 or 40 percent when starting up and shutting down the unit.
10.2.5 MAIN TURBINE CONDENSERS The main turbine steam condenser system is supplied with cooling water by 8\\
the condenser system described in Section 9 3.2.1.
It is of the deaer-ating type and is sized to condense exhaust steam from the main turbine and from the feedvater pu=p driving turbines under full-load conditions.
It also provides for condensing the steam bypassed by the turbine by-pass valves.
Condenser vacuum holding is accomplished by steam air ejectors. Off gases from the condenser are monitored for radiation at the air ejector discharge.
The condenser hotwell is a storage reservoir for deaerated condensate which supplies the condensate pu=ps.
Deaerated condensate is also stored in the deaerator storage tanks.
6 l This supply of condensate is backed up by two large condensate storas:e tanks from which condensate may be admitted by gravity and vacuum drag into the condenser for deaeration.
10.3 SYSTEM RELIABILITY The components of the steam and power conversion systems are conventional and of a type that have been extensively used in fossil fuel plants and in other nuclear power plants. Adequate instruments, controls and protective devices are provided to assure reliable and safe operation. The equipment in this section vill be designed to applicable codes and standards as listed in 9 and to the best co=mercial standards and practices. The feedvater heaters will be to the standards of the closed Feedvater Heater Section of the Heat Exchange Institute and to the ASME Boiler and Pressure Vessel Code,Section VIII. The condenser vill be to the standards for Steam Surface Condensers of the Heat Exchange Institute.
The station can carry more than half load with one string of the feedvater 8l heaters shutdown and isolated entirely from the system, with two condensate pump shutdown, and with the one steam generator feedvater pump shutdown.
10.h TEST AND INSPECTIONS Most components vill receive inspection at vendors' plants.
Careful super-vision and inspection will be exercised during erection.
The motor-driven pumps and controls will be given pre-operational tests after erection and before plant varm-up.
Condensers, heat exchangers, and piping vill be leak and pressure tested.
Functional tests of the condensate and feedvater system vill be made in connection with initial testing (see paragraph 13.1) of Nuclear Steam Supply System.
Amendment No. 8 Q3
D-B I
The turbine stop valves, reheat intercept valves, extraction line non-return valves, main steam by-pass system and auxiliary feedvater system may be tested while the turbine is in operation.
Operating instrumentation vill be adequate to permit the operators to monitor the component and station performance. Equipment, instruments and controls vill be regularly inspected and monitored to insure proper functioning of components and systems.
' Checking and recalibration of instruments and controls will continue durin6 operating periods as well as during shutdown periods.
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