TS tidings January 2012 - BHEL - PSSRinterweb.bhelpssr.co.in/BusinessExcellence/Technical Services... · 1 JANUARY 2012 TS TIDINGS ... manual and momentary paralleling operation was

1 JANUARY 2012 TS TIDINGS

TECHNICAL SERVICES / PSSR

NALCO CPP, ANGUL JANUARY: 2012 VOLUME : 15.08

Published by Technical Services / PSSR For internal circulation

HIGHLIGHTS

BELLARY 500 MW UNIT 2:

TURBINE WAS PUT ON BARRING GEAR.

UNIT WAS SYNCHRONISED AND LOADED TO 103 MW.

SIMHADRI STAGE II, 2 X 500 MW, UNIT 4:

STAGE – 1 STEAM BLOWING WAS STARTED AND ONE TRIAL BLOW WAS GIVEN ON 30.01.12.



INSIDE

1. STATUS OF PROJECTS COMMISSIONED / TO BE COMMISSIONED DURING 2010 - 2012.

2. SERVICE RENDERED TO OTHER REGIONS/SAS/PROJECTS AFTER CONTRACT

CLOSING/CUSTOMER TRAINING.

3. APPRECIATION FROM CUSTOMER FOR SERVICES RENDERED.

4. FEED BACK ON EQUIPMENTS FROM SITES.

5. LET US KNOW. KUDANKULAM NUCLEAR REACTOR SAFETY FEATURES Feed backs and suggestions from all departments of BHEL for improvement of TS TIDINGS are welcome and may please be addressed to ADDL. GENERAL MANAGER (TSX)/BHEL-PSSR/CHENNAI



STATUS OF PROJECTS COMMISSIONED / TO BE COMMISSIONED DURING 2010 – 2012:

BELLARY 500 MW UNIT 2:

TURBINE WAS PUT ON BARRING GEAR ON 09.01.2012.

TDBFP – A: Lube oil tank cleaning was completed.

FD fan A: 8 hours trial run was completed.

Leak off steam system hydraulic control valve commissioning was completed.

Gland steam condenser second exhaust fan was commissioned.

RODM plant: Ultra filtration system was charged, flushing up to RO stage - I & II HP pump was completed. Membrane loading was completed. MD reservation pump – 2 nos. trial run was completed. Ultra filtration plant was started and SDI (Silt Density Index) achieved. Resin loading was completed in mixed bed system. RODM plant was commissioned and DM water generation was started

Extraction to Deaerator, APRDS to Deaerator pegging and TDBFP suction lines steam flushing was completed.

GD test of ESP- A & B pass was completed.

SH & RH spray piping steam blowing was carried out.

Furnace leak test was conducted. Duct leak test was carried out up to APH inlet.

Mill – C & D 8 hour’s trial run was completed.

Coal handling plant 11kV HT switch gear and MCC – 7 were charged

GRP relay testing was carried out.

Boiler hydro test was carried out at 185 ksc.

Bearing vapour extraction fan - 2 nos. were commissioned.

DG set local panel testing was carried out.

Ash handling system: 1 no. LP pump trial run was carried out. Ash slurry pumps of B stream stage 1 & 2 were run. Seal water pump was run. Seal water pump 2 nos. were run. Ash slurry – A stream pumps – 1 & 2 trial run



completed. B stream stage - 1 pump run for one hour. Disposal pipe leak test was carried out

VFD transformer was charged.

HFO guns were established.

ESP C pass: 11 CERMs, 18 EERMs & 1 GDRM coupled trial run was completed.

ESP D pass HVRs (High Voltage Rectiformers) 10 nos. were commissioned.

Seal air fan – B motor trial run was completed.

Generator Transformer – Stability test was completed.

Generator Transformer Back Charging was completed.

Generator – 72 hours air leak test was completed.

Generator H2 gas analyzer was commissioned.

Governing system commissioning was completed.

HRH safety valve (1 no.) floating was completed.

Generator gas filling was done.

Generator electrical tests (OCC & SCC) were completed on 26.01.12.

UNIT WAS SYNCHRONISED ON 27.01.12 AND LOADED TO 103 MW.

CPCL PHASE 3 - UNIT 4:

GT: Accessory compartment vent fan – 2 trial run was completed. Enclosure sealing work was completed. Balance drives remote commissioning from mark VI was completed.

Remote commissioning of BOP drives ( 9 nos. ) from Hardwired console panel at Main control room was completed.

Naphtha forwarding pump motor trial run was completed.

GT skid drain line piping to drain tank was completed.

Mark VI to DCS serial communication was established and address mapping was completed.

Fuel and Gas PLC to DCS serial communication was established with sample tag.



HSD centrifuge 1 & 2 ball assembly was completed.

HSD drain tank pump motors 1&2 trial run was completed.

Fire & Gas: PLC logics and interlocks demonstration for GT – CO2 system to customer was completed.

Max DCS based SCADA panels was charged.

Max DCS to Honeywell F & G PLC, mod bus communication was established through RS-485 link through MAX switch.

Remote operation of breakers of 415V PMCC was carried out from Max DNA based SCADA system.

Naphtha pump motor – 1 high vibration problem was resolved and motor trial run was completed.

BOP logics and interlocks protection for HSD and cooling water drives demonstrated was completed from PLC.

AC ventilation system MCC wiring modifications were completed by M/s C & S representative.

HSD drain tank – radar type level submitters – 2 nos. were commissioned.

LP steam line to Deaerator hydro test was carried out.

Attending to customer punch list points as per format - 3 in HSD tank area was completed.

GT on-base to off-base skid trip oil and hydraulic oil lines cardboard blasting was completed.

Instrument air line card board blasting was completed up to HSD tanks.

CO2 flood test inside GT was carried out. Leakages found inside accessory compartment are being attended.

415V PMCC: Auto, manual and momentary paralleling operation was checked.

Commissioning of Hard wired console panel – 1 at main control room up to PLC was completed.

Remote commissioning of HSD drain tank pump 1 & 2 and Naphtha forwarding pump 1 & 2 was completed.



MRPL: 1XFr.5 GTG, 2X28.5 MW STG, 4X270 TPH UTILITY BOILERS, 1X85 TPH HRSG, and ADDITIONAL ORDER: 1XFr.6B GTG, 1X85 TPH HRSG-GT1.

Calibration of all the instruments in water wash, Water injunction skid and LGO, LCO filter, skid was completed.

AOP motor trial run was completed.

Frame 5 GT lube oil flushing started on 29.01.12 and is in progress.

PMCC-4(415 V) incomer-1, incomer-2 and BUS coupler numerical relays configuration and testing was completed.

AC MCC inter panel wiring was completed. DC bus charged and scheme checking was completed.

Ventilation MCC inter panel wiring completed, DC bus charged and scheme checking completed.

6.6 kV switch gear numerical relay testing was completed.

NEYVELI TS II EXP CFBC, 2 X 250 MW, UNIT 1:

CFBC was boxed up since 24.09.11 to attend to shut down jobs and rectification works.

CEP – 1B: Mechanical seal replacement was completed.

Seal-pots inspection and closing of manhole doors was completed.

CFBC was lighted up on 23.01.2012 for dry out of newly applied refractory.

All FBHEs blowers were run and air flow through them was established.

Unit was synchronized on 25th & 26th January 2012 and kept in service for 2 – 3 hours. Unit was tripped on 26.01.12 due to abnormal difference in metal temperature measurement at steam cooled walls left and right. Matter is being analyzed by M/s Lentjes & BHEL/Trichy.

CFBC was in service at 55 MW with FBHE and without oil support.

CFBC was running a 115 MW and tripped on 01.12.12 due to HP stop valve -1 metal temperature TC loose connection problem. Unit was restarted and turbine was rolled to 600 rpm.



NEYVELI TS II EXP CFBC, 2 X 250 MW, UNIT 2:

TG-MOT cleaning was completed.

Centrifuge was commissioned and MOT filling was completed.

AC EOP was run and oil leakages are being attended.

RINL:

TB – 4:

Testing (Ratio test, OCC) of 06/06 nos. 11 KV/415V Dry type transformers for station board was completed through temporary supply.

Condensate line and Extraction normalization was completed.

Governing oil line was charged and valve operation was checked. Lube oil temperature control valve was commissioned.

LPH drip line normalization was completed.

Condensate system: hydro test from drain cooler to end connection, condensate line from ejector to drain cooler line, CEP discharge line hydro test was completed.

Extraction -2 line hydro test was completed.

CEP suction line flushing was completed.

Condensate line control valves commissioning was completed (Hot well level and LP heater to flash tank was commissioned).

CEP – A & B interlock and protection checking was completed.

Condenser flood test was completed.

Seal steam system control valves were commissioned.

Turbine Drain MOVs commissioning was completed.

SG – 6:

ID fan – A: Stage – II lube oil flushing was completed.

ESP Pass B: CERM motor trial was completed.

FD fan – A stage II flushing was completed.



MS line internal hydro test in the presence of Boiler Inspector was completed.

Boiler LT-MCC testing was completed. Valves and dampers commissioning was completed.

Station Transformer -1&2: (10 MVA) oil filtration was completed.

20 MVA transformer oil filtration was completed.

CRP: 11kv/6.6 kV Numerical relay testing is in progress.


Unit is presently running at full load.

Mill – K: 8 hours trial run and ring roll setting were completed.

Feeder K preparatory works in progress for trial run.


HFO station steam blowing was completed.

PA fan – A & B and PAPH – B Lube oil lines acid cleaning was completed.

MDBFP: oil flushing was completed. Motor trial run, Hydraulic coupling trial run were completed.

SAPH A: trial run with AC motor was completed

Boiler drum and ring header were boxed up after completion of orifices.

Safety valve HT plugs removal and disc fixing – 6 nos. of drum and 2 nos. of SH were completed.

MS stop valve (MS1 & MS2) were commissioned.

Electrically Operated Temporary Valves (EOTVs) were erected.

H034 CD elevation and OS34 CD elevation remote commissioning completed.

All temperature and pressure measurement points for steam blowing were made through from MAXDNA.

PAPH B Guide bearing oil flushing was started and in progress. Support bearing lube oil motor - 2 nos. trial run was completed.



EOTV (L) commissioned from remote.

ID fan – B, FD fan – B and SAPH – 4B were run for 30 minutes and air flow was established.

PA fan 4B: Stage 1 lube oil flushing was carried out.

CD & EF elevation oil guns were proved with LDO.

STAGE – 1 STEAM BLOWING WAS STARTED AND ONE TRIAL BLOW WAS GIVEN ON 30.01.12.

Mill – A Motor: 8 hrs. trial run was completed.

FW system steam flushing: BFPs discharge line, HP inlet, outlet and bypass lines Suction line flushing was completed and strainer was boxed up.

TG: AOP 1 & 2, DCEOP & ACJOP motor trial run was completed.

TG: MOT cleaning and inspection completed.

TG lube oil lines and card board blasting and normalization completed.

TG oil flushing was started on 16.01.2012.

TG AOP1 & AOP 2– 8 hours trial run was done with TG lube oil flushing.

TG lube oil flushing was temporarily stopped on 28.01.12 to include coolers and for thermal shock arrangements.

TG DMCW – B trial run was completed.

TG DMCW A, B & C: Motor trial run was completed.

TG-DMCW flushing was completed. VALLUR 3 X 500 MW, UNIT 1:

PAPH – 1B: lube oil lines acid pickling was completed. Seal setting was completed

PA fan B: Instrumentation work was completed. lube oil flushing was declared completed

ESP C pass: Emitting Electrode Rapping Motors (EERM) 19/20 trial run was completed.

ID fan A Lube oil lines acid cleaning was completed.



Mill A Stage – II and Mill – B Stage – 1 lube oil flushing was completed.

Mill A: 8 hours trial run was completed.

Mill B: Main motor 8 hours trial run was completed. Stage – II lube oil flushing was completed

Vacuum pump – A & B motor trial run was completed.

Turbine lube oil lines hydro test was completed.

Jacking oil line hydraulic test was completed at 200 Kg/cm2 pressure. Turbine oil is drained and MOT fresh oil filling was in progress.

Control fluid system main motor trial run was completed.

Control fluid system – Air leak test of 8 and 32 bar system was carried out.

Control fluid system: Flushing was commenced and is in progress.

HP Turbine, ES, HPCV and IPCV insulation and cementing was completed.

Generator PW system: 72 hours hot water flushing was completed. Hydrotest and N2 gas purging was completed.

Condenser fill test was completed.

Condenser deck spring releasing was started on 28.01.12.

Auxiliary Boiler: Hydro test & FD fan motor trial run was completed.

SERVICES RENDERED TO CUSTOMER /SAS/MUs:

--- NIL ---

CUSTOMER TRAINING & TECHNICAL PAPER PRESENTED:

--- NIL ---

APPRECIATION FROM CUSTOMER FOR SERVICES RENDERED :

--- NIL ---



FEED BACK NO.1

PROJECT: 1X500 MW BELLARY THERMAL POWER PROJECT STAGE-II PROBLEM: GENERATOR TRANSFORMER SUDDEN SURGE RELAY OPERATION DURING INITIAL BACK CHARGING STATUS:

In 500 MW project 3 nos of 124.2/165.6/207 MVA,No Load Voltage (HV): 400/ √3 KV (LV): 21 KV single phase transformers are used to export the Power generated from Generator. In one of our 500MW projects, after completion of all erection activities, Oil filtration and other checks like Tan delta, winding resistance, IR value, Temp protections of winding & oil, surge relays etc., and operation of GCB at 400KV side in switchyard including checking of all protections, and after demonstrations of Firefighting device the Generator Transformer is declared fit for charging and synchronization. PROBLEMS FACED: During first charging, with all protections and safety precautions, the Generator Transformer Breaker close command is given. But immediately after closing, the “B” Phase of Generator Transformer Tripped on Sudden Surge relay operation. It is common that the tripping of Higher rated Transformers on sudden surge protection during the First time operation after long time. All Bucholz’s relays were checked & entrapped air is removed in Bucholz’s relays & sudden surge relays.Once again all the transformers were checked physically B phase transformer was checked physically with utmost care and clearance was given for charging. Again, second time the same B phase transformer tripped on sudden surge protection. ACTION TAKEN: Since both times only the B phase transformer has tripped on sudden surge protection, the following action was planned before going for further charging.



1. Checking of Surge protection relays in all the phases and replace the sudden surge protection relay in B phase.

2. Check the entire HT circuits starting from switch yard.

The sudden surge relay of B phase was replaced suspecting its malfunction and other surge relays were checked and found in order. The generator Transformer was isolated from HT side and 400 KV switch yard supply is extended. The voltage is measured through capacitor voltage Transformer (CVT) available in the Switchyard. It was noticed that the B phase voltage is not study whereas the other two phases are found ok. We decided to check the B phase CVT. Line Permit was availed and the CVT of B phase was checked. On inspection it was found that the LINK 1(scheme attached) provided on the HT side in series with the reactor was found loose, which was opened earlier for Tan delta measurement of CVT and while normalizing, this link was not tightened properly. The link contact portion was cleaned and all the links tightness were checked in all CVTs and again charged the Line without Generator Transformer. Now the voltage was found to be uniform and stable. Then, Generator Transformer was connected and charged. All parameters were found normal and no abnormality was noticed. After checking of synchronizing circuit, the entire system was cleared for synchronizing and further full load operation.





FEED BACK NO. 2

PROJECT: 1X500 MW BELLARY THERMAL POWER PROJECT STAGE-II PROBLEM: SITE MODIFICATION CARRIED OUT IN 100% STATOR EARTH FAULT(SEF) OF M/S ABB RELAY REG 316 Introduction: At 1x500MW BTPS Stage-II, 100% Stator Earth Fault (SEF) protection is provided using M/s ABB make relay REG 316. As per GRP scheme shown in Fig 1, 3.4 V AC 12.5HZ will be injected to stator circuit through M/s ABB supplied Resistor Unit. Problem Faced: Site erected the Voltage Injection Unit near GRP panel at EL 17Mtr. NGT located at EL 8.5 Mtr. As per PEM cable schedule from Injection unit to NGT site laid 2.5sqmm CU cable approximately 250mtr. During calibration of stator earth fault parameters required by REG316 relay i.e MTR-Measurement Transformer Ratio & R’Es- Measurement Resistance site was not able to get the required parameters. As per PEM settings MTR should 40 and R’Es must be of 4.5KOhm. Site was unable to test this protection, since the relay was measuring earthing resistance as >30 kΏ, even though dead short was simulated in primary / secondary of NGT. Analysis: 1) It is observed that NGR is in parallel with M/s ABB supplied Resistor Unit which

is not meeting the scheme requirement Ref Fig 1A.

2) The distance between the injection unit & NGT is 250 mtrs which caused drop in injection voltage across the resistor unit.



Solution:

1) Voltage Injection Unit is shifted near to NGT cubicle at EL 8.5 mtr.

2) 90 Sqmm Cu Cable used between NGT & Injection Unit to avoid the injection voltage drop.

3) On detailed analysis considering the Earth fault Current limiting requirement BHEL supplied NGR only used and M/s ABB supplied Resistor unit removed.

Final Implementation: Final implemented 100% SEF circuit as shown in Fig 2. Conclusion: 100% SEF parameters MTR & R’Es achieved and SEF protection proven online.



Fig. 1- BTPS-2 GRP Scheme



Fig 1A- M/S ABB Relay Scheme along with NGR

R’Es & R’Ps is part of M/s ABB Supplied Resistor Unit.

NGR



Fig 2- Final implemented circuit

90Sqmm Cu Cable. R’Ps & R’Es is part of NGR at different tappings. R’Ps = 42milli ohm R’Es= 125 milli ohm.



KUDANKULAM NUCLEAR REACTOR SAFETY FEATURES

INTRODUCTION

Kudankulam nuclear thermal power plant is having VVER type reactor. There are 25 VVER 1,000 MW reactors are in operation now at five countries. Nine more are under construction. The version offered to India is the recent and has more advanced safety features. These reactors belong to the Generation 3 + category (with more safety features than Generation 3) with a simpler and standardized design.

Kudankulam site is located in the lowest seismic hazard zone in the country. The water level experienced at the site due to the December 26, 2004 tsunami, triggered by a 9.2 earthquake was 2.2 meters above the mean sea level. The safety-related buildings are located at higher elevation (Safety Diesel Generators,9.3 meter) and belong to the highest seismic category and are closed with double sealed, water leak tight doors.

The reactors have redundant, diverse and thus reliable provisions needed to control nuclear reactions, to cool the fuel and to contain radioactive releases. They have in–built safety features to handle Station Black Out.

Besides fast acting control rods, the reactors also have a “quick boron injection system”, serving as a back-up to inject concentrated boric acid into the reactor coolant circuit in an emergency.Boronis an excellent neutron absorber.

The enriched uranium fuel is contained in Zirconium-Niobium tubes. It can retain the radioactivity generated during the operation of the reactor. The fuel tubes are located in the 22 cm thick Reactor Pressure Vessel (RPV) which weighs 350 tonnes. RPV is kept inside a one metre thick concrete vault.

The reactor has double containment, inner 1.2 metre-thick concrete wall lined on the inside with a 6 mm layer of steel and an outer 60 cm thick concrete wall. The annulus between the walls is kept at negative pressure so that if any radioactivity is released it cannot go out. Air carrying such activity will have to pass through filters before getting released through the stack. Multiple barriers and systems ensure that radioactivity is not released into the environment.



KKNPP-1&2 has many new safety systems in comparison with earlier models. The Four-train Safety-System instead of just one system leads to enhanced reliability. The reactors have many passive safety systems which depend on never-failing forces such as gravitation, conduction, convection etc.

Its Passive Heat Removal System (PHRS) is capable of removing decay heat of

reactor core to the outside atmosphere, during Station Black out (SBO) condition lasting up to 24 hours. It can maintain hot shutdown condition of the reactor, thus, delaying the need for boron injection. It works without any external or diesel power or manual intervention.

The reactors are equipped with passive hydrogen re-combiners to avoid

formation of explosive mixtures .The reactors have a reliable Emergency Core Cooling System (ECCS).

Core catcher Located outside the reactor vessel, a core catcher in the form of a vessel

weighing 101 tonnes and filled with specially developed compound (oxides of Fe, Al & Gd) is provided to retain solid and liquid fragments of the damaged core, parts of the reactor pressure vessel and reactor internals under severe accident conditions.

The presence of gadolinium (Gd) which is a strong neutron absorber ensures that the molten mass does not go critical. The vessel prevents the molten material from spreading beyond the limits of containment. The filler compound has been developed to have minimum gas release during dispersal and retention of core melt.

SALIENT FEATURES OF VVER

VVER is an acronym for “Voda Voda Energo Reactor” meaning water-cooled, water moderated energy reactor. This type of reactor uses 3.92% enriched uranium as fuel. The VVER reactors belong to the family of the pressurized water reactors (PWRs), which is the predominant type in operation, world over. The advanced 1000MWe design of VVER (VVER-1000) has many variants in different countries, which are derived from the basic VVERmodelV-392. The models of these plants have some modifications based on the client–country requirement (Information, 1998; KK-Proj. Tech. Assign., 1998). The VVER reactor is an advanced PWR, i.e., VVER NSSS model Version V-412, which incorporates all the features of a modern PWR as per the current Russian, Western and IAEA standards. The KK-VVER has a 3 year fuel cycle. This reactor requires annual refuelling of one-third of the core, i.e., approximately 55 fuel assemblies. The reactor plant consists of four circulating loops



and a pressurizing system connected to the reactor with each loop containing a horizontal steam generator, a main circulating pump and passive part of emergency core cooling system (accumulators). The loops are connected with the reactor pressure vessel assembly by interconnecting piping. The reactor plant also consists of a reactor protection and regulation system, engineered safety features, auxiliary system, fuel handling and storage system, etc. (KK-PSAR, 2002). SAFETY FEATURES OF VVER The design features for the KudanKulam plants have been extensively negotiated. These include: • Compliance of all the regulatory requirements of India. Its designs have to be licensed by our independent regulatory body. • Capability to operate with high performance, reliability and safety within Indian grid conditions. • Latest design features that meet international safety requirements. • Basing the plant on the most reliable and safe PWR technology, which uses ordinary water for cooling and moderation purposes. 1. The general design concepts of safety systems

The VVER reactor that is under construction at KudanKulam site is an advanced PWR, i.e., VVER NSSS model Version V- 412, which incorporates all the features of a modern PWR as per the current Russian, Western and IAEA standards. The general design concepts of the safety systems in the KK-VVER are:

• The safety systems are designed on fail-safe principle and are capable to function under loss of power supply.

• Each active safety system has four trains 4×100%, i.e., each capable to perform completely the intended safety function except few like emergency boron injection system which has 4×50% capacity.

• The number of the safety trains is chosen proceeding from the consideration that one train may not be available due to single failure criteria, another may not be available due to maintenance and the third may be knocked out because of apostulated initiating event.

• Each active safety system is backed up by passive safety system and each is capable to perform the intended safety function.



• The safety system trains are completely segregated in terms of physical location, layout and source of motive force.

• The design of control safety systems are such that a failure in the system causes actions directed to ensure safety.

• The safety system actuates on demand automatically and operator actions to disable an automatically actuated safety system are blocked in the first 30 min to exclude personnel error.

• All safety systems are supplied with power from independent sources (dedicated diesel generators), designed in accordance with the requirements of the protective safety systems.

• The core damage frequency (CDF) of the nuclear power plants as per the Russian regulatory requirement is less than10−5/reactor-year. However, the safety approach adopted in the design of “KudanKulam” NPP resulted in a calculated CDF of 10−7/reactor-year. This approach involves different principles of operation of safety systems (active and passive)and minimizes common-cause failures. Some of the active safety system functions are combined with normal operation functions, with a view to increase functional reliability. In such cases, the design provides fulfilment of safety functions with minimum number of changes of valves positions.

2. Engineered safety features

The engineered safety features are provided to mitigate and limit the

consequences of abnormal conditions including accident condition. This task is accomplished by making the reactor sub-critical, cooling and maintaining the level in the core, limiting the rise of fuel temperature, containing the radioactivity release from the core and safeguarding various system from overpressure. The KudanKulam-VVER-1000 incorporates advance engineered safety features apart from standard safety features of PWR’S. 2.1. Emergency core cooling system

The emergency core cooling system provides core cooling under a wide ranged of postulated accidents involving leaks of primary system. In the case of loss of coolant accident (LOCA),borated cooling water is injected into the reactor core to remove the decay heat and to preserve core integrity. The emergency core cooling system comprises of the following sub-systems:



(i) High-pressure emergency injection; (ii) High-pressure accumulator injection (passive system); (iii) Low-pressure accumulator injection (passive system); (iv) Low-pressure emergency injection and long-term recirculation. (i) High-pressure emergency injection system.

The high pressure emergency injection system is designed for performing the function of high-pressure emergency core cooling system during an event of loss of coolant accident. In case of LOCA, this system provides borated water (with concentration of 16 g/kg) at an injection pressure of 7.89MPa into the primary circuit from the spent fuel-cooling bay. This system has four independent physically separated trains. Each system train includes the emergency boron injection pump, pipelines, valves, heat exchanger, etc. The heat exchanger is shared by the corresponding train of the high- and low-pressure injection systems, containment spray system and high-pressure emergency boron injection system. This system draws borated water from the spent fuel-cooling bay through suction line of low-pressure injection system and utilizes the same shared heat exchangers with other systems. The pump has a recirculation loop, which is normally open, and as the flow gets established during a LOCA the recirculation line gets closed. This high-pressure injection system in case of a LOCA injects into the main coolant inlet pipelines and the rated for ECCS injection gets over the suction is automatically switched over to the containment sump capacity of the pumps are 214m3/h. In case the 500m3of spent fuel bay water available.

(ii) High-pressure accumulator injection system.

The high-pressure accumulator injection system (passive core cooling system) is intended for quick supply of borated water into the reactor core for cooling and filling during a loss of coolant accident. This system automatically starts injecting borated water when the primary circuit pressure falls below 5.89MPa during a LOCA. It consists of four independent physically separated trains. This system is riding over the primary system at all times during normal operation. They are isolated from the effect of the high-pressure primary system in normal operation by the two check valves in series. The accumulators are each of 50m3capacities filled with borated water (16 g/kg) and are maintained at around 55◦C by specially provided electric heaters. The accumulators are Nitrogen pressurized to 5.89MPa. During the injection as the accumulator level goes below a preset level the quick acting isolating valves isolate the accumulators, so that the nitrogen ingress into the reactor coolant system will be avoided.



(iii) Low-pressure accumulator injection.

This additional system for core passive flooding is designed to supply borated

water of concentration of 16 g/kg, into the reactor core in order to remove residual heat during a LOCA accompanied with a station black out. There are eight low-pressure accumulators each of 120m3capacities and divided into four trains, each train containing two hydro-accumulators. In the upper part, these hydro accumulators are connected to cold lines of main coolant pipes through NB50 lines with installed special check valves and electrical operated gate valves. These check valves are pre-adjusted to open in case the primary circuit pressure reduces below 1.5MPa. In such cases, the pressure in the accumulator increases to the primary pressure and the injection takes place because of the hydrostatic head. The outlet from the accumulators is connected to the safety injection nozzles, which helps in injecting coolant directly to the reactor pressure chamber and reactor collection chamber. Design envisages six-step flow profiling during the tank discharge. The system design envisages decay heat removal for 24 h when the system operates together with passive heat removal system (PHRS) and for 8 h with out PHRS operation.

(iv) Low-pressure emergency injection and long term recirculation system.

The low-pressure emergency injection and long term re-circulation system is designed to remove the residual heat release from the core following an accident for an extended period of time. Additionally, it also serves as the second stage of planned cool down of the primary coolant system. The system comprises of four independent trains. Each train comprises of a heat exchanger, pump, pipes and valves. In case of a LOCA, when the reactor coolant system pressure falls below2MPa two of these trains inject borated water into both reactor upper and lower plenum and the other two trains inject into the corresponding inlet and outlet main coolant pipe-lines. This system draws borated water from the spent fuel-cooling bay (16 g/kg of borated water) through suction line and in case the 500m3of spent fuel bay water available for ECCS injection gets over the suction is automatically switched over to the containment sump. The pump has got a re-circulation loop, which is normally open, and as the flow gets established during a LOCA the recirculation line gets closed. The same trains of low-pressure emergency injection are manually operated in a closed loop during the second stage of planned cool down of the reactor coolant system.



Low-pressure hydro accumulators.

2.2. Steam generator emergency cool-down and blow-down system

The steam generator emergency cool-down and blow-down system is intended to provide residual core heat removal and reactor cool-down in emergency condition due to loss of power supply or loss of heat removal through the secondary side. Under normal operation it is also used for the blow down of the steam generator for the steam generator water purification purposes. It has four independent trains and in case of loss of power supply to the station, all the system pumps are actuated as per the sequential loading programme after restoration of the emergency power. When the steam generator pressure reaches 7.35MPa, the valves on the steam lines to heat exchanger open automatically. The re-circulation pumps pump cooled condensate back to the steam generator. The control valve in the pump discharge provides automatic maintenance of the steam generator pressure at a level of 6.67MPa. The system operates in closed loop and does not need any additional source of water.

2.3. Passive heat removal system The passive heat removal system removes the core residual heat in the event

of non-availability of the normal heat removal system on account of complete loss of normal and emergency AC power supply (station blackout condition).The system consists of four independent cooling circuits, each one connected to individual steam generator. In design of PHRS, finned tube air heat exchangers, placed outside there actor building containment, are used for rejecting core heat to the outside atmosphere. The heat exchangers are connected to the secondary side of steam generators such that the steam from the steam generators is condensed in the heat exchangers and condensate returns back to the steam generator water volume, conserving secondary side water inventory. The heat exchangers are chimney like structures located on the top of reactor building annex (RBA). Higher elevation of the



heat exchangers, relative to the steam generators, ensures a reliable natural coolant circulation in the steam/water circuit. Heat exchanger shell is in form of a rectangular housing wherein lower and upper parts are connected to air ducts. The upper air duct is in form of a chimney. The cool air enters through the lower air duct. The dampers are installed in air ducts at the heat exchanger inlet and outlet. On the tube side, heat exchangers are connected with the steam generator by means of pipelines. Under the condition of the reactor plant operation, the system is in warmed up state. The valves on steam/water path are normally open and are closed only for maintenance of heat exchangers.

Passive heat removal system (PHRS).

The dampers on the air path are kept closed through electromagnetic actuators. With loss of power supply, actuator solenoid is de-energized and gates open under the action of its own weight. Due to air heating and consequent density difference between the shell inner and outer air, air flows through the shell by natural draft and slowly design flow is established thus removing the decay heat.

2.4. Quick boron injection system

The quick boron injection system is intended to bring there actor to a safe shut down state by injection of highly concentrated boric acid solution in the event of failure of reactor protection system. The system comprises of four high concentration boron (40 g/kg) tanks, each located across each reactor coolant pump set. On sensing the failure of the reactor protection system, the solenoid valves across the tank



opens and the tank becomes part of the reactor coolant system volume. The boron solution from the tanks is flushed automatically into the reactor coolant by the primary coolant pumps.

2.5. Localizing systems 2.5.1. Containment. The reactor building (RB) has double containment. The primary containment is a pre-stressed reinforced concrete, lined with carbon steel, and sealed enclosure which houses main equipment of nuclear steam supply system (NSSS). The containment performs the following functions: • It acts as final barrier against release of radioactive fission products in the event

of an accident. • Acts as biological shielding and protects site personnel against radiation under

normal and accidental conditions. • Protects NSSS equipment against external hazards. The inner containment is made

of pre-stressed concrete with a spherical dome designed for internal pressure and temperature effects during accidents and lined on the inside with 8mm thick carbon steel sheet. The outer containment is of reinforced cement concrete (RCC). In the space between primary and secondary containment vacuum is maintained to prevent any leakage to the environment. To ensure plant safety and prevent release of radioactivity to the environment, the primary circuit is housed inside the inner containment.

2.5.2. Containment isolation system.

The containment isolation system ensures containment leak tightness in the case of an accident that is likely to cause a release of radioactive fission products from the reactor core. The purpose of containment isolation system is to maintain overall integrity of the containment by isolating the normal operating system, which penetrates there actor building. Each line that penetrates the reactor building and is a part of the RCS pressure boundary or connects directly to the containment atmosphere is provided with two isolation valves. Under accident conditions these isolation valves and dampers get closed.

2.5.3. Containment Spray System.

The containment spray system removes the heat released into the reactor containment in the case of a break in the coolant pipeline inside the containment. Through condensation of the steam produced in the case of an accident, the



containment spray system limits the temperature and pressure peaks to values at which containment integrity is assured and confines the radioactive fission products released during primary system leak, thus assuring protection of the plant environment and the population. The addition of chemicals to the spray water reduces fission product concentration (in particular iodine) in the containment atmosphere and neutralizes some of the boric acid to limit its reaction with metal surfaces and consequent hydrogen production. The spray water is drawn into each independent channel of the reactor building containment and is cooled by the residual heat removal (RHR) system heat exchangers, before entering the pump suction. The containment spray system consists of four trains and each train terminates with an open ring under the dome of the containment on which nozzles are arranged to provide most even coverage of the entire containment.

2.5.4. System of vented containment.

The system of vented containment helps in limiting the containment pressure to the design limit under condition of hypothetical accident (which have potential to exceed pressure in the containment beyond design value) by control release of steam–gas mixture in a planned manner. The system comprises of a pressure-relieving device, which bursts open at a pre determined containment pressure to relieve steam–air mixture along with radioactive products out of the containment. This steam air mixture is relieved through pipelines into a scrubber filter, which removes the radioactive products to a high level of efficiency. The filtered air is purged out through a moisture separator into the outside atmosphere.

2.5.5. Annulus passive filtering system.

The annulus passive filtering system is designed for controlled removal of steam–gas mixture from the containment annulus (secondary containment volume) and maintaining a negative pressure during a SBO condition with/without LOCA. The creation of negative pressure prevents the uncontrolled release of radioactivity to the atmosphere through the secondary containment. There are four independent trains each having four heat exchanging modules. Thermal energy of the PHRS outlet, air draught is utilized in the system for its passive operation.

2.5.6. Combustible gas control system.

The system of the hydrogen concentration control within the containment is designed to avoid the formation of the explosive mixtures inside the containment by maintaining the volumetric hydrogen concentration in the air mixture below the safe



limits, thereby protecting the containment integrity under all conditions including the design basis accidents and the beyond design basis accidents.

This is achieved by providing:

(i) Hydrogen control system and (ii) Hydrogen monitoring system.

These systems include installation of catalytic hydrogen re-combiners (at 101 locations) and monitoring units (at 54 locations) at a large number of locations inside the reactor building.

2.5.7. Core catcher.

The core catcher is meant for retention of the solid and liquid fragments of the damaged core, parts of the reactor pressure vessel, and reactor internals under a beyond design basis accident condition resulting in core melting. This prevents melt spreading beyond limits of the containment. Under highly improbable conditions of core melt and breach of the reactor pressure vessel the molten core will come to the core catcher. In the core catcher, the molten core will interact with the sacrificial materials forming an eutectic mixture and the over all temperature of the molten mass will be reduced. Special arrangement is made to spray water on the corium surface at a later phase of the accident for the crust formation for minimizing the radiological consequences. The reactor pit water around the core catcher will cool the core catcher vessel along with the corium. The sacrificial material also contains gadolinium oxide in its composition such that the molten mass will always remain sub-critical. 3. Automatic fire fighting system

Automatic fire fighting system is designed to detect fires, control equipment and valves to automatically extinguish fire using water sprinklers and transmit information to the operator. In the reactor building, the cable rooms, shafts, area of primary coolant pump oil tank and other normal operating oil systems constitute major fire hazards. The automatic fire fighting system has four independent channels (4×100%) each of which is fully capable of performing its assigned tasks. Each system consists of tank, pump and group of valves. The passive components of the system, the feed, and distribution pipes, and sprayers are common for all four channels. The water supply tanks for this system are replenished by water from the main firewater storage reservoir. In case of failure of this supply, it can be fed from critical load water supply system. Capacity of each tank is selected in such a way that its fire extinguishing capacity is 15 min for a room of maximum volume.



UNITS WHICH HAVE ACHIEVED 100% OA

THERMAL

500 MW RAMAGUNDAM UNIT – 4 & 6 TALCHER UNITS – 3, 4 & 6

SIMHADRI UNITS - 1, 2 & 3 SIPAT UNIT – 5

210 MW

VIJAYAWADA UNITS – 1, 4 & 5 MUDDANUR UNITS – 2, 3 & 4

RAICHUR UNIT - 3 METTUR UNIT – 3

TUTICORIN UNIT – 4 NORTH CHENNAI - 3

AMARKANTAK UNIT – 5

UNITS WHICH HAVE ACHIEVED PLF MORE THAN 100%

500 MW

RAMAGUNDAM UNIT - 4 & 6 SIPAT UNIT - 4 & 5

210 MW

METTUR UNIT– 3 TUTICORIN UNIT - 4



UNITS WHICH HAVE ACHIEVED PLF BETWEEN 90 & 100%

THERMAL 500 MW

RAMAGUNDAM UNIT – 5 & 7

TALCHER - 6 SIMHADRI UNITS – 1, 2 & 3

250 MW

KOTHAGUDEM UNIT - 10

210 MW

VIJAYAWADA UNITS – 1,3,4, 5 & 6

MUDDANUR UNITS – 1,2 & 4

RAICHUR UNITS – 3,4 & 7

METTUR UNIT – 2 & 4

TUTICORIN UNITS – 1, 2 & 5

NEYVELI UNITS - 5, 6 & 7

NORTH CHENNAI UNIT – 3

AMARKANTAK UNIT – 5



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20.00

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100.00

120.00

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Series1 Series2

PERFORMANCE OF BHEL THERMAL SETS IN SR (210 MW AND ABOVE) FOR THE PERIOD FROM 01/04/2011 TO 31/01/2012 COMPARED WITH THE

CORRESPONDING PERIOD IN THE PREVIOUS YEAR. ( PLF IN PERCENTAGE )

STATION 2010-11 2011-12 North Chennai 78.79 88.61

Neyveli 80.84 84.08 Raichur 61.46 69.38 Tuticorin 75.07 83.23

Ramagundam 90.00 92.68 Muddanur 79.19 87.46

Kothagudam 73.77 81.05 Vijayawada 74.74 89.46 VTPS - 7 74.29 93.51 Mettur 80.03 92.08 Talcher 86.39 80.10 Simhadri 94.33 93.01 Sipat 94.92 97.43

Amarkantak -- 93.02 Bellary-1 - 89.40

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TS tidings January 2012 - BHEL - PSSRinterweb.bhelpssr.co.in/BusinessExcellence/Technical Services... · 1 JANUARY 2012 TS TIDINGS ... manual and momentary paralleling operation was