ML20071A454

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Rev 1 to Containment Fan Cooling (CF) Sys, Draft Chapter to PRA
ML20071A454
Person / Time
Site: Indian Point, 05000000
Issue date: 04/17/1981
From:
PLG, INC. (FORMERLY PICKARD, LOWE & GARRICK, INC.)
To:
Shared Package
ML20071A408 List:
References
FOIA-82-626 PRA-810417-04, NUDOCS 8302240144
Download: ML20071A454 (26)


Text

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'Fickard, L:we ano Garrick,'Inc.- INDIAN POINT FRA REV 1 tApril 17, 1951 RFVfDEI rINDIAN POINT 3 . . - . ( :[

CONTAINFEt.T FAh CCCLING (CF) SYSTEM

.- r  !.' l' A.

SUMMARY

A.1 INTRODUCTION ,

Following a LOCA, five containment building ventilation. fan cooler units will be transferred to their-accident moce of operation and will serve to keep. containment pressure below design pressure. Three of the five units cre sufficient te perform this function ano can be used in lieu of the containment spray system.

If, as a res' ult of the LOCA, iodine is released to the containment, the charcoal ~ filter beds in each of the fan cooler units will adsorb this ,

radioactive material.

The analysis is carried out under the following conditions:

e -The safeguarcs actuation signal is present.

e Service water is available at the isolation valves for each fan ,

cooler unit.

A.2 RESULTS Failure of the containment fan cooling systen,to operate in the accident t mece following activation during a safety infection sequence has been cetermined by using generic cata which has been upcated as apclicable witn specific nistorical cata from Indian Point Unit 3.

i The expected unavailability of the fan cooler unit system (inclucing iocine removal) has been rigorously calculated for those states of electric power which. failed two or less fan cooler units. The remaining electric power states where power was unavailable to three or more fan cooler units resulted in system failure and were not analyled further.

Each state was evaluated asssuming that:

e Offsite power is.available.

e Offsite power is unavailable and the diesel generators are required to supply electrical loacs.

The results of these calculations are summarized in Tables 2 and 3.

The. analysis has revealed the following dominant contributions to system .

unavailability:

e With Power On All Buses Mean Offsite power available

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- TCV 1104 and TCV 1105 f ail to open 6.2 x 10-7.(98%)

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- TCV 1104 and TCV 1105 fail to o' pen 6.2 x 10-7 (62%)

.Three of five fan cooler units fail 3.3 x 10-7 (33%)

to start ano operate

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e Bus 6A Unavailable Offsite power available Maintenance 1.8 x 10-6 (46%)

Three of five fan cooler units fail 1.5 x 10-6 (38%)

to start and operate

~ Offsite ocwer lost Three of five fan cooler units fail 2.1 x 10-5 (75%)

to start anc operate Maintenance 6.6 x'10-6 (23%)

e Bus (2A, 3A) or SA Unavailable Offsite oower available Maintenance . 1.5 x 10-3 (53%) e Three of five fan cocier units fail 1.3 x 10-3 (46%'

to start anc operate Offsite power lost Maintenance 7.9 x 10-3 (71x)

.- Three of five fan cooler units fail 3.2 x 10-3 (29%)

to start and operate A.3 CONCLUSIONS Each fan cooler unit is tranferred to the accident mode of operation by the safety injection signal which initiates internal damper repositioning and the starting of any standby units. Four fan coolers are normally in operation and this serves to minimize system unavailability in that four of the five fan coolers are not requirec to start but only to shift to the acciJent mode of cperation. Following an interruption of power to the 480 essential switchgear buses, the f an coolers are reenergized by the safeguards sequencers. System unavailability is increased in that the coolers must now successfully start and transfer to the accicent mode.

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-The effects of maintenance cn' system unava'ilability increases cranatically when less than cpticum electric power states are censicerec. Paintenance becomes the dominant effect when two fan cooler units'are failec due to' electric power unavailability.

System una'ailability v is summarized below:

Mean Unavailability Electric Po'wer State Offsite Power Available Offsite Power lost All power 6.3 x 10-7 1.0 x 10-6 6A unavailable 13.9 x 10 2.8 x 10-5 (2A, 3A) or SA 2.8 x 10-3 1,1 x 10-2

-unavailable .

The, probability distributions associated with'each of the acove mean unavailabilities are displayed in Figure A-1 and A-2. Due to the absence of f an cooler. units in the plant' analyzed by WASH-idOO, a comparison of system unavailability was not mace.

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B. SYSTEM DESCR;FTION B.1 SYSTEM FUNCTION The primary functions of the containment fan cooling and iodine removal system are:

e To reduce the pressure in containment following a loss-of coolant accicent, or a steam line break inside containment.

e To remove fission products-from the containment atmosphere should they be releaseo in the event of a loss of coolant accicent, a

The five containment fan cooling units are used to cool the containment building atmosphere following a LOCA. The units will be transferred to their accident mode, and at least three of the five.are. required for a large LOCA if the containment spray system is inoperative (less than .

three units may be adequate in small LOCAs). Heat removed by the units

- is rejected to the ultimate heat sink via the service water system through an air-water heat exchanger. ,

B.2 SYSTEM SUCCESS CRITERIA .

Any'three of the five fan cooler units with their charcoal filter becs operating.in the accident mode are capable of removing heat, iodine particles, and water vapor from containment folicwing a LOCA.

B.3 BASIC DESCRIPTION ,

The system consists of five fan cooler units, each censisting of a motor-criven fan,. cooling coils, moisture se:aratcrs, HEPA filters, charcoal filters, dampers, and an air discnarge duct. I.he units are locatea on the 68' elevation between the containment wall and the crane wall. The moisture separators, HEPA filters, and the charcoal filter assemoly are normally isolated from the main air recirculation stream. -

In the event of an accident, part of the air flow is redirected through the filtration section of the unit (moisture separator,liEPA filters, and charcoal filter assembly) to remove volatile iodine. Duct work distributes the exhaust air to a discharge heacer common to all fan cooler units during all modeslof operation. Figure 1 shows a simplified drawing of a fan cooler unit. The cooling water for all five fan cooling units during both normal and accident conditions is supplied by the essential service water system as illustrated in Figure 2.

I Each fan cooling unit is provided with four dampers and a blow-in door During normal operation, air flow enters through campers "A" (26600CFM), '

"B" (27600CFM), and "C" (15800CFM). It is then drawn through the cooling coils into the fan suction. The fan exhausts 70,000 CFM of cooled air into a 64" header common to all fan cooler units where it is distributed to various locations throughout the containment. Four fan s

cooler units are normally operated in this moae to control containment humidity and temperature.

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'In.the eventLof_a safety injecticn.actuaticn signal, damcer "D" "C" then mcVes to a blcw-in cocr_ open; caccers ",p" arc "St snut._. Damper

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prese,t pcsition whicn results in an_ airflow of-8,000'CFM entering at the bicw-in coor.and' passing thrcush theLcharccal becs anc 26,000 CFM entering the-fan cooler. unit through'oamper "C" bypassing the filtration section. The combined, flow ~then passes throuch the coolino coils ano

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exits as.previously described. Any nonoperating fan' cooler is Control automatically started and aligned to this LOCA configuration.

switches and indicating lights necessary for manual damper control are .

provided on the supervisory panel (SEF-2).

Redundant electrically operated _three-way solenoid valves are used with the dampers ano blow-in.coor to control the. instrument air supply for the air control cylinders. Upon manual or automatic actuation of the

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L, safety injection-safeguards sequence, the dampers and door'are tripped to accident positions.

Damper "A" is mounted vertically on the side of-each unit and is'open The damper will fail '

during normal conditions and closed during a LOCA.

closed by a weighted arm upon loss of electrical power _or air to the three-way solenoic. A limit switch provioes damper position indication to the control room.

Damper "B" is identical to damper "A" except that its physical pneumatic control dimensions are slightly different. Damper "A" and "B" is by a common solenoid valve and common control switches and indicating lights in the control room.

Damper "C" is mounted vertically and is throttled open during normal Pneumatic control is ,

operation and full open during LOCA conoitions.

provicec by a solenoid valve for each unit anc in the event'of loss of power or air, damper "C" is positioned:to its accicent ccnfiguration by.

Control switches and . indicating lights are provided in a weighted arm.

the control room.

Damper "0" is mounted vertically between the filtration section and the The camper is closed cooling ceil compartment of the fan cooler unit.

during normal operation and serves to isolate the filtration unit from the recirculation ~ air flow. In the event of a LOCA conoition, The damper "D" is opened to initiate flow through the charcoal beds.

  • damper will fail open by a weighted arm withower assistance or air tofrom offset the three-way
blades in the event of loss of electrical solenoid.

The blow-in door The is mounted door.is held.intoon the inlet position by sioe of thelatches magnetic filtration and is assembly.

designed to open either by an external overpressure of 0.5 A limit switch psi, and/orse is positioned

' by a pneumatic air cylinder pull cable.The blow-in door and camper "D" -

that door opening will be detectable.

for each f an cooler have a common pneumatic control solenoid, control switch, and indicating light.

5 1064A041281/1 .

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The moisture separators'are tesignec"to protect tne HEPA filters from

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cifferential pressure cue to water buildup following'a loss of ccclant accicent.- The moisture-separator. elements are of fire-resistant construction, and consist of mats of stainless steel wire mesh with a small amount of fiberglass.. The high eff.iciency particulate air (HEPA)

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filters.are. capable of 99.97% removal'for 0.3 micron particles at the post-accicent-design conditions._ The filter mecia.'is made of glass fiber and can withstand the accident ambient' steam / air temperature-conditions and 100% relative humidity. ,

The charcoal 1 filter for each fan cooler unit consists of 12 cells in a 2-1/2 foot wide by 8-foot high array. The mounting rack arrangement permits removal-of individual cells from the upstream side of the plenum. The. elements are sealed'so that air flow;cannot bypass the filters. The design flow rate through the charcoal is 8,000 CFM and is only initiated during LOCA conditions. The charcoal is designed to remove both elemental (1-131) and organic iodine,(CH3 I) and is 90% ,

and 5% efficient, respectively, in iodine type removal. The elemental

. iodine'is removed as the' mixture flows into the multitude of submicroscopic poresLand is absorbec on the internal surfa,ces. To remove organic iodine,~ the charcoal is- impregnateo with a stable form of iocine 127. By simple mechanical interchange, the organic' iodine molecules substitute for the stable I-127 contained in the charcoal ano '

the filtered gas emerges less radioactive.

Charcoal efficiency can be reduced by water-logging or exposure to-temperatures high enough to cause accelerated oxidaticn of the charccal grain surface. To protect against these conditions, incividual charcoal '4 cells and sample pieces of charcoal are removeo periodically and testec .

for their effectiveness in iodine removal. The banks are further fitted With temperature sensing elements to provice warning cf acnormal temperature conditions.

Capability for detecting and alarming the presence of fires and 1.ocalized hot spots in the. carbon filters is provided by a system of temperature switches uniformly distributed in the charcoal beds.- The temperature switches are set to.close at 4000F (which is s~ignificantly below the carbon ignition temoerature of 6800F) and are wired in parallel to a common alarm for each fan cooler unit on the safety injection supervisory panel in the control room. The closing of a single switch will actuate the alarm to indicate a high temperature condition in the filter plenum.

Upon a signal of high temperature, the control room operator initiates the water dousing system provided with each charcoal filter plenum.

This system is designed to crench the absorbers thoroughly in the extremely unlikely event of a carbon. fire during the post-accident .

recovery. Water is obtained from the mai,n headers of the containment spray system.

The portion of a fan cooler unit normally operating consists of the-motor and f an, motor cooler, and air flow cooling coils.

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,The air flow cooling coil assembly consists of_eignt coil units mounted in two banks of four coils high. These ~ banks are locatec one beninc tne and the tubes of the coil are

other for horizontal series air flow,An air-to-water heat exchanger is horizontal with vertical fins. Air-connected to the motor to form an entirely enclosed cooling system.

movement is through the 5 eat exchanger and is returned to the motor.

Both of-the above heat exchangers are supplied by the service water 1

system.

When the safeguards signal is actuated,-two normally closed valves (TCV-1104, TCV-1105) fully open and bypass service water flow around the normal temperature control Bothvalveof(TCV 1103) these on fail valves the open common on

.l discharge line from the five-units. loss of air,,and either valve is control of the two valves is providedPosition by an open-close indication switch on the lights from the mm On 58-1 safeguards panel in the CCRlimit switches on the valves ar

<<- the occasion that flow was not up to the recuirements for accident

'$ conditions, the alarm "C8 Vent Fan Cooling Water (This. Low alarm, Flow, 2,000" however, is on -

safeguards panel 58-2 would annunciate.normally out of ser The drainage from the cooling coils, moisture separators, charcoal dousing and the motor heat exchangers is collecte Using this device, the flow rate of the V-notch-(triangular) weir. After passing over the V-notch weir, the water can be calculated.

drains empty into the containment sump which is small in surface area and minimizes the amount of reevaporation.

.C If the' drainage rate for all five units' is nearly the same, it may be concluded atmosphere.

that this water is concensate from the conta the other units, however, is indicative of a leak. in one of the cooling coils. The leak rate of this service water could then be estimatec a

. the difference between the flow from the particular fan unit and theThe c average ~ flow through the other four V-notch weirs.ea The fans are centrifugal-type and deliver 34,000 The CFM at accident motors have

- conditions and' 70,000 CFM at normal contiitions.

"Stop-Auto-Start" switches with indicating lights on the 58-2 safegua Fan contrcl is also possible from a local control panel in the CCR. (Should control panel on the 15-foot elevation of the control buildin safeguards panel would ~ annunciate.)

The motors are 225 HP, 720 rpm direct drive and The are supply self-contained and a fitted with heat exchangers cooled by service water.

discharge service water are common w1th the service water supp discharge of each unit's cooling coils. heat exchanger is which allows adjustment of motor operating temperature.

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Both the fan and motor are fitted with. vibration detectors. Each cetector is resettable below the' alarm setooint by a c mmon button on the-58-2 safeguares panel in the CCR. Should vibratio' levels reacn the alarm level (initially this setpoint will be .49 above the normal zero setting for the Vibraswitch with the motor operating at normal conditions), an alarm on the 58-1 safeguards panel ~(" Control Recirculation Fan Motor Bearing Vibration") is annunciated. At the same time, one of the.five indivicual alarm lights will illuminate on the SB-2 safeguards panel (next to the reset button).

Fan bearing temperature is also monitored. Both the inner and outer bearing temperatures for all five fans are indicated on the bearing

-monitor safeguards panel (SK). Should either reach a temperature of 1900F, an alarm " bearing monitor" on the SE safeguarcs panel would annunciate and particular information 'as to which bearing is hot woulo be proviced by the readout of the bearing monitor. Overload protection for the fan motors is provided at the switchgear by overcurrent trip devices in the motor feeder breakers. The breakers can be operated from the CCR or from the local panel on the 15-fcot elevation of the control

'builoing. This will allow for fan manipulations if necessary.

Located just upstream of each fan cooler unit is a temperature detector ard a humioity detector. The humidity detector is a dynalog electronic-type element which uses a-coil of gold wire tnat will vary in electrical resistance as a function of the moisture content of the '

containment atmosphere. The information provioed by this element anc the temperature detector is used to determine the dew point in containment. This information provices an excellent indication of .

leakage from either the primary or secondary systems, into the c containment.

S.4 INTERFACING SYSTEMS The fan cooler units interface with the following systems:

e Electrical Power e Service Water e Safeguarcs Actuation System-Electric power is supp' lied from the buses noted below:

e Motor 31 Bus SA e Motor 32 Bus 2A e Motor 33 Bus SA

-o Motor 34 Bus 3A e Motor 35 Bus 6A B.5 TECHNICAL SPECIFICATIONS .

'- The reactor is not made critical unless all five fan cooler and charcoal filter units are entirely operable. During operation one fan cooler unit may be out of service for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> (coolers 32, 34, 35) or 7 days

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L (ccolers 31 or 33) witnout. necessitating a shutacwn to the hot stancby-conciticn proviced both centainment spray cumps are checked operaoie cai,1y. Fan cooler unit failCres must be corrected within the specifiec

-periods or the reactor is placed in.the hot shutdown condition using; normal operating procedures. If the recuirements are not satisfied within an additional 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />, the reactor is placeo in the cold

. shutdown condition.. .

B.6 TEST AND MAINTENANCE Corrective maintenance is only performed on the units when a failure

. occurs. Periodic maintenace is performec on a scheculed frequency.

Periodic surveillance tests _are performed on the accident dampers and the fan cooler motors to test' damper switching anc operation. ' Tests are performed both monthly and quarterly during unit operation. The units are run in the accident mode for about 15 minutes per month. Operation is from the control room. Since the tests place the system in the accident mode, there is no adverse effect on system availability. '

Additional, more detailed, testing of the dampers is conducted during each refueling.

Visual inspection of the filter installation is performed every refueling, or at any time work on the filters could alter their integrity. Measurement of the pressure drop across the moisture separators and HEPA filters is performed at each refueling. The HEPA filter banks are tes'ted with locally generated 00P (dioctylphthalate

- particles test) at each refueling.

Periodic in-place testing of the filtration assemblies is made by injection of a~ freon aerosol in the air stream at tne filter inlet to q verify the leaktightness of individual filter elements and their frame seals.

The iodine removal efficiency of at least one charcoal filter charcoal coupon (samples) from each unit is tested at every refueling. If the filter test fails, the charcoal in that unit is replaced.

d B.7 OPERATOR INTERACTION Because the fan ~ cooler units operate more or less continuously,in the normal mode, and there is no testing except curing the annual outage, there is very little cause for human action and, therefore, little chance for human error. During accident conditions, the fan coolers are switched automatically to the accident mode. Failure of the automatic start system can be compensatea for by operator action. There are sufficient inoicators on alarms such that the operator would be immediately aware that the units had not swittnec to the accicent moce and, therefore, he would start the units manually. A human error of this kind should, consequently, be low.

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5.5L CGVYCri CAUSE EF.=ECTS It is conceivable that:the operation of all five fan cooler units could be-.effectec by an. occurrence which~ simultaneously results in the plugging of the charcoal filter beds with airborne debris or the' cooling

' coil- tubes with material entrained .irf the service water'supRly.. Due to lthe rigid cleanliness requirements'in containment and.the straining of-

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the service water source, it is felt that these modes of failure are of.

little significance anc tan be.discountsd when-coi' pared with system-

' unavailability due.to ha cware and maintenance.

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C. LOGIC MODEL C.l. TOP EVENT

.The-top undesired events for cooling and iodine removal are derived from the primary functions of the system, and are:

e. Failure to circulate containment atmosphere and maintain containment pressure below maximum design pressure.

e Insufficient iodine removal by charcoal filters.

C.2 SYSTEM FAULT TREE

>- The f ault trees used to analyze the accident operation of the containment f an cooling (CF) are shown in Figure 3. ' Only haroware failure events are modeled; other causes are accounted for during the quantitative analysis in Section D. The SI actuation signal is recuired to initiate fan cooler operation and to shift the air ficw dampers and service water valves while electric power is reouireo for fan operation. Both are modeled.as house events.

During normal operation four fan coolers'are utilized to maintain containment humidity and temperature. .In the event that the accident-mode of operation is reouired the scenario of system response is ,

cependent upon the availability of power at the 480V essential switchgear buses.

When the continuity of power is maintained to the,a80V essential 9 switchrear. buses, the safety injection signal starts the noneperating fan cooler unit and shifts tne camcers.in all five urits to the acticent positions.

Should the normal. source of power be interrupted to the fan cooler units, all five units must then start and shif t to the accident mode ,

when the diesel generators restore electrical power.

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D. CUANTIFICATION O.1 RAN00M HAR0kARE FAILURES Hardware failures in the fan cooling system can be attributed to either a failure in the fan cooling unit itself_ or an interruption of the service water supply to one of the heat exchangers contained in the cooling unit. Figure 4 outlines components which must function to yield system success. -Supercomponent A requires the operation of three of the five cooling units for twenty-four hours. Supercomponent B displays the reouirement that one of the two temperature control valve bypass valves opens in the common service water oischarge from the five-cooling units.

The unavailability'of a single operating fan cooler to shift and operate in the accident mode can be calculatec as follows:

Mean Failure (0)/d Cocoonent Failure Mode Ouantity from Table B.2-2 Fan Cooler Fails to shift 1 9.79 x 10-6 anc run .

Iso MOVs Closes (Mech- 3 9.15 x 10-8 .

anically during operation)- .

Heat Exchangers Rupture 2 9.73 x 10-7 Fan Coolers Fails to Start 1 7.80 x 10 4 q

on Demand O = 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> IO + 30 y + 20 HE HC C O ( run )

This yielos a Mean: 2.9 x 10-4 Variance: 1.2 x .10-7 Should power be interrupted, the above expression is modified to reflect the subsecuent starting of the fan cooler unit curing sequencing.

OHC = Oc +[1-0 C hO HC s start ( start / 0 This results in a ,

Mean: 1.1 x 10-3 Variance: 2.3 x 10-6,

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ne narcaare unavailacility cf supercomponent A (three or more fan ccoler units fail) witn all lEOV essential switchgear buses enercizeo is

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tne su: cf the unavailabilities for the 16 possible combinations where three'or more fan coolers are inoperative. With no eiectrical power interruption, the unavailability of supercomponent A is dependent t.pon the shif ting.to the accident mode of four norm 6'ly operating units anc the starting and shifting of the stan'dby unit. -

O HA =.6 f0 HC O HC + 4 [0HC + 4 [0HC [0HC( + [0HC -

(0/ \S/ (0/ ( 0/ \S/ ( 0/

  • hHC HC 1

.( 0 / iS/

With an electrical power interruption, the unavailability of ,

.supercomponent A is dependent upon the successful starting and shifting to the accioent moce of all five fan cooler units.

+

O gg

=MhHC . - 5 [0HC O HC (S/ (5/ (5/

The results of the above calculations are summarizec in Tables 2 and 3.

For the remaining states of electric power considerec, the calculation is alterec in that a recucec number of harcware f ailures are recuirec to fail supercomponent A. S

. With power unavailable at bus 6A, anc the continuity cf power maintaineo at all other buses, the-expression for the unavailability of supercomponent A becomes:

Ogg = .2 + 4 l0gcf + /O HC + .8

'6l0HC 3 [0

( 0j (0) (0/ . . ( .HC 0/

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+3/Oh[N\+3[0 HC (S/

HC HC (0/

[0HC (S)

+ [0 HC (0/

+ [0HC [OHC

( / \S/

, (0/

The first term represents the situation where the ccoler rendered inoperative by the bus unavailability (6A) is also the stancby cooler, while, tne second term describes the situation where the loss of the bus

- fails one of the four normally operating fan coolers.

'n' hen'the Continuity of power is not maintained with power unavailable at bus 6A, the harcware unavailability of superccmponent A is:

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+4 O gg

=6hHC O

hC ' hhc

-( 5 / ( 54 45/

- With power unavailable to either 2A and 3A or SA, supercomponent A-is -

reducec to three cooler units and any single failure will rencer the-system failed. In this case,-the hardware unavailability of sucercomponent A with electrical power continuity is:

Ogg = .4 + .6 2

' 3 [0HC OHCb + [0 HC (0/, ,

(0) ( S),

The sicnificance of the terms in the equation is identical to that in the bus 6A unavailable condition.

When the continuity of power is not maintai'ned the hardware unavailability of supercomponent A becomes:

O

  • HA hMC\

(5/ .

The unavailability of supercomponent B is unaffected by electric power.

- state and is cetermined by squaring the mean unavailability of each of the air-operated temperature control valves to open on demand (TCV Mean = 4.c5 x 10 4--Table B.2-2).

Total sys' tem unavailability resulting from harcware failure (Og system) for each electric power state ano is the sum of'those ceterminec for supercomponents A and B. -The.results are containec in Tables 2 anc 3.

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0.1.1 TEST The fan cooler units are in operation in their normal mode whenever the plant is operating. Testing is either done during the annual refueling or by running the units for short perioos in.the accicent mode.

Therefore, there is no testing impact on system unavailability.

D.1.2 MAINTENANCE Indian Point 3 maintenance experience yields a fan cooler unit unavailability (OCM) Of:

Mean: 5.2 x 10 8

. Variance: 4.5 x 10-8 Maintenance is only performed on the units when a f ailure occurs anc

- only one fan cooler may be out of service during normal operation without necessitating a unit shutdown. With electric power available to all buses, system unavailability due to maintenance (05g) results 14 106aA041281/1

k wnen, with cne ccoler securec for. maintenance, two accitional fan cccling units teccme incperative as a result of harcoare failures. This situation is represented by:

05g = 5(0CMI -

6[0HCb + 4[0HC' * [0 HC i0/ (0j- (0j With electric power unavailable to one cooling unit (f ailure of bus 6A);

system unavailability cue to maintenance becomes:

0 5M = 40 CM 3O HC 3/0HCJ +/0HC (0/ (0/' (0j .

Failure of electric power to two cooler units (failure of bus SA, 2A

, or 3A) results in a system unavailability due to maintenance of:

03g = 30CM O

+ 60CM[0HChv30 CM HC -

( 0 l' (0)

A summary of the maintenance unavailabilities for each of the electric power states is contained in Tables 2 and 3. .

D.l.3 STATISTICAL

SUMMARY

Overall system unavailability is the sum of the centributions from

  • hardware (OHsystem) + maintenance (033) 'for each of"tne states of electric power analyzed. A summary of these'calculatiens is_containec in Tables 2 anc 3.

a

. t,- .

15 _

1064A041281/1 ,

f.'  :~

TABLE I .S SYSIEMS C0tf0N2NTS

    • urce Component and Normal failure Rate /d Fai M e Mode Position Mean/ Variance. h. g [

Fault Tree Code Service Water Values Failure to open Closed 4.98 - 4/ g TSW1104Q 4.03 - 7 Fa.11ure to open Closed TSW1105Q Transfers closed Open 9.15 - 8/

TSW41NC 1 Transfers closed Open 1.0 1 - 14

- TSW44NC TSW11NC Iransfers closed Open ileat Excnangers KilECL .

Rupture or gross Passive gg , y _

leakage 3*34 - 12 24

. kiter. Rupture or gross Passive leakage Fan Cooler KBL2NN Fails to start 7.80 - 4/ 22 2.56 - 6 KBL2145 Failure to switch 9.79 - 6/ 23

~to and operate -

2.23 - 10 in LOCA mode -

.A -

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IAllLC 3 SIAilSilCAL-

SUMMARY

CONfAlhMCRl"l'AN COOLED UNAVAILAlllLIFY Uf f s ite l'ower unavailabli!

Electric Power States Unavailability Of All Power Available 6A Usiavailable (2A, 3A) or SA Unavailable Supercomponent A Mean 3.3 x 10-/ 2.I x 10-5 3.2 x 10-3 liardware Failures Variance 3.0 x 10-13 2.1 x 10-/ 2.0 x 10-5 ,

(OilA)

G 6.2 x 10-7 Supercomponent 11 Mean 6.2 x 10-/ 6.2 x 10-7 liardware Failures Variance 1.6 x'10-13 1.6 x 10-31 'l.6 x 10-31 6

( (11111 )

System liardware -Mean 9.6 x 10-11 2.1 x 10-5 3.2 x 10-3 Variance 4.0 x 10-Il 2.0 x 10-8 2.0 x 10-5 (1111 system)

System Maintenance Mean 5.3 x 10-8 6.6 x 10-6 f.9 x 10-3 Variance 1.4 x 10-13 1.1 x 10-10 0.1 x 10-5

((153) ,

Total System Mean 1.0 x 10-6 2.0 x lo-S 1.1 x 10-2 Variance 3.9 x 10-11 2.0 x 10-8 9.9 x'10-b (ilsys tem) 3.6 x 10-3 Sth 3.5 x 10-9 2.0 x 10-6 Median 1.S x 10-/ 8.0-x 10-6 7./ x 10-3 95th 2.4 x 10-6 5.7 x 10-5 2.4 x 10-2 s

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SUPERCOMPONENT A

~

F AN COOLER UtilT 3 COOLER ISOLAllON P40.38 SWITCllES - VA LVE S ilE MAIN -

TO AND OPEllATES OPEN IN ACCIDENT MODE F AN COOLER UNIT 3 COOLE R ISO LATION NO 32 5WITCilES - V A LVES ilE MAIN -

TO AND OPERATES OPE N IN ACCIDENT MODE SEllVICE WATEll

- VALVETGV -

f~~7 I~~7 F AN COOLEH UNIT 3 COOLER ISOLATION J

3/5 l 740. 33 5 WIT CalES VALVESilEMAIN ELECTRIC 'I -

N t St

' $lGNAL L-- . L_ _ J POWER TO AND OPEllATES iN ^CCioENT MOoE

" V' -

SEny,CE Alti, VALVE TCV 1105 OPE NS FAN COOLER UNIT 3 COOLER ISOLAllON 6 NO. 34 5 WIT CllES _ VALVESilEMAIN -

TO AND OPEll ATES OPEta IN ACCIDENT MODE F AN COOL.ER UNIT 3 COOL E fl ISO LAllON

~

f40. 35 sWITCalES _ 94 tygs ggggggn _

TO AND OfEil ATES OPE N e IN ACCIDENI MODE ,

Figure 4. Reliability Glock Diagram of. fan Cooler System a -