ML16256A493
| ML16256A493 | |
| Person / Time | |
|---|---|
| Site: | Waterford  |
| Issue date: | 08/25/2016 |
| From: | Entergy Operations |
| To: | Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML16256A115 | List:
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| References | |
| W3F1-2016-0053 | |
| Download: ML16256A493 (59) | |
Text
WSES-FSAR-UNIT-3 10.4.9B-i Revision 307 (07/13)
(EC-33720, R307)
START OF HISTORICAL INFORMATION
APPENDIX 10.4.9B EMERGENCY FEEDWATER SYSTEM RELIABILITY ANALYSIS
EC-33720, R307)
WSES-FSAR-UNIT-3 10.4.9B-ii Revision 307 (07/13)
(EC-33720, R307)
CONTINUED HISTORICAL INFORMATION APPENDIX 10.4.9B TABLE OF CONTENTS 10.4.9B.1 Introduction
10.4.9B.2 System Definition
10.4.9B.2.1 Top Event
10.4.9B.2.2 System Boundaries
10.4.9B.2.3 Basic Events and Causes
10.4.9B.3 System Model Construction
10.4.9B.3.1 FMEA (Independent Failure Considerations)
10.4.9B.3.1.1 Component
10.4.9B.3.1.2 Component State
10.4.9B.3.1.3 Effects
10.4.9B.3.1.4 Inherent Compensation
10.4.9B.3.2 Common Cause Failure Consideration
10.4.9B.3.3 Fault Tree
10.4.9B.4 System Model Qualitative Analysis
10.4.9B.5 System Model Quantitative Analysis
10.4.9B.5.1 Event Causes and Probabilities
10.4.9B.5.1.1 Unavailability Due to Test and Maintenance
10.4.9B.5.2 System Failure Probability Analysis
10.4.9B.6 Discussion of Results
10.4.9B.7 Conclusions EC-33720, R307)
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CONTINUED HISTORICAL INFORMATION 10.4.9B.1 Introduction
This report summarizes the results of a reliability st udy for the Waterford 3 EFS required by the NRC in Reference 1. The primary purpose of this study is to assess the syst em availability to function on demand and identify any areas where changes in des ign, operating procedures and/or system testing/maintenance practice could result in significant availability improvements. The steps in this study were:
- SYSTEM DEFINITION: The objectives of the study and its scope and limit ations are clearly defined.
- SYSTEM MODEL CONSTRUCTION: A Failure M odes and Effects Analysis for each component and Common Cause Analysis are performed and used to construct a system fault tree for each condition to be analyzed.
- SYSTEM MODEL QUALITATIVE ANALYSIS: The system model is examined to determine the combination of events (minimal cut sets) wh ich can lead to system unavailability on demand.
- SYSTEM MODEL QUANTITATIVE ANALYSIS: Probab ilities of occurrence are determined for the basic events in the fault tree, and are used to ca lculate the overall system availability and to weigh the relative importance of the events and event combinations as failure contributors.
- ANALYSIS OF RESULTS: The results of the qualit ative analysis are reviewed to determine if any changes in design, operating procedures and/or syst em testing/maintenance practice could result in significant availability improvements.
The details of the actual study are described herein.
10.4.9B.2 System Definition
10.4.9B.2.1 Top Event
The purpose of the analysis is to determine the avail ability of the EFS to maintain the Reactor Coolant System in the hot standby condition on a demand pr oduced by a Loss of Main Feedwater (LMFW), LMFW with Loss of Offsite Power (LOOP), and LMFW wi th Station Blackout (SB). Operation under main steam or feedwater line break or LO CA conditions were not considered.
The EFS flow requirement for each condition is described below:
LMFW: It is assumed that the operator will tr ip the Reactor Coolant Pumps (RCPS) 30 minutes after the reactor trip brought on by the LMFW, if only one motor driven EFW pump is available for operating.
This is a required operating procedure action intended to reduce the heat load on the primary system. EC-33720, R307)
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CONTINUED HISTORICAL INFORMATION If both steam generators (SGs) are ava ilable, 450 gpm of EFS flow (225 per SG)* is needed to maintain the level required for the SGs to be adequate heat
sinks. If only one SG is available, 400 gpm to that SG is adequate to maintain
the level required for the SG to be an adequate heat sink (required EFS flow
when one SG is available is less than for two SGs because of the RCS energy
dissipated as the unfed SG boils away its inventory). To simplify the system logic model, it will be assumed that 450 gpm EFS flow, either split between two
SGs or all delivered to one SG, is required for the LMFW condition.
LMFW & LOOP: The EFW flow requirement for this condition is less than for the LMFW condition, since the RCPs will stop immediately upon t he LOOP. However, to simplify the logic model, the same EFS flow requirement for the LMFW (450 gpm) is
conservatively used for this case as well.
LMFW & SB Same as LMFW & LOOP.
Thus, it is conservatively assumed t hat the EFS minimum function (i.e., to deliver a total of at least 450 gpm to the steam generator(s)), and therefore the top event, is the same for all three c onditions regardless of the number of SGs available.
It is known that the basic failure events to be cons idered have small probabilities. Thus, to minimize round-off error in numerical calculations, the system model will be constructed in fault tree as opposed to success tree fashion. The top event will then be failure to deliver at least 450 gpm EFS flow to the steam generator(s), or "< 450 gpm EFS flow to SG's."
The scope of the top event spans only the availability of the system to start on demand for the transients under consideration and does not include the reliability of the system to carry out this mission through the required duration (several hours), cons istent with the NRC request in Refer ence 1. However, it is believed that for the events analyzed, t he system undependability is dominated by the unavailability to start on demand.
10.4.9B.2.2 System Boundaries
The EFS simplified flow diagram is shown on Figure 10.
4.9B-1. For this analysis, the system consists of the EFS flow path from the Condensate Storage Pool (C SP) to the normal flow c onnections with the Main Feedwater System (MFWS), inclusive of in terconnections with other systems. Support systems/components considered in the analysis not shown on the figure are pump and valve control circuits, power supplies and ESFAS logic. More deta il on the types of failures considered is given in Subsection 10.4.9B.2.3.
__________________
- It should be noted that this is not in consistent with the conservative licensing design basis EFS flow rate of 575 gpm. The analytical bases for the 575 gpm flow requirement contain conservatisms which are not appropriate for a realistic reliability study.
EC-33720, R307)
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CONTINUED HISTORICAL INFORMATION 10.4.9B.2.3 Basic Events Considered
The types of events considered in the FMEA and t heir possible causes are listed by component as follows. It should be noted that in some cases events which obviously were not failure events were not fully developed in the FMEA. Also, not all the possible causes listed under each component type are applicable to each event for the component. This A ppendix is a stand-alone study. The following is in addition to the study and is included for clarification purposes:
In performing the system reliability study contained in this Appendix, the failure of check valves to operate properly was evaluated. However, failures of c heck valves EFW 2191A, B are not considered credible failures.
MANUAL VALVE
- Events:
Open (able to pass flow)
Closed (unable to pass flow)
- Possible Causes:
Plugging (flow path blocked)
In wrong position due to test or maint enance on another component at the time of demand Normal or proper position
CHECK-VALVE
- Events:
Open against forward current Open against reverse current Closed against forward current Closed against reverse current
- Possible Causes:
Frozen in wrong position due to mechanical binding In test or maintenance Proper position EC-33720, R307)
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CONTINUED HISTORICAL INFORMATION POWER OPERATED VALVE
- Events:
Remains OPEN on demand close signal Remains CLOSED on demand open signal CLOSED and receives no automatic signal OPEN and receives no automatic signal
- Possible Causes:
Mechanical binding Control circuit failure Actuating signal failure Motive force failure Left in wrong position (if valves rece ives no confirmatory automatic signal) after test or maintenance action In test or maintenance
PUMP Events:
Fails to deliver the required flow
Possible Causes:
Mechanical binding Control circuit failure Actuating signal failure Motive force failure
ACTUATING LOGIC
Events: Signal not generated when required
Possible Causes:
Unspecified electronics failure In test or maintenance EC-33720, R307)
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CONTINUED HISTORICAL INFORMATION 4 kV POWER SUPPLY (DG's)
Events:
Does not supply power Possible Causes:
DG failure to start DG in test or maintenance
The following events were not considered:
Passive fluid boundary failures or valve disc-stem separations.
Spurious control circuit or actuation circuit logic commands.
Common cause failures considered as basic events are discussed in Subsection 10.4.9B.3.2. Common cause failures not considered were sabotage or those of a physical layout nature, such as non-seismic systems falling on EFS components, high energy line brea ks in other systems affe cting the EFS, etc.
This is not to say that such possibilities exist in t he Waterford 3 design; it was simply not within the scope of this study to investigate this.
10.4.9B.3 System Model Construction
10.4.9B.3.1 Failure Modes and Effects Analysis
A Failure Modes and Effects Analysis (FMEA) wa s developed as a first step in the system model construction to identify the effects that indivi dual component actions have on subsystem and overall system operation. The FMEA describes the effect on the system of every component action regardless of whether or not the action contri buted to system failure, and is a necessary complement to the fault tree for this reason.
The system was broken up into the functional bl ocks (shown by the dashed lines and roman numerals on Figure 10.4.9B-1) for generation of the FMEA, with the breakdown for these blocks chosen with an eye towards facilitating construction of the fault tree.
The structure and rationale behind the details of the FMEA is discussed below. The FMEA is given in Table 10.4.9B-2.
10.4.9B.3.1.1 Component
Each component selected in accordance with the crit eria of Subsections 10.4.9B.2.2 and 10.4.9B.2.3 appears in the FMEA, with the except ion of vent and drain valves. These were not included because the system is kept continually full of water by the CSP/MFWS, so it is not considered credible that a vent or drain valve could be left open without being quickly noticed and corrected.
For simplicity in this study, each component consider ed was assigned to a two digit identification (ID) number. A list of all components considered, along with a description of the component, it's two digit ID number, actual ID number and FMEA blocks in wh ich it appears is given in Table 10.4.9B-1.
10.4.9B.3.1.2 Component State
Each component was considered in it's extreme states within the limitations of Subsection 10.4.9B.2.3 for the purpose of analyzing it's effects. For exampl e, valves were considered in both the open and closed EC-33720, R307)
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CONTINUED HISTORICAL INFORMATION state. Actuation signals were analyzed only for failure to be generated when required, but not for spurious generation.
10.4.9B.3.1.3 Effect
The effect of the component being in the state under study on the functional block, of which it is a part, is analyzed. The following general guidelines were used in analyzing the effect of the component states:
a) Valves: can impair system operation in the closed position by blocking flow where flow is desired, or in the open position by diverting flow or permitting flow where not desirable.
b) Pumps: can impair system operation by not pumping fluid as required and by providing a possible flow diversion path for parallel pumps.
c) Valve/Pump Control Circuits: can cause a pump not to start or valve to not change position when required, leading to the same system impairments discussed under Pump and Valves above.
d) Actuating Logic: can fail to issue a comm and to the pump or valve control circuits, leading to the same system impairments discussed above.
e) Power Supplies: can fail to provide motive force to pumps or valves, leading to the same system impairm ents discussed above.
10.4.9B.3.1.4 Inherent Compensation
Any inherent provisions in the system which compensate for the degradat ion brought about by the component state under study is listed to a ssist in the fault tree construction.
10.4.9B.3.2 Common Cause Failure Consideration
Several events were assessed for their potential to induce common cause failures in the EFS, as discussed below.
a) LOSS OF INSTRUMENT AIR: All air-operated valv es in the EFS require instrument air to go away from their operational state (i.e., to cl ose). A loss of instrument air would have no immediate effect on the system as the valves have air accumulators sized for several open-close cycles, but would prevent the operator from reclosing the air operated valves once the accumulators are exhausted. This has no adverse affect on system operation for the transients under consideration.
b) LOSS OF COMPONENT COOLING WATER: T he EFS does not rely on Component Cooling Water. The EFS pumps, unlike the ECCS pumps, handl e a relatively cool fluid which is itself sufficient for pump cooling, so no CCW is required.
c) LOSS OF AC POWER: The EFS Turbine Driv en Pump (TDP) and all power operated valves associated with its flow and steam supply paths , are independent of ac power except normally open, fail as is, Valve 74 (Turbine Trip and Th rottle Valve), whose operation (closure) is equipment protective and not required for system functioning. No TDP auxiliary functions, including lubrication, are dependent upon ac power.
EC-33720, R307)
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CONTINUED HISTORICAL INFORMATION Extended operation of the TDP is indirectly reliant on ac power by the ventilation system serving the pump cubicl
- e. Without ventilation for several hours when the pump is running, temperature in the pump area would become high enough to affect the pump controls, possibly in an adverse manner. This would not be an immediate failure however, and time would be available to restore some ac power. As such, this failure mechanism was not factored into the fault tree.
d) POOR WATER QUALITY CONTROL: If very lo w quality water were used for extended periods in the EFS, it could conceivably cause corro sion/ particle deposition in the system, perhaps binding the moving parts of the pumps and valves.
However, it is not credible that this would occur to any extent in the EFS for the following reasons:
- 1) Only condensate or demineralized quality water is used in the EFS. (EC-34060, R306)
- 2) The system is periodically treated with a pH control agent and Hydrazine as necessary to control water chemistry. (EC-34060, R306)
- 3) The system is periodically flow test ed, which not only provides some system flushing, but assures that water quality has not affected the pumps.
- 4) The valves are periodically stroke tested, which would detect any loss of function due to corrosion or particle deposition.
e) TESTING: As discussed in Subsection 10.
4.9B.5.1.1, system testing has no potential for causing common mode failures.
f) MAINTENANCE: As discussed in Subs ection 10.4.9B.5.1.1, only one maintenance operation (Condensate and Feedwater Systems Pre-Startup Cleaning) has potential for causing a system common mode failure. This has been added to the fault tree as common cause failure basic event ME1.
g) CONDENSATE STORAGE POOL PROBLEMS: The C SP is the only dedicated source of water to the EFS, so it is assessed for it's potential to cause EFS failure.
- 1) Tank Vent Clogging: The CSP (essent ially a stainless steel lined concrete room) is equipped with an 8 in. Schedule 40 (nominal wall thickness = 3/8 in.) vent line
which penetrates the pool ceiling and terminates in the above room (CCW pump cubicle) six feet above the floor.
There is no isolation valve on the li ne, and there is no known sources of debris in the area which could clog such a lar ge diameter pipe. Also, the pipe ends with a "U"-bend, with the open end turned downwards.
Accidental crimping of the thick walled pipe is not considered credible since the pipe is not within the travel path of any cranes, and is located in a congested area behind an inst rument cabinet, out of the path of any fork lifts. As such, failure of the pool due to a restricted vent line is not considered credible. (DRN M 9900828, R11) 2) Low Tank Level: The CSP is used mainly as a water supply for the EFS. The only exception is its use as a makeup source for CCW makeup, which places a minimal demand on the pool. The pool is equipped with redundant, safety grade level indicators
and the operators are required to verify that t ank level is within allowable limits every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. As such, it is not considered credible that tank level would be out of limits when a system demand occurred. (DRN M 9900828, R11
- EC-33720, R307)
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CONTINUED HISTORICAL INFORMATION
- 3) Pump Suction Flashing: The CSP water re mains at RAB ambient temperatures, usually below 90 F. There are no lines from hot, interf acing system which connect to the lines between the CSP and pump suction, as in some other plants. Thus, flashing of the pump suction source is not considered a cr edible common cause failure mechanism.
10.4.9B.3.3 Fault Tree
The fault tree was constructed from the FM EA (independent failure analysis) and the common cause failure analysis, using the same functional blocks as in the FMEA. The failures and combinations of failures that could defeat operation of the functional block (including failures from other blocks) were combined using conventional AND and OR gates.
Then the blocks were arranged through logic which related them to the "top event" specified in Subs ection 10.4.9B.2.1. The last step was particularly complex for the EFS due to its extensive interconnec tion of redundant trains and the multiple ways in which it can successfully perform its function.
To simplify the fault tree, only the (failure contri buting component states (or events) from the FMEA, and not all possible causes of the state were incorporated into the fault tree. For example, if a valve being closed (unable to pass fluid) was a contributor in the fault tree, "VALVE XX CLOSED" was included as the event in the fault tree rather than placing an OR gate in the tree with event inputs such as "VALVE XX CLOSED DUE TO MAINT", "VALVE XX CLOSED DUE TO ERROR", "VALVE XX PLUGGED WITH DEBRIS," etc. The latter would generate an unmanageable number of cut sets, and would produce a computer analysis output which fo cused on causes of concern as opposed to component of concern, which is more useful. A complete listing of t he causes and probabilities of each event along with the rationale for their selection is given in Subsection 10.4.9B.5.1.
The fault tree was not constructed to take advantage of "fortuitous failures," e.g , where a failed or misoperated components negates the effect of another failure or misoperation. This does result in some physically unrealistic failure combinations, but constr ucting the fault tree to eliminate them would unduly complicate the fault tree without significant improvement in predicted system reliability.
As noted in the FMEA, certain components can contribut e to system failure by being in one state (e.g., valve open) under certain conditions and by being in the opposite state (valve closed) under different conditions. The fault tree could have been constructed to prevent t he possible generation of cut sets including such mutually exclusive conditions by us ing NOT and AND gate combinations. However, this could not be done because the computer program used in the fault tree analysis will not accept a NOT gate, so such cases were handled by manually culling t he cut sets of such combinations, as discussed in Subsection 10.4.9B.4.
Any failure which could affect more than one component, including common mode failures, were factored
into the fault tree at the level at which the effect is seen, as opposed to being factored in a failure mode to each individual component. For example, the EFAS1 "A" logic failure, which could incapacitate both SG1 flow paths by not opening a valve on each path, was not entered as a failure to each valve individually, but rather was entered in an OR gate along with other events/event comb inations which would incapacitate both SG1 flow paths. This approach was used because it permits use of the fault tree as a visual tool to readily identify the syst em level effects of certain failures.
EC-33720, R307)
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CONTINUED HISTORICAL INFORMATION A single fault tree including all components considered in the study was first generated. This fault tree represented the system under CASE 2 - LMFW/LOOP, and is shown on Figure 10.4.9B-3. For the other cases, the CASE 2 fault tree was reviewed to elimi nate components which could not play a role due to differing initial condition assumptions. The result ant CASE 1 - LMFW and CASE 3 - LMFW/SB fault trees are shown respectively on Fi gures 10.4.9B-2 and 10.4.9B-4.
It was assumed that the operator did not correct com ponent failures with one exception. The operator is assumed to be available to back up the automatic actuation of the system. This is considered reasonable, because the operating guidelines for plant transients call for the operator to confirm emergency feedwater actuation (immediately after confir ming reactor trip), and to take action to restore emergency feedwater if it is not f unctioning. Both system and component level controls are available to the operator in the main control room. Failure of the operator to back up syst em level actuation signals has been factored into the fault tree as event OEI.
10.4.9B.4 System Model Qualitative Analysis
The purpose of the system qualitative analysis is to determine the "minimal cut sets," or minimum combinations of events which can l ead to the top event. Since it was expected that most of the failure events were of relatively low probability (10 or le ss), it was decided that only the minimal cut sets containing three or less events would be of interes
- t. Events containing more than three events would be of such low probability that it would not be meaningful to pursue them.
The PREP Code was chosen to perform the qualitativ e analysis because its combinational (trial and error) method of fault tree analysis is generally effici ent when three event minimal cut sets are desired.
Each fault tree was individually analyzed to determine it s three-or-less event minimal cut sets. The cut sets for each case are listed on Tables 10.4.9B-3 through 10-4.9B-5.
As discussed in Subsection 10.4.9B.3.3 some component s (check valves 34, 35 & 36) enter the fault tree twice, in different states. Since the computer l ogic model could not be constructed to eliminate the possible generation of cut sets containing the same co mponent in two different states, the output of the PREP Code was manually culled to find and eliminate such cut sets.
10.4.9B.5 System Model Quantatative Analysis 10.4.9B.5.1 Events Causes and Probabilities
To determine overall system unavailability, a probab ility of occurrence had to be established for each of the basic events on the fault tree. This was a ccomplished by identifying the applicable causes (from Subsection 10.4.9B.2.3) of each event, assigning probabilities to each cause, and summing the cause probabilities to obtain the event probability. Simple arithmetic summing of the cause probabilities was used because the "bracketing" correction terms woul d be insignificant because of the small numbers involved. The causes and probabilities of each event entering into the fault tree are given in Table 10.4.9B-6.
EC-33720, R307)
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CONTINUED HISTORICAL INFORMATION With the exception of testing and maintenance, selection of applic able causes for each event was straightforward. Applicability of test/maintenance causes to each event was determined on a case by case basis through a review of anticipated plant test and maintenance actions. This review is described in detail in Subsection 10.4.9B.5.1.1.
It should be noted that some of the causes of cert ain events are not expect ed to occur simultaneously, with some causes of other events appearing in the same cut sets. For example, if the "A" MDP was in maintenance during power operation, the Technical Specifications would not allow TDP maintenace without a plant shutdown. Performing the analysis to account for this would have unduly complicated the analysis without significantly improvi ng the predicted overall system reliab ility, so this was conservatively ignored.
10.4.9B.5.1.1 Unavailability Due to Testing and Maintenance
System testing/maintenance can contri bute to unavailability by two means:
-OUTAGE: Components/system are being tested/mainta ined in an inoperable state at the time operation is demanded.
-ERROR: Components realigned for the test/maint enance operation were not restored to their proper state following the operation by the test/maintenance crew.
A review of the Technical Specifications, ASM E Section XI, equipment vendor maintenance manuals, system operating procedures, etc. was conducted to identify testing/maintenance operations, their expected frequency and their potential for unavailability c ontribution from either outage or error. The sections herein on testing and maintenance summarize th is review. Table 10.4.9B-8 lists by component those maintenance/testing acts which were determined to contribute to unavailability.
SYSTEM TESTING
A review of system tests revealed that there is no unavailability cont ribution due to testing, primarily because:
a) All tests involve putting the component in its operat ional state, so that it is ready if system response is demanded during the test.
b) No realignment of manual valves is required for any system tests.
A discussion of system tests and their potential for unavailability contributions is given below:
PUMPS: The motor-driven and turbine-driven pumps must be tested in accordance with ASME Section XI Subsection IWP, which r equires a monthly test for speed, inlet pressure, p, flow rate, vibration and bearing temper ature. The Technical Specification 4.7.1.2.b requirement to measure pump di scharge pressure every 92 days is enveloped by the Section XI tests.
EC-33720, R307)
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CONTINUED HISTORICAL INFORMATION To perform these tests, the pump is started (by turning the control switch to start) and allowed to deliver flow back to the CSP through the minimum flow recirculation line. This is carried out in normal system alignmen t, and none of the measurements to be taken affect pump operation. If a system demand occurred during the test, the motor-driven pumps would continue running if offsite power were available, or would be tripped and restarted by the diesel generator load sequencer if offsite power were unavailable. The turbine driven pump would continue running in any case. As such, the quarterly tests are not deemed to contribute to unavailab ility either by outage or error done.
The Technical Specifications also require that the pumps be verified to start on an EFAS every 18 months (i.e., during a refueling s hutdown). This test will be performed by depressing the manual EFAS button(s) and obser ving that the appropriate pumps start.
No system valve realignment or temporary wi ring arrangements are required. The test is terminated by clearing the EFAS manual trip and turning the control switch to off. Since
the test is performed during plant shutdown and with no system realignment, there is no potential for unavailability from the te st either due to outage or error.
VALVES: The valves that are subject to testing under ASME Section XI, Subsection IWV, are listed in Table 10.4.9B-7.
Subsection IWV requires that these valves be exercised to the position required to fulfill their function every three months. For pow er operated valves, this includes timing the stroke to assure that valve closur e time is within acceptable limits.
For the power operated valves, the test involv es opening the valve by turning the control switch to "open" and measuring the time t he valve requires to open as observed by the valve position indicator. The valve is returned to its original position by turning the control switch to "close." If a system demand o ccurs while the valve is open or being opened, there is no effect on the system, since the va lve is already in or nearing its operational state. If a system demand occurs while t he valve is being closed, the valve would reverse itself and go to the operational state.
Thus, exercise testing of the power operated valves does not contribut e to system unavailability.
Each check valve subject to testing can be tested during the testing of the pumps and power operated valves. If a system demand were to occur either during or after testing, the check valve would be returned to its proper position by the fluid forces of system operation. Thus, testing of the check valves does not contribute to unavailability either by outage or errors.
CONTROL: The Section XI test for pumps and power operated valves is also CIRCUITS a control circuit test. This is a monthl y test for pumps and quarterly test for valves. As with the pump and valve tests, there is no contribution to system unavailability.
EC-33720, R307)
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CONTINUED HISTORICAL INFORMATION ACTUATING: Details of the testing of the EFAS logic are given in FSAR Section 7.3. As LOGIC demonstrated there, these tests do not affect generation of the EFAS on demand and thus do not contribute to EFS unavailability.
DIESEL: Details of the standby diesel generator testing are given in FSAR Section GENERATORS 8.3. As demonstrated t here, tests do not affect the ab ility of the diesel generators to respond on demand, and thus do not c ontribute to EFS unavailability.
SYSTEM MAINTENANCE
There is little or no incapacitating maintenanc e planned during plant operation on the components under consideration. In general, the only time such maintenance would be performed during operation would be if the component failed to function during a periodic te st. Unavailability due to th is is normally given by the mean time to repair divided by the mean time bet ween failure for the component. However, the plant Technical Specifications place an upper bound on how long the plant can be operated with the component in repair, so it is appropriate to use a mean time to repair based only on those repairs which take less time than the Technical Specifications LC O for that component. In addition, certain components cannot be repaired during plant operation, so ma intenance on these components has no potential for causing unavailability. Details of how maintenance contributes to unavailability for each component is discussed below. A summary listing of maintenance ac tions affecting each component is given in Table 10.4.9B-8.
PUMP: All planned maintenance for the pumps is to be performed during shutdown. MAINTENANCE The only time pump maintenance woul d be performed during operation would be if the pump failed to start during a routine Section XI test (discussed in the testing section).
This is expected to contribute an outage cont ribution for the pumps only on the order of 10-4 which is an insignificant addition to t he pump probability of failure to start on demand of 5 x 10
-3 (including the control circuit). Th is is believed to be a realistic estimate, but for consistency with Refe rence 1 (p. III-16) the following method was used:
Q MAINT = (0.22 maint. act/mo.) (7 hr./maint. act) __________________________________________ (720 hr/mo.)
= 2.1 x 10
-3 Major pump maintenance would require closing the pump discharge and suction
isolation valves to permit draining of the pump casing, introducing possible unavailability due to maintenance error. Howe ver, the position of these valves is rechecked at least every 31 days in accordanc e with the Technical Specifications. In addition, the position of these valves is moni tored by the plant computer. As such, the probability of the pump suction/discharge isol ation valves being left closed after pump maintenance is considered insignificant.
EC-33720, R307)
WSES-FSAR-UNIT-3 10.4.9B-13 Revision 307 (07/13)
(EC-33720, R307)
CONTINUED HISTORICAL INFORMATION In addition, any such work done on the TDP w ould require isolation of the steam supply by closing manual valve 18. However, since the pump is to be tested after
maintenance, the chance of the valve bei ng left closed unnoticed is not considered credible.
VALVE: Certain EFS valves are not accessi ble for maintenance during plant operation MAINTENANCE plant operation because t hey directly interface with pr essurized systems. Afault in such valves might require a plant shutdown in accordance with the LCO's which, while undesirable from an operations standpoint, virtually precludes the chance of maintenance on these valves from contributing to unavailability. These valves are: 64, 65, 66, 67, 68, 69, 70 and 71, (EFW isol ation valves) and 72, 73, 39, and 40 (TDP steam supply valves).
The only remaining EFS active valves on t he fault tree are the check valves at the pump discharges (valve 34, 35 and 36). There is no planned maintenance for these
valves during planned operation, so the only time valve maintenance would be
performed during operation would be if the va lve failed to function during a routine Section XI test (discussed in the testing section). However, for consistency with Reference 1 (p. III-16), the following method was used:
Q MAINT = (0.22 maint. act/mo.) (7 hr./maint. act)
_________________________________________
(720 hr/mo.)
= 2.1 x 10
-3 Repair on a pump discharge check valve w ould require closing the pump discharge and suction isolation valves to permit drainage of the piping section prior to disassembly if the valves. However, as with the pump repair, the probability of these valves being left closed after the check valve repair is negligible.
OTHER: There are two general plant maint enance activities which involve the EFS: MAINTENANCE the EFS: Water Treatment of the EFS and the Condensate and Feedwater Systems Pre-Startup Cleaning Operation. The potent ial for these activities affecting EFS availability is discussed below. (EC-34060, R306) a) EFS Water Treatment - This operati on injects chemicals (pH control agent and hydrazine) into the normally stagnant EFS as necessary to maintain water quality, and may be conducted during plant operation.
It is performed by opening Valves 6CF-V605 and V607 (on the EFS suction header), Valv es 64 and 70 (the inboard isolation valve on EFW flow path 1 to each SG) and Valves 20 and 21 (on the water treatment
recirculation lines). This operation has no potential for contributing to unavailability either by outage or error, as discussed bel ow. The two EFW isolation valves are placed in their operational state, so they would be ready if a system demand occurred during the operation. Similarly, even if they were erroneously left open by the maintenance crew, they would be in their operational state. (EC-34060, R306
- EC-33720, R307)
WSES-FSAR-UNIT-3 10.4.9B-14 Revision 307 (07/13)
(EC-33720, R307)
CONTINUED HISTORICAL INFORMATION (DRN 00-786, R11-A)
The chemical injection lines to the EFS suction header have check valves, which would prevent any backflow through these lines if a demand were to occur during the operation or following the operation and the maintenance cr ew erroneously left the isolation valves open. However, the line is only 1 in. in diameter compared to 6 in. for the header, so
there would be no significant loss of suction to the EFS pumps via these lines even if the isolation valves were left open and the check valves stuck open. (DRN 00-786, R11-A)
The water treatment recirculation lines are only 1 in. and have flow restrictors. Thus, even if the isolation valves in these lines were erroneously left open by the maintenance crew, no significant diversion of EFS flow would occur.
b) Condensate and Feedwater Systems Pre-Start up Cleaning Operation: In this operation, the condensate and feedwater systems are flushed to the main condenser and via a portion of the EFS. The Main Feedwater Isolation Valves are closed and the main feedwater flow path is diverted to the EFS by opening either Valve 62 or 63 (the valves are interlocked so that only one at a time may be opened).
The flow path to the main condenser is established by opening either Valve 60 or 61 (also interlocked). Since this operation is performed only during shutdown, there is no unavailability contribution due to outage, but there is a contribution from error as discussed below.
If Valve 62 or 63 was erroneously left open afte r the operation by the maintenance crew, the series check valve (37 or 38) would prev ent any diversion of EFS flow to the Main Feedwater System. However, as long as the MFWS remains intact and water solid, as it is assumed to be for the transients being analyz ed, there is no potential for flow diversion by these lines even if the check valves were frozen open and the motor operated valves were open. There is thus no unavailability contribution due to the valves on the lines connecting the EFS to the MFWS upstream of the MFIV's.
If Valve 60 or 61 was erroneously left open, as much as 700 gpm of EFS flow could be diverted from the SG's to the Main Condenser. However, one of the valves must be left open AND the turbine-driven pump must fail for this to cause system failure. Hand
calculations showed this to be an insignificant failure contributing mechanism, so it was not modeled into the fault tree.
Manual Valves 13, 15, 16, and 17, which ar e used to isolate the EFS header for this operation, could conceivably be left closed a fter the flushing operation leaving the EFS inoperable. A single valve or pair of valves could be left closed as well, but failure to leave all the valves closed is the most signific ant error since it is a system incapacitating common mode failure.
There are three major checkpoints at whic h this condition would be detected prior to plant startup. These, along with their probab ility to fail to be properly executed, are as follows:
EC-33720, R307)
WSES-FSAR-UNIT-3 10.4.9B-15 Revision 307 (07/13)
(EC-33720, R307)
CONTINUED HISTORICAL INFORMATION
- 1. System realignment: The operators/main tenance crew must fail to carry out the system realignment specified in the procedure for the prestartup condensate and feedwater cleanup operation. This is a fa ilure to use a valve restoration list, and is assigned a probability of 0.01 from Reference 2, p-15-9.
- 2. EFS flow path verification: The operators must fail to carry out the EFS flow path verification test (NUREG-0635 Recomm endation GS-6; see Appendix 10.4.9A) which, if performed, would readily detect the valve mispositioning. This is a failure to carry a plant policy, and is assigned a probability of 0.01 from
Reference 2, p. 15-9.
- 3. EFS status monitoring: The control r oom operators must fail to notice the EFS annunciator on the ESF bypassed and inoperable status indication insert, which would be lighted in response to the position indicators on the valves. This is a failure to detect a deviant status ligh t, and is assigned a probability of 0.01 from Reference 2, p. 11-17.
Assuming that the three check points are independent, the probability of all three failing to be carried out is 1 x 10
-6 . However, recognizing that t he checkpoints are not totally independent (they are all carried out by the same plant operating staff), the probability of ME1 is raised judgementally to 5 x 10
-6.
10.4.9B.5.2 System Failure Probability Analysis
The overall system failure probability was determined from the minimal cut sets and individual event probabilities using an option of the KITT 1 Code. In essence, the probability of each cut set is determined by multiplying the probability of each event in the cut set, and the system failure probability is determined by adding the probability of each cut set. No correct ions for simultaneous occurrence (i.e., bracketing) were made, as the numbers involved are quite small. The results are as follows:
_____________________________________________________
___
_____________________________________________________
CASE 1 1.42 x 10
-5 CASE 2 3.97 x 10
-5 CASE 3 2.63 x 10
-2 _____________________________________________________
EC-33720, R307)
WSES-FSAR-UNIT-3 10.4.9B-16 Revision 307 (07/13)
(EC-33720, R307)
CONTINUED HISTORICAL INFORMATION 10.4.9B.6 Discussion of Results
CASE 1 The dominant cut sets for Case 1 and their relative contributions to system failure are given on Table 10.4.9B-9. The dominant cut sets fall in to four basic system failure modes:
a) Maintenance errors, specifically MEI, which is discussed in detail in Subsection 10.4.9B.5.1.1 (cut set 1). This contributes 35.2 percent of total system failure probability.
b) Failure of one of the pumps to start coupled with its discharge check valve sticking open, which diverts the other pumps flow from the SGs to reci rculate through the idle pump loop (cut sets 4, 9, 10, 11, 12 & 15). These failure types contribute 26.4 percent of total system failure probability.
c) Failure of both automatic and operator backup actuat ion of the system (cut sets 17, 18, 19 & 20).
These failure types contribute 14.0 percent of total system failure probability.
d) Failure of both motor driven pumps coupled with failures in the turbine driven pump steam supply system (cut sets 76, 80 & 84). These failure types contribute 7.3 percent of total system failure probability.
The above failure modes account for 82.9 percent of to tal system failure probability. The remaining 17.1 percent is from over 193 cut sets of lesser importance.
The absolute value of the Waterford 3 EF S unavailability for Case 1 of 1.42 x 10
-5 is in the high reliability range of Reference 1 (unavailability between 10
-4 and 10-5.
CASE 2 The dominant cut sets for Case 2 and their relative c ontributions to system failure are given in Table 10.4.9B-10. The dominant cut sets fall into the same four basic system failure modes as Case 1:
a) Maintenance errors (cut set 1) - 12.6 per cent of total system failure probability.
b) Failure of one pump to start coupled with its di scharge check valve sticking open (cut sets 4, 5, 10, 11, 12, 16 & 17) - 27.2 percent of total system failure probability.
c) Failure of both automatic and operator backup actuat ion of the system (cut sets 19, 20, 21 & 22) -
4.8 percent of total system failure probability.
d) Failure of both motor driven pumps coupled with failures in the turbine driven pump or its steam supply system (cut sets 92, 97, 102, 107, 137, 142, 147 & 152) - 30.6 percent of total system failure probability.
EC-33720, R307)
WSES-FSAR-UNIT-3 10.4.9B-17 Revision 307 (07/13)
(EC-33720, R307)
CONTINUED HISTORICAL INFORMATION The above failure modes account for 75.2 percent of to tal system failure probability. The remaining 24.8 percent is from over 274 cut sets of lesser import ance. The difference between Case I and Case 2 was due to the fact that a motor driven pump failure can be c aused either by a direct pump failure or by failure of its associated diesel generator.
The absolute value of the Waterford 3 EF S unavailability for Case 2 of 3.97 x 10
-5 is in the high reliability range of Reference 1 (unavailability between 10
-4 and 10-5.
CASE 3 The dominant cut sets for Case 3 and their relative contributions to system failure are given on Table 10.4.9B-11. As expected, there ar e a number of one event cut sets, since the motor-driven pumps are deemed inoperable by the initial condition of Station Black out for this case. The dominant contributions to system failure potential for this case are the turb ine-driven pump and its governor valve, speed controller and overspeed protection, which comprise roughly 90 percent of the total causes.
The absolute value of EFS reliability for Case 3 is in the medium range of Reference 1 (unavailability between 10
-1 and 10-2.
10.4.9B.7 Conclusions
No acceptance criteria for this study were given, but as noted in the previous section the results were good when compared to the other plants studied in Refer ence 1. The main reasons that favorable results were achieved are:
a) The active components and flow paths are redundan t, so there are no single point vulnerabilities.
b) The system is automatically act uated, so no human action is required.
c) System design is such that all routine test ing can be done with no incapacitating realignments or locking out of components.
d) All anticipated maintenance is performed during plant shutdown.
e) There are few interconnections with other systems, minimizing t he potential for adverse interactions with other systems.
f) Position of most of the manual valves in t he system are monitored by the plant computer, minimizing the potential that t hese valves are mispositioned.
Other than ME1, the analysis did not uncover any areas where minor changes could result in major reliability improvements. Reliability has always been a subjective consideration in the design and intended operating/maintenance practices for this system, and this quantitative reliability analysis confirmed that.
EC-33720, R307)
WSES-FSAR-UNIT-3 10.4.9B-18 Revision 307 (07/13)
(EC-33720, R307)
CONTINUED HISTORICAL INFORMATION Regarding ME1, the potential for error could be elimi nated by not closing Valves 13, 14, 16 & 17 during the prestartup condensate and feedwater cleanup operat ion, i.e., rely on the pump discharge check valves to prevent backflow to the CSP during t he operation. This will be investigated and will be incorporated into the procedure if f easible. This would improve system reliability beyond the values given in this report if incorporated.
This study was useful in demonstrati ng that the Waterford 3 EFS is of high reliability, and that there were no major faults in the system design. However, care should be taken in applying the numerical results too literally. In particular, the unavailability repor ted for Case 1 begins to approach a judgemental lower bound on achievable unavailability for any system due to unidentified common cause failures. For this reason, there is probably little actual system reli ability improvements to be gained even by major changes such as adding more pumps.
References:
- 1. Letter from D. Ross to all Westinghouse and Combustion Engineering Operating License Applicants, dated March 10, 1980.
- 2. NUREG/CR-1278, "Handbook of Human Reliability Analysis with Emphasis on Nuclear Power Plant Applications," October 1980.
END OF HISTORICAL INFORMATION (EC-33720, R307)
WSES-FSAR-UNIT-3 TABLE 10.4.9B-1 (Sheet 1 of 5) Revision 307 (07/13) (EC-33720, R307)
START OF HISTORICAL INFORMATION COMPONENT LIST MANUAL VALVES
VALVE NUMBER DESCRIPTION FMEA SEGMENT
- 1:EFW-102B/3CD-V111B Isolation valve on CSP suction line "B" I
- 2:EFW-102A/3CD-VIIOA Isolation valve on CSP suction line "A" I
3:3CC-V211B Isolation valve on line to alternate water I source for suction line "B" 4:3CC-V201A Isolation valve on line to alternate water I source for suction line "A"
- 5:EFW-103A/3CD-V145A/B Isolation valve on suction header between I "A" MDP and TDP
- 6:EFW-103B/3CD-V146A/B Isolation valve on suction header between I TDP and "B" MDP
- 7:EFW-106A/3CD-V112A Isolation valve on "A" MDP suction I
- 8:EFW-106A/B/3CD-V114A/B Isolation valve on TDP suction I
- 9:EFW-106B/3CD-V113B Isolation valve on "B" MDP suction I 10:EFW-201A/3FW-V15O5-16 Isolation valve on "A" MDP mini-flow recirc line I.A 11:EFW-201A/B/3FW-V1503-7 Isolation valve on TDP mini-flow recirc line II.T.2 12:EFW-201B/3FW-1505-17 Isolation valve on "B" MDP mini-flow recirc line II.B
- 13:EFW-211A/3FW-604A Isolation valve on "A" MDP discharge II.A
- 14:EFW-211A/B/3FV-606A/B Isolation valve on TDP discharge II.T.2
- 15:EFW-211B/3FW-V605B Isolation'valve on "B" MDP discharge II.B
- 16:EFW-215A/3FW-V608 Isolation valve on discharge header between III.I "A" MDP and TDP
- 17:EFW-215B/3FW-V609 Isolation valve on discharge header between III TDP and "B" MDP 18:MS-415/3MS-678A/B Isolation valve on TDP steam supply line III.T.1
- 19:FW-205/3FW-V619A/B Isolation valve on mini-flow recirculation - line CSP *Valve is position monitored by the plant computer EC-33720, R307)
WSES-FSAR-UNIT-3 TABLE 10.4.9B-1 (Sheet 2 of 5) Revision 307 (07/13) (EC-33720, R307)
CONTINUED HISTORICAL INFORMATION COMPONENT LIST MANUAL VALVES
VALVE NUMBER DESCRIPTION FMEA SEGMENT
20:EFW-22SA/2FW-VI501-1 Isolation valve on water treatment recirculation III.1 line serving SGI branch
21:EFW-227B/2FW-VI501-2 Isolation valve on water treatment recirculation III.2 line serving SG2 branch
22:3MS-V753 Isolation valve on TDP steam supply line drip pot II.T.1 flush line
23:MS-409/5MS-V649-7 Isolation valve on TDP steam supply line drip pot II.T.1 normal drain line
24:MS-408/SMS-V649-8 Isolation valve on TDP steam supply line drip pot II.T.1 comon drain line
25:CF-114/6CF-V605 Isolation valve on line from hydrazine pump I (for chemical treatment)
26:CF-212/6CF-V607 Isolation valve on line from ammonia line I (for chemical treatment)
VALVE NUMBER DESCRIPTION FEMA SEGMENT
31:EFW-204A/3FW-VI507-2 "A" MDP mini-flow recirculation line II.A
32:EFW-204A/B3FW-VI517 TDP mini-flow recirculation line II.T.2
33:EFW-204B/3FW-VI507-1 "B" MDP mini-flow recirculation line II.B
34:EFW-207A/3FW-V601A "A" MDP discharge line II.A
35:EFW-207A/B/3FW-V603A/B TDP discharge line II.T.2
36:EFW-207B/3FW-V602B "B" MDP discharge line II.B
37:FW-18OA/3FW-V837A Prestartup cleanup line from MFW serving SGI III.1 branch
38:FW-18OB/3FW-V838B Pre-startup cleaning line from MFW serving SG2 III.2 branch EC-33720, R307)
WSES-FSAR-UNIT-3 TABLE 10.4.9B-1 (Sheet 3 of 5) Revision 307 (07/13) (EC-33720, R307)
CONTINUED HISTORICAL INFORMATION COMPONENT LIST CHECK VALVES VALVE NUMBER DESCRIPTION FEMA SEGMENT 39:MS-402A/3MS-V676A TDP steam supply line from SG1 II.T.1 40:MS-402B/3MS--V677B TDP steam supply line from SG2 II.T.1 41:5MS-V722 TDP steam supply line drip pot common drain II.T.1 line 42:EFW-2191A/3FW-V1541A TDP & MDP discharge header line to SGI III.1
43:EFW-2191B/3FW-V1541B TDP & MDP discharge header line to SG2 III.2 POWER OPERATED VALVES (inc luding control circuits) (EC-3926, R304)
+60:EFW-22OA/3FW-V607A Pre-startup cleanup line to SG blowdown serving III.1 SGI branch
+61:EFW-22OB/3FW-V61OB Pre-Startup cleanup line to SG blowdown serving III.2 SG2 branch
+62:FW-179A/3FW-V839A Pre-startup cleanup line from MFW serving SG1 III.1 branch +63:FV-179B/3FW-V84OB Pre-startup cleanup line from MEV serving SG2 III.2 branch (EC-3926, R304) 64:EFW-224A/2FW-V85IB(Air) Inboard isolation on SG1 EFW Path 1 III.1
- 65:EFW-22BA/2FW-V848A(Air) Outboard isolation on SG1 EFV Path 1 III.1 66:EFW-223A/2FW-V852A(Air) Inboard isolation on SG1 EFV Path 2 III.1
- 67:EFW-229A/2FW-V847B(Air) Outboard isolation on SG1 EFV Path 2 III.1 68:EFW-223B/2FW-VB54B(Air) Inboard isolation on SG2 EFV Path 2 III.2
- 71:EFW-228B/2FW-V85OB(Air) Outboard isolation on SG2 EFW Path 1 III.2
- 72:2MS-V611A(Motor) TDP steam supply line from SG1 II.T.1
- Valve has position indi cation in control room.
+Motor Operator Abandoned in Place EC-33720, R307)
WSES-FSAR-UNIT-3 TABLE 10.4.9B-1 (Sheet 4 of 5) Revision 307 (07/13) (EC-33720, R307)
CONTINUED HISTORICAL INFORMATION COMPONENT LIST PUMPS PUMP CAPACITY FEMA SEGMENT
- 73:2MS-V612B(Motor) TDP steam supply line form SG2 II.T.1
- 74:MS-416(Motor) TDP trip and throttle valve II.T.1
75:MS-417(Hydr) TDP governor valve II.T.1
- 76:MS-412/3MS-V684(Motor) TDP steam supply line drip pot normal drain II.T.1 Line
78:MS-410/MS-V716(Air) TDP steam supply line drip pot drain to EDS II.T.1
85:"A" MOTOR DRIVEN* 450 gpm + 45 gpm recirc. @ SG Pres = 1050 psi II.A
86:TURBINE DRIVEN 700 gpm + 80 gpm recirc. II.T.2
87:"B" MOTOR DRIVEN* 450 gpm + 45 gpm recirc. @ SG Pres = 1050 psi II.B EC-33720, R307)
WSES-FSAR-UNIT-3 TABLE 10.4.9B-1 (Sheet 5 of 5) Revision 307 (07/13) (EC-33720, R307)
CONTINUED HISTORICAL INFORMATION COMPONENT LIST ACTUATING LOGIC
SIGNAL PURPOSE FEMA SEGMENT(S)
90:EFAS 1"A" Indicates that SGI is intact and is in need II.A; II.T.1; of EFW; ACTUATES "A" MDP and Valves 65, 66 & 72 III.1 (TDP)
91:EFAS 2"A" Indicates that SG2 is intact and is in need of II.A; II.T.1; EF'W; ACTUATES "A" MDP and Valves 69, 70, & 73 III.2 (TDP)
92:EFAS 1"B" Indicates that SGI is intact and is in need of II.B; II.T.1; EFW; actuates "B" MDP and Valves 64, 67 & 72 III.1 (TDP)
93:EFAS 2"B" Indicates that SG2 is intact and is in need of III.B; II.T.1; EFW; acutates "B" MDP and Valves 68, 71 & 73 III.2 (TDP)
94:TDP Overspeed Indicates failure of TDP speed control; closes II.T.1 TDP steam stop valve (Valve 74)
95:TDP Speed Control Regulates TDP governor valve (Valve 75) as II.T.1 necessary to maintain pump speed
POWER SUPPLIES
SYSTEM SERVICES COMPONENTS FMEA SEGMENT
80:SA ac-4kV & 480V "A" MDP II.A
81:SB ac-4kV & 480V "B" MDP II.B
_____________________
- Includes control circuit
END OF HISTORICAL INFORMATION (EC-33720, R307)
WSES-FSAR-UNIT-3 TABLE 10.4.9B-2 (Sheet 1 of 9) Revision 307 (07/13) (EC-33720, R307)
START OF HISTORICAL INFORMATION EFS FAILURE MODES AND EFFECTS ANALYSIS
COMPONENT COMPONENT STATE EFFECT INHERENT COMPENSATION
I. CONDENSATE SUPPLY (SUCT ION TO EFS PUMPS)
- Manual Valve 1 - Open Normal State ---
EFW-102B/CD-V111B
- Closed Loss of CSP Suction Line CSP Suction Lines "A" "B" to all EFW pumps available to all EFW pumps
- Manual Valve 2 - Open Normal State ---
EFW-102A/3CD-V110A
- Closed Loss of CSP Suction Line CSP Suction Line "B" "A" to all EFW pumps available to all EFW pumps
- Manual Valve 3 - Open Potential for CSP draining None, but there is a manual butterfly 3CC-V211B to Wet Cooling Tower Basin valve (3CC-B306B) which is locked closed upstream of 3CC-V211B
- Closed --- ---
- Manual Valve 4 - Open Potential for CSP draining None, but there is a manual butterfly 3CC-V210A to WCT Basin valve (3CC-B305B) which is locked closed upstream of 3CC-V212A
- Manual Valve 5 - Open Normal State ---
3CD-V145A/B; EFW-103A
- Closed Loss of CSP Suction Line "A" CSP Suction Line "B" available to TDP and "B" MDP and loss to TDP and "B" MDP and VSP of CSP Suction Line "B" to Suction Line "A" available to "A" MDP "A" MDP
- Manual Valve 6 - Open Normal State ---
3CD-V146A/B; EFW-103B
- Closed Loss of CSP Suction Line "B" CSP Suction Line "A" to TDP and "A" MDP and loss available to TDP and "A" of CSP Suction Line "A" to MDP and CSP Suction Line "B" MDP "B" available to "B" MDP
- Manual Valve 7 - Open Normal State ---
3CD-V112A; EFW-106A
- Closed Loss of all suction sources None, but TDP and "B" MDP to "A" MDP not affected.
- Manual Valve 8 - Open Normal State ---
3CD-V114A/B; EFW-106A/B
- Closed Loss of all suction sources None, but "A" MDP and "B" to TDP MDP not affected (EC-33720, R307)
WSES-FSAR-UNIT-3 TABLE 10.4.9B-2 (Sheet 2 of 9) Revision 307 (07/13) (EC-33720, R307)
CONTINUED HISTORICAL INFORMATION COMPONENT COMPONENT STATE EFFECT INHERENT COMPENSATION
- Manual Valve 9 3CD-V113B; - Open Normal State None, but TDP and "A" EFW-106B - Closed Loss of all suction sources MDP not affected to "B" MDP
- Manual Valve 19 3FW-619A/B; - Open Normal State None, but system initial start FW-205 - Closed Loss of mini-flow recirculation; no not affected immediate effect, but possible pump damage when SG isolation valves cycle closed
Manual Valve 25 CF-114/6CF-V605 - Open Insignificant - see Subsection 10.4.9B.5.1.1.a --- Closed Normal State ---
Manual Valve 26 CF-212/6CF-V607 Open Insignificant - see Subsection 10.4.9B.5.1.1.a --- - Closed Normal State ---
II.A "A" MOTOR DRIVEN PUMP BLOCK
- Pump/Motor - Fails to start Fluid not delivered towards header None, but TDP and "B" MDP not affected
- SA ac Power (4kV & 480V) - Fails to energize pump motor Fluid not delivered towards header None, but TDP and "B" MDP not affected
- EFAS 1 "A" Logic - Signal not generated Loss of one of tw o automatic start signals EFAS 2 "A" starts pump; to pump Operator could start pump
- EFAS 2 "A" Logic - Signal not generated Loss of one of tw o automatic start signals EFAS 1 "A" starts pump; to pump Operator could start pump
- Manual Valve 10 - Open Normal State EFW-201A/3FW-V1505 Closed Loss of "A" MDP mini-flow recirculation no immediate effect, but possible None, but TDP and "B" MDP not pump damage when SG isolation affected; "A" MDP initial valves cycle closed response not affected
- Check Valve 31 - Open (against forward current) Proper State ---
EFW-204A/3FW-V1507-2
- Closed (against reverse current)
- Open (against reverse current) TDP and "B" MDP partial mini-flow recirculation --- through idle "A" MDP loop; No problem
- Closed (against forward current) Loss of "A" MDP mini-flow recirculation; N one, but TDP and "B" MDP not no immediate effect, but possible affected; "A" MDP initial start pump damage when SG isolation not affected valves cycle closed (EC-33720, R307)
WSES-FSAR-UNIT-3 TABLE 10.4.9B-2 (Sheet 3 of 9) Revision 307 (07/13) (EC-33720, R307)
CONTINUED HISTORICAL INFORMATION COMPONENT COMPONENT STATE EFFECT INHERENT COMPENSATION
- Check Valve 34 - Open (against Proper State ---
EFW-207A/3FW-V601A forward current)
- Closed (against Proper State ---
reverse current)
- Open (against Most TDP and "B" MDP flow None, unless Valve 7 or 13 reverse current) diverted from SGs to recir mispositioned closed through idle "A" MDP loop; (fortuitous failure) negation of system function
- Closed (against Fluid not delivered towards None, but TDP and "B" MDP not forward current) header affected
- Manual Valve 13 - Open Normal State ---
EFW-211A/3FW-V604A
- Closed Fluid not delivered towards None, but TDP and "B" MDP not header affected
II.T.1 TURBINE DRIVEN PUMP STEAM SUPPLY
- Motor Op. Valve 72 - Open Proper Operation ---
- Closed Loss of SG1 steam supply to SG2 steam supply not affected TDP
- Check Valve 39 - Open (against Proper Operation ---
MS-402A/3MS-V676A forward current)
- Closed (against Loss of SG1 steam supply to SG2 steam supply not affected forward current) TDP
(Reverse current will not occur under the conditions analyzed)
- Motor Op. Valve 73 - Open Proper Operation ---
- Closed Loss of SG2 steam supply to SG1 steam supply not affected TDP
- Check Valve 40 - Open (against forward Proper State MS402B/3MS-V677B current)
- Closed (against forward Loss of SG2 steam supply - SG1 steam supply available current) to TDP (Reverse current will not occur under the conditions analyzed).
- Manual Valve 18 - Open Normal State None, but "A" and "B" MS415/3MS-V678A/B - Closed Loss of all steam supply MDPs not affected to TDP (EC-33720, R307)
WSES-FSAR-UNIT-3 TABLE 10.4.9B-2 (Sheet 4 of 9) Revision 307 (07/13) (EC-33720, R307)
CONTINUED HISTORICAL INFORMATION COMPONENT COMPONENT STATE EFFECT INHERENT COMPENSATION
- Motor Op. Valve 74 - Open Normal State ---
MS416 - Closed Loss of all steam supply None, but "A" and "B" MDPs to TDP not affected
- Hyd. Op. Valve 75 - Open Normal State ---
MS417 - Closed Loss of all steam supply None, but "A" and "B" MDPs to TDP not affected
- EFAS1 "A" Logic Failure to be generated Loss of one group of EFAS1 "B" Opens Valve 72 automatic open signals to Valve 72
- EFAS1 "B" Logic Failure to be generated Loss of one group of EFAS1 "A" Opens Valve 72 automatic open signals to Valve 72
- EFAS2 "A" Logic Failure to be generated Loss of one group of EFAS2 "B" Opens Valve 73 automatic open signals to Valve 73
- EFAS2 "B" Logic Failure to be generated Loss of one group of EFAS2 "A" Opens Valve 73 automatic opens signals to Valve 73
- Valves 22,23,24 These valves are on drain lines serving the TDP steam supply line drip pot, and as such, 41,76,77 & 78 must be evaluated for their potential to divert steam fr om the TDP. Be cause of their small size (1 in. - 2 in.) they are not considered to be capable of diverting any significant quantity of steam.
II.T.2 TURBINE DRIVEN PUMP BLOCK
- Pump/Turbine Fails to start Fluid not delivered towards None, but "A" and "B" MDPs header not affected
- Manual Valve 11 - Open Normal State ---
EFW-201A/B/3FW-V1503-7
- Closed Loss of TDP mini-flow recir- None, but "A" and "B" MDPs culation; no immediate effect, not affected; TDP initial but possible pump damage start not affected when SG isolation valves cycle closed
Check Valve 32 - Open (against Proper State ---
EFW-204A/B3FW-V5I7 forward current)
- Closed (against reverse current) (EC-33720, R307)
WSES-FSAR-UNIT-3 TABLE 10.4.9B-2 (Sheet 5 of 9) Revision 307 (07/13) (EC-33720, R307)
CONTINUED HISTORICAL INFORMATION COMPONENT COMPONENT STATE EFFECT INHERENT COMPENSATION
- Check Valve 32 - Open (against "A" and "B" MDP partial mini- --- EFW-204A/B3FW-V517 reverse current) flow recirculation through (cont'd) idle TDP loop; No problem
- Closed (against Loss of TDP mini-flow recir- None, but "A" and "B" MDPs forward current) culation; no immediate effect, not affected; TDP initial but possible pump damage when start not affected SG isolation valves cycle closed
- Check Valve 35 - Open (against Proper Operation ---
EFW-207A/B3FW-V603 A/B forward current)
- Closed (against Proper Operation reverse current)
- Closed (against Fluid not delivered towards None, but "A" and "B" MDPs forward current) header not affected
- Open (against Most "A" and "B" MDP flow None, unless Valve 8 or 14 reverse current) diverted from SG's to recir- mispositioned closed culation through idle TDP loop; (fortuitous failure) negation of system function
- Manual Valve 14 - Open Normal State ---
EFW-211A/B/3FW-V606 A/B
- Closed Pump doesn't deliver fluid None, but "A" and "B" MDPs towards header not affected
II.B "B" MOTOR DRIVEN PUMP BLOCK
- Pump/Motor Fails to start Fluid not delivered towards None, but "A" MDP and TDP not header affected
- SB ac Power Fails to energize Fluid not delivered towards None, but "A" MDP and TDP not (4kV & 480V) pump motor header affected
- EFAS 1 "B" Logic Signal not generated Loss of one of two auto start EFAS 2 "B" or Operator starts signals to pump pump
- EFAS 2 "B" Logic Signal not generated Loss of one of two auto start EFAS 2 "B" or Operator starts signals to pump Pump
- Manual Valve 12 - Open Normal State ---
EFW-201B/3FW-V1505-17
- Closed Loss of "B" MDP mini-flow None, but "A" MDP and TDP not recirculation; no immediate affected; "B" MDP initial effect, but possible pump response not affected damage when SG isolation valves cycle closed (EC-33720, R307)
WSES-FSAR-UNIT-3 TABLE 10.4.9B-2 (Sheet 6 of 9) Revision 307 (07/13) (EC-33720, R307)
CONTINUED HISTORICAL INFORMATION COMPONENT COMPONENT STATE EFFECT INHERENT COMPENSATION
Check Valve 33 - Open (against Proper State ---
EFW-204B/3FW-V1507-1 forward current)
- Closed (against Proper State ---
reverse current)
- Open (against "A" MDP and TDP partial mini- ---
reverse current) flow recirculation through idle "B" MDP loop; no problem
- Closed (against Loss of "B" MDP mini-flow None, but "A" MDP and TDP, forward current) recirculation; no immediate MDP not affected; "B" MDP effect, but possible pump initial start not affected damage when SG isolation valves cycle closed
- Check Valve 36 - Open (against Proper State ---
EFW-207B/3FW-V602B forward current)
- Closed (against Proper State ---
reverse current)
- Open (against Most "A" MDP and TDP flow diverted None, unless Valve 9 or 15 reverse current) from SGs to recirc through idle mispositioned closed "B" MDP loop; negation of (fortuitous failure) system function
- Closed (against Fluid not delivered towards header None, but "A" MDP and TDP forward current) not affected
- Manual Valve 15 - Open Normal State ---
EFW-211B/3FW-V605B - Closed Fluid not delivered towards header None, but "A" MDP and TDP not affected III.1 SG1 FLOW PATH
- Manual Valve 16 - Open Normal State ---
EFW-215A/3FW-V608
- Closed "A" MDP can't feed SG2; TDP & TDP & "B" MDP can feed SG2; "B" MDP can't feed SG1 "A" MDP can feed SG1 (EC-3926, R304)
- Manual Valve 60 - Closed Normal State --- FW-220A/3FW-V607A
- Open Diversion of up to 700 gpm EFW flow At least 700 gpm EFW flow from SGs to Main Condenser available to SGs (EC-3926, R304
- EC-33720, R307)
WSES-FSAR-UNIT-3 TABLE 10.4.9B-2 (Sheet 7 of 9) Revision 307 (07/13) (EC-33720, R307)
CONTINUED HISTORICAL INFORMATION COMPONENT COMPONENT STATE EFFECT INHERENT COMPENSATION
- Check Valve 37 - Closed (against Proper State ---
FW-180A/3FW-V837A reverse current)
- Open (against Possible diversion EFS flow Series Valve 62 closed.
reverse current) from SGs to MFW Also, MFW System intact and solid for transients under consideration (Forward current not deleterious to operation)
Check Valve 42 - Open (against Proper State ---
3FW-V1541A forward current)
- Closed (against Proper State ---
reverse current)
- Open (against Fluid not delivered SG2 flow path not affected reverse current) towards SG1
- Closed (against Fluid not delivered SG2 flow path not affected forward current) towards SG1 (EC-3926, R304)
- Manual Valve 62 - Closed Normal State --- FW-179A/3FW-839A
- Open Possible diversion of EFS flow Series Check Valve 37 closed.
from SGs to MFW if check valves Also, MFW System Intake and 37 open against reverse solid for transients under current consideration (EC-3926, R304)
- Air Op. Valve 64 - Open Proper Operation ---
EFW-224A/2FW-851B
- Closed Loss of SG1 EFW path 1 SG1 EFW path 2 not affected
- Manual Valve 20 - Closed Normal State ---
EFW-225A/2FW-V1501-1
- Open None; 1 in. line with flow ---
restrictor will not divert any significant EFW flow
- Air Op. Valve 65 - Open Proper Operation ---
EFW-228A/2FW-V848A
- Closed Loss of SG1 EFW Path 1 SG1 EFW path 2 unaffected
- Air Op. Valve 66 - Open Proper Operation ---
EFW-223A/2FW-V852A
- Closed Loss of SG1 EFW path 2 SG1 EFW path 1 unaffected (EC-33720, R307)
WSES-FSAR-UNIT-3 TABLE 10.4.9B-2 (Sheet 8 of 9) Revision 307 (07/13) (EC-33720, R307)
CONTINUED HISTORICAL INFORMATION COMPONENT COMPONENT STATE EFFECT INHERENT COMPENSATION
- Air Op. Valve 67 - Open Proper Operation ---
EFW-229A/2FW-B847B
- Closed Loss of SG1 EFW path 2 SG1 EFW path 1 unaffected
- EFAS 1 "A" Logic - Signal not generated Valves 65 & 66 do not open; SG2 EFW paths unaffected; Both SG1 paths lost Operator can open valves
- EFAS 1 "B" Logic - Signal not generated Valves 64 & 67 do not open; SG2 EFW paths unaffected; Both SG1 paths lost Operator can open valves
III.2 SG2 FLOW PATH
- Manual Valve 17 - Open Normal State ---
EFW-215B/3FW-V609
- Closed "A" MDP and TDP can't feed SG2; "B" MDP can feed SG2; "A" "B" MDP can't feed SG1 MDP & TDP can feed SG1 (EC-3926, R304)
- Manual Valve 61 - Closed Normal State --- EFW-220B/3FW-V601B
- Open Diversion of up to 350 gpm At least 1050 gpm EFW EFW flow from SGs to Main flow available to SGs Condenser (EC-3926, R304)
- Check Valve 38 - Closed (against Proper State ---
FW-180B/3FW-V838B reverse current)
- Open (against Possible diversion EFS flow Series Valve 63 closed.
reverse current) from SGs to MFW Also, MFW intact and solid for transients under consideration
(Forward current not deleterious to operation)
- Check Valve 43 - Open (against Proper State ---
3FW-V1542B forward current)
- Closed (against Proper State ---
reverse current)
- Open (against Fluid not delivered SG1 flow path not affected reverse current) towards SG2
- Closed (against Fluid not delivered towards SG2 SG1 flow path not affected forward current)
(EC-33720, R307)
WSES-FSAR-UNIT-3 TABLE 10.4.9B-2 (Sheet 9 of 9) Revision 307 (07/13) (EC-33720, R307)
CONTINUED HISTORICAL INFORMATION COMPONENT COMPONENT STATE EFFECT INHERENT COMPENSATION (EC-3926, R304)
- Manual Valve 63 - Closed Normal State --- FW-179B/3FW-V840B
- Open Possible diversion of Series Check Valve 38 closed.
EFS flow from SGs to Also, MFW System intact and MFW if check valve 38 solid for transients under open against reverse consideration current (EC-3926, R304)
- Air Op. Valve 68 - Open Proper Operation ---
EFW-223B/2FW-V854B
- Closed Loss of SG2 EFW path 2 SG2 EFW path 1 unaffected
- Air Op. Valve 69 - Open Proper Operation ---
EFW-229B/2FW-V849A
- Closed Loss of SG2 EFW path 2 SG2 EFW path 1 unaffected
- Air Op. Valve 70 - Open Proper Operation ---
EFW-224B/2FW-V853A
- Closed Loss of SG2 EFW path 1 SG2 EFW path 2 unaffected
- Manual Valve 21 - Closed Normal State ---
EFW-227B/2FW-V1530-2
- Open None; 1 in. line with flow ---
restrictor will not divert any significant EFW flow
- Air Op. Valve 71 - Open Proper Operation ---
EFW-228B/2FW-V850B Closed Loss of SG2 EFW path 1 SG2 EFW path 2 unaffected
- EFAS 2 "A" Logic - Signal not generated Valves 69 & 70 do not open; SG1 EFW paths unaffected; Both SG2 EFW paths lost Operator can open valve
- EFAS 2 "B" Logic - Signal not generated Valves 68 & 71 do not open; SG1 EFW paths unaffected; Both SG2 EFW paths lost Operator can open valves
IV. OVERALL SYSTEM FUNCTION
(DRN 00-786, R11-A)
As noted in Subsection 10.4.9B.2.1 system minimum function is fulfilled when a total of 450 gpm is delivered to the steam gener ator(s). This can be accomplished if any one of the pumps is able to deliver fluid to any one steam generator(s). Thus, using DeMorgans theorem, system functi on is not fulfilled if all of the pumps are unable to deliver fluid to both steam generators, i.e. "A" MDP can't deliver to SG1 and "A" MDP can't deliver to SG2 and "B" MDP can't deliver to SG1 and "B" MDP can't deliver to SG1 and "B" MDP can't deliver to SG2 and TDP can't deliver to SG1 and TDP can't deliver to SG2. (DRN 00-786, R11-A)
These failure conditions effectively relate failures of the system blocks to overall system function.
END OF HISTORICAL INFORMATION (EC-33720, R307)
WSES-FSAR-UNIT-3 TABLE 10.4.9B-3 (Sheet 1 of 4) Revision 307 (07/13)
(EC-33720, R307)
START OF HISTORICAL INFORMATION MINIMAL CUT SETS - CASE 1
ME1 7 8 9 1 2 87 6 2 42 43 87 7 8 36B 9 36A 6 2 36B 87 36A 7 8 36B 36A 15 6 2 36B 15 15 7 8 35B 8 18 7 9 35B 18 18 87 7 35B 74 18 36A 7 35B 75 18 15 7 35B 94 74 7 9 35B 95 74 87 7 35B 86 74 36A 7 35B 35A 74 15 7 35B 14 75 7 9 34B 7 75 87 7 34B 85 75 36A 7 34B 34A 75 15 7 34B 13 94 7 9 92 OEI 93 94 87 7 92 91 OE1 94 36A 7 92 OE1 93 94 15 7 90 OE1 93 95 7 9 90 91 OE1 95 87 7 9 6 2 95 36A 7 7 1 5 (EC-33720, R307)
WSES-FSAR-UNIT-3 TABLE 10.4.9B-3 (Sheet 2 of 4) Revision 307 (07/13)
(EC-33720, R307)
CONTINUED HISTORICAL INFORMATION MINIMAL CUT SETS-CASE 1
95 15 7 85 75 87 86 7 9 85 75 36A 86 87 7 85 75 15 86 36A 7 85 94 9 86 15 7 85 94 87 35A 7 9 85 94 36A 35A 87 7 85 94 15 35A 36A 7 85 95 9 35A 15 7 85 95 87 14 7 9 85 95 36A 14 87 7 85 95 15 14 36A 7 85 86 9 14 15 7 85 86 87 85 1 5 85 86 36A 85 8 9 85 86 15 85 87 8 85 35A 9 85 36A 8 85 35A 87 85 15 8 85 35A 36A 85 18 9 85 35A 15 85 18 87 85 14 9 85 18 36A 85 14 87 85 18 15 85 14 36A 85 74 9 85 14 15 85 74 87 34A 1 5 85 74 36A 34A 8 9 85 74 15 34A 87 8 85 75 9 34A 36A 8 (EC-33720, R307)
WSES-FSAR-UNIT-3 TABLE 10.4.9B-3 (Sheet 3 of 4) Revision 307 (07/13)
(EC-33720, R307)
CONTINUED HISTORICAL INFORMATION MINIMAL CUT SETS-CASE 1
34A 15 8 34A 35A 36A 34A 18 9 34A 35A 15 34A 18 87 34A 14 9 34A 18 36A 34A 14 87 34A 18 15 34A 14 36A 34A 74 9 34A 14 15 34A 74 87 13 1 5 34A 74 36A 13 8 9 34A 74 15 13 87 8 34A 75 9 13 36A 8 34A 75 87 13 15 8 34A 75 36A 13 18 9 34A 75 15 13 18 87 34A 94 9 13 18 36A 34A 94 87 13 18 15 34A 94 36A 13 74 9 34A 94 15 13 74 87 34A 95 9 13 74 36A 34A 95 87 13 74 15 34A 95 36A 13 75 9 34A 95 15 13 75 87 34A 86 9 13 75 36A 34A 86 87 13 75 15 34A 86 36A 13 94 9 34A 86 15 13 94 87 34A 35A 9 13 94 36A 34A 35A 87 13 94 15 (EC-33720, R307)
WSES-FSAR-UNIT-3 TABLE 10.4.9B-3 (Sheet 4 of 4) Revision 307 (07/13)
(EC-33720, R307)
CONTINUED HISTORICAL INFORMATION MINIMAL CUT SETS-CASE 1
13 95 9 13 95 87 13 95 36A 13 95 15 13 86 9 13 86 87 13 86 36A 13 86 15 13 35A 9 13 35A 87 13 35A 36A 13 35A 15 13 14 9 13 14 87 13 14 36A 13 14 15 43 92 OE1 43 90 OEI 43 64 66 43 64 67 43 65 66 43 65 67 42 OEI 93 42 91 OE1 42 68 70 42 68 71 42 69 70 42 69 71 17 42 9 17 42 87 17 42 36A 17 42 15 16 43 7 16 43 85 16 43 34A 16 43 13 36B 1 5 36B 1 6 35B 6 2 35B 6 5 35B 1 5 35B 72 73 35B 72 40 35B 39 73 35B 39 40 34B 5 2 34B 6 2 END OF HISTORICAL INFORMATION (EC-33720, R307)
WSES-FSAR-UNIT-3 TABLE 10.4.9B-4 (Sheet 1 of 5) Revision 307 (07/13)
(EC-33720, R307)
START OF HISTORICAL INFORMATION MINIMAL CUT SETS CASE 2
ME1 1 2 87 6 2 42 43 87 7 8 36B 9 81 6 2 36B 87 81 7 8 36B 81 36A 6 2 36B 36A 36A 7 8 36B 15 15 6 2 35B 8 157 8 35B 18 18 7 9 35B 74 18 87 7 35B 75 18 81 7 35B 94 18 36A 7 35B 95 18 15 7 35B 86 74 7 9 35B 35A 74 87 7 35B 14 74 81 7 34B 7 74 36A 7 34B 85 74 15 7 34B 80 75 7 9 34B 34A 75 87 7 34B 13 75 81 7 92 OE1 93 75 36A 7 92 91 OE1 75 15 7 90 OE1 93 94 7 9 90 91 OE1 94 87 7 9 6 2 94 81 7 7 1 5 94 36A 7 7 8 9 94 15 7 (EC-33720, R307)
WSES-FSAR-UNIT-3 TABLE 10.4.9B-4 (Sheet 2 of 5) Revision 307 (07/13)
(EC-33720, R307)
CONTINUED HISTORICAL INFORMATION MINIMAL CUT SETS - CASE 2
95 7 9 85 18 81 85 35A 9 95 87 7 85 18 36A 85 35A 87 95 81 7 85 18 15 85 35A 81 95 36A 7 85 74 9 85 35A 36A 95 15 7 85 74 87 85 35A 15 86 7 9 85 74 81 85 14 9 86 87 7 85 74 36A 85 14 87 86 81 7 85 74 15 85 14 81 86 36A 7 85 75 9 85 14 36A 86 15 7 85 75 87 85 14 15 35A 7 9 85 75 81 80 1 5 35A 87 7 85 75 36A 80 8 9 35A 81 7 85 75 15 80 87 8 35A 36A 7 85 94 9 80 36A 8 35A 15 7 85 94 87 80 15 8 14 7 9 85 94 81 80 18 9 14 87 7 85 94 36A 80 18 87 14 81 7 85 94 15 80 18 36A 14 36A 7 85 95 9 80 18 15 14 15 7 85 95 87 80 74 9 85 1 5 85 95 81 80 74 87 85 8 9 85 95 36A 80 74 36A 85 87 8 85 95 15 80 74 15 85 81 8 85 86 9 80 75 9 85 36A 8 85 86 87 80 75 87 85 15 8 85 86 81 85 18 9 85 86 36A 85 18 87 85 86 15 (EC-33720, R307)
WSES-FSAR-UNIT-3 TABLE 10.4.9B-4 (Sheet 3 of 5) Revision 307 (07/13)
(EC-33720, R307)
CONTINUED HISTORICAL INFORMATION MINIMAL CUT SETS - CASE 2
80 75 36A 34A 75 36A 80 75 15 34A 75 15 80 94 9 34A 94 9 80 94 87 34A 94 87 80 94 36A 34A 94 81 80 94 15 34A 94 36A 80 95 9 34A 94 15 80 95 87 34A 95 9 80 95 36A 34A 95 87 80 95 15 34A 95 81 80 86 9 34A 95 36A 80 86 87 34A 95 15 80 86 36A 34A 86 9 80 86 15 34A 86 87 80 35A 9 34A 86 81 80 35A 87 34A 86 36A 80 35A 36A 34A 86 15 80 35A 15 34A 35A 9 80 14 9 34A 35A 87 80 14 87 34A 35A 81 80 14 36A 34A 35A 36A 80 14 15 34A 35A 15 34A 1 5 34A 14 9 34A 8 9 34A 14 87 34A 87 8 34A 14 81 34A 81 8 34A 14 36A 34A 36A 8 34A 14 15 34A 15 8 13 1 5 34A 18 9 13 8 9 34A 18 87 13 87 8 34A 18 81 13 81 8 34A 18 36A 13 36A 8 34A 18 15 13 15 8 34A 74 9 13 18 9 34A 74 87 13 18 87 34A 74 81 13 18 81 34A 74 36A 13 18 36A 34A 74 15 34A 75 9 34A 75 87 34A 75 81 (EC-33720, R307)
WSES-FSAR-UNIT-3 TABLE 10.4.9B-4 (Sheet 4 of 5) Revision 307 (07/13)
(EC-33720, R307)
CONTINUED HISTORICAL INFORMATION MINIMAL CUT SETS - CASE 2
13 18 15 13 35A 81 13 74 9 13 35A 36A 13 74 87 13 35A 15 13 74 81 13 14 9 13 74 36A 13 14 87 13 74 15 13 14 81 13 75 9 13 14 36A 13 75 87 13 14 15 13 75 81 43 92 OE1 13 75 36A 43 90 OE1 13 75 15 43 64 66 13 94 9 43 64 67 13 94 87 43 65 66 13 94 81 43 65 67 13 94 36A 42 OE1 93 13 94 15 42 91 OE1 13 95 9 42 68 70 13 95 87 42 68 71 13 95 81 42 69 70 13 95 36A 42 69 71 13 95 15 17 42 9 13 86 9 17 42 87 13 86 87 17 42 36A 13 86 81 17 42 15 13 86 36A 17 42 81 13 86 15 16 43 7 13 35A 9 16 43 85 13 35A 87 16 43 34A 16 43 13 16 43 80 36B 1 5 36B 1 6 35B 6 2 35B 6 5 35B 1 5 35B 72 73 35B 72 40 35B 39 73 35B 39 40 34B 5 2 34B 6 2 (EC-33720, R307)
WSES-FSAR-UNIT-3 TABLE 10.4.9B-4 (Sheet 5 of 5) Revision 307 (07/13)
(EC-33720, R307)
CONTINUED HISTORICAL INFORMATION MINIMAL CUT SETS - CASE 2
34B 90 91 OE1 36B 43 92 OE1 8 43 90 OE1 18 43 64 66 74 43 64 67 75 43 65 66 94 43 65 67 95 42 OE1 93 86 42 91 OEI 35A 42 68 70 14 42 68 71 ME1 42 69 70 2 1 42 69 71 2 6 17 92 OE1 5 1 17 90 OE1 5 6 17 64 66 72 73 17 64 67 72 40 17 65 66 39 73 17 65 67 39 40 16 OE1 93 42 43 16 91 OE1 17 42 16 68 70 16 43 16 68 71 16 17 16 69 70 92 OE1 93 16 69 71 92 91 OE1 90 OE1 93 END OF HISTORICAL INFORMATION (EC-33720, R307)
WSES-FSAR-UNIT-3 Revision 307 (07/13)
(EC-33720, R307)
START OF HISTORICAL INFORMATION TABLE 10.4.9B-5 HAS BEEN DELETED.
END OF HISTORICAL INFORMATION (EC-33720, R307)
WSES-FSAR-UNIT-3 TABLE 10.4.9B-6 (Sheet 1 of 6) Revision 307 (07/13)
(EC-33720, R307)
START OF HISTORICAL INFORMATION BASIC EVENT CAUSES AND PROBABILITIES
Basic Probability On Event Description Cause Demand (Ref)
- 1. Manual Valve 1 Closed Plugging 1 x 10
-4 (1) Random Operator Error 3.8 x 10
-4 (2) _________________
Total 4.8 x 10
-4
- 2. Manual Valve 2 Closed Plugging 1 x 10
-4 (1) Random Operator Error 3.8 x 10
-4 (2) _________________
Total 4.8 x 10
-4
- 5. Manual Valve 5 Closed Plugging 1 x 10
-4 (1) _________________
Total 1.0 x 10
-4
- 6. Manual Valve 6 Closed Plugging 1 x 10
-4 (1) _________________
Total 1.0 x 10
-4
- 7. Manual Valve 7 Closed Plugging 1 x 10
-4 (1) _________________
Total 1.0 x 10
-4
- 8. Manual Valve 8 Closed Plugging 1 x 10
-4 (1) _________________
Total 1.0 x 10
-4
- 9. Manual Valve 9 Closed Plugging 1 x 10
-4 (1) _________________
Total 1.0 x 10
-4
- 13. Manual Valve 13 Closed Plugging 1 x 10
-4 (1) (see also ME1) _________________
Total 1 x 10
-4 (EC-33720, R307)
WSES-FSAR-UNIT-3 TABLE 10.4.9B-6 (Sheet 2 of 6) Revision 307 (07/13)
(EC-33720, R307)
CONTINUED HISTORICAL INFORMATION BASIC EVENT CAUSES AND PROBABILITIES
Basic Probability On Event Description Cause Demand (Ref)
- 14. Manual Valve 14 Closed Plugging 1 x 10
-4 (1) ______________
Total 1 x 10
-4
- 15. Manual Valve 15 Closed Plugging 1 x 10
-4 (1) (see also ME1)
______________
Total 1 x 10
-4
- 16. Manual Valve 16 Closed Plugging 1 x 10
-4 (1) (see also ME1) -
______________
Total 1 x 10
-4
- 17. Manual Valve 17 Closed Plugging 1 x 10
-4 (1) (see also ME1) -
______________
Total 1 x 10
-4
- 18. Manual Valve 18 Closed Plugging 1 x 10
-4 (1) ______________
Total 1 x 10
-4 34A. Check Valve 34 Closed Mechanical Binding 1 x 10
-4 (1) In Repair 2.1 x 10
-3 (2) _______________
Total 2.2 x 10
-3 34B. Check Valve 34 Open Mechanical Binding 1 x 10
-4 (1) 35A. Check Valve 35 Closed Mechanical Binding 1 x 10
-4 (1) In Repair 2.1 x 10
-3 (2) _______________
Total 2.2 x 10
-3 (EC-33720, R307)
WSES-FSAR-UNIT-3 TABLE 10.4.9B-6 (Sheet 3 of 6) Revision 307 (07/13)
(EC-33720, R307)
CONTINUED HISTORICAL INFORMATION BASIC EVENT CAUSES AND PROBABILITIES
Basic Probability On Event Description Cause Demand (Ref)
35B. Check Valve 35 Open Mechanical Binding 1 x 10
-4 (1) 36A. Check Valve 36 Closed Mechanical Binding 1 x 10
-4 (1) In Repair 2.1 x 10
-3 _______________
Total 2.2 x 10
-3 36B. Check Valve 36 Open Mechanical Binding 1 x 10
-4 (1)
- 39. Check Valve 39 Closed Mechanical Binding 1 x 10
-4 1)
- 40. Check Valve 40 Closed Mechanical Binding 1 x 10
-4 (1)
- 42. Check Valve 42 Closed Mechanical Binding 1 x 10
-4 (1)
- 43. Check Valve 43 Closed Mechanical Binding 1 x 10
-4 (1)
- 64. Air Op Valve 64 Closed Mechanical Binding 3 x 10
-4 (1) Control Circuit Fault (1) ____________
Total 3 x 10
-4
- 65. Air Op Valve 65 Closed Mechanical Binding 3 x 10
-4 (1) Control Circuit Fault (1) ____________
Total 3 x 10
-4
- 66. Air Op Valve 66 Closed Mechanical Binding 3 x 10
-4 (1) Control Circuit Failure (1) ____________
Total 3 x 10
-4
- 67. Air Op Valve 67 Closed Mechanical Binding 3 x 10
-4 (1) Control Circuit Failure (1) ____________
Total 3 x 10
-4
- 68. Air Op Valve 68 Closed Mechanical Binding 3 x 10
-4 (1) Control Circuit Failure (1) ____________
Total 3 x 10
-4 (1) (EC-33720, R307)
WSES-FSAR-UNIT-3 TABLE 10.4.9B-6 (Sheet 4 of 6) Revision 307 (07/13)
(EC-33720, R307)
CONTINUED HISTORICAL INFORMATION BASIC EVENT CAUSES AND PROBABILITIES
Basic Probability On Event Description Cause Demand (Ref)
- 69. Air Op Valve 69 Closed Mechanical Binding 3 x 10
-4 (1) Control Circuit Failure (1) _____________
Total 3 x 10
-4
- 70. Air Op Valve 70 Closed Mechanical Binding 3 x 10
-4 (1) Control Circuit Failure (1) _____________
Total 3 x 10
-4
- 71. Air Op Valve 71 Closed Mechanical Binding 3 x 10
-4 (1) Control Circuit Failure (1) _____________
Total 3 x 10
-4
- 72. Motor Op Valve 72 Closed Mechanical Binding 1 x 10
-3 (1) Plugging Contribution 1 x 10
-4 (1) Control Circuit Failure 2 x 10
-3 (1) _____________
Total 3.1 x 10
-3
- 73. Motor Op Valve 73 Closed Mechanical Binding 1 x 10
-3 (1) Plugging Contribution 1 x 10
-4 (1) Control Circuit Failure 2 x 10
-3 (1) _____________
Total 3.1 x 10
-3 74. Motor Op TDP Steam Stop Valve Closed Random Operator Error 5 x 10
-4 (2)
- 75. Hydr Op TDP Governor Mechanical Binding 3 x 10
-4 (1) Valve Closed Control Circuit Failure 6 x 10
-3 (1) _____________
Total 6.3 x 10
-3
-2 (3) Failure "A" DG in Repair 0.64 x 10
-2 (1) _____________
Total 3.64 x 10
-2 (EC-33720, R307)
WSES-FSAR-UNIT-3 TABLE 10.4.9B-6 (Sheet 5 of 6) Revision 307 (07/13)
(EC-33720, R307)
CONTINUED HISTORICAL INFORMATION BASIC EVENT CAUSES AND PROBABILITIES
Basic Probability On Event Description Cause Demand (Ref)
-2 (3) Failure "B" DG in Repair 0.64 x 10
-2 (1) _______________
Total 3.64 x 10
-2
- 85. "A" MDP Failure to Mechanical Fault 1 x 10
-3 (1) Start Control Circuit Fault 4 x 10
-3 (1) Pump in Repair 2.1 x 10
-3 (2) _______________
Total 7.1 x 10
-3
- 86. TDP Failure To Start Mechanical Fault 1 x 10
-3 (1) Pump Repair 2.1 x 10
-3 (2) _______________
Total 3.1 x 10
-3
- 87. "B" MDP Failure To Mechanical Fault 1 x 10
-3 (1) Start Control Circuit Fault 4 x 10
-3 (1) Pump In Repair 2.1 x 10
-3 _______________
Total 7.1 x 10
-3
- 90. EFAS 1 "A" Not Generated (Not Specified) 7 x 10
-3 (1)
- 91. EFAS 2 "A" Not Generated (Not Specified) 7 x 10
-3 (1)
- 92. EFAS 1 "B" Not Generated (Not Specified) 7 x 10
-3 (1)
- 93. EFAS 1 "B" Not Generated (Not Specified) 7 x 10
-3 (1)
- 94. Spurious TDP Overspeed (Not Specified) 7 x 10
-3 (1) Signal
- 95. TDP Speed Controller (Not Specified) 7 x 10
-3 (1) Failure
ME1 See Subsection Maintenance Error 5 x 10
-6 (1) (2) 10.4.9B.5.1.1
OEI Operator failure to Operator Error 1 x 10
-2 (1) back up automatic EFW actuation (EC-33720, R307)
WSES-FSAR-UNIT-3 TABLE 10.4.9B-6 (Sheet 6 of 6) Revision 307 (07/13)
(EC-33720, R307)
CONTINUED HISTORICAL INFORMATION BASIC EVENT CAUSES AND PROBABILITIES
NOTES: (1) Letter, D Ross (NRC) to All Pending OL Applicants of W and CE NSSS Designs, dated 3/10/80.
(2) Subsection 10.4.9B.5.1.1.
(3) WASH-1400
END OF HISTORICAL INFORMATION (EC-33720, R307)
WSES-FSAR-UNIT-3 TABLE 10.4.9B-7 Revision 307 (07/13)
(EC-33720, R307)
START OF HISTORICAL INFORMATION EFS VALVES SUBJECT TO ASM E SECTION XI TESTING
LP&L UNID NO. / EBASCO NO.
64 EFW-224A/2FW-V851B
65 EFW-228A/2FW-V848A
66 EFW-223A/2FW-V852A
67 EFW-229A/2FW-V847A
68 EFW-223B/2FW-V854B
69 EFW-229B/2FW-V849A
70 EFW-224B/2FW-V853A
71 EFW-228B/2FW-V850B
72 MS-401A/2MS-V611A
73 MS-40IB/2MS-V612B 74 MS-416
- 75 MS-417
31 EFW-204A/3FW-VI507-2
32 EFW-204A/B/3FW-VI517
33 EFW-204B/3FW-VI507-1
34 EFW-207A/3FW-V601A
35 EFW-207A/B/3FW-V603A/B
36 EFW-207B/3FW-V602B
39 MS-402A/3MS-V676A
40 MS-402B/3MS-V677B
42 EFW-2191A/3FW-VI541A
43 EFW-219IB/3FW-VI542B
- For the Reliability Study, the purpose of assu ming a quarterly test is to ensure that the valves are operable (or in the correct position) at least quarterly. These valves are exempt from ASME Section XI testing, however, they are ve rified operable monthly during the EFW pump test.
Therefore, the Reliability Study was conservative.
END OF HISTORICAL INFORMATION (EC-33720, R307)
WSES-FSAR-UNIT-3 TABLE 10.4.9B-8 (Sheet 1 of 5) Revision 307 (07/13) (EC-33720, R307)
START OF HISTORICAL INFORMATION
SUMMARY
OF TEST AND MAINTENANCE CONTRIBUTIONS TO COMPONENT AVAILABILITY Other Tests Testing of Component Maintenance on Component Involving Components Other Maintenance Acts Involving Unavailabitity Unavailability Which Contribute Components Which Contribute Component Frequency From Test Frequency From Maint. To Unavailability To Unavailability
- 1. Valve 1 - Manual - - - - None None planned or anticipated EFW-102B/3CO-V111B2.
- 2. Valve 2 - Manual - - - - None None plained or anticipated EFW-102A/3CO-V110A
- 7. Valve 7 - Manual - - - - None "A MDP maintenance; Valve 34 EFW-106A/3CD-V112A maintenance
- 8. Valve 8 - Manual - - - - None TDP maintenance; Valve 35 EFW-106A/B/3CD-V114 A/B Maintenance
- 9. Valve 9 - Manual - - - - None "B" MDP mintenance; valve 36 EFW-106B/3CD-V113B maintenance
- 13. Valve 13 - Manual - - - - None "A" MDP maintenance; Valve 34 EFW-211A/3FW-604A maintenance Prestart-up Feedwater Cleaning
- 14. Valve 14 - Manual - - - - None TDP mintenance; Valve 35 EFW-211A/B/3FW-606A/B maintenance
- 15. Valve 15 - Manual - - - - None "B" MPD maintenance; Valve 36 EFw-211B/3FW-V605B Prestart-up Feedwater Cleaning
- 16. Valve 16 - Manual - - - - None Prestart-up Feedwater Cleaning EFW-215A/3FW-V608 (EC-33720, R307)
WSES-FSAR-UNIT-3 TABLE 10.4.9B-8 (Sheet 2 of 5) Revision 307 (07/13) (EC-33720, R307)
CONTINUED HISTORICAL INFORMATION
SUMMARY
OF TEST AND MAINTENANCE CONTRIBUTIONS TO COMPONENT AVAILABILITY Other Tests Testing of Component Maintenance of Component Involving Components Other Maintenance Acts Involving Component Unavailability Unavailability Which COntribute Components Which Contribute Frequency From Test Frequency From Maint. to Unavailability to Unavailability
- 17. Valve 17 - Manual - - - - None Prestartup Feedwater Cleaning EFW-215B/3FW-V609
- 18. Valve 18 - Manual - - - - None TDP maintenance; Valve 35 maintenance
- 34. Valve 34 Check quarterly 0 Note 2 - Not Applicable Not Applicable EFW-207A/3FW-601A
- 35. Valve 35 - Check quarterly 0 Note 2 - Not Applicable Not Applicable EFW-207A/B/3FW-603A/B
- 36. Valve 36 - Check quarterly 0 Note 2 - Not Applicable Not Applicable EFW-207A/3FW-602B
- 39. Valve 39 -Check quarterly 0 Note 1 - Not Applicable Not Applicable
- 40. Valve 40 - Check quarterly 0 Note 1 - Not Applicable Not Applicable
- 42. Valve 42 - Check quarterly 0 Note 1 - Not Applicable Not Applicable EFW-VI541A
- 43. Valve 43 - Check quarterly 0 Note 1 - Not Applicable Not Applicable EFW-Vl542B
- 64. Valve 64 - Air quarterly 0 Note 1 0 None -
EFW-224A/2FW-V851B
- 65. Valve 65 - Air quarterly 0 Note 1 0 None -
EFW-22BA/2FW-V848A
- 66. Valve 66 - Air quarterly 0 Note 1 0 None -
EFW-223A/2FW-V852A
- 67. Valve 67 - Air quarterly 0 Note 1 0 None -
EFW-229A/2FW-V847B
- 68. Valve 68 - Air quarterly 0 Note 1 0 None -
EFW-223B/2FW-V8540 (EC-33720, R307)
WSES-FSAR-UNIT-3 TABLE 10.4.9B-8 (Sheet 3 of 5) Revision 307 (07/13) (EC-33720, R307)
CONTINUED HISTORICAL INFORMATION
SUMMARY
OF TEST AND MAINTENANCE CONTRIBUTIONS TO COMPONENT AVAILABILITY Other Tests Testing of Component Maintenance of Component Involving Components Other Maintenance Acts Involving Unavailability Unavailability Which COntribute Components Which Contribute Component Frequency From Test Frequency From Maint. to Unavailability to Unavailability
- 69. Valve 69 - Air quarterly 0 Note 1 0 None -
EFW-220B/2FW-V849A
- 70. Valve 70 - Air quarterly 0 Note 4 0 None -
EFW-224B/2FW-V853A
- 71. Valve 71 - Air quarterly 0 Note 1 0 None -
EFW-228B/2FW-850B
- 72. Valve 72 - Motor quarterly 0 Note 1 0 None -
- 73. Valve 73 - Motor quarterly 0 Note 1 0 None -
- 74. Valve 74 - Motor quarterly 0 Note 2 Section 10.4.9B.5.1.1 None - *
- 75. Valve 75 - Hydraulic quarterly 0 Note 2 Section 10.4.9B.5.1.1 None None *
- 80. "A" 4kV Power monthly 0 Note 2 Section 10.4.9B.5.1.1 None None (SA-DG)
- 81. "B" 4kV Power monthly 0 Note 2 Section 10.4.9B.5.1.1. None None (SA-DG)
- 85. "A" MDP monthly 0 Note 2 Section 10.4.9B.5.1.1. None None
- 86. TDP monthly 0 Note 2 Section 10.4.9B.5.1.1 None None
- 87. "B" MDP monthly 0 Note 2 Section 10.4.9B.5.1.1 None None
- 90. EFAS 1 "A" Logic monthly 0 Note 2 Note 3 None None
(DRN 00-786, R11-A)
- For the Reliability Study, the purpose of assuming a quarterly test is to ensure that the valves are operable (or in the correct position) at least quarterly. These valves are exempt frm ASME Sectim Xi testing, however, they are verified operable monthly during the EFW pump test. Therefore, the Reliability Study was conservative. (DRN 00-786, R11-A
- EC-33720, R307)
WSES-FSAR-UNIT-3 TABLE 10.4.9B-8 (Sheet 4 of 5) Revision 307 (07/13) (EC-33720, R307)
CONTINUED HISTORICAL INFORMATION
SUMMARY
OF TEST AND MAINTENANCE CONTRIBUTIONS TO COMPONENT AVAILABILITY
Other Tests Testing of Component Maintenance of Component Involving Components Other Maintenance Acts Involving Unavailability Unavailability Which COntribute Components Which Contribute Component Frequency From Test Frequency From Maint. to Unavailability to Unavailability
- 91. EFAS 2 "A" Logic monthly 0 Note 2 Note 3 None None
- 92. EFAS 1 "B" Logic monthly 0 Note 2 Note 3 None None
- 93. EFAS 2 "B" Logic monthly 0 Note 2 Note 3 None None
- 94. TDP Overspeed See 86 0 Note 2 Note 3 None None Trip
- 95. TDP Speed See 86 0 Note 2 Note 3 None None Control (EC-33720, R307)
WSES-FSAR-UNIT-3 TABLE 10.4.9B-8 (Sheet 5 of 5) Revision 307 (07/13) (EC-33720, R307)
CONTINUED HISTORICAL INFORMATION
SUMMARY
OF TEST AND MAINTENANCE CONTRIBUTIONS TO COMPONENT AVAILABILITY
NOTES:
- 1. Valve cannot be maintained during power operation due to connection with pressurized system.
- 2. Component maintained during power operat ion only if results of periodic test unsatisfactory.
- 3. Maintenance on single channel EFAS Logic does not render Logic inoperable.
END OF HISTORICAL INFORMATION (EC-33720, R307)
WSES-FSAR-UNIT-3 TABLE 10.4.9B-9 Revision 307 (07/13) (EC-33720, R307)
START OF HISTORICAL INFORMATION DOMINANT CUT SETS - CASE 1 42.1a x 10-5
_____________________________________________________________________________________
Cut Set Events i a a a i _____________________________________________________________________________________
1 ME1 5x10
-6 35.2% 5 36B 87 7.1x10
-7 5.0 11 35B 75 6.3x10
-7 4.4 12 35B 94 7.0x10
-7 4.9 26.4 13 35B 95 7.0x10
-7 4.9 14 35B 86 3.1x10
-7 2.2 18 34B 85 7.1x10
-7 5.0 21 92 93 E1 4.9x10 -7 3.5 22 91 92 E1 4.9x10 -7 3.5 14.0 23 90 93 E1 4.9x10 -7 3.5 24 90 91 E1 4.9x10 -7 3.5 80 85 75 87 3.2x10
-7 2.3 7.3 84 85 94 87 3.5x10
-7 2.5 88 85 95 87 3.5x10
-7 2.5 TOTAL 82.9%
END OF HISTORICAL INFORMATION (EC-33720, R307)
WSES-FSAR-UNIT-3 TABLE 10.4.9B-10 Revision 307 (07/13) (EC-33720, R307)
START OF HISTORICAL INFORMATION DOMINANT CUT SETS - CASE 2 97.3a x 10-5
____________________________________________________________________________________
Cut Set Events i a a a i ____________________________________________________________________________________ 1 ME1 5.0x10
-6 12.6% 5 36B 87 7.1x10
-7 1.8 8 36B 81 3.64x10
-6 9.2 12 35B 75 6.30x10
-7 1.6 13 35B 94 7.0x10
-7 1.8 27.2 14 35B 95 7.0x10
-7 1.8 19 34B 85 7.1xl0
-7 1.8 22 34B 80 3.64x10
-6 9.2 23 92 93 E1 4.9x10 -7 1.2 24 91 92 E1 4.9x10 -7 1.2 4.8 25 90 93 E1 4.9x10 -7 1.2 26 90 91 E1 4.9x10 -7 1.2 98 85 75 81 1.63x10
-6 4.1 103 85 94 81 1.81x10
-6 4.6 108 85 95 81 1.81x10
-6 4.6 113 85 86 81 8.01x10
-7 2.0 30.6 233 80 75 87 1.63x10
-6 4.1 238 80 94 87 1.81x10
-6 4.6 243 80 95 87 1.81x10
-6 4.6 248 80 86 87 8.01x10
-7 2.0 TOTAL 75.2%
END OF HISTORICAL INFORMATION (EC-33720, R307)
WSES-FSAR-UNIT-3 TABLE 10.4.9B-11 Revision 307 (07/13) (EC-33720, R307)
START OF HISTORICAL INFORMATION DOMINANT CUT SETS - CASE 3
63.2a x 10-2
____________________________________________________________________________________
Cut Set Events i a a a i ____________________________________________________________________________________
6 75 6.3x10
-3 24.0% 7 94 7.0x10
-3 26.6 8 95 7.0x10
-3 26.6 9 86 3.1x10
-3 11.8 10 35A 2.2x10
-3 8.4 __________
TOTAL 97.4%
END OF HISTORICAL INFORMATION (EC-33720, R307)