ML20207E696
| ML20207E696 | |
| Person / Time | |
|---|---|
| Site: | Waterford  |
| Issue date: | 03/03/1999 |
| From: | Dugger C ENTERGY OPERATIONS, INC. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| W3F1-99-0019, W3F1-99-19, NUDOCS 9903110048 | |
| Download: ML20207E696 (18) | |
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O Entergy Operatisno,Inc.
Killona. LA 700GG 0751 Tel 504 739 6060 Charles M. Dugger e Prescent. Operanons W3F1-99-0019 A4.05 PR March 3,1999 U.S. Nuclear Regulatory Commission Attn: Document Control Desk
. Washington, D.C. 20555
Subject:
Waterford 3 SES Docket No. 50-382 License No. NPF-38 FSAR Change Request EDG Fuel Oil Storage Capacity Unresolved Safety Question Gentlemen:
In accordance with 10CFR50.90, Entergy is hereby proposing to revise Final Safety Analysis Report (FSAR) Section 9.5.4.1. The revision changes this section of the FSAR to explicitly list the Waterford 3 deviations from ANSI N195-1976. This change also revises the Waterford 3 commitments discussed in a letter to the Nuclear Regulatory Commission (NRC) from C.M. Dugger, dated July 15,1997.
In the July 15,1997 letter, Entergy committed to make facility changes, prior to Cycle
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10, to address the fuel oil storage issues at Waterford 3. This letter was in response
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to NRC Inspection Report 50-382/97-10 dated June 16,1997, which identified issues
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with the Waterford 3 Emergency Diesel Generator (EDG) fuel oil storage system with respect to ANSI N195-1976. The July 15,1997 letter also committed to maintaining contingencies to address these issues until permanent solutions are implemented.
A Upon further review of the non-compliances to AN31 N195-1976, Entergy concluded that increasing the fuel oil storage capacity at Waterford 3 has a negligible benefit on safety. Therefore, Entergy is proposing to revise the Waterford 3 FSAR to explicitly identify the deviations from ANSI N195-1976. Entergy evaluated these proposed FSAR changes in accordance with 10CFR50.59 and determined that these 000088 9903110048 990303 7
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FSAR Change Request i
4 EI)G Fuel. Oil Storage Capacity Unresolved. Safety Question l
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March 3,1999 proposed changes constitute an Unreviewed Safety Question (USQ).. Therefore, in accordance with 10CFR50.59, Entergy is requesting NRC Staff approval of these FSAR changes prior to implementation.
Entergy requests NRC Staff review and approval of this change, as supported by the '
attachments to this letter, by July 31,1999. In the interim, Entergy will continue to~
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l maintain the contingencies set forth in the July 15,1997 letter. If the proposed j
. FSAR changes are approved, Entergy will consider the above commitment closed and discontinue all contingencies.
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This proposed change has been evaluated in accordance with 10CFR50.91(a)(1),
using the criteria in 10CFR50.92(c), and it has been determined that this request -
involves no significant hazard considerations. The bases for these determinations are described in the attached enclosure.
J Should you have any questions or comments concerning this request, please contact i
Early Ewing at (504) 739-6242 or Charles DeDeaux at (504) 739-6531.
Very)truly yours,
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r C.M. Dugger Vice President, Operations Waterford 3 CMD/CED/ssf Attachments:
Affidavit Description of Proposed FSAR Change Attachment A: Existing FSAR Section Attachment B: Proposed FSAR Section Attachment C: Probabilistic Safety Assessment cc:
E.W. Merschoff (NRC Region IV), C.P. Patel (NRC-NRR),
J. Smith, N.S. Reynolds, NRC Resident inspectors Office, Administrator Radiation Protection Division (State of Louisiana),
American Nuclear Insurers a
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UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION--
In'the matter of
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Entergy Operations, Incorporated
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Docket No. 50-382 Waterford 3 Steam Electric Station
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Charles' Marshall Dugger, being duly sworn, hereby_ deposes and says that he is Vice President Operations - Waterford 3 of Entergy Operations, Incorporated; that he is duly authorized to sign and file with the Nuclear Regulatory Commission the attached Final i
Safety Analysis Report Change Request; that he is familiar with the content thereof; and that the matters set forth therein are true and correct to the best of his knowledge, information and belief.
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8' Charles Marshall Dugger -
Vice President Operations - Waterford 3.
l STATE OF LOUISlANA
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PARISH OF ST. CHARLES
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1 Subscribed and sworn to before me, a Notary Public in and for the Parish and State above named this 34/
day of M{ Locle
.1999.
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Notary Public My Commissien expires k d;
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. DESCRIPTION AND NO SIGNIFICANT HAZARDS CONSIDERATION OF THE PROPOSED CHANGE TO THE WATERFORD 3 FSAR.
. The proposed change revises the Waterford 3 Final Safety Analysis Report Section 9.5.4.1 (Diesel Generator Fuel Oil Storage and Transfer Systems Design Basis) to
' identify the specific Waterford 3 deviations from ANSI N195-1976 (Fuel Oil Systems for i:
. Standby Diesel Generator).
Existing FSAR Section :
See Attachment A Proposed FSAR Section See Attachment B
Background
Waterford 3 currently has two ASME Section Ill, Class 3, Fuel Oil Storage Tanks (FOSTs), one for each Emergency Diesel Generator (EDG). Each EDG FOST has a useable capacity of 40,959 gallons. The Technical Specifications require at least 38,760 gallons for each EDG FOST.' The fuel oil from each EDG FOST is automatically pumped to a 613 gallon EDG fuel oil feed tank via a transfer pump. Each feed tank is filled from its own EDG FOST by its own transfer pump, but normally closed cross-tie valves are provided to enable either pump to fill either or both feed tanks from either storage tank. The fuel is gravity fed to the EDG engine, via a connection on the bottom of the EDG feed tanks, through two strainers and filters connected in parallel.
American National Standards Institute (ANSI) N195-1976 is the standard applicable to fuel oil systems for standby diesel generators. It requires the Waterford 3 EDG FOSTs to have a seven day fuel oil storage capacity based on either a seven day time dependent load calculation plus 10% margin, or a more conservative calculation method which assumes the EDG is at continuous rated capacity for seven days. Both methods require an additional amount of fuel oil be added for testing.
The minimum allowed volume of EDG fuel oil that can be stored in the Waterford 3 EDG FOSTs (per existing Technical Specifications) is sufficient to operate each EDG for seven days (utilizing the time dependent load calculation method) with an approximate 1% margin (testing amount not included). However, this amount does not meet ANSI N195-1976 requirements for a 10% margin plus an amount for testing. In a -
letter from C.M. Dugger, dated July 15,1997, Entergy notified the NRC Staff that Waterford 3 does not meet the requirements of ANSI N195. This letter was in response to NRC Staff Inspection Report 50-382/97-10, dated June 16,1997. Additionally, the letter provided the compensatory measures to be taken by Entergy until the fuel oil 1
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i storage issues at Waterford 3 are addressed. The letter also contained a commitment
. for E,ntergy to resolve the EDG fuel oil issues prior to Cycle 10 operation.
A thorough review of ANSI N195-1976 indicates there are additional areas of noncompliance with the Standard. ANSI'N195-1976 requires the feed tank suction to i
be from above the bottom of the tank, the feed tank overflow to be directed to the i
FOST, and pressure indication to be provided at the discharge of the EDG fuel oil transfer pump. Waterford 3 does not comply with these ANSI N195-1976 requirements and proposes to retain the existing design for the feed tank outlet (at the tank bottom),
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' for the feed tank overflow to discharge to a floor drain (sump pump system which goes to oil separators), and to not have pressure indication at the transfer pump discharge.
As described in the following section, these deviations do not affect the capability of the fuel oil storage system to provide at least seven days of fuel oil to one EDG.
A description, justification, and No Significant Hazards Consideration Determination for
- the proposed FSAR changes to resolve the EDG fuel oil issues at Waterford 3 follows.
Description and Safety Considerations The following will be added to Waterford 3 FSAR Section 9.5.4.1.
AII safety related portions of the Waterford 3 diesel engine fuel oil storage and transfer system, are seismic Category I, safety class 3, and designed to ANSI i
Standard N195-1976, " Fuel Oil Storage System for Standby Diesel Generator,"
with the exceptions as listed below; a)
The Waterford 3 Emergency Diesel Generator (EDG) Fuel Oil Storage Tanks (FOSTs) contain a seven day fuel oil supply using the time dependent method for calculating stored fuel oil. The Waterford 3 EDG FOSTs do not contain an explicit allowance formargin.
b) '
The Wsterford 3 EDG FOSTs do not contain an explicit allowance for fuel consumption required forperiodic testing.
c)
The Waterford 3 EDG fuel oil feed tank suction is located on the bottom of the feed tank.
d)
The Waterford 3 EDG fuel oil feed tank overflow discharges to the sump i
pump system.-
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The Waterford 3 EDG fuel oil transfersystem does not have a pressure indicatorlocated at the discharge of the fuel oil transferpumps.
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. Below are the justifications for the above listed deviations.
4 a., b. Fuel Oil Volume j
ANSI N195-1976 requires a minimum margin of 10% be added to the fuel oil storage volume (seven days supply) when the volume is calculated using the time dependent load method. Waterford 3 does not meet this requirement. The c
Waterford 3 FOST capacity, required by TS, contains a seven-day supply plus
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j an approximate 1% margin. This capacity provides sufficient volume for the
- electrical loading on the EDGs for at least seven days during a loss of coolant accident with loss of offsite power which is the most limiting event. Replenishing the EDG FOST can be readily accomplished if needed because multiple diesel j
fuel oil vendors are in the vicinity of Waterford 3. Waterford 3 is located in a heavy industrial corridor of Louisiana where there are many oil refineries and oil l
storage facilities. Entergy has the capability to replenish EDG fuel oil at
- Waterford 3 by tanker truck, train, or barge. The total stored fuel oil at Waterford j
3 is sufficient to operate one EDG for seven days assuming any single active or i
passive failure. In addition the Waterford 3 fuel oil storage system contains
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crossties between the EDG FOSTs which enables either of the EDG engines to i
be supplied from either of the EDG FOSTs.
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Entergy has reviewed the fuel oil storage system at Waterford and has determined that additional EDG FOST capacity results in a negligible impact on improving safety. Entergy has concluded, based on Probabilistic Safety _
Assessment (PSA) techniques, there is no risk significance to not increasing the fuel oil capacity at Waterford 3. The basis for this conclusion is located in Attachment C.
ANSI N195-1976 requires the supply of stored fuel oil to include an explicit allowance for fuel consumption required by periodic testing. This was identified in NRC Staff Inspection Report 50-382/97-10 dated June 16,1997, which stated the required fuel oil volume in Waterford 3 FOSTs do not contain an additional amount for testing. However, the staff reviewed Amendment 92 which modified the fuel oil storage requirements to allow a lower fuel level for a short time to _
support additional testing. Therefore, although Waterford 3 does not meet the j
- ANSI-N195 requirements for the EDG FOST to contain an amount for testing,
. the NRC Staff previously reviewed this deviation.
c.- Feed Tank Suction '
ANSI N195-1976 requires the EDG feed tank suction to be from rd we the
. bottom. The EDG feed tank suction on the Waterford 3 feed tanks is on the bottom. This discrepancy was identified during a review of the Waterford 3 EDG
' fuel oil storage system against ANSI N195-1976. Operating experience at Waterford 3 has shown that there have not been any water or fi ter blockage i
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problems attributed to the bottom suction from the feed tank. The fuel oil in each
. feed tank is replenished every 31 days during the EDG monthly Surveillance Requirement (each feed tank holds approximately half the volume required for testing it's associated EDG); therefore, the probability of fuel degradation in the feed tanks is small. Blockage problems are further decreased because testing the EDG FOSTs for particulates is performed with a more conservative filter size than used in the fuel oil system (0.8 microns versus 5 microns). Also, TS require water to be removed from the feed tank (if any is found) after every EDG operation (of > 1 hr. duration) and once per 31 days, and new fuel oil to be verified to have proper water and sediment content prior to being added to the EDG FOST and once per 92 days.
- d. Feed Tank Overflow 1
ANSI N195-1976 requires the feed tank overflow to discharge back to the EDG FOST. The Waterford 3 feed tank overflow line discharges to the sump pump system via a drain. This discrepancy was also identified during a review of the Waterford 3 EDG fuel oil storage system against ANSI N195-1976. Therefore, the possibility exists that the fuel oilin the EDG FOST could be depleted if the transfer pump continued to run. However, for this to occur two safety measures t
would have to fail. The high level switch (that stops the transfer pump) and the feed tank high level alarm (that alerts the Control Room) would have to fail.
l These design features will not prevent the loss of some fuel oil; however, multiple failures would have to occur to deplete the entire contents of one EDG l
FOST. This deviation is acceptable because the concurrent failures of the feed I
tank high level switch and the feed tank high level alarm are very remote.
l Assuming conditions occurred which drained one entire EDG FOST, the other l
EDG FOST would be available to ensure seven days of EDG fuel oil is available l
fra one EDG.
- e. Pressure indication ANSI N195-1976 requires one pressure indicator to be located in the discharge of the fuel oil transfer pump. Waterford 3 does not have a pressure indicator on the discharge of the transfer pump. This discrepancy was also identified during a review of the Waterford 3 EDG fuel oil storage system against ANSI N195-1976. A pressure indicator on the discharge of the transfer pump could indicate performance degradation of the pump. The Waterford 3 transfer pumps are designed for automatic operation and are automatically started when the low level is reached in the EDG feed tanks and automatically stopped when the high level is reached. The EDG feed tanks also contain high and low level alarms and indicators in the Control Room. if a failure of the transfer pump occurred, indication would appear in the Control Room via an clarm on low feed tank level.
Entergy performs ASME Section XI inservice testing on the transfer pump once per quarter (temporary pressure instrumentation is installed on the discharge of 4
the pump to measure pump differential pressure) to verify that pump
. performance has not degraded. In addition, the transfer pun ps are functionally I
tested every month during routine testing of the EDGs.
No Significant Hazards Consideration Determination
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- The proposed change described above shall be deemed to involve a significant
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hazards consideration if there is a positive finding in any of the following areas:
1.
Will operation of the facility in accordance with this proposed change.
involve a significant increase in the probability or consequences of an accident l
previously evaluated?
Response
No j
The proposed change revises the Waterford 3 FSAR to match the current design of the Waterford 3 fuel oil storage and transfer system. The change effectively requests deviations from portions of ANSI N195-1976. None of these changes significantly increases the probability of an accident because the Emergency Diesel Generator (EDG) fuel oil system is not an initiator of any analyzed event.
i There are no accidents analyzed in the Final Safety Analysis Report (FSAR) that are initiated by the systems or components affected by these changes.
The deviation from ANSI N195-1976, which allows less than the ANSI Standard recommended volume to be stored in the existing EDG Fuel Oil Storage Tanks I
l (FOSTs) A and B, will not significantly increase the consequences of an I
' accident. Waterford 3 contains at least seven days of fuel oil in each FOST.
~ Although the Waterford 3 FOSTs do not contain a 10% margin, there are l
' numerous diesel fuel oil vendors nearby from which to obtain fuel oil. Waterford 3 also has the capability to transport EDG fuel oil from vendors by tanker truck, train, or barge. This situation ensures that Waterford 3 will have fuel oil readily available when there is a need for replenishment. Waterford 3 does not store the additional amount of fuel oil required for testing. A previous Technical l
Specification (TS) Amendment addressed the Waterford 3 FOSTs not containing enough fuel oil for testing. However, an exception to this requirement was previously approved in TS Amendment 92.
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- The request for deviation from the ANSI 'NG5-1976 requirement for the feed I
tank suction to be from above the bottom, will not increase the consequences of p
'any accident. Previous operating experience at Waterford 3 has shown that j
since initial startup there have not been any water or filter blockage problems attributed to the bottom suction from the feed tank. The fuel oil in each feed tank is replenished every 31 days during the EDG monthly Surveillance Requirement i
(SR).- Blockage problems are further minimized because testing the FOSTs for l-particulates is performed with a more conservative filter size than installed on the
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EDG engine (0.8 mx Tns versus 5 microns). Also, TS Surveillances require
. water and sediment content to be verified and if water is present, for it to be removed.
' The request for deviation from the ANSI N195-1976 requirement for the feed tank overflow to discharge to the FOST will not increase the consequences of any accident. The feed tank is equipped with design features to ensure fuel oil is not depleted due to over-filling the feed tank. The feed tank contains a high level switch that stops the transfer pump upon indication of high level and a high level alarm that alerts the Control Room of high level in the tank. A failure of both the feed tank high level switch and high level alarm occurring simultaneously is very remote. These measures will not prevent the loss of some fuel oil; however, two failures would have to occur to prevent the Control Room from being notified.
I Even if one EDG FOST were depleted because of the above failures, the other EDG FOST would be available to ensure seven days of fuel oil for one EDG.
i The request for deviation from the ANSI N195-1976 requirement to have one pressure indicator located in the discharge of the fuel oil transfer pump will not increase the consequences of any accident. A pressure indicator on the discharge of the transfer pump could indicate performance degradation of the t
l pump; however, the Waterford 3 transfer pumps are designed for automatic r
operation if a failure of the transfer pump occurred, indication would appear in the Control Room via the alarm for low feed tank level. The alarm for low feed tank level is adequate to alert the Control Room of a transfer pump malfunction.
If a transfer pump were to malfunction, the other transfer pump would be available to deliver fuel oil to operate one EDG for at least seven days. ASME Section XI testing is performed on the transfer pump once per quarter (temporary
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pressure instrumentation is installed on the discharge of the pump to measure pump differential pressure) to verify that pump performance has not degraded.
in addition, the transfer pumps are functionally tested every month during routine l
testing of the EDGs.
The requested deviations from ANSI N195-1976 do not affect the consequences of an accident because none of the requested deviations will prevent the EDG
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from having seven days of fuel oil available (without multiple failures). Therefore, l
the EDG fuel oil system will perform as required to provide sufficient fuel oil to the EDG to mitigate the consequences of design basis accidents.
Therefore, based on all the above, the proposed changes do not involve a significant increase in the probability or consequences of an accident previously evaluated.
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Will operation of the facility in accordance with this proposed change create the possibility of a new or different type of accident from any accident previously evaluated?
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. Response:
No.
The proposed change revises the Waterford 3 FSAR to match the current design of the Waterford 3 fuel oil storage and transfer system. This change is a change to a commitment, and has no effect on the current diesel fuel oil storage system or how it is operated, nor does it effect any other safety systems or components, i
or the way the plant is operated..The change does not affect any accident analysis assumptions (including a loss of offsite power) or accident analysis conclusions. Therefore,'the proposed change will not create the possibility of a new or different kind of accident from any accident previously evaluated.
3.
Wi!I operation of the facility in accordance with this proposed change l
involve a significant reduction in a margin of safety?
Response: -No i
The proposed change revises the Waterford 3 FSAR to match the current design of the Waterford 3 fuel oil storage system. Although, Waterford 3 deviates from certain ANSI N195-1976 requirements, these deviations do not result in any changes to the fuel oil storage system or accident analyses. The deviations do not affect the ability of any safety systems required to protect the multiple barriers. No accident mitigatiors are affected by the change because the amount of available fuel oil has not changed. As a result, the proposed deviations will not cause a significant decrease in the margin of safety or prevent Waterford 3 from safely shutting down. The result of using Probabilistic Safety Assessment techniques conclude that increasing the fuel oil storage capacity at Waterford 3 to comply with the ANSI requirements has no risk significance. The specif c ~
effects of the deviations on the margin of safety are addressed below.
The current TS for stored EDG fuel oil ensures there is sufficient fuel oil to operate one EDG for seven days assuming the worsi case wngle active or
' passive failure. Fuel oil is readily available due to the numbei of vendors in the vicinity of Waterford 3. Waterford 3 is also capable of replenieldng EDG fuel oil-via tanker truck, train, or barge. Therefore, this change doet, s.ot affect the supply of EDG fuel oil being maintained at Waterford 3. This supply of fuel oil is
. sufficient to power the ESF systems required to mitigate design basis accidents.
A previous TS Amendment addressed the Waterford 3 FOSTs not containing
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. enough fuel' oil for testing.
The current feed tank design with the suction from the bottom instead of on the I
side as required by ANSI N195-1976 will not significantly decrease the margin of safety. Waterford 3 has not experienced paa.calate or water accumulation in the
' feed tanks. The fuel oil in the tank is essentially turned-over every 31 days during the EDG monthly _SR, and TS Surveillances ensure water and sediment 7
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content are verified. Additionally, particulate testing is performed on the EDG -
FOSTs using a test filter with a smaller micron size than is on the engine. This I
will assure the EDG engine is not subject to failures due to particulate or water j
accumulation in the feed tanks.-
The request for deviation from the ANSI N195-1976 requirement for the feed a
tank overflow to discharge to the FOST will not significantly decrease the margin of safety. The feed tank is equipped with two safety measures that would have to fail in order to allow a loss'of EDG fuel oil due to over-filling a feed tank. A failure of these safety measures (high level switch to stop the transfer pump and '
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- a high level alarm in the feed tank) occurring simultaneously is very remote.
The request for deviation from ANSI N195-1976 to have one pressure indicator located at the discharge of the fuel oil transfer pump.will not significantly decrease the margin of safety. A pressure indicator on the discharge of the
- i transfer pump could indicate performance degradation of the pump. If a failure of the transfer pump occurred, indication would appear in the Control Room via the alarm for low feed tank level. The alarm for low feed tank is adequate to alert the control room df a transfer pump malfunction. However, if the transfer pump q
were to malfunction, the other transfer pump would be available to deliver fuel oil i
to operate one EDG for at least seven days. ASME Section XI testing is
_ performed on the transfer pump once per quarter (temporary pressure
. 1 instrumentation is' installed on the discharge of the pump to measure pump differential pressure) to verify that pump performance has not degraded. in addition, the transfer pumps are functionally tested every month during routine testing of the EDGs.
Therefore, based on all the above, the proposed changes wih not involve a significant reduction in a margin of safety.
Safety and Significant Hazards Consideration Determination Based on the above No Significant Hazards Consideration Determination, it is concluded that: (1) the proposed change does not constitute a significant hazards consideration as defined by 10CFR50.92; and (2) there is a reasonable assurance that the health and safety of the public will not be endangered by the proposed change; and (3) this action will not result in a condition which i
significantly alters the impact of the station on the environment as described in the NRC final environmental statement.
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ATTACHMENT A to W3F1-99-0019 EXISTING FSAR SECTION 9.5.4.1
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'WSES-FSAR-UNIT-3 b
9.5.4
- DlESEL GENERATOR FUEL OIL STORAGE AND TRANSFER SYSTEMS
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9.5.4.1 '
Desson Bases 1
' The Diesel Generator Fuel Oil Storage and Transfer System is designed to:.
' p) provide oil storage capacity in each storage tank for seven days operation of one diesel
- generator to meet the engineered safety feature load requirements following a loss of.
. offsite power and a design basis accident, b) maintain fuel supply to at least one diesel engine assuming a single active or passive failure, _.
c) withstand safe shutdown earthquake loads without loss of function, and d)
. withstand tomado wind loading and maximum flood levels without loss of function.
All safety related portions of the diesel engine fuel oil storage and transfer system, are designed to ANSI Standard N195 " Fuel Oil System for Standby Diesel Generator" and are seismic Category I and safety class 3. (refer to Table 3.2-1). ANSI N195 is met by taking credit for the cross-tie 1
between the Fuel Oil Storage Tanks. This cross-t'e is discussed in section 9.5.4.2, as shown in Figure 9.5-3.
The 10% fuel oil margin required by ANSI N195 is not available in each diesel generator fuel oil -
storage tank. Therefore, during Cycle 9. an equivalent margin has been established onsite by use
' of compensatory measures.
Protection of the Diesel Generator Fuel Oil Storage and Transfer System from wind and tomado
. effects is discussed in Sechon 3.3. Flood design is discussed in Section 3.4. Missile protection is discussed in Seebon 3.5. Protechon against dynamic effects associated with the postulated rupture of piping is discussed in Section 3.6. Environmental design is discussed in Sechon 3.11.
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Revision 9 (12/97)-
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l ATTACHMENT B to W3F1-99-0019 PROPOSED FSAR SECTION 9.5.4.1
WSES-FSAR-UNIT,
l 9.5.4 DIESEL GENERATOR FUEL OIL STORAGE AND TRANSFER SYSTEMS l
9.G.4.1 Desian Bases
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The Diesel Generator Fuel Oil Storage and Transfer System is designed to:
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l a) provide oil storage capacity in each storage tank for seven days operation of one diesel I
generator to meet the engineered safety feature load requirements foHowing a loss of offsite power and a design basis accident, j
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b) maintain fuel supply to at least one diesel engine assuming a single active or passive i
failure,-
c) withstand safe shutdown earthquake loads without loss of function, and d) withstand tomado wind loading and maximum flood levels without loss of function.
All safety related rtions of the d' el engine fuel oil stor e and transfer system, re designed to ANSI Stand d N195 " Fuel Oi ystem for Standby D' sel Generator" and are ismic Category I and safety ss 3. (refer to T le 3.2-1). ANSI N19 s met by taking credit f the cross-tie between t Fuel Oil Storage anks. This cross-tie i discussed in section 9.
.2, as shown in i
Figure 9. -3.,
The
% fuel oil margin uired by ANSI N195 not available in each d' sel generator fuel o' sto ge tank. Therefor, during Cycle 9, an e tvalent margin has bee stablished onsite use o
mpensatory me ures.
i Protection of the Diesel Generator Fuel Oil Storage and Transfer System from wind and tomado i
effects is discussed in Section 3.3. Flood design is discussed in Section 3.4, Missile protection is discussed in Section 3.5. Protection against dynamic effects associated with the postulated rupture of piping is discussed in Section 3.6. Environmental design is discussed in Section 3.11.
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Revision 9 (12/97)
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l INSERT A All safety related portions of the Waterford 3 diesel engine fuel oil storage and transfer system, are seismic Category 1, safety class 3, and designed to ANSI Standard N195-1976, " Fuel Oil Storage System for Standby Diesel Generator,"
with the exceptions as listed below:
- a).
The Waterford 3 Emergency Diesel Generator (EDG) Fuel Oil Storage
- Tanks (FOSTs) contain a seven-day fuel oil supply using the time dependent method for calculating stored fuel oil. The Waterford 3 EDG FOSTs do not contain an explicit allowance for margin.
l b).
The Waterford 3 EDG FOSTs do not contain an explicit allowance for fuel j
consumption required for periodic testing.
c),
The Waterford 3 EDG fuel oil feed tank suction is located on the bottom of the feed tank.
d)
The Waterford 3 EDG fuel oil feed tank overflow discharges to the sump pump system.
'e).
The Waterford 3 EDG fuel oil transfer system does not have a pressure l
indicator located at the discharge of the fuel oil transfer pumps.
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ATTACHMENT C to W3F1-99-0019 PROBABLISTIC SAFETY ASSESSMENT
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PROBABILISTIC SAFETY ASSESSMENT Waterford 3 has determined, using Probabilistic Safety Assessment (PSA) techniques, that
- increasing the fuel oil storage capacity from 7.1 days to 7.7 days (an additional 0.6 days) has
- no risk significance. The basis for this conclusion is as follows.
The frequency of a long-term loss of offsite power (seven days or longer) can be estimated from industry loss of offsite power experience. EPRI TR-106306, " Losses of Off-Site Power at U.S. Nuclear Power Plants-Through 1995," contains data from 1980 to 1995 on loss of offsite power (LOOP) events lasting longer than one hour. Of 26 such events, the longest was the 1992 Hurricane Andrew event at Turkey Point, at five days,12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />, and 30 minutes. The next longest event was only 25 hours2.893519e-4 days <br />0.00694 hours <br />4.133598e-5 weeks <br />9.5125e-6 months <br /> in duration.
Assuming that a seven day LOOP event has the same probability as this 5.5 day event gives one long-term LOOP event in the 16 year data period. Restricting the plant population that could be affected by a severe hurricane such as Andrew to plants on the Gulf coast and the Atlantic coast south of Cape Cod within 50 miles of the coast (the distance of Waterford 3 from the Gulf of Mexico) gives a total of 283 unit-years of operation for 22 plants. Dividing one long-4 term LOOP events by 283 unit-years gives a long-term LOOP frequency of 7.1x10 per year.
There are two major potential causes of failure to replenish the FOSTs during a long-term.
LOOP event such as happened at Turkey Point: 1) the operators failing to recognize that they need to replenish the tanks and 2) inability to get fuel to the plant due to such factors as loss of the communication systert debris on the roads, damage to oil company storage facilities, etc.
The probability of the oper@rs failing to recognize the need to replenish the FOSTs is very low.'.Even assuming they have only two hours to make the decision, instead of the days actually available, the probability of such a decisional failure is calculated using the Waterford 3 4
' PSA Human Reliability Model as 7.5x10. Combining this with the long-term LOOP frequency gives' a core damage frequency due to a long-term LOOP with failure of the operators to 4
recognize the need to replenish the FOSTs of 2.6x10 per year. Since this is of negligible risk significance, an additional 0.6 days (14.4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />) has no risk significance.
The probability that fuel cannot be delivered b Waterford 3 within seven days after a hurricane is harder to quantify, since there is so little exponenw and so marf possible means of accomplishing the job. Even with the catastrophic damage from hurricane Andrew at Turkey Point, the road to the plant was cleared in less than 38 hours4.398148e-4 days <br />0.0106 hours <br />6.283069e-5 weeks <br />1.4459e-5 months <br /> and fuel was delivered soon after.
Waterford 3 is located in a heavy industrial corridor of Louisiana where there are many oil refineries and oil storage facilities. Even if many facilities were damaged, there are many other sources of fuel available its the area. Waterford 3 is located on the Mississippi River at an elevation of about 19 feet above sea level (minimizing the flooding hazard). Even in the very unlikely event that no fuel was available locally, in seven days fuel could be shipped by barge via the Mississippi River from areas outside the damage zone.
Considering the time available. the many sources of fuel in the area, and the variety of means available for getting fuel to the site, it is very unlikely that the FOSTs would not be replenished within seven days. Adding an extra 14.4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> to a seven day available time to replenish the tanks has no significant effect on the core damage risk.
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