ML032520592

Technical Specification Bases (TSB) Change

ML032520592
Person / Time
Site:	Oconee
Issue date:	08/21/2003
From:	Rosalyn Jones Duke Power Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
Download: ML032520592 (16)

Text

^ Duke R.

A.

JONES rWPowere Vice President A Duke Energy Company Duke Power 29672 / Oconee Nuclear Site 7800 Rochester Highway Seneca, SC 29672 864 885 3158 864 885 3564 fax August 21, 2003 U. S. Nuclear Regulatory Commission Washington, D. C. 20555 Attention: Document Control Desk

Subject:

Oconee Nuclear Station Docket Numbers 50-269, 270, and 287 Technical Specification Bases (TSB) Change Please see attached revisions to Tech Spec Bases 3.5.3, Low Pressure Injection, which were implemented on August 6, 2003. contains the new TSB pages and Attachment 2 contains the markup version of the Bases pages.

If any additional information is needed, please contact Larry E. Nicholson, at (864-885-3292).

Ve y yours, R

ones, Vice President Oconee Nuclear Site www. duke-energy. com

U. S. Nuclear Regulatory Commission August 21, 2003 Page 2 cc:

Mr. L. N. Qishan Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, D. C. 20555 Mr. L. A. Reyes, Regional Administrator U. S. Nuclear Regulatory Commission -

Region II Atlanta Federal Center 61 Forsyth St., SW, Suite 23T85 Atlanta, Georgia 30303 Mel Shannon Senior Resident Inspector Oconee Nuclear Station Mr. Henry Porter Director Division of Radioactive Waste Management Bureau of Land and Waste Management Department of Health & Environmental Control 2600 Bull Street Columbia, SC 29201

LPI B 3.5.3 B 3.5 EMERGENCY CORE COOLING SYSTEMS (ECCS)

B 3.5.3 Low Pressure Injection (LPI)

BASES BACKGROUND The function of the ECCS is to provide core cooling to ensure that the reactor core is protected after any of the following accidents:

a.

Loss of coolant accident (LOCA);

b.

Rod ejection accident (REA);

c.

Steam generator tube rupture (SGTR); and

d.

Main steam line break (MSLB).

There are two phases of ECCS operation: injection and recirculation. In the injection phase, all injection Is initially added to the Reactor Coolant System (RCS) via the cold legs or Core Flood Tank (CFT) lines to the reactor vessel. After the borated water storage tank (BWST) has been depleted, the recirculation phase is entered as the suction is transferred to the reactor building sump.

Two redundant low pressure injection (LP) trains are provided. The LPI trains consist of piping, valves, instruments, controls, heat exchangers, and pumps, such that water from the borated water storage tank (BWST) can be injected into the Reactor Coolant System (RCS). In MODES 1, 2 and 3, both trains of LPI must be OPERABLE. This ensures that 100% of the core cooling requirements can be provided even In the event of a single active failure. Only one LPI train Is required for MODE 4. The LPI discharge header crossover valves must be manually (locally and remotely)

OPERABLE in MODE 1, 2, and 3 to assure abundant, long term core cooling. The Reactor Building Spray trains provide a support function for the OPERABILITY of the LPI discharge header crossover valves.

Alignment (via automatic, remote manual, or local manual means) of the Reactor Building Spray trains prior to cross connection of LPI headers prevents potential overpressurization of the LPI suction headers.

A suction header supplies water from the BWST or the reactor building sump to the LPI pumps. LPI discharges into each of the two core flood nozzles on the reactor vessel that discharge into the vessel downcomer area.

The LPI pumps are capable of discharging to the RCS at an RCS pressure of approximately 200 psia. When the BWST has been nearly emptied, the OCONEE UNITS 1, 2, & 3 B 3.5.3-1 BASES REVISION DATED 08/06/03

LPI B 3.5.3 BASES BACKGROUND suction for the LPI pumps is manually transferred to the reactor building (continued) sump.

In the long term cooling period, flow paths In the LPI System are established to preclude the possibility of boric acid in the core region reaching an unacceptably high concentration. Two gravity flow paths are available by means of a drain line from the hot leg to the Reactor Building sump which draws coolant from the top of the core, thereby inducing core circulation. The system is designed with redundant drain lines.

During a large break LOCA, RCS pressure will rapidly decrease. The LPI System is actuated upon receipt of an ESPS signal. If offsite power is available, the safeguard loads start immediately.

offsite power is not available, the Engineered Safeguards (ES) buses are connected to the Keowee Hydro Units. The time delay (38 seconds) associated with Keowee Hydro Unit startup and LPI pump starting determines the time required before pumped flow is available to the core following a LOCA. Full LPI flow is not available until the LPI header isolation valve strokes full open. The ES signal has been removed from LP-21 and LP-22. These valves shall be open when automatic initiation of the LPI system is required. If either one is closed during this time, the associated LPI and RBS train Is inoperable.

The LPI and HPI (LCO 3.5.2, High Pressure Injection (HPI)"), along with the passive CFTs and the BWST covered in LCO 3.5.1, Core Flood Tanks (CFTs),' and LCO 3.5.4, Borated Water Storage Tank (BWST),m provide the cooling water necessary to meet 10 CFR 50.46 (Ref. 1).

APPLICABLE The LCO helps to ensure that the following acceptance criteria for the SAFETY ANALYSES ECCS, established by 10 CFR 50.46 (Ref. 1), will be met following a LOCA:

a.

Maximum fuel element cladding temperature is

• 22000F;

b.

Maximum cladding oxidation is S 0.17 times the total cladding thickness before oxidation;

c.

Maximum hydrogen generation from a zirconium water reaction is S 0.01 times the hypothetical amount generated if all of the metal in the cladding cylinders surrounding the fuel, excluding the cladding surrounding the plenum volume, were to react;

d.

Core is maintained in a coolable geometry; and

e.

Adequate long term core cooling capability is maintained.

OCONEE UNITS 1, 2, & 3 B 3.5.3-2 BASES REVISION DATED 08106/03

LPI B 3.5.3 BASES APPLICABLE The LCO also helps ensure that reactor building temperature limits are SAFETY ANALYSES met.

(continued)

The LPI System is assumed to provide injection in the large break LOCA analysis at full power (Ref. 2). This analysis establishes a minimum required flow for the LPI pumps, as well as the minimum required response time for their actuation.

The large break LOCA event assumes a loss of offsite power and a single failure (loss of the CT-4 transformer). For analysis purposes, the loss of offsite power assumption may be conservatively inconsistent with the assumed operation of some equipment, such as reactor coolant pumps (Ref. 3). During the blowdown stage of a LOCA, the RCS depressurizes as primary coolant is ejected through the break into the reactor building. The nuclear reaction Is terminated by moderator voiding during large breaks.

Following depressurization, emergency cooling water is injected into the reactor vessel core flood nozzles, then flows into the downcomer, fills the tower plenum, and refloods the core.

In the event of a Core Flood line break which results in a LOCA, with a concurrent single failure on the unaffected LPI train opposite the Core Flood break, the LPI discharge header crossover valves (LP-9 and LP-1 0) must be capable of being manually (locally and remotely) opened. The LPI cooler outlet throttle valves and LPI header isolation valves must be capable of being manually opened to provide assurance that flow can be established in a timely manner even if the capability to operate them from the control room is lost. These manual actions will allow cross-connection of the LPI pump discharge to the intact LPVCore Flood tank header to provide abundant emergency core cooling.

The safety analyses show that an LPI train will deliver sufficient water to match decay heat bolloff rates for a large break LOCA.

In the large break LOCA analyses, full LPI is not credited until 74 seconds after actuation of the ESPS signal. This is based on a loss of offsite power and the associated time delays in Keowee Hydro Unit startup, valve opening and pump start. Further, LPI flow is not credited until RCS pressure drops below the pump's shutoff head. For a large break LOCA, HPI Is not credited at all.

The LPI trains satisfy Criterion 3 of 10 CFR 50.36 (Ref. 4).

LCO In MODES 1, 2, and 3, two independent (and redundant) LPI trains are required to ensure that at least one LPI train is available, assuming a single failure in the other train. Additionally, individual components within the LPI OCONEE UNITS 1, 2, & 3 B 3.5.3-3 BASES REVISION DATED 08/06103

LPI B 3.5.3 BASES LCO (continued) trains may be called upon to mitigate the consequences of other transients and accidents. Each LPI train includes the piping, instruments, pumps, valves, heat exchangers and controls to ensure an OPERABLE flow path capable of taking suction from the BWST upon an ES signal and the capability to manually (remotely) transfer suction to the reactor building sump. The safety grade flow indicator of an LPI train is required to support OPERABILITY of the LPI and RBS trains to preclude NPSH or runout pro-blems. For Unit 1, during an event, RBS train flow must be monitored and controlled to support the LPI pumps to ensure that the NPSH requirements for the LPI pumps are not exceeded. If the flow instrumentation or the capability to control the flow in a RBS train is unavailable then the associated LPI train's OPERABILITY is affected until such time as the RBS train is restored or the associated RBS pump is placed in a secured state to prevent actuation during an event. For Units 2 and 3, RBS flow is hydraulically maintained by system resistance, and throttling of RBS flow Is not required. Therefore, RBS flow indication is not required to support LPI or RBS train OPERABILITY. The safety grade flow indicator associated with LPSW flow to an LPI cooler is required to be OPERABLE to support LPI train OPERABILITY.

LPI BWST Suction Valves,'LP-21 and LP-22 do not have an ES signal to open. These valves shall be open when automatic initiation of the LPI and the RBS system is required to be OPERABLE. If either one Is closed during this time, the associated LPi and RBS train is inoperable.

In MODE 4, one of the two LPI trains is required to ensure sufficient LPI flow is available to the core.

During an event requiring LPI injection, a flow path is required to provide an abundant supply of water from the BWST to the RCS, via the LPI pumps and their respective supply headers, to the reactor vessel. In the long term, this flow path may be switched to take its supply from the reactor building sump.

This LCO Is modified by three Notes. Note 1 changes the LCO requirement when in MODE 4 for the number of OPERABLE trains from two to one. Note 2 allows an LPI train to be considered OPERABLE during alignment, when aligned or when operating for decay heat removal if capable of being manually (remotely) realigned to the LPI mode of operation. This provision is necessary because of the dual requirements of the components that comprise the LPI and decay heat removal modes of the LPI System. Note 3 requires the LPI discharge header crossover valves (LP-9 and LP-10) to be OPERABLE in MODES 1, 2, and 3.

The flow path for each train must maintain its designed Independence to ensure that no single failure can disable both LPI trains. If both LPI OCONEE UNITS 1, 2, & 3 B 3.5.3-4 BASES REVISION DATED 08106/03

LPI B 3.5.3 BASES LCO (continued) discharge header crossover valves (LP-9 and LP-10) are simultaneously open then only one LPI train is considered OPERABLE.

APPLICABILITY In MODES 1, 2 and 3, the LPI train OPERABILITY requirements for the Design Basis Accident, a large break LOCA, are based on full power operation. The LPI discharge crossover valve OPERABILITY requirements for CFT line break is based on full power operation. Although reduced power would not require the same level of performance, the accident analysis does not provide for reduced cooling requirements in the lower MODES.

In MODE 4, one OPERABLE LPI train is acceptable without single failure consideration on the basis of the stable reactivity condition of the reactor and the limited core cooling requirements.

In MODES 5 and 6, unit conditions are such that the probability of an event requiring LPI injection Is extremely low. Core cooling requirements in MODE 5 are addressed by LCO 3.4.7, RCS Loops-MODE 5, Loops Filled," and LCO 3.4.8, RCS Loops-MODE 5, Loops Not Filled." MODE 6 core cooling requirements are addressed by LCO 3.9.4, DHR and Coolant Circulation-High Water Level,' and LCO 3.9.5, DHR and Coolant Circulation-Low Water Level."

ACTIONS A.1 With one LPI train inoperable in MODES 1,2 or 3, the inoperable train must be returned to OPERABLE status within 7 days. The 7 day Completion Time is based on the findings of the deterministic and probabilistic analysis in Reference 7. Reference 7 concluded that extending the Completion Time to 7 days for an inoperable LPI train improves plant operational flexibility while simultaneously reducing overall plant risk. Specifically, the risk incurred by having the LPI train unavailable for a longer time at power will be substantially offset by the benefits associated with avoiding unnecessary plant transitions and by reducing risk during shutdown operations.

B.1 With one or more LPI discharge crossover valves inoperable, the inoperable valve(s) must be returned to OPERABLE status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.

The 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> Completion Time is based on NRC recommendations (Ref. 5) that are based on a risk evaluation and is a reasonable time for many repairs.

OCONEE UNITS 1, 2, & 3 B 3.5.3-5 BASES REVISION DATED 08/06/03

LPI B 3.5.3 BASES ACTIONS C.1 If the Required Action and associated Completion Time of Condition A or B are not met, the unit must be brought to a MODE in which the LCO does not apply. To achieve this status, the unit must be brought to at least MODE 3 within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and MODE 4 within 60 hours6.944444e-4 days <br />0.0167 hours <br />9.920635e-5 weeks <br />2.283e-5 months <br />. The allowed Completion Times are reasonable, based on operating experience, to reach the required unit conditions from full power conditions in an orderly manner and without challenging unit systems.

D.1 With one required LPI train Inoperable in MODE 4, the unit is not prepared to respond to an event requiring low pressure injection and may not be prepared to continue cooldown using the LPI pumps and LPI heat exchangers. The Completion Time of Immediately, which would initiate action to restore at least one LPI train to OPERABLE status, ensures that prompt action is taken to restore the required LPI capacity. Normally, in MODE 4, reactor decay heat must be removed by a decay heat removal (DHR) loop operating with suction from the RCS. If no LPI train is OPERABLE for this function, reactor decay heat must be removed by some aftemate method, such as use of the steam generator(s).

The alternate means of heat removal must continue until one of the inoperable LPI trains can be restored to operation so that continuation of decay heat removal (DHR) is provided.

With the LPI pumps (including the non ES pump) and LPI heat exchangers inoperable, it would be unwise to require the unit to go to MODE 5, where the only available heat removal system is the LPI trains operating in the DHR mode. Therefore, the appropriate action is to initiate measures to restore one LPI train and to continue the actions until the subsystem is restored to OPERABLE status.

D.2 Required Action D.2 requires that the unit be placed in MODE 5 within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. This Required Action is modified by a Note that states that the Required Action is only required to be performed if a DHR loop Is OPERABLE. This Required Action provides for those circumstances where the LPI trains may be inoperable but otherwise capable of providing the necessary decay heat removal. Under this circumstance, the prudent action is to remove the unit from the Applicability of the LCO and place the unit in a stable condition in MODE 5. The Completion Time of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> is reasonable, based on operating experience, to reach MODE 5 in an orderly manner and without challenging unit systems.

OCONEE UNITS 1, 2, & 3 B 3.5.3-6 BASES REVISION DATED 08/06103

LPI B 3.5.3 BASES SURVEILLANCE SR 3.5.3.1 REQUIREMENTS Verifying the correct alignment for manual and non-automatic power operated valves in the LPI flow paths provides assurance that the proper flow paths will exist for LPI operation. This SR does not apply to valves that are locked, sealed, or otherwise secured in position, since these valves were verified to be in the correct position prior to locking, sealing, or securing. Similarly, this SR does not apply to automatic valves since automatic valves actuate to their required position upon an accident signal.

This Surveillance does not require any testing or valve manipulation; rather, it involves verification that those valves capable of being mispositioned are in the correct position. The 31 day Frequency is appropriate because the valves are operated under administrative control, and an inoperable valve position would only affect a single train. This Frequency has been shown to be acceptable through operating experience.

When in MODE 4 an LPI train may be considered OPERABLE during alignment, when aligned or when operating for decay heat removal if capable of being manually realigned to the LPI mode of operation.

Therefore, for this condition, the SR verifies that LPI is capable of being manually realigned to the LPI mode of operation.

SR 3.5.3.2 With the exception of systems in operation, the LPI pumps are normally in a standby, non-operating mode. As such, the flow path piping has the potential to develop voids and pockets of entrained gases. Venting the LPI pump casings periodically reduces the potential that such voids and pockets of entrained gases can adversely affect operation of the LPI System. This will also minimize the potential for water hammer, pump cavitation, and pumping of noncondensible gas (e.g., air, nitrogen, or hydrogen) into the reactor vessel following an ESPS signal or during shutdown cooling. This Surveillance Is modified by a Note that indicates it is not applicable to operating LPI pump(s). The 31 day Frequency takes into consideration the gradual nature of gas accumulation in the LPI piping and the existence of procedural controls governing system operation.

SR 3.5.3.3 Periodic surveillance testing of LPI pumps to detect gross degradation caused by impeller structural damage or other hydraulic component problems is required by Section Xi of the ASME Code (Ref. 6). SRs are specified in the Inservice Testing Program, which encompasses Section Xl of the ASME Code.

OCONEE UNITS 1, 2, & 3 B 3.5.3-7 BASES REVISION DATED 08/06/03

LPI B 3.5.3 BASES SURVEILLANCE REQUIREMENTS (continued)

SR 3.5.3.4 and SR 3.5.3.5 These SRs demonstrate that each automatic LPI valve actuates to the required position on an actual or simulated ESPS signal and that each LPI pump starts on receipt of an actual or simulated ESPS signal. This SR is not required for valves that are locked, sealed, or otherwise secured in position under administrative controls. The test will be considered satisfactory if control board indication verifies that all components have responded to the ESPS actuation signal properly (all appropriate ESPS actuated pump breakers have opened or closed and all ESPS actuated valves have completed their travel). The 18 month Frequency is based on the need to perform this Surveillance under the conditions that apply during a unit outage and the potential for an unplanned transient if the Surveillance were performed with the reactor at power. The 18 month Frequency is also acceptable based on consideration of the design reliability (and confirming operating experience) of the equipment. The actuation logic is tested as part of the ESPS testing, and equipment performance is monitored as par of the Inservice Testing Program.

SR 3.5.3.6 Periodic inspections of the reactor building sump suction inlet ensure that it is unrestricted and stays in proper operating condition. The 18 month Frequency is based on the need to perform this Surveillance under the conditions that apply during a unit outage, on the need to preserve access to the location, and on the potential for an unplanned transient if the Surveillance were performed with the reactor at power. This Frequency has been found to be sufficient to detect abnormal degradation and has been confirmed by operating experience.

SR 3.5.3.7 The function of the LPI discharge header crossover valves (LP-9, LP-10) is to open and allow a cross-connection between LPI trains. The LPI cooler outlet throttle valves (LP-12, LP-14) and LPI header isolation valves (LP-1 7, LP-1 8) must be capable of being manually opened to provide assurance that flow can be established in a timely manner even if the capability to operate them from the control room is lost. Manually cycling each valve open demonstrates the ability to fulfill this function. This test is performed on an 18 month Frequency. Operating experience has shown that these components usually pass the Surveillance when performed at the this Frequency. Therefore, the Frequency is acceptable from a reliability standpoint.

OCONEE UNITS 1, 2, & 3 B 3.5.3-8 BASES REVISION DATED 08106/03 I

LPI B 3.5.3 BASES (continued)

REFERENCES

1.

10 CFR 50.46.

2.

UFSAR, Section 15.14.3.3.6.

3.

UFSAR, Section 15.14.3.3.5.

4.

10 CFR 50.36.

5.

NRC Memorandum to V. Stello, Jr., from R.L. Baer, Recommended Interim Revisions to LCOs for ECCS Components," December 1, 1975.

6.

ASME, Boiler and Pressure Vessel Code, Section Xi, Inservice Inspection, Article IWV-3400.

7.

NRC Safety Evaluation of Babcok & Wilcox Owners Group (B&WOG) Topical Report BAW-2295, Revision 1, Justification for the Extension of Allowed Outage Time for Low Pressure Injection and Reactor Building Spray systems," (TAC No. MA3807) dated June 30, 1999.

OCONEE UNITS 1, 2, & 3 B 3.5.3-9 BASES REVISION DATED 0806/03

LPl B 3.5.3 B 3.5 EMERGENCY CORE COOLING SYSTEMS (ECCS)

B 3.5.3 Low Pressure Injection (LPI)

BASES BACKGROUND The function of the ECCS is to provide core cooling to ensure that the reactor core Is protected after any of the following accidents:

a.

Loss of coolant accident (LOCA);

b.

Rod ejection accident (REA);

c.

Steam generator tube rupture (SGTR); and

d.

Main steam line break (MSLB).

There are two phases of ECCS operation: injection and recirculation. In the injection phase, all injection is initially added to the Reactor Coolant System.(RCS) via the cold legs or Core Flood Tank (CFT) lines to the reactor vessel. After the borated water storage tank (BWST) has been depleted, the recirculation phase is entered as the suction Is transferred to the reactor building sump.

Two redundant low pressure injection (LPI) trains are provided. The LPI trains consist of piping, valves, instruments, controls, heat exchangers, and pumps, such that water from the borated water storage tank (BWST) can be injected into the Reactor Coolant System (RCS). In MODES 1, 2 and 3, both trains of LPI must be OPERABLE. This ensures that 100% of the core cooling requirements can be provided even in the event of a single active failure. Only one LPI train is required for MODE 4. The LPI discharge header crossover valves must be manually (locally and remotely)

OPERABLE in MODE 1, 2, and 3 to assure abundant, long term core cooling. The Reactor Building Spray trains provide a support function for the OPERABILITY of the LPI discharge header crossover valves.

Alignment (via automatic, remote manual, or local manual means) of the Reactor Building Spray trains prior to cross connection of LPI headers prevents potential overpressurization of the LPI suction headers.

A suction header supplies water from the BWST or the reactor building sump to the LPI pumps. LPI discharges into each of the two core flood nozzles on the reactor vessel that discharge into the vessel downcomer area.

OCONEE UNITS 1, 2, & 3 B 3.5.3-1 BASES REVISION DATED 04/16/03

LPI B 3.5.3 BASES B

KG UNg The LPI pumps are capable of discharging to the RCS at an RCS continued) ressure of approximately 200 psia. When the BWST has been nearly

/ ~

w Qmptied, the suction for the LPI pumps is manually transferred to the eactor building sump.

In he long term cooling period, flow paths In the LPI System are e

e ablished to preclude the possibility of boric acid in the core region i 1 g

4 ok r

ching an unacceptably high concentration. Two gravity flow paths are I <

V vaiable by means of a drain line from the hot leg to the Reactor Building v)

A mp which draws coolant from the top of the core, thereby inducing core culation. The system Is designed with redundant drain lines.

-Q R >; at >

ering a large break LOCA, RCS pressure will rapidly decrease. The LPI m Is actuated upon receipt of an ESPS signal. If offsite power Is

\\ <

3 vw *-

vailable, the safeguard loads start immediately. If offsite power is not Y

Q

>%<ailable, the Engineered Safeguards (ES) buses are connected to the k eowee Hydro Units. The time delay (38 seconds) associated with

.*?

_-~

e j

owee Hydro Unit startup ancdfmp starting determines the time required v:) NJ 3 t o efore pumped flow is available to the core following a LOCA. Full LPI flow v:

rt)

,3not available~until the IPlvalve strokes full open.

(e e IPI and HPI (LCO 3.5.2, "High Pressure njection (HPI)O), along with s he passive CFTs and the BWST covered In LCO 3.5.1, Core Flood Tanks

\\~ Z;.Q ; (CFTs),' and LCO 3.5A, 0Borated Water Storage Tank (BWST),0 provide the cooling water necessary to meet 10 CFR 50.46 (Ref. 1).

APPLICABLE The LCO helps to ensure that the following acceptance criteria for the SAFETY ANALYSES ECS, established by 10 CFR 50.46 (Ref. 1), will be met following a LOCA:

a.

Maximum fuel element cladding temperature is

• 22000F;

b.

Maximum cladding oxidation is

• 0.17 times the total cladding thickness before oxidation;

c.

Maximum hydrogen generation from a zirconium water reaction is

• 0.01 times the hypothetical amount generated if all of the metal in the cladding cylinders surrounding the fuel, excluding the cladding surrounding the plenum volume, were to react;

d.

Core is maintained in a coolable geometry; and

e.

Adequate long term core cooling capability is maintained.

The LCO also helps ensure that reactor building temperature limits are met.

OCONEE UNITS 1, 2, & 3 B 3.5.3-2 BASES REVISION DATED 04/16/03

LPI B 3.5.3 BASES LCO and accidents. Each LPI train Includes the piping, instruments, pumps, (continued) valves, heat exchangers and controls to ensure an OPERABLE flow path capable of taking suction from the BWST upon an ES signal and the d

vy capability to manually (remotely) transfer suction to the reactor building

'1.d

\\tsump. The safety grade flow indicator of an LPI train is required to support ts..d) - f ad A\\ OPERABILITY of the LPi and RBS trains to preclude NPSH or runout pro-blems. In addition, durng an event, RBS train flow must be monitored and

( (>Glj S

controlled to support the LPI pumps to ensure that the NPSH requirements t

I t W t

z tfor the LPI pumps are not exceeded. If the flow instrumentation or the 0

capability to control the flow In a RBS train is unavailable then the ssociated LPI train's OPERABILITY Is affected until such time as the RBS I

d n

rain is restored or the associated RBS pump is placed in a secured state to

>E Ic p t i >Qrevent actuation during an event. The safety grade flow indicator

? 2

°J s u >

ssociated with LPSW flow to an LPI cooler Is required to be OPERABLE support LPI train OPERABILITY.

c _

O E

n MODE 4, one of the two LPI trains is required to ensure sufficient LPI w Is available to the core.

,(

I ring an event requiring LPI Injection, a flow path is required to provide an S d Z

a v

zundant supply of waterfrom the'BWST to the RCS, via the LPI pumps QJ a)-'<-8 t~sE e d their respective supply headers, to the reactor vessel. In the long term, of t

flow path may be switched to take its supply from the reactor building

2) >^o

> a!.T Is LCO is modified by three Notes. Note 1 changes the LCO 8 l rq uirement when in MODE 4 for the number of OPERABLE trains from to one. Note 2 allows an LPI train to be considered OPERABLE during

-A agnment, when aligned or when operating for decay heat removal if able of being manually (remotely) realigned to the LPI mode of peration. This provision Is necessary because of the dual requirements of the components that comprise the LPI and decay heat removal modes of LIthe L System. Note 3 requires the LPI discharge header crossover valves (LP-9 and LP-1 0) to be OPERABLE in MODES 1, 2, and 3.

The flow path for each train must maintain its designed independence to ensure that no single failure can disable both LPI trains. If both LPI discharge header crossover valves (LP-9 and LP-10) are simultaneously open then only one LPI train Is considered OPERABLE.

APPLICABILITY In MODES 1, 2 and 3, the LPI train OPERABILITY requirements for the Design Basis Accident, a large break LOCA, are based on full power operation. The LPI discharge crossover valve OPERABILITY requirements for CFT line break is based on full power operation. Although reduced power would not require the same level of performance, the accident OCONEE UNITS 1, 2, & 3 B 3.5.3 BASES REVISION DATED 04/16/03