ML081260440

Technical Specification Bases (Tsb), Attachments 1 and 2

ML081260440
Person / Time
Site:	Oconee
Issue date:	04/29/2008
From:	Baxter D Duke Energy Carolinas
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
Download: ML081260440 (33)

Text

,=Jr Duke Energy DAVE BAXTER Vice President Oconee Nuclear Station Duke Energy Corporation ON01 VP17800 Rochester Highway Seneca, SC 29672 April 29, 2008 864-885-4460 864-885-4208 fax dabaxter@dukeenergy.com U. S. Nuclear Regulatory Commission Washington, D. C. 20555 Attention: Document Control Desk

Subject:

Duke Energy Carolinas, LLC Oconee Nuclear Station Docket Numbers 50-269, 270, and 287 Technical Specification Bases (TSB) Change On April 2, 2008 Station Management approved revisions to TSB 3.5.2, High Pressure Injection (HPI) to require the opening of the Low Pressure Injection (LPI)-HPI flow path discharge valves (LP-15 and LP-16) from the control room. Accessibility to the valves is limited during'an accident situation due to dose considerations.

Station Management also approved revision to TSB 3.7.16, Control Room Area Cooling Systems (CRACS), to eliminate reference to Updated Final Safety Analysis Report (UFSAR) chapter 3.11.5. This section of the UFSAR no longer addresses the Control Room Ventilation System and Chilled Water System.

Attachment 1 contains the new TSB pages, Attachment 2 contains the marked up version of the TSB pages.

If any additional information is needed, please contact Reene Gambrell at 864-885-3364.

Very truly yours, Dave Bax er Oconee Nuclear Site www. duke-energy, corn

U. S. Nuclear Regulatory Commission April 29, 2008 Page 2 cc: Mr. L. N. Olshan Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, D. C. 20555 Mr. Victor M. McCree Regional Administrator (Acting)

U. S. Nuclear Regulatory Commission - Region II Atlanta Federal Center 61 Forsyth St., SW, Suite 23T85 Atlanta, Georgia !30303 Andy Hutto Senior Resident Inspector Oconee Nuclear Station S. E. Jenkins, Section Manager Division of Waste Management S.C. Department of Health and Environmental Control 2600 Bull Street Columbia, SC 29201

U. S. Nuclear Regulatory Commission April 29, 2008 Page 3 bcc: w/o attachments L. F. Vaughn Ken Ashe - MNS R. D. Hart - CNS w/attachments Document Management ELL NSRB MR Coordinator (Ron Harris)

Licensing Working Group

HPI B 3.5.2 B 3.5 EMERGENCY CORE COOLING SYSTEMS (ECCS)

B 3.5.2 High Pressure Injection (HPI)

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) ',ia 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.

The HPI System consists of two independent trains, each of which splits to discharge into two RCS cold legs, so that there are a total of four HPI injection lines. Each train takes suction from the BWST, and has an automatic sucti6n valve and discharge valve which open upon receipt of an Engineered Safeguards Protective System (ESPS) signal. The two HPI trains are designed and aligned such that they are not both susceptible to any single active failure including the failure of any power operating component to operate or any single failure of electrical equipment. The HPI System is, not required to withstand passive failures.

There are three, ESPS actuated HPI pumps; the discharge flow paths for two of the pumps are normally aligned to automatically support HPI train "A" and the discharge flow path for the third pump is normally aligned to automatically support HPI train "B." The discharge flow paths can be manually aligned such that each of the HPI pumps can provide flow to either train. At least one pump is normally running to provide RCS makeup and seal injection to the reactor coolant pumps. Suction header cross-connect valves are normally open; cross-connecting the HPI suction OCONEE UNITS 1, 2, & 3 B 3.5.2-1 BASES REVISION DATED 04/11/08

HPI B 3.5.2 BASES BACKGROUND headers during normal operation was approved by the NRC in (continued) Reference 6. The discharge crossover valves (HP-409 and HP-410) are normally closed; these valves can be used to bypass the normal discharge valves and assure the ability to feed either train's injection lines via HPI pump "B." For each discharge valve and discharge crossover valve, a safety grade flow indicator is provided to enable the operator to throttle flow during an accident to assure that runout limits are not exceeded.

A suction header supplies water from the BWST or the reactor building sump (via the LPI-HPI flow path) to the HPI pumps. HPI discharges into each of the four RCS cold legs between the reactor coolant pump and.the reactor vessel. There is one flow limiting orifice in each of the four injection headers that connect to the RCS cold legs. If a pipe break were to occur in an HPI line between the last check valve and the RCS, the orifice in the broken line would limit the HPI flow lost through the break and maximize the flow supplied to the reactor vessel via the other line supplied by the HPI header.

The HPI pumps are capable of discharging to the RCS at an RCS pressure above the opening setpoint of the pressurizer safety valves. The HPI pumps cannot take suction directly from the sump. If the BWST is emptied and HPI is still needed, a cross-connect from the discharge side of the LPI pump to the suction of the HPI pumps would be opened. This is known as "piggy backing" HPI to LPI and enables continued HPI to the RCS.

The HPI System also functions to supply borated water to the reactor core following increased heat removal events, such as MSLBs.

The HPI and LPI (LCO 3.5.3, "Low Pressure Injection (LPI)") components, 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)," 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 < 22000 F;

b. Maximum cladding oxidation is *0.17 times the total cladding thickness before oxidation; OCONEE UNITS 1, 2, & 3 B 3.5.2-2 BASES REVISION DATED 04/11/08 I

HPI B 3.5.2 BASES APPLICABLE c. Maximum hydrogen generation from a zirconium water reaction is SAFETY ANALYSES < 0.01 times the hypothetical amount generated if all of the metal in (continued) 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 cooling capability is maintained.

The HPI System is credited in the small break LOCA analysis (Ref. 2).

This analysis establishes the minimum required flow and discharge head requirements at the design point for the HPI pumps, as well as the minimum required response time for their actuation. The SGTR and MSLB analyses also credit the HPI pumps, but these events are bounded by the small break LOCA analyses with respect to the performance requirements for the HPI System. The HPI System is not credited for mitigation of a large break LOCA.

During a small break LOCA, the HPI System supplies makeup water to the reactor vessel via the RCS cold legs. The HPI System is actuated upon receipt of an ESPS signal. If offsite power is available, the safeguard loads start immediately. If offsite power is not available, the Engineered Safeguards (ES) buses are connected to the Keowee Hydro Units. The time delay associated with Keowee Hydro Unit startup, HPI valve opening, and pump starting determines the time required before pumped flow is available to the core following a LOCA.

One HPI train provides sufficient flow to mitigate most small break LOCAs.

However, for cold leg breaks located on the discharge of the reactor coolant pumps, some HPI injection will be lost out the break; for this case, two HPI trains are required. Thus, three HPI pumps must be OPERABLE to ensure adequate cooling in response to the design basis RCP discharge small break LOCA. Additionally, in the event one HPI train fails to automatically actuate due to a single failure (e.g., failure of HPI pump "C" or HP-26), operator actions from the Control Room are required to cross-connect the HPI discharge headers within 10 minutes in order to provide HPI flow through a second HPI train (Ref. 6).

Hydraulic separation of the HPI discharge headers is required during normal operation to maintain defense-in-depth (i.e., independence of the HPI discharge headers). Additionally, hydraulic separation of the HPI discharge headers ensures that a complete loss of HPI would not occur in the event an accident were to occur with only two of the three HPI pumps OCONEE UNITS 1, 2, & 3 B 3.5.2-3 BASES REVISION DATED 04/11/08 1

HPI B 3.5.2 BASES APPLICABLE OPERABLE coincident with the HPI discharge headers cross-connected.

SAFETY ANALYSES A single active failure of an HPI pump would leave only one HPI pump to (continued) mitigate the accident. The remaining HPI pump could experience runout conditions and could fail prior to operator action to throttle flow or start another pump.

Hydraulic separation on the suction side of the HPI pumps could cause a loss of redundancy. With any one of the normally open suction header cross-connect valves closed, a failure of an automatic suction valve to open during an accident could cause two pumps to lose suction. Thus, the suction header cross-connect valves must remain open.

The safety analyses show that the HPI pump(s) will deliver sufficient water for a small break LOCA and provide sufficient boron to maintain the core subcritical.

The HPI System satisfies Criterion 3 of 10 CFR 50.36 (Ref. 3).

LCO In MODES 1 and 2, and MODE 3 with RCS temperature > 350 0 F, the HPI System is required to be OPERABLE with:

a. Two HPI trains OPERABLE;

b. An additional HPI pump OPERABLE;

c. Two LPI-HPI flow paths OPERABLE;

d. Two HPI discharge crossover valves OPERABLE;

e. HPI suction headers cross-connected; and

f. HPI discharge headers separated.

The LCO establishes the minimum conditions required to ensure that the HPI System delivers sufficient water to mitigate a small break LOCA.

Additionally, individual components within the HPI trains may be called upon to mitigate the consequences of other transients and accidents.

Each HPI train includes the piping, instruments, pump, valves, and controls to ensure an OPERABLE flow path capable of taking suction from the BWST and injecting into the RCS cold legs upon an ESPS signal. For an HPI train to be OPERABLE, the associated HPI pump must be capable of OCONEE UNITS 1, 2, & 3 B 3.5.2-4 BASES REVISION DATED 04/11/08 I

HPI B 3.5.2 BASES LCO taking suction from the BWST through the suction header valve associated (continued) with that train upon an ESPS signal. For example:

1) if HPI pump "B" is being credited as part of HPI train "A," then it must be capable of taking suction through HP-24 upon an ESPS signal; or

2) if HPI pump "B" is being credited as part of HPI train "B," then it must be capable of taking suction through HP-25 upon an ESPS signal.

The safety grade flow indicator associated with the normal discharge valve is required to be OPERABLE to support the associated HPI train's automatic OPERABILITY.

To support HPI pump OPERABILITY, the piping, valves and controls which ensure the HPI pump can take suction from the BWST upon an ESPS signal are required to be OPERABLE.

To support HPI discharge crossover valve OPERABILITY, the safety grade flow indicator associated with the HPI discharge crossover valve is required to be OPERABLE.

To support LPI-HPI flow path OPERABILITY, each flow path must be capable of being supplied by an OPERABLE LPI train. When capable of being supplied by an OPERABLE LPI train:

1) An LPI-HPI flow path, including the piping, instruments, valves and controls, must be in-place to ensure the capability to transfer suction to the reactor building sump from the control room. Within the LPI-HPI flow path are the LPI discharge valves to the LPI-HPI flow path (LP-15 and LP-16).

2) The LPI discharge valves to the LPI-HPI flow path must be capable of being opened from the control room for the LPI-HPI flow path to be OPERABLE.

The OPERABILITY requirements regarding the LPI System are addressed in LCO 3.5.3, "Low Pressure Injection (LPI)."

As part of the LPI-HPI flow path, the piping, instruments, valves and controls upstream of LP-1 5 and LP-1 6 are part of the LPI system and are subject to LCO 3.5.3 (Low Pressure Injection system) requirements. The piping, instruments, valves and controls downstream of and including LP-15 and LP-1 6, are part of the HPI system and are subject to LCO 3.5.2 (High Pressure Injection system) requirements.

OCONEE UNITS 1, 2, & 3 B 3.5.2-5 BASES REVISION DATED 04/11/08 1

HPI B 3.5.2 BASES LCO When a LPI-HPI flow path is inoperable due to the flow path's associated (continued) LPI train being inoperable for maintenance only, the piggyback line and associated components may also be inoperable for greater than 72-hours up to the associated LPI train's maximum allowed outage time of 7-days.

For this scenario, any valve along the piggyback line flowpath can be used as an isolation boundary, with power removed as necessary, but no physical work is allowed to be performed on any component along the piggyback line flowpath without entering the applicable TS LCO condition.

This is allowed because with an associated LPI train inoperable, there is no water source for the LPI-HPI piggyback function. This support (LPI train) and supported (LPI-HPI piggyback) relationship is subject to the requirements of TS LCO 3.0.6.

During an event requiring HPI actuation, a flow path is provided to ensure an abundant supply of water from the BWST to the RCS via the HPI pumps and their respective discharge flow paths to each of the four cold leg injection nozzles and the reactor vessel. In the recirculation phase, this flow path is transferred from the control room to take its supply from the reactor building sump and to supply borated water to the RCS via the LPI-HPI flow path (piggy-back mode).

The OPERABILITY of the HPI System must be maintained to ensure that no single active failure can disable both HPI trains. Additionally, while the HPI System was not designed to cope with passive failures, the HPI trains must be maintained independent to the extent possible during normal operation. The NRC approved exception to this principle is cross-connecting the HPI suction headers during normal operation (Ref. 6).

APPLICABILITY In MODES 1 and 2, and MODE 3 with RCS temperature > 3500 F, the HPI System OPERABILITY requirements for the small break LOCA are based on analysis performed at 100% RTP. The HPI pump performance is based on the small break LOCA, which establishes the pump performance curve.

Mode 2 and MODE 3 with RCS temperature > 350°F requirements are bounded by the MODE 1 analysis.

In MODE 3 with RCS temperature < 350°F and in MODE 4, the probability of an event requiring HPI actuation is significantly lessened. In this operating condition, the low probability of an event requiring HPI actuation and the LCO 3.5.3 requirements for the LPI System provide reasonable assurance that the safety injection function is preserved.

In MODES 5 and 6, unit conditions are such that the probability of an event requiring HPI injection is extremely low. Core cooling requirements in MODE 5 are addressed by LCO 3.4.7, "RCS Loops - MODE 5, Loops OCONEE UNITS 1, 2, & 3 B 3.5.2-6 BASES REVISION DATED 04/11/08

HPI B 3.5.2 BASES APPLICABILITY Filled," and LCO 3.4.8, "RCS Loops - MODE 5, Loops Not Filled."

(continued) MODE 6 core cooling requirements are addressed by LCO 3.9.4, "Decay Heat Removal (DHR) and Coolant Circulation - High Water Level," and LCO 3.9.5, "Decay Heat Removal (DHR) and Coolant Circulation - Low Water Level."

ACTIONS A.1 and A.2 With one HPI pump inoperable, or one or more HPI discharge crossover valve(s) (i.e., HP-409 and HP-410) inoperable, the HPI pump and discharge crossover valve(s) must be restored 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 HPI System continues to be capable of mitigating an accident, barring a single failure. 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. 4) that are based on a risk evaluation and is a reasonable time for many repairs.

In the event HP.I pump "C" becomes inoperable, Condition C mustbe entered as well as Condition A. Until actions are taken to align an HPI pump to HPI train "B," HPI train "B" is inoperable due to the inability to automatically provide injection in response to an ESPS signal.

This Condition permits multiple components of the HPI System to be inoperable concurrently. When this occurs, other Conditions may also apply. For example, if HPI pump "C" and HP-409 are inoperable coincidentally, HPI train "B" is incapable of being automatically actuated or manually aligned from the Control Room. Thus, Required Action C.1 would apply.

In order to utilize another HPI pump to supply HPI train "B" when HPI pump "C" is inoperable, HP-1 16 must be opened. This action results in cross-connecting the HPI discharge headers; thus, Condition E must be entered.

HP-1 15 may be closed to provide hydraulic separation provided that pump minimum flow requirements are maintained. However, two operating pumps would be required for this configuration, one to provide makeup flow and one to provide seal injection flow.

B.1, B.2, B.3, and B.4 If the Required Action and associated Completion Time of Condition A is not met, THERMAL POWER of the unit must be reduced to < 75% RTP within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. The 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> CompletionTime is reasonable, based on operating experience, to reach the required unit condition from full power conditions in an orderly manner and without challenging unit systems. This time is less restrictive than the Completion Time for Required Action C.1, OCONEE UNITS 1, 2, & 3 B 3.5.2-7 BASES REVISION DATED 04/11/08 1

HPI B 3.5.2 BASES ACTIONS B.1, B.2, B.3, and B.4 (continued) because the HPI System remains capable of performing its function, barring a single failure.

Two HPI trains are required to mitigate specific small break LOCAs, if no credit for enhanced steam generator cooling is assumed in the accident analysis. However, if equipment not qualified as QA-1 (i.e., an atmospheric dump valve (ADV) flow path for a steam generator) is credited for enhanced steam generator cooling, the safety analyses have determined that the capacity of one HPI train is sufficient to mitigate a small break LOCA on the discharge of the reactor coolant pumps if reactor power is

• 75% RTP.

Required Actions B.2, B.3, and B.4 modify the HPI pump and discharge crossover valve OPERABILITY requirements to permit reduced requirements at power levels < 75% RTP for an extended period of time.

Required Action B.2 provides a compensatory measure to verify by administrative means that the ADV flow path for each steam generator is OPERABLE within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. This compensatory measure provides additional assurance regarding the ability of the plant to mitigate an accident. Compliance with this requirement can be established by ensuring that the ADV flow path for each steam generator is OPERABLE in accordance with LCO 3.7.4, "Atmospheric Dump Valve (ADV) Flow Paths."

Required Actions B.3 and B.4 require that the HPI pump and discharge crossover valve(s) be restored to OPERABLE status within 30 days from initial entry into 'Condition A. The 30-day time period limits the time that the plant can operate while relying on non QA-1 ADVs to provide enhanced steam generator cooling to mitigate small break LOCAs. The 30-day time period is acceptable, because:

1. Without-crediting an ADV flow path, the HPI System remains capable of performing the safety function, barring a single failure;

2. If credit is taken for an ADV flow path for a steam generator, the safety analysis has demonstrated that only one HPI train is required to mitigate the consequences of a small break LOCA when THERMAL POWER is

• 75% RTP. Thus, for this case, the HPI System would be capable of performing its safety function even with an additional single failure; OCONEE UNITS 1, 2, & 3 B 3.5.2-8 BASES REVISION DATED 04/11/08 1

HPI B 3.5.2 BASES ACTIONS B.1, B.2, B.3, and B.4 (continued)

3. OPERABILITY of the ADV flow path for each steam generator is required to be confirmed by Required Action B.2 within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.

Additional defense-in-depth is provided, because the ADV flow path for only one steamrgenerator is required to mitigate the small break LOCA; and

4. A risk-informed assessment (Ref. 7) concluded that operating the plant in accordance with these Required Actions is acceptable.

ACTIONS C.1, C.2, and C.3 If the plant is operating with THERMAL POWER > 75% RTP, two HPI pumps capable of providing flow through two HPI trains are required. One HPI train is required to provide flow automatically upon receipt of an ESPS signal, while flow through the other HPI train must be capable of being established from the Control Room within 10 minutes. Thus, if the plantý is operating at > 75% RTP, and one HPI train is inoperable and incapable of being automatically actuated or manually aligned from the Control Room to provide flow post-accident, the HPI System would be incapable of performing its safety function. For this Condition, Required Action C.1 requires the power to be reduced to < 75% RTP within 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />. Required Action C.1 is modified by a Note which limits its applicability to the condition defined above. The 3 hour3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> Completion Time is considered reasonable to reduce the unit from full power conditions to < 75% RTP in an orderly manner and without challenging unit systems. The time frame is more restrictive than the Completion Time provided in Required Action B.1 for the same action, because the condition involves a loss of safety function.

If the plant is operating with THERMAL POWER > 75% RTP and the inoperable HPI train can be automatically actuated or manually aligned to provide flow post-accident, Required Action C.3 permits 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to restore the HPI train to an OPERABLE status.

If enhanced steam generator cooling is not credited in the accident analysis, two HPI trains are required to mitigate specific small break LOCAs with THERMAL POWER < 75% RTP. However, if equipment not qualified as QA-1 (i.e., an ADV flow path for a steam generator) is credited for enhanced steam generator cooling, the safety analyses have determined that the capacity of one HPI train is sufficient to mitigate a small break LOCA on the discharge of the reactor coolant pumps if THERMAL POWER is *- 75% RTP. In order to permit an HPI train to be inoperable regardless of the reason when THERMAL POWER is < 75% RTP, Required Action C.2 provides a compensatory measure to verify by administrative means that the ADV flow path for each steam generator is OCONEE UNITS 1, 2, & 3 B 3.5.2-9 BASES REVISION DATED 04/11/08

HPI B 3.5.2 BASES ACTIONS C.1, C.2, and C.3 (continued)

OPERABLE within 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />. This Required Action is modified by a Note which states that it is only required if THERMAL POWER is < 75% RTP.

This compensatory measure provides assurance regarding the ability of the plant to mitigate an accident while in the Condition and THERMAL POWER

_*75% RTP. Compliance with this requirement can be established by ensuring that the ADV flow path for each steam generator is OPERABLE in accordance with LCO 3.7.4, "Atmospheric Dump Valve (ADV) Flow Paths."

With one HPI train inoperable, the inoperable HPI train must be restored to OPERABLE status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. This action is appropriate because:

1. With THERMAL POWER < 75% RTP, the safety analysis demonstrates that only one HPI train is required to mitigate the consequences of a small break LOCA assuming credit is taken for the ADV flow path for one steam generator. The OPERABILITY of the ADV flow path for each steam generator is confirmed by Required Action C.2 within 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />. This provides additional defense-in-depth. Additionally, a risk-informed assessment (Ref. 7) concluded that operating the plant in accordance with this Required Actionis acceptable.

2. With THERMAL POWER > 75% RTP, the remaining OPERABLE HPI train is capable of automatic actuation, and the inoperable train can be manually aligned by operator action to cross-connect the.

discharge headers of the HPI trains. This manual action was approved by the NRC in Reference 6.

D.1 With the HPI suction headers not cross-connected, the HPI suction headers must be cross-connected within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. The HPI System continues to be capable of mitigating an accident, barring a single failure.

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. 4) that are based on a risk evaluation and is a reasonable time for many repairs.

An argument similar to that utilized for Required Actions B.2, B.3, and B.4 could have been made for operating the HPI System with the suction headers not cross-connected for an extended period of time. However, this action was not 6onsidered prudent, due to the potential of damaging two HPI pumps in the event HP-24 or HP-25 failed to open in response to an ESPS signal while the HPI suction headers were not cross-connected.

OCONEE UNITS 1, 2, & 3 B 3.5.2-10 BASES REVISION DATED 04/11/08 I

HPI B 3.5.2 BASES ACTIONS E.1 With the HPI discharge headers cross-connected, the independence of the HPI trains is not being maintained to the extent practical (i.e., defense-in-depth principle is not met). Thus, the HPI discharge headers must be hydraulically separated within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. This action limits the time period that the HPI discharge headers may be cross-connected. The 72-hour allowed outage time is acceptable, because cross-connecting the HPI discharge headers in conjunction with:

1. the rest'of the HPI System being OPERABLE would not result in the inability of the HPI System to perform its safety function even assuming a single active failure; and

2. an HPI pump being inoperable would not result in the inability of the HPI System to perform its safety function, barring a single failure.

However, in this condition, a single active failure of one of the two remaining OPERABLE HPI pumps could result in the remaining HPI pump failing due to runout.

F.1 With one LPI-HPI flow path inoperable, the inoperable LPI-HPI flow path must be restored 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 HPI System continues to be capable of mitigating an accident, barring a single failure.

The 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> Completion Time is justified because there is a limited range of break sizes, and therefore a lower probability for a small break LOCA which would require-piggy back operation.

G.1 and G.2 If a Required Action and associated Completion Time of Condition B, C, D, E, or F 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 the RCS temperature reduced to < 350°F 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.

H.1 I If two HPI trains are inoperable or two LPI-HPI flow paths are inoperable, the HPI System is incapable of performing its safety function and in a condition not explicitly addressed in the Actions for ITS 3.5.2. Thus, immediate plant shutdown in accordance with LCO 3.0.3 is required.

OCONEE UNITS 1, 2, & 3 B 3.5.2-11 BASES REVISION DATED 04/11/08 1

HPI B 3.5.2 BASES SURVEILLANCE SR 3.5.2.1 REQUIREMENTS Verifying the correct alignment for manual and non-automatic power operated valves in the, HPI flow paths provides assurance that the proper flow paths will exist for HPI operation. This SR does apply to the HPI suction header cross-connect valves, the HPI discharge cross-connect valves, the HPI discharge crossover valves, and the LPI-HPI flow path discharge valves (LP-1 5 and LP-1 6). 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. This Frequency has been shown to be acceptable through operating experience.

SR 3.5.2.2 With the exception of the HPI pump operating to provide normal makeup, the other two HPI pumps are normally in a standby, non-operating mode.

As such, the emergency injection flow path piping has the potential to develop voids and pockets of entrained gases. Venting the HPI pump casings periodically reduces the potential that such voids and pockets of entrained gases can adversely affect operation of the HPI System. This will also reduce 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. This Surveillance is modified by a Note that indicates it is not applicable to operating HPI pump(s) providing normal makeup. The 31 day Frequency takes into consideration the gradual nature of gas accumulation in the HPI piping and the existence of procedural controls governing system operation.

SR 3.5.2.3 Periodic surveillance testing of HPI 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. 5). SRs are specified in the Inservice Testing Program, which encompassesSection XI of the ASME Code.

OCONEE UNITS 1, 2, & 3 B 3.5.2-12 BASES REVISION DATED 04/11/08 1

HPI B 3.5.2 BASES SURVEILLANCE SR 3.5.2.4 and SR 3.5.2.5 REQUIREMENTS (continued) These SRs demonstrate that each automatic HPI valve actuates to the required position on an actual or simulated ESPS signal and that each HPI 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 part of the Inservice Testing Program.

SR 3.5.2.6 Periodic inspections of the reactor building sump suction inlet (for LPI-HPI flow path) 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 3.5.2.7 Periodic stroke testing of the HPI discharge crossover valves (HP-409 and HP-410) and LPI-HPI flow path discharge valves (LP-15 and LP-16) is required to ensure that the valves can be manually cycled from the Control Room. This test is performed on an 18 month Frequency. Operating experience has shown that these components usually pass the surveillance when performed at this Frequency. Therefore, the Frequency is acceptable from a reliability standpoint.

OCONEE UNITS 1, 2, & 3 B 3.5.2-13 BASES REVISION DATED 04/11/08 1

HPI B 3.5.2 BASES REFERENCES 1. 10 CFR 50.46.

2. UFSAR, Section 15.14.3.3.6.

3. 10 CFR 50.36.

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

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

6. Letter from R. W. Reid (NRC) to W. 0. Parker, Jr. (Duke) transmitting Safety Evaluation for Oconee Nuclear Station, Units Nos. 1, 2, and 3, Modifications to the High Pressure Injection System, dated December 13, 1978.

7. Letter from W. R. McCollum (Duke) to the U. S. NRC, "Proposed Amendment to the Facility Operating License Regarding the High Pressure Injection System Requirements," dated December 16, 1998.

OCONEE UNITS 1, 2, & 3 B 3.5.2-14 BASES REVISION DATED 04/11/08 1

CRACS B 3.7.16 B 3.7 PLANT SYSTEMS B 3.7.16 Control Room Area Cooling Systems (CRACS)

BASES BACKGROUND The CRACS provides temperature control for the control areas.

The control area is defined as the control; room, cable room, and equipment room for each unit. Units 1 and 2 have a shared control room, and Unit 3 has an independent control room. The cable and equipment rooms are independent for each unit. The control rooms, cable rooms, and equipment rooms for each unit contain vital electrical equipment, such as 125 VDC Vital I&C Power and 120 VAC Vital I&C Power, which is essential for achieving safe shutdown on the units. A control area portion is defined as a cable room, equipment room, or control room, for which a set of redundant CRVS cooling trains is required. The control area portions are listed in the table below. Through the use of alternative air flow paths, air handling units AHU-34 and AHU-35 provide redundant cooling to both Units 1 and 2 cable rooms.

The AHUs which cool the control areas are part of the CRVS for each unit. The Chilled Water System (WC) serves as the heat sink for the CRVS on all thrlee units. The WC System consists of two redundant cooling trains which serve all three units.

UFSAR Section 9.4.1 (Ref. 1) requires that redundant air conditioning and ventilation equipment be available to assure that no single failure of an active component within the CRVS and WC System will prevent proper control area environmental control. During a LOOP event, power will be temporarily lost to the equipment within these systems. Upon restoration of power the equipment will be required to restart. This restart makes the equipment susceptible to a single active failure. Without redundant cooling capability, acceptable temperatures within the control area could be exceeded. This could result in the potential failure of vital electrical equipment which is needed for safe shutdown of the units.

OCONEE UNITS 1, 2, & 3 B 3.7.16-1 BASES REVISION DATED 04/11/08 1

CRACS B 3.7.16 BASES BACKGROUND The following table identifies each portion of the CRVS where (continued) redundancy is required:

Table B 3.7.16-1 CRVS Redundant Equipment Control Area PortionI[ Associated CRVS Cooling Trains Unit 1&2 Control Room AHU-1 1 and AHU-1 2 Unit 1 Cable Room AHU-34 and AHU-35 Unit 1 Equipment Room AHU-22'and AHU-34 Unit 2 Cable Room AHU-34 and AHU-35 Unit 2 Equipment Room AHU-23 and AHU-35 Unit 3 Control Room AH Us 3-13 and 3-14 Unit 3 Cable Room AHUs 3-11 and 3-12 Unit 3 Equipment Room AHUs 3-15 and 3-16 A single train will provide the required temperature control. The CRACS operation to maintain control room temperatiure is discussed in the UFSAR, Section 9.4.1 (Ref. 1).

APPLICABLE The design basis of the CRACS is to maintain control area temperature SAFETY ANALYSES to ensure cooling of vital equipment.

The CRACS components are arranged in redundant trains. A single active failure of a CRACS component does not impair the ability of the system to perform as designed. The CRACS is designed to remove sensible and latent heat loads from the control area, including consideration of equipment heat loads to ensure equipment OPERABILITY.

The CRACS satisfies, Criterion 3 of the NRC Policy Statement.

OCONEE UNITS 1, 2, & 3 B 3.7.16-2 BASES REVISION DATED 04/11/08 1

CRACS B 3.7.16 BASES (continued)

LCO Two redundant trains of the CRACS and WC Systems train are required to be OPERABLE to ensure that at least one train in each system is available, assuming a single active failure disables the other train in one or both systems. Total system failure could result in the equipment operating temperature exceeding limits. A Train of CRVS consists of one of the redundant AHUs specified in Table B 3.7.16-1 for each of the three portions of the control area for an Oconee unit and associated ducts, dampers, instrumentation and controls. A single AHU can function as a component in more than one train on an Oconee unit and can function as a component on trains in multiple Oconee units. For example AHU-34, and its associated ducts, damper, instrumentation and controls, can simultaneously function as the AHU for a train of CRVS serving the Unit 1 cable room, the Unit 1 equipment room as well as the Unit 2 cable room.

The combination of AHU-34 and either AHU-1 1 or AHU-12 along with their associated equipment constitutes a combination of equipment which can satisfy the requirement for one train of CRVS for Unit 1. Additionally, AHU-34 can simultaneously serve as the AHU for the portion of a Unit 2 CRVS train serving the Unit 2 cable room. AHU-35 in combination with either AHU-1 1 or AHU-1 2 along with their associated equipment constitutes a combination of equipment which can satisfy the requirement for one train of CRVS for Unit 2.

For the Units 1 and 2 cable and equipment rooms, a system of motorized dampers is provided to allow AHU-34 and AHU-35 to provide cooling to the opposite unit's cable and equipment rooms in the event of the loss of one of the AHU's. The flow path for cooling is accomplished by closing redundant dampers between the unit's cable and equipment rooms upon loss of the opposite units cable room AHU.

If AHU-34 fails, the dampers between the Unit 2 cable and equipment rooms will close, allowing AHU-35 to cool both Units 1 and 2 cable and equipment rooms providing AHU-22 and AHU-23 are operating. If one or both of the dampers in the flow path, fail open, then both AHU's are inoperable for Unit 1. If both dampers close, an adequate flow path for OPERABILITY is maintained even if one of two motor operated dampers on Unit 1 fail closed. If the Unit 2 dampers fail closed, OPERABILITY is not affected for the AHU-34 failure scenario. OPERABILITY is not maintained if one or both of the fire dampers between cable rooms or equipment rooms is closed. Compensatory measures, such as opening the damper must be taken to maintain OPERABILITY.

If AHU-35 fails, the dampers between the Unit 1 cable and equipment rooms will close, allowing AHU-34 to cool both Units 1 and 2 cable and equipment rooms providing AHU-22 and AHU-23 are operating. If one or both of the dampers in the flow path, fail open, then both AHU's are OCONEE UNITS 1, 2, & 3 B 3.7.16-3 BASES REVISION DATED 04/11/08 1

CRACS B 3.7.16 BASES (continued)

LCO inoperable for Unit 2. If both dampers close, an adequate flow path for (continued) OPERABILITY is maintained even if one of two motor operated dampers on Unit 2 fail closed. If the Unit 1 dampers fail closed, OPERABILITY is not affected for the AHU-35 failure scenario. OPERABILITY is not maintained if one or both of the fire dampers between cable rooms or equipment rooms is closed. Compensatory measures, such as opening the damper and posting a fire watch must be taken to maintain OPERABILITY.

The CRACS is considered OPERABLE when the individual components that are necessary to maintain control area temperature are OPERABLE in both trains of CRVS and WC System. Each CRVS train listed in Table B 3.7.16-1 includes the associated ductwork, instrumentation, and air handling unit, which includes the fan, fan motor, cooling coils, and isolation dampers. Each WC train consists of a chiller, chilled water pump, condenser service water pump, and associated controls. Although each chilled water pump is normally associated with, and aligned to, a specific chiller, any OPERABLE chilled water pump maybe aligned to any OPERABLE chiller to maintain one OPERABLE train when a component has been removed from service. The two redundant trains can include a temporarily installed full-capacity control area cooling train. Any temporary cooling train shall have a power source with availability equivalent to the source of the permanently installed train. A temporary cooling train power source with equivalent availability shall include procedural controls for:

1. Normal Auxiliary power (e.g. B4T-7) for normal operation.

2. Swapping to a Keowee backed power supply (e.g. 3TD-15) following a LOOP.

In addition, the'CRACS must be OPERABLE to the extent that air circulation can be maintained.

APPLICABILITY In MODES 1, 2, 3, 4, and during movement of recently irradiated fuel assemblies (i.e., fuel that has occupied part of a critical reactor core within the previous 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />), the CRACS must be OPERABLE to ensure that the control area temperature will not exceed equipment OPERABILITY requirements.

OCONEE UNITS 1, 2, & 3 B 3.7.16-4 BASES REVISION DATED 04/11/08

CRACS B 3.7.16 BASES (continued)

ACTIONS A.1 With one CRVS train inoperable for the control area, action must be taken to restore the CRVS train to OPERABLE status within 30 days. In this Condition, the remaining OPERABLE CRVS train is adequate to maintain the control area temperature within limits. However, the overall reliability is reduced because a failure in the OPERABLE CRVS train could result in a loss of CRVS cooling function. The 30 day Completion Time is based on the low probability of a loss of CRVS cooling component and the time necessary to perform repairs to CRVS cooling equipment.

B. 1 With one WC train inoperable for a control area portion, action must be taken to restore the WC train to OPERABLE status within 30 days. In this Condition, the remaining OPERABLE WC train is adequate to maintain the control area portion temperature within limits. However, the overall reliability is reduced because a failure in the OPERABLE WC train could result in a loss of CRACS cooling function. The 30 day Completion Time is based on the low probability of a loss of WC cooling component, and on the time necessary to perform repairs to WC cooling equipment.

C.1 With the control room area air temperature outside its limit, action must be taken to restore the air temperature to within the limit within 7 days. If the control room area air temperature exceeds its limit, the ability of a single train of CRACS to maintain control room area temperature may be affected. The Completion Time of 7 days is reasonable considering the remaining CRACS train available to perform the required temperature control function and the low probability of an event occurring that would require the CRACS operation during that time.

The Required Actions are modified by a Note that states LCO 3.0.4 is not applicable. In consideration of the redundant CRACS train available, the small variation in temperature expected between 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> surveillances, and the marginal impact small temperature variations may have on the ability of a CRACS train to maintain the control room temperature within limits, an exception to LCO 3.0.4 is applicable for this condition.

OCONEE UNITS 1, 2, & 3 B 3.7.16-5 BASES REVISION DATED 04/11/08 1

CRACS B 3.7.16 BASES ACTIONS D.1 and D.2 (continued)

If the Required Actions and associated Completion Times of Conditions A, B, or C are not met in MODE 1, 2, 3, or 4, the unit must be placed in a MODE in which the LCO does not apply. To achieve this status, the unit must be placed in 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 in MODE 5 within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-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 without challenging unit systems.

E.1 and E.2 During movement of recently irradiated fuel, if the inoperable CRACS train cannot be restored to OPERABLE status within the required Completion Time, the OPERABLE CRACS train must be placed in operation immediately. This action ensures that the remaining train is OPERABLE, that no failures preventing actuation will occur, and that any active failure will be readily detected. An alternative to Required Action E.1 is to immediately suspend activities that could release radioactivity that might require the isolation of the control room. This places the unit in a condition that minimizes accident risk. This does not preclude the movement of fuel to a safe position.

F. 1 If both CRVS trains or both WC trains are inoperable during MODE 1, 2, 3 or 4, the CRACS may not be capable of performing the intended function and the unit is in a condition outside the accident analyses.

Therefore, LCO 3.0.3 must be entered immediately.

-G.1 During movement of recently irradiated fuel assemblies, with two CRACS trains inoperable, action must be taken to immediately suspend activities that could release radioactivity that might require isolation of the control room. This places the unit in a condition that minimizes accident risk.

This does not preclude the movement of fuel to a safe position.

OCONEE UNITS 1, 2, & 3 B 3.7.16-6 BASES REVISION DATED 04/11/08 I

CRACS B 3.7.16 BASES SURVEILLANCE SR 3.7.16.1 REQUIREMENTS This SR verifies that the heat removal capability of the system is sufficient to maintain the temperature in the control room and cable room at or below 80°F and maintain the temperature in the electrical equipment room at or below 85TF. The temperature is determined by reading gauges in each area or computer points which are considered representative of the average area temperature. These temperature limits are based on operating history and are intended to provide an indication of degradation of the cooling systems. The limits are conservative with respect to equipment operability temperature limits.

The values for the SR are values at which the system is removing sufficient heat to meet design requirements (i.e., OPERABLE) and sufficiently above the values associated with normal operation during hot weather. The temperature in the equipment room is typically slightly higher than the temperature in the control room or cable room. Because of that, a higher value is specified for this area. The 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> Frequency is appropriate since significant degradation of the CRACS is slow and is not expected over this time period.

REFERENCES 1. UFSAR, Section 9.4.1.

OCONEE UNITS 1, 2, & 3 B 3.7.16-7 BASES REVISION DATED 04/11/08 1

Attachment #2 Markup of current TSB

HPI B 3.5.2 BASES LCO taking suction from the BWST through the suction header valve associated (continued) with that train upon an ESPS signal. For example:

1) if HPI pump *B"is being credited as part of HPI train 4A," then it must be capable of taking suction through HP-24 upon an ESPS signal; or

2) if HPI pump 'B" is being credited as part of HPI train "B," then it must be capable of taking suction through HP-25 upon an ESPS signal.

The safety grade flow indicator associated with the normal discharge valve is required to be OPERABLE to support the associated HPI train's automatic OPERABILITY.

To support HPI pump OPERABILITY, the piping, valves and controls which ensure the HPI pump can take suction from the BWST upon an ESPS signal are required to be OPERABLE.

To support HPI discharge crossover valve OPERABILITY, the safety grade flow indicator associated with the HPI discharge crossover valve is required to be OPERABLE.

To support LPI-HPI flow path OPERABILITY, each flow path must be capable of being supplied by an OPERABLE LPI train. When capable of being supplied by an OPERABLE LPI train:

1) An LPI-HPI flow path, including the piping, instruments, valves and controls, must be in-place to ensure the capability to transfer suction to the reactor building sump from the control room. Within the LPI-HPI flow path are the LPI discharge valves to the LPI-HPI flow path (LP-1 5 and LP-1 6).

2) The LPI discharge valves to the LPI-HPI flow path must be capable of being (,u-,, .... . W,) opened for the LPI-HPI flow path to be OPERABLE.

The OPERABILITY requirements regarding the L stem are addressed in LCO 3.5.3, "Low Pressure Injection (LPI)."

As part of the LPI-HPI flow path, the piping, instruments, valves and controls upstream of LP-15 and LP-16 are part of the LPI system and are subject to LCO 3.5.3 (Low Pressure Injection system) requirements. The piping, instruments, valves and controls downstream of and including LP-15 and LP-1 6, are part of the HPI system and are subject to LCO 3.5.2 (High Pressure Injection system) requirements.

OCONEE UNITS 1, 2, &3 B 3.5.2-5 BASES REVISION DATED 03/31/05 I

HPI B 3.5.2 BASES LCO When a LPI-HPI flow path is inoperable due to the flow path's associated (continued) LPI train being inoperable for maintenance only, the piggyback line and associated components may also be inoperable for greater than 72-hours up to the associated LPI train's maximum allowed outage time of 7-days.

For this scenario, any valve along the piggyback line flowpath can be used as an isolation boundary, with power removed as necessary, but no physical work is allowed to be performed on any component along the piggyback fine flowpath without entering the applicable TS LCO condition.

This is allowed because with an associated LPI train inoperable, there is no water source for the LPI-HPI piggyback function. This support (LPI train) and supported (LPI-HPI piggyback) relationship is subject to the requirements of TS LCO 3.0.6.

During an event requiring HPI actuation, a flow path is provided to ensure an abundant supply of water from the BWST to the RCS via the HPI pumps and their respective discharge flow paths to each of the four cold leg injection nozzles and the reactor vessel. In the recirculation phase, this flow path isim transferredto take its supply from the reactor building sump and to supply borated wate to the RCS via the LPI-HPI flow ath (piggy-back mode). t' "* . -

The OPERABIUTY of the HPI System mustbe main ained to ensure that no single active failure can disable both HPI trains. Additionally, while the HPI System was not designed to cope with passive failures, the HPI trains must be maintained independent to the extent possible during normal operation. The NRC approved exception to this principle is cross-connecting the HPI suction headers during normal operation (Ref. 6).

APPLICABILITY In MODES 1 and 2, and MODE 3 with RCS temperature > 3500F, the HPI System OPERABILITY requirements for the small break LOCA are based on analysis performed at 100% RTP. The HPI pump performance is based on the small break LOCA, which establishes the pump performance curve.

Mode 2 and MODE 3 with RCS temperature > 350OF requirements are bounded by the MODE 1 analysis.

In MODE 3 with RCS temperature _350°F and in MODE 4, the probability of an event requiring HPI actuation is significantly lessened. In this operating condition, the low probability of an event requiring HPI actuation and the LCO 3.5.3 requirements for the LPI System provide reasonable assurance that the safety injection function is preserved.

In MODES 5 and 6, unit conditions are such that the probability of an event requiring HPI injection is extremely low. Core cooling requirements in MODE 5 are addressed by LCO 3.4.7, "RCS Loops - MODE 5, Loops I

OCONEE UNITS 1, 2, &3 B 3.5.2-6 BASES REVISION DATED 03/31/05 I

HPI B 3.5.2 BASES SURVEILLANCE SR 3.5.2.4 and SR 3.5.2.5 REQUIREMENTS (continued) These SRs demonstrate that each automatic HPI valve actuates to the required position on'an actual or simulated ESPS signal and that each HPI 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 part of the Inservice Testing Program.

SR 3.5.2.6 Periodic inspections of the reactor building sump suction inlet (for LPI-HPI flow path) 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 3.5.2.7 Periodic stroke testing of the HPI discharge crossover valves (HP-409 and HP-41 0) and LPI-HPI flow path discharge valves (LP-1 5 and LP-1 6 is recuired to ensure that the valves can be manually cycledoý ý OWN A /-T his test is performed on an 18 month Frequency.

Operating expenience has shown that these components usually pass the surveillance when performed at this Frequency. Therefore, the Frequency is acceptable from a reliability standpoint.

OCONEE UNITS 1, 2, & 3 B 3.5.2-13 BASES REVISION DATED 03/31/05 I

CRACS B 3.7.16 B 3.7 PLANT SYSTEMS B 3.7.16 Control Room Area Cooling Systems (CRACS)

BASES BACKGROUND The CRACS provides temperature control for the control areas.

The control area is defined as the control room, cable room, and equipment room for each unit. Units 1 and 2 have a shared control room, and Unit 3 has an independent control room. The cable and equipment rooms are independent for each unit. The control rooms, cable rooms, and equipment rooms for each unit contain vital electrical equipment, such as 125 VDC Vital I&C Power and 120 VAC Vital I&C Power, which is essential for achieving safe shutdown on the units. A control area portion is defined as a cable room, equipment room, or control room, for which a set of redundant CRVS cooling trains is required. The control area portions are listed in the table below. Through the use of alternative air flow paths, air handling units AHU-34 and AHU-35 provide redundant cooling to both Units 1 and 2 cable rooms.

The AHUs which cool the control areas are part of the CRVS for each unit. The Chilled Water System (WC) serves as the heat sink for the CRVS on all three units. The WC System consists of two redundant cooling trains which serve all three units.

UFSAR U Setcion Ref. 1) requires that redundant air conditioning an niaone t be available to assure that no single failure of an active component within the CRVS and WC System will prevent proper control area environmental control. During a LOOP event, power will be temporarily lost to the equipment within these systems. Upon restoration of power the equipment will be required to restart. This restart makes the equipment susceptible to a single active failure. Without redundant cooling capability, acceptable temperatures within the control area could be exceeded. This could result in the potential failure of vital electrical equipment which is needed for safe shutdown of the units.

OCONEE UNITS 1, 2, & 3 B 3.7.16-1 BASES REVISION DATED 04/24/03 I

CRACS B 3.7.16 BASES BACKGROUND The following table identifies each portion of the CRVS where (continued) redundancy is required:

Table B 3.7.16-1 CRVS Redundant Equipment Control Area Portion Associated CRVS Cooling Trains Unit 1&2 Control Room AHU-1 1 and AHU-1 2 Unit 1 Cable Room AHU-34 and AHU-35 Unit 1 Equipment Room AHU-22 and AHU-34 Unit 2 Cable Room AHU-34 and AHU-35 Unit 2 Equipment Room AHU-23 and AHU-35 Unit 3 Control Room AHUs 3-13 and 3-14 Unit 3 Cable Room AHUs 3-11 and 3-12 Unit 3 Equipment Room AHUs 3-15 and 3-16 A single train will provide the required temperature control. The CRACS operation to maintain control m temperature is discussed in the UFSAR, Section 9.4.1"(Ref"*.*.

APPLICABLE The design basis of the CRACS is to maintain control area temperature SAFETY ANALYSES to ensure cooling of vital equipment.

The CRACS components are arranged in redundant trains. A single active failure of a CRACS component does not impair the ability of the system to perform as designed. The CRACS is designed to remove sensible and latent heat loads from the control area, including consideration of equipment heat loads to ensure equipment OPERABILITY.

The CRACS satisfies Criterion 3 of the NRC Policy Statement.

OCONEE UNITS 1, 2, & 3 B 3.7.16-2 BASES REVISION DATED 04/24/03 1

CRACS B 3.7.16 BASES SURVEILLANCE SR 3.7.16.1 REQUIREMENTS This SR verifies that the heat removal capability of the system is sufficient to maintain the temperature in the control room and cable room at or below 80°F and maintain the temperature in the electrical equipment room at or below 85°F. The temperature is determined by reading gauges in each area or computer points which are considered representative of the average area temperature. These temperature limits are based on operating history and are intended to provide an indication of degradation of the cooling systems. The limits are conservative with respect to equipment operability temperature limits.

The values for the SR are values at which the system is removing sufficient heat to meet design requirements (i.e., OPERABLE) and sufficiently above the values associated with normal operation during hot weather. The temperature in the equipment room is typically slightly higher than the temperature in the control room or cable room. Because of that, a higher value is specified for this area. The 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> Frequency is appropriate since significant degradation of the CRACS is slow and is not expected over this time period.

REFERENCES OCONEE UNITS 1, 2, & 3 B 3.7.16-7 Amendment Nos. 338, 339, & 339 1