ML033240039

Transmittal of Technical Specifications Bases Unit 2 Manual

ML033240039
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Site:	Susquehanna
Issue date:	11/07/2003
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To:	Document Control Desk, Office of Nuclear Reactor Regulation
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SUSQUEHANNA STEAM ELECTRIC STAIION LIST OF EFFECTIVE SECTIONS (TECHNICAL SPECIFICATIONS BASES)

\Section Title Revision TOC Table of Contents 2 B 2.0 SAFETY LIMITS BASES Page TS / B 2.0-1 1 Pages TS / B 2.0-2 and TS B 2.0-3 2 Page TS / B 2.0-4 3 Page TS / B 2.0-5 1 Pages B 2.0-6 through B 2.0-8 0 B 3.0 LCO AND SR APPLICABILITY BASES 0 Pages B 3.0-1 through B 3.0-7 0 Pages TS / B 3.0-8 and TS / B 3.0-9 1 1\}

Pages B 3.0-10 through B 3.0-12 0 Pages TS / B 3.0-13 through TS / B 3.0-15 1 B 3.1 REACTIVITY CONTROL BASES Pages B 3.-1-1 through B 3.1-5 / 0 Pages TS / B 3.1-6 and TS B 3.1-7 1 Pages B 3:1-8 through B 3.1-27, - 0 PageTS/B3.1-28 1 Pages B 3.1-29 through B 3.10,36 0 Page TS / B 3.1-37 <K. .

Pages B 3.1-3 thruh B15 N...0 B 3.2 POWER DISTRIBUTION LiMITS BASES Pages TS / B 3.2 thoUgh TS I B 3.2-4 . -. 1 Pages TS / B 3.2A5 and S /B 3.2-6 .2 Page TS / B,3.2-7\ -1 Pages TS /B32-8and TS I B 3.2-9 2 PagesTS i3.y10'through TS / B 3.2-19 1 B 3.3 INSTR MENTATION PagesTS lB 3;3-1 through TS / B 3.3-10 1 Page TS / B 3.3-11 2 Pages TS / B 3.3-12 through TS / B 3.3-27 1 Pages TS / B 3.3-28 through TS / B 3.3-30 2 Page TS / B 3.3-31 1 Pages TS / B 3.3-32 and TS / B 3.3-33 2 Pages TS / B 3.3-34 through TS I B 3.3-54 1 Pages B 3.3-55 through B 3.3-63 0 Pages TS / B 3.3-64 and TS B 3.3-65 2 Page TS / B 3.3-66 4 Page TS / B 3.3-67 3 OE- eiin4 SUQUHAN - NT2TI

- SUSQUEHANNA - UNIT 2 TS B LOES-1 Revision 46

~~~~~7..I SUSQUEHANNA STEAM ELECTRIC STATION USTOF EFFECTIVE SECTIONS (TECHNICAL SPECIFICATIONS BASES)

.ecio Title Revision Page TS / B 3.3-68 4 Pages TS / B 3.3-69 and TS I B 3.3-70 3 Pages TS / B 3.3-71 through TS / B 3.3-75 2 Page TS / B 3.3-75a 4 Pages TS / B 3.3-75b through TS / B 3.3-75c 3 Pages B 3.3-76 through B 3.3-91 0 Pages TS / B 3.3-92 through TS / B 3.3-103 ' . 1 Page TS / B 3.3-104 2 Pages TS / B 3.3-105 and TS / B 3.3-106 1 Page TSB 3.3-107 2 Page TS / B 3.3-108 *1 Page TS / B 3.3-109 2 Pages TS / B 3.3-110 through TS / B 3.3-115 1 Pages TS / B 3.3-116 through TS / B 3.3-118 2 Pages TS / B 3.3-119 through TS / B 3.3-123 1 PageTS/B3.3-124 2 Page TS / B 3.3-124a . .0 Pages TS / B 3.3-125 and TS I B 3.3-126 1 Page TS / B 3.3-127 2 Pages TS / B 3.3-128 through TS / B 3.3-131 1 Page TS / B 3.3-132 _ .2 I Pages TS / B 3.3-133 and TS I B 3.3-134 Pages B 3.3-135 through B 3.3-137 .. . ' O Page TS / B 3.3-138

• 0I Pages B 3.3-139 through B 3.3-149.

Pages TS/ B 3.3-150 through TS I B 3.3-162 .. -.. _ :1 Page TS / B 3.3-163 -

Pages TS / B 3.3-164 through TS / B 3.3-177 1 Pages TS / B 3.3-178 and TS I B 3.3-179 . . 2 Page TS / B 3.3-179a 1 Pages TS / B 3.3-180 through TS I B 3.3-191 1 Pages B 3.3-192 through B 3.3-220 0 B 3.4 REACTOR COOLANT SYSTEM BASES Pages TS / B 3.4-1 and TS / B 3.4-2 1 Pages TS / B 3.4-3 through TS / B 3.4-6 2 Page TS / B 3.4-7 1 Pages TS / B 3.4-8 and TS I B 3.4-9 2 Pages B 3.4-10 through B 3.4-14 0 Page TS / B 3.4-15 1 Pages TS / B 3.4-16 and TS / B 3.4-17 2 PageTS /B 3.4-18 1 Pages B 3.4-19 through B 3.4-28 0 Revision 46 TSIBLOES-2 UNIT 2 SUSQUEHANNA - UNIT 2 TS / B LOES-2 Revision 46

SUSQUEHANNA STEAM ELECTRIC STATION UST OF EFFECTIVE SECTIONS (TECHNICAL SPECIFICATIONS BASES) 11%)Section -Title Revision Page TS / B 3.4-29 1 Pages B 3.3-30 through B 3.3-48 0 Page TS / B 3.4-49 2 Page TS / B 3.4-50 1 Page TS / B 3.4-51 .2 Pages TS / B 3.4-52 and TS I B 3.-53 1 Pages TS / B 3.4-54 and TS I B 3.4-55 2 Pages TS / B 3.4-56 through TS B 3.4-60 1 B 3.5 ECCS AND RCIC BASES Pages TS I B 3.5-1 and TS / B 3.5-2 1 Page TS I B 3.5-3 2 Pages TS / B 3.54 through TS / B 3.5-10 1 Page TS I B 3.5-11 2 Pages TS B 3.5-12'through TS / B 3.5-14 ' 1 Pages TS I B 3.5-15 through TS / B.3.5-17 2 Page TS I B 3.18 1 Pages B 3.5-19 through B 3.5-24 0 Page TS I B 3.5-25 1 Pages B 3.5-26 through B 3.5-31 0 K'Sc 3.6 CONTAINMENT SYSTEMS BASES Page TS / B 3.6-1 2 Page TS / B 3.6-1 a .3 Pages TS / B 3.6-2 through TS I B 3.6-5 2 Page TS / B 3.6-6 Pages TS / B 3.6-6a and TS I B 3.6-6b Page TS I B 3.6-6c .- ~~~ 20 Pages B 3.6-7 through B 3.6-14 0 Page TS I B 3.6-15 3 Pages TS I B 3.6-15a and TS I B 3.6-1 Sb 0 Page TS / B 3.6-16 1 Page TS I B 3.6-17 2 Page TS I B 3.6-17a 0 Pages TS I B 3.6-18 and TS I B 3.6-19 I Page TS / B 3.6-20 2 Page TS / B 3.6-21 3 Pages TS I B 3.6-21a and TS I B 3.6-21b 0 Pages TS / B 3.6-22 and TS / B 3.6-23 2 Pages TS / B 3.6-24 through TS I B 3.6-26 1 Page TS I B 3.6-27 3 Page TS / B 3.6-28 6 Page TS / B 3.6-29 3 SUSQUEHANNA - UNIT 2 TS /B LOES-3 Revision 46

SUSQUEHANNA STEAM ELECTRIC STATION LIST OF EFFECTIVE SECTIONS (TECHNICAL SPECIFICATIONS BASES)

OJ Section Title Revision Page TS / B 3.6-29a 0 Page TS / B 3.6-30 2 Page TS / B 3.6-31 3 Pages-TS / B 3.6-32 through TS / B 3.6-34 1 Pages TS / B 3.6-35 through TS / B 3.6-37 2 Page TS / B 3.6-38 I Page TS / B 3.6-39 4 Pages B 3.6-40 through B 3.6-42 0 Pages TS / B 3.6-43 through TS / B 3.6-50 1 Page TS / B 3.6-51 2 Pages B 3.6-52 through B 3.6-62 0 Page TS / B 3.6-63 . 1 Pages B 3.6-64 through B 3.6-82 0 Page TS / B 3.6-83 2 Pages TS / B 3.6-84 through TS / B 3.6-87 _ 1 Page TS / B 3.6-87a Page TS / B 3.6-88 2 Pages TS / B 3.6-89 through TS / B 3.6-99 1 Pages B 3.6-100 through B 3.6-106 0 3 3.7 PLANT SYSTEMS BASES Pages TS / B 3.7-1 through TS / B 3.7-6. 2 Page TS / B 3.7-6a 2 Pages TS / B 3.7-6b and TS / B 3.7-6c *0 Pages TS / B 3.7-7 and TS / B 3.7-8 1 Pages B 3.7-9 through B 3.7-11 . .. ..

Pages TS / B 3.7-12 and TS / B 3.7-13 Pages TS / B 3.7-14 through TS / B 3.7-18 Page TS / B 3.7-18a 0 Pages TS / B 3.7-19 through TS / B 3.7-26 1 Pages B 3.7-24 through B 3.7-26 0 Pages TS / 3.7-27 through TS / B 3.7-29 *1 Pages B 3.7-30 through B 3.7-33 0 B 3.8 ELECTRICAL POWER SYSTEMS BASES Pages B 3.8-1 through B 3.8-4 0 Page TS / B 3.8-5 I Pages B 3.8-6 through B 3.8-8 0 Pages TS / B 3.8-9 through TS / B 3.8-11 I Pages B 3.8-12 through B 3.8-18 0 PageTS / B 3.8-19 I Pages B 3.8-20 through B 3.8-22 0 Page TS / B 3.8-23 I SUSQUEHANNA - UNIT 2 TS /B LOES-4 Revision 46

SUSQUEHANNA STEAM ELECTRIC STATION LUST OF EFFECTIVE SECTIONS (TECHNICAL SPECIFICATIONS BASES)

Section Title Revision Page B 3.8-24 0 Pages TS I B 3.8-25 and TS / B 3.8-26 1 Pages B 3.8-27 through B 3.8-37 0 Page TS / B 3.8-38 1 Pages TS / B 3.8-39 through TS I B 3.8-55 0 Pages TS I B 3.8-56 through TS I B 3.8-64 1 Page TS / B 3.8-65 *2 Page TS / B 3.8-66 2 Pages TS / B 3.8-67 through TS I B 3.8-68 1 Page fS/ B 3.8-69 2 Pages B 3.8-70 through B 3.8-99 0 B 3.9 REFUELING OPERATIONS BASES Pages TS / B 3.9-1 and TS / B 3.9-2 1 Page TS / B 3.9-2a Pages TS / B 3.9-3 and TS / B 3.9-4 1 Pages B 3.9-5 through B 3.9-30 0 B 3.10 SPECIAL OPERATIONS BASES PageTS/B3.10-1 1 Pages B 3.10-2 through B 3.10-32 Page TS / B 3.10-33 Pages B 3.10-34 through B 3.10-38 . . ' *1 O Page TS / B 3.10-39 NFM TSB2 text LOES TSIBLOES-5 Revision 46 SUSQUEHANNA - UNIT -

UNIT 22 TS /B LOES-5 Revision 46

PPL Rev. 1 '

Recirculation Loops Operating B C B 3.4.1 B 3.4 ' REACTOR COOLANT SYSTEM (RCS)

B 3.4.1 Recirculation Loops Operating BASES -

BACKGROUND The Reactor Coolant Recirculation System is designed to provide a forced coolant flow through the core to remove heat from the fuel. The forced coolant flow removes more heat from the fuel than would be possible with just natural circulation. The forced flow, therefore, allows operation at significantly higher power than would otherwise be possible. The recirculation system also controls reactivity over a wide span of reactor power by varying the recirculation flow rate to control the void content of the moderator. The Reactor Coolant Recirculation System consists of two recirculation pump loops external to the reactor vessel. These loops provide the piping path for the driving flow of water to the reactor vessel jet pumps. Each external loop contains one variable speed motor driven recirculation pump, a motor generator (MG) set to control pump speed and associated piping, jet pumps, valves, and instrumentation. The recirculation pump, piping, and valves are part of the reactor coolant pressure boundary and are located inside the drywell structure. The jet pumps are reactor vessel internals.

The recirculated coolant consists of saturated water from the steam separators and dryers'that has been subcooled by'incoming feedwater.

This water passes down the annulus between the reactor vessel wall and the core shroud. A portion of the coolant flows from the vessel, through the two external recirculation loops, and becomes the driving flow for the jet pumps. Each of the two external recirculation loops-discharges high pressure flow into an external manifold, from which individual recirculation inlet lines are routed to the jet pump risers within the reactor vessel. The remaining'portion of the coolant mixture in the annulus becomes the suction flow for the jet pumps. This flow enters the jet pump at suction inlets and is accelerated by the driving flow. The drive flow and suction flow are mixed in the jet pump throat section. The total flow then passes

-through the jet pump diffuser section into the area below the core (lower plenum), gaining sufficient head in the process to drive the required flow upward through the core. The subcooled water enters the bottom of the fuel channels and contacts the fuel (continued)

SUSQUEHANNA - UNIT 2 TS / B3.4-1 Revision 2

PPL Rev. 1 Recirculation Loops Operating B 3.4.1 BASES BACKGROUND cladding, where heat is transferred to the coolant. As it rises, the coolant (continued) begins to boil, creating steam voids within the fuel channel that continue

- until the coolant exits the core. Because of reduced moderation, the steam voiding introduces negative reactivity that must be compensated for to maintain or to increase reactor power. The recirculation flow control allows operators to increase recirculation flow-and sweep some of the voids from the fuel channel, overcoming the negative reactivity void effect.

Thus, the reason for having variable recirculation flow is to compensate for reactivity effects of boiling over a wide range of power generation without having to move control rods and disturb desirable flux patterns.

Each recirculation loop is manually started from the control room. The MG

-set provides regulation of individual recirculation loop drive flows. The flow in each loop is manually controlled.

APPLICABLE The operation of the Reactor Coolant Recirculation System is an initial SAFETY ..condition assumed in the design basis loss of coolant accident (LOCA)

ANALYSES (Ref. 1). During a LOCA caused by.a recirculation loop pipe break, the intact loop is assumed to provide coolant flow during the first few seconds of the accident. The initial core flow decrease is rapid because the recirculation pump in the broken loop ceases tolpump reactor coolant to the vessel almost immediately. The pump in the intact loop coasts down relatively slowly. This pump coastdown governs the core flow response for the next several seconds until the jet pump suction is uncovered (Ref. 1). The analyses assume that both loops re operating at the same flow prior to the accident. However, the LOCA analysis-was reviewed for.

the case with a flow mismatch between the two loops, with the pipe break assumed to be in the loop with the higher flow. While the flow coastdown and core response are potentially more severe in this assumed case (since the intact loop starts at a lower flow rate and the:.core'response is the same as if both loops were operating at a lower flow rate), a small mismatch has been determined to be acceptable based on engineering judgement. The recirculation system is also assumed to have sufficient flow coastdown characteristics to maintain fuel thermal margins during abnormal operational transients (Ref. 2), which are analyzed in Chapter 15 of the FSAR.

(continued)

SUSQUEHANNA - UNIT 2 TS/ B3.4-2 Revision 2

- . . .- - - --- - --. - . .. . . .r_ I. .- -- __ --- .I. , . .-- - - ____ .- . -I .

PPL Rev. 1 Recirculation Loops Operating B 3.4.1 BASES APPLICABLE Plant specific LOCA analyses have been performed assuming only one SAFETY operating recirculation loop. These analyses have demonstrated that, in ANALYSES the event of a LOCA caused by a pipe break in the operating recirculation (continued) -_loop, the Emergency Core Cooling System response will provide adequate core cooling, provided that the APLHGR limit for SPC ATRIUM-10 fuel is modified.

The transient analyses of Chapter 15 of the FSAR have also been performed for single recirculation loop operation and demonstrate sufficient flow coastdown characteristics to maintain fuel thermal margins during the abnormal operational transients analyzed provided the MCPR requirements are modified. During single recirculation loop operation, modification to the Reactor Protection System (RPS) average power range monitor (APRM) instrument setpoints is also required to account for the different relationships between recirculation drive flow and reactor core flow. The APLHGR, LHGR and MCPR setpoints for single loop operation are specified in the COLR. The APRM flow biased simulated THERMAL POWER setpoint is in LCO 3.3.1.1, "Reactor Protection System (RPS) Instrumentation." In addition, a restriction on recirculation pump speed is incorporated to address Reactor Vessel Internals vibration concerns and assumptions in the event analysis.

General Design Criterion-10 (GDC 10) requires that the reactor core be designed with appropriate margin to assure that fuel design limits will not be exceeded during any condition of normal operation including anticipated operational occurrences. -GDC 12 requires assurance that power oscillations which can result in conditions exceeding specified acceptable fuel design limits are either not possible or can be reliably and readily detected and suppressed. The ACTIONS in this section ensure compliance with GDC 12, thereby providing protection from exceeding the fuel MCPR safety limit BWR cores may exhibit thermal-hydraulic reactor instabilities in high power and low flow portions of the core power to flow operating domain.

GDC12 requires assurance that power oscillations which can result in conditions exceeding specified acceptable fuel design limits are either not possible or (continued)

SUSQUEHANNA - UNIT 2 . TS/ 34-3 Revision 2

• . ^,.. .;.PPL Rev. 1 Recirculation Loops Operating B3.4.1 BASES APPLICABLE can be reliably and readily detected and suppressed. This LCO and

'SAFETY - associated ACTIONS ensure compliance with GDC 12 by establishing ANALYSIS conservative boundaries that limit the impact of thermal-hydraulic (continued) instabilities.

This LCO and ACTIONS establish power/flow regions and associated requirements and restrictions consistent with References 3, 4, and 5 provide a conservative boundary for plant operation to ensure compliance with GDC 12 and that thermal-hydraulic instabilities are avoided.

Recirculation loops operating satisfies Criterion 2 of the NRC Policy Statement (Ref. 6).

LCO Two recirculation loops are required to be in operation with their flows matched within the limits specified in SR 3.4.1.1 to ensure that during a LOCA caused by a break of the piping of one recirculation loop the assumptions of the LOCA analysis are satisfied. With the limits specified in SR 3.4.1.1 not met, the recirculation loop with the lower flow must be-considered not in operation. With only one recirculation loop in operation, modifications to the required APLHGR limits (LCO 3.2.1, "AVERAGE PLANAR LINEAR HEAT-GENERATION RATE"), LHGR limits (LCO 3.2.3, "LINEAR HEAT GENERATION RATE (LHGR)"), MCPR limits (LCO 3.2.2, "MINIMUM CRITICAL POWER RATIO (MCPR)'), and APRM Flow Biased Simulated Thermal Power-High setpoint (LCO 3.3.1.1) may be applied to allow continued operation consistent with the safety.analysis assumptions.

Furthermore, restrictions are placed on recirculation pump speed to assure the initial assumptions of the event analysis are maintained.

In addition, during two-loop and single-loop operation, the combination of core flow and THERMAL POWER must be outside of Region I or 11of the Power / Flow map specified in the COLR to limit the impact of core thermal hydraulic oscillations.

Regions I and 11are a composite of the improved BWR Owners' Group Guidelines for Stability Interim Corrective Action (ICA) (Reference 4) and unit I cycle specific stability calculations performed using NRC approved methods (Reference 5). The regions are drawn such that they bound both the improved ICAs and the cycle specific stability calculations. Operation outside Regions I and 11provide a high degree of confidence that reactor instabilities will not occur or will not be of sufficient severity to violate the MCPR safety limit.

-^> - (continued)

SUSQUEHANNA - UNIT 2 TS I B 3.4-4 Revision 2

PPL Rev. 1 Recirculation Loops Operating B 3.4.1 BASES LCO The LCO is modified by a Note that allows up to 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> to establish the (continued) required limits and setpoints after a change from two recirculation loops operation to single recirculation loop operation. If the limits and setpoints are not in compliance with the applicable requirements at the end of this period, the ACTIONS required by the applicable specifications must be implemented. This time is provided to stabilize operation with one recirculation loop by: limiting flow in the operating loop, limiting total THERMAL POWER, monitor APRM and local power range monitor (LPRM) neutron flux noise levels; and, fully implementing and confirming the required limit and setpoint modifications.

APPLICABILITY In MODES 1 and 2, requirements for operation of the Reactor Coolant Recirculation System are necessary since there is considerable energy in the reactor core and the limiting design basis tiansients and accidents are assumed to occur.

In MODES 3, 4, and 5, the consequences of an accident are reduced and the coastdown characteristics of the recirculation loops are not important.

ACTIONS A.1 When operating in Region I of the Power Flow map specified:in the I COLR or with no recirculation loops operating in MODE 1, the potential for thermal-hydraulic oscillations is greatly increasedand-sifficient margin may not be available for operator response to suppress potential thermal-hydraulic oscillations. Therefore, the reactor mode switch must be immediately placed in the shutdown position. Action is taken immediately to place the plant in a condition where any potential.for thermal-hydraulic instabilities will be terminated. The requirements are consistent to those of References 4

.and 5.

(continued)

SUSQUEHANNA - UNIT 2 TS / B3.4-5 Revision 2

I ,- ..., ! ; 1 :. --. 1 PPL Rev. I Recirculation Loops Operating B 3.4.1 BASES ACTIONS B.1 (continued)

When operating in Region II of the Power / Flow map specified in the COLR with indications that thermal hydraulic oscillations are occurring as defined in the ACTION, or when less than 50% of the required LPRM I

upscale alarms are OPERABLE the potential for thermal-hydraulic oscillations is greatly increased and sufficient margin may not be available for operator response to suppress potential thermal-hydraulic oscillations.

The number and location of LPRM strings in each zone assure that with 50% or more of the associated LPRM upscale alarms OPERABLE sufficient monitoring capability is available to detect core wide and regional oscillations.

LPRM upscale alarms are required to detect reactor core thermal-hydraulic instability events. The criteria for determining which LPRM upscale alarms are required is based on assignment of these alarms to designated core zones. These core zones consist of the level A, B, and C alarms in 4 or 5. adjacent LPRM strings. The number and location of LPRM strings in each zone assure that with 50% or more of the associated LPRM upscale alarms OPERABLE sufficient monitoring capability is available to detect core wide and regional oscillations.

Operating plant instability data is used to determine the specific LPRM strings assigned to each zone.

The ACTION to place the reactor mode switch in shutdown immediately is necessary since the probability of thermal-hydrauc oscillations is greatly increased if in CONDITION B. Without the monitoring capability, control rods must be inserted to terminate any potential for undetected thermal-hydraulic instabilities.

C.1 When operating in Region II of the Power/ Flow map specified in the COLR, the potential for thermal-hydraulic oscillations is increased and sufficient margin may not be available for operator response to suppress I

potential thermal-hydraulic oscillations. Therefore, action must be initiated

• immediately to restore operation outside of Regions II of the Power / Flow map specified in the COLR. This can be accomplished by either decreasing THERMAL POWER with control rod insertion or increasing core flow by increasing recirculation pump speed. The starting of a recirculation (continued)

SUSQUEHANNA - UNIT 2 TS B 3.4-6 Revision 2

PPL Rev. 1 Recirculation Loops Operating B 3.4.1 BASES ACTIONS CA (continued) pump will not be used as a means to enter the required Regions because the starting of a recirculation pump with the plant operating above the 80% rod line is prohibited due to potential instability problems.

D.1 Recirculation loop flow must match within required limits when both recirculation loops are in operation. If flow mismatch is not within required limits, matched flow must be restored within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />. If matched flows are not restored, the recirculation loop with lower flow must be declared "not in operation." Should a LOCA occur with recirculation loop flow not matched, the core flow coastdown and resultant core response may not be bounded by the LOCA analyses. Therefore, only a limited time is allowed prior to imposing restrictions associated with'single loop operation. Operation with only one recirculation loop satisfies the requirements of the LCO and the initial conditions of the accident sequence.

The 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> Completion Time is based on the low probability of an accident occurring during this time period, providing a reasonable time to complete the Required Action, and considering that frequent core monitoring by operators allows abrupt changes in core flow conditions to be quickly detected..

These Required Actions do not require tripping the recirculation pump in the lowest flow loop when the mismatch between total jet pump flows of the two loops is greater than the required limits. However, in cases where large flow mismatches occur, low flow or reverse flow can occur in the low flow loop jet pumps, causing vibration of the jet pumps. If zero or reverse flow is detected, the condition should be alleviated by changing recirculation pump speed to re-establish forward flow or by tripping the pump.

E.1 With no recirculation loops in operation while in MODE 2 or if after going to single loop operations the required limits and setpoints cannot be (continued)

SUSQUEHANNA - UNIT 2 TS /B 3.4-7 Revision 2

PPL Rev. I Recirculation Loops Operating B 3.4.1 BASES .

ACTIONS E.1 (continued) established, the plant must be brought to MODE 3, where the LCO does not apply within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. In this condition, the recirculation loops are not required to be operating because of the reduced severity of DBAs and minimal dependence on the recirculation loop coastdown characteristics.

The allowed Completion Time of 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> is reasonable to reach MODE 3 from full power conditions in an orderly manner without challenging plant systems.

SURVEILLANCE REQUIREMENTS .4.1.1 This SR ensures the recirculation loops are within the allowable limits for mismatch. At low core flow (i.e., < 75 million Ibm/hr), the MCPR requirements provide larger margins to the fuel cladding integrity Safety Limit such that the potential adverse effect of early boiling transition during a LOCA is reduced. A larger flow mismatch can therefore be allowed when core flow is < 75 million Ibm/hr. The recirculation loop jet pump flow, as used in this Surveillance, is the summation of the flows from all of the jet pumps associated with a single recirculation loop.

The mismatch is measured in terms of core flow. If the flow mismatch exceeds the specified limits, the loop with the lower flow is considered inoperable. The SR is not required when both loops are not in operation since the mismatch limits are meaningless during single-loop or natural circulation operation. The Surveillance must be performed within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> after both loops are in operation. The 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> Frequency is consistent with the Surveillance Frequency for jet pump OPERABILITY verification and has been shown by operating experience to be adequate to detect off normal jet pump loop flows in a timely manner.

SR 3.4.1.2 This SR ensures the combination of core flow and THERMAL POWER are within required limits to prevent uncontrolled thermal hydraulic oscillations by ensuring the recirculation loops are within the limits established by the Power I Flow map specified in the COLR. At low recirculation flows and I high reactor power, the reactor (continued)

SUSQUEHANNA - UNIT 2 T S / B 3.4-8 Revision 2

.;-<; i. 7 i PPL Rev. 1 Recirculation Loops Operating B 3.4.1 BASES SURVEILLANCE REQ~UIREMAENTS SR 3.4.1.2 (continued) exhibits increased susceptibility to thermal-hydraulic instability.

The Power / Flow map. specified in the COLR is based on guidance provided in References 3, 4, and 5 which also provided the guidance on how to respond to operation in these conditions: The 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> Frequency is based on operating experience and the operators inherent knowledge

-of the current reactor status, including significant changes in THERMAL POWER and core flow to ensure the requirements are constantly met.

SR 3.4.1.3 As noted, this SR is only applicable when in single loop operation. This SR ensures the recirculation pump limit is maintained. The 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> Frequency is based on operating experience and the operators- inherent knowledge of the current reactor status.

REFERENCES 1. FSAR, Section 6.3.3.7..

2. FSAR, Section 5.41.4.

.3. GE Service Information Letter No. 380, "BWR Core thermal Hydraulic Stability," Revision 1, February 10, 1984.

4. Letter, L-. A. England to M. J. Virgilio, UBWR Owner's Group Guidelines l for Stability Interim Corrective Action," June 6, 1994.

5. EMF-CC-074 (P)(A), Volume 4, Revision 0, BWR Stability Analysis:

Assessment of STAIF with Input from MICROBURN-B2,"

November 1999.

6. Final Policy Statement on Technical Specifications Improvements, July 22,1993 (58 FR 39132).

SUSQUEHANNA - UNIT 2 TS / B3.4-9 Revision 2