ML20236G692

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Proposed Tech Specs,Revising TS 3.4.2 & TS 3.4.12 Re Reactor Coolant Sys Safety Valves & Low Temp Overpressure Protection
ML20236G692
Person / Time
Site: Arkansas Nuclear Entergy icon.png
Issue date: 06/29/1998
From:
ENTERGY OPERATIONS, INC.
To:
Shared Package
ML20236G680 List:
References
NUDOCS 9807060341
Download: ML20236G692 (15)
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Text

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4 PROPOSED TECHNICAL SPECIFICATION CHANGES 9807060041 980629 PDR ADOCK 05000368 -

P PDR S

4 INDEX LIMITING CONDITIONS FOR' OPERATION AND SURVEILLANCE REQUIREMENTS SECk' ION PAGE 3/4.3.3 (Continued)

Radioactive Liquid Effluent Monitoring Instrumentation....................................... 3/4 3-54 3/4.3.4 TURBINE OVERSPEED PROTECTION............................ 3/4 3-58 3/4.4 REACTOR COOLANT SYSTEM

-3/4.4.1 REACTOR COOLANT LOOPS AND COOLANT CIRCULATION........... 3/4 4-1 3/4.4.2. SAFETY VALVES - SHUTDOWN................................ 3/4 4-3 3/4.4.3 SAFETY VALVES - OPERATING............................... 3/4 4-4 3/4.4.4 PRESSURI"ER............................................. 3/4 4-5 3/4.4.5 STEAM GENERATORS........................................ 3/4 4-6 3/4.4.6 REACTOR COOLANT SYSTEM LEAKAGE i

Leakage Detection Systems............................... 3/4 4-13 Reactor Coolant System Leakage.......................... 3/4 4-14 3/4.4.~1 ~ ' CHEMISTRY............................................... 3/4 4-15 3/4.4.8 SPECIFIC ACTIVITY....................................... 3/4 4-18 3/4.4.9 PRESSURE / TEMPERATURE LIMITS Reactor Coolant System.................................. 3/4 4-22 Pressurizer............................................. 3/4 4-25 3/4.4.10 STRUCTURAL INTEGRITY

ASME Code Class 1, 2 and 3 Components................... 3/4 4-26 3/4.4.11 REACTOR COOLANT SYSTEM VENTS............................ 3/4 4-27 3/4.4.12 LOW TEMPERATURE OVERPRESSURE PROTECTION (LTOP) SYSTEM... 3/4 4-28 l 3/4.5 EMERGENCY CORE COOLING SYSTEMS (ECCS) 3/4.5.1 SAFETY INJECTION TANKS.................................. 3/4 5-1 ARKANSAS - UNIT 2 VI Amendment No. 49,M ,G ,  !

E______ _ _ _ _ _ _ _ _ _ _ _ _ _ . _ _ _ _ _ _ __ _ - . _ . - - - - - - - - _ . - - - _ . - - - - - - - - - - - - -

, INDEX BASES 4

SECTION PAGE 3/4.4 REACTOR COOLANT SYSTEM 3/4.4.1 REACTOR COOLANT LOOPS AND COOLANT CIRCULATION........... B 3/4 4-1 3/4.4.2 and 3/4.4.3 SAFETY VALVES................................. B 3/4 4-1 3/4.4.4 PRESSURIZER............................................. B 3/4 4-2 3/4.4.5 STEAM GENERATORS........................................ B 3/4 4-2 3/4.4.6 REACTOR COOLANT SYSTEM LEAKAGE.......................... B 3/4 4-3 3/4.4.7 CHEMISTRY............................................... B 3/4 4-4 3/4.4.8 SPECIFIC ACTIVITY....................................... B 3/4 4-4 3/4.4.9 PRESSURE / TEMPERATURE LIMITS............................. B 3/4 4-5 3/4.4.10 STRUCTURAL INTEGRITY.................................... B 3/4 4-11 3/4.4.11 REACTOR COOLANT SYSTEM VENTS............................ B 3/4 4-11 3/4.4.12 LOW TEMPERATURE OVERPRESSURE PROTECTION SYSTEM.......... B 3/4 4-12 l l 3/4.5_ EMERGENCY CORE COOLING SYSTEMS (ECCS) 3/4.5.1 SAFETY INJECTION TANKS.................................. B 3/4 5-1 j 1

3/4.5.2 and 3/4.5.3 ECCS SUBSYSTEMS.............................. B 3/4 5-1 3/4.5.4 REFUEIING WATER TANK (RWT).............................. B 3/4 5-2 3/4.6 CONTAINMENT SYSTEMS 3/4.6.1 PRIMARY CONTAINMENT..................................... B 3/4 6-1 3/4.6.2 DEPRESSURIZATION AND COOLING SYSTEMS.................... B 3/4 6-3 3/4.6.3 CONTAINMENT ISOLATION VALVES............................ B 3/4 6-4 3/4.6.4 COMBUSTIBLE GAS CONTROL................................. B 3/4 6-4 1

ARKANSAS - UNIT 2 XII Amendment No. 49,60,63,

. REACTOR COOLANT SYSTEM e

SAFETY VALVES - SHUTDOWN LIMITING CONDITION FOR OPERATION 3.4.2 A minimum of one pressurizer code safety valve shall be OPERABLE j with a lift setting of 2500 PSIA +1,-3%*.

l APPLICABILITY: MODE 4 with Tc > 220'F. l ACTION:

With no pressurizer code safety valve OPERABLE, reduce Tc to 5 220*F within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.

SURVEILLANCE REQUIREMENTS 4.4.2 No additional Surveillance Requirements other than those required by Specification 4. 0.5.

  • The lift setting pressure shall correspond to ambient conditions of the valve at nominal operating temperature and pressure. If found outside of a i 1% tolerance band, the setting shall be adjusted to within i 1% of the lift setting shown.

I ARKANSAS - UNIT 2 3/4 4-3 Amendment No. 449,144,

". REACTOR COOLANT SYSTEM LOW TEMPERATURE OVERPRESSURE PROTECTION (LTOP) SYSTEM l LIMITING CONDITION FOR OPERATION 3.4.12 The LTOP system shall be OPERABLE with each SIT isolated that is pressurized to 2 300 psig, ands

a. Two LTOP relief valves with a lif t setting of 5 430 psig, or
b. The Reactor Coolant System depressurized with an RCS vent path 2 6.38 square inches.

I APPLICABILITY: MODE 4 with Tc s 220*F, MODE 5, MODE 6 with reactor vessel head in place.

ACTION:

a. With one LTOP relief valve inoperable in MODE 4,. restore the inoperable valve to OPER'SLE status within 7 days or depressurize and vent the RCS through a 2 6.38 square inch vent path within the next 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />.
b. With one LTOP relief valve inoperable in MODE 5 or 6, restore the inoperable relief valve to OPERABLE status within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or depressurize and vent the RCS through a 2 6.38 square inch vent path within the next 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />.
c. With both LTOP relief valves inoperable, depressurize and vent the RCS through a 2 6.38 square inch vent path within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />.
d. With a SIT not isolated and pressurized to 2 300 psig, isolate the affected SIT within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />. If the affected SIT is not isolated within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />, either:

(1) Depressurize the SIT to.< 300 psig within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />, or l (2) Increase cold leg temperature to > 220'F within the next 12 l hours.

e. The provisions of Specification 3.0.4 are not applicable.

l ARKANSAS - UNIT 2 3/4 4-28 Amendment No. MO, i

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. . . _ _.______.__________J

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, e 3/4.4 REACTOR COOLANT SYSTEM l t

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BASES I 3/4.4.1 REACTOR COOLANT LOOPS AND COOLANT CIRCULATION l

The plant is designed to operate with both reactor coolant loops and l associated reactor coolant pumps in operation, and maintain DNBR above the limits specified by Specification 3.2.4 during all norum1 operations and anticipated transients.

In MODE 3, a single reactor coolant loop provides sufficient heat removal capability for removing decay heats however, single failure l considerations require that two loops be OPERABLE.

In MODES 4 and 5, a single reactor coolant loop or shutdown cooling loop provides sufficient heat removal capability for removing decay heat; but single failure considerations require that at least two loops be OPERABLE. Thus, if the reactor coolant loops are not OPERABLE, this specification requires two shutdown cooling loops to be OPERABLE.

The operation of one Reactor Coolant Pump or one shutdown cooling pump provides adequate flow to ensure mixing, prevent stratification and I produce gradual reactivity changes during boron concentration reductions in the Reactor Coolant System. The reactivity change rate associated with boron reductions will, therefore, be within the capability of operator recognition and control.

3/4.4.2 and 3/4.4.3 SAFETY VALVES The pressurizer code safety valves operate to prevent the RCS from being pressurized above its safety Limit of 2750 psia. Each safety valve is designed to relieve 420,000 lbs. per hour of saturated steam at the valve setpoint. The relief capacity of a single safety valve is adequate to relieve any overpressure condition which could occur during shutdown.

Two safety valves are required in MODES 1, 2 and 3. One safety valve is required in MODE 4 with Te > 220'F. For the remainder of MODES 4, 5 and 6 with the reactor vessel head in place, overpressure protection is provided by the operating procedures and LCO 3.4.12, " Low Temperature overpressure Protection (LTOP) System".

During operation, all pressurizer code safety valves must be OPERABLE to prevent the RCS from being pressurized above its safety limit of 2750 psia. The combined relief capacity of these valves is sufficient to limit the Reactor Coolant System pressure to within its Safety Limit of 2750 psia following a complete loss of turbine generator load while operating at RATED THERMAL POWER and assuming no reactor trip until the first Reactor Protective System trip setpoint (Pressurizer Pressure-High) is reached (i.e., no credit is taken for a direct reactor trip on the loss of turbine) and also assuming no operation of the steam dump valves.

ARKANSAS - UNIT 2 B 3/4 4-1 Amendment No. 34,G9,4-49,

____________A

, REACTOR COOLAUT SYST @

BASES ,

3/4.4.12 LOW TEMPERATURE OVERPRESSURE PROTECTION SYSTEM l l Low temperature overpressure protection (LTOP) of the RCS, including I the reactor vessel, is provided by redundant relief valves on the pressurizer which discharge from a single discharge header. Each LTOP relief valve is a direct action, spring-loaded relief valve, with orifice 2

area of 6.38 in and a lif t setting of s 430 psig, and is capable of ndtigating the worst-case design basis pressurization event. The LTOP design basis event is a simultaneous injection of two HPSI pumps and all l three charging pumps to the water-solid RCS. The analyses assume that the safety injection tanks (SITS) are either isolated or depressurized such that they are unable challenge the LTOP relief setpoints.

Since neither the LTOP reliefs nor the RCS vent is analyzed for the pressure transient produced from SIT injection, the LCO requires each SIT that is pressurized to 2 300 psig to be isolated. The isolated SITS must have their discharge valves closed and the associated MOV power supply breaker in the open position. The individual SITS may be unisolated when pressurized to < 300 psig. The associated instrumentation uncertainty is not included in the 300 psig value and therefore, the procedural value for unisolating the SITS with the LTOPs in service will be reduced.

The LTOP system, in combination with the RCS heatup and cooldown limitations of LCO 3.4.9.1 and administrative restrictions on RCP operation, provides assurance that the reactor vessel non-ductile fracture l l

limits are not exceeded during the design basis event at low RCS temperatures. These non-ductile fracture limits are identified as LTOP pressure-temperature (P-T) limits, which were specifically developed to provide a basis for the LTOP system. These LTOP P-T limits, along with the  ;

LTOP enable temperature, were developed using guidance provided in ASME Code Section XI, Division 1, Code Case N-514 that mandates that "LTOP systems shall limit the maximum pressure in the vessel to 110% of the pressure determined to satisfy Appendix G, paragraph G-2215 of Section XI, l Division 1". I The enable temperature of the LTOP isolation valves is based on any RCS cold leg temperature reaching 220*F (including a 20'F uncertainty) .

Although each relief valve is capable of ndtigating the design basis LTOP event, both LTOP relief valves are required to be OPERABLE below the enable l temperature to meet the single failure criterion of NRC Branch Technical Position RSB 5-2, unless any RCS vent path of 6.38 in* (equivalent relief valve orifice area) or larger is maintained.

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ARKANSAS - UNIT 2 B 3/4 4-12 Amendment No. -140,

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I 4 MW OF CURRENT ANO-2 TECHNICAL SPECIFICATIONS (FORINFO ONLY)

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i INDEX 1

l LIMITING CONDITIONS FOR OPERATION AND SURVEILLANCE REQUIREMENTS SECTION PAGE l 3/4.3.3 (Continued)

Radioactive Liquid Effluent Monitoring Instrumentation....................................... 3/4 3 '54 3/4.3.4 TURBINE OVERSPEED PROTECTION............................ 3/4 3-58 3/4.4 REACTOR COOLANT SYSTEM 3/4.4.1 REACTOR COOLANT LOOPS AND COOLANT CIRCULATION........... 3/4 4-1 1 l

3/4.4.2 SAFETY VALVES - SHUTDOWN................................ 3/4 4-3 '

3/4.4.3 SAFETY VALVES - OPERATING............................... 3/4 4-4 3/4.4.4 PRESSURIZER............................................. 3/4 4-5 4

3/4.4.5 STEAM GENERATORS........................................ 3/4 4-6 3/4.4.6 REACTOR COOLANT SYSTEM LEAKAGE Leakage Detection Systems............................... 3/4 4-13 Reactor Coolant System Leakage.......................... 3/4 4-14 3/4.4.7 C H EMI S T RY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3/4 4-15 3/4.4.8 SPECIFIC. ACTIVITY....................................... 3/4 4-18 3/4.4.9 PRESSURE / TEMPERATURE LIMITS Reactor Coolant System.................................. 3/4 4-22 Pressurizer............................................. 3/4 4-25 3/4.4.10 STRUCTURAL INTEGRITY ASME Code Class 1, 2 and 3 Components................... 3/4 4-26 3/4.4.11 REACTOR COOLANT SYSTEM VENTS............................ 3/4 4-27 3/4.4.12 LOW TEMPERATURE OVERPRESSURE PROTECTION (LTOP) SYSTEM... 3/4 4-28 l

,3,/ 4 . 5 EMERGENCY CORE COOLING SYSTEMS (ECCS) '

3/4.5.1 SAFETY INJECTION TANKS.................................. 3/4 5-1 l

1 ARKANSAS - UNIT 2 VI Amendment No. M,M,G,

i e

  • INDEX BASES SECTION PAGE 3/4.4 REACTOR COOLANT SYSTEM 3/4.4.1 REACTOR COOLANT LOOPS AND COOLANT CIRCULATION........... B 3/4 4-1 l 3/4.4.2 and 3/4.4.3 SAFETY VALVES................................. B 3/4 4-1 l

l 3/4.4.4 PRESSURIZER............................................. B 3/4 4-2 3/4.4.5 STEAM GENERATORS........................................ B 3/4 4-2 l 3/4.4.6 REACTOR COOLANT SYSTEM LEAKAGE.......................... B 3/4 4-3 3/4.4.~1 CHEMISTRY............................................... B 3/4 4-4 3/4.4.8 SPECIFIC ACTIVITY....................................... B 3/4 4-4 3/4.4.9 PRESSURE / TEMPERATURE LIMITS............................. B 3/4 4-5 3/4.4.10 STRUCTURAL INTEGRITY.................................... B 3/4 4-11 3/4.4.11 REACTOR COOLANT SYSTEM VENTS............................ B 3/4 4-11 3/4.4.12 LOW TEMPERATURE OVERPRESSURE PROTECTION SYSTEM.......... B 3/4 4-12 l l

3/4.5 EMERGENCY CORE COOLING SYSTEMS (ECCS) l l

3/4.5.1 SAFETY INJECTION TANKS.................................. B 3/4 5-1 l 3/4.5.2 and 3/4.5.3 ECCS SUBSYSTEMS.............................. B 3/4 5-1 3/4.5.4 REFUELING WATER TANK (RWT).............................. B 3/4 5-2 3/4.6 CONTAINMENT SYSTEMS 3/4.6.1 PRIMARY CONTAINMENT..................................... B 3/4 6-1 3/4.6.2 DEPRESSURIZATION AND COOLING SYSTEMS.................... B 3/4 6-3 3/4.6.3 CONTAINMENT ISOLATION VALVES............................ B 3/4 6-4 3/4.6.4 COMBUSTIBLE GAS CONTROL................................. B 3/4 6-4 l

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! ARKANSAS - UNIT 2 XII Amendment No. M,M,6,

_ _ _ - . _ _ _ . _ _ _ _. . _ _ _ _ _ - _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ . ____ _ ___________________ ______-s

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SAFETY VALVES - SHUTDOWN j LIMITING CONDITION FOR OPERATION 3.4.2 A minimum of one pressurizer code safety valve shall be OPERABLE with a lift setting of 2500 PSIA +1,-3%*#. l APPLICABILITY: MODES 4 with Tc > 220*Fafwi-6. l ACTION:

With no pressurizer code safety valve OPERABLE, reduce Tc to s 220*F within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.i m dict:1y :::p;nd 11 :p:::ti::: inv:lving p::itiv: ::::tivity ch:nge:

nd pl::: :n Ori"_S LE chutd =. ::: ling 1 :p int: p;::ti:n. $

l SURVEILLANCE REQUIREMENTS i 4.4.2 No additional Surveillance Requirements other than those required by Specification 4.0.5.

  • The lift setting pressure shall correspond to ambient conditions of the valve at nominal operating temperature and pres: Pre. If found outside of l l a i 1% tolerance band, the setting shall be aQ uate.t to within i 1% of the l lift setting shown. i "Equiv:1:nt :: lief ::p::ity during ".005 5 ::ti fic: th: ::quir:2:nt: Of .

thi: Sp :ific: tion Thi: 211 v: h:th p :::uri::: ::d; ::fety valve: te b l

ved for testing 2nd/ : :intenance.

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t ARKANSAS - UNIT 2 3/4 4-3 Amendment No. M9,444, t

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, #*. REACTOR COOLANT SYSTEM

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LOW TEMMRATURE OVERPRESSURE PROTECTION (LTOP) SYSTEM l LIMITING CONDITION FOR OPERATION 3.4.12 Ibt_i : t r.;+:::t u r: :v::p::::::: pr:t::ti:n (LTOPt gystem shall l be OPERABLE with each SIT isolated _that is pressurized to h_3_0_Q ps g , and:

a. Two LTOP relief valves with a lift setting of s 430 psig, or
b. The Reactor Coolant System depresuurized with an RCS vent path 2 6.38 square inchesar S!T i:01 ti:n i: :nly ::quir:d when SIT pe ::ur; i: g:::ter een :: equ:1 t: RCS p :::ure,-

i l . APPLICABILITY: MODE 4 with Te s 220*F, MODE 5, MODE 6 with reactor vessel head in place.

ACTION:

a. With one LTOP relief valve inoperable in MODE 4, restore the inoperable valve to OPERABLE status within 7 days or i

depressurize and vent the RCS through a 2 6.38 square inch vent path within the next 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />.

b. With one LTOP relief valve inoperable in MODE 5 or 6, eith: (1) l restore the inoperable relief valve to OPERABLE status within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> r or (2)  ;;plet: depressurizeeMen and venting of the RCS through a 2 6.38 square inch vent path within the_next 8: t:t:1 ef-4G hours,
c. With both LTOP relief valves inoperable, depressurize and vent the RCS through a 2 6.38 square inch vent path within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />. I
d. With a SIT not isolated and pressurized to 2 300 psig, isolate the affected SIT within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />. If the affected SIT is not isolated within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> quired :: tion i: n:t :=t, either:

(1) Depressurize the SIT to y 300 osiale:: th:n the nOS p ::::::

within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />, or (2) Increase cold leg temperature to gg
:ter th = :: qu:1 te 220'F within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.
e. The provisions of Specification 3.0.4 are not applicable.

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ARKANSAS - UNIT 2 3/4 4-28 Amendment No. MG,

, /*. 3/4.4 REACTOR COOLANT SYSTEM

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BASES 3/4.4.1 REACTOR COOLANT LOOPS AND COOLANT CIRCULATION The plant is designed to operate with both reactor coolant loops and associated reactor coolant pumps in operation, and maintain DNBR above the limits specified by Specification 3.2.4 during all normal operations and anticipated transients.

In MODE 3, a single reactor coolant loop provides sufficient heat removal capability for removing decay heats however, single failure considerations require that two loops be OPERABLE.

In MODES 4 and 5, a single reactor coolant loop or shutdown cooling loop provides sufficient heat removal capability for removing decay heat; but single failure considerations require that at least two loops be OPERABLE. Thus, if the reactor coolant loops are not OPERABLE, this specification requires two shutdown cooling loops to be OPERABLE.

The operation of one Reactor Coolant Pump or one shutdown cooling pump provides adequate flow to ensure mixing, prevent stratification and produce gradual reactivity changes during boron concentration reductions in the Reactor Coolant System. The reactivity change rate associated with boron reductions will, therefore, be within the capability of operator recognition and control.

3/4.4.2 and 3/4.4.3 SAFETY VALVES The pressurizer code safety valves operate to prevent the RCS from being pressur red above its Safety Limit of 2750 psia. Each safety valve is designed to Aalieve 420,000 lbs. per hour of saturated steam at the valve setpoint. The relief capacity of a single safety valve is adequate to relieve any overpressure condition which could occur during shutdown.

In th: ev:nt that n :sfety valv : ::: O P En.'.3 LE, an perating chutdown c;; ling 100p, : nnt ted to th CCC, provid:: Overprce:ure relief pability :nd will prevent nCS cverpressurirati n.

Two safety valves are reauired in MODES 1, 2 and 3. One safety valve is reauired in MODE 4 with T, > 220*F. For the remainder of MODES 4, 5 and 6 with the reactor vessel head in place, overpressure protection is provided by the operating procedures and LCO 3.4.12, " Low Temperature Overpressure Protection (LTOP) System".

During operation, all pressurizer code safety valves must be OPERABLE to prevent the RCS from being pressurized above its safety limit of 2750 psia. The combined relief capacity of these valves is sufficient to limit the Reactor Coolant System pressure to within its safety Limit of 2750 psia following a complete loss of turbine generator load while operating at RATED THERMAL POWER and assuming no reactor trip until the first Reactor Protective System trip setpoint (Pressurizer Pressure-High) is reached (i.e., no credit is taken for a direct reactor trip on the loss of turbine) and also assuming no operation of the steam dump valves.

ARKANSAS - UNIT 2 B 3/4 4-1 Amendment No. G4,G9,-149,

'3 p*

REACTOR COOLANT SYSTEM 8ASES l

, 3/4.4.12 LOW TEMPERATt"AE OVERPRESSURE PROTECTION SYSTEMG l Low temperature overpressure protection (LTOP) of the RCS, including  !

the reactor vessel, is provided by redundant relief valves on the pressurizer which discharge from a single discharge header. Each LTOP relief valve is a direct action, spring-loaded relief valve, with orifice l' area of 6.38 in and a lift setting of 5 430 psig, and is capable of mitigating the worst-case design basis pressurization event. The LTOP design basis event is a simultaneous injection of two HPSI pumps and all three charging pumps to the water-solid RCS. The analyses assume that the i safety injection tanks ISITs) are either isolated or eee-depressurized,gggh j that they are unable challence the LTOP relief setooints.

Since neither the LTOP reliefs nor the RCS vent is analyzed for the pressure transient produced from SIT iniection, the LCO requires each SIT j that is pressurized to 2 300 osia to be isolated. The isolated SITS must I have their discharoe valves closed and the associated MOV oower supply breaker in the open position. The individual SITS may be unLsolated when pressurized to < 300 osio. The associated instrumentation uncertainty is not included in the 300 osia value and therefore, the procedural value for ,

unisolatina the SITS with the LTOPs in service will be reduced.

The LTOP system, in combination with the RCS heatup and cooldown l limitations of LCO 3.4.9.1 and administrative restrictions on RCP operation, provides assurance that the reactor vessel non-ductile fracture limits are not exceeded during the design basis event at low RCS  !

temperatures. These non-ductile fracture lindts are identified as LTOP l pressure-temperature (P-T) limits, which were specifically developed to provide a basis for the LTOP system. These LTOP P-T limits, along with the LTOP :nable temperature, were developed using guidance provided in ASME Code Section XI, Division 1, Code Case N-514 that mandates that "LTOP systems shall limit the maximum pressure in the vessel to 110% of the l pressures determined to satisfy Appendix G, paragraph G-2215 of Section XI, Divisj on 1".

The enable temperature of the LTOP isolation valves is based on any I RCS cold leg temperature reaching 220'F (including a 20*F uncertainty) .

Although each relief valve is capable of mitigating the design basis LTOP event, both LTOP relief valves are required to be OPERABLE pened below the l l enable temperature to meet the single failure criterion of NRC Branch Technical Position RSB 5-2, unless any RCS vent path of 6.38 in* (equivalent relief valve orifice area) or larger is maintained.

ARKANSAS - UNIT 2 B 3/4 4-12 Amendment No. -14G,

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