ML043170036

TS for Sequoyah, Unit 1, Emergency Amendment, Enclosure, Extend Implementation Period

ML043170036
Person / Time
Site:	Sequoyah
Issue date:	11/09/2004
From:	NRC/NRR/DLPM
To:
pascarelli, R J, NRR/DLPM, 415-1245
References
TAC MC5041
Download: ML043170036 (33)

Text

INDEX DEFINITIONS SECTION 1.0 DEFINITIONS 1.1 ACTION ............................................ 1-1 1.2 AXIAL FLUX DIFFERENCE ............................................ 1-1 1.3 BYPASS LEAKAGE PATH ............................................ 1-1 1.4 CHANNEL CALIBRATION ............................................ 1-1 1.5 CHANNEL CHECK ............................................ 1-1 1.6 CHANNEL FUNCTIONAL TEST ............................................ 1-2 1.7 CONTAINMENT INTEGRITY ............................................ 1-2 1.8 CONTROLLED LEAKAGE (Deleted) ............................................ 1-2 1.9 CORE ALTERATION ............................................ 1-2 1.10 CORE OPERATING LIMITS REPORT ............................................ 1-2 1.11 DOSE EQUIVALENT 1-131 ............................................ . 1-3 1.12 E-AVERAGE DISINTEGRATION ENERGY ............................................. 1-3 1.13 ENGINEERED SAFETY FEATURE RESPONSE TIME ........................................ 1-3 1.14 FREQUENCY NOTATION ............................................ . 1-3 1.15 GASEOUS RADWASTE TREATMENT SYSTEM ............................................ 1-3 1.16 IDENTIFIED LEAKAGE ............................................ . 1-3 1.17 MEMBERS OF THE PUBLIC (Deleted) ............................................ 1-4 1.18 OFFSITE DOSE CALCULATION MANUAL ............................................. 1-4 1.19 OPERABLE - OPERABILITY ............................................. 1-4 1.20 OPERATIONAL MODE - MODE ............................................ 1-4 1.21 PHYSICS TESTS ............................................ . 1-4 1.22 PRESSURE BOUNDARY LEAKAGE ............................................. 1-5 1.23 PRESSURE AND TEMPERATURE LIMITS REPORT (PTLR) .................................. 1-5 1.24 PROCESS CONTROL PROGRAM ............................................. 1-5 SEQUOYAH - UNIT 1 1 Amendment No. 71, 155, 259, 281. 2 9 4 297 1

INDEX DEFINITIONS SECTION 1.0 DEFINITIONS (Continued) 1.25 PURGE - PURGING .................................... 1-5 1.26 QUADRANT POWER TILT RATIO .................................... 1-5 1.27 RATED THERMAL POWER .................................... 1-5 1.28 REACTOR TRIP SYSTEM RESPONSE TIME .................................... 1-5 1.29 REPORTABLE EVENT .................................... 1-5 1.30 SHIELD BUILDING INTEGRITY .................................... 1-6 1.31 SHUTDOWN MARGIN .................................... 1-6 1.32 SITE BOUNDARY .................................... 1-6 1.33 SOLIDIFICATION .................................... 1-6 1.34 SOURCE CHECK .................................... 1-6 1.35 STAGGERED TEST BASIS .................................... 1-6 1.36 THERMAL POWER .................................... 1-6 1.37 UNIDENTIFIED LEAKAGE .................................... 1-7 1.38 UNRESTRICTED AREA .................................... 1-7 1.39 VENTILATION EXHAUST TREATMENT SYSTEM .................................... 1-7 1.40 VENTING .................................... 1-7 OPERATIONAL MODES (TABLE 1.1) .. 1-8 FREQUENCY NOTATION (TABLE 1.2) .. -9 SEQUOYAH - UNIT 1 11 Amendment No. 71,155, 294, 297 1

INDEX LIMITING CONDITIONS FOR OPERATION AND SURVEILLANCE REQUIREMENTS SECTION PAGE 3/4.4 REACTOR COOLANT SYSTEM 3/4.4.1 REACTOR COOLANT LOOPS AND COOLANT CIRCULATION Startup And Power Operation ........................................................ 314 4-1 Hot Standby ....................................................... 3/44-1 a Shutdown ....................................................... 3/4 4-2 3/4.4.2 SAFETY VALVES - SHUTDOWN ........................................................ 3/4 4-3 3/4.4.3 SAFETY AND RELIEF VALVES - OPERATING Safety Valves - Operating ....................................................... 3/4 4-4 Relief Valves - Operating ....................................................... 3/4 4-4a 3/4.4.4 PRESSURIZER ....................................................... 3/4 4-5 3/4.4.5 STEAM GENERATORS ....................................................... 3/4 4-6 3/4.4.6 REACTOR COOLANT SYSTEM LEAKAGE Leakage Detection Instrumentation ....................................................... 3/4 4-13 Operational Leakage....................................................... 3/4 4-14 Reactor Coolant System Pressure Isolation Valve Leakage ............................................... 3/4 4-15 3/4.4.7 CHEMISTRY ....................................................... 3/4 4-16 3/4.4.8 SPECIFIC ACTIVITY ....................................................... 3/4 4-19 3/4.4.9 RCS PRESSURE AND TEMPERATURE (P/T) LIMITS Reactor Coolant System ......................................................... 3/4 4-23 Pressurizer (Deleted) ....................................................... 3/4 4-26 3/4.4.10 DELETED ....................................................... 3/4 4-27 3/4.4.11 REACTOR COOLANT SYSTEM HEAD VENTS ....................................................... 3/4 4-28 3/4.4.12 LOW TEMPERATURE OVERPRESSURE PROTECTION (LTOP) SYSTEM .................... 3/4 4-29 SEQUOYAH - UNIT 1 VI Amendment No. 116, 133, 157, 208, 259, 9 4, 2 97

INDEX BASES SECTION PAGE 3/4.4.6 REACTOR COOLANT SYSTEM LEAKAGE ........................................................ B 3/4 4-4b 3/4.4.7 CHEMISTRY ......................................................... B 3/44-4r 3/4.4.8 SPECIFIC ACTIVITY .......................................................... B 3/44-5 3/4.4.9 RCS PRESSURE AND TEMPERATURE (P/T) LIMITS ................................................... B 314 4-6 3/4.4.10 STRUCTURAL INTEGRITY (DELETED) ........................................................ B 3/4 4-13 3/4.4.11 REACTOR COOLANT SYSTEM HEAD VENTS ........................................................ B 3/4 4-13 3/4.4.12 LOW TEMPERATURE OVERPRESSURE PROTECTION (LTOP) SYSTEM ...............B 3/4 4-14 314.5 EMERGENCY CORE COOLING SYSTEMS 314.5.1 ACCUMULATORS ........................................................ B 3/4 5-1 314.5.2 and 3/4.5.3 ECCS SUBSYSTEMS ........................................................ B 3/4 5-1 3/4.5.4 BORON INJECTION SYSTEM (DELETED) ......................................................... B 3/4 5-2 3/4.5.5 REFUELING WATER STORAGE TANK .......................................................... B 3/4 5-3 3/4.5.6 SEAL INJECTION FLOW ........................................................ B 3/4 5-4 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 6-3 3/4.6.4 COMBUSTIBLE GAS CONTROL ........................................................ B 3/4 6-4 3/4.6.5 ICE CONDENSER ......................................................... B 3/4 6-4 3/4.6.6 VACUUM RELIEF LINES ........................................................ B 3/4 6-6 3/4.7 PLANT SYSTEMS 3/4.7.1 TURBINE CYCLE ..... B 3/4 7-1 3/4.7.2 STEAM GENERATOR PRESSURE/TEMPERATURE LIMITATION ..... B 3/4 7-3 3/4.7.3 COMPONENT COOLING WATER SYSTEM ....... B 3/4 7-3a SEQUOYAH - UNIT 1 Xil Amendment No. 157, 197,259, 294, 297 l

PRESSURE BOUNDARY LEAKAGE 1.22 PRESSURE BOUNDARY LEAKAGE shall be leakage (except steam generator tube leakage) through a non-isolable fault in a Reactor Coolant System component body, pipe wall or vessel wall.

PRESSURE AND TEMPERATURE LIMITS REPORT (PTLR) 1.23 The PTLR is the unit specific document that provides the reactor vessel pressure and temperature limits, including heatup and cooldown rates and the LTOP arming temperature, for the current reactor vessel fluence period. These pressure and temperature limits shall be determined for each fluence period in accordance with Specification 6.9.1.15.

PROCESS CONTROL PROGRAM (PCP) 1.24 DELETED I PURGE - PURGING 1.25 PURGE or PURGING is the controlled process of discharging air or gas from a confinement to I maintain temperature, pressure, humidity, concentration or other operating condition, in such a manner that replacement air or gas is required to purify the confinement.

QUADRANT POWER TILT RATIO 1.26 QUADRANT POWER TILT RATIO shall be the ratio of the maximum upper excore detector I calibrated output to the average of the upper excore detector calibrated outputs, or the ratio of the maximum lower excore detector calibrated output to the average of the lower excore detector calibrated outputs, whichever is greater.

RATED THERMAL POWER (RTP) 1.27 RATED THERMAL POWER (RTP) shall be a total reactor core heat transfer rate to the reactor I coolant of 3455 MWt.

REACTOR TRIP SYSTEM (RTS) RESPONSE TIME 1.28 The REACTOR TRIP SYSTEM RESPONSE TIME shall be the time interval from when the I monitored parameter exceeds its (RTS) trip setpoint at the channel sensor until loss of stationary gripper coil voltage. The response time may be measured by means of any series of sequential, overlapping, or total steps so that the entire'response time Is measured. In lieu of measurement, response time may be verified for selected components provided that the components and the methodology for verification have been previously reviewed and approved by NRC.

REPORTABLE EVENT 1.29 DELETED I SEQUOYAH - UNIT 1 1-5 Amendment No. 12, 71, 141,148, 155,201, 233,251, 276,2 9 4, 297 i

SHIELD BUILDING INTEGRITY 1.30 SHIELD BUILDING INTEGRITY shall exist when: I

a. The door in each access opening is closed except when the access opening is being used for normal transit entry and exit.

b. The emergency gas treatment system isOPERABLE.

c. The sealing mechanism associated with each penetration (e.g., welds, bellows or 0-rings) is OPERABLE.

SHUTDOWN MARGIN 1.31 SHUTDOWN MARGIN shall be the instantaneous amount of reactivity by which the reactor is I subcritical or would be subcritical from its present condition assuming all full length rod cluster assemblies (shutdown and control) are fully inserted except for the single rod cluster assembly of highest reactivity worth which is assumed to be fully withdrawn.

SITE BOUNDARY 1.32 The SITE BOUNDARY shall be that line beyond which the land Is not owned, leased, or otherwise I controlled by the licensee (see Figure 5.1-1).

SOLIDIFICATION 1.33 Deleted I SOURCE CHECK 1.34 Deleted I STAGGERED TEST BASIS 1.35 A STAGGERED TEST BASIS shall consist of: I

a. A test schedule for n systems, subsystems, trains or other designated components obtained by dividing the specified test Interval into n equal subintervals,

b. The testing of one system, subsystem, train or other designated component at the beginning of each subinterval.

THERMAL POWER 1.36 THERMAL POWER shall be the total reactor core heat transfer rate to the reactor coolant. I SEQUOYAH - UNIT 1 1-6 Amendment No. 12, 71, 48, 155,2 9 4, 297 1

UNIDENTIFIED LEAKAGE 1.37 UNIDENTIFIED LEAKAGE shall be all leakage (except react6r coolant pump seal water injection I or leakoff) that is not IDENTIFIED LEAKAGE.

UNRESTRICTED AREA 1.38 An UNRESTRICTED AREA shall be any area, at or beyond the site boundary to which access is I not controlled by the licensee for purposes of protection of individuals from exposure to radiation and radioactive materials or any area within the site boundary used for residential quarters or industrial, commerical, institutional, and/or recreational purposes.

VENTILATION EXHAUST TREATMENT SYSTEM 1.39 A VENTILATION EXHAUST TREATMENT SYSTEM is any system designed and installed to I reduce gaseous radioiodine or radioactive material in particulate form in effluents by passing ventilation or vent exhaust gases through charcoal adsorbers and/or HEPA filters for the purpose of removing lodines or particulates from the gaseous exhaust stream prior to the release to the environment (such a system is not considered to have any effect on noble gas effluents). Engineered Safety Feature (ESF) atmospheric cleanup systems are not considered to be VENTILATION EXHAUST TREATMENT SYSTEM components.

VENTING 1.40 VENTING Is the controlled process of discharging air or gas from a confinement to maintain I temperature, pressure, humidity, concentration or other operating condition, in such a manner that replacement air or gas is not provided or required during VENTING. Vent, used in system names, does not imply a VENTING process.

SEQUOYAH - UNIT 1 1-7 Amendment No. 12, 71, 155, 259, 294, 297 1

REACTOR COOLANT SYSTEM 3/4.4.9 RCS PRESSURE AND TEMPERATURE (P/T) LIMITS LIMITING CONDITION FOR OPERATION 3.4.9.1 RCS pressure, RCS temperature, and RCS heatup and cooldown rates shall be maintained within the limits specified in the PTLR.

APPLICABILITY: At all times.

ACTIONS:

a. With the requirements of the LCO not met in MODE 1, 2, 3, or 4, restore the parameter(s) to within limits in 30 minutes and determine RCS is acceptable* for continued operation within 72 hours3 days <br />0.429 weeks <br />0.0986 months <br />. With the required action above not met, be in MODE 3 within the next 6 hours0.25 days <br />0.0357 weeks <br />0.00822 months <br /> and in MODE 5, with RCS pressure < 500 psig, within the following 30 hours1.25 days <br />0.179 weeks <br />0.0411 months <br />.

b. With the requirements of the LCO not met any time other than MODE 1, 2, 3, or 4, immediately initiate action to restore parameter(s) to within limits and, prior to entering MODE 4, determine RCS is acceptable*

for continued operation.

SURVEILLANCE REQUIREMENTS 4.4.9.1.1 Verify** RCS pressure, RCS temperature, and RCS heatup and cooldown rates are within the limits specified in the PTLR every 30 minutes.

• The determination that the RCS is acceptable for continued operation must be completed for any entry into Action (a) or (b).

• • Only required to be performed during RCS heatup and cooldown operations and RCS inservice leak and hydrostatic testing.

SEQUOYAH - UNIT 1 3/4 4-23 Amendment Nos. 12, 87, 157,2 9 4, 297 1

FIGURE 3.4 DELETED I SEQUOYAH UNIT 1 REACTOR COOLANT SYSTEM HEATUP LIMINATIONS APPLICABLE UP TO 16 EFPY SEQUOYAH - UNIT 1 3/4 4-24 Amendment No. 158, 2 9 4, 2 9 7 l

FIGURE 3.4 DELETED I SEQUOYAH UNIT 1 REACTOR COOLANT SYSTEM COOLDOWN LIMITATIONS APPLICABLE UP TO 16 EFPY SEQUOYAH - UNIT 1 314 4-25 Amendment No. 158,294, 297 1

REACTOR COOLANT SYSTEM PRESSURIZER LIMITING CONDITION FOR OPERATION 3.4.9.2 DELETED.

SEQUOYAH - UNIT I 314 4-26 Amendment No.36,294,297 l

REACTOR COOLANT SYSTEM 3/4.4.12 LOW TEMPERATURE OVER PRESSURE PROTECTION (LTOP) SYSTEM LIMITING CONDITION FOR OPERATION 3.4.12* An LTOP System shall be OPERABLE with a maximum of one centrifugal charging pump capable of injecting into the Reactor Coolant System (RCS) and the accumulators isolated and one of the following pressure relief capabilities:

a. Two power operated relief valves (PORVs) with lift settings within the limits specified in the PTLR, or

b. The RCS depressurized and an RCS vent 2 3 square inches.

APPLICABILITY: MODE 4 when any RCS cold leg temperature is

• the LTOP arming temperature specified in the PTLR, MODE 5, MODE 6 when the reactor vessel head Is on.

ACTION:

a. Should any safety injection pump or more than one charging pump be found capable of injecting Into the RCS, immediately initiate action to verify a maximum of one centrifugal charging pump is capable of injecting into the RCS.

b. With an accumulator not isolated when the accumulator pressure is greater than or equal to the maximum RCS pressure for existing cold leg temperature allowed in the PTLR, Isolate the affected accumulator within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />, or either;

1. Increase RCS cold leg temperature to >the LTOP arming temperature specified in the PTLR within 12 hours0.5 days <br />0.0714 weeks <br />0.0164 months <br />, or 2 Depressurize the affected accumulator to less than the maximum RCS pressure for existing cold leg temperature allowed in the PTLR within 12 hours0.5 days <br />0.0714 weeks <br />0.0164 months <br />.

c. With one required PORV inoperable In MODE 4, restore the required PORV to OPERABLE status within 7 days.

D With one required PORV inoperable In MODE 5 or 6, restore the required PORV to OPERABLE status within 24 hours1 days <br />0.143 weeks <br />0.0329 months <br />.

• 1) Two charging pumps may be made capable of injecting into the RCS for s 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> for pump swap operations.

2) Accumulator may be unisolated when accumulator pressure is less than the maximum RCS pressure for the existing RCS cold leg temperature allowed by the P/T limit curves provided in the PTLR.

3) For the purpose of making the required safety injection pumps and charging pump Inoperable, the following time is permitted: up to 4 hours0.167 days <br />0.0238 weeks <br />0.00548 months <br /> after entering MODE 4 from MODE 3, or prior to decreasing temperature on any RCS loop to below 3250F, whichever occurs first.

SEQUOYAH - UNIT 1 3/4 4-29 Amendment No. 157, 213,294, 297 I

REACTOR COOLANT SYSTEM ACTION (Continued)

e. With two required PORVs inoperable, or the Actions (a), (b), (c), or (d) not met, or the LTOP System inoperable for any reason other than (a), (b), (c), or (d), depressurize the RCS and establish RCS vent of a 3.0 square inches within 12 hours0.5 days <br />0.0714 weeks <br />0.0164 months <br />.

f. The provisions of Specification 3.0.4 are not applicable SURVEILLANCE REQUIREMENTS 4.4.12.1 Each PORV shall be demonstrated OPERABLE by

a. Performance of a CHANNEL FUNCTIONAL TEST*, but excluding valve operationat least once per 31 days;

b. Performance of a CHANNEL CALIBRATION on each required PORV actuation channel at least once per 18 months; and

c. Verifying the PORV block valve is open for each required PORV at least once per 72 hours3 days <br />0.429 weeks <br />0.0986 months <br />.

4.4.12.2 Verify no safety injection pumps are capable of injecting into the RCS within 4 hours0.167 days <br />0.0238 weeks <br />0.00548 months <br /> after entering MODE 4 from MODE 3 prior to the temperature of one or more RCS cold legs decreasing below 3250F, and every 12 hours0.5 days <br />0.0714 weeks <br />0.0164 months <br /> thereafter.

4.4.12.3 Verify a maximum of one charging pump Is capable of injecting into the RCS within 4 hours0.167 days <br />0.0238 weeks <br />0.00548 months <br /> after entering MODE 4 from MODE 3 prior to the temperature of one or more RCS cold legs decreasing below 3250F, and every 12 hours0.5 days <br />0.0714 weeks <br />0.0164 months <br /> thereafter.

4.4.12.4 Verify each accumulator is isolated at least once per 12 hours0.5 days <br />0.0714 weeks <br />0.0164 months <br /> 4.4.12.5 VerifV required RCS vent 2 3.0 square Inches open at least:

a. Once every 12 hours0.5 days <br />0.0714 weeks <br />0.0164 months <br /> for unlocked open vent valve(s) and,

b. Once every 31 days for other vent path(s)

• Not required to be performed until 12 hours0.5 days <br />0.0714 weeks <br />0.0164 months <br /> after decreasing RCS cold leg temperatures to < the LTOP arming temperature in the PTLR.

1. Only required to be met when complying with LCO 3.4.12.b.

SEQUOYAH - UNIT 1 3/4 4-30 Amendment No. 157,213, 294, 2971

RCS Pressure and Temperature (PIT) Limits B 3/4.4.9 B 3/4.4 REACTOR COOLANT SYSTEM (RCS)

BASES B 3/4 4.9 Reactor Coolant System Pressure and Temoerature (P/T) Limits BACKGROUND All components of the RCS are designed to withstand effects of cyclic loads due to system pressure and temperature changes. These loads are Introduced by startup (heatup) and shutdown (cooldown) operations, power transients, and reactor trips. This LCO limits the pressure and temperature changes during RCS heatup and cooldown, within the design assumptions and the stress limits for cyclic operation.

The PTLR contains PIT limit curves for heatup, cooldown, inservice leak and hydrostatic (ISLH) testing, and data for the maximum rate of change of reactor coolant temperature (Ref. 1).

Each PIT limit curve defines an acceptable region for normal operation. The usual use of the curves is operational guidance during heatup or cooldown maneuvering, when pressure and temperature indications are monitored and compared to the applicable curve to determine that operation is within the allowable region.

The LCO establishes operating limits that provide a margin to brittle failure of the reactor vessel and piping of the reactor coolant pressure boundary (RCPB). The vessel is the component most subject to brittle failure, and the LCO limits apply mainly to the vessel. The limits do not apply to the pressurizer, which has different design characteristics and operating functions. The reactor vessel materials have been tested to determine their initial RTNDT and the results of these tests are shown on Table B 3/4.4-1.

10 CFR 50, Appendix G (Ref. 2), requires the establishment of P/T limits for specific material fracture toughness requirements of the RCPB materials.

Reference 2 requires an adequate margin to brittle failure during normal operation, anticipated operational occurrences, and system hydrostatic tests. It mandates the use of the American Society of Mechanical Engineers (ASME)

Code, Section 11I, Appendix G (Ref. 3).

The neutron embrittlement effect on the material toughness Is reflected by increasing the nil ductility reference temperature (RTNDT) as exposure to neutron fluence increases.

The actual shift in the RTNDT of the vessel material will be established periodically by removing and evaluating the irradiated reactor vessel material specimens, in accordance with ASTM E 185 (Ref. 4) and Appendix H of 10 CFR 50 (Ref. 5).

The operating PIT limit curves will be adjusted, as necessary, based on the evaluation findings and the recommendations of Regulatory Guide 1.99 (Ref. 6).

SEQUOYAH UNIT 1 B 314 4-6 Amendment No. 40,157,158, 2 9 4, 2 9 7

RCS Pressure and Temperature (P/T) Limits B 3/4.4.9 BASES BACKGROUND (continued)

The P/T limit curves are composite curves established by superimposing limits derived from stress analyses of those portions of the reactor vessel and head that are the most restrictive. At any specific pressure, temperature, and temperature rate of change, one location within the reactor vessel will dictate the most restrictive limit. Across the span of the PIT limit curves, different locations are more restrictive, and, thus, the curves are composites of the most restrictive regions.

The heatup curve represents a different set of restrictions than the cooldown curve because the directions of the thermal gradients through the vessel wall are reversed. The thermal gradient reversal alters the location of the tensile stress between the outer and inner walls.

The criticality limit curve includes the Reference 2 requirement that it be 2 400 F above the heatup curve or the cooldown curve, and not less than the minimum permissible temperature for ISLH testing. However, the criticality curve is not operationally limiting; a more restrictive limit exists In LCO 3.1.1.4, ARCS Minimum Temperature for Criticality."

The consequence of violating the LCO limits is that the RCS has been operated under conditions that can result In brittle failure of the RCPB, possibly leading to a nonisolable leak or loss of coolant accident. In the event these limits are exceeded, an evaluation must be performed to determine the effect on the structural Integrity of the RCPB components. The ASME Code, Section Xl, Appendix E (Ref. 7), provides a recommended methodology for evaluating an operating event that causes an excursion outside the limits.

APPLICABLE The PIT limits are not derived from Design Basis Accident (DBA)

SAFETY ANALYSES analyses. They are prescribed during normal operation to avoid encountering pressure, temperature, and temperature rate of change conditions that might cause undetected flaws to propagate and cause nonductile failure of the RCPB, an unanalyzed condition.

Reference I establishes the methodology for determining the P/T limits.Although the PIT limits are not derived from any DBA, the P/T limits are acceptance limits since they preclude operation in an unanalyzed condition.

R RCS PIT limits satisfy Criterion 2 of 10 CFR 50.36(c )(2)(ii).

LCO The two elements of this LCO are:

a. The limit curves for heatup, cooldown, and ISLH testing; and

b. Limits on the rate of change of temperature.

SEQUOYAH UNIT 1 B 3/4 4-7 Amendment No.40,157, 158, 294, 297 It

RCS Pressure and Temperature (PIT) Limits B 3/4.4.9 BASES LCO (continued)

The LCO limits apply to all components of the RCS, except the pressurizer.

These limits define allowable operating regions and permit a large number of operating cycles while providing a wide margin to nonductile failure.

The limits for the rate of change of temperature control the thermal gradient through the vessel wall and are used as inputs for calculating the heatup, cooldown, and ISLH testing P/T limit curves. Thus, the LCO for the rate of change of temperature restricts stresses caused by thermal gradients and also ensures the validity of the P/T limit curves.

Violating the LCO limits places the reactor vessel outside of the bounds of the stress analyses and can Increase stresses in other RCPB components. The consequences depend on several factors, as follow:

a. The severity of the departure from the allowable operating P/T regime or the severity of the rate of change of temperature;

b. The length of time the limits were violated (longer violations allow the temperature gradient in the thick vessel walls to become more pronounced); and

c. The existences, sizes, and orientations of flaws in the vessel material.

APPLICABILITY The RCS P/T limits LCO provides a definition of acceptable operation for prevention of nonductile failure in accordance with 10 CFR 50, Appendix G (Ref. 2). Although the P/T limits were developed to provide guidance for operation during heatup or cooldown (MODES 3, 4, and 5) or ISLH testing, their Applicability is at all times In keeping with the concern for nonductile failure. The limits do not apply to the pressurizer.

During MODES 1 and 2, other Technical Specifications provide limits for operation that can be more restrictive than or can supplement these P/T limits.

Specification 3/4.2.5, 'DNB Parameters," Specification 3.1.1.4, Minimum Temperature for Criticality", and Safety Limit 2.1, "Safety Limits," also provide operational restrictions for pressure and temperature and maximum pressure.

Furthermore, MODES I and 2 are above the temperature range of concern for nonductile failure, and stress analyses have been performed for normal maneuvering profiles, such as power ascension or descent.

ACTIONS Action a Operation outside the PIT limits during MODE 1, 2, 3, or 4 must be corrected so that the RCPB is returned to a condition that has been verified by stress analyses.

SEQUOYAH UNIT 1 B 3/4 4-8 AmendmentNo.40, 157, 158, 294, 297

RCS Pressure and Temperature (PIT) Limits B 3/4.4.9 BASES ACTIONS (continued)

The 30 minute action time reflects the urgency of restoring the parameters to within the analyzed range. Most violations will not be severe, and the activity can be accomplished In this time in a controlled manner.

Besides restoring operation within limits, an evaluation is required to determine if RCS operation can continue. The evaluation must verify the RCPB integrity remains acceptable and must be completed before continuing operation. Several methods may be used, including comparison with pre-analyzed transients in the stress analyses, new analyses, or inspection of the components.

ASME Code, Section Xl, Appendix E (Ref. 7), may be used to support the evaluation. However, its use is restricted to evaluation of the vessel beltline.

The 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> action time Is reasonable to accomplish the evaluation. The evaluation for a mild violation is possible within this time, but more severe violations may require special, event specific stress analyses or inspections. A favorable evaluation must be completed before continuing to operate.

Action (a) is modified by a footnote requiring an evaluation of RCS acceptability to be completed whenever the action is entered. The footnote emphasizes the need to perform the evaluation of the effects of the excursion outside the allowable limits. Restoration alone Is insufficient because higher than analyzed stresses may have occurred and may have affected the RCPB integrity.

If Action (a) is not met, the plant must be placed In a lower MODE because either the RCS remained In an unacceptable PIT region for an extended period of increased stress or a sufficiently severe event caused entry into an unacceptable region. Either possibility indicates a need for more careful examination of the event, best accomplished with the RCS at reduced pressure and temperature. In reduced pressure and temperature conditions, the possibility of propagation with undetected flaws is decreased.

If the required restoration activity cannot be accomplished within 30 minutes, the action must be implemented to reduce pressure and temperature.

If the required evaluation for continued operation cannot be accomplished within 72 hours3 days <br />0.429 weeks <br />0.0986 months <br /> or the results are Indeterminate or unfavorable, action must proceed to reduce pressure and temperature. A favorable evaluation must be completed and documented before returning to operating pressure and temperature conditions.

Pressure and temperature are reduced by bringing the plant to MODE 3 within 6 hours0.25 days <br />0.0357 weeks <br />0.00822 months <br /> and to MODE 5 with RCS pressure < 500 psig within 36 hours1.5 days <br />0.214 weeks <br />0.0493 months <br />.

The allowed action times are reasonable, based on operating experience, to reach the required plant conditions from full power conditions in an orderly manner and without challenging plant systems.

SEQUOYAH UNIT I B 3/4 4-9 Amendment No. 40, 157, 158, 294, 297

RCS Pressure and Temperature (P/T) Limits B 3/4.4.9 BASES ACTIONS (continued)

Action b Actions must be initiated immediately to correct operation outside of the P/T limits at times other than when in MODE 1, 2, 3, or 4, so that the RCPB is returned to a condition that has been verified by stress analysis.

The immediate action time reflects the urgency of initiating action to restore the parameters to within the analyzed range. Most violations will not be severe, and the activity can be accomplished in this time in a controlled manner.

Besides restoring operation within limits, an evaluation is required to determine if RCS operation can continue. The evaluation must verify that the RCPB Integrity remains acceptable and must be completed prior to entry into MODE 4. Several methods may be used, Including comparison with pre-analyzed transients in the stress analyses, or inspection of the components.

ASME Code, Section Xl, Appendix E (Ref. 7), may be used to support the evaluation. However, its use is restricted to evaluation of the vessel beltline.

Action b Is modified by a footnote requiring an evaluation of RCS acceptability to be completed whenever the action is entered. The footnote emphasizes the need to perform the evaluation of the effects of the excursion outside the allowable limits. Restoration alone is insufficient because higher than analyzed stresses may have occurred and may have affected the RCPB integrity.

SURVEILLANCE 4.4.9.1.1 REQUIREMENTS Verification that operation Is within the PTLR limits is required every 30 minutes when RCS pressure and temperature conditions are undergoing planned changes. This frequency Is considered reasonable In view of the control room indication available to monitor RCS status. Also, since temperature rate of change limits are specified in hourly increments, 30 minutes permits assessment and correction for minor deviations within a reasonable time.

Surveillance for heatup, cooldown, or ISLH testing may be discontinued when the definition given in the relevant plant procedure for ending the activity Is satisfied.

This SR is modified by a footnote that only requires this SR to be performed during system heatup, cooldown, and ISLH testing. No SR is given for criticality operations because LCO 3.1.1.4 contains a more restrictive requirement.

SEQUOYAH UNIT 1 B 3/4 4-10 Amendment No. 40, 157, 158, 294, 297

RCS Pressure and Temperature (PIT) Limits B 3/4.4.9 BASES

REFERENCES:

1. WCAP-7924-A,April 1975

2. 10 CFR 50, Appendix G.

3. ASME, Boiler and Pressure Vessel Code, Section 1II, Appendix G.

4. ASTM E 185-82, July 1982.

5. 10 CFR 50, Appendix H.

6. Regulatory Guide 1.99, Revision 2, May 1988.

7. ASME, Boiler and Pressure Vessel Code,Section XI, Appendix E.

8. WCAP-15293, OSequoyah Unit 1 Heatup and Cooldown Limit Curves for Normal Operation and PTLR Support Documentation."

SEQUOYAH UNIT I B 3/4 4-11 Amendment No.40,157,158,294, 297

RCS Pressure and Temperature (PIT) Limits B 3/4.4.9 TABLE B 3/4.4-1 SEQUOYAH-UNIT 1 REACTOR VESSEL TOUGHNESS DATA MATERIAL Cu Ni NDT MINIMUM RTNDT AVERAGE UPPER COMPONENT HEAT NO. GRADE (%) (%) (°F) 50 ft-lb/35 mil temp. (OF) SHELF ENERGY TEMP.(°F) (ft-lb)

PMWD1 NMWD2 PMWD1 NMWD2 Clos Hd. Dome 52841-1 A533B,C1.1 - - -40 +14 +34 -26 1o4a Clos Hd. Ring (D75600) A508,C1.2 - - +5 +36 +56* +5 125a Hd Flange 4842 A508,C1.2 - - -40 -24 -4* -40 131a Vessel Flange 4866 A508,C1.2 - - -49 -47 -27 -49 158a Inlet Nozzle 4846 A508,C1.2 - - -58 +25 +45 -15 94.5 -

Inlet Nozzle 4949 A508,C1.2 - - -40 +39 +59* -1 93 a 1 18 Inlet Nozzle 4863 A508,C1.2 - - -22 +16 +36* -22 a -

Inlet Nozzle 4865 A508,C1.2 - - -67 +9 +29- -31 94a Outlet Nozzle 4845 A508,C1.2 - - -49 +21 +41- -19 94 a Outlet Nozzle 4850 A508,C1.2 - - -58 +30 +50* -10 79 5a 103 Outlet Nozzle 4862 A508,C1.2 - - -58 +16 +36* -24 a Outlet Nozzle 4864 A508,C1.2 - - -49 0 +20 -40 126a -

UpperShell 4841 A508,C1.2 - - -40 +43 +83 +23 83 113' Inter Shell 4829 A508,C1.2 0.15 0.86 -4 +10 +100 +40 116 7 3bsc Lower Shell 4836 A508,C1.2 0.13 0.76 +5 +28 +133 +73 10 70' Trans. Ring 4879 A508,C1.2 - - +5 +27 +47* +5 98 a Bot. Hd. Rim 52703/2-1 A533BC1.1 - - -31 +23 +43* -17 104-a Bot. Hd. Rim 5270312-2 A533BC1.1 - - -13 +36 +56* -4 63 a Bot. Hd. Rim 52704/2 A533B,C1.1 - - -49 -24 -4* -49 114a Bot. Hd. Rim 52703/2-2 A533B,C1.1 - - -31 +43 +63* +3 86 a Bot. Hd. Rim 52704/2 A533B,C1.1 - - -58 -13 +4 -53 120a Bot. Hd. 52704/11 A533B,C1.1 - - -58 -47 -27* -58 139 Weld - Weld 0.33 .017 -40 - -4 -40 - 116 HAZ - Weld - - -22 - +41 -19 - 8 6b 1-Paralled to Major Working Direction a-%Shear Not reported c-Minimum upper shelf energy decreased to 51 at a test 2-Normal to Major Working Direction b-Minimum upper shelf energies temperature of 300°F. This anomaly will be reevaluted

• Estimate based on USAEC Regulatory Standard Review Plan, Section 5.3.2 when the results of Generic task A-11 MTEB are available.

SEQUOYAH UNIT 1 B 3/4 4-12 Amendment No. 158, 2 9 4, 2 9 7 1

REACTOR COOLANT SYSTEM BASES 3/4.4.10 DELETED 3/4.4.11 REACTOR COOLANT SYSTEM HEAD VENTS The function of the RCS head vents is to remove non-condensables or steam from the reactor vessel head. This system is designed to mitigate a possible condition of inadequate core cooling, inadequate natural circulation, or inability to depressurize the RHR System initiated conditions resulting from the accumulation of non-condensable gases in the Reactor Coolant System. The reactor vessel head vent is designed with redundant safety grade vent paths.

SEQUOYAH - UNIT I B 3/4 4-13 Amendment No. 116,133,157,208, 294,297

LTOP System B 3/4.4.12 REACTOR COOLANT SYSTEM BASES B 3/4.4 REACTOR COOLANT SYSTEM B 3/4.4.12 Low Temperature Overpressure Protection (LTOP) System BACKGROUND The LTOP System controls RCS pressure at low temperatures so the integrity of the reactor coolant pressure boundary (RCPB) is not compromised by violating the pressure and temperature (PIT) limits of 10 CFR 50, Appendix G (Ref. 1).

The reactor vessel is the limiting RCPB component for demonstrating such protection. The PTLR provides the maximum allowable actuation logic setpoints for the power operated relief valves (PORVs) and the maximum RCS pressure for the existing RCS cold leg temperature during cooldown, shutdown, and heatup to meet the Reference 1 requirements during the LTOP MODES.

The reactor vessel material is less tough at low temperatures than at normal operating temperature. As the vessel neutron exposure accumulates, the material toughness decreases and becomes less resistant to pressure stress at low temperatures (Ref. 2). RCS pressure, therefore, is maintained low at low temperatures and is increased only as temperature is increased.

The potential for vessel overpressurization Is most acute when the RCS is water solid, occurring only while shutdown; a pressure fluctuation can occur more quickly than an operator can react to relieve the condition. Exceeding the RCS PIT limits by a significant amount could cause brittle cracking of the reactor vessel. LCO 3.4.9.1, "RCS Pressure and Temperature (PIT) Limits," requires administrative control of RCS pressure and temperature during heatup and cooldown to prevent exceeding the PTLR limits.

This LCO provides RCS overpressure protection by having a minimum coolant input capability and having adequate pressure relief capacity. Limiting coolant input capability requires all but one charging pump incapable of injection into the RCS and isolating the accumulators. The pressure relief capacity requires either two redundant PORVs or a depressurized RCS and an RCS vent of sufficient size. One PORV or the open RCS vent is the overpressure protection device that acts to terminate an Increasing pressure event.

With minimum coolant input capability, the ability to provide core coolant addition is restricted. The LCO does not require the makeup control system deactivated or the safety Injection (SI) actuation circuits blocked. Due to the lower pressures in the LTOP MODES and the expected core decay heat levels, the makeup system can provide adequate flow via the makeup control valve. If conditions require the use of more than one charging pump for makeup in the event of loss of inventory, then pumps can be made available through manual actions.

The LTOP System for pressure relief consists of two PORVs with reduced lift settings, or a depressurized RCS and an RCS vent of sufficient size. Two PORVs are required for redundancy. One PORV has adequate relieving capability to keep from overpressurization for the required coolant input capability.

SEQUOYAH UNIT I B 3/4 4-14 Amendment No. 116,133,157,208, 294, 297

LTOP System B 3/4.4.12 BASES Background (continued)

PORV Requirements As designed for the LTOP System, each PORV is signaled to open if the RCS pressure approaches a limit determined by the LTOP actuation logic. The LTOP actuation logic monitors both RCS temperature and RCS pressure and determines when a condition not acceptable in the PTLR limits is approached.

The wide range RCS temperature indications are auctioneered to select the lowest temperature signal.

The lowest temperature signal is processed through a function generator that calculates a pressure limit for that temperature. The calculated pressure limit is then compared with the Indicated RCS pressure from a wide range pressure channel. If the indicated pressure meets or exceeds the calculated value, a PORV is signaled to open.

The PTLR presents the PORV setpoints for LTOP. The setpoints are normally staggered so only one valve opens during a low temperature overpressure transient. Having the setpoints of both valves within the limits in the PTLR ensures that the Reference I limits will not be exceeded in any analyzed event.

When a PORV is opened In an increasing pressure transient, the release of coolant will cause the pressure increase to slow and reverse. As the PORV releases coolant, the RCS pressure decreases until a reset pressure is reached and the valve is signaled to close. The pressure continues to decrease below the reset pressure as the valve closes.

RCS Vent Requirements Once the RCS is depressurized, a vent exposed to the containment atmosphere will maintain the RCS at containment ambient pressure in an RCS overpressure transient, if the relieving requirements of the transient do not exceed the capabilities of the vent. Thus, the vent path must be capable of relieving the flow resulting from the limiting LTOP mass or heat input transient, and maintaining pressure below the PIT limits. The required vent capacity may be provided by one or more vent paths.

For an RCS vent to meet the flow capacity requirement, It requires an RCS vent opening of at least three square Inches. This may be accomplished by removing a pressurizer safety valve, removing a PORV's internals, and disabling its block valve in the open position. The vent path(s) must be above the level of reactor coolant, so as not to drain the RCS when open.

APPLICABLE Safety analyses (Ref. 4) demonstrate that the reactor vessel is SAFETY adequately protected against exceeding the Reference 1 P/T limits. In ANALYSES MODES 1, 2, and 3, and in MODE 4 with RCS cold leg temperature exceeding the LTOP arming temperature specified in the PTLR , the pressurizer safety valves will prevent RCS pressure from exceeding the Reference 1 limits.

SEQUOYAH UNIT 1 B 3/4 4-1 5 Amendment No. 116,133,157,208,294,297 I

LTOP System B 3/4.4.12 BASES APPLICABLE SAFETY ANALYSES (continued)

At about the LTOP arming temperature specified in the PTLR and below, overpressure prevention falls to two OPERABLE PORVs or to a depressurized RCS and a sufficient sized RCS vent. Each of these means has a limited overpressure relief capability. The actual temperature at which the pressure in the P/T limit curve falls below the pressurizer safety valve setpoint increases as the reactor vessel material toughness decreases due to neutron embrittlement. Each time the PTLR curves are revised, the LTOP System must be re-evaluated to ensure its functional requirements can still be met using the PORV method or the depressurized and vented RCS condition.

The PTLR contains the acceptance limits that define the LTOP requirements.

Any change to the RCS must be evaluated against the Reference 4 analyses to determine the impact of the change on the LTOP acceptance limits.

Transients that are capable of overpressurizing the RCS are categorized as either mass or heat input transients, examples of which follow:

Mass InDut Tvye Transients

a. Inadvertent safety injection; or

b. Charging/letdown flow mismatch.

Heat Input Tvye Transients

a. Inadvertent actuation of pressurizer heaters;

b. Loss of RHR cooling; or

c. Reactor coolant pump (RCP) startup with temperature asymmetry within the RCS or between the RCS and steam generators.

The following are required during the LTOP MODES to ensure that mass and heat input transients do not occur, which either of the LTOP overpressure protection means cannot handle:

a. Rendering all but one charging pump incapable of injection;

b. Deactivating the accumulator discharge isolation valves in their closed positions; and

c. Disallowing start of an RCP unless a steam bubble exists in the pressurizer.

LCO 3.4.1.3, "Reactor Coolant System- Hot Shutdown," provides this protection.

SEQUOYAH UNIT 1 B 3/4 4-1 6 Amendment No.116,133,157,208,294 , 29 7 l

LTOP System B 314.4.12 BASES APPLICABLE SAFETY ANALYSES (continued)

The Reference 4 analyses demonstrate that either one PORV or the depressurized RCS and RCS vent can maintain RCS pressure below limits when only one charging pump is actuated. Thus, the LCO allows only one charging pump OPERABLE during the LTOP MODES. Since neither one PORV nor the RCS vent can handle the pressure transient need from accumulator injection, when RCS temperature Is low, the LCO also requires the accumulators isolated when accumulator pressure Is greater than or equal to the maximum RCS pressure for the existing RCS cold leg temperature allowed in the PTLR.

The isolated accumulators must have their discharge valves closed and the valve power supply breakers fixed in their open positions.

Fracture mechanics analyses establish the temperature of LTOP Applicability at the LTOP arming temperature specified in the PTLR.

The consequences of a small break loss of coolant accident (LOCA) in LTOP MODE 4 conform to 10 CFR 50.46 and 10 CFR 50, Appendix K (Refs. 5 and 6),

requirements by having a maximum of one charging pump OPERABLE and Si actuation enabled.

PORV Performance The fracture mechanics analyses show that the vessel is protected when the PORVs are set to open at or below the limit shown in the PTLR. The setpoints are derived by analyses that model the performance of the LTOP System, assuming the limiting LTOP transient Is one charging pump injecting into the RCS. These analyses consider pressure overshoot and undershoot beyond the PORV opening and closing, resulting from signal processing and valve stroke times. The PORV setpoints at or below the derived limit ensures the Reference 1 P/T limits will be met.

The PORV setpoints Inthe PTLR will be updated when the revised P/T limits conflict with the LTOP analysis limits. The P/T limits are periodically modified as the reactor vessel material toughness decreases due to neutron embrittlement caused by neutron irradiation.

Revised limits are determined using neutron fluence projections and the results of examinations of the reactor vessel material irradiation surveillance specimens. The Bases for LCO 3.4.9.1 'RCS Pressure and Temperature (PIT) Limits," discuss these examinations.

The PORVs are considered active components. Thus, the failure of one PORV is assumed to represent the worst case, single active failure.

SEQUOYAH UNIT 1 B 3/4 4-17 Amendment No. 116,133, 157,208,2 94, 297

LTOP System B 314.4.12 BASES APPLICABLE SAFETY ANALYSES (continued)

RCS Vent Performance With the RCS depressurized, analyses show a vent size of 3.0 square inches is capable of mitigating the allowed LTOP overpressure transient. The capacity of a vent this size is greater than the flow of the limiting transient for the LTOP configuration, one charging pump OPERABLE, maintaining RCS pressure less than the maximum pressure on the P/T limit curve.

The RCS vent size will be re-evaluated for compliance each time the P/T SAFETY limit curves are revised based on the results of the vessel material surveillance.

The RCS vent is passive and is not subject to active failure.

The LTOP System satisfies Criterion 2 of 10 CFR 50.36(c)(2)(ii).

LCO This LCO requires that the LTOP System is OPERABLE. The LTOP System is OPERABLE when the minimum coolant input and pressure relief capabilities are OPERABLE. Violation of this LCO could lead to the loss of low temperature overpressure mitigation and violation of the Reference 1 limits as a result of an operational transient.

To limit the coolant Input capability, the LCO requires that a maximum of one charging pump and no safety Injection pumps be capable of injecting into the RCS, and all accumulator discharge isolation valves be closed and immobilized when accumulator pressure Is greater than or equal to the maximum RCS pressure for the existing RCS cold leg temperature allowed in the PTLR.

The LCO is modified by three footnotes. The first footnote allows two charging pumps to be made capable of injecting for

• 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> during pump swap operations. One hour provides sufficient time to safely complete the actual transfer and to complete the administrative controls and surveillance requirements associated with the swap. The intent is to minimize the actual time that more than one charging pump is physically capable of injection. The second footnote states that accumulator may be unisolated when the accumulator pressure is less than the maximum RCS pressure for the existing RCS cold leg temperature allowed by the P/T limit curves provided in the PTLR. This footnote permits the accumulator discharge isolation valve surveillance to be performed only under these pressure and temperature conditions. The third footnote allows a 4-hour maximum time period for rendering both safety injection pumps and one centrifugal charging pump inoperable after entry to MODE 4 from MODE 3. RCS temperature must remain above 3250 F until the pumps are rendered incapable of inadvertent injection. The 4-hour time period is sufficient for completing this activity and is based on the low probability for inadvertent pump start.

The elements of the LCO that provide low temperature overpressure mitigation through pressure relief are:

SEQUOYAH UNIT 1 B 3/44-18 Amendment No.116,133,157,208,294, 297 I

LTOP System B 3/4.4.12 BASES LCO (continued)

a. Two OPERABLE PORVs, A PORV is OPERABLE for LTOP when its block valve is open, its lift setpoint is set to the limit required by the PTLR and testing proves its ability to open at this setpoint, and motive power is available to the two valves and their control circuits.

b. A depressurized RCS and an RCS vent.

An RCS vent is OPERABLE when open with an area of 23.0 square inches.

Each of these methods of overpressure prevention is capable of mitigating the limiting LTOP transient.

APPLICABILITY This LCO is applicable in MODE 4 when any RCS cold leg temperature is

• the LTOP arming temperature specified in the PTLR, In MODE 5, and in MODE 6 when the reactor vessel head is on. The pressurizer safety valves provide overpressure protection that meets the Reference 1 P/T limits above the LTOP arming temperature specified in the PTLR. When the reactor vessel head is off, overpressurization cannot occur.

LCO 3.4.9.1 provides the operational P/T limits for all MODES.

LCO 3.4.3.1, "Pressurizer Safety Valves," requires the OPERABILITY of the pressurizer safety valves that provide overpressure protection during MODES 1, 2, and 3, and MODE 4 with all RCS cold leg temperatures above the LTOP arming temperature specified In the PTLR.

Low temperature overpressure prevention is most critical during shutdown when the RCS is water solid, and a mass or heat input transient can cause a very rapid increase in RCS pressure when little or no time allows operator action to mitigate the event.

ACTIONS Action a With any safety injection pump or more than one centrifugal charging pumps capable of injecting into the RCS, RCS overpressurization is possible.

To immediately initiate action to restore restricted coolant input capability to the RCS reflects the urgency of removing the RCS from this condition.

Action b An unisolated accumulator requires isolation within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />. This is only required when the accumulator pressure is at or more than the maximum RCS pressure for the existing temperature allowed by the P/T limit curves.

SEQUOYAH UNIT I B 3/4 4-19 Amendment No. 116,133, 157, 208,294, 297

LTOP System B 3/4.4.12 BASES ACTIONS (continued)

If isolation is needed and cannot be accomplished in 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />, two options are provided either of which must be performed in the next 12 hours0.5 days <br />0.0714 weeks <br />0.0164 months <br />. By increasing the RCS temperature to > LTOP arming temperature specified in the PTLR, an accumulator pressure of 600 psig cannot exceed the LTOP limits if the accumulators are fully injected. Depressurizing the accumulators below the LTOP limit from the PTLR also gives this protection.

The action times are based on operating experience that these activities can be accomplished in these time periods and on engineering evaluations Indicating that an event requiring LTOP is not likely in the allowed times.

Action c In MODE 4 when any RCS cold leg temperature is

• the LTOP arming temperature specified In the PTLR, with one required PORV Inoperable, the required PORV must be restored to OPERABLE status within 7 days. Two PORVs are required to provide low temperature overpressure mitigation while withstanding a single failure of an active component.

The action time considers the facts that only one of the PORVs is required to mitigate an overpressure transient and that the likelihood of an active failure of the remaining valve path during this time period is very low.

Action d The consequences of operational events that will overpressurize the RCS are more severe at lower temperature (Ref. 7). Thus, with one of the two PORVs inoperable in MODE 5 or in MODE 6 with the head on, the action time to restore two valves to OPERABLE status is 24 hours1 days <br />0.143 weeks <br />0.0329 months <br />.

The action time represents a reasonable time to investigate and repair several types of PORV failures without exposure to a lengthy period with only one OPERABLE PORV to protect against overpressure events.

Action e The RCS must be depressurized and a vent must be established within 12 hours0.5 days <br />0.0714 weeks <br />0.0164 months <br /> when:

a. Both required PORVs are inoperable;

b. Actions a, c, or d are not completed in the allowable times; or

c. The LTOP System is inoperable for any reason other than Actions a, b, c or d.

SEQUOYAH UNIT I B 3/4 4-20 Amendment No. 116, 133, 157, 208,2 94, 297 I

LTOP System B 3/4.4.12 BASES ACTIONS (continued)

The vent must be sized 2 3.0 square inches to ensure that the flow capacity is greater than that required for the worst case mass input transient reasonable during the applicable MODES. This action is needed to protect the RCPB from a low temperature overpressure event and a possible brittle failure of the reactor vessel.

The action time considers the time required to place the plant in this condition and the relatively low probability of an overpressure event during this time period due to increased operator awareness of administrative control requirements.

SURVEILLANCE 4.4.12.1.a REQUIREMENTS Performance of a CHANNEL FUNCTIONAL TEST is required within 12 hours0.5 days <br />0.0714 weeks <br />0.0164 months <br /> after decreasing RCS cold leg temperature to

• LTOP arming temperature specified Inthe PTLR and every 31 days on each required PORV to verify and, as necessary, adjust its lift setpoint. The CHANNEL FUNCTIONAL TEST will verify the setpoint is within the PTLR allowed maximum limits in the PTLR. PORV actuation could depressurize the RCS and is not required.

The 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> frequency considers the unlikelihood of a low temperature overpressure event during this time.

A footnote* has been added indicating that this SR is required to be performed 12 hours0.5 days <br />0.0714 weeks <br />0.0164 months <br /> after decreasing RCS cold leg temperature to

• LTOP arming temperature specified in the PTLR. The CHANNEL FUNCTIONAL TEST cannot be performed until In the LTOP MODES when the PORV lift setpoint can be reduced to the LTOP setting. The test must be performed within 12 hours0.5 days <br />0.0714 weeks <br />0.0164 months <br /> after entering the LTOP MODES.

4.4.12.1.b Performance of a CHANNEL CALIBRATION on each required PORV actuation channel is required every 18 months to adjust the whole channel so that it responds and the valve opens within the required range and accuracy to known input.

4.4.12.1.c The PORV block valve must be verified open every 72 hours3 days <br />0.429 weeks <br />0.0986 months <br /> to provide the flow path for each required PORV to perform its function when actuated. The valve must be remotely verified open In the main control room.

The block valve is a remotely controlled, motor operated valve. The power to the valve operator is not required removed, and the manual operator is not required locked in the inactive position. Thus, the block valve can be closed in the event the PORV develops excessive leakage or does not close (sticks open) after relieving an overpressure situation.

SEQUOYAH UNIT 1 B 3/4 4-21 Amendment No. 116,133, 157, 208,2 94, 297 I

LTOP System B 3/4.4.12 BASES SURVEILLANCE REQUIREMENTS (continued)

The 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> frequency is considered adequate in view of other administrative controls available to the operator in the control room, such as valve position indication, that verify that the PORV block valve remains open.

4.4.12.2 and 4.4.12.3 To minimize the potential for a low temperature overpressure event by limiting the mass input capability, all safety injection pumps and all but one charging pump are verified incapable of injecting into the RCS and the accumulator discharge isolation valves are verified closed and locked out The safety injection pumps and charging pumps are rendered incapable of injecting into the RCS through removing the power from the pumps by racking the breakers out under administrative control. An alternate method of LTOP control may be employed using at least two independent means to prevent a pump start such that a single failure or single action will not result in an injection into the RCS. This may be accomplished through the pump control switch being placed in pull-to-lock and at least one valve in the discharge flow path being closed.

The frequency of 12 hours0.5 days <br />0.0714 weeks <br />0.0164 months <br /> is sufficient, considering other indications and alarms available to the operator in the control room, to verify the required status of the equipment.

4.4.12.4 The accumulator discharge isolation valves are verified closed and locked out at least once per 12 hours0.5 days <br />0.0714 weeks <br />0.0164 months <br />. The frequency of 12 hours0.5 days <br />0.0714 weeks <br />0.0164 months <br /> is sufficient considering other Indications and alarms available to the operator in the control room to verify the required status of the equipment.

4.4.12.5 The RCS vent of 2 3.0 square inches is proven OPERABLE by verifying its open condition either.

a. Once everyl2 hours0.0833 days <br />0.0119 weeks <br />0.00274 months <br /> for a valve that is not locked. (valves that are sealed or secured in the open position are considered "locked' in this context).

b. Once every 31 days for other vent path(s) (e.g., a vent valve that is locked, sealed, or secured in position or a removed pressurizer safety valve or open manway also fits this category.

The passive vent path arrangement must only be open to be OPERABLE. This surveillance is required to be met if the vent is being used to satisfy the pressure relief requirements of the LCO 3.4.12.b.

SEQUOYAH UNIT 1 B 3/4 4-22 Amendment No.116,133,157,208,294, 297

LTOP System B 3/4.4.12 BASES REFERENCES 1. 10 CFR 50, Appendix G

2. Generic Letter 88-1 1.

3. ASME, Boiler and Pressure Vessel Code, Section Ill.

4. FSAR, Chapter 15

5. 10 CFR 50, Section 50.46.

6. 10 CFR 50, Appendix K.

7. Generic Letter 90-06.

8. ASME, Boiler and Pressure Vessel Code,Section XI.

SEQUOYAH UNIT 1 B 3/4 4-23 Amendment No. 116, 133,157, 208,2 94, 297

ADMINISTRATIVE CONTROLS CORE OPERATING LIMITS REPORT (continued)

6. WCAP-10054-P-A, Westinghouse Small Break ECCS Evaluation Model Using the NOTRUMP Code, August 1985, (W Proprietary)

(Methodology for Specification 3/4.2.2 - Heat Flux Hot Channel Factor)

7. WCAP-10266-P-A, Rev. 2, "THE 1981 REVISION OF WESTINGHOUSE EVALUATION MODEL USING BASH CODE", March 1987, (W Proprietary).

(Methodology for Specification 3.2.2 - Heat Flux Hot Channel Factor).

8. BAW-10227P-A, 'Evaluation of Advance Cladding and Structural Material (M5) in PWR Reactor Fuel,' February 2000, (FCF Proprietary)

(Methodology for Specification 3/4.2.2 - Heat Flux Hot Channel Factor) 6.9.1.14.b The core operating limits shall be determined so that all applicable limits (e.g., fuel thermal-mechanical limits, core thermal-hydraulic limits, ECCS limits, nuclear limits such as shutdown margin, and transient and accident analysis limits) of the safety analysis are met.

6.9.1.14.c THE CORE OPERATING LIMITS REPORT shall be provided within 30 days after cycle start-up (Mode 2) for each reload cycle or within 30 days of issuance of any midcycle revision of the NRC Document Control Desk with copies to the Regional Administrator and Resident Inspector.

REACTOR COOLANT SYSTEM (RCS) PRESSURE AND TEMPERATURE LIMITS (PTLR) REPORT 6.9.1.15 RCS pressure and temperature limits for heatup, cooldown, low temperature operation, criticality, and hydrostatic testing, LTOP arming, and PORV lift settings as well as heatup and cooldown rates shall be established and documented in the PTLR for the following:

Specification 3.4.9.1, 'RCS Pressure and Temperature (P/T) Limits" Specification 3.4.12, 'Low Temperature Over Pressure Protection (LTOP) System" 6.9.1.15.a The analytical methods used to determine the RCS pressure and temperature limits shall be those previously reviewed and approved by the NRC, specifically those described in the following documents:

1. Westinghouse Topical Report WCAP-14040-NP-A, "Methodology used to Develop Cold Overpressure Mitigating System Setpoints and RCS Heatup and Cooldown Limit Curves."

2. Westinghouse Topical Report WCAP-15293, 'Sequoyah Unit I Heatup and Cooldown Limit Curves for Normal Operation and PTLR Support Documentation."

3. Westinghouse Topical Report WCAP-1 5984, "Reactor Vessel Closure Head/Vessel Flange Requirements Evaluation for Sequoyah Units I and 2."

6.9.1.15.b The PTLR shall be provided to the NRC within 30 days of issuance of any revision or supplement thereto.

SPECIAL REPORTS 6.9.2.1 Special reports shall be submitted within the time period specified for each report, in accordance with 10 CFR 50.4.

6.9.2.2 This specification has been deleted.

SEQUOYAH - UNIT 1 6-13a Amendment No. 52, 58, 72, 74, 117, 155,223,241, 258, 294, 297

NULA UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 297 TO FACILITY OPERATING LICENSE NO. DPR-77 TENNESSEE VALLEY AUTHORITY SEQUOYAH NUCLEAR PLANT. UNIT 1 DOCKET NO. 50-327.

1.0 INTRODUCTION

By letter dated November 4, 2004, Tennessee Valley Authority (TVA, the licensee) requested an extension to the implementation period for Technical Specification (TS) Change 00-14 to May 15, 2005, from the original implementation period of the completion of the 2004 Cycle 13 refueling outage (License Amendment No. 294 for Sequoyah Nuclear Plant (SQN) Unit 1).

Tennessee Valley Authority (TVA) requested the change in implementation date on an emergency basis based on unforseen difficulties associated with the calibration of the low-temperature overpressure protection (LTOP) system setpoints. There are no proposed changes to the TSs.

2.0 BACKGROUND

By letter dated September 15, 2004, U. S. Nuclear Regulatory Commission (NRC) issued License Amendment Nos. 294 and 284 for SON TS Change 00-14 (Units 1 and 2, respectively).

The amendments revised the TS reactor coolant system (RCS) pressure-temperature limits and the LTOP setpoints for each unit. These amendments were requested by TVA letter dated September 6, 2002. The implementation period for each amendment states:

This license amendment is effective as of its date of issuance, to be implemented by the completion of the 2004 Sequoyah Unit 1 Cycle 13 Refueling Outage.

TVA requested that implementation requirements of SQN Unit 1 Amendment 294 be amended as follows:

This license amendment is effective as of its date of issuance, to be implemented by May 15, 2005.

TVA has encountered unforeseen difficulties associated with calibration of the electronic modules that control the new Unit 1 LTOP system setpoints as provided in TS Change 00-14.

In addition, TVA discovered that a spare module would not calibrate to the new LTOP setpoints and must be shipped back to the vendor for refurbishment. Refurbishment of the spare module will not be available from the vendor in time to support TVA's schedule for startup from the ENCLOSURE