ML20070H413
| ML20070H413 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 07/12/1994 |
| From: | Beckner W Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20070H418 | List: |
| References | |
| NUDOCS 9407210277 | |
| Download: ML20070H413 (14) | |
Text
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E UNITED STATES 5t i!
NUCLEAR REGULATORY COMMISSION
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WASHINGTON, D.C. 20555-0001 s,,*
HOUSTON LIGHTING & POWER COMPANY CITY PUBLIC SERVICE BOARD OF SAN ANTONIO CENTRAL POWER AND LIGHT COMPANY CITY OF AUSTIN. TEXAS DOCKET NO. 50-498 SOUTH TEXAS PROJECT. UNIT 1 AMENDMENT TO FACILITY OPERATING LICENSE Amendment No. 62 License No. NPF-76 1.
The Nuclear Regulatory Commission (the Commission) has found that:
A.
The application for amendment by Houston Lighting & Power Company *
(HL&P) acting on behalf of itself and for the City Public Service Board of San Antonio (CPS), Central Power and Light Company (CPL),
and City of Austin, Texas (C0A) (the licensees), dated March 21, 1994 complies with the standards and requirements of the Atomic Energy Act of 1954, as amended (the Act), and the Commission's rules and regulations set forth in 10 CFR Chapter I; B.
The facility will operate in conformity with the application, as amended, the provisions of the Act, and the rules and regulations of the Commission; C.
There is reasonable assurance:
(i) that the activities authorized by this amendment can be conducted without endangering the health and safety of the public, and (ii) that such activities will be conducted in compliance with the Commission's regulations; D.
The issuance of this license amendment will not be inimical to the common defense and security or to the health and safety of the l
public; and-E.
The' issuance of this amendment is in accordance with 10 CFR Part 51 of the Commission's regulations and all applicable requirements have been satisfied.
- Houston Lighting & Power Company is authorized to act for the City Public Service Board of San Antonio, Central Power and Light Company and City of Austin, Texas and has exclusive responsibility and control over the physical construction, operation and maintenance of the facility.
9407210277 940712 PDR ADOCK 05000498 PDR p
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Accordingly, the license is amended by changes to the Technical Specifications as indicated in the attachment to this license amendment and Paragraph 2.C.(2) of Facility Operating License No. nFT-76 is hereby amended to read as follows:
2.
Technical Specifications The Technical Specifications contained in Appendix A, as revised through Amendment No. 62, and the Environmental Protection Plan contained in Appendix B, are hereby incorporated in the license.
The licensee shall operate the facility in accordance with the Technical Specifications and the Environmental Protection Plan.
3.
The license amendment is effective as of its date of issuance, to be implemented within 31 days of issuance.
FOR THE NUCLEAR REGULATORY COMMISSION Whap.& L William D. Beckner, Director Project Directorate IV-1 Division of Reactor Projects III/IV Office of Nuclear Reactor Regulation
Attachment:
Changes to the Technical Specifications Date of Issuance:
July 12, 1994
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UNITED STATES NUCLEAR REGULATORY COMMISSION
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HOUSTON LIGHTING & POWER COMPANY CITY PUBLIC SERVICE BOARD OF SAN ANTONIO CENTRAL POWER AND LIGHT COMPANY CITY OF AUSTIN. TEXAS DOCKET NO. 50-499 SOUTH TEXAS PROJECT. UNIT 2 AMENDMENT TO FACILITY OPERATING LICENSE Amendment No. 51 License No. NPF-80 1.
The Nuclear Regulatory Commission (the Commission) has found that:
A.
The application for amendment by Houston Lighting & Power Company *
(HL&P) acting on behalf of itself and for the Cit.v Public Service Board of San Antonio (CPS), Central Power and Light Company (CPL),.
and City of Austin, Texas (C0A) (the licensees), dated March 21, 1994, complies with the standards and requirements of the Atomic Energy Act of 1954, as amended (the Act), and the Commission's rules and regulations set forth in 10 CFR Chapter I; B.
The facility will operate in conformity with the application, as amended, the provisions of the Act, and the rules and regulations of the Commission; C.
There is reasonable assurance:
(i) that the activities authorized by this amendment can be conducted without endangering the health and safety of the public, and (ii) that such activities will be conducted in compliance with the Commission's regulations; D.
The issuance of this license amendment will not be inimical to the common defense and security or to the health and safety of the public; and E.
The issuance of this amendment is in accordance with 10 CFR Part 51.
of the Commission's regulations and all applicable requirements have been satisfied.
- Houston Lighting & Power Company is authorized to act for the City Public
+
Service Board of San Antonio, Central Power and Light Company and City of Austin, Texas and has exclusive responsibility and control over the physical' construction, operation and maintenance of the facility.
. 2.
Accordingly, the license is amended by changes to the Technical Specifications as indicated in the attachment to this license amendment and Paragraph 2.C.(2) of Facility Operating License No. NPF-80 is hereby amended to read as follows:
2.
Technical Specifications The Technical Specifications contained in Appendix A, as revised through Amendment No. 51, and the Environmental Protection Plan contained in Appendix B, are hereby incorporated in the license.
The licensee shall operate the facility in accordance with the Technical Specifications and the Environmental Protection Plan.
3.
The license amendment is effective as of its date of issuance, to be implemented within 31 days of issuance.
FOR THE NUCLEAR REGULATORY COMMISSION Wh A d. hebw William D. Beckner, Director Project Directorate IV-1 Division of Reactor Projects III/IV Office of Nuclear Reactor Regulation
Attachment:
Changes to the Technical Specifications Date of Issuance:
July 12, 1994
i l
ATTACHMENT TO LICENSE AMENDMENT NOS. 62 AND R1 FACILITY OPERATING LICENSE NOS. NPF-76 AND NPF-80 DOCKET NOS. 50-498 AND 50-499 Replace the following pages of the Appendix A Technical Specifications with the attached pages.
The revised pages are identified by Amendment number and contain marginal lines indicating the areas of change.
The corresponding overleaf pages are also provided to maintain document completeness.
REMOVE INSERT 3/4 1-9 3/4 1-9 3/4 1-11 3/4 1-11 B 3/4 1-3 8 3/4 1-3 B 3/4 1-4 8 3/4 1-4 l
B 3/4 4-14 B 3/4 4-14 B 3/4 4-14a t- -
REACTIVITY CONTROL SYSTEMS 3/4.1.2 BORATION SYSTEMS FLOW PATHS - SHUTDOWN LIMITING CONDITION FOR OPERATION 3.1.2.1 As a minimum, one of the following boron injection flow paths shall be OPERABLE and capable of being powered from an OPERABLE emergency power source:
a.
A flow path from the Boric Acid Storage System via either a boric acid transfer pump or a gravity feed connection, and a charging pump to the Reactor Coolant System if the Boric Acid Storage System is OPERABLE as given in Specification 3.1.2.5a. for MODES 5 and 6 or as given in Specification 3.1.2.6a. for MODE 4; or b.
The flow path from the refueling water storage tank via a charging pump to the Reactor Coolant System if the refueling water storage tank is OPERABLE as given in Specification 3.1.2.5b. for MODES 5 and 6 or as given in Specification 3.1.2.6b. for MODE 4.
APPLICABillTY: MODES 4*, 5*,
and 6*.
l ACTION:
With none of the above flow paths OPERABLE or capable of being powered from an OPERABLE emergency power source, suspend all operations involving CORE ALTERATIONS or positive reactivity changes.
SURVEILLANCE REQUIREMENTS 4.1.2.1 At least one of the above required flow paths shall be demonstrated OPERABLE:
a.
At least once per 7 days by verifying that the temperature of the heat traced portion of the flow path is greater than or equal to 65"F when a flow path from the boric acid tanks is used, and b.
At least once per 31 days by verifying that each valve (manual, power-operated, or automatic) in the flow path that is not locked, sealed, or otherwise secured in position, is in its correct position.
- The requirements of this specification are not applicable during charging pump testing or switching pursuant to Specification 4.1.2.3.2.
SOUTH TEXAS - UNITS 1 & 2 3/4 1-9 Unit 1 - Amendment No. 62 Unit 2 - Amendment No. 51
REACTIVITY CONTROL SYSTEMS FLOW PATHS - OPERATING LIMITING CONDITION FOR OPERATION 3.1.2.2 At least two of the following three boron injection flow paths shall be OPERABLE:
The flow path from the Boric Acid Storage System via either a boric a.
acid transfer pump or a gravity feed connection, and a charging pump to the Reactor Coolant System (RCS), and b.
Two flow paths from the refueling water storage tank via charging pumps to the RCS.
APPLICABILITY:
MODES 1, 2, and 3.*
ACTION:
With only one of the above required boron injection flow paths to the RCS OPERABLE, restore at least two boron injection flow paths to the RCS to OPERABLE status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or be in at least HOT STANDBY and borated to a SHUTOOWN MARGIN equivalent to at least the limit as shown in Figure 3.1-2 at 200 F within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />; restore at least two flow paths to OPERABLE status within the next 7 days or be in COLD SHUTDOWN within the next 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.
SURVEILLANCE RE0VIREMENTS 4.1.2.2 At least two of the above required flow paths shall be demonstrated OPERABLE:
At least once per 7 days by verifying that the temperature of the a.
heat traced portion of the flow path from the boric acid tanks is greater than or equal to 65 F when it is a required water source; b.
At least once per 31 days by verifying that each valve (manual, power operated, or automatic) in the flow path that is not locked, sealed, or otherwise secured in position, is in its correct position; At least once per 18 months during shutdown by verifying that each c.
automatic valve in the flow path actuates to its correct position on a Safety Injection test signal; and d.
At least once per 18 months by verifying that the flow path required by Specification 3.1.2.2a. delivers at least 30 gpm to the RCS.
- The provisions of Specifications 3.0.4 and 4.0.4 are not applicable for entry into MODE 3 for the charging pump declared inoperable pursuant to Specifica-tion 4.1.2.3.2 provided that the charging pump is restored to OPERABLE status within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> or prior to the temperature of one or more of the RCS cold legs exceeding 375 F, whichever comes first.
SOUTH TEXAS - UNITS 1 & 2 3/4 1-10
REACTIVITY CONTROL SYSTEMS CHARGING PUMPS - SHUTDOWN LIMITING CONDITION FOR OPERATION 3.1.2.3 One charging pump in the boron injection flow path required by Specification 3.1.2.1 shall be OPERABLE and capable of being powered from an OPERABLE emergency power source.
APPLICABILITY:
MODES 4**, 5, and 6.
ACTION:
With no charging pump OPERABLE or capable of being powered from an OPERABLE emergency power source, suspend all operations involving CORE ALTERATIONS or positive reactivity changes.
SURVEILLANCE REQUIREMENTS 4.1.2.3.1 The above required charging pump shall be demonstrated OPERABLE by verifying, on recirculation flow, that a differential pressure across the pump of greater than or equal to 2300 psid is developed when tested pursuant to Specification 4.0.5.
4.1.2.3.2 All charging pumps, excluding the above required OPERABLE pump, shall be demonstrated inoperable
- at least once per 31 days, except when the reactor vessel head is removed, by verifying that the motor circuit breakers are secured in the open position.
- An inoperable pump may be energized for testing or pump switching provided l
the discharge of the pump has been isolated from the RCS by a closed isolation valve with power removed from the valve operator, or by a manual isolation valve secured in the closed position.
Reactor coolant pump seal injection flow may be maintained during the RCS isolation process.
- The provisions of Specification 3.0.4 and 4.0.4 are not applicable for entry into MODE 4 from MODE 3 for the charging pumps declared OPERABLE pursuant to Specification 4.1.2.4 provided that a maximum of one charging pump is OPERABLE within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> after entry into MODE 4 from MODE 3 or prior to the temperature of one or more of the RCS cold legs decreasing below 325"F, whichever comes first.
SOUTH TEXAS - UNITS 1 & 2 3/4 1-11 Unit 1 - Amendment No. 62 Unit 2 - Amendment No. 51
f REACTIVITY CONTROL SYSTEMS CHARGING PUMPS - OPERATING LIMITING CONDITION FOR OPERATION At least two charging pumps shall be OPERABLE.
3.1.2.4 APPLICABILITY:
MODES 1, 2, and 3.*
ACTION:
With only one charging pump OPERABLE, restore at least two charging pumps to OPERABLE status within 7 days or be in at least HOT STANDBY and borated to a SHUTDOWN MARGIN equivalent to at least the limit as shown in Figure 3.1-2 at 200*F within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />; restore at least two charging pumps to OPERABLE status within the next 7 days or be in COLD SHUTDOWN within the next 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.
SURVEILLANCE RE0VIREMENTS At least two charging pumps shall be demonstrated OPERABLE by 4.1.2.4 verifying, on recirculation flow, that a differential pressure across each pump of greater than or equal to.2300 psid is developed when tested pursuant to Specification 4.0.5.
e
- The provisions of Specification 3.0.4 and 4.0.4 are not applicable for entry into MODE 3 for the charging pumps declared inoperable pursuant to
~
Specification 4.1.2.3.2 provided that the charging pump is restored to OPERABLE status within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> or prior to the temperature of one or more of the RCS cold legs exceeding 375*F, whichever comes first.
SOUTH TEXAS - UNITS 1 & 2 3/4 1-12 Unit 1 - Amendment No. 59 Unit 2 - Amendment No. 47
REACTIVITY CONTROL 3YSTEMS BASES BORAT10N SYSTEMS (Continued) l With the RCS temperature below 350*F, one boron injection flow l
path / source is acceptable without single failure consideration on the basis of the stable reactivity condition of the reactor and the additional restrictions prohibiting CORE ALTERATIONS and positive reactivity changes in the event the single boron injection flow path / source becomes inoperable.
The limitation for a maximum of one charging pump to be OPERABLE and the Surveillance Requirement to verify all charging pumps except the required OPERABLE pump to be inoperable below 350*F provides assurance that a mass addition pressure transient can be relieved by the operation of a single PORV.
In order to provide for charging pump testing and switching below 350*F, an allowance to have both Centrifugal Charging Pumps energized simultaneously is permitted provided the pump discharge is isolated from the RCS.
During pump switching, isolation from the RCS does not violate the requirement to have the boration flow path available below 350*F since the simultaneous energization of the two charging pumps and accompanying RCS isolation, is a momentary action under direct administrative control.
Such actions are acceptable due to the limited time the flow path is isolated, the stable reactivity of the reactor, and the restrictions prohibiting CORE ALTERATIONS and positive reactivity should the isolated flow path not be immediately realigned following the pump testing or switching.
Isolation of the RCS also precludes a cold overpressurization event during the pump switching or testing process.
Reactor Coolant Pump seal flow may be maintained during the RCS isolation process.
The boration capability required below 200*F is sufficient to provide a variable SHUTDOWN MARGIN based on the results of a boron dilution accident analysis where the SHUTDOWN MARGIN is varied as a function of RCS boron concentration after xenon decay and cooldown from 200*F to 140*F.
This condition requires 3200 gallons of 7000 ppm borated water from the boric acid storage system or 122,000 gallons of 2800 ppm borated water from the RWST for MODE 5 and 33,000 gallons of 2800 ppm borated water from the RWST for MODE 6.
The contained water volume limits include allowance for water not available because of discharge line location and other physical characteristics.
The limits on contained water volume and boron concentration of the RWST also ensure a pH value of between 7.5 and 10.0 for the solution recirculated within containment after a LOCA.
This pH band minimizes the evolution of iodine and minimizes the effect of chloride and caustic stress corrosion on mechanical systems and components.
The OPERABILITY of one Baron Injection System during REFUELING ensures that this system is available for reactivity control while in MODE 6.
SOUTH TEXAS - UNITS 1 & 2 B 3/4 1-3 Unit 1 - Amendment No. 54 64,62 7
Unit 2 - Amendment No. 40 43,51 T
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REACTIVITY CONTROL SYSTEMS BASES I
3/4.1.3 MOVABLE CONTROL ASSEMBLIES The specifications of this section ensure that:
(1) acceptable power distribution limits are maintained, (2) the minimum SHUTDOWN MARGIN is maintained, and (3) the potential effects of rod misalignment on associated accident analyses are limited.
OPERABILITY of the control rod position indicators is required to determine control rod positions and thereby ensure compliance with the control rod alignment and insertion limits.
Verification that the Digital Rod Position Indicator agrees with the demanded position within i 12 steps at 24, 4G,120, and 259 steps withdrawn for the Control Banks and 18, 234, and 259 steps withdrawn for the Shutdown Banks provides assurances that the Digital Rod Position Indicator is operating correctly over the full range of indication.
Since the Digital Rod Position Indication l
System does not indicate the actual shutdown rod position between 18 steps and 234 steps, only points in the indicated ranges are picked for verification of agreement with demanded position.
The ACTION statements which permit limited variations from the basic l
requirements are accompanied by additional restrictions which ensure that the original design criteria are met.
Misalignment of a rod requires measurement l
of peaking factors and a restriction in THERMAL POWER.
These restrictions provide assurance of fuel rod integrity during continued operation.
In addition, those safety analyses affected by a misaligned rod are reevaluated to confirm that the results remain valid during future operation.
The maximum rod drop time restriction is consistent with the assumed rod drop time used in the safety analyses. Measurement with T greater than or equal to 561*F and with all reactor coolant pumps operatin,g ensures that the y
measured drop times will be representative of insertion times experienced during a Reactor trip at operating conditions.
Control rod positions and OPERABILITY of the rod position indicators are required to be verified on a nominal basis of once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> with more i
frequent verifications required if an automatic monitoring channel is
(
These verification frequencies are adequate for assuring that the L
applicable LCOs are satisfied.
l l
t l
SOUTH TEXAS - UNITS 1 & 2 B 3/4 1-4 Unit 1 - Amendment No. 62 Unit 2 - Amendment No. 51
REACTOR COOLANT SYSTEM BASES PRESSURE / TEMPERATURE LIMITS (Continued)
I 1/4T vessel location is at a higher temperature than the fluid adjacent to the vessel 10.
This condition, of course, is not true for the steady-state situa-l tion.
It follows that at any given reactor coolant temperature, the AT i
developed during cooldown results in a higher value of K at the 1/4T location I
IR for finite cooldown rates than for steady-state operation.
Furthermore, if conditions exist such that the increase in K exceeds kit, the calculated IR allowable pressure during cooldown will be greater than the steady-state value.
i The above procedures are needed because there is no direct control on temperature at the 1/4T location; therefore, allowable pressures may unknowingly be violated if the rate of cooling is decreased at various intervals along a cooldown ramp.
The use of the composite curve eliminates this problem and l
assures conservative operation of the system for the entire cooldown period.
HEATUP I
Three separate calculations are required to determine the limit curves for finite heatup rates.
As is done in the cooldown analysis, allowable pressure-temperature relationships are developed for steady-state conditions as well as finite heatup rate conditions assuming the presence of a 1/4T defect at the inside of the vessel wall.
The thermal gradients during heatup produce compressive stresses at the inside of the wall that alleviate the l
tensile stresses produced by internal pressure.
The metal temperature at the crack tip' lags the coolant temperature; therefore,- the K f r the 1/4T crack IR during heatup is lower than the K for the 1/4T crack during steady-state IR conditions at the same coolant temperature.
During heatup, especially at the end of the transient, conditions may exist such that the effects of compressive thermal stresses and different K
's f r steady-state and finite heatup rates IR do not offset each other and the pressure-temperature curve based on steady-state conditions no longer represents'a lower bound of all similar curves for finite heatup rates when the 1/4T flaw is considered.
Therefore, both cases have to
)
be analyzed in order to assure that at any coolant temperature the lower value l
of the allowable pressure calculated for steady-state and finite heatup rates
)
is obtained.
I The second portion of the heatup analysis concerns the calculation of pressure-temperature limitations for the case in which a 1/4T deep outside surface flaw is assumed.
Unlike the situation at the vessel inside surface, the thermal gradients established at the outside surface during heatup produce stresses which are tensile in nature and thus tend to reinforce any pressure stresses present.
These thermal stresses, of course, are dependent on both the rate of heatup and the time (or coolant temperature) along the heatup ramp.
Furthermore, since the thermal stresses at the outside are tensile and SOUTH TEXAS - UNITS 1 & 2 B 3/4 4-13 Unit 1 - Amendment No. 4 l
REACTOR COOLANT SYSTEM BASES PRESSURE / TEMPERATURE LIMITS (Continued)
^
increase with increasing heatup rate, a lower bound curve cannot be defined.
Rather, each heatup rate of interest must be analyzed on an individual basis.
Following the generation of pressure-temperature curves for both the steady-state and finite heatup rate situations, the final limit curves are produced as follows.
A composite curve is constructed based on a point-by-point comparison of the steady-state and finite heatup rate data.
At any given temperature, the allowable pressure is taken to be the lesser of the three values taken from the curves under consideration.
The use of the composite curve is necessary to set conservative heatup limitations because it is possible for conditions to exist such that over the course of the heatup ramp the controlling condition switches from the inside to the outside and the pressure limit must at all times be based on analysis of the most critical criterion.
Finally, the composite curves for the heatup rate data and the cooldown rate data are adjusted for possible errors in the pressure and temperature sensing instruments by the values indicated on the respective curves.
Although the pressurizer operates in temperature ranges above those for which there is reason for concern of nonductile failure, operating limits are provided to assure compatibility of operation with the fatigue analysis performed in accordance with the ASME Code requirements.
LOW TEMPERATURE OVERPRESSURE PROTECTION The OPERAdlLITY of two PORVs or an RCS vent opening of at least 2.0 square inches ensures that the RCS will be protected from pressure transients which could exceed the limits of Appendix G to 10 CFR Part 50 when one or more of the RCS cold legs are less than or equal to 350*F.
Either PORV has adequate relieving capability to protect the RCS from overpressurization when the transient is limited to either:
(1) the start of an idle RCP with the secondary water temperature of the steam generator less than or equal to 50*F above the RCS cold leg temperatures, or (2) the maximum credible mass injection flow rate due to the startup of a single HHSI pump plus 100 gpm net charging flow, while the RCS is in a water solid condition and the RCS temperature is between 350*F and 200*F.
For RCS temperatures less than 200"F, the maximum overpressure event consists of operating a centrifugal charging pump with complete termination of letdown and a failure of the charging flow control valve to the full flow condition.
I SOUTH TEXAS - UNITS 1 & 2 B 3/4 4-14 Unit 1 - Amendment No. 4, 62 Unit 2 - Amendment No. 51
REACTOR COOLANT SYSTEM BASES LOW TEMPERATURE OVERPRESSURE PROTECTION (Continued)
The design mass input transient in MODE 4 assumes that, with failure of one PORV to open, a safety injection signal will start one High Head Safety Injection pump.
The normal charging and letdown flow paths would be isolated by a containment isolation phase "A" signal, but a Reactor Coolant Pump seal flow rate of 100 gpm would be maintained (normal seal flow is 20 gpm).
The capacity of each PORV is sufficient to discharge the combined High Head Safety injection and Reactor Coolant Pump seal flow rate at RCS pressure below the present maximum allowable PORV setpoint pressure for 200*F.
In MODE 5, the mass input transient assumes the operation of one Centrifugal Charging Pump (CCP) with letdown isolated and the charging flow control valve full open.
In each case the letdown is isolated allowing only the path through the RCP seals with a maximum CCP flow of 100 gpm. Whether one or both CCPs are lined up to the RCP seal flow path, the credible flow through the RCP seals can only be 20 gpm with letdown isolated unless a seal failure occurs. Therefore, by positioning the charging isolation valve closed during a pump testing or switching process, assurance is provided that a mass additional pressure transient, which exceeds the relief capacity of a single PORV, will not occur.
The Maximum Allowed PORV Setpoint for the Cold Overpressure Mitigation System (COMS) is derived by analysis which models the performance of the COMS assuming various mass input and heat input transients. Operation with a PORV Setpoint less than or equal to the maximum Setpoint ensures that Appendix G criteria will not be violated with consideration for a maximum pressure SOUTH TEXAS - UNITS 1 & 2 8 3/4 4-14a Unit 1 - Amendment No. 62 Unit 2 - Amendment No. 51