ML023230321

Technical Specification Change 02-06, Increased Condensate Storage Tank (CST) Minimum Volume.

ML023230321
Person / Time
Site:	Sequoyah
Issue date:	11/15/2002
From:	Salas P Tennessee Valley Authority
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
TVA-SQN-TS-02-06
Download: ML023230321 (113)

Text

November 15, 2002 TVA-SQN-TS-02-06 10 CFR 50.90 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555 Gentlemen:

In the Matter of ) Docket Nos. 50-327 Tennessee Valley Authority ) 50-328 SEQUOYAH NUCLEAR PLANT (SQN) - UNITS 1 AND 2 - TECHNICAL SPECIFICATION (TS) CHANGE 02-06, INCREASED CONDENSATE STOARAGE TANK (CST) MINIMUM VOLUME Pursuant to 10 CFR 50.90, TVA is submitting a request for a TS change (TSC 02-06) to licenses DPR-77 and DPR-79 for Units 1 and 2. The proposed change will revise TS 3.7.1.3, Condensate Storage Water, Limiting Condition for Operation for SQN Units 1 and 2 by increasing the required minimum amount of stored water from 190,000 gallons to 240,000 gallons. TVA is requesting this change to support the replacement steam generator requirements. Greater steam generator structural mass and upgraded regulatory standards were used to reevaluate the minimum CST volume. This request is similar to the approved license amendment request by South Carolina Electric & Gas Companys (SCE&G)

Virgil C. Summer Nuclear Station, Amendment Number 145 issued July 7, 2000.

TVA has determined that there are no significant hazards considerations associated with the proposed change and that the TS change qualifies for

Enclosure 1 TENNESSEE VALLEY AUTHORITY SEQUOYAH PLANT (SQN)

UNITS 1 AND 2 TVA Evaluation of the Proposed Change

1. DESCRIPTION This letter is a request to amend Operating License(s) DPR-77 and DPR-79 for SQN Units 1 and 2. The proposed change would revise the Limiting Condition of Operation (LCO) of Technical Specification (TS) 3.7.1.3, Condensate Storage Water (CST), to require an additional inventory of water storage, as the preferred coolant source during credible design accidents. In addition, the associated TS Bases will be modified for clarity. This proposed change will address the requirement of additional coolant water for plant transients resulting in the need for auxiliary feedwater after replacement steam generators installation. contains the proposed TS Bases revision associated with the proposed revised LCO.

2. PROPOSED CHANGE This amendment request proposes to revise SQNs TS 3.7.1.3, Condensate Storage Water, for Units 1 and 2 by increasing the minimum amount of stored water.

Specifically, the minimum water volume value of 190,000 gallons will be replaced by 240,000 gallons such that the revised LCO will state:

The condensate storage tank system (CST) shall be OPERABLE with a contained water volume of a least 240,000 gallons of water.

The associated TS Bases 3/4.7.1.3, Condensate Storage Tank, also includes a proposed revision. This proposed revision will clarify the basis for the minimum amount of water. This revision, as can be seen in Enclosure 3, will include the statement:

and to subsequently reduce the reactor coolant system temperature to HOT SHUTDOWN conditions in 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> at which time the heat removal load is transferred to the residual heat removal system.

In summary, the minimum condensate storage tank water volume of 190,000 gallons to be maintained during applicable modes will be increased to 240,000 gallons. This change reflects the necessary minimum amount of feedwater, with an additional 12,000 gallon margin, to assist in steam generator recovery of Unit 1 by removing primary stored and residual core energy for such events as loss of normal feedwater supply or secondary system pipe rupture. This proposed change is conservatively requested for both units since the Unit 1 CST is inter-connected to the Unit 2 CST.

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3. BACKGROUND Each of SQNs CSTs consist of a non-seismic qualified carbon steel tank with capacity of 385,000 gallons. The CSTs are connected to the condenser hotwell and hotwell pumps discharge for the addition and dumping of water, respectively, to maintain water inventory in the secondary system. Storage tank level is maintained by makeup from the water treatment plant. Each tank is equipped with an electronic level indicator which provides continuous tank level indication and provides a signal in the main control room for annunciation of abnormal tank levels. In addition, each tank is provided with a local level indicator. The current minimum water amount of 190,000 gallons in each tank is reserved for the auxiliary feedwater (AFW) Systems by means of an administrative limit based upon indicated level set points.

A CST is the preferred and primary source of clean water for the AFW. An alternate unlimited source of cooling water is supplied by the seismic Category 1 essential raw cooling water (ERCW) system. The ERCW supply can be remote-manually aligned based on CST level or automatically on a two-out-of-three low-pressure signal in the condensate suction line. In addition, the fire protection system can be aligned to supply feedwater in the event of a flood above plant grade. (Reference 1)

TS 3.7.1.3 currently requires the CST of both Unit 1 and 2 be operable by maintaining a minimum water volume of 190,000 gallons. This minimum volume of water in the CST is specified, as stated in TS Bases 3.7.1.3, to ensure sufficient water is available to the AFW system to maintain the reactor coolant system (RCS) at hot standby for two hours.

(Reference 2)

Sequoyah is currently working towards replacement of its Unit 1 steam generators in the Spring of 2003. The design of the replacement steam generator provides additional structural mass over the original steam generator and consequently an increase in stored energy content. TVA has chosen to reevaluate the minimum CST volume using a newer standard for decay heat generation and associated conservative input parameters. These changes have resulted in an increase in the minimum CST inventory. In addition to this proposed TS LCO change, a TS Bases change is proposed to clarify that the CST minimum volume includes capacity to reduce the RCS temperature to hot shutdown conditions within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> of reactor trip.

There is precedence for allowing an increase in the minimum required water volume in the CST as a result of replacement steam generators. The South Carolina Electric &

Gas Company (SCE&G) operating license for the Virgil C. Summer Nuclear Station, has been amended to allow an increase in the required minimum water volume of the CST as a result of replacement steam generators, uprate, and recalculated value of the unusable volume of the CST. This amendment, Number 145, was issued on July 7, 2000.

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4. TECHNICAL ANALYSIS The minimum required volume of water in the CST, as specified by LCO 3.7.1.3, is being changed from 190,000 gallons to 240,000 gallons. This change is based on the increased requirements created by installing replacement steam generators on Unit 1, newer standard for modeling decay heat generation (Reference 3), and revised input assumptions for the calculation to determine the minimum water volume necessary during plant transients.

The previous required inventory of 190,000 gallons was originally based on a very conservative decay heat model and the time from a reactor trip to placing the residual heat removal (RHR) system in service (References 4 and 5). The core decay heat model for the original CST inventory determination was based on the conservative Westinghouse Electric Company decay heat model (circa 1970), a precursor to ANS 5.1-1971. To determine the new CST inventory requirements, the core heat production associated with decay heat is based on the 1994 ANS standard with B&W heavy actinide contribution.

Several of the original assumptions were incorporated into the calculation. These assumption are as follows:

1. Following reactor trip, no reactor coolant pumps are operating,

2. Following the reactor trip, the RCS temperature is reduced to 350 degrees Fahrenheit (°F) over a period of 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />, at which time the heat removal load is transferred to the RHR system, (NOTE: The sequence and length of time at hot standby and for cooldown do not affect the water requirement; rather, the time from reactor trip to RHR operation determines the water requirement.)

3. All feedwater is assumed to be delivered to the steam generator for heat removal by evaporation and released through the main steam safety valves. Release of feedwater other than through the main steam safety valves, such as spillage due to a feedline break, is not considered.

The following assumptions have been changed from the original CST inventory calculations to allow greater operation freedom and support emergency response guidelines:.

1. The original AFW temperature assumption of 100°F used by Westinghouse Electric Company in 1971 was increased by 20 degrees for an AFW temperature input value of 120°F, E1-3

2. The original AFW requirement did not include the quantity of water needed to refill the steam generators; whereas this calculation considered steam generator refill to the normal zero load level, and

3. The assumption of the reactor operating at 102% of the power level (corresponding to the turbine-generator unit maximum calculated heat balance) was changed to 100.7%. This is the result of the recent installation of a new main feedwater leading edge flow measurement system which provided a 1.3% reduction in the calorimetric uncertainty of the secondary side power measurement.

The calculation to determined the minimum volume requirements of the CST is included in Enclosure 4.

The proposed increase in the minimum water volume of the CST ensures that a sufficient quantity of the preferred source of clean feedwater is available for use during plant transients that require use of the AFW system. However, the CSTs are not seismically qualified and NRC Branch Technical Position (RSB 5-1) Section G, Auxiliary Feedwater Supply, states:

The Seismic Category 1 water supply for the auxiliary feedwater system for a PWR (pressure water reactor) shall have sufficient inventory to permit operation at hot shutdown for at least 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />, followed by cooldown to the conditions permitting operation of the residual heat removal (RHR) system. The inventory needed for cooldown shall be based on the longest cooldown time needed with either only onsite or only offsite power available with an assumed single failure.

The AFW system is backed by an unlimited supply of water from the ERCW system, which is designed for seismic conditions (i.e., seismic Category 1) and meets single failure requirements (References 6 and 7). Hence, Sequoyah meets RSB 5-1 Section G.

In summary, the proposed revision to TS 3.7.1.3, Condensate Storage Tank, minimum water volume from 190,000 gallons to 240,000 gallons reflects the additional amount of water necessary to cool the replacement steam generators of Unit 1 with the revised assumptions. TVA has proposed that both the Unit 1 and 2 TSs be revised because Unit 1 and Unit 2 CSTs are inter-connected. The proposed minimum water volume increase is the result of calculations performed by Framatome ANP. These calculations took into consideration the original calculations basis for the LCO for TS 3.7.1.3; the increase in structural mass of the new steam generators; a more limiting AFW temperature of 120°F, refill to the normal steam generator zero load level, and the recent upgrade in rated thermal power. Since the calculations were performed with a more limiting replacement steam generator for Unit 1, they are also applicable to the original Unit 2 steam generators.

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5. REGULATORY SAFETY ANALYSIS This license amendment request proposes to revise SQNs TS 3.7.1.3, Condensate Storage Water, for Units 1 and 2 by increasing the minimum amount of stored water.

Specifically, the minimum water volume value of 190,000 gallons will be replaced by 240,000 gallons such that the revised LCO will state:

The condensate storage tank system (CST) shall be OPERABLE with a contained water volume of a least 240,000 gallons of water.

The associated TS Bases 3/4.7.1.3, Condensate Storage Tank, also includes a proposed revision. This proposed revision will clarify the base for the minimum amount of water. This revision, as can be seen in Enclosure 3, will include the statement:

and to subsequently reduce the reactor coolant system temperature to HOT SHUTDOWN conditions within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> at which time the heat removal load is transferred to the residual heat removal system.

In summary, the minimum CST water volume of 190,000 gallons to be maintained during applicable modes will be increased to 240,000 gallons. This change reflects the necessary minimum amount of feedwater, with administrative margin, to assist in steam generator recovery of Unit 1 by removing primary stored and residual core energy for such events as loss of normal feedwater supply or secondary system pipe rupture.

Because Unit 1 CST is inter-connected to the Unit 2 CST, this proposed change is conservatively requested for both units.

5.1 No Significant Hazards Consideration TVA has evaluated whether or not a significant hazards consideration is involved with the proposed amendment(s) by focusing on the three standards set forth in 10 CFR 50.92, Issuance of amendment, as discussed below:

1. Does the proposed change involve a significant increase in the probability or consequences of an accident previously evaluated?

Response: No.

The proposed change does not change the physical design and construction of the condensate storage tank (CST). The purpose of the increased water volume is to ensure that the required volume of water, preserved by the technical specification (TS), is sufficient to meet Sequoyah Nuclear Plant (SQN) Licensing and Design Basis after installation of the replacement steam generators. The change in the administratively controlled inventory of the CST will not increase the probability of an accident. Therefore, the proposed change does not involve a significant increase in the probability of consequences of an accident previously evaluated.

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2. Does the proposed change create the possibility of a new or different kind of accident from any accident previously evaluated?

Response: No.

This change increases the minimum required volume of water in the CST, thus ensuring that the auxiliary feedwater (AFW) system can perform its required safety function, using a preferred water source for plant transient mitigation.

The maximum and normal water levels in the CST are not being changed.

Additionally, increasing the minimum water volume requirement will not initiate any accident. Therefore, the proposed change does not create the possibility of a new or different kind of accident from any previously evaluated.

3. Does the proposed change involve a significant reduction in a margin of safety?

Response: No.

This change does not reduce any margin associated with the CST inventory available to AFW. The requirement for sufficient CST volume to maintain hot standby and subsequent cooldown to hot shutdown continues to be met by the minimum volume increase. Additionally, the essential raw cooling water (ERCW) system still provides the long-term supply of safety grade cooling water to the AFW in the event that all inventory of the CST is lost. Therefore, the proposed change does not involve a significant reduction in a margin of safety.

Based on the above, TVA concludes that the proposed amendment(s) present no significant hazards consideration under the standards set forth in 10 CFR 50.92 ( c), and accordingly, a finding of no significant hazards consideration is justified.

5.2 Applicable Regulatory Requirements/Criteria The regulatory basis for TS 3.7.1.3, Condensate Storage Tank, is to provides a safety grade source of water to the steam generators for removing decay and sensible heat from the reactor coolant system (RCS). Sequoyah CST provides the primary and preferred source of AFW during plant transients. The ERCW is the backup safety-related system which meets the basis for providing a safety grade source of water.

10 CFR Part 50 General Design Criteria (GDC) 2, Design bases for protection against natural phenomena, requires structures, systems, and components (SSCs) important to safety shall be designed to withstand the effects of natural phenomena such as earthquakes, tornadoes, hurricanes, floods, tsunami, and seiches without loss of capability to perform their safety functions.

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GDC 5, Sharing of structures, systems, and components, requires that SSCs important to safety shall not be shared among nuclear power units unless it can be shown that such sharing will not significantly impair their ability to perform their safety functions, including, in the event of an accident in one unit, an orderly shutdown and cooldown of the remaining units.

GDC 44, Cooling water, describes that a system to transfer heat from SSCs important to safety, to an ultimate heat sink shall be provided.

GDC 45, Inspection of cooling water system, defines that the cooling water system shall be designed to permit appropriate periodic inspection of important components, such as heat exchangers and piping, to assure the integrity and capability of the system.

GDC 46, Testing of cooling water system, requires that the cooling water system shall be designed to permit appropriate periodic pressure and functional testing.

Regulatory Guidance 1.29, Seismic Design Classification, describes the acceptable method for identifying and classifying those features of a light-water-cooled nuclear power plant that should be designed to withstand the effects of a Safe Shutdown Earthquake.

NRC Branch Technical Position RSB 5-1, Design Requirements of the Residual Heat Removal System, dated July 1981.

NUREG -0800, U.S. NRC Standard Review Plan, Section 9.2.6, Condensate Storage Facilities, provides guidance to the NRC staff for the review and evaluation of system design features from the CST to the connections or interfaces with other systems associated with the condensate storage facilities, which may or may not be safety related.

The CST is aligned to the AFW system as the primary and preferred source of cooling water for plant transients that result in a need for AFW. NUREG-0800, Standard Review Plan, Section 9.2.6, Condensate Storage Facility, provides guidelines to assure conformance with the requirements of General Design Criteria 2, 5, 44, 45, and 46. A condensate storage facility may not be safety related as in the case of Sequoyahs CST, but it is recognized that a CST may have provisions to automatically transfer to a seismic Category I source. Sequoyah conforms with these requirements.

The TSs for the CST has once been amended to extend the limiting condition for operation of the CSTs to Mode 4 when steam generators are relied upon for heat removal. In the accompanying NRC safety evaluation report (SER) it was written that following a reactor trip, decay heat is dissipated by evaporating water in the steam generator and venting the steam either to the condensers or to the E1-7

atmosphere. In such situations, steam generator water inventory must be maintained at a level sufficient to ensure adequate heat transfer and decay heat removal. The AFW system pumps deliver this emergency water supply to the steam generators. The AFW system provides emergency water to the steam generators until either normal feed water flow is established or the residual heat removal (RHR) system can assume the decay heat removal function. The primary sources of water for the AFW system pumps are the CSTs. On low suction pressure, the AFW pumps are designed to automatically swap to the ERCW.

The ERCW is a seismic Category 1 system (Reference 6). However in order to maintain our current license basis, preferred source, and an adequate amount of the primary source of cooling water, SQN has chosen to request a license amendment to increase the minimum amount of CST inventory.

In conclusion, based on the considerations discussed above, (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commissions regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.

6. ENVIRONMENTAL CONSIDERATION A review has determined that the proposed amendment would change a requirement with respect to installation or use of a facility component located within the restricted area, as defined in 10 CFR 20, or would change an inspection or surveillance requirement. However, the proposed amendment does not involve (i) a significant hazards consideration, (ii) a significant change in the types or significant increase in the amounts of any effluent that may be released offsite, or (iii) a significant increase in individual or cumulative occupational radiation exposure. Accordingly, the proposed amendment meets the eligibility criterion for categorical exclusion set forth in 10 CFR 51.22( c)(9). Therefore, pursuant to 10 CFR 50.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the proposed amendment.

7. REFERENCES

1. Sequoyah Nuclear Plant, Final Safety Analysis Report (As Updated) Revision 17, Section 10.4.7.2.2, System Description

2. Sequoyah Nuclear Plant, Technical Specification Bases 3/4.7.1.3, Condensate Storage Tank

3. American Nuclear Society Document ANSI/ANS-5.1-1994, American National Standard for Removing Decay Heat Power in Light Water Reactors, dated August 23, 1994 E1-8

4. Letter to TVA from Westinghouse Electric Corporation, AFW Flows and Condensate Storage Tank Volume, dated May 23, 1993 (B38930607811)

5. Letter to TVA from Westinghouse Electric Corporation, Required Auxiliary Feedwater Storage Quantity, dated November 20, 1981 (811218F0714)

6. Sequoyah Nuclear Plant, Final Safety Analysis Report (As Updated) Revision 17, Section 9.2.2, Essential Raw Cooling Water (ERCW)

7. NUREG 0011 - Safety Evaluation Report for Sequoyah Nuclear Plant dated March 1979, Section 10.4.2, Auxiliary Feedwater System E1-9

ENCLOSURE 2 TENNESSEE VALLEY AUTHORITY SEQUOYAH PLANT (SQN)

UNITS 1 AND 2 Proposed Technical Specification Changes (mark-up)

I. AFFECTED PAGE LIST Unit 1 3/4 7-7 Unit 2 3/4 7-7 II. MARKED PAGES See attached.

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PLANT SYSTEMS CONDENSATE STORAGE TANK LIMITING CONDITION FOR OPERATION 3.7.1.3 A condensate storage tank system (CST) shall be OPERABLE with a contained water volume of at least 190,000 gallons of water.

240,000 APPLICABILITY: MODES 1, 2 and 3, MODE 4 when steam generator is relied upon for heat removal.

ACTION:

With the condensate storage tank system inoperable, within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> either:

a. Restore the CST to OPERABLE status or be in at least HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in HOT SHUTDOWN within the following 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> without reliance on steam generator for heat removal, or

b. Verify by administrative means OPERABILITY of the Essential Raw Cooling Water System as a backup supply to the auxiliary feedwater pumps* and restore the condensate storage tank to OPERABLE status within 7 days or be in at least HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in HOT SHUTDOWN within the following 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> without reliance on steam generator for heat removal.

SURVEILLANCE REQUIREMENTS 4.7.1.3.1 The condensate storage tank system shall be demonstrated OPERABLE at least once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> by verifying the contained water volume is within its limits when the tank is the supply source for the auxiliary feedwater pumps.

• OPERABILITY shall be verified once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> following initial verification.

November 19, 1998 SEQUOYAH - UNIT 1 3/4 7-7 Amendment No. 238 E2-2

PLANT SYSTEMS CONDENSATE STORAGE TANK LIMITING CONDITION FOR OPERATION 3.7.1.3 The condensate storage tank system (CST) shall be OPERABLE with a contained water volume of at least 190,000 gallons of water.

240,000 APPLICABILITY: MODES 1, 2 and 3, MODE 4 when steam generator is relied upon for heat removal.

ACTION:

With the condensate storage tank system inoperable, within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> either:

a. Restore the CST to OPERABLE status or be in at least HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in HOT SHUTDOWN within the following 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> without reliance on steam generator for heat removal, or

b. Verify by administrative means OPERABILITY of the Essential Raw Cooling Water System as a backup supply to the auxiliary feedwater pumps* and restore the condensate storage tank to OPERABLE status within 7 days or be in at least HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in HOT SHUTDOWN within the following 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> without reliance on steam generator for heat removal.

SURVEILLANCE REQUIREMENTS 4.7.1.3.1 The condensate storage tank system shall be demonstrated OPERABLE at least once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> by verifying the contained water volume is within its limits when the system is the supply source for the auxiliary feedwater pumps.

• OPERABILITY shall be verified once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> following initial verification.

November 19, 1998 SEQUOYAH - UNIT 2 3/4 7-7 Amendment No. 228 E2-3

ENCLOSURE 3 TENNESSEE VALLEY AUTHORITY SEQUOYAH PLANT (SQN)

UNITS 1 AND 2 Changes to Technical Specifications Bases Pages I. AFFECTED PAGE LIST Unit 1 B3/4 7-2b Unit 2 B3/4 7-2b II. MARKED PAGES See attached.

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PLANT SYSTEMS BASES which are designated as Train A, receive A-train air, and provide flow to the same steam generators that are supplied by the B-train motor-driven auxiliary feedwater pump. The remaining two LCVs are designated as Train B, receive B-train air, and provide flow to the same steam generators that are supplied by the A-train motor-driven pump. This design provides the required redundancy to ensure that at least two steam generators receive the necessary flow assuming any single failure. It can be seen from the description provided above that the loss of a single train of air (A or B) will not prevent the auxiliary feedwater system from performing its intended safety function and is no more severe than the loss of a single auxiliary feedwater pump. Therefore, the loss of a single train of auxiliary air only affects the capability of a single motor-driven auxiliary feedwater pump because the turbine-driven pump is still capable of providing flow to two steam generators that are separate from the other motor-driven pump.

Two redundant steam sources are required to be operable to ensure that at least one source is available for the steam-driven auxiliary feedwater (AFW) pump operation following a feedwater or main steam line break. This requirement ensures that the plant remains within its design basis (i.e., AFW to two intact steam generators) given the event of a loss of the No. 1 steam generator because of a main steam line or feedwater line break and a single failure of the B-train motor driven AFW pump. The two redundant sources must be aligned such that No. 1 steam generator source is open and operable and the No. 4 steam generator source is closed and operable.

For instances where one train of emergency raw cooling water (ERCW) is declared inoperable in accordance with technical specifications, the AFW turbine-driven pump is considered operable since it is supplied by both trains of ERCW. Similarly, the AFW turbine-driven pump is considered operable when one train of the AFW loss of power start function is declared inoperable in accordance with Technical Specifications because both 6.9 kilovolt shutdown board logic trains supply this function. This position is consistent with American National Standards Institute/ANS 58.9 requirements (i.e., postulation of the failure of the opposite train is not required while relying on the TS limiting condition for operation).

3/4.7.1.3 CONDENSATE STORAGE TANK The OPERABILITY of the condensate storage tank with the minimum water volume ensures that sufficient water is available to maintain the RCS at HOT STANDBY conditions for 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> with steam discharge to the atmosphere concurrent with total loss of off-site power. The contained water volume limit includes an allowance for water not useable because of tank discharge line location or other physical characteristics.

SENTENCE INSERT and to subsequently reduce the reactor coolant system temperature to HOT SHUTDOWN conditions in 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> at which time the heat removal load is transferred to the residual heat removal system August 22, 1995 SEQUOYAH - UNIT 1 B 3/4 7-2b Amendment No. 115, 155, 182, 188 196, 207 E3-2

PLANT SYSTEMS BASES train air, and provide flow to the same steam generators that are supplied by the A-train motor-driven pump. This design provides the required redundancy to ensure that at least two steam generators receive the necessary flow assuming any single failure. It can be seen from the description provided above that the loss of a single train of air (A or B) will not prevent the auxiliary feedwater system from performing its intended safety function and is no more severe than the loss of a single auxiliary feedwater pump.

Therefore, the loss of a single train of auxiliary air only affects the capability of a single motor-driven auxiliary feedwater pump because the turbine-driven pump is still capable of providing flow to two steam generators that are separate from the other motor-driven pump.

Two redundant steam sources are required to be operable to ensure that at least one source is available for the steam-driven auxiliary feedwater (AFW) pump operation following a feedwater or main steam line break. This requirement ensures that the plant remains within its design basis (i.e., AFW to two intact steam generators) given the event of a loss of the No. 1 steam generator because of a main steam line or feedwater line break and a single failure of the B-train motor driven AFW pump. The two redundant sources must be aligned such that No. 1 steam generator source is open and operable and the No. 4 steam generator source is closed and operable.

For instances where one train of emergency raw cooling water (ERCW) is declared inoperable in accordance with technical specifications, the AFW turbine-driven pump is considered operable since it is supplied by both trains of ERCW. Similarly, the AFW turbine-driven pump is considered operable when one train of the AFW loss of power start function is declared inoperable in accordance with technical specifications because both 6.9 kilovolt shutdown board logic trains supply this function. Similarly, the AFW turbine-driven pump is considered operable when one train of the AFW loss of power start function is declared inoperable in accordance with Technical Specifications because both 6.9 kilovolt shutdown board logic trains supply this function. This position is consistent with American National Standards Institute/ANS 58.9 requirements (i.e., postulation of the failure of the opposite train is not required while relying on the TS limiting condition for operation).

3/4.7.1.3 CONDENSATE STORAGE TANK The OPERABILITY of the condensate storage tank with the minimum water volume ensures that sufficient water is available to maintain the RCS at HOT STANDBY conditions for 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> with steam discharge to the atmosphere concurrent with total loss of off-site power. The contained water volume limit includes an allowance for water not usable because of tank discharge line location or other physical characteristics.

SENTENCE INSERT and to subsequently reduce the reactor coolant system temperature to HOT SHUTDOWN conditions in 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> at which time the heat removal load is transferred to the residual heat removal system August 22, 1995 SEQUOYAH - UNIT 2 B 3/4 7-2b Amendment No. 105, 174, 180, 187, 197 E3-3

ENCLOSURE 4 TENNESSEE VALLEY AUTHORITY SEQUOYAH PLANT (SQN)

UNITS 1 AND 2 Framatome ANP, SQN Condensate Volume Requirement Verification E4-1