Text

Amends 167 & 157 to Licenses DPR-77 & DPR-79,respectively, Incorporating Changes Necessary for Expansion of Spent Fuel Pool Storage Capacity to 2091 Fuel Assemblies
	ML20087G358
Person / Time
Site:	Sequoyah
Issue date:	04/28/1993
From:	Hebdon F; Office of Nuclear Reactor Regulation
To:	;
Shared Package
ML20087G361	List: ML20087G358;
References
	NUDOCS 9504040168
	Download: ML20087G358 (26)
	v • d • e

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'h UNITED STATES E.

NUCLEAR REGULATORY COMMISSION n

5 WASHINGTON, D. C. N555 IW!iESSEE VALLEY AUTHORIT_1 DOCKET NO. 50-327 SE000YAH NUCLEAR PLANT. UNIT 1 AMENDMENT TO FACILITY OPERATING LICENSE Amendment No. 167 License No. DPR-77 1.

The Nuclear Regulatory Commission (the Commission) has found that:

A.

The application for amendment by Tennessee Valley Authority (the '

I licensee) dated March 27, 1992, which was supplemented by letters dated May ll, May 28, September 8, and October 8,1992; February 18-and April 1,1993, 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, the provisions of the Act, and the rules and regulations of the Commission; C.

There is reasonable assurance (1) 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 amendment will not be inimical ** 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.

9504040168 930428 PDR ADOCK 05000327 p

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,1 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. DPR-77 is hereby amended to read as follows:

'(2) Technical Specifications The Technical Specifications contained in Appendices A and B, as revised through Amendment No. 167, are hereby incorporated in the license. The licensee shall operate the facility in accordance with.

the Technical Specifications.

3.

This license amendment is effective as of its date of issuance.

It will be implemented when the proper plant conditions can be established that will accommodate the corresponding modifications. The staff requests that the licensee inform the Commission by letter when implementation has been completed.

FOR THE NUCLEAR REGULATORY COMISSION h

Frederick J. H edon, Director Project Directorate II-4 Division of Reactor Projects - 1/II Office of Nuclear Reactor Regulation

Attachment:

Changes to the Technical Specifications Date of Issuance: April 28, 1993 a

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i ATTACHMENT TO LICENSE AMENDMENT NO. 167 FACILITY OPERATING LICENSE NO. DPR-77 I

DOCKET NO. 50-327 i

Revise the Appendix A Technical Specifications by removing the pages identified below and inserting the enclosed pages. The revised pages are identified by the. captioned amendment number and contain marginal lines indicating.the area of change.

REMOVE INSERI I

3/4 9-la 3/4 9-la 3/4 9-7 3/4 9-7 3/4 9-7a 3/4 9-7a.

B3/4 9-2 B3/4 9-2 5-5 5-5 5-Sa 5-5b 5-5c 5-5d 5-Se l

9 l

t i

3/4.9 REFUELING OPERAIIONS l

SURVEILLANCE RE0VIREMENTS (Continued) 4.9.1.3 One of the following valve combinations shall be verified closed under administrative control at least once per 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months s:

Combination A Combination B Combination C Combination D a.

1-81-536 a.

1-81-536 b.

1-62-922 b.

1-62-907 b.

1-62-907 c.

1-62-916 c.

1-62-914 c.

1-62-914 d.

1-62-933 d.

1-62-940 d.

1-62-921 d.

1-62-921 e.

1-62-696 e.

1-62-933 e.

1-62-940 f.

1-62-929 f.

1-62-929 g.

1-62-932 q.

1-62-932 h.

1-FCV-62-128 h.

1-62-696 1.

1-FCV-62-128 4.9.1.4 The boron concentration in the spent fuel pool shall be determined by chemical analysis to be greater than or equal to 2,000 parts per million (ppm) at least once per 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months during fuel movement and until the configuration of the assemblies in.the storage racks is verified to comply with the criticality loading criteria specified in Design Feature 5.6.1.1.c and 5.6.1.1.d.

4.9.1.5 The boron concentration in the cask loading area of the cask pit shall be determined by chemical analysis to be greater than or equal to 2000 parts per million (ppm) at least once per 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months during fuel movement in that area and until the assemblies in that storage rack are verified to comply with the criticality loading criteria specified in Design Feature 5.6.1.1.e.

SEQUOYAH - UNIT 1 3/4 9-la Amendment No. 12, 144, 167

s REFUELING OPERATIONS l

3/4.9.7 CRANE TRAVEL - SPENT FUEL PIT AREA LIMITING CONDITION FOR OPERATION l

3.9.7 Loads traveling over fuel assemblies in the spent fuel pit area shall be

]

restricted as follows:

j a.

Spent fuel storage pool:

Loads in excess of 2100 pounds

shall be prohibited from travel over fuel assemblies in the spent fuel storage pool.

b.

Cask loading area of the cask pit:

1.

Loads which meet the weight, cross-sectional impact area, and allowable travel height criteria of Figure 3.9-1 may be carried over fuel assemblies stored in the cask loading area of the cask pit if the impact shield is in place over the cask loading area.

2.

Loads which do not meet the weight, cross-sectional impact area, and allowable travel height criteria of Figure 3.9-1 shall be prohibited from travel over the cask loading area of the cask i

pit when fuel is stored in it.

j APPLICABILITY: With fuel assemblies in the spent fuel storage pool or in the 4

cask loading area of the cask pit.

ACTION:

With the requirements of the above specification not satisfied, place the crane load in a safe condition. The provisions of Specification 3.0.3 are not applicable.

SURVEILLANCE REQUIREMENTS 4.9.7.1 Crane interlocks and physical stops which prevent crane hook travel over the storage pool shall be demonstrated OPERABLE within 7 days prior to crane use and at least once per 7 days thereafter during crane operation.

4.9.7.2 When fuel is stored in the cask pit area, verify administrative.

requirements concerning the impect shield are met prior to moving loads in excess of 2100 pounds across the cask pit area.

The spent fuel pool transfer canal gate and the spent fuel pool divider gate may travel over fuel assemblies in the spent fuel pool.

SEQUOYAH - UNIT 1 3/4 9-7 Amendment No. 91, 167

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FIGURE 3.9-1 RELATIONSHIP BETWEEN LOAD. ALLOWABLE NEIGNT AND INFACT AREA FOR OBJECTS TO BE CARRIED OVER TNE IPIFACT SHIELD e

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s REFUELING OPERATIONS BASES 3/4.9.6 MANIPULATOR CRANE The OPERABILITY requirements.for the manipulator cranes ensure that:

1) manipulator cranes will be used.for movement of drive rods and fuel assen-blies, 2) each crane has sufficient load capacity to lift a drive rod or fuel assembly, and 3) the core internals and pressure vessel are protected from excessive lifting force in the event they are inadvertently engaged during lifting operations.

3/4.9.7 CRANE TRAVEL - SPENT FUEL PIT AREA The restriction on movement of loads in excess of the nominal weight of a fuel and control rod assembly and associated handling tool over other fuel assemblies in the storage pool ensures that in the event this load is dropped:

1) the activity release will be limited to that contained in a single fuel assembly, and 2) any possible distortion of fuel in the storage racks will not result in a critical array. This assumption is consistent with the activity release assumed in the accident analyses. Assurance against load drops over fuel stored in the cask loading area of the cask pit is achieved by observance of the calculated load criteria which will prevent penetration of the impact shield in the event of a load drop.

3/4.9.8 RESIDUAL HEAT REMOVAL AND COOLANT CIRCULATION The requirement that at least one residual heat removal (RHR) loop be in operation ensures that; 1) sufficient cooling capacity is available to remove decay heat and maintain the water in the reactor pressure vessel below 140*F as required during the REFUELING MODE, and 2) sufficient coolant circulation is

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maintained through the reactor core to minimize the effects of a boron dilution incident and prevent boron stratification. The minimum required flow rate of 2000 ~gpm ensures decay heat removal, minimizes the probability of losing an RHR pump by air-entrainment from pump vortexing, and minimizes the potential for valve damage due to cavitation or chatter. Losing an RHR pump is a particular concern during reduced RCS inventory operation. The 2000 gpm value is limited by the potential for cavitation in the control valve and chattering in the 10-inch check valve.

1 The requirement to have two RHR loops OPERABLE when there is less than 23 feet of water above the reactor pressure vessel flange ensures that a single failure of the operating RHR loop will not result in a complete loss of resid-1 ual heat removal capability. With the reactor vessel head removed and 23 feet-of water above the reactor pressure vessel flange, a large heat sink is avail-able for core cooling. Thus, in the event of a failure of the operating RHR loop, adequate time is provided to initiate emergency procedures to cool the Core.

r SEQUOYAH - UNIT 1 B 3/4 9-2 Amendaent No. 134, 167 w.

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7 DESIGN FEATURES 5.6 FUEL STORAGE' CRITICALITY'- SPENT FUEL 5.6.1.1 The spent fuel storage racks are designed for fuel enriched to 5 weight' percent U-235 and shall be maintained with:

a.

A K,,, equivalent to less than 0.95 when flooded with unborated water.,

b.

A nominal 8.972 inch center-to-center distance between fuel assemblies placed in the storage racks.

1 c.

A three region arrangement in the spent fuel storage pool with the I

following definitions:

1.

Region 1 is designed to accommodate new fuel with a maximum enrichment of 4.95 i 0.05 wt% U-235, or spent fuel regardless of the fuel burnup.

2.

Region 2 is designed to accommodate fuel of 4.95% initial enrichment burned to at least 50 MWD /KgU (assembly average), or fuel of other enrichments with a burnup yielding an equivalent reactivity in the fuel racks. The minimum required assembly.

average burnup in, MWD /Kgu is,given by Y; when Y = -23.761.+

22.075E - 2.0165E + 0.1152E, where E is the initial enrichment in the axial zone of highest enrichment.

3.

Region 3 is designed to accommodate fuel of 4.95% initial enrichment burned to at least 41 MWD /KgU (assembly average), or l

fuel of other enrichments with a burnup yielding an equivalent reactivity in the fuel racks. The minimum required assembly averageburnupisgivenbyYp/KgU)whereY=-25.7425

+ 18.76E - 1.3933E + 0.0666E, where E is the initial enrichment in the axial zone of highest enrichment.

An empty cell is less reactive than any cell containing fuel and therefore may be used as a Region 1, Region 2, or Region 3 cell in any arrangement.

q d.

The following arrangement of regions apply in the spent fuel storage pool-1.

Region 1 fuel assemblies located along the periphery of the storage modules adjacent to the pool walls must be isolated from

For some accident conditions, the presence of dissolved boron in the pool' water may be taken into account by applying the double contingency principle which requires two unlikely, independent, concurrent events to produce a criticality accident.

i SEQUOYAH - UNIT 1 5-5 Amendment No. 13, 60, 114, 144, 167

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- 1'

- DESIGN FEATURES

' 5.6L FUEL STORAGE each other and from the inner Region 3 cells by at least one1(1)

Region 2 spent fuel assembly (i.e., fuel of 50 MWD /KgU burnup or equivalent).

2.

Region 1. fuel assemblies located along the' wide water-gaps **

between storage modules must be isolated from each other and frge the. inner Region 3 cells by at least one (1) Region 2 spent fuel assembly (i.e., fuel of 50 MWD /KgU assembly. average burnup or equivalent).

~3.

Region 1 fuel assemblies located along the narrow water-gaps **

between storage modules must be isolated from each other by at least two (2) Region 2 spent fuel assemblies and from the inner Region 3 ' cells by at least one (1) Region 2 spent fuel assembly (i.e., fuel of 50 MWD /KgU assembly average burnup or equivalent).

4.

A checkerboard pattern of fresh fuel and empty cells may be used throughout any storage module, or internal to any storage module-in lieu of Region 3 fuel as shown in Figure 5.6-2.

Figure 5.6-1 shows a typical arrangement of regions. Figure 5.6-2 illustrates internal module checkerboarding of fresh fuel with empty cells in a portion of the fuel pool.

Figure 5.6-3 illustrates the two burnup-enrichment equations (5.6.1.1.c.2 and 5.6.1.1.c.3) in graphical form.

e.

Only spent fuel meeting the Region 3 burnup requirements shall be stored in any module in the cask leading area of the cask pit.

CRITICALITY - NEW FUEL i

5.6.1.2 The new fuel pit storage racks are designed and shall be maintained with a nominal 21.0 inch center-to-center distance between new fuel assemblies-1 such that k,n will not exceed 0.98 when fuel having an enrichment of_4.5 weight percent U-235 is in place and optimum achievable moderation is assumed.

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DRAINAGE l

5.6.2 The spent fuel pit is designed and shall be maintained to prevent inadvertent draining of the pool below elevation 722 ft.

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- The nominal gap (2-1/8 inches) running in the E-W direction between the adjacent modules is referred to as the " wide gap." The N-S direction gap (1.5 inch) is referred to as the " narrow gap."

SEQUOYAH - UNIT 1 5-Sa Amendment No. 13, 60, 114, 144, 167

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o DESIGN FEATURES l

l 5.6 FUEL STORAGE CAPACITY 5.6.3 The spent fuel storage pool is designed and shall be maintained with a t

storage capacity limited to no more than 2091 fuel assemblies.

In addition, no I

l more than 225 fuel assemblies will be stored in a rack module in the cask loading area of the cask pit.

5.7 COMPONENT CYCLIC OR TRANSIENT LIMIT 5.7.1 The components identified in Table 5.7-1 are designed and shall be maintained within the cyclic or transient limits of Table 5.7-1.

i SEQUOYAH - UNIT 1 5-5b Amendment No.167

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Fuel assemblies with initial enrichment-burnup combinations in Domain I may be placed in either Region 1, 2, or 3 storage cells.

Domain II:

Fuel assemblies with initial enrichment-burnup combinations in D = in II shall be placed only in Region 1 or 3 storage cells.

Domain III:

Fuel assemblies with initial enrichment-burnup combinations in Domain III shall

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be placed only in Region 1 storage cells FIGURE 5.6-3 SEQUOYAH - UNIT 1 5-Se Amendmint 167

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UNITED STATES 8

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NUCLEAR REGULATORY COMMISSION o

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WASHINGTON, D. C. 20S55

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TENNESSEE VALLEY AUTHORITY DOCKET NO. 50-328 SE000YAH NUCLEAR PLANT.' UNIT 2 AAENDMENT TO FACILITY OPERATING LICENSE.

' Amendment No. 157 License No. DPR-79 J

1.

. The Nuclear Regulatory Commission (the Commission) has found'that:

A.

The application for amendment by Tennessee Valley Authority (the

{

licensee) dated March 27, 1992, which was supplemented by letters dated May 11, May 28, September 8 and.0ctober 8, 1992; February 18 and April 1, 1993, 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, the l

provisions of the Act, and the rules and regulations of the Commission, C.

There is reasonable assurance (1) that the' activities authorized by.

1 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 amendment will not be inimicall 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.

.. 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. DPR-79 is hereby amended to read as follows:

(2) Technical Specifications The Technical Specifications contained in Appendices A and B, as revised through Amendment No.157, are hereby incorporated in the license. The licensee shall operate the facility in accordance with the Technical Specifications.

3.

This license amendment is effective as of its date of issuance.

It will be implemented when the proper plant conditions can be established that will accommodate the corresponding modifications. The staff requests that the licensee inform the Commission by letter when implementation has been completed.

FOR THE NUCLEAR REGULATORY COMMISSION

$Mg.zC Frederick J. Hebd n, Director Project Directorate II-4 Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation

Attachment:

Changes to the Technical Specifications Date of Issuance: April 28, 1993

ATTACHMENT TO LICENSE AMENDMENT NO.157 FACILITY OPERATING LICENSE NO. DPR-79 DOCKET NO. 50-328 Revise the Appendix A Technical Specifications by removing the pages identified below and inserting the enclosed pages. The revised pages are identified by the captioned amendment number and contain marginal lines indicating the area of change.

REMOVE INSERT 3/4 9-2 3/4 9-2 3/4 9-8 3/4 9-8 3/4 9-8a 3/4 9-8a B3/4 9-2 B3/4 9-2 5-5 5-5 5-Sa 5-5b 5-Sc 5-5d 5-Se i

l j

i REFUELING OPERATIONS SURVEILLANCE RE0VIREMENTS (Continued) 4.9.1.2 The boron concentration of the reactor coolant system and the refuel-l ing canal shall be determined by chemical analysis at least once per 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months .

4.9.1.3 One of the following valve combinations shall be verified closed under l

administrative control at least once per 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months s:

Combination A Combination B Combination C Combination D a.

2-81-536 a.

2-81-536 b.

2-62-922 b.

2-62-907 b.

2-62-907 c.

2-62-916 c.

2-62-914 c.

2-62-914 d.

2-62-933

_d.

2-62-940 d.

2-62-921 d.

2-62-921 e.

2-62-696 e.

2-62-933 e.

2-62-940 f.

2-62-929 f.

2-62-929 g.

2-62-932 g.

2-62-932 h.

2-FCV-62-128 h.

2-62-696 1.

2-FCV-62-128 4.9.1.4 The boron concentration in the spent fuel pool shall be determined by chemical analysis to be greater than or equal to 2000 ppm at least once per 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months during fuel movement and until the configuration of the assemblies in the storage racks is verified to comply with the criticality loading criteria specified in Design Feature 5.6.1.1.c and 5.6.1.1.d.

4.9.1.5 The boron concentration in the cask loading area of the cask pit shall be determined by chemical analysis to be greater than or equal to 2000 parts per million (ppm) at least once per 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months during fuel movement in that area and until the assemblies in that storage rack are verified to comply with the i

criticality loading criteria specified in Design Feature 5.6.1.1.e.

1 SEQUOYAH - UNIT 2 3/4 9-2 Amendment No. 125, 157

REFUELING OPERATIONS 3/4.9.7 CRANE TRAVEL - SPENT FUEL PIT AREA

)

LIMITING CONDITION FOR OPERATION 3.9.7 Loads traveling over fuel assemblies in the spent fuel pit area shall be restricted as follows:

a.

Spent fuel storage pool:

Loads in excess of 2100 pounds

shall be prohibited from travel over fuel assemblies in the spent fuel storage pool.

b.

Cask loading area of the cask pit:

1.

Loads which meet the weight, cross-sectional impact area, and allowable travel height criteria of Figure 3.9-1 may be carried.

l over fuel assemblies stored in the cask loading area of the cask pit if the impact shield is in place over the cask loading area.

2.

Loads which do not meet the weight, cross-sectional impact area, I

and allowable travel height criteria of Figure 3.9-1 shall be prohibited from travel over the cask loading area of the cask pit when fuel is stored in it.

APPLICABILITY: With fuel assemblies in the spent fuel storage pool or in the l

cask loading area of the cask pit.

ACTION:

With the requirements of the above specification not satisfied, place the crane load in a safe condition. The provisions of Specification 3.0.3 are not applicable.

SURVEILLANCE RE0VIREMENTS 4.9.7.1 Crane interlocks and physical stops which prevent crane hook' travel over the storage pool shall be demonstrated OPERABLE within 7 days prior to crane use and at least once per 7 days thereafter during crane operation.

4.9.7.2 When fuel is stored in the cask pit area, verify administrative requirements concerning the impact shield are met prior to moving loads in excess of 2100 pounds across the cask pit area.

The spent fuel pool transfer canal gate and the spent fuel pool divider gate may travel over fuel assemblies in the spent fuel pool.

SEQUOYAH - UNIT 2 3/4 9-8 Amendment No. 81, 157

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FIGURR 3.9-1 RELATIONSHIP BETWEEN LOAD. ALLONABLE HEIGHT AND IMPACT I

AREA FOR OBJECTS TO BE CARRIED OVER THE IMPACT SHIELD

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l REFUELING OPERATIONS BASES

'i 3/4.9.6 MANIPULATOR CRANE The OPERABILITY requirements for the manipulator' cranes ensure that:

1) manipulator cranes will be used for movement of drive rods and fuel assem-blies, 2) each crane has sufficient load capacity to lift a drive rod or fuel assembly, and 3) the core internals and pressure vessel are protected from excessive lifting force in the event they are inadvertently engaged during lifting operations.

3/4.9.7 CRANE TRAVEL - SPENT FUEL PIT AREA The restriction on movement of loads in excess of the nominal weight of a fuel and control rod assembly and associated handling tool over other fuel assemblies in the storage pool ensures that in the event this load is dropped i

1) the activity release will be limited to that contained in a single fuel i

assembly, and 2) any possible distortion of. fuel in the storage. racks will not result in a critical array. This assumption is consistent with the activity release assumed in the accident analyses. Assurance against load drops over l

fuel stored in the cask loading area of the cask pit is achieved by observance of the calculated load criteria which will prevent penetration of the impact shield in the event of a load drop.

3/4.9.8 RESIDUAL HEAT REMOVAL AND COOLANT CIRCULATION The requirement that at least one residual heat removal (RHR) loop be in operation ensures that; 1) sufficient cooling capacity is available to remove decay heat and maintain the water in the reactor pressure vessel below 140*F i

as required during the REFUELING MODE, and 2) sufficient coolant circulation is maintained thru the reactor core to minimize the effects of a boron dilution i

incident and prevent boron stratification. The minimum required flow rate of 2000 gpm ensures decay heat removal, minimizes the probability of losing an RHR pump by air-entrainment from pump vortexing, and minimizes the potential for valve damage due to cavitation or chatter.

Losing an RHR pump is a particular concern during reduced RCS inventory operation. The 2000 gpm value is limited by the potential for cavitation in the control valve and chattering in the 10-inch check valve, j

l The requirement to have two RHR loops OPERABLE when there is less than 23 feet of water above the reactor pressure vessel flange ensures that a single failure of the operating RHR loop will not result in a complete loss of residual heat removal capability. With the reactor vessel head removed and 23 feet of water above the reactor pressure vessel flange, a large heat sink is available for core cooling. Thus, in the event of a failure of the operat-ing RHR loop, adequate time is provided to initiate emergency procedures to cool the core.

SEQUOYAH - UNIT 2 B 3/4 9-2 Amendment No. 121, 157 J

e DESIGN FEATURES 5.6 FUEL STORAGE CRITICALITY - SPENT FUEL 5.6.1.1 The spent fuel storage racks are designed for fuel enriched to 5 weight percent U-235 and shall be maintained with.

a.

AK equivalent to less than 0.95 when flooded with unborated wat,,*

er.

b.

A nominal 8.972 inch center-to-center distance between fuel assemblies placed in' the storage racks.

]

c.

A three region arrangement in the spent fuel storage pool with the i

following definitions:

l.

Region 1 is designed to accommodate new fuel with a maximum enrichment of 4.95 i 0.05 wt% U-235, or spent fuel regardless of the fuel burnup.

2.

Region 2 is designed to accommodate fuel of 4.95% initial enrichment burned to at least 50 WD/KgU (assembly average), or fuel of other enrichments with a burnup yielding an equivalent i

reactivity in the fuel racks. The minimum required assembly average burnup'in WD/KgU is given by Y; when Y - -23.761 +

8 3

22.075E - 2.0165E + 0.1152E, where E is the initial enrichment in the axial zone of highest enrichment.

3.

Region 3 is designed to accommodate fuel of 4.95% initial enrichment burned to at least 41 WD/KgU (assembly average), or i

fuel of other enrichments with a burnup yielding an equivalent reactivity in the fuel racks. The minimum required assembly average burnup if +given by Y(WD/Kgu) where Y = -25.7425 +

3 18.76E - 1.3933E 0.0666E, where E is the initial enrichment in the axial zone of highest enrichment.

An empty cell is less reactive than any cell containing fuel and therefore may be used as a Region 1, Region 2, or Region 3 cell in any arrangement.

i d.

The following arrangement. of regions apply in the spent fuel storage pool:

1.

Region I fuel assemblies located along the periphery of the storage modules adjacent to the pool walls must be isolated from

For some accident conditions, the presence of dissolved boron in the pool water may be taken into account by applying the double contingency principle which requires two unlikely, independent, concurrent events to produce a criticality accident.

SEQUOYAH - UNIT 2 5-5 Amendment No. 4, 52, 125, 157 l

' DESIGN FEATURES 5.6 FUEL STORAGE each other and from the inner Region 3 cells by at least one (1)

Region 2 spent fuel assembly (i.e., fuel of 50 MWD /KgU burnup or equivalent).

2.

Region I fuel assemblies located along the wide watar-gaps **

between storage modules must be isolated from each other and from the inner Region 3 cells by at least one (1) Region 2 spent fuel assembly (i.e., fuel of 50 MWD /KgU assembly average burnup-orequivalent).

j, 3.

Region I fuel assemblies located along the narrow water-gaps **

between storage modules must be isolated from each other by at least two (2) Region 2 spent fuel assemblies and from the inner Region 3 cells by at least one (1) Region 2 spent fuel assembly (i.e., fuel of 50 MWD /KgU assembly average burnup or equivalent).

I 4.

A checkerboard pattern of fresh fuel and empty cells may be used throughout any storage module, or internal to any storage module in lieu of Region 3 fuel as shown in Figure 5.6-2.

t Figure 5.6-1 shows a typical arrangement of regions.

Figure 5.6-2 illustrates internal module checkerboarding of fresh fuel with empty cells in a portion of the fuel pool. Figure 5.6-3 illustrates-the two burnup-enrichment equations (5.6.1.1.c.2 and 5.6.1.1.c.3) in graphical form.

l e.

Only spent fuel meeting the Region 3 burnup requirements shall be stored in any module in the cask loading area of the cask pit.

CRITICALITY - NEW FUEL 5.6.1.2 The new fuel pit storage racks are designed and shall be maintained with a nominal 21.0 inch center-to-center distance between new fuel assemblies -

such that k will not exceed 0.98 when fuel having an enrichment of 4.5 weight i

percentU-23y5 is in place and optimum achievable moderation is assumed.-

l DRAINAGE 5.6.2 The spent fuel storage pool is designed and shall be maintained to prevent inadvertent draining of the pool below elevation 722 ft.

i j

l

- The nominal gap (2-1/8 inches) running in the E-W direction between the adjacent modules is referred to as the " wide gap." The N-S direction gap (1.5 inch) is referred to as the " narrow gap."

SEQUOYAH - UNIT 2 5-Sa Amendment No. 4, 52, 125, 157

DESIGN FEATURES 5.6 FUEL STORAGE CAPACITY 5.6.3 The spent fuel storage pool is designed and shall be maintained with a storage capacity limited to no more than 2091 fuel assemblies.

In addition, no more than 225 fuel assemblies will be stored in a rack module in the cask loading area of the cask pit.

5.7 COMPONENT CYCLIC OR TRANSIENT LIMIT 5.7.1 The components identified in Table 5.7-1 are designed and shall be maintained within the cyclic or transient limits of Table 5.7-1.

l SEQUOYAH - UNIT 2 5-5b Amendment No.157

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Domain II:

Fuel assemblies with initial enrichment-burnup combinations in Domain II shall be placed only in Region 1 or 3 storage cells.

I 1

Domain III:

Fuel assemblies with initial-enrichment-burnup combinations in Domain III shall be placed only in Region 1 storage cells 1

FIGURE 5.6-3 SEQUOYAH - UNIT 2 5-Se Amendment 157

.. -

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