ML20069Q411

Proposed Tech Specs Increasing Initial Fuel Enrichment Limit from Current Maximum 4.0 Weight % to 4.75 Weight % & Establish New Loading Patterns for New & Irradiated Fuel in SPF

ML20069Q411
Person / Time
Site:	McGuire, Mcguire
Issue date:	06/13/1994
From:	DUKE POWER CO.
To:
Shared Package
ML20069Q405	List: ML20069Q402 ML20069Q411
References
NUDOCS 9406270398
Download: ML20069Q411 (101)

Text

l INDEX LIMITING CONDITIONS FOR OPERATION AND SURVEILLANCE REQUIREMENTS SECTION

_PAGE 3/4.9.8 RESIDUAL HEAT REMOVAL AND COOLANT CIRCULATION High Water Level.... ........ . .... .. ................. 3/4 9-10 Low Water Level.........

3/4.9.9

.......... ..................... 3/4 9-11 WATER LEVEL - REACTOR VESSEL... ..... ................... 3/4 9-12

, 3/4.9.10

1. WATER LEVEL - STORAGE P00L. ............................. 3/4 9-13 3/4.9.11 FUEL HANDLING VENTILATION EXHAUST SYSTEM................. 3/4 9-14 h ,k !

4'3/T9'T270Et--S-TORAGE '

__S. PENT FUEL P00 L. . . . . . . . . . . . . . . . m.. 5/4 9-16 TABLE 3.9-1 MINIMUM BURNT!P_vs I-NI+T4f"ERIEHMENW2 S-T0RA C ..................................... M R 3/4.10 SPECIAL TEST EXCEPTIONS 3/4.10.1 SHUTDOWN MARGIN..........................................

3/4.10.2 GROUP HEIGHT, INSERTION, AND POWER DISTRIBUTION LIMITS... 3/4 10-1 3/4.10.3 PHYSICS 3/4 10-2 3/4.10.4 TESTS............................................ 3/4 10-3 REACTOR COOLANT LOOPS ................................... 3/4 10-4 3/4.10.5 POSITION INDICATION SYSTEM -

SHUTD0WN.................... 3/4 10-5 3/4.11 RADI0 ACTIVE EFFLUENTS y

3/4 11.1 LIQUID EFFLUENTS Liquid Holdup Tanks....................................... 3/4 11-7 3/4 11.2 GASE0US EFFLUENTS Explosive Gas Mixture..................................... 3/4 11-16 Gas Storage Tanks......................................... 3/4 11-17 3/4,9.I2 S pe cd 9 ucA f'oo ( 'Ty;<o n Conc adrnTto n , . 3/.4 # 1 - t /o 3/ 4 . 9 . l 3 See n t bt Aw-M y Mcrea s c - - . . - . - - . 3/4 P 17 Tcdo\c. '$. 9 - I MJear.s.>r<, QM 'y(c g %u mp W2 raes . D d44 *t b n 6 nu M be b.Gic,6 ~1.

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PDR ADOCK 05000269

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INDEX LIMITING CONDITIONS FOR OPERATION AND SURVEILLANCE REQUIREMENTS L

SECTION PAGE 3/4.9.8 RESIDUAL HEAT REMOVAL AND COOLANT CIRCULATION High Water Level......................................... 3/4 9-10 Low Water Leve1.......................................... 3/4 9-11 3/4.9.9 WATER LEVEL - REACTOR VESSEL...... ...................... 3/4 9-12

'O 4 3/4.9.10 WATER LEVEL - STORAGE P00L............................... 3/4 9-13 p:

3/4.9.11 FUEL HANDLING VENTILATION EXHAUSTSYSTEM................. 3/4 9-14 d D 4 2 12 -FUEL SIQRAGE - SPENT FUEL P00L.............. ..

. . . ---3/4'JT6 TABLE 3.9-1 MINIMUM NTTiiu.7NRIGi

_ ST0 RAGE. . . . . . . . . . . . . .....................

. . . . . . . . . . . MENTJ R REGION .7 2

3/4.10 SPECIAL TEST EXCEPTIONS 3/4.10.1 SHUTDOWN MARGIN.......................................... 3/4 10-1 3/4.10.2 GROUP HEIGHT, INSERTION, AND POWER DISTRIBUTION LIMITS... 3/4 10-2 3/4.10.3 PHYSICS TESTS............................................ 3/4 10-3 3/4.10.4 REACTOR COOLANT LOOPS ................................... 3/4 10-4 3/4.10.5 POSITION INDICATION SYSTEM - SHUTD0WN.................... 3/4 10-5 3/4.11 RADI0 ACTIVE EFFLUENTS g 3/4 11.1 LIQUID EFFLUENTS Liquid Holdup Tanks....................................... 3/4 11-7 3/4 11.2 GASEQUS EFFLUENTS Explosive Gas Mixture..................................... 3/4 11-16 Gas Storage Tanks......................................... 3/4 11-17 c_oerh n ved bm por ous p q e_

T& 39-5 Minb >~ QM%O91 ' "Pbbos #" '

pm g n 2. m de Ant;cui --- 3/q 9 - 2.3 3 q vve , 3. 9- t P g u M > m A. f q L m d t<v) Pc d % n f o e '

Cc :ch t c4ccd @" yon ~L Si # 7 ' ' ' ~ ^ ' ' 3/tI 9 - 2 9 fux3.q z byn:d^2og & 9 Lcm 3m f d as %r fcWrictcd Re cpon 'L Mows;c . - - - -

!'49-25

~Qtc 3 vve.11 - 3 McGUIRE - O .c]ckeRc UNITS v.%

1 anf2 ne,<3. 2 od ed fe'qwn XV 2-- S LOnc4im%Mee

" % d m yen .ent No Am q _. g' 128907 (Unit 1) l Amendment No.110 (Unit 2)

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' ',' ' REFUELING OPERATIONS; [ ,ffQ, l ,

' W Q 'l .j jiy NO3/43.12~ FUEL-STORAGE-SPNfhU 3 STOR5GEi0dL@Nk Y 0  :

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LlHITING CONDITION FOR OPERATION: > *

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3. . Fuel is to be stored in' the p st racje' pool"wittE: i a.

.. . . .c.s . ' J.M he boron concentration >inithejspent:fuelipool. maintained at gre

.. - ,...j y ,

equal to 20r0 ppm; and m

b. Sto\ rage in Region'2 restrkted'to' irradiated fuel which has decayed 3M ,] P.

16 dayhand one of the following: t leas $ $. . ,

l (f / Fl --

1) fue\ l which has been qualified in accordance with Table 3. -1; or .Agg .

2) Fuel whic.Nt has been qualified by means of an analysis sing NRC o/ approved;.,

methodolog(Ato assure with~a 95 percent probability t a 95 percent confidence lhel that k,,, is no greater than 0.95 ' icluding all uncertainties: r 3) s . :n ,

Unqualified fu' ells red:in'a* checkerboard co iguration. -In:the event s s :cm -

one row;betw n. normal , storage slocations'WA.1

.i checkerboa rd . storage %s lused ,'tj ons

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'will s vacantf.N '

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1. '_ i and'che.ckbrboardStoraa ilo.ca x: 4 WT .' 36% %m s

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E APPI7' ABILITY:

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' Ouring storage of fuelthein)j , t dM4g8 %

' spent fuelgoot" 7'

ET ' ' ' '

.,y a ACTION: f., ' [Ib '

,. J ~ , - +

Suspend all actions ' involving 2t,he l f fuel in the spentLfuel, pool [3 t

a. movement , c  ;

it is determined a fuel assembly has' been piaced in the incorrect 'tili Region:u$1f!,

n - 9

^ such time as the correct'stpfageilocation is de, term & :.d. . Hove.the assemblyito.'VlEe '"

I its correct location befo 5 resumption of any other fuel movement.

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b. Suspend all actions i olving the movement ofltfue\ the spent fuel pool,1f n f.

it is determined th ool boron concentration is less than 2000, ppm untilx;% j l such time as the ba on concentration is increased to 2 ppm or greater.

c. The provisions f Specification' 3.0.3 are not applicable. '

4 '$

SURVEILLANCE REQU_IRJ1iENTS 4

/

/

4.9.12a. Veri (y ali fuel assemblies to be placed in Region 2 of the spent fuel ol are.

within the enrichment and burnup limits of Table 3.91 or that k,,, s 0.9hby

,r11ecking the assemblies' design and burnup documentation or the assemblies 5

/ qualifying analysis documentation respectively.

/

/b. Verify at least once per 31 days that the spent fuel pool boron concentration \

, is greater than 2000 ppm.

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McGUIRE UNIT 1 3/4 9 16 Amendment No.138 (Unit 1)  !

Amendment No.120 (Unit 2) l j

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. UNil 2 ONLY j l REFUEL.ING OPERAT10f6 1 3/4.9.12 FUEL STORAGE - SPENT FUEL STORAGE POOL 1.1111 G.CONDITIONFOROPERATIO1 3.9.12 Fue is to be stored in the spent storage pool with:

a. The ron concentration in the spent fuel pool maintained at greater than o I equal 2175 ppm; and l l

b. Storage i Region 2 restricted to irradiated fuel which has decayed atyleast 16 days and ne of the following: .

1) fuel which ias been qualified in accordance with Table 3.9-1 or

2) Fuel which ha been qualified by means of an analysis using NRC approved ,

methodology toconfidence level iat k,,, is no (sure withthan greater a 950.95 percent probability including all at a'95 percent uncertainties: or /

3) Unqualified fuel store in a checkerboard configuration. In the event  !

checkerboard storage is sed, one row between pormal storage locations and checkerboard storage cations will be vacant. '

APPLICABILITY:

/ l During storage of fuel in the spent fuel pool.

ACTION-

a. Suspend all actions involving the ement o fuel in the spent fuel pool if; it is determined a fuel assembly s been plac in the incorrect Region until such time as the correct stora ocation is det ined. Have the assembly to its correct location before re ption of any otheh fuel movement.

b. Suspend all actions involvi g the movement of fuel in he spent fuel pool if it is determined the pool oron concentration is less th n 2175 ppm, until such time as the boron ncentration is increased to 217 pm or greater.

c. The provisions of Specification 3.0.3 are not applicable, i

SURVEILLANCE REQUIREMENTS 4.9.12a. Verify al within

/

e enrichment and burnup limits of Table 3.91 or that k , s 0.95 y N

fuel assemblies to be placed in Region 2 of the spent fuel p 1 are l l

checki g the assemblies

• design and burnup documentation or the ,as,semblies  !

quali ying analysis documentation respectively.

b. fy at least once per 31 days that the spent fuel pool boron concentration is greater than 2175 ppm. (

I McGUIRE - UNIT 2 3/4 9 16a Amen'dment No.138 (Unit 1)

Amendment No.120 (Unit 2) l i

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Table 3.9-1 l l

Mi imum Burnup Versus Initial Enrichment for Region 2 Storage l l

Initial richment Assembly urnup l w/o U 35 ( /MT) i 1.4 ... ............................................ .. 0.00

1. 5 .... ..... .................................. .... 2.50 1.6 ...... ...... . .... ....................... ...... 5.00 ,

1.7 ....... .. .. ..................................... 6.65 l 1.8 ......... ............................... ......... s.30

' 9 ...... ...

.. ........................... ........... 9.95 i 2.0 ........... ........................ ............ 11.60 1 2.1 ............. ...................... ............. 13.20 l 2.2 .... ......... ................... ............... 14.60 l 2.3 .. ...... .. ... ............... ................. 16.00 2.4 ................. ............ ................... 17.40 i 2.5 .................. .......... .................... 18.80 1 2.6 ....... ............ ...... ...................... 20.20 l i

2.7 ..................... ... ........................ 21.40 l 2.8 .................................................. 22.60 2.9 ...... ............... . ......................... 23.90 l 3.0 .................... .... ........................ 25.20 3.1 ............ ... . ........ ...................... 26.60 3.2 ............................ ..................... 27.80 3.3 ............... ............. .................... 28.93 3.4 ............. ................. .................. 30.07 l 3.5 .... ...... .................... ................. 31.20 3.6 ....... . ........ ............ ............... 32.26 3.7 ........ .......................... .............. 33.32 3.8 ...... .... ........................ ............. 34.38 3.9 .... ................................ ........... 35.44 4.0 ... ................................... .......... 36.50 Amendment No. 69 (Unit 1)

McGUIRE - UNITS 1 and 2 3/4 9-17 Amendment No. 50 (Unit 2) __

4 i

REFUELING OPERATIONS 3/4.9.12 SPENT FUEL POOL BORON CONCENTRATION p 7 /L.

LIMITING CONDITION FOR OPERATION h JV 3.9.12The boron concentration in the spent fuel pool shall be within the limit specified in the COLR. (([#V APPLICABILITY: , f- j During storage of fuelin the spent fuel pool.

ACTION:

e. imniediately suspend movement of fuel assemblies in the spent fuel pool l and initiate cetion to restore the spent fuel pool boron concentration to  !

within its limit. )

l

b. The provisions of Specification 3.0.3 are not applicable.

SURVEILLANCE REQUIRF.MENTS: , j I

4.9.12 Verify at least once per 31 days that the spent fuel pool boron concentration is within its limit.

3/4.9.13 SPENT FUEL ASSEMBLY STORAGE lh (j v LIMITING CONDITION FOR OPERATION

1. u) 3/q.7.B 3.9.13 Storage of new or irradiated fuel is limited to the configurations described in

/

this specification.

a. New or irradiated fuel may be stored in Region 1 of the Spent Fuel Poolin accordance with these limits:

1) Unrestricted storage of fuel meeting the criteria of Table 3.9-1; or

2) Restricted storage in accordance with Figure 3.9-1, of fuel which does n21 meet the criteria of Table 3.9-1; or

3) Another configuration determined to be acceptable by means of an analysis to ensure that keg, is less than or equal to 0.95.

b. New or irradiated fuel which has decayed at least 16 days may be stored in Region 2 of the Spent Fuel Poolin accordance with these limits:

1) Unrestricted storage of fuel meeting the criteria of Table 3.9-3; or

2) Restricted storage in accordance with Figure 3.9-2, of fuel which meets the criteria of Table 3.9-4; or

3) Checkerboard storage in accordance with Figure 3.9-3 of fuel which does nat meet the criteria of Table 3.9-4; or

4) Another configuration determined to be acceptable by means of an analysis to ensure that k egg is less than or equal to 0.95.

APPLICABILITY:

During storage of fuelin the spent fuel pool.

ACTION:

a. Immediately initiate action to move the non complying fuel assembly to the correct location.

b. The provisions of Specification 3.0.3 are not applicable.

SURVEILLANCE REQUIREMENTS:

(fa 3h. k' 4.9.13 Prior to storing a fuel assembly in the spent fuel storage pool, verify by administrative means the initial enrichment and burnup of the fuel assembly are in accordance with Specification 3.9.13.

l i

4

Table 3.9-1 @

Minimum Qualifvina Burnuo Versus initial Enrichment N }~ h l for Unrestricted Reaion 1 Storace

/,7./

Initial Enrichment Assembly Burnup Weicht% U-235 (GWD/MTU) 4.19 (or less) 0 4.20 0.04 4.50 1.92 4.75 3.40 5 --

$ 4--

R S

" 3~~

ACCEPTABLE 5

ca

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2--

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5 jj 1 ~ UNACCEPTABLE q 0 -

l  : i 4.00 4.25 4.50 4.75 Initial Enrichment (Weight % U-235) l 1

l

l 1

Table 3.9-2 Minimum Qualifyina Burnuo Versus initial Enrichment fj'$ \

for Reaion 1 Fiiler Assemblies M'Q 3h, '

Initial Enrichment Assembly Burnup Weicht% U-235 (GWD/MTU) ,

2.92 (or less) 0  ;

3.00 1.57 3.50 13.30 4.00 18.32 4.50 23.36 4.75 25.84  :

.l 30 --  ;

y 25 -- j h

g 20 -

ACCEPTABLE I v l

$ 15 -

a i m 1

@ 10 --  !

5 UNACCEPTABLE l w

2 5- l 0  :  :

2.5 3 3.5 4 4.5 4.75 Initial Enrichment (Weight % U-235) l

Table 3.9-3, 6 Minimum Qualifyina Burnuo Versus initial Enrichment gd  ;

for Unrestricted Region 2 Storage l 3/1. 'l g l l

l Initial Enrichment Assembly Burnup l Weight % U-235 (GWD/MTU)  ;

2.00 (or less) 10.54 -

2.50 17.96 l 3.00 24.64 l 3.50 30.86 )

4.00 36.75 2 4.50 42.38  ;

4.75 45.10  ;

i 60 --  ;

y 50 " ACCEPTABLE i R  !

@ 40 --  !

S -

a.

y 30 --

c5 i j' 20 --

R UNACCEPTABLE  ;

4 102 j i

t 0  : i 2 2.5 3 3.5 4 4.5 4.75 l Initial Enrichment (Weight % U-235) ) ,

i~

I Table 3.9-4 Minimum Qualifving Burnuo Versus initial Enrichment for Restricted Region 2 Storage with Fillers g(( '

3N. 7 /3 l t

initial Enrichment Assembly Burnup l Weicht% U-235 (GWD/MTU) i 2.00 (or less) 4.22 l 2.50 10.75 l 3.00 16.80  !

3.50 22.41 .

4.00 27.92  !

4.50 33.14 {

4.75 35.65' }

i i

l 60 --  ;

l S 50 - i Ei  ;

s 4 40 - ACCEPTABLE i

$ 30 --

t ca

@ 20 -- i E I 30 10 - UNACCEPTABLE  !

l 0  :  :  :  :

)

2 2.5 3 3.5 4 4.5 4.75 Initial Enrichment (Weight % U-235) 9 l

l

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Table 3.9-5 f0 .

Minimum Qualifvina Burnuo Versus initial Enrichment g g sL ,

1 for Region 2 Fiiler Assemblies f,/3 i

Initial Enrichment Assembly Burnup  ;

Weight % U-235 (GWD/MTU) 2.00 (or less) 18.03 2.50 26.71  :

3.00 33.79 l 3.50 40.56 4.00 46.83 4.50 52.86 4.75 55.78 I i

i 60 --

ACCEPTABLE y 50 _

i se 40 -

S.

o_

E 30 -

e co

-y20 7 UNACCEPTABLE P,? 4 12 10 -

0  :  :  :  :  :

2 2.5 3 3.5 4 4.5 4.75 Initial Enrichment (Weight % U-235)

kD Fioure 3.9-1 odi Reauired 3 out of 4 Loadino Pattem ,

for Restricted Reaion 1 Storace /

s iS <

RESTRICTED ,

RESTRICTED RESTRICTED RESTRICTED FUEL FUEL FUEL FUEL

^

< s d!N m iW a

RESTRICTED FILLER RESTRICTED FILLER FUEL LOCATION FUEL LOCATION g

' ~

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RESTRICTED RESTRICTED RESTRICTED RESTRICTED FUEL FUEL FUEL FUEL

• ,x 3 ,

v RESTRICTED FILLER RESTRICTED FILLER FUEL LOCATION FUEL LOCATION Restricted Fuel: Fuel which does ng1 meet the minimum burnup requirements of Table 3.9-1. (Fuel which does meet the requirements of Table 3.9-1 may be placed in restricted fuellocations as needed)

Filler Location: Either fuel which meets the minimum burnup requirements of i Table 3.9-2, on an empty cell.

Boundary Condition: Any row bounded by a Region 1 Unrestricted Storage Area shall contain a combination of restricted fuel assemblies and filler locations arranged l such that no restricted fuel assemblies are adjacent to each other.

Example: In the figure above, row 1 or column 1 can ng.1 be adjacent to l a Region 1 Unrestricted Storage Area, but row 4 or column 4 can be.

f Fioure 3.9-2 Reauired 2 out of 4 Loadino Pattern for Restricted Reaion 2 Storace 36'[3 7

^ t '>

RESTRICTED FILLER RESTRICTED FILLER FUEL LOCATION FUEL LOCATION

ti , ls l

l

. s FILLER RESTRICTED FILLER RESTRICTED LOCATION FUEL LOCATION FUEL l em -

RESTRICTED FILLER RESTRICTED FILLER FUEL LOCATION FUEL LOCATION s

in m i M

. FALLER RESTRICTED FILLER RESTRICTED LOCATION FUEL LOCATION FUEL Restricted Fuel: Fuel which meets the minimum burnup requirements of Table 3.9-4.

Filler Location: Either fuel which meets the minimum burnup requirements of Table 3.9-5, or an empty cell.

Boundary Condition: No restrictions on boundary assemblies.

Fioure 3.9-3 g Reauired 2 out of 4 Loadino Pattern -

for Checkerboard Reaion 2 Storaoe I

yc j)g , n v: v f CHECKERBOARE EMPTY  ::HECKERBOARE EMPTY FUEL CELL FUEL CELL

,tu ,' l' - ' ?;f ,;' :

$ '7* j@g gg gg EMPTY OHECKERBOARE EMPTY  ::HECKERBOARE CELL FUEL CELL FUEL

$5 M $5N,+ ini#'

OIMI"<, Aslin'" y CHECKERBOARE EMPTY  ::HECKERBOARC EMPTY FUEL CELL FUEL CELL g ,; , ;iens

? '

BV '6 EMPTY CHECKERBOARE EMPTY  ::HECKERBOARE CELL FUEL CELL FUEL

- ' > iM sp>ly in Jg gen, d t 304n fb -

Checkerboard Fuel: Fuel which does n01 meet the minimum burnup requirements of Table 3.9-4. (Fuel which does meet the requirements of Table 3.9-4 may be placed in checkerboard fuellocations as needed)

Boundary Condition: At least two opposite sides shall be bounded by either an empty row of cells, or a spent fuel pool wall.

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3/4.9.9 and 3/4.9.10 WATER LEVEL - REACTOR VESSEL and STORAGE POOL '

The restrictions on minimum water level ensure that sufficient water depth is available to remove 99% of the assumed 101 iodine gap activity released from the rupture '

y

of an irradiated fuel assembly. The minimum water depth is consistent with the assumptions of the accident analysis. , o, m sag ~ d 4N *: i n a

3/4.9.11 FUEL HANDLING VENTILATION EXHAUST SYSTEH' '

fl **l r

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4 l s ,

The limitations on the Fuel Handling Ventilation Exhaust System ensure that all- '

I radioactive material released from an irradiated fuel assembly will be filtered throu h . , J: ,

the HEPA filters and charcoal adsorbers prior to discharge to the atmosp~herePTh,e%g$  ; ,

fare c6rists'tenttwith acity'd?as4a i

- ,11.

i, ' ' guide for surveillance testing: 9he methylh iodide'

.0PERABILITY-of the assumptions of the accident; this systemiandithelresultingiiodine4removalicbs analyses. / ANSI'N510;1975%ill sse la - f6r' the

~ b $"' $ -

a i

carbon samples have been made more restrictive than required for the assumed iodine ) <j removal in the accident analysis because the humidity to be seen by the charcoals e - we w(

adsorbers may be greater than 70% under normal operating conditions.

4

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3/4.9,12 FUEL STORAGE - SPENT FUEL STORAGE P0OL '

The requ

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• hff A ments for fuel storage in the spent fuel pool on 3.9.12 (a) and (b)? ., re ; , g i[]j*j that: (1) spent fuel pool will: remain-subtritical during fuel stor_agei?

a. uniform boron c entration'isimaintained'in the water ' volume in the s fuel';poolifor ' c(2)!a Q u reactivity control. The value of 0.95 or less for Keff which inclu all; unce'rtaintie's 9.1.2.3.1: of 'the' FSARo jl . . ly atthe95/95probabilty(iaconfidence is the acceptance criter level as r fuelistorage in'the spent fu described in Sect e

1. Table"3.9;1 is' con f ^ ' de servatively developed in acco nee with the acceptance teria and methodologyarefer

-q fy.e denced_in figurationSection in Region 5.6 of, theiTech icep~tance.

2:msets'all!the- 1/ Specification torage11n;aicheckertised f 6 8@

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6 #p. f e' N !!?the Techni cal ; Speci fi cati ons*and liWie'r1 ~' eria, referenced in:Sectjonj5(6 f DJ ,

%;Mverification throughladminist'ratipe^cbn .t' a' *semi +^ annual: basis:afteNinitial!%

't' .

2.

^ i _ l. M Q $ N g ^ a#

'The Action Statement.,a plicable

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. x 3xl:Mh. + n ,,

fuel storage in_ ,i .spentfuelspooke,nsur,esNthat: g 5 4 % c(ou)ld result /in a.criticg M 1 :the;distoftiont fectddsfr_omi spent fuelipoofuelystoragejiatte sis? t

%F U

tration isim$intaine' ~

c ar.rafdur,iristhe? movement?o f/fu Wand ((2)ltherbbhon 16e -

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spent fuel. pool. 2000ippm~during?allyactions A gf M9GR ' ' . . J ' involvin , vesentlof;fdel h,, ".Ip i h W[

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&,4... -s- 4 W Q- 4 ka ance Requir. 7 nmte$bleit'o7fMygf ' neM .,NA.% ,

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i ementsfapplV storage 11n the1spentvfu nsu 4.Q"RTheSur.vthat'

' ~ .' 1). fuel storedliniRegion 2 ' meets'the "1"ichment and ,

1. burnu

' cm ej ' pj0.953acceptaneeter,ite avo' 1 is'70 sing the ron

. W nn.p{c6ncerit'rdtibrjfisenHef2000 wqrgrq g y;

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3/4.9 9 and 3/4.9.10 WATER LEVEL - REACTOR VESSEL and STORAGE POOL lhe restrictions on minimum water level ensure that sufficient water depth is available to remove 99% of the assumed 10% iodine gap activity released from the rupture  ;

of an irradiated fuel assembly. The minimum water depth is consistent with the assumptions of the accident analysis. .

3/4.9.11 FUEL HANDLING VENTILATION EXHAUST SYSTEM The limitations on the Fuel Handling Ventilation Exhaust System ensure that all '

radioactive material released from an irradiated fuel assembly will be filtered through the HEPA filters and charcoal adsorbers prior to discharge to the atmosphere. The OPERABILITY of this system and the resulting iodine removal capacity are consistent with the assumptions of the accident analyses. ANSI N5101975 will be used as a procedural '

guide for surveillance testing. The methyl iodide penetration test criteria for the carbon samples have been made more restrictive than required for the assumed iodine removal in the accident analysis because the humidity to be seen by the charcoal adsorbers may be greater than 70% under normal operating conditions.

l 3/4.9.12 FUEL STORAGE SPENT FUEL STORAGE POOL The repents for fuel storage in the spent fuel pool on 3.9.12 (a) and (b) ensu that: (1) thegpent fuel pool will remain subcritical during fuel storage: and a JJ d uniform boron con ntration is maintained in the water volume in the spent f reactivity control, at the 95/95 probabili e gonfidence value of 0.95 or less for Keff which includes pool for uncertainties pp ,

level as described in Section 9 ,

is the acceptance criteria foc fuel storage in the spent fuel po . 3.1 of the FSAR '[

Table 3.9 1 is con-(-  !

servatively developed in accorhnqe with-the acceptance crit ' and methodology refer- -;

enced in Section 5.6 of the TechnicM Specifications. St ge.in a checkerboard con- Ig figuration in Region 2 meets all the acceptance crite i the Technical Specifications and is verifiBd na referenced in Section 5.6 of 1 annual basis after initial M i  !

verification through administrative controls. & aF SoU'(y The Action Statement applicable to fu torage in the ent fuel pool ensures that:

(1) the spent fuel pool is protected' rom distortion in thbf g 7' g

could result in a critical array 1uring the movement of fuel:%uelndstorage tration is maintained at 21Wppm during all actions involving movement of fuel in the spent fuel pool.

(2) the boronpattern that concen-FM rgOg The SurveillancpRequirements applicable to fuel storage in the spent fuel po konsure that:

or the (1) fueT stored in Region 2 meets the enrichment and burnup limits of Tab 1R.9-1 (2),tt oron ,s 0.95 acceptance concentration meetscriteriathe 2175ofppm anlimit.

analysis using NRC approved methodology; an l

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NcGUIRE - UNIT 2 8 3/4 9-3a Am06dm"ebt'T6.'138 (UnYFi)' .

Amendment No.120 (Unit 2)

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BASES 3/4.9.12 and 3/4.9.13 SPENT FUEL POOL BORON CONCENTRATION and SPENT FUEL ASSEMBLY STORAGE The requirements for spent fuel pool boron concentration specified in Specification 3.9.12 ensure that a minimum boron concentration is maintained in the pool. The requirements for spent fuel assembly storage specified in Specification 3.9.13 ensure that the pool remains suberitical. The water in the spent fuel storage pool normally contains soluble boron, which results in large suberiticality margins under actual operating conditions. However, the NRC guic'elines based upon the accident condition in which all soluble poison is assumed to have been lost, specify that the limiting ok nof 0.95 be evaluated in the absence of soluble boron. Hence the design of the spent fuel storage racks is based on the use of unborated water, which maintains each region in a subcritical condition during normal operation with the spent fuel pool fully loaced. The double contingency principle discussed in ANSI N-16.1-1975 and the April 1978 NRC letter (Ref. 4) allows credit for soluble boron under other abnormal or accident conditions, since only a single accident need be considered at one time. For example, the most severe accident scenario is associated with the movement of fuel from Region 1 to Region 2, and accidental misloading of a fuel assembly in Region 1 or Region 2.

This could increase the reactivity of the spent fuel pool. To mitigate these postulated criticality related accidents, boron is dissolved in the pool water.

Specification 3.9.13.a.3 and 3.9.13.b.4 allow for specific criticality analysis for configurations other than those explicitly defined in Specification 3.9.13. These analyses would require using NRC approved methodology to ensure that ko n s 0.95 with a 95 percent probability at a 95 percent confidence level as described in Section 9.1 of the FSAR.

In verifying the design criteria of ken s 0.95, the criticality analysis assumed the most conservative conditions, i.e. fuel of the maximum permissible reactivity for a given configuration. Cince the data presented in Specification 3.9.13.a and 3.9.13.b represents the maximum reactivity requirements for acceptable storage, substitutions of less reactive components would also meet the ko n s 0.95 criteria. Hence, any non-fuel component may be placed in a designated empty cell location. Likewise, an empty cell, ,

or a non-fuel component may be substituted for any designated fuel assembly location. ]

These, or other substitutions which will decrease the reactivity of a particular storage cell will only decrease the overall reactivity of the spent fuel storage pool.

If both restricted and unrestricted storage is used in Region 1, an additional criteria has ,

been imposed to ensure that the boundary row between these two configurations would j not locally increase the reactivity above the required limit. Likewise if checkerboard l storage is used in Region 2, an additional restr;ction has been imposed on the boundaries of the checkerboard storage region to ensure that the reactivity would not increase above the required limit. No other restrictions on region interfaces are necessary. l l

For storage in Region 2 requiring loading pattern restrictions, (per Specifications 3.9.13.b.2 or 3.9.13.b.3) fuel may be stored in either the " cell" or "non-cell" locations.

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" Cell" locations are the areas inside the fabricated storage cells and "non-cell" locations are the storage locations created by arranging the fabricated storage cells in a checkerboard configuration. Hence the "non-cell" locations are the areas defined by the outside walls of the 4 adjacent " cell" locations.

The action statement applicable to fuel storage ;n the spent fuel pool requires that action must be taken to preclude the occurrence of an accident or to mitigate the consequences of an accident in progress. This is most efficiently achieved by immediately suspending the movement of fuel assemblies. Prior to the resumption cf fuel movement, the requirements of the LCOs must be met. This requires restoring the soluble boron concentration and the correct fuel storage configuration to within the corresponding limits. This does not preclude movement of a fuel assembly to a safe position. l The surveillance requirements ensure that the requirements of the two LCOs P.re satisfied, namely boron concentration and fuel placement. The boron concentration in the spent fuel pool is verified to be greater than or equal to the minimum limit. The fuel assemblies are verified to meet the subcriticality requirement by meeting either the initial enrichment and burnup requirements of Table 3.9-1 through 3.9-5, or by using NRC approved methodology to ensure that ek n s 0.95. By meeting either of these requirements, the analyzed accidents are fully addressed.

The fuel storage requirements and restrictions discussed here and applied in section 3.9.13 are based on a maximum allowable fuel enrichment of 4.75 weight % U-235.

The enrichments listed in Tables 3.9-1 through 3.9-5 are nominal enrichments and include uncertainties to account for the tolerance on the as built enrichment. Hence the as built enrichments may exceed the enrichments listed in the tables by up to 0.05 weight % U-235. Qualifying burnups for enrichments not listed in the tables may be linearly interpolated between the enrichments provided. This is because the reactivity of an assembly varies linearly for small ranges of enrichment.

REFERENCES

1. " Regulatory Guide 1.13: Spent Fuel Storage Facility Design Basis", U.S. Nuclear Regulatory Commission, Office of Standards Development, Revision 1, December 1976.

2 " Design Objectives for Light Water Reactor Spent Fuel Storage Facilities at Nuclear Power Stations", American Nuclear Society, ANSI N210-1976/ANS-57.2, April 1976.

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3. FSAR, Section 9.1. i

4. Double contingency principle of ANSI N16.1-1975, as specifed in the April 14,1978 NRC letter (Section 1.2) and implied in the proposed revision to Regulatory Guide 1.13 (Section 1.4, Appendix A).

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OESIGN FEATURES 5.4 REACTOR COOLANT SYSTEM DESIGN PRESSURE AND TEMPERATURE 5.4.1 The Reactor Coolant System is designed and shall be maintained:

a. In accordance with the Code requirements specified in Section 5.2 of the FSAR, with allowance for normal degradation pursuant to the applicable Surveillance Requirements,

b. For a pressure of 2485 psig, and

c. For a temperature of 650 F, except for the prassurizer which is 680 F.

VOLUME 5.4.2 The total water and steam volume of the Reactor Coolant System is 12,040 + 100 cubic feet at a nominal T f 525 F.

avg 5.5 METEOROLOGICAL TOWEP. LOCATION 5.5.1 The meteorological tower shall be located as shown on Figure 5.1-1.

5.6 FUEL STORAGE

_C__RITICALITY

5. . The new and spent fuel storage racks are designed and shall be maintal ith:

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a. Ak eq 1ent to less than or equal to unb8f$tedwater, ich includes a co when flooded with yd ative allowance for uncertainties as desc - in on 9.1.2.3.1 of the FSAR, and Ygud

b. A nominal 21-inch cen o-c istance between fuel assemblies /Ib Wg placed in the n el storage vau , and M

c. A nomi .4-inch and 9.125-inch center-t - er distance between 5- b' assemblies placed in Region 1 and Region 2 sto racks, - '

respectively, in the spent fuel stora p pool.

DRAINAGE N

5.6.2 The spent fuel storage pool is designed and shall be maintained to prevent inadvertent draining of the pool below elevation 745 ft. 7 in.

CAPACITY 5.6.3 The spent fuel storage pool is designed and shall be maintained with a storage capacity limited to no more than 1463 fuel assemblies (286 spaces in Region 1 and 1177 spaces in Region 2) having an initial enrichment less than or equal to 4.0 weight percent U-235.

i Amendment No.16 (Unit 2) 1 McGUIRE - UNITS 1 and 2 5-7 Amendment No. 35 (Unit 1) l l

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P$( yn Section 5.0 DESIGN FEATURES 8.b',

5.6 Fuel Storaae CRITICALITY l 5.6.1 a. The spent fuel storage racks are designed and shall be maintairied with k gg e

10.95 if fully flooded with unborated water as described in Section 9.1 of the FSAR: and

b. The new fuel storage racks are designed and shall be maintained with ke,,  ;

10.95 if fully flooded with unborated water; and ke r,10.98 if moderated  !

by aqueous foam as described in Section 9.1 of the FSAR.

DRAINAGE 5.6.2 The spent fuel storage poolis designed and shall be maintained to prevent  ;

inadvertent draining of the pool below elevation 745 ft. 7 in. )

CAPACITY ,

i 5.6.3 The spent fuel storage poolis designed and shall be maintained with a storage capacity limited to no more than 1463 fuel assemblies (286 spaces in Region 1 and 1177 spaces in Region 2).

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l ATTACHMENT ll NO SIGNIFICANT HAZARDS ANALYSIS Duke Power Company has reviewed the proposed changes utilizing the criteria specified in 10CFR50.92 and has determined that the proposed changes do not involve a l Significant Hazards Consideration pursuant thereto, for the reasons discussed below.

1. The proposed changes do not involve a significant increase in the probability or consequences of an accident previously evaluated. l l

There is no increase in the probability or consequences of an accident in the new fuel i vault since the only credible accidents for this area are criticality accidents and it has j been shown that calculated, worst case Keff for this area is 5 0.95 under all conditions.

There is no increase in the probability of a fuel drop accident in the Spent Fuel Storage Pool since the mass of an assembly will not be affected by the increase in fuel I enrichment. The likelihood of other accidents, previously evaluated and described in j Section 9.1.2 of the FSAR, is also not affected by the proposed changes. In fact, it could l be postulated that since the increase in fuel enrichment will allow for extended fuel cycle s, there will be a decrease in fuel movement and the probability of an accident may likewise be decreased. There is also no increase in the consequences of a fuel drop accident in the Spent Fuel Pool since the fission product inventory of individual fuel assemblies will not change significantly as a result of increased initial enrichment. In addition, no change to safety related systems is being made. Therefore, the consequences of a fuel rupture accident remain unchanged. Also, it has been shown that keff, is 5 0.95, under all conditions therefore, the consequences of a criticality accident remain unchanged as well.

2. The proposed changes do not create the possibility of a new or different kind of accident from any accident previously evaluated.

The proposed changes do not create the possibility of a new or different kind of accident sir'ce fuel handling accidents (fuel drop and misplacement) are not new or different kinds of accidents. Fuel handling accidents are already discussed in the FSAR for fuel with enrichments up to 4.1 weight %. As described in Section VI.9 of Attachment IV, additional analyses have been performed for fuel with enrichment up to 4.75 weight E Worst case misloading accidents associated with the new loading pattems were evaluated. For all possible misloading accidents the negative reactivity provided by soluble boron maintains keff 5 0.95.

3. The proposed changes do not involve a significant reduction in the margin of safety.

The proposed change does not involve a significant reduction in the margin of safety since, in all cases, a keff 5 0.95 is being maintained. Criticality analyses have been performed which show that the new fuel storage vault will remain subcritical under a

variety of moderation conditions, from fully flooded to optimum moderation. As discussed 9bove, the Spent Fuel Pool will remain sufficiently suberitical during any fuel misplacement accident.

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r ATTACHMENT 111 ENVIRONMENTAL IMPACT ANALYSIS Pursuant to 10CFR51.22 (b), an evaluation of the proposed amendments has been performed to determine whether or not it meets the criteria for categorical exclusion set forth in 10CFR51.22 (c)9 of the regulations. The proposed amendment does involve change in the use of facility components located within the restricted area as defined in 10CFR20, and changes some surveillance requirements however, the proposed o amendmen does notinvolve:

1) A sicaificant hazards consideration. ,

As discussed in Attachment 11 of this submittal, the proposed amendments do not involve i an unresolved safety question since the changes do not; 1) Increase the probability or consequences of an accident previously evaluated,2) Create a new or different kind of accident than one previously evaluated, or 3) Involve a reduction in the margin of safety.

2) A significant change in the types or significant increase in the amounts of any effluents that may be released offsite.

An increase in the fuel enrichment limit or storage configuration would not change the types of effluents created since the use of that materialis not being changed. The amounts of effluents to be released offsite also, would not be changed since, the ,

inventory of fission products contributing to offsite dose would not be increa. sed significantly with an increase in fuel enrichment or bumup, and the mechanisms used to control offsite releases are not being changed.

3) A significant increase in the individual or cumulative occupational radiation exposure. '

Increases in individual or cumulative occupational exposure would not be expected with this change since no safety systems, or related procedural controls associated with the  !

handling or storage of fuel are being changed. These safety controls ensure that sufficient water levelis maintained in the pool to provide adequate radiation shielding and that kerf 5 0.95 under all storage conditions.

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Attachment IV Duke Power Company l McGuire Nuclear Station Fuel Enrichment Upgrade License Amendment Reauest and  ;

Sypoorting Safety Analysis t

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l Table of Contents l

I I. Introduction II. Background Information III. Justification IV. Schedule V. General Description of Amendment Request / Submittal VI. Methodology Overview VII. General Results of Analysis VIII. Proposed Tech Spec /FSAR Modifications IX. Administrative Controls Appendix A Region Interface Restrictions $1ethodology Appendix B llurnup Credit Analysis 51ethodology & llenchmarking i

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l I INTRODUCTION This submittal represents Duke Power Company's formal request for approval of a license amendment which establishes several restricted loading patsms and associated burnup criteria for placement of new and irradiated fuel into both regions of the McGuire spent fuel storage pools. Analysis performed in support of this submittal demonstrates that the use of one or more of these configurations for storing fuel with initial enrichments of up to 4.75 weight % (nominal) U-235 will maintain sufficient criticality safety margins. This amendment will allow for maximum utilization of the fuel storage racks and will provide additional flexibility in the area of reactor core analysis and design.

Also included as part of this submittal is a detailed description of the analytical methodology used to generate the various burnup criteria discussed above. This methodology was specifically developed for spent fuel bumap credit applications and is based on the CASMO and SIMULATE computer codes. Since it has not been previously used by Duke Power Company, formal approval of this methodology is also being sought with this application.

II BACKGROUND INFORMATION The two unit McGuire Nuclear Station became fully operational in 1983. At that time the plant had a total spent fuel storage capacity of 1000 fuel assemblies utilizing a 15" center-to-center spacing between individual fuel assemblies in two independent spent fuel pools.

The McGuire Nuclear Station was initially licensed with a maximum allowable fuel enrichment of 4.0 weight % U-235 with an absolute tolerance of .05 weight %. Since each reactor core design is individually licensed this limit is specifically applicable to the new fuel storage vaults and the spent fuel storage pools.

In 1985 and 1987, the unit 2 and unit I spent fuel storage pools were respectively reracked with eight free standing modules of storage cells totaling 1463 per pool. The majority of the storage cells are closely spaced to accommodate less reactive burned assemblies whereas the remaining cells are intended for the higher reactivity of new or partially burned fuel. This 2 region concept resulted in a considerable increase in the fuel storage capacity allowing for 10 or more years of additional discharge capability for each reactor unit. The burnup requirements for the bumed fuel region (region 2) of the storage racks were defined by a single burnup versus enrichment curve. This curve is currently represented as table 3.9-1 in Technical Specification # 3/4.9.12. No increase in the maximum allowable enrichment was necessary or requested as part of the licensing approval for this rerack project.

In the 7 years since completing the rerack effort, the McGuire Station has pemianently discharged a significant inventory of ungealified fuel assemblies which are currently stored w." the required checkerboard storage configuration in the region 2 area of the spent fuel pool. Additionally, plans are underway to utilize future reload batches which incorporate fuel assemblies with enrichments in excess of the current 4.0 weight % limit. The continued generation of unqualified assemblies and the pending increase in fuel enrichments together represent the basis for this submittal.

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III JUSTIFICATION The primary reasons for this amendment request are to increase the efficiency of fuel storage cell utilization in the spent fuel pools and to provide additional flexibility to the reload design efforts at Duke.

The McGuire station is currently storing about 100 assemblies in the 50% checkerboard configuration which leaves over 100 storage cells unavailable for spent fuel storage.

Additionally, under the current reload design configuration, each unit will discharge up to an additional 15 " unqualified" assemblies per cycle which will require the same 50%

checkerboard storage configuration. The combination of the current and the projected unusable storage cells will force the McGuire nuclear station to install additional spent fuel storage capacity 2 to 3 years earlier than would otherwise be necessary with these cells being available for fuel storage.

Preliminary studies have indicated dry storage to be the most likely alternative for providing additional on-site storage capacity as the McGuire pools approach full capacity.

Based on current discharge projections, Duke will be forced to install additional capacity at McGuire by the year 2000. Experience at Duke's Oconee Nuclear Station shows that expenditures of up to $12 Million would be necessary to initiate such a facility with annual costs being in the range of $2 million. Delaying these startup and annual costs by freeing up current and projected unavailable storage cells would represent significant economic savings for Duke Power Company. Additionally, once the storage facility is operational, the ongoing generation of " unqualified" assemblies requiring 50% storage would force an accelerated annual rate of fuel movement into the storage facility, representing additional economic penalties.

From the standpoint of reload design, Duke continuously performs extensive economic sensitivity studies to evaluate variations in cycle length, reload batch size, and reload batch enrichments. Duke's ongoing goal is to develop the most efficient core designs for each operating cycle. Recent efforts in this area have indicated the desirability of a 459 EFPD cycle for both McGuire Units. Reload batches containing fuel with enrichments in the range of 4.10 to 4.75 weiglas are being evaluated for these extended cycles.

IV SCllEDULE Current plans for the earliest transition to the 459 EFPD cycle length are focusing on Unit 2, cycle 11 which is currently scheduled for a June,1996 startup. Based on a one year lead time requirement for planning, detailed design, licensing, enrichment, and fabrication of fuel batches, approval of the higher enrichment capability for the McGuire facility would be needed by June,1995 at the latest. A delayed approval of this amendment request beyond the middle of 1995 would force Duke Power to delay movement to this more economic 459 EFPD cycle length.

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l V. GENERAL DESCRIPTION OF AMENDMENT REQUEST /SUllMITTAL l

t V.I Introduction The primary purpose of this sub nittal is to demonstrate sufficient analytical justification for modifying technical specifications and FSAR sections currently applicable to new and irradiated fuel storage at the McGuire Nuclear Station (MNS). Areas proposed for modification are the limitations and restrictions associated with 1) storage of un-irradiated fuelin auxiliary building new fuel storage vaults,2) storage ofirradiated and un-irradiated fuel in the region 1 areas of both spent fuel pools, and 3) storage of irradiated and un-irradiated fuel in the region 2 areas of both spent fuel pools.

The fuel storage rack designs for the storage vaults and pools of both MNS units are identical. The spent fuel storage racks were designed and fabricated by Westinghouse and were installed in 1984 (unit 2) and 1986 (unit 1). Consequently all analytical methods and results discussed in this document are applicable to either unit as are the resulting procedural and technical specification modifications. Additionally, the most reactive of the fuel types applicable for each analyzed situation was used in developing the proposed requirements and limitations. Eventual approval of this amendment request should therefore apply to both units.

V.2 New Fuct Storage Vaults The new fuel storage vaults which are used for temporary dry storage of un-irradiated reload fuel are built on 21 inch centers and are currently licensed for maximum fuel enrichments of 4.0 weight % (nominal) U-235. To acccmmodate anticipated increases in individual and/or batch average enrichments that are likely to exceed this 4.0 weight % limit, previously approved analytical methods were used to demonstrate that fuel containing up to 4.75 weight % (nominal) U-235 can be safely stored in these fuel racks. No other restrictions beyond this enrichment limit are applicable to storage in the new fuel vaults. Discussion of the methods used to justify this increased limit can be found in section VI.5 and the resulting proposed FSAR modifications can be found in section VIII.2. No technical specifications are applicable to the new fuel storage vaults.

V.3 Spent Fuel Storage Pools - Region 1 The basic spent fuel storage pool rack arrangement for units 1 and 2 is shown in figure 5-1 on the following page. The region 1 area of the pool is highlighted and a schematic of the region I cell configuration is also provided.

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REGION 1 REGION 2

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j } 13 X 11. :- lll 15 X 14 ji

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REGION 1 CELL LAYOUT jiEll 12 X 16 jj~jji

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McGuire Fuel Pool Lavout with Reaion i Detal!

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t The region 1 area of the spent fuel pools is designed and generally reserved for temporary storage of new or partially irradiated fuel which would not qualify for storage in the region 2 area. The storage cell configuration in this region represents a less reactive array than that of region 2 (see section V.4). The stainless steel cells are spaced at 10.4 inches and utilize a .02 gm/cm2 oading l of Bm neutron absorbing material attached to the exterior cell wall wrapper plate. This region has a capacity (286 locations) which exceeds that needed to accommodate both a complete offload of the reactor core and storage of a reload fuel batch. As is the case with the new fuel vaults, the region 1 storage cells are limited analytically to fuel with a maximum initial enrichment of 4.0 weight %.

Unrestricted Storage To accommodate the projected as-built fuel enrichment increases discussed in section 111, the region 1 storage racks have been re-analyzed to allow for an increase in the maximum allowable initial enrichment of the stored fuel. This analysis allows for unrestricted storage (i.e. no limits on storage location or pattern) of new or irradiated fuel having initial enrichments up to 4.19 weight % (nominal).

Additional region 1 analysis was performed to develop burnup criteria for unrestricted storage of irradiated assemblies with initial enrichments in excess of the 4.19 weight %

limit stated above. These criteria are summarized in section VII.2. Expressed as specific burnup vs. enrichment limits, these criteria were generated utilizing reactivity equivalencing (burnup credit) techniques similar to that used in the original amendment request associated with installing these fuel storage racks. An overview of the specific methodology developed by Duke Power Company for this application is provided in section VI.6. A more detailed generic discussion of this methodology is submitted with this application as Appendix B.

New or irradiated assemblies which meet the requirements for unrestricted storage in region I will be referred to as fuel category 1A throughout this submittal. New or irradiated assemblies which do not meet the above requirements for unrestricted storage in region 1, but do require temporary region 1 placement for operational requirements or per existing technical specification #3.9.12.b, must be placed in a restricted loading pattern. Restricted storage requirements for region 1 are discussed below. Proposed technical specifications governing the requirements for region 1 storage are included in section VIII.l.

Restricted Storage In order to accommodate those assemblies (up to the proposed new fuel vault nominal limit of 4.75 weight %) which do not qualify for unrestricted region 1 storage, criticality analysis was performed to identify a critically safe yet simple loading pattern restriction.

While several configurations were considered, the loading pattern proposed utilizes very simple administrative control procedures and allows for maximum utilization of storage space in the spent fuel pools. Figure 5-2 on the following page illustrates the proposed storage restriction which limits storage of these unqualified assemblies to 3 of every 4 cells. Assemblies requiring placement into this storage configuration will be referred to as fuel category IB throughout this submittal. Also shown is the requirement that the fourth location of this pattern contain an appropriately qualified ' filler" assembly.

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' FILLER FILLER (FILLkk I EEEEEE E lFILLElf F L - FILLER , FUE . FILLER Figure 5-2 Realon 1 Restricted Storaae Loadina Pattern ,

l Discussion of the analysis which justifies the above loading pattern and the specific selection criteria for the filler assemblies is included in sections VI.6 and VII.2 respectively. Expressed as specific burnup vs. enrichment limits, these criteria were also generated using reactivity equivalencing (burnup credit) techniques and the specific methodology detailed in appendix B. Assemblies qualified for, and selected as fillers for region 1, will be referred to as fuel category 1Bf throughout this submittal. In the event )

that enough " filler" assemblies are not available for use, empty cells may be used in place i of appropriately qualified filler assemblies. 1 To preclude a fuel mis-loading accident, an appropriate quantity of these filler assemblies will be in place in an appropriate portion o' the region I storage area prior to placement of restricted / unqualified assemblies. This and other administrative controls are discussed l

further in section IX. Proposed technical specifications governing this and all other requirements for restricted region 1 storage are included in section Vill.l. A summary description of the various region 1 and region 2 fuel categories is provided below.

Fuel Category Region Fuel Category Description Loading Restriction New or Irradiated f uel qualified for unrestricted 1A 1 region 1 storage None New or irradiated fuel requinng restricted 75% with empty cells or ,

1B 1 region 1 storage filler assemblies  !

irradiated f uel qualified for use as region 1 tiller 1Bf 1 assemblies Use for region 1 fillers l Irradiated fuel qualified for unrestncted region 2 2A 2 storage None Irradiated fuel requinng restricted region 2 50% with empty cells or PB 2 storage with fillers or empty cells w/ filler assemblies irradiated fuel requinng restncted region 2 50% checkerboard with 2C 2 storage with empty cells empty cells irradiated f uel qualified for use as region 2 filler 2Bf 2 assemblies Use for region 2 filiers 5-4

V.4 Spent Fuel Storage Pools - Region 2 The basic spent fuel storage pool rack arrangement for units 1 and 2 is shown again in figure 5-3 on the following page with the region 2 area of the pool highlighted and a schematic of the region 2 cell configuration provided. The region 2 area of the spent fuel pools is designed and generally used for normal, long term storage of permanently discharged fuel that has achieved qualifying burnup levels. The storage cell configuration in this region represents a more reactive array than that of region 1. The stainless steel cells are assembled in a checkerboard pattern, producing a honeycomb structure of " cell" and "non-cell" locations as shown. This configuration has a much tighter center-to-center pitch of 9.125 inches. These cells also utilize a neutron absorbing material having a slightly lower Bm areal density (.006 gm/cm )2than that used in region 1. This region has a nominal capacity of 1177 locations. As is the case with the new fuel vaults and region 1 area, the region 2 storage cells are analytically limited to a maximum initial enrichment of 4.0 weight % (nominal) at this time.

Unrestricted Storage The region 2 area of the McGuire spent fuel pools was primarily designed / intended for unrestricted (i.e.100% loading pattern) storage of irradiated fuel which has achieved a qualifying level of burnup per the guidelines of technical specification # 3.9.12b.

Unqualified assemblies, when generated, must be stored in a restricted loading pattern.

The current technical specification and supporting analysis addresses fuel having initial enrichments up to 4.0 weight % (nominal). This licensing submittal proposes a redefined set of qualification specifications which will allow for fuel assemblies having initial enrichments up to the proposed higher nominal limits of the new fuel vault (4.75 weight %).

Reactivity equivalencing (burnup credit) techniques similar to those used to identify the existing qualification requirements for unrestricted storage in this region of the spent fuel pools are used to redefine new qualification requirements for the proposed wider range of initial enrichments.Section VI.6 discusses the analysis performed and the resulting enrichment vs. burnup storage criteria are covered in section VII.2. Proposed technical specifications governing this and all other requirements for unrestricted region 2 storage are included in section Vill.l. Assemblies qualifying for unrestricted region 2 storage will be referred to as fuel category 2A throughout this submittal.

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I REGION 1 REGION 2

} 13 X 11 ::: l 15 X-14. .

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13 X 11  ::: , l 16 X:14 - ,

REGION 2 CELL LAYOUT 12 X.16 -

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CELL NON CELL

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CELL CE_L E b

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CELL 12 X 16 :

9.125 TYP.

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Figure 5-3 McGuire Fuel Pool Lavout with Reaion 2 Detall e

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Restricted Storage Under the current technical specifications, fuel assemblies which have been sufficiently depleted are stored in the region 2 area of the fuel pool without restriction. Assemblies which do not qualify for unrestricted storage due to excessive discharge reactivity must be placed in a 50% checkerboard configuration. Vacant spaces adjacent to these assemblies are fitted with cell blocking devices to prevent inadvertent assembly insertion.

Currently, the two MNS pools have about 100 storage cells that are unusable due to these restnctions.

Based on analysis discussed in section VI.6, this document proposes a revised set of guidelines for region 2 which would be used to determine the need for restricted storage of fuel having initial enrichments up to 4.75 weight % (nominal). The analysis also demonstrates that sufficiently depleted " filler" fuel assemblies can be used in place of the empty cells currently required to maintain sub-criticality within the restricted loading pattern. This approach maximizes current and future storage ell utilization. Assemblies requinng restricted region 2 storage will be referred to as fuel category 2B throughout this submittal. The proposed loading pattern is illustrated in Figure 5-4 below:

FILLER FE FILLER FE em me E FILLER F FILLER l

FILLER FILLER F EL FILLE'R F L FILLER Figure 5-4 Region 2 Restricted Storage Loading Pattern l

The proposed guidelines for selecting the required filler assemblies for the restricted loading pattern in region 2, are very similar to those proposed for filler selection in region 1. As discussed in section VI.6, the reactivity level (burnup curve) which best l envelopes all of the current spent fuel inventory and projected future spent fuel

! discharges is used to determine a corresponding minimum reactivity requirement for the region 2 filler assemblies. This reactivity value is then translated into specific burnup vs.

enrichment requirements which become the selection criteria for the filler assemblies.

Criteria calculated for region 2 filler assemblies are provided in section Vll.2. Assemblies i

5-7

qualified and selected for use as region 2 fillers will be referred to as fuel category 2Bf throughout this submittal.

I Section Vll.2 shows that the restricted loading pattern discussed on the previous page is critically safe for equivalent enrichments below about 1.75 weighs. Recognizing the potential for discharging fuel at reactivity levels in excess of this limit, the existing provision to allow 50% storage with blocked empty cells will still be retained to accommodate such assemblies. Assemblies requiring this loading restriction will be referred to as fuel category 2C throughout this submittal. While assemblies falling into this category are not anticipated, analysis has been performed to show this configuration to be safe up to the proposed maximum nominal initial fuel enrichment of 4.75weighM.

Proposed technical specifications governing the restricted storage and filler assembly selection criteria and the requirements for storage of fuel category 2C are provided in j section Vill.1. Existing technical specification #3.9.12b.2 which allows for direct i analysis as an alternative method for determining storage pattern requirements will be  !

retained for use in any region 2 or region 1 situation.

V.5 Region Interface Restrictions Once the unrestricted loading criteria and restricted loading pattern requirements were established, a criticality assessment at the various loading pattern interfaces was performed. The methodology used and results of this assessment are summarized in sections VI.7 and VII.3 respectively. A more detailed discussion is included as Appendix A. These results were then used to determine the need for loading pattern restrictions at these interfaces. Specific interfaces analyzed for such restrictions were as follows:

i l

i Region i Unrestricted / Region 1 Restricted Region 2 Unrestricted / Region 2 Restricted om, Region 2 Unrestricted / Region 2 Restricted mm, Region 2 Restricted unum / Region 2 Restricted ~m, The region 1/ region 2 interface was not specifically analyzed due to a sufficient spacing between the regions to effectively isolate them from each other. Specific interface i restrictions determined as necessary to maintain criticality safety at these interfaces are summarized in section VII.3. Proposed technical specifications governing these restrictions are included in section VIII.l.

5-8 1

V.6 Summary This licensing document represents a request for amendments to the McGuire technical specifications related to fuel storage under several anticipated conditions / scenarios.

Figure 5-5 below illustrates in summary form the various storage configurations called for in the proposed technical specification amendments.

All current and proposed new and spent fuel storage requirements and restrictions are summarized in table 5-1 on the following page along with a specific reference to the applicable current or proposed technical specifications. Details of the requested technical specification changes are provided in section VIII.l.

Figure 5-5 Proposed Allowable Storage Configurations Fresh Fuel Equivalent McGuire McGuire Enrichment Region 1 Region 2 4.19- 4.75 (region 1) ....  ; .

1.76 - 4.75 (region 2)  :. -

Equivalent Weight % <::QM:s::

d* ?....:

n- nacurity 'ni er' assembiles must be 100% Loading Pattern 50% Checkerboard less than 2.83 equivalent weight %) ,, ,; ,,

g p 1.55 - 4.19 (region 1)

EE EE 1.55 - 1.76 (region 2)  : {f f*, e, Equivalent Weight %

am nacuilty ' niter' assemblies must be 100% Loading Pattern less than 0.86 equhalent weight %)

100% Loading Pattern

,, p ,,

i Less Than 1.55 Equivalent Weight %

100% Loading Pattern 100% Loading Pattern 5

xr g = Qualified Fuel Assembly = Qua!ified Filler Assembly 5-9

l

. Table 5-1 Current and Proposed MNS Fuel Storage Limits and Restrictions f4ew Fuel Storage Vault l uei f uel Current Current Current Proposed Proposed Proposed Category Cond6 tion Limeis/Roovirements l oad Pa* tern Reference l imits/ Recurre ment s 1oad Pattern Reference tf New ruel Max inst. Enr. 4 0% 100 % iSAR Max init. Enr. 4 75% 100 % FSAR l' 9.11.325 91.1.325 l

Spent Fuel Pool- Region 1 Area F uel fuel Current Current Current Proposed Proposed Proposed Category Condition Limits /Reauirements load Pattern Reference limits /Recuirements load Pattern Reference 1A New Fuel Max, init Enr. 4.0% 100 % FSAR Max. Init. Enr. 4.19% 100 % New T. S.

9.1.1.325 3.9.13 a .1 New Fuel FSAR 1B (Restricted) Not Apphcable Not Appkcable Not Appbcaole Max. Init. Ent, 4 75% 75% With , 9,1.1 3_2;5_

Does Not Meet Filter Assemb%s T.S.

1 A Limits 3 913a 2 Max. Init Enr 4 19%

1A trrad6ated Fuel Max. Init. Enr. 4.0% 100 % FSAR or 100 % New T. S 9.1 1.3 2 5 Quahtying Burnup* 3 9.13a.1

.A*

Irradiated fuel FSAR 18 (Restricted) Not Apphcable Not Applicable Not Apphcabie Max. init. Enr. 4.75% 75% With , 9 1.1_3_2;5, Does Not Meet Filler Assembhes New T.S.

1 A l6mits or Empty Celts 3 913a 2 IBf Region 1 Not Appbcable Not Apphcable Not Appbcabie Quahfying Burnup 25% es Fdlers New T.S.

Filler Assemblies Curve B* 3 9.13a 2 Spent Fuel Pool - Region 2 Area f uel F uel Current Current Current Proposed Proposed Proposed Category Condition Limits /Reavirements Load Pattern Reference Limits /Recuirements Load Pattern Reference 2X Irradiated Fuel Less Prohibited f rom N/A T.S # Prohibited from N/A New T. S Than 16 Days Coolec Regon 2 3 912 b Region 2 3.9.13b Oualifying Burnup Quahfying Burnup 2A Irradiated Fuel Curve 100% T S # 3 912 Curve D* 100 % Ne.v T S.

or b 1 and b 2 or 3.9 13b.1 Drrect Analys.s Deect Analys:s irradiated Fuel QuaMying Burnup FSM 28 (Restricted) Max. Init. Enr. 4.0% 50% T.S # Curve C' 50% Checkerboard ~~~91.1.324~~~

Does Not Meet Checkerboard 3 912 b 3 or With Filler Assembles New T S Category 2A limits Direct Ana'ysts or Empty Cells 3 9.13b 2 Irrad,ated Fuel 2C (Restricted) Not Applicable Not Apphcable Not Appbcable Max. Init Enr. 4 75% 50% Checkerboard New T. S.

Does Not Meet 3 9.13b.3 Category 2B lim.ts 2Bf Region 2 Not Apphcable Not Appi, cable Not Apphcable OuaMying Burnup 50% Checkerboard New T. S.

Filler Assembi.es Curve E' as filters 3 9.13b 2

' OuaMy*0 Barqup Curve Legend Curve A: Proposed Region 1 Nominal Curve - See Figure 7-1 & T. S Tatwa 3 9-1  !

Curve B: Proposed Region 1 Filter Curve . See Figure 7-1 & T S. Tabie 3 9-2 l i Curve C: Proposed L.ower Dound Region 2 Curve See Figwe 71 & T S Tabie 3 9-4 1 Curve D. Revised Region 2 Nominal Curve - See Figure 71 & T S Tabia 3 9 3 Curve E: Proposed red'on 2 I Nor Ourve - See Fegure 71 & T. S Table 3 9 5 l I

1 5-10 1

VI METIIODOLOGY OVERVIEW l l

l VI.1 General Purpose l l

This section provides an overview of the analytical methods and associated assumptions ,

used to justify the proposed amendments to the McGuire Nuclear Station technical  !

specifications and related modifications to the FSAR. Since the proposed changes relate only to variations in allowable fuel enrichments and pool storage configurations, criticality safety and thermal loading increase due to the anticipated higher discharge r burnups are the only parameters that must be reviewed and analyzed relative to 7 previously approved requirements. Review or modification of currently applicable  ;

seismic, structural, radiological, or environmental analyses is not considered necessary as l a result of these proposed changes. Previously approved or appropriately benchmarked ,

and described methodologies for performing the necessary criticality analyses are l employed as part of this submittal to demonstrate sufficient criticality safety margins. ,

VI.2 Applicable Codes, Slandards, and Regulations i t

r The following listing represents those codes, standards, and regulations which are considered to be applicable to criticality safety as it relates to new and irradiated fuel i storage. These were used as general guidelines in perfonning the necessary analyses.  !

10 CFR Part 50, General Design Criterion #62 - Prevention of Criticality ,

in Fuel Storage and Handling j NUREG - 0800, USNRC Standard Review Plan, Sections 9.1.1 & 9.1.2 l ANSI /ANS - 57.2 - 1983  ;

. NRC Reg Guide 1.13 - Dec.1975, Spent Fuel Storage Facility Design Basis  ;

t

. ANSI /ANS - 57.3 - 1983, Design Requirements for New LWR Fuel Storage

. NRC Grimes Letter Revision 1 1/18/19 l i

. ANS 51.1 - 1983, Nuclear Safety Criteda for the Design of PWR Plants  !

P

• ANSI /ANS-8.17-1984, Criticality Safety Criteria for the Handling, I Storage, and Transportation of LWR Fuel Outside Reactors (

ANSI -N16.1-1975,

• Operations with Fissionable Materials Outside Reactors" V13 Design Bases and General Assumptions f Consistent with previous license applications and amendments and in compliance with l the requirements of the above regulations and guides, the criticality analyses performed to l support the proposed FSAR and Technical Specification changes are based on the- 1 requirement that there is a 95% piobability at a 95% confidence level that the effective multiplication factor (Keff) of the fuel assembly array will be less than 0.95 (0.98 for new fuel vault under optimtun moderation conditions). The calculated Keff value must also include all appropriate biases and tolerances (mechanical, method, etc).

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As an additional safety margin to those included in the design bases above, several  ;

conservative assumptions related to the physical conditions, procedural controls, and neutron behavior are incorporated into the analyses. These ensure that the actual degree of suberiticality provided by the resulting safety limits will always be less than the analyzed value. The generally applicable of these assumptions are listed below:

• All pool storage configurations are assumed to be flooded with pure, unborated water at the temperature within the design limits of the pool which yields the largest reactivity.

Reasonable penalties for axial and width shrinkage of Boraflex are i assigned,

+ Each storage configuration analyzed is assumed to be a 2 dimensional infinite array with no axial or radial leakage,

+ Fuel assemblies are assumed to be of the Mark BW 17 x 17 design which has been shown to be the most reactive of the current and planned inventories,

• No credit is taken for burnable poisons, control rods, or other fuel assembly control components, ,

All fuel pool rack analyses have incorporated a bias which has been  !

developed to account for the B4C particle self shielding that occurs in the Boraflex neutron poison material.

The above asst;mption concerning the 2 dimensional infinite array is consistent with the current analysis for the McGuire spent fuel storage racks performed by the manufacturer.

The vendor studied the differences between a detailed 3-D model which included the effects of axial burnup, and an infinite 2-D model which did not. The conclusion reached by the vendor was that the reactivity differences were relatively small and that the infinite 2-D model bounded the results of the 3-D model with axial burnup effects for the typical i range of minimum burnup requirements. . .

Additional assumptions specifically applicable to the new fuel storage vaults are as follows:

Water density is varied to determine optimum flooding condition .

+ No supplemental neutron poisons are assumed to be present.

. All assemblies are assumed to be un-irradiated with nominal enrichment .

values of 4.75 weights U-235 including tolerances.

L 6-2 l

VL4 Computer Code / Methodology Description The SCALE system of computer codes was used to perfomi new fuel vault reactivity calculations and to model the boundary conditions that will exist at the various fuel storage region interfaces. This methodology utilizes three dimensional Monte Carlo theory and is particularly applicable to the widely-spaced fresh fuel lattices which are typical of new fuel storage vaults. Specifically, this analysis method used the CSAS25 sequence contained in Criticality Analysis Sequence No. 4 (CSAS4). CSAS4 is a ,

control module contained in the SCALE -3 system of codes. The CSAS25 sequence utilizes two cross section processing codes (NITAWL and BONAMI) and a 3-D Monte Carlo code (KENO Va) for calculating the effective multiplication factor for the system.

The 123 Group GMTH cross section library was used exclusively for this analysis.

The SCALE-3 System of Codes is certified for use and incorporated into the QA-certiDed library on Duke mainframe node PRDB. CSAS4 and the 123 Group GMTH library have been further benchmarked for criticality analysis via comparison with critical experiments to determine the applicable biases and uncertainties.

The burnup credit approach to fuel rack criticality analysis requires calculation and comparison of reactivity values over a range of burnup and initial enrichment conditions.

In order to accurately model characteristics of irradiated fuel which impact reactivity, a criticality analysis method capable of evaluating arrays of these irradiated assemblies is needed. In this license submittal, the advanced nodal method combining CASMO-3/rABLES-3/ SIMULATE-3 is used for this purpose. CASMO-3 is an integral transport theory code, SIMULATE-3 is a nodal diffusion theory code, and TABLES-3 is a linking code which reformats CASMO-3 data for use in SIMULATE-3. This methodology permits direct coupling of in-core depletion calculations and resulting fuel isotopics with out-of-core storage at:ay criticality analysis. While a CASMO-3/ SIMULATE-3 -

methodology has been approved for use in nuclear design analysis (DPC-NE-1004A, November 1992), this submital extends this methodology to criticality analysis of the spent fuel pools. Similar application of this methodology to spent fuel pool analysis has been previously approved by NRC. A detailed description of the bench marking and analysis of Duke Power's application of this burnup credit methodclogy is provided in Appendix B. This methodology - if approved - will be utilized for additional future burnup credit / criticality analysis in support of further licensing activities.

VL5 Fuel Storage Vault Methodology The new fuel vaults at the McGuire Nuclear Station are. designed exclusively for temporary storage of fresh unirradiated fuel. The ANSI /ANS - 57.3 Design Standard simply requires that Kcff be maintained at less than or equal to 0.95 under fully flooded conditions and less than or equal to 0.98 assuming optimal moderation. Analysis used to detemiine Keff in these storage racks must therefore assume maximum allowable fuel enrichments. Criticality control relies strictly on the wide spacing between individual storage locations and a specified upper limit for as-built fuel assembly enrichment. This ,

upper limit is specified in the McGuire FSAR Section 9.1.1.3.2. The absence of other factors such as soluble boron, fixed poisons, burnup effects, and fission products makes for a relatively straightforward analysis. The normally dry condition of the fuel vaults introduces the possibility of water intrusion. Consequently, full density water flooding was conservatively modeled as a normal condition in this analysis. Other less likely events which could create low density moderator conditions (i.e. foaming, misting, etc.)

dictated analysis of optimum moderator conditions as an accident condition. Vault 6-3

i

. l criticality analysis is therefore perfomied as a function of both enrichment and moderator density.

As discussed in section VI.4, the KENO Va model was used to determine the acceptability of the proposed 4.75 weight %(nominal) upper fuel enrichment limit for vault <

storage. The analysis assumed a 100%, cell loading pattern and, consequently, no loading pattern restrictions are needed or applicable in the new fuel storage vault. Results of this analysis are summarized in section VII.l.

VI.6 Burnup Credit Methodology In order to justify storage of fuel at or near the proposed upper enrichment limit established for the new fuel vaults, the concept of bmaup credit was utilized in both regions of the McGuire fuel pools. As discussed in section VI.4 above, the variable effects of fission product poisoning, fissile material production and utilization and other related effects are accurately modeled with the CASMO/ SIMULATE / TABLES methodology. Applicable biases and uncertainties are developed and become inputs to the methodology.

The basic approach is to use reactivity equivalencing techniques to construct burnup versus enrichment curves which represent equivalent and acceptable reactivity conditions over an applicable range of bumups and initial enrichments. The first curve establishes the burnup requirements for unrestricted storage or 100% cell utilization. Assemblies which fall short of the burnup requirements will require storage restrictions. A second curve is then generated to reflect the minimum requirements for restricted storage of the s

more reactive fuel assemblies which do not qualify for unrestricted storage.

i To maximize the utilization of the storage locations while accommodating these higher enriched assemblies, the analysis also focuses on determining a loading pattern which mixes the storage of projected unqualified assemblies with appropriately selected " filler" assemblies. Reactivity limits placed on these fillers are driven by the projected reactivity of the unqualified assemblies that will be stored with them such that the reactivity of the combined loading pattern meets the design criteria. Once the reactivity requirements of these fillers is determined, a third burnup curve which represents this reactivity level is constructed. This curve is then used for qualification of the filler assemblies.

Generation of the applicable burnup credit curves requires a two part calculation process.

The first part is to create two types of reactivity versus burnup curves. The first type of curve defines the maximum reactivity for the spent fuel pool such that the appropriate design criteria are met including allowances for both calculational uncertainties and i manufacturing tolerances. The second type of curve represents the reactivity versus burnup for a particular enrichment, and is generated for the range of enrichments. The intersection of the maximum design reactivity curve with the multiple enrichment curves provides data points for the second part of the process.

The second part of the process generates the burnup versus initial enrichment curves by plotting the burnup where the maximum design reactivity equals the reactivity of a particular enrichment for each enrichment. Two curves are generated which represent the qualification criteria for a particular storage configuration. Each burnup versus enrichment curve shows the minimum amount of burnup required to qualify fuel for storage in the applicable loading pattern as a function of the fuel's initial enrichment. As discussed in section V, there are two storage configurations for Region 1, normal 100%

6-4 1

1

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storage of qualified fuel and 75% storage of unqualifie.d fuel with 25% qualified filler fuel. The fresh fuel has an enrichment limit of 4.75 w/o. In Region 2 there are also two storage con 6gurations, normal 100% storage, and 50% checkerboard storage of high reactivity restricted fuel with appropriately qualiGed filler filler fuel. These curves and i supponing data are provided in section Vll.2 while additional details of the methods used I to generate these cmves are covered in Appendix B.

VI.7 Region Interface Methodology The present three region configuration in the McGuire spent fuel pools provides for physical or administratively controlled separation by a minimum of 15 cm of water between adjacent regions. The separation between region 1 and region 2 is due to a physical gap between the modules. The separation between region 2 qualified storage and the checkerboard region containing unqualified fuel is achieved by the Technical Specification (TS) requirement to maintain an empty row of cells between the two regions.

As was the case for the new fuel vault criticality analysis, the KENO Va code was used to analyze the boundary conditions that are created between the regions that share the same rack modules to assure that the storage conHgurations at these boundaries do not cause an increase in the nominal Kcff for the individual regions. Where necessary, this analysis also determined the need for new administrative restrictions at the boundaries. In performing the analyses, the base model for all region 2 checkerboard schemes are modeled as groups of four storage locations with the more reactive assemblies being modeled in the "non-cell" locations.

Other related assumptions and more detailed discussion are contained in Appendix A.

The results of the boundary condition analyses are summarized in section VII.3.

VI.8 Spent Fuel Pool Cooling Conriderations While cooling time is the more domina.;t variable for spent fuel heat load calculations, variations in discharge burnups can also have a significant impact especially in the the more limiting cases where full core off-loads with minimal cooling tirnes are being analyzed. An expected and desirable result of an increase in allowable fuel enrichments for the McGuire Nuclear Station would be a corresponding increase in the discharge burnups. Consequently, the spent fuel pool cooling system was reviewed for it's ability to maintain acceptable water temperatures under the expected thermal conditions associated with the higher discharge burnups.

Current burnups in the range of 40 to 50 GWD/MTU are the basis for the current thermal analysis which demonstrates the effectiveness of the spent fuel pool cooling system.

Batch average burnups in excess of this range are eventually anticipated with the approval of this amendment request. Based on these higher anticipated burnup levels, an analysis of the corresponding heat loads was performed assuming worst case and normal operating conditions. This analysis shows that despite these higher heat loads, spen: fuel pool water temperatures will remain within the 140 F requirements specified in NRC reg guide 1.13 and in ANSI Standard 57.2. The results of this analysis reflecting these more limiting conditions will be reDected in FSAR modifications.

6-5

VI.9 Misloaded Fuel Considerations As with the original safety assessment for the storage rack arrangements in the two McGuire spent fuel pools, this proposed enrichment upgrade creates the potential for fuel mis-loading accident conditions which were considered. In these cases, the excess negative reactivity provided by the soluble boron in the spent fuel pool water is sufficient to maintain the pool configuration at or below an acceptable Kcfr of 0.98. Accident conditions considered include the following:

1. Mis-loading of fuelin region 1:

a. Failure to provide appropriate " filler" assemblies for fuel above 4.19% actual or equivalent enrichment.

2. Mis-loading of fuelin region 2:

a. Failure to provide appropriate " filler" assemblies adjacent to fuel in category 28.

b. Failure to provide water cells adjacent to fuel in category 2C. +

Analyses performed to evaluate the above misloading accident conditions were all Sased

- on misloading unirradiated,4.75 weighs fuel assemblies into the filler or empty cell

• ~

locations required by the technical specifications. Results of those analyses are provided in section VII.4.

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VII GENERAL RESULTS OF ANALYSES This section provides the basic results of the various analyses performed in support of the proposed FSAR and Technical Specification changes. Additional discussion of the supporting analytical techniques can be found in Appendices A and B.

VII.1 New Fuel Vaults The calculated worst-case Kg, for a fuel assembly with the maximum enrichment of .

4.75 weight % (nominal) U-235 is shown below.

k,g= 0.949945 This value was specifically calculated for the Mark BW fuel design which has been shown to be the most reactive of the three fuel types which exist at McGuire. This value also includes geometrical and material uncertainties and biases at a 95 percent probability and a 95 percent confidence level as required to demonstrate criticality safety. The uncertainties considered include:

Embedded concrete tolerances Fuel Cage tolerances As specified in ANSI /ANS 57.3, the maximum k ervalue in a LWR new fuel storage vault shall be less than or equalto 0.98 under optimum moderator conditions and less than or equal to 0.95 under fully flooded conditions. The analytical result shown above indicates that this criteria has been met.

7-1

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VII.2 Fuel Assembly Burnup Requirements The results of the criticality analysis used to determine burnup requirements for the various fuel loading configurations in both regions of the McGuire pools are summarized by the five burnup curves shown in figure 7-1 below. Specific data points generated by the criticality analysis and used to create these 5 burnup curves are shown in Table 7-1 on the following page.

Figure 7-1 McGuire Fuel Pool Storace Curves i Reg.on 2 Filer Curve E 6 0 --

O Region 2100% Curve D 5 Regon 2 CB Curve C

~~

O Region 1 FWier- Curve B m f Region 1100% Cu've A

s y40--

b 3

o

• 30--

c.

?

e g20- -

m d 10J l +

0 .' / s

, '.+'4--+- '

2.00 2.50 3.00 3.50 4.00 4.50 5.00 Initial Enrichment (%U-235)

Minimum requirements for unrestricted (100%) fuel storage in region 1 ( Category 1 A).

Curve A Region I assemblies not meeting curst A requirements must be stored in a 75% load pattern in region I with qualified filler issemblies (Fuel Category 111).

Curve Il Minimum requ!rerlents for reg *on 1 filler assembhes (Category 111r).

Minimum requirements for 50% loading pattern in region 2 with qualified assys (Category 211).

Curve C Region 2 assemblies not meeting Curse C requirements must be stored in a 50% loading pattern with blocked empty cells (Category 2C).

Curve D Minimum requirements for unrestricted storage in region 2 (Category 2A).

Curve E Minimum requirements for region 2 filler assemblies (Category 211r).

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Table 7-1 ,

McGuire Fuel Pool Storace Oualification Reauirements Region Enrich 3.00 3.50 4.00 4.50 4.75 1 -ment 100 % Ilurnup - -

-1.29 1.92 3.40 icwo wro, liller llurnup 1.57 13.30 18.32 23.36 25.84 icwn wro, Region Enrich 2.00 2.50 3.00 3.50 4.00 4.50 5.00 2 -men t 100% Iturnup 10.54 17.96 24.64 30.86 36.75 42.38 47.81 (cwp/una Checker  !!urnup 4.22 10.75 16.80 22.41 27.92 33.14 38.16 -

board '""'**

Filler Burnup 18.03 26.71 33.79 40.56 46.83 52.86 58.69 icwn um mer b

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f VII.3 Region Interface Restrictions i

Region 1 l As discussed earlier in section V and summarized in table 5-1, the region 1 area of the fuel pools will be made up of two sub regions (I A and IB) to accommodate fuel above and below the 4.19 weighi% equivalent enrichment value. The boundary conditions between these regions were analyzed in an attempt to determine the worst geometry configuration for neutronic coupling between the cells of differing enrichments. In this process it was discovered that to assure that the boundary between regions will have no effect on the keff , the border between regions must be a row of alternating " filler" assemblies and the " unqualified" assemblies. A full row of unqualified assemblies serving as this boundary would not be acceptable.

The distance from region 1 to region 2 is sufficient to isolate the two regions.

Consequently no loading restrictions are necessary at the interface between the two regions.

Region 2 The Region 2 area of the pools were re analyzed to accommodate 3 separate sub regions as summarized in table 5-1. Fuel which can be stored without restriction makes up region 2A. Fuel which must be checkerboarded 50% with " filler" assemblies defines region 2B and fuel which must be checkerboarded 50% with water cells will make up a region 2C.

The interface restrictions between region 2B and 2C and between 2A and 2C are basically the same. As opposed to the boundary between region 2A and 2B where any region could bound the other on all four sides, the calculations reveal that for the boundaries between 2B and 2C, along with region 2A and 2C, only two opposite sides of one region can bound the other. The other two sides must either bound the fuel pool wall or an empty row of cells.

The distance from region 2 to region 1 is sufficient to isolate the two regions.

Consequently no loading restrictions are necessary at the interface between the two regions.

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All proposed boundary restrictions as discussed above are summarized below:

6esion Interface Restrictions Region 1 A and 1B Row cf region 1B bounding region 1 A must be a row of afternating region 18 fueltypes l and region 1B fillerlocations.

l Region 2A and 28 No Interface Restrictions At least 2 opposite sides of region 2C shall be Region 2A or 2B bounded by either a row of empty water cells or and 2C the fuel pool wall. The remaining side (s) may be either region 2A or region 28 or both.

Region 1 and 2 No interf ace Restrictions L

VII.4 Fuel Misloading Accident Analysis The following table summarizes the results of specific analyses perfomied to verify that sufficient margin is provided by the soluble boron to maintain the pool configuration at or below Keff of 0.98 following various postulated fuel mistoading accidents.

Summary of Mistoadine Accident Analysis Mi loading Accident Kerr Maintained at or Ennt Description IIelow 0.98 with 2000 ppm .

Soluble Iloron t Regioni 1 " Filler" Location Mistoaded with Yes 4.75 weight % Fuel t

Region 2 " Filler" Location Misloaded with Yes 4.75 weigh % Fuel RegionT Empty Cell Location Misloaded with Yes 4.75 weight % Fuel 7-5

• N VIII PROPOSED TECIINICAL SPECIFICATION / FSAR MODIFICATIONS This section contains the proposed modifications to the MNS Technical Specifications being requested with this submittal as well as a discussion of the resulting necessary

. changes that will be made in the McGuire Nuclear Station FSAR upon approval of this amendment request or in the very first annual update which follows NRC's approval.

VIII.1 Technical Specification Changes The following changes are those necessary to raise the maximum fuel enrichment allowed for use at the McGuire Station to 4.75 weight %. Specific spent fuel pool loading restrictions necessary to maintain acceptable criticality safety margins for all new and irradiated fuel with initial enrichments at or below this new value are ensured by these changes.

Administrative controls necessary to ensure compliance with these revised technical specifications are discussed in section IX.

The new fuel storage vaults were specifically analyzed and determined to provide acceptable criticality safety margins for fuel enrichments at or below the new 4.75 weight % limit. Consequently no loading pattern storage restrictions or related technical specifications are necessary for the new fuel storage vaults.

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b Current Reunirements:

9 Technical Specification

Reference:

3/4.9 Refueline Onerations UNIT 1 ONLY Section 3/4.9 Refueling Operations r

LIMITING CONDITION FOR OPERATION i

3.9.12 Fuel is to be stored in the spent fuel storage pool with

a. The boron concentration in the spent fuel pool maintained at greater than or equal to 2000 ppm; and

b. Storage in Region 2 restricted to irradiated E ' mhich has decayed at least 16 days and one of the following:

1) Fuel which has been qualified in accordance with Table 3.9-1; or

2) Fuel which has been qualified by means of an analysis using NRC approved methodology to assure with a 95 percent probability at a 95 percent confidenca level that k,gti s no greater than 0.95 including all ,

uncertainties; or i

3) Unqualified fuel stored in a checkerboard configuration. In the event ,

checkerboard storage is used, one row between normal storage l locations and checkerboard storage locations will be vacant. I APPLICABILITY:

During storage of fuelin the spent fuel pool.

1 ACTION:

a. Suspend all actions involving the movement of fuel in the spent fuel pool if it is determined a fuel assembly has been placed in the incorrect Region until such time as the correct storage location is determined. Move the assembly to its correct location before resumption of any other fuel movement.

b. Suspena all actions involving the movement of fuelin the spent fuel poolif it is determined the pool boron concentration is less than 2000 ppm, until such time as the boron concentration is increased to 2000 ppm or greater.

c. The provisions of Specification 3.0.3 are not applicable.  !

i 8-2

Current Reauirements: (Con't)

UNIT 1 ONLY SURVElLLANCE REQUIREMENTS:

4.9.12.a Verify all fuel assemblies to be placed in Region 2 of the spent fuel pool are within the enrichment and burnup limits of Table 3.9-1 or that kg s 0.95 by checking the assemblies' design and burnup documentation or the assemblies' qualifying analysis documentation respectively.

b. Verify at least once per 31 days that the spent fuel pool boron concentration is greater than 2000 ppm.

f I

l 8-3

Current Reauirernents: (Con't)

I UNIT 2 ONLY l l

Section 3/4.9 Refueling Operations LIMITING CONDITION FOR OPERATION 3.9.12 Fuel is to be stored in the spent fuel storage pool with

a. The boron concentration in the spent fuel pool maintained at greater than or equal to 2175 ppm; and

b. Storage in Region 2 restricted to irradiated fuel which has decayed at least 16 days and one of the following:

1) Fuel which has been qualified in accordance with Table 3.9-1; or

2) Fuel which has been qualified by means of an analysis using NRC approved methodology to assure with a 95 percent probability at a 95 percent confidence level that kg is no greater than 0.95 including all uncertainties; or

3) Unqualified fuel stored in a checkerboard configuration. In the event checkerboard storage is used, one row between normal storage locations and checkerboard storage locations will be vacant.

APPLICABILITY:

During storage of fuel in the spent fuel pool.

ACTION:

a. Suspend all actions involving the movement of fuel in the spent fuel pool if it is determined a fuel assembly has been placed in the incorrect Region until such time as the correct storage location is determined. Move the assembly to its correct location before resumption of any other fuel movement.

b. Suspend all actions involving the movement of fuelin the spent fuel pool if it is determined the pool boron concentration is less than 2175 ppm, until such time as the boron concentration is increased to 2175 ppm or greater,

c. The provisions of Specification 3.0.3 are not applicable.

8-4

Current Reouirements: (Con't)

UNIT 2 ONLY SURVEILLANCE REQUIREMENTS:

l i

4.9.12.a Verify all fuel assemblies to be placed in Region 2 of the spent fuel pool are within the enrichment and burnup limits of Table 3.9-1 or that kett s 0.95 by checking the assemblies' design and burnup documentation or the assemblies' qualifying analysis documentation respectively.

b. Verify at least once per 31 days that the spent fuel pool boron concentration  ;

is greater than 2175 ppm.  !

i 8-5

l 1

Current Reauiremente (Con'O Table 3.9-1 i Minimum Oualifyino Burnuo Versus initial Enrichment for Reoion 2 Storaos 1

I initial Enrichment Assembly Burnup w/o U-235 (GWD/MT) 1.4................................................................................ 0.00 1.5............................................................................................... 2.50

• 1.6............................................................................................... 5.00 1.7 . . ... ... ........... ...... .............. ... .......... .................................. 6.65 <

1 .8 ... ................ ....... .... ........................... .............. . . ..................... 8.30 ,

1.9.................................................................................................... 9.95 t 2.0...............................................................................................11.60 ,

2.1 . . . . . . . . . . . . ....... .......... ..... ..... ............ .... ... ... ......................... 1 3 .2 0 1 2.2.........................................................................................14.60 2.3 . . ........................................................................................16.00 1 2.4............................................................................................17.40 (.

2.5.................................................................................................18.80 '

2.6................... ..................................................................20.20 2.7...........................................................................................21.40 t 2.8....................................................................................................22.60 ,

2.9..................................................................................................23.90 .

I 3.0................................................................................................25.20 .

3.1...................................................................................................26.60 i 3.2...............................................................................................27.80 3.3...................................................................................................28.93 '

3.4.................................................................................................30.07 3.5..................................................................................................31.20  !

i 3.6..................................................................................................... 2.26  :

l 3.7............ ...................................................................................33.32 i

+

3.8....................................................................................................34.38 l 3.9...................................................................................................35.44  !

4.0...................................................................................................36.50 >

a t

e I

6 i

l i l

! i i

t t

8-6

Proposed Reauirements: i l

l Technical Specification

Reference:

3/4.9 Refuelino Onerations  !

l UNITS 1 and 2 l

REFUELING OPERATIONS 3/4.9.12 SPENT FUEL POOL BORON CONCENTRATION LIMITING CONDITION FOR OPERATION 3.9.12 The boron concentration in the spent fuel pool shall be within the limit specified in the COLR.

APPLICABILITY:

During storage of fuelin the spent fuel pool.

ACTION:

a. Immediately suspend movement of fuel assemblies in the spent fuel pool and initiate action to restore the spent fuel pool boron concentration to within its limit.

b. The provisions of Specification 3.0.3 are not applicable.

SURVEILLANCE REQUIREMENTS:

4.9.12 Verify at least once per 31 days that the spent fuel pool boron concentration is within its limit.

i 8-7

f Proposed Reauirements: (Con't) 3/4.9.13 SPENT FUEL ASSEMBLY STORAGE LIMITING CONDITION FOR OPERATION 3.9.13 Storage of new or irradiated fuelis limited to the configurations described in this specification.

a. New or irradiated fuel may be stored in Region 1 of the Spent Fuel Pool in accordance with these limits:

1) Unrestricted storage of fuel meeting the criteria of Table 3.9-1; or

2) Restricted storage in accordance with Figure 3.9-1, of fuel which does Hol meet the criteria of Table 3.9-1; or

3) Another configuration determined to be acceptable by means of an analysis to ensure that k ett i s less than or equal to 0.95.

b. New or irradiated fuel which has decayed at least 16 days may be stored in Region 2 of the Spent Fuel Poolin accordance with these limits:

1) Unrestricted storage of fuel meeting the criteria of Table 3.9-3; or

2) Restricted storage in accordance with Figure 3.9-2, of fuel which meets the criteria of Table 3.9-4; or

3) Checkerboard storage in accordance with Figure 3.9 3 of fuel which does nol meet the criteria of Table 3.9-4; or

4) Another configuration determined to be acceptable by means of an analysis to ensure that k ett i s less than or equal to 0.95.

APPLICABILITY:

During storage of fuelin the spent fuel pool.

ACTION:

a. Immediately initiate action to move the noncomplying fuel assembly to the correct location.

b The provisions of Specification 3.0.3 are not applicable.

8-8

Proposed Reauirements: (Con't)

SURVEILLANCE REQUIREMENTS:

4.9.13 Prior to storing a fuel assembly in the spent fuel storage pool, verify by administrative means the initial enrichment and burnup of the fuel assembly are in accordance with Specification 3.9.13.

l l

l 8-9

i Pronosed Reauirements: (Con't)

Table 3.9-1 Minimum Qualifving Burnuo Versus Initial Enrichment for Unrestricted Region 1 Storage Initial Enrichment Assembly Burnup Weight % U-235 (GWD/MTU) 4.19 (or less) 0 4.20 0.04 4.50 1.92 4.75 3.40 5

$ 4 _

R t o

3-T ACCEPTABLE E3 2-k8 1- UNACCEPTABLE 4

0 -  :  : -

4.00 4.25 4.50 4.75 Initial Enrichment (Weight % U-235) l l

l 8 -10 1

- - -- .. - ~. . . . - .

v Pronosed Reuniremenk: (Con't)

Table 3.9-2 l

Minimum Qualifying Burnuo Versus initial Enrichment for Region 1 Filler Assemblies l t

t Initial Enrichment Assembly Burnup Weiaht% U-235 (GWD/MTU) i 2.92 (or less) 0 3.00 1.57 3.50 13.30 4.00 18.32  !

4.50 23.36 4.75 25.84

?

30 S 25 -

$ 20 -

?=

ACCEPTABLE f S

h 15 --

fe10 UNACCEPTABLE i

o

& 5--

0 -: . .

2.50 3.00 3.50 4.00 4.50 4.75 Initial Enrichment (Weight % U-235) l f

8-11 l l

i

l Proonsed Reauirements- (Con't)

Table 3.9-3 .

Minimum Qualifyino Burnuo Versus initial Enrichment for Unrestricted Recion 2 Storage initial Enrichment Assembly Burnup l Weight % U-235 (GWD/MTU) 2.00 (or less) 10.54 ,

2.50 17.96 3.00 24.64 3.50 30.86 4.00 36.75 4.50 42.38 4.75 45.10 60 --

F 50 ACCEPTABLE R

S 40 -

52, n.

y 30 --

s 2 20 - l l

5 UNACCEPTABLE j 10 ' l 0  : .  :  :

2.00 2.50 3.00 3.50 4.00 4.50 4.75 initial Enrichment (Weight % U-235) 8 - 12

Pronosed Reauirements: (Con't)

Table 3.9-4 Minimum Qualifying Burnuo Versus Initial Enrichment for Restricted Reaion 2 Storage with Fillers initial Enrichment Assembly Burnup Weight % U-235 (GWD/MTU) 2.00 (or less) 4.22 2.50 10.75 3.00 16.80 3.50 22.41 4.00 27.92 4.50 33.14 4.75 35.65 60 -

$ 50 -

40 . ACCEPTABLE E

a.

E 30 -

E ca 2 20 --

E

$ 10 -- UNACCEPTABLE O.

2.00 2.50 3.00 3.50 4.00 4.50 4.75 initial Enrichment (Weight % U-235) 8 - 13

l l

Pronosed Reauirements: (Con't)

- Table 3.9-5 Minimum Qualifyino Burnuo Versus initial Enrichment for Region 2 Filler Assemblies initial Enrichment Assembly Burnup  !

Weight % U-235 (GWD/MTU)  !

2.00 (or less) 18.03  ;

2.50 26.71 3.00 33.79 3.50 40.56 4.00 46.83  !

4.50 52.86 t 4.75 55.78 60 --

ACCEPTABLE F 50 .

R S 40 --

e

a. ,

y 30 --

p 20 f UNACCEPTABLE E '

j 10 -

0

l l  ;

2.00 2.50 3.00 3.50 4.00 4.50, 4.75 ,

I initial Enrichment (Weight % U-235)  !

l 8 - 14 l

)

Pronosed Reauirements: (Con't)

Figure 3.9-1 Reauired 3 out of 4 Loadino Pattern for Restricted Reaion 1 Storage RESTRICTED RESTRICTED RESTRICTED RESTRICTED FUEL FUEL FUEL FUEL RESTRICTED F1LLER RESTRICTED FILLER FUEL LOCATION FUEL LOCATION l

l RESTRICTED RESTRICTED RESTRICTED RESTRICTED FUEL FUEL FUEL FUEL

^

- +,

l .

RESTRICTED FILLER RESTRICTED FILLER FUEL LOCATION FUEL LOCATION

~ ,,

Restricted Fuel: Fuel which does nni meet the minimum burnup requirements of Table 3.9-1. (Fuel which does meet the requirements of Table 3.9-1 may be placed in restricted fuel locations as needed)

Filler Location: Either fuel which meets the minimum burnup requirements of Table 3.9-2, or an empty Cell.

Boundary Condition: Any row bounded by a Region 1 Unrestricted Storage Area shall contain a combination of restricted fuel assemblies and filler locations arranged such that no restricted fuel assemblies are adjacent to each other.

Example: In the figure above, row 1 or column 1 can DQ1 be adjacent to a Region 1 Unrestricted Storage Area, but row 4 or column 4 can be.

8 -15

Proposed Reauirements: (Con't)

Ficure 3.9-2 Reauired 2 out of 4 Loading Pattern for Restricted Region 2 Storage l

i l

RES TRICTED FILLER RESTRICTED FILLER FUEL LOCATION FUEL LOCATION

?$ h FILLER RESTRICTED FILLER RESTRICTED LOCATION FUEL LOCATION FUEL j 4

, RESTRICTED FILLER RESTRICTED FILLER

FUEL LOCATION FUEL LOCATION I

l v l i

FILLER RESTRICTED FILLER RESTRICTED LOCATION FUEL LOCATION FUEL ga  ;;dp Restricted Fuel: Fuel which meets the minimum bumup requirements of Table 3.9-4.

Filler Location: Either fuel which meets the minimum burnup requirements of Table 3.9-5, or an empty cell.

Boundary Conddion: No restrictions on boundary assemblies.

i I

8 -16 1

_ l

_ _ - - =_ .-

Pronosed Reauirements: (Con't)

Fiaure 3.9-3 Reauired 2 out of 4 Loadina Pattern ~

l for Checkerboard Rea_ ion 2 Storaa_ e  ;

~

$4i sm OHECKERBOARE' EMPTY OHECKERBOARE EMPTY FUEL CELL FUEL CELL

, #n> (gp;.

f N fhv /

EMPTY CHECKERBOARE EMPTY CHECKERBOARE CELL FUEL CELL FUEL l s

f, M <- ' + gggg, gj

+

' f@l '

OHECKERBOARE' EMPTY OHECKERBOARE EMPTY FUEL CELL FUEL CELL

^ #

'f*T!i?2^^%E 8

- **1 ge gjerK!M EMPTY OHECKERBOARE EMPTY OHECKERBOARE j CELL FUEL CELL FUEL ,

sr + - ggf +

)

Checkerboard Fuel: Fuel which does ani meet the minimum burnup requirements of Table 3.9-4. (Fuel which does meet the requirements of Table 3.9-4 may be placed in checkerboard fuellocations as needed) )

Boundary Condition: At least two opposite sides shall be bounded by either an empty row of cells, or a spent fuel pool wall.

8-17

l Current Reauirements: ,

i Technical Specification

Reference:

3/4.9 Refuelino Onerations j UNIT 1 ONLY BASES 3/4.9.12 FUEL STORAGE - SPENT FUEL STORAGE POOL The requirements for fuel storage in the spent fuel pool on 3.9.12 (a) and (b) ensure that: (1) the spent fuel pool will remain subcritical during fuel storage; and (2) a uniform boron concentration is maintained in the water volume in the spent fuel pool for l I

reactivity control. The value of 0.95 or less for Keff which includes all uncertainties at the 95/95 probability / confidence level as described in Section 9.1.2.3.1 of the FSAR is the acceptance criteria for fuel storage in the spent fuel pool. Table 3.9-1 is conservatively developed in accordance with the acceptance criteria and methodology referenced in Section 5.6 of the Technical Specifications. Storage in a checkerboard configuration in Region 2 meets all the acceptance criteria referenced in Section 5.6 of the Technical Specifications and is verified in a semi-annual basis after initial verification through administrative controls.

The Action Statement applicable to fuel storage in the spent fuel pool ensures that: (1) the spent fuel pool is protected from distortion in the fuel storage pattern that could result in a critical array during the movement of fuel; and (2) the boron concentration is maintained at 2000 ppm during all actions involving movement of fuel in the spent fuel {'

pool.

The Surveillance Requirements applicable to fuel storage in the spent fuel pool ensure that: (1) fuel stored in Region 2 meets the enrichment and burnup limits of Table 3.9-1 or the Keff s 0.95 acceptance criteria of an analysis using NRC approved methodology; and (2) the boron concentration meets the 2000 ppm limit.

8 - 18

Current Reauirements: (Con't)

Technical Specification

Reference:

3/4.9 Refuelino Onerations UNIT 2 ONLY BASES 3/4.9.12 FUEL STORAGE - SPENT FUEL STORAGE POOL The requirements for fuel storage in the spent fuel pool on 3.9.12 (a) and (b) ensure that: (1) the spent fuel pool will remain subcritical during fuel storage; and (2) a uniform boron ccncentration is maintained in the water volume in the spent fuel pool for reactivity control. The value of 0.95 or less for Keff which includes all uncertainties at the 95/95 probability / confidence level as described in Section 9.1.2.3.1 of the FSAR is the acceptance criteria for fuel storage in the spent fuel pool. Table 3.9-1 is conservatively developed in accordance with the acceptance criteria and methodology referenced in Section 5.6 of the Technical Specifications. Storage in a checkerboard configuration in Region 2 meets all the acceptance criteria referenced in Section 5.6 of the Technical Specifications and is verified in a semi-annual basis after initial verification through administrative controls.

The Action Statemerd applicable to fuel storage in the spent fuel pool ensures that: (1) the spent fuel pool is protected from distortion in the fuel storage pattern that could result in a critical array during the movement of fuel; and (2) the boron concentration is  !

maintained at 2175 ppm during all actions involving movement of fuel in the spent fuel pool.

The Surveillance Requirements applicable to fuel storage in the spent fuel pool ensure that: (1) fuel stored in Region 2 meets the enrichment and burnup limits of Tab:e 3.9-1 ,

or the Keff s 0.95 acceptance criteria of an analysis using NRC approved methcdology; and (2) the boron concentration meets the 2175 ppm limit. ,

L i

1 8 -19

Proposed Reauirements:

Technical Specification

Reference:

3/4.9 Refueline Operations UNITS 1 and 2 BASES 3/4.9.12 and 3/4.9.13 SPENT FUEL POOL BORON CONCENTRATION and SPENT FUEL ASSEMBLY STORAGE The requirements for spent fuel pool boron concentration specified in Specification 3.9.12 ensure that a minimum boron concentration is maintained in the pool. The requirements for spent fuel assembly storage specified in Specification 3.9.13 ensure that the pool remains suberitical. The water in the spent fuel storage pool normally contains soluble boron, which results in large suberit.W.lity margins under actual operating conditions. However, the NRC guidelines based upon the accident condition in which all soluble poison is assumed to have been lost, specify that the limiting ket , of 0.95 be evaluated in the absence of soluble boron. Hence the design of the spent fuel storage racks is based on the use of unborated water, which maintains each region in a +

subcritical condition during normal operation with the spent fuel pool fully loaded. The double contingency principle discussed in ANSI N-16.1-1975 and the April 1978 NRC letter (Ref. 4) allows credit for soluble boron under other abnormal or accident ,

conditions, since only a single accident need be considered at one time. For example, the most severe accident scenario is associated with the movement of fuel from Region 1 to Region 2, and accidental misloading of a fuel assembly in Region 1 or Region 2. -

This could increase the reactivity of the spent fuel pool. To mitigate these postulated criticality relateo accidents, boron is dissolved in the pool water.  ;

Specification 3.9.13.a.3 and 3.9.13.b.4 allow for specific criticality analysis for configurations other than those explicitly defined in Specification 3.9.13. These analyses would require using NRC approved methodology to ensure that kett s 0.95 with a 95 percent probability at a 95 percent confidence level as described in Section 9.1 of the FSAR. ,

In verifying the design criteria of kets s 0.95, the criticality analysis assumed the most conservative conditions, i.e. fuel of the maximum permissible reactivity for a given configuration. Since the data presented in Specification 3.9.13.a and 3.9.13.b represents the maximum reactivity requirements for acceptable storage, substitutions of less reactive components would also meet the kett s 0.95 criteria. Hence, any non-fuel component may be placed in a designated empty cell location. Likewise, an empty cell,  ;

or a non-fuel component may be substituted for any designated fuel assembly location.  :

~

These, or other substitutions which will decrease the reactivity of a particular storage cell will only decrease the ;verall reactivity of the spent fuel storage pool. i If both restricted and unrestricted storage is used in Region 1, an additional criteria has  ;

been imposed to ensure that the boundary row between these two configurations would  ;

not locally increase the reactivity above the required limit. Likewise if checkerboard I 8-20

_._______..I

. I Proposed Reanirements: (Con't) storage is used in Region 2, an additional restriction has been imposed on the boundaries of the checkerboard storage region to ensure that the reactivity would not increase above the required limit. No other restrictions on region interfaces are necessary.

For storage in Region 2 requiring loading pattern restrictions, (per Specifications 3.9.13.b.2 or 3.9.13.b.3) fuel may be stored in either the " cell" or "non-cell" locations.

" Cell" locations are the areas inside the fabricated storage cells and "non-cell" locations are the storage locations created by arranging the fabricated storage cells in a checkerboard configuration. Hence the "non-cell" locations are the areas defined by the outside walls of the 4 adjacent " cell" locations.

The action statement applicable to fuel storage in the spent fuel pool requires that action must be taken to preclude the occurrence of an accident or to mitigate the consequences of an accident in progress. This is most efficiently achieved by immediately suspending the movement of fuel assemblies. Prior to the resumption of fuel movement, the requirements of the LCOs must be met. This requires restoring the soluble boron concentration and the correct fuel storage configuration to within the corresponding limits. This does not preclude movement of a fuel assembly to a safe position.

The surveillance requirements ensure that the requirements of the two LCOs are satisfied, namely boron concentration and fuel placement. The boron concentration in the spent fuel pool is verified to be greater than or equal to the minimum limit. The fuel assemblies are verified to meet the suberiticality requirement by meeting either the initial enrichment and burnup requirements of Table 3.9-1 through 3.9-5, or by using NRC approved methodology to ensure that ket s 0.95. By meeting either of these requirements, the analyzed accidents are fully addressed. )

The fuel storage requirements and restrictions discussed here and applied in section 3.9.13 are based on a maximum allowable fuel enrichment of 4.75 weight % U-235.

The enrichments listed in Tables 3.9-1 through 3.9-5 are nominal enrichments and include uncertainties to account for the tolerance on the as built enrichment. Hence the ,

as built enrichments may exceed the enrichments listed in the tables by up to 0.05 l weight % U-235. Qualifying bumups for enrichments not listed in the tables may be i linearly interpolated between the enrichments provided. This is because the reactivity of an assembly varies linearly for small ranges of enrichment. ,

l REFERENCES 1

1. " Regulatory Guide 1.13: Spent Fuel Storage Facility Design Basis", U.S. Nuclear j Regulatory Commission, Office of Standards Development, Revision 1, December 1976.

2 " Design Objectives for Light Water Reactor Spent Fuel Storage Facilities at Nuclear Power Stations", American Nuclear Society, ANSI N210-1976/ANS-57.2, April 1976.

i l

8 -21 i

Pronosed Reauirements: (Con't)

3. FSAR, Section 9.1.

4. Double contingency principle of ANSI N16.1-1975, as specified in the April 14,1978 NRC letter (Section 1.2) and implied in the proposed revision to Regulatory Guide 1.13 (Section 1.4, Appendix A).

l 1

8 -22 l

Current Reunirements l Technical Specification

Reference:

5.6 Fuel Storace  !

l Section 5.0 DESIGN FEATURES 5.6 Fuel Storace CRITICALITY 5.6.1 The new and spent fuel storage racks are designed and shall be maintained with:

a. A k ne quivalent e to less than or equal to 0.95 when flooded with unborated water, which includes a conservative allowance for uncertainties as described in Section 9.1.2.3.1 of the FSAR, and

b. A nominal 21-inch center-to-center distance between fuel assemblies placed in the new fuel storage vault racks, and

c. A nominal 10.4-inch and a 9.125 inch center-to-center distance between fuel assemblies placed in Region 1 and Region 2 storage racks, respectively, in the spent fuel storage pool.

DRAINAGE 5.6.2 The spent fuel storage pool is designed and shall be maintained to prevent inadvertent draining of the pool below elevation 745 ft. 7 in.

CAPACITY 5.6.3 The spent fuel storage pool is designed and shall be maintained with a storage capacity limited to no more than 1463 fuel assemblies (286 spaces in Region 1 and 1177 spaces in Region 2) having an initial enrichment less than or equal to 4.0 weight percent U-235.

8 - 23

Proposed Reunirements:

Technical Specification

Reference:

5.6 Fuel Storace Section 5.0 DESIGN FEATURES 5.6 Fuel Storage CRITICALITY 5.6.1 a. The spent fuel storage racks are designed and shall be maintained with k ort s 0.95 if fully flooded with unborated water as described in Section 9.1 of the FSAR; and

b. The new fuel storage racks are designed and shall be maintained with k,,, s 0.95 if fully flooded with unborated water; and k gg e s 0.98 if moderated by aqueous foam as described in Section 9.1 of the FSAR.

DRAINAGE 5.6.2 The spent fuel storage pool is designed and shall be maintained to prevent inadvertent draining of the pool below elevation 745 ft. 7 in.

CAPACITY 5.6.3 The spent fuel storage poolis designed and shall be maintained with a storage capacity limited to no more than 1463 fuel assemblies (286 spaces in Region 1 and 1177 spaces in Region 2).

8-24

VIII.2 Proposed FSAR Modifications Sections 4.3, Nuclear Design, and 9.1, Fuel Storage and Handling, are the only sections of the McGuire FSAR which will require modification as a result of the proposed technical specification changes detailed in this license amendment submittal. )

Specific language will be developed upon approval of this amendment request. In general however, changes will focus on the following sub-sections:

43.2.6 Criticality of the Reactor During Refueling and Criticality of Fuel Assemblies The discussion of the codes and methodology used in the criticality analysis would be updated to reflect the use of both the CASMO-3/ SIMULATE-3 and SCALE / KENO Va methodologies.

9.1.1.3.2 Criticality Evaluation Assumption number 5 in the listing of those made in evaluating criticality safety will be changed to reflect the increase in the upper enrichment limit to 4.75 weight % with a tolerance of .05 weight %.

9.1.2.23 Applicable Codes and Standards The discussion on page 9-10 which references specific burnup requirements for unrestricted fuel storage in region 2, and describes storage restrictions for fuel not meeting these requirements will be changed. The revision will reference specific burnup requirements for restricted and unrestricted storage requirements for fuel being placed in either region 1 or region 2.

9.1.233 Normal Storage The statement which follows the assembly parameters tabulation stating that no U-235 burnup is assumed for region 1 storage will no longer be accurate. The proposed license amendment does utilize bumup credit for region 1 storage of fuel with initial enrichments exceeding 4.19 weight %.

9.1.2.3.5 Criticality Calculations This section of the McGuire FSAR discusses the calculational methodology employed to ensure criticality safety for fuel storage. This section will be modified to reference the new methodology used to support the proposed license changes and being requested for approval as part of this submittal.

9.1.3.2 Spent Fuel Cooling System While the spent fuel cooling system will not be modified as a result of this submittal, the normal and abnormal heat load assumptions will change as a result of the higher

• anticipated discharge burnups. The results of an analysis based on these heat loads will be reflected in this section.

8-25

e IX ADMINISTRATIVE CONTROLS Fuel storage restrictions currently applicable to the two spent fuel pools at MNS include both the qualification requirements as stated in the technical specifications and the administrative controls to ensure proper selection and placement of new and irradiated fuel in the two storage regions. These controls include individual assembly record keeping and review to accurately track and verify reacdvity-related fuel characteristics, specific fuel handling procedures and restrictions, and the use of cell blocking devices to preclude fuel p;acement in cells which must remain empty in a checkerboard loading arrangement. For the most part, the procedural portions of the existing restrictions will be retained under the proposed technical specification revision with only the qualification requirements being modified to accommodate the higher fuel enrichments and the new fuel loading patterns being introduced.

IX.I Current Loading Restrictions The current Technical Specifications identify characteristics and associated loading restrictions for 3 separate fuel categories as follows:

Fuel Category Applicable Region Loading Pattern Restriction 1A Region 1 None 2A Region 2 None 2B Region 2 50% Fuel / 50% Empty Cells IX.2 Proposed Loading Restrictions The proposed technical specification revision will replace the above fuel categories with 5 modified fuel categories which are listed below with their respective loading restnctions:

Fuel Category Applicable Region Loading Pattern Restriction 1A Region 1 None 1B Region 1 75% Fuel / 25% Fillers 2A Region 2 None 2B Region 2 50% Fuel / 50% Fillers 2C Region 2 50% Fuel / 50% Empty Cells Each of fuel categories IA,2A, and 2B, will have a cr;rresponding burnup curve as discussed in section VIII which represents the maximum reactivity level allowed by that category. Categories IB and 2C are simply limited to new or irradiated fuel with initial enrichments at or below 4.75 weight % (nominal).

9-1 J

j

L Categories iB and 2C which respectively require the most restrictive loading pattern in each region are intended to accommodate any new or discharged assemblies which do not qualify for the less restrictive loading patterns of categories l A,2A, and 28. The primary use for these categories will be temporary storage of new (fresh) fuel assemblies above 4.19 weight % initial enrichment.

IX.3 Filler Assembly Requirements As noted above, the designated loading patterns for categories IB and 2B require the placement of " filler" assemblies into appropriate locations of the loading pattern.

Consequently,2 additional fuel subcategories are identified for the purpose of defining qualification requirements for these fillers. The filler categories are summarized as follows:

Fuel Category Application 1 Bf Region 1 Filler Fuel 2 81 Region 2 Filler Fuel As is the case for fuel categories l A,2A, and 2B, qualification of fuel for placement into these " filler" fuel categories is governed by separate burnup curves which are detailed in ,

section VIII.

IX.4 Pre-Staging of Checkerboard Areas The added flexibility provided by this proposed license amendment, while allowing for increased storage efficiency, does add some degree of complexity through the allowance of 2 loading configurstions in region 1, and 3 loading configurations in region 2. It should be noted, however that the majority of the spent fuel discharges from the McGuire reactors will qualify for unrestricted storage in either region 1 or region 2, thus keeping the quantity of fuel subject to a misplacement accident to a minimum.

Procedural controls to ensure correct placement of new and irradiated fuel will be carefully developed and implemented through ongoing interactions between the fuel management organization and the McGuire station reactor engineering group.

Additionally, specific pre-staging of the filler assemblies and empty cell blocking devices required for the three restricted storage configurations will occur as needed to further protect against fuel misplacement. Specific pre-staging plans for the three possible restricted configurations are as follows:

Category IB fuel assemblies which are required to be placed into a 75% (3 of

4) loading pattern will only be moved into the region 1 area of the fuel pools after the appropriate number of " filler" assemblies needed for this pattern have been qualified and put in place. This clearly identifies the region 1 rack locations that can safely be used for storing these assemblies, thus precluding fuel assembly mis-loading.

9-2

i e

Category 2B fuel assemblies which are required to be placed into a 50% (2 of

4) loading pattern will only be moved into the region 2 area of the fuel pools after the appropriate number of " filler" assemblies needed for this pattern have been qualified and put in place. This clearly identifies the region 2 rack locations that can safely be used for storing these assemblies, thus precluding fuel assembly mis-loading.

Category 2C fuel assemblies which are required to be placed into a 50% (2 of

4) loading pattern will only be moved into the region 2 area of the fuel pools after the appropriate number of cell blocking devices needed for this pattern have been put into place. This clearly identifies the region 2 rack locations that can safely be used for storing these assemblies, thus precluding fuel assembly mis-loading.

Additional misloading protection is provided by the fact that the restricted storage regions will generally be assembled in somewhat isolated areas of the pool such as corners, along walls, or at one end of the pool. Consequently, ongoing need for fuel movement into, out of, or within these areas are also minimized.

When fuel movement in or out of these restricted regions does occur, or if the entire region must be relocated to another area of the pool, quality-verified procedures will be used to direct the actual fuel movements. Such QA-1 procedures, combined with operator awareness and careful visual verification eliminates the need for interlocking devices or special fuel labeling that would prevent inadvertent movement of a filler assembly.

Misplacement of fuel in the 50% checkerboard configuration is highly unlikely due to the visual contrast and the special handling requirements of the cell blocking devices.

IX.5 Pre Staging of Interface Restrictions As summarized in section Vll.3 and discussed in detail in Appendix A, the fuel loading patterns required for fuel categories 1B and 2C have specific restrictions related to the mterfaces that can exist with other loading patterns. These interface restrictions will be accommodated through appropriate orientation of the pre-placed filler assemblies and/or cell blocking devices required for those patterns. Where a category 2C area is not large enough to span across a full module, additional cell blocking devices will be used to create the required empty row of storage cells to sufficiently isolate the area.

Proper identification and placement of fuel assemblies with respect to these categories will occur through administrative review of SNM accountability records, qualification against applicable burnap vs. enrichment curves, and finally through administratively controlled procedures which will govern actual fuel placement, As discussed above, the accountability system to be used for fuel characterization and the existing procedural controls for moving fuel within and between regions, for movement of fuel in and out of the core, and for moving fuel between spent fuel pools will all be retained. Revised burnup vs. enrichment curves which determine fuel category are detailed in the proposed technical specifications found in section VIII.

i 9-3

, - e l

Appendix A Methodology for Development of Region Interface Restrictions ,

A -1

APPENDIX A ItEGION INTEltFACE ItESTitiCTIONS METilODOLOGY This appendix provides supplemental infonnation on the methodology used to establish the necessary interface restrictions for the various fuel storage regions in the McGuire Spent Fuel Pools as discussed in sections Vll and IX of this submittal. The intent of this analysis is to maximize the utilization of the storage cells along these interfaces while ensuring against excessive interaction between these regions.

A.1 Methodology The analysis method that ensures the criticality safety of fuel assemblies in the spent fuel storage rack uses the CSAS25 module contained in the Criticality Analysis Sequence No. 4 (CSAS4). CSAS4, along with the 123GitOUPMTil cross section library are part of the SCALE 3 system of codes. CSAS25 consists of two cross section processing codes 1 (NITAWL and BONAMI) and a 3-D monte earlo code (KENO Va) for calculating the effective multiplication factor for the system. A set of 21 critical experiments has been analyzed using the CSAS25 module with the 123GItOUPMTli library to demonstrate its '

applicability to criticality analysis and to establish a method bias and variability. The experiments analyzed represent a diverse group of water moderated , oxide fuel arrays separated by various materials (stainless steel, Boral, water, etc.) that are representative of LWit fuel shipping and storage conditions, including the McGuire spent fuel pool.

Acceptable interface boundary conditions between storage configurations were detennined by varying the boundaries between various storage regions to determine the worst case configurations for coupling between assemblies in different regions. The boundaries were then reflected to simulate an infinite array. The k err of these infinite boundary arrays were compared to the base ke rr of infinite arrays of either fuel storage region creating the boundary. If the infinite boundary array kerr did not represent an increase in the ke rr of the regions making the boundary, then no storage restrictions were imposed at the interface.

When the worst case did represent an increase, conservative storage restrictions were ,

I applied.

A.2 Assumptions As in most criticality analysis of this type, credit is taken for the inherent absorption in full length structural materials. No burnable poisons, control rods, or supplemental neutron poisons are assumed to be present. All assemblies are assumed to be unirradiated Babcock

& Wilcox (B&W) Mk BW 17X17 fuel with various initial enrichments. Each fuel assembly is treated as a hetemgeneous system with the fuel pins, con'rol rod guide tubes, and instrument guide tube modeled explicitly and the moderator is pure, unborated, full density water.

The base model for all region 2 checkerboard schemes are modeled as groups of four storage locations with the higher enrichment assemblies being modeled in the non-cell locations. The boundaries between checkerboard regions are modeled as small reflected groups in an attempt to detennine worst case coupling configurations between assemblies of differing initial enrichments. The acceptability of various region interface configurations was determined by comparison to the kerr of infinite models of the individual regions which share the boundary.

A-2

A.3 Background "

The present three region configuration for each of the McGuire spent fuel pools does not consider boundary conditions because each region is separated from the others by a minimum of 15 cm of water. The separation between region I and region II is due to a physical gap between the modules. The separation between region Il qualified storage and the checkerboard region containing unqualified fuel is achieved by the Technical Specification requirement to maintain an empty row of cells between the two regions. One of the objectives of this license submittalis the optimization of SFP storage and therefore the elimination of empty rows or empty storage cell requirements.

A.4 Proposed Storage Regions and Boundaries Two of the proposed five storage regions that will be established, will be located within the existing region I rack modules. These will be called regions l A and IB. The other three will be established within the confines of the existing region 2 rack modules and be referred to as region 2A,28, and 2C.

Region l A will allow for the 100% storage of qualified fuel. To be qualified for this

, region, a fuel assembly must have either an initial enrichment no greater than 4.19 weightv, or a minimum burnup as defined by the region l A acceptance curve. This is shown as Curve A in figure A-1. Region IB is made up of those assemblies (up to initial enrichments of 4.75weightfo) not meeting the region l A requirements but still requiring storage in the region 1 rack modules. Region IB assemblies must be stored in a 75% loading configuration with either empty cells or appropriately qualified filler assemblies. This configuration is illustrated in figure A-2. The acceptance criteria for the filler assemblies is shown as Curve 1Bfin figure A-1.

Acceptance curves for region 2A and 2B are also shown in figure A-1 as Curve D and Curve C respectively. Region 2A allows for a 100% storage configuration of fuel with equivalent enrichments of up to 1.5 weight 9c. Assemblies not meeting region 2A requirements will be placed in a region 2B configuration which requires a 50% l checkerboard arrangement with filler assemblies as illustrated in figure A-3. The

, acceptance criteria for the region 2B filler assemblies is shovm as Curve E in figure A-1.

Though none are anticipated from normal operations, fuel assemblies discharged below the acceptance curve for region 2B (i.e. greater than 1.76 weight?. equivalent ) may be stored in ,

either a 50/50 configuration with empty water cells or, if they qualify, as filler fuel ,

assemblies in region IB.  !

The methodology used to generate all of the acceptance curves in figure A-1 is summarized  ;

in section VI and detailed in Appendix B. ,

l l

l l

i A -3

Figure A-1 Acceptance Curves for McGuire Spent Fuel Storage Regions

t. nos.n 2 nw . c . e b n. gen 2 im . curv. D O

f 50-- + Rao.ona ca curv.c k O negeni nier curve B o 40--

• g t nog.n i in . cu,v. A

~ 30--

a

/,/,

? *v ./.

1 4

=

. / ,.>.

O i , ,

p,i +. .

2.00 2.50 3.00 3.50 4.00 4.50 5.00 initial Enrichment (w/o U-23!

l Minimum Acceptance Curve Summary Curve Applicable Region Equivalent Enrichment A Region I A 4.19 weight %

B Region IB Fillers 2.83 weight %

C Region 2I1 1.76 weight %

D Region 2A 1.55 weight %

E Region 211 Filters 0.86 weight %

A - .1

r-er i

I 1

l E

l ri:i:II 2.83 w/o U-235 lil3$ Equiv Fuel

" M 4.75 w/o U-235 M Fresh Fuel

- SS-304 1 l

==== Botaflex Water

'w. . . - -

Fieure A-2 Region IB - Checkerboard Region l A -5 i

~

O l

l l

i I

i l

l j&[$4FJ !IlIE ut::

nummmmm ummmmam 0.86 w/o E

:q:

d;:ie 2:.Idt Ei

{d}m[ Region 2Bhulv U-235 iller Fuel

- 1.76 w/o Equiv U-235 Region 28 Fuel

,- axa

[ikl;g;;ig - SS-304

!kl[

" - Boreflex Water Fieure A3 Region 21150% Checkerboard Configuration with Filler Fuel To analyze the various possible interface configurations, KENO Va models of both spent fuel pool rack designs, including the variations between cell and non cell geometry's of region 2, were developed. The cells (loaded with fuel assemblies of appropriate enrichments) are then arranged in the desired storage configurations.

A -6 l

+ '

A.5 Itegion I lloundaries There is only one possible boundary between fuel storage regions in the itegion I rack modules. As discussed previously, region IB allows for storage of fresh fuel with enrichments in excess of 4.19 weighi%. This region consists of a 75 % (3 of 4) region 1B fuel and 25% region IB filler fuel (1 of 4) checkerboard configuration as shown in figure A-2. For this analysis, region 1B fuel was conservatively modeled as 4.75 weight % fresh fuel. Region 1B filler fuel is defined as fuel that meets the region IB filler acceptance curve (Curve B) shown in figure A-1 which was modeled as 2.83 weight % fresh fuel, if this group of four is repeated periodically the pattern forms alternating rows of 100% 4.75 weight % fuel and mixed rows of 4.75/2.83 weight % fuel in both X and Y directions. This pattern is illustrated in figure A-4 below.

{r 1

fi musumum

- summmme

?!![aF ll -

[I[

1h.

mummmme

3. 2.83 w/o Equiv

$m$$U235 Fuel

> 4.75 w/o Equiv U235 Fuel

- SS-304 y n , y.

[{ @j

- Doraflex i

- - Water l

Figure A-4 Itegion lit floundary Condition The region IB configuration was modeled directly adjacent to the region l A configuration using both region IB row " types" shown above as the interface between the regions.

Criticality analysis using these two models indicated a need to administratively require a row of alternating 2.83 / 4.75 weight % fuel assemblies to be maintained as the boundary.

Based on this requirement, figure A-4 shows the appropriate conditions necessary to create an acceptable boundary between regions I A and 1B.

A-7

e '

A.6 Region 2 Iloundaries The technical specification amendments proposed in this submittal would create the potential for three distinct fuel storage regions in the region 2 rack modules. All possible interfaces between these regions were analyzed to determine the need for interface restrictions.

KENO analysis of adjacent region 2A and 2B fuel loading patterns revealed that no interface restrictions are necessary. Worst case models depicting infinite anays of small islands of the region 2B checkerboard configuration surrounded on four sides by 1.55 weights fuel (region 2A) did not cause a change in the overall ke rr.

Where the interface between regions 2A and 2B are unrestricted, allowing either region to bound the other on all four sides, the calculations reveal a need for restrictions whenever a region 2C loading pattern exists in the spent fuel pool. Specifically, the boundaries between regions 2B and 2C, and between regions 2A and 2C will be restdcted. The required storage restrictions for these two boundary conditions are identical, allowing only one side or two oooosite sides of one region to be bounded by the other. The other two sides must be bound by either the fuel pool wall or an empty row of cells.

The region 2C interface restrictions are illustrated in figure A-5 using adjacent region 2A and 2C configurations as an example. Figure A-5 shows region 2C fuel bounded on two opposite sides by region 2A fuel. A third side is bounded by the fuel pool wall and the fourth side is bounded by empty water cells. Storage restrictions at the interface between region 2B and 2C storage configurations would be identical.

In both of these cases, region 2C was modeled as some number of rows (infinite in the Y direction) bounded on two opposite sides by some other number of rows (also infinite in the Y dire-etion) of region 2A and 2B fuel. Each boundary condition also includes an analysis of the two sides being bounded by concrete to simulate the fuel pool walls. The empty row of cells serving as a boundary was not explicitly modeled since it was judged to represent an infinite water path that would prevent neutron interaction.

l I

l A-8

I s

Region 2A Region 2C

$ i li Ab Region 2A Fuel

""u' h

~""" -

? Region 2C Fuel SS-304 muuuunu

- Doraflex Water ih;: W,4 ;_

_e i d - ,

Nh Fuel Pool Wall Ficure A-5 Restrictions for Region 2A - 2C Interface A.7 Conclusions This appendix documents the interface restrictions required between the five regions of-spent fuel storage that will be instituted in the McGuire spent fuel pool. The CSAS25 module in the SCALE 3 system of codes was used to determine the necessary loading restrictions. CSAS25 utilizes the 123GROUPGMTH cross sectional library, Nitawl and Bonami as cross section processors, and Keno Va to determine the kerr of a given interface configuration.

A-9

t i

e Acceptable interface configurations were determined by varying the boundaries between i various storage regions and reflecting these boundaries to simulate an infinite array. The kerrof these infinite boundary arrays were compared to the baseek rr ofinfinite arrays of the individual fuel storage regions being assessed. If the infinite interface array did not represent an increase in Keff, then no interface loading restrictions were imposed. For those boundaries that do carry restriction;, the governing criteria were 1) to assure that no increase in the nominal k err is created at the boundary, and 2) to allow for the most flexibility in the building of regions and boundaries and thus promote the optimization of spent fuel storage. A summary of the resulting interface restrictions are provided in Table A-1 below.

l Table A-1 Summary of Region Interface 1.oading Restrictions  ;

Interface Restrictions Row of region 1B bounding region l A must Region I A and 1B be a row of alternating region 1B fuel types and regionlB fillerlocations.

Region 2A and 2B No Interface Restrictions  :

Region 2A or 2B At least 2 opposite sides of region 2C shall be  ;

bounded by either a row of empty water cells -

and 2C or the fuel pool wall. The remaining side (s) may be either region 2A or region 2B or both.

A - 10

I i

, i i

[

Appendix B Methodology l for Burnuo Credit Analysis 1

1 l

B-1

, 2 APPENDIX B METHODOLOGY FOR BURNUP CREDIT ANALYSIS H.1 Nominal Reactivity Calculation The methodology for burnup credit analysis starts with the fuel storage rack drawings to construct a predictive computer model. This model in the form of an input deck calculates the reactivity level of the desired fuel storage configuration for the racks. As an example for this appendix, a 100% fuel loading storage configuration from Duke Power Company's McGuire Region 1 storage racks is analyzed. The 100% loading configuration places a fuel assembly in every storage location without the use of ny checker boarding scheme that requires empty cells (water-holes) or depleted (filler) f uei assemblies.

Table B-1 below provides typical nominal K-effective values for fuel with varying initial enrichments stored in the 100% loading configuration. The reactivity of the storage ,

I configuration is shown as a function of increasing amounts of burnup. The curves are generated through in-core depletion of the applicable fuel assembly using CASMO followed by storage rack-specific analysis of the depleted fuel. CASMO models an infinite array of a single fuel type. SIMULATE must be used if dissimilar fuel assemblies are ,

analyzed, as is the case for the more complex storage configurations discussed in section J 5.0 of this appendix. Both CASMO and SIMULATE compute reactivity versus burnup.

l Table B-1 Nominal Reactisity of Region 1 Fuel Racks with 100 % Storage Configuration Burnup Kmax 4.0 w/o 4.2 w/o 4.5 w/o 4.75w/o 5.0 w/o 0 0.92918 0.92053 0.92942 0.94166 0.95098 0.95961 5 0.92516 0.88297 0.89218 0.90512 0.91487 0.92394 10 0.92114 0.84895 0.85878 0.87255 0.88303 0.89279 15 0.91784 0.81638 0.82674 0.84126 0.85243 0.6288 l 20 0.91739 0.78524 0.79612 0.81146 0.82328 0.83423 25 0.91694 0.75618 0.76748 0.78343 0.79581 0.80743 30 0.91649 0.72742 0.73912 0.75567 0.76859 0.78084 35 0.91604 0.69961 0.71158 0.728M 0.74203 0.75445 40 0.91560 0.67245 0.68446 0.70180 0.71556 0.72883 45 0.91515 0.64M3 0.65828 0.67582 0.68974 0.70293 50 0.91470 0.62192 0.63336 0.65039 0.6M22 0.67785 55 0.91425 0.59921 0.61004 0.62635 Of>4004 0.65316 60 0.91380 0.57870 0.58860 0.60390 0.61682 0.62988 Table B-1 provides the data to construct a reactivity versus burnup plot for each of the analyzed enrichment values. Once the fuel depletion data is calculated, generation of the desired fuel storage qualification curve requires a rack-specific maximum reactivity curve as represented by the Kmax column in Table B-1.

B-2

A o 1 B.2 Biases And Uncertainties Generation of a rack specific maximum reactivity curve requires the computation of I many biases and uncertainties. The maximum reactivity curve is calculated by subtracting l the required biases and uncertainties from the regulatory reactivity limit for fuel storage

( Kerr = 0.95 for spent fuel storage) as is shown in the equation below.

Kmax = K reg lim - AK Through the summing of the biases and uncertainties, the maximum reactivity as a function of burnup can be plotted for each desired storage configuration. Table B-2 lists typical new fuel biases and uncertainties which must be considered. The methodology bias and uncertainty are independent of rack design. The mechanical uncertainty is rack I

specific and must be re-calculated for each storage rack analyzed. The Boraflex shrinkage and self-shielding values are computed based the amount of Boraflex in a rack and are rack specific.

Table 11-2 Typical New Fuel liiases and Uncertainties Bias or Uncertainty AK A Keb Methodology Bias -0.00189 AKs b Boraflex width shrinkage Bias 0.00417 A Kss Self-Shielding Bias 0.00150 A K bsa Borallex axial shrinkage Uncertainty 0.00138 A Keu 95/95 Methodology Uncertainty 0.01080 A Kme Mechanical Uncertainty 0.01311 B.2.1 Methodology Bias and 95/95 Methodology Uncertainty The results for the criticality methodology are validated by comparison to measured results of fuel storage critical experiments. The criticality experiments used to benchmark the methodology were the Babcock and Wilcox close proximity storage critical experiments performed at the CX-10 facility. The B&W critical experiments used are specifically designed for benchmarking reactivity calculation techniques. The experiments are analyzed, and the statistical accuracy of the calculated reactivity results are assessed. The integral transport theory code CASMO-3, a data processing code TABLES-3, and the nodal diffusion theory code SIMULATE-3 are used to analyze the experimental configurations from a criticality standpoint.

B-3

'4 9

f The criticality experiments examined have similar nuclear characteristics to spent fuel storage and are applicable to conditions encountered during the handling of LWR fuel outside reactors. Table B-3 shows a typical calculational uncertainty and code bias for the CASMO3/ TABLES 3/ SIMULATE 3 methodology when applied to fuel storage

) calculations.

Table 11-3 Typical Benchmark Results and Uncertainties Standard Deviation 0.00371 95/95 One-Sided Tolerance Factor 2.911 95/95 Methodology Uncertainty 0.01080 Methodology Bias -0.00189 The methodology uncertainty for the experiments is calculated by multiplying the standard deviation times the 95/95 one sided tolerance factor. There are no significant '

trends in the results with respect to moderator soluble boron concentration, array spacing, cr boron level in the isolation sheets as shown in Table B-4.

B-4

M Table B-4 CASM03/ TABLES 3/S!MULATE3 Benchmarking Results Core Soluble Moderator Separation Poison Ki calc K meas Hias Boron Temp Spacing Sheet (%B)

(cm) 2 1037 18.5 0 n/a 1.00280 1.0001 -0.00270 3 764 18 1.636 n/a 1.00337 1.0000 -0.00337 9 0 17.5 6.544 n/a 1.00091 1.0030 0.00209 10 143 24.5 4.908 n/a 0.99933 1.0001 0.00077 11 514 26 1.636 SS 1.00525 1.0000 -0.00525 l 13 15 20 1.636 1.614 1.00914 1.0000 -0.00914 l 14 92 18 1.636 1.257 1.00470 1.0001 -0.00460 395 15 18 1.636 0.401 0.99627 0.9988 0.00253 17 487 17.5 1.636 0.242 0.99911 1.0000 0.00089 19 634 17.5 1.636 0.1 1.00030 1.0002 -0.00010 avg K-calc 1.00212 st.dev calc 0.00371 ave Kmeas 1.00023 avn bias -0.00189 A further indication of the accuracy of the process comes from comparisons to the results of other benchmarking elforts of the same experiments. The calculated uncertainty and bias of the code, compares favorably with values presented in other calculations as shown in Table B-5.

Table B-5 Comparative Bench marking Results Duke YAEC YAl:C Duke YAEC Core Cas/Sim Cas/Sim Cas/PDQ Keno IV Keno IV 2 1.00280 1.00284 1.00325 1.0011 +"

0.0038 1.00085 +" O.00294 3 1.00337 1.00335 1.00622 0.9987 +'- 0.0038 0.99886 +'- 0.00336 9 1.00091 0.99813 1.00192 0.9869 +" 0.0046 0.99116 +/- 0.00365 10 0.99933 0.99823 1.00612 0.9862 +'- 0.0049 0.98551 + ' - 0.00362 11 1.00525 1.00245 1.00562 1.0062 +'- 0.0039 1.00673 +'- 0.00360 13 1.00914 1.00313 1.00208 1.003 6 + " 0.0054 1.01049 +'- 0.00402 14 1.00470 0.99882 0.99863 0.9960 +'- 0.0040 1.00544 +'- 0.00367 15 0.99627 0.99250 0.99381 0.9919 + '- 0.0037 0.99344 +'- 0.00344 17 0.99911 0.99569 0.99740 0.9978 +" 0.0040 1.00272 +'- 0.00314 19 1.00030 0.99689 0.99879 0.9929 +'- 0.0040 0.99591 +'- 0.00276 K -avg 1.00212 0.99920 1.00138 0.9955 0.99911 St dev 0.00371 0.00367 0.00416 0.0065 0.0065 B-5

h B.2.2 Bornflex Width Shrinkage Bias and Borallex Asial Shrinkage Uncertainty Special neutron pc. Mon verification testing was perfomied on irradiated fuel storage racks.

The testing process accuracy was verified using a special mock fuel storage cell specirilly designed for benchmark testing purposes. The benchmark testing data was evaluated using standard statistical methods. The test process instrumental bias and uncertainty was established, and the test data results were evaluated statistically.

Based on the above verification testing, the nominal and worst case Boraflex shrinkage conditions in the storage racks were established. These values included the test process bias and uncertainty. Fuel storage array reactivity impacts were evaluated using sensitivity studies performed by the rack manufacturer.

11.2.3 Self Shielding Ilias This bias accounts for the Boron Carbide (B4 C) particulate self shielding effects that result when either SCALE / KENO or CASMO/ SIMULATE methodology are used in analyzing the criticality of fuel storage racks. The rack poison material (Boraflex) is made up of B 4C particles suspended in a silicate binding. Both methodologies assume that the B4C is homogenized within the Boraflex. This approximation neglects the self shielding effects caused by the B 4C particles and causes the codes to over predict the worth of the poison sheets. Therefore, the approximation introduces a non-conservative element in the calculation.

To quantify the non-conservative element, a total of four self shielding factors are calculated as a function of energy. These factors were then used to determine four separate changes in the neutron transmission probabilities (DPT ) through the sheets caused by self shielding effects. These DP Ts were then converted to biases using the reaction rates in the Boraflex along with the worth of the Boraflex sheets.

B.2.4 Mechanical Uncertainty The mechanical uncertainty calculation considers those elements of the model which can vary from the stated design value to the actual manufactured value. Parameters which must be considered are fuel assembly center to center (CTC) spacing, canister envelop, fixed poison width, fixed poison thickness, fuel stack density, and fuel enrichment.

Criticality calculations are made at both the maximum and minimum values of each parameter. The difference between the maximum and minimum values is averaged. The final value for the mechanical uncertainty is the root sum of squares of these averages.

B-6

a B.2.5 Combination of New Fuel Biases and Uncertainties Once the new fuel biases and uncertainties are known, they are combined in the following i equations to determine an aggregate value. l l

l AKeff = AKch+0Nbs + AK3s + (AKbsa + ( AKmu) +(AKme) 1 Typical Values:

AK,77 = - 0.00189 + 0.00417 + 0.00150 + (0.00138)2 +(0.01080)2 + (0.01311)

AK,77 = 0.020822 In addition to the new fuel biases and uncertainties, there is also an added bias and uncertainty associated with fuel burnup. Therefore, the final equation for the pool reactivity limit is written as a function of burnup.

11.2.6 Burnup Bias and Uncertrinty A value for the burnup uncertainty end bias is required to quantify the reactivity of burned nuclear fuel assemblies. Table B-6 shows the magnitude of two typical burnup uncertainties associated with using CASMO3 / TABLES 3 / SIMULATE 3 for criticality analysis.

Table 11-6 Ilurnup Uncertainty aKr, m.ne nvwt w + ,, 0.00us a K nn m w,,., pm..wv tw+v 0.01 The first penalty accounts for uncertainties in the reactivity due to uncertainties in the burnup of the assembly, while the second penalty accounts for the reactivity holddown effect oflumped barnable absorbers.

The exposure reactivity uncertainty accounts for the uncertainty on the assembly burnup.

Since the final burnup qualification curves provided in the new Technical Specifications are based on a code calculated burnup, the uncertainty in that calculated burnup must be considered. Rather than determining the uncertainty on the actual burnup, the uncertainty on reactivity due to burnup was applied to account for the burnup uncertainty. Reactivity H-7 l

, n l

measurements are performed at the plant and compared to predictions on a regular basis. l The comparisons determine the errror in the predicted versus actual reactivity of the core l at hot full power conditions. The results of these comparisons were tabulated for 18 l cycles of Duke Power operating experience for a total of 259 data points. This collection 1 of data covers a wide range of burnups. A 95/95 one-sided tolerance was applied to this 1 data to determine the maximum reactivity error associated with the burnup of the fuel. I Since this represents the maximum error due to burnup, this penalty is applied as a function of burnup. Beyond this value, the full penalty is applied. The maximum reactivity equation then combines the regulatory reactivi:y limit for fuel storage with the new fuel and bumup biases and uncertainties as shown below.

Two other variables considered in developing this methodology were the axial burnup profile which exists in varying magnitudes as a result of reduced neutron flux at the top and bottom portions of the core, and the effects of having fuel inserts (i.e. burnable poison rods, control rods, etc.) present in the assemblies. Preliminary assessment of the axial burnup profile indicated this to be a very insignificant impact on the burnups required for qualification. With respect to the fuel insert concern, despite the reduction in available B-10, the reduced moderator creates a more dominant effect at the boron concentrations typical for the MNS station. Consequently, preliminary analyses actually indicate a reduced reactivity effect caused by the components. As a result of these preliminary assessments, no additional biases or uncertainties were included in the final analyses or in th resulting burnup requirements guidelines.

Two pool maximum reactivity equations are required because of the effect of lumped burnable poisons (LBP). The pulling of a LBP after a given burnup creates a one time reactivity insertion. To compensate for the added reactivity, a penalty of 0.01 is added to the maximum reactivity equation. The application of this penalty is applied as a function  ;

of burnup until a pre-determined limit is attained, typically 14 GWD/MTU. Beyond this value, the full penalty is applied. The maximum reactivity equation then combines the regulatory reactivity limit for fuel storage with the new fuel and burnup biases and urcertainties as shown in section B.3 on the next page.

I B-8 1

)

I l

I l

B.3 Maximum Enrichment Curve - Burnup vs. Reactivity The equations shown below represent the behavior of the maximum enrichment for two separate burnup ranges. When plotted together, they provide the maximum enrichment f curve for the chosen storage configuration and rack design.

Kmax = Regulatory Pool Limit -(New Fuel liiases + Uncertainties)

-(llurnup liiases + Uncertainties) l (For Burnup S14 Glt'DIMTU) . I Kmax = 0.95 -(0.02082)-

urn- up _0.6 Burn - up i 50 14 Kmax = 0.92918 -

.

• B urn - up _0.Ol

• Ilurn - up  ;

50 14 i

(For 14 < Burnup < 50 GIVDIMTUJ .

K max = 0.95 -(0.02082) 0.00448*11 urn-up 0.01 K max = 0.91918 0.NMurn- up 50 The above equations when plotted together provide the maximum enrichment curve for l

the chosen storage configuration and rack design. The multiple fuel depletion curves with I the maximum enrichment curve are shown in Figure B-1 on the following page. The intersection of the curves provides data points for generating a burnup versus enrichment cun e.

l l

l l

1 l

\

B-9 f - _ - - - - - - - - - - - - - - - - - _ - - - _ - - _ _ _ _ _

/

, 'D Eigure n 1 Maximum Enrichment and Fuel Burnup Curves 0.9 5 --

• 4 8 "'

3 0.941 5 0.93 a 0 4 2 w/o j 0.92 x  % ~.- .- . . . , = . s w,o

" 0.91 -- ,

5 0 w'o 0.9 , , , .l l l l 0 10 20 30 40 50 60 B u rn-u p of Feeder Assembly (GWD/MTL B.4 Qualification Curve - Burnup vs. Initial Enrichment The next part of the process is the generation of a burnup versus initial enrichment curve.

The solution for the intersection of the curves in Figure B-1 is performed by taking the maximum reactivity equations and solving them simultaneously with the linear regressions of the fuel specific depletion curves. To eliminate the effect of the non-linearities of the curves, the range of the linear regression is reduced to include only the two or three points that surround the intersecting curve.The number of points depends on the distribution. Usually only two points are required; however, if one of the points falls very close to the intersection point, then an additional point is added to compensate for the unevenness in the spread. The solution of the system of simultaneous equations provides the data for the qualification curve which is plotted in Figure B-2 below.

Il - 10

i Fieure B-2  ;

l Qualification Curve for 100% Storage Configuration l

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f The curve in Figure B-2 show the minimum amount of burnup required to qualify fuel for ,

storage as a function of the fuel's initial enrichment. A fuel assembly qualifies if it falls.  !

above the curve for that storage configuration. ,

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B.5 Generation of Multiple Qualification Curves The need to store unqualified, highly reactive, fuel assemblies or the need for additional storage flexibility requires the use of multiple storage configurations. Additional storage configurations require multiple qualification curves.

The example in Figure B-2 has an upper enrichment limit of 4.19 w/o for fresh fuel. In order to store fuel enrichment higher than 4.19 w/o, a checkerboard loading pattern is required. The premise behind the checkerboard loading configuration is that unqualified (high reactivity) fuel assemblies can be stored with less reactive (filler) fuel assemblies so that the combined reactivity meets storage qualification requirements.

Checkerboarding patterns can use either one or two filler assemblies in a group of four storage cells. For this example a 75 % checkerboard is studied where one filler is used with three high reactivity fuel assemblies.

The same process used to generate the 100 % s:orage configuration quali0 cation curve is used to produce the filler qualification curve. The same CASMO computer model is used; however, SIMULATE must be used to pair different fuel assemblies into a combined reactivity calculation. In order to generate the filler qualification curve, a multi-step process must be followed which is detailed below.

1) Select the most reactive unqualified fuel type which must be stored (e.g.4.75 w/o fresh fuel).

2) Calculate the amount of bumup required for the filler assembly, ,

so that when grouped with the high reactivity fuel assemblies, the net reactivity meets the rack reactivity qualifications. This is l done by performing multiple SIMULATE runs with increasing amounts of burnup on the filler assembly.3 12123) A linear regression on the reactivity values is performed for the combination of the high reactivity and filler fuel assemblies. As before, the regression equation is solved simultaneously with the rack maximum reactivity curve. The equation solutions are the data for the filler qualification curve.

The process can be followed multiple times to accommodate variable storage rack designs (i.e. two region pools) and variable storage configurations. All of the desired qualification curves are then plotted on the same chart to produce the final storage rack qualification curves. Figure B-3 on the following page illustrates a full set of qualification curves for a two-region storage pool utilizing unrestricted (100%) and restricted (use of filler assemblies) storage configurations in each region.

3 SIMULATE is used to calculate the reactivity for a group of assemblics. The base model for the SIMULATE checkerboard calculations is a group of four assemblics and supporting rack elements. The geometry is infinitely renected with periodic boundary conditions.

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Figure B-3 ,

Qual!(ication Curve for Multiple Storage Configurations i Region 2 Fliier Curve E O Region 2100% Curv. D m

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