ML20204H649

Proposed Tech Specs,Reflecting Revised Design Features to Generally Allow Use of Modified Fuel Assemblies in Core

ML20204H649
Person / Time
Site:	Mcguire, McGuire
Issue date:	08/04/1986
From:	DUKE POWER CO.
To:
Shared Package
ML20204H627	List: ML20204H624 ML20204H649 ML20204H655
References
TAC-61512, TAC-61513, NUDOCS 8608080170
Download: ML20204H649 (4)

Text

ATTACHMENT 1 ADDITIONAL PROPOSED McGUIRE UNIT 1 AND 2 TECHNICAL SPECIFICATION CHANGES l

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l DESIGN FEATURES

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5.2.1.2 REACTORBUJJOING

a. Nominal annular spece = 5 feet.

b. Annulus nominal volume = 427,000 cubic feet.  !

c. Nominal outside height (measured from top of foundation base to the top of the done) = 177 feet.

d. Nominal inside diameter = 125 feet.

e. Cylinder wall minimum thickness = 3 feet,

f. Dome minimum thickness = 2.25 feet.

g. Dome inside radius = 87 feet. '

DESIGN PRESSURE AND TEMPERATURE 5.2.2 The reactor containment is designed and shall be maintained for a -

maximum internal pressure of 15.0 psig and a temperature of 250*F.

R00 LOLATICH5 Psatl ROO LOLAfrows hay AT Any reht OsentA 5.3 REACTOR CORE d"

n'ur co*,"e>~n ri.~ oe :**;

8Y "'# " *** d"d'Y's a) ;. d 5 8"'d*",e"s.'"n o wornaos zinces.y 'c*u'd ss,1)pos.sg4 ,

Roos FAgnscA rts FAan zincasey.'t en IthfuLiss jrtgy, og 3)ygg4,,g,g3 5.3.1 The core shal contain 193 fuel assemblies with each fuel assembly containing 264 fuel ced. : :d with Ifr::le, ?. Each fuel rod shall have a l nominal active fuel length of 144 inches and contain a maximum total weight of l 1766 grams uranium. Th: '-ft 4' ::r: 10: ding :h:11 ran e xb_ ;;rkt .;nt

.c' O. 2 r ight ;:r::nt U-? E Reload fuel shall be aimilar in physical design to the initial core loading and shall have a maximum enrichment of 3.5 weight percent U-235.

CONTROL ROD ASSEMBLIES 5.3.2 The core shall contain 53 full-length and no part-length control rod assemblies. .The full-length control rod assemblies shall contain a nominal 142 inches of absorber material. The nominal values of absorber material for Unit I control rods shall be 80% silver,15% indium, and 5% cadmium. The nominal values of absorber material for Unit 2 control rods shall be 100%

boron carbide (B.C) for 102 inches and 80% silver, 15% indium, and 5% cadmium for the 40-inch tip. All control rods shall be clad with stainless steel tubing.

McGUIRE - UNITS 1 and 2 5-6 A s s u o m e u r reo. 6.~Ir o AMGWOM6MTWo n l wor 1)

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ATTACHMENT 2 JUSTIFICATION AND SAFETY ANALYSIS

, Mr. H.B. Tucker's (DPC) May 15, 1986 letter (as supplemented via letters dated May 23, June 6, June 30, and July 10, 1986) presented a justification and safety analysis for a proposed McGuire Unit 1/ Cycle 4 Core Reload and attendant RAOC and positive moderator temperature coefficient technical specification changes,

concluding that the proposed Cycle 4 design did not cause the previously acceptable safety limits to be exceeded and that the technical specification 1 changes ensured plant operation consistent with the design and safety evaluation conclusion statements made in the Cycle 4 Reload Safety Evaluation (RSE).and that i

these conclusions remain valid. However, inspections during Cycle 3/4 refueling operations revealed damage to a fuel assembly. It was postulated that a contributing factor to this damage may have been flow through baffle joints impinging on rods resulting in induced vibration and subsequent damage to several fuel rods. As a result, it was decided to redesign the core without the damaged assembly. The core loading pattern was altered and two partially irradiated fuel assemblies were modified for insertion in the location previously occupied by the damaged fuel assembly and another location where baffle gap measurements approximate those in the damaged assembly's location. The modifications increase

the assemblies resistance to flow impingement through baffle joints and thereby 4

reduce the potential for fuel damage. The modified assemblies contain solid stainless steel rods and open water channels in place of certain fuel rods (note that one of the two assemblies modified is a demonstration assembly that has been in the Unit 1 core since Cycle 2 and already contained 1 open water channel as documented in previous RSE's). A meeting between the NRC, Duke Power Company, and-

! Westinghouse was held on August 1,1986 in which this situation was discussed in detail.

i Attachment 2A is Revision 1 of the cycle-specific reload safety evaluation for McGuire Unit 1/ Cycle 4. This RSE has been updated to include all changes and additions (denoted by bars in the right margin) necessitated by the core redesign.

The revised RSE presents an evaluation for McGuire Unit 1, Cycle 4, which demonstrates that the redesigned core reload will not adversely affect the safety

). of the plant. All of the accidents analyzed and presented in the FSAR which could

! potentially be affected by this change have been reviewed for the Cycle 4 design j to determine the impact on the Cycle 4 core performance and it is concluded that j the operation of the core containing the modified fuel assemblies does not cause

the previously acceptable safety limits for Cycle 4 to be exceeded. (Note that the NRC has previously reviewed and approved similar type modifications on Trojan Nuclear Plant (amendment No. 45 to NPF-1), and is currently reviewing a request on Beaver Valley Power Station Unit No. 1 (ref. Duquesne Light letter to NRC/0NRR dated July 11, 1986). In addition, McGuire Unit I has been operated with a water hole in an assembly during the 2 previous cycles). Consequently the previously proposed RAOC and positive MTC Technical Specification changes remain acceptable

! (note that the proposed application of the positive MTC Technical Specification l change to McGuire Unit 2 is unaffected by this Unit 1/ Cycle 4 core redesign and

consequently its justification and safety analysis remains valid). However, since j the two modified fuel assemblies now contain 255 and 256 fuel rods respectively 2

instead of 264 as described in the design features section of the technical i specifications, an additional technical specification change is needed.

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Attachment 2 Page 2 Accordingly, Technical Specification 5.3.1 is reworded to generally allow certain modifications to fuel assemblies involving the fuel rod locations providing they are determined acceptable by cycle-specific reload analysis. This enables the specification to better describe the various potential fuel assemblies that could be shown acceptable for utilization in the reactor core (note that this rewording is also being proposed for McGuire Unit 2 since the McGuire Unit 1 and 2 Technical Specifications are combined - this would allow for similar modifications to be made on McGuire Unit 2 as necessary). The relaxing of the 264 fuel rods per assembly requirement is justificable in that 264 fuel rods is the " normal" complement in an assembly, although certain differing configurations can be shown to be acceptable through safety analyses. The specific fuel assembly modifications performed for McGuire 1/ Cycle 4 have been determined acceptable by the attached revised McGuire 1/ Cycle 4 RSE in accordance with the provisions of this proposed specification. In addition to the above mentioned rewording, a sentence in the specification addressing the maximum enrichment of the initial core loading is being deleted in view of its obsolescence since Unit 1 is currently on its fourth core loading (again, this is also being proposed for McGuire Unit 2 since the McGuire Unit 1 and 2 Technical Specifications are combined and Unit 2 is currently operating with its third core loading).

In conclusion, the safety of the plant remains unadversely affected by the

redesigned core reload, and the proposed technical specification changes ensure that plant operation remains consistent with the design and safety evaluation conclusions and that these conclusions remain valid.

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