ML20092K209

Application for Amend to License NPF-86,changing TS 3/4.9.1 Re Refueling Boron Concentration (Ref NUREG-1431)

ML20092K209
Person / Time
Site:	Seabrook
Issue date:	09/20/1995
From:	Feigenbaum T NORTH ATLANTIC ENERGY SERVICE CORP. (NAESCO)
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20092K214	List: ML20092K209 ML20092K220
References
RTR-NUREG-1431 NYN-95074, NUDOCS 9509250279
Download: ML20092K209 (5)

Text

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North Atlantic Energy Service Corporation i

9 Nor(L11 p.O. ,,, 300 h

Atlantic Seabrook, NII O3874 (603) 474-9521, Fax (603) 474-2987 The Northeast Utilities System Ted C. Feigenbaum Seni r Vice President & i NYN- 95074 Chief Nuclear Officer September 20,1995 {

United States Nuclear Regulatory Commission Washington, D.C. 20555 Attention: Document Control Desk

Reference:

. Facility Operating License No. NPF-86, Docket No. 50-443

Subject:

Change to Technical Specification Bases Section 3/4.9.1, Refueling Boron Concentration Gentlemen:

This letter transmits changes to the Seabrook Station Unit No.1 Technical Specification Bases for the Refueling Boron Concentration (Bases Section 3/4.9.1). The changes were made pursuant to the requirements of 10 CFR 50.59, and are being provided for the Staffs information. The changes to Bases Section 3/4.9.1 were made to incorporate a slightly modified version of the Bases discussion in Revision 1  ;

of NUREG 1431, Westinghouse Standard Technical Specifications. The purpose of this Technical  ;

Specification Bases change is to provide enhanced Bases utilizing NUREG-1431 " Standard Technical i Specifications Westinghouse Plants," for Technical Specification 3.9.1, " Boron Concentration" and the ,

related MODE 6 Technical Specifications. j Should you have any questions regarding this letter, please contact Mr. James M. Peschel,  ;

Regulatory Compliance Manager, at (603) 474-9521, extension 3772.

Very rulyyours,

/p na V Ted C. Feigen%

TCF:jmpjr/sm Enclosure l ctm a .

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i 9509250279 950920 PDR ADOCK 05000443

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4 bnited States Nuclear Regulatory Commission = . September 20,1995 Attention: Document Control Desk . Page two P

cc: . Mr. Thomas T. Martin '  ;

Regional Administrator  !

U.S. Nuclear Regulatory Commission Region I  ;

475 Allendale Road King of Prussia, PA 19406 -

Mr. Albert W. De Agazio, Sr. Project Manager Project Directorate I-4 l Division of Reactor Projects U.S. Nuclear Regulatory Commission Washington, D.C. 20555 Mr. John Macdonald NRC Senior Resident Insgator

.P.O. Box 1149 Seabrook,NH 03874 Mr. George L. Iverson, Director r New Hampshire Office of Emergency Management 107 Pleasant Street '

Concord,NH 03301

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L INTRODUCTION AND ANALYSIS / EVALUATION OF PROPOSED CHANGES A' . Introdmetion ]

The purpose of this Technical Specification Bases change is to provide enhanced Bases, utilizing the -

! guidance of NUREG-1431 Revision 1, Westinghouse Standard Technical Specifications, dated April 7, 11995. It is the intent that the Bases change provided in Section IV will also clarify the limitations on

" positive reactivity changes" in ACTION statements for Technical Specifications applicable in Mode 6;

- B. Analysin/ Evaluation The safety analysis for boron dilution events assume an initial RCS boron concentration which is equal to  ;

- the refueling boron concentration. During refueling the RWST is drained to fill the refueling volumes. ,

- There are also Technical Specifications that impose limitations on ." positive reactivity changes" in certain

- circumstances. It is the position of this Bases change that transferring water to the refueling volumes that is -

' borated to ' greater than or equal to the refueling boron concentration is acceptable because it will ensure the reactor remains suberitical in accordance with the Bases for this Technical Specification. Likewise, lower  :

temperature water may be added to the refueling cavity. Thus, for example, operations with the plant in Mode 6 such as, the flooding of the refueling volumes with water supplied from the .RWST is acceptable provided that the RWST boron concentration is greater than or equal to the required refueling boron concentration.

The attached Bases change provides a general background on boron concentration as it applies during refueling operations. Specifically, the boron concentration ensures the more restrictive of the following reactivity conditions are met:

1. A k eg of 0.95 or less, or

- 2. A boron concentration of greater than or equal to 2000 ppm The attached Bases change provides a discussion of applicable safety analyses. It states that the reactivity I condition of the core is consistent with the initial conditions assumed for the boron dilution accident in the accident analysis and is conservative for Mode 6. It also states that during refueling, the water volume in the spent fuel pool, the transfer canal, and the reactor vessel form a single mass. As a result, the soluble boron concentration is relatively the same in each of these volumes.

The attached Bases change also describes that CORE ALTERATIONS and positive reactivity changes f i

(including actions to reduce boron concentration) are contingent upon maintaining the unit in compliance with the LCO. His means that borated water being added to the refueling volumes of a lower boron j l* . concentration than contained in these volumes is acceptable provided that the most restrictive of k,g 5; 0.95 i or the specified refueling boron concentration is maintained. This is acceptable because the Bases change states that positive reactivity changes are contingent upon maintaining the unit in compliance with the LCO.  ;

The attached Bases change also states that the temperature of water added to the refueling volumes can be lower than the temperature in those volumes (within the ope 6 ability limits of the RWST in Mode 6). This is acceptable because the accident analyses in Mode 6 are based on maintaining the refueling boron C concentration.

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t I 'Ihe Updated Safety Analysis Report (UFSAR) Section 914 describes the refueling operations and I

discusses significant points associated with the operation. In general, the preparations for refueling operations include borating and cooling down the Reactor Coolant System as required by Technical i

! Specifications. Specifically, the UFSAR describes that refueling procedures will include a step that requires I that the refueling water and reactor coolant contains greater than or equal to the refueling boron concentration. His concentration, together with the negative reactivity of control rods, is sufficient to keep  ;

L the core approximately 5% Ak/k suberitical during the refueling operations. It is also sufficient to maintain 1

- the core subcritical in the unlikely event that all of the Rod Cluster Control Assemblies are removed from l the core.

i The UFSAR Chapter 15, Section 4, describes postulated faults which could result in reactivity and power - _

distribution anomalies. Section 15.4.6.1 specifically describes credible scenarios by which the reactor ,

i coolant system boron concentration may be inadvertently reduced to the point where shutdown reactivity  ;

may be challenged. The boron dilution event is classified as an ANS Condition 11 incident, a fault of .

moderate frequency.

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. The dilution analysis for refueling operations assumes initial conditions for RCS boron concentration. The

!. initial conditions are included in the safety analysis for each operating cycle and these initial conditions l conservatively assumes a maximum boron concentration to lose all shutdown margin, which is also well below the refueling boron concentration. The results of these analyses conclude that for a dilution event  !

during refueling, sufficient time is available from when the shutdown monitor alarm actuates until a loss of  :

, shutdown margin exists. During this time control room operators will be alerted of such a condition and l allowed sufficient time to intervene.

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II. PROPOSED SCHFDULE FOR ISSUANCE l North Atlantic requests NRC issuance of the changes to Technical Specification Bases 3/4.9.1 by November 1,1995 in support of the upcoming refueling outage. i i

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b. i HL' MARKUP OF PROPOSED CHANGES j

f i  ; The enclosed markup pages reflect the currently issued version of Technical Specification Bases.  !

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