ML20100G236

Application for Amends to Licenses NPF-4 & NPF-7,changing Tech Specs to Reduce Min Number of Thimbles to Obtain Flux Map for Routine Monthly Surveillance of Hot Channel Factors. VEP-NOS-8, Study of Reduced Number..., Encl.Fee Paid

ML20100G236
Person / Time
Site:	North Anna
Issue date:	04/01/1985
From:	Stewart W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	Harold Denton, John Miller Office of Nuclear Reactor Regulation
Shared Package
ML20100G237	List: ML20100G236 ML20100G245 ML20100G262
References
85-074, 85-74, NUDOCS 8504080125
Download: ML20100G236 (4)

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1985 VNtGINIA POWER Mr. Harold R. Denton, Director Serial No.85-074 Office of Nuclear Reactor Regulation N0/ESH: dao Attn:

Mr. James R. Miller, Chief Docket Nos. 50-338 Operating Reactors Branch No. 3 50-339 Division of Licensing License Nos. NPF-4 U. S. Nuclear Regulatory Commission NFP-7 Washington, D. C. 20555 Gentlemen:

VIRGINIA POWER NORTH ANNA POWER STATION UNIT NOS. 1 AND 2 PROPOSED TECHNICAL SPECIFICATION CHANGES Pursuant to 10 CFR 50.90, Virginia Power requests an amendment in the form of changes to the Technical Specifications to Operating Licenses NPF-4 and NPF-7, for North Anna Unit Nos. I and 2.

The proposed Technical Specification changes will reduce the minimum number of thimbles from 38 to 26 thimbles, to obtain a flux map for routine monthly surveillance of hot channel factors. A reduced number of thimbles flux map will only be allowed when 38 thimbles cannot be obtained due to thimble blockage, or inoperable movable incore detector equipment. A reduced number of thimbles flux map can only be used to verify hot channel factors for monthly surveillance, and additional uncertainties will be applied to the measured hot channel factors to ensure compliance with their Technical Specification limits.

The proposed changes will not adversely affect the safe operation of the plant since all hot channel factors will be within their Technical Specification limits. The proposed Technical Specification changes for North Anna Unit 1 are provided in Attachment 1.

The proposed Technical Specification changes for North Anna Unit 2 are provided in Attachment 2.

A Safety Analysis for the proposed changes is included in Attachment 3.

VEP-NOS-8, "A Study of the Effects of a Reduced Number of Thimbles of the Results of INCORE Flux Map Analysis," is provided es Attachment 4.

Virginia Power satisfactorily maintains the movable incore detector system at the North Anna Power Station. The incore detector tubes are routinely cleaned during refueling outages, as necessary, to ensure i

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the maximum possible_ number of operable thimbles.

Incore detectors which are determined to be inoperable are replaced during scheduled. maintenance If' multiple failures occur and the supply of new detectors is outages.

not adequate, detectors will be replaced to permit access to the maximum number -of-thimbles for. flux map analysis. ' Limit switch corrections are made whenever large mesh corrections are noted in the final INCORE i

computer code-results.

'- This maintenance should ensure that the maximum number of thimbles are available for obtaining flux map data.

However, extraordinary i

' circumstances. could prevail which do not allow for the normal monthly surv'e111ance of hot channel factors, and the unit would have.to shut down.

j due to a surveillance requirement rather than actual hot channel factor

-violations.

In order to avoid a forced reactor outage due to a reduced number of accessible flux map thimbles, the monthly surveillance requirements.could be me t-with the proposed Technical Specification changes.-

VEP-NOS-8 (Attachment -4) clearly demonstrates that all hot channel factors can be accurately monitored--with a reduced number of thimbles flux map if_the proposed additional uncertainties are added to the measured hot channel factor values. Finally, the reduced number of thimbles. flux map will reduce the station man-rem exposure by reducing the number of at-power containment entries to_ repair the movable incore detector system.

This_' request. has been reviewed and approved by the Station Nuclear Safety and Operating Committee and -the Safety Evaluation and. Control Staff.

It- 'has' been determined that.this request does not involve an unreviewed: safety question as defined in 10 CFR 50.59.

This change does not pose a-significant hazards consideration as defined in 'the Federal. Register, 48FR14870.

The basis for this determinationLis'provided'in example (vi) 'which partially-states,_

"A change ;which either may result in sameLincrease to the probability or consequences of a previously analyzed accident or may reduce in some way a safety. margic,.but.where the results of the change are clearly within-all' acceptance criteria with respect.to the system'or component-specified in the ; Standard Review Plan".

The proposed changes reduce the-minimum

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number of thimbles-required for monthly,' surveillance of - hot - chancel factors.(only -if --38 ' thimbles 'can. not be physically monitored), but additional conservatisms will be applied to ;the measured hot channel' factors obtained. with - a : reduced number of: thimbles -flux map :to ensure that all hot' channel factors are within-their Technical Specification l-

. limits.;

Thef proposed changes have been reviewed with respect to the l

accident ~ analyses _ in --the North Anna.UFSAR and Enone are 'affected,-

L therefore these' changes:do not pose a-significant hazards consideration.-

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Letter to:

Mr. Harold R. Denton

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We have reviewed this request in accordance with the criteria in 10 CFR-170.12. A voucher check in the amount of $150 is enclosed as an application fee.

Very truly yours, W. L. Stewart Attachments 1.

Proposed Technical Specification Changes Unit 1 2.

Proposed Technical Specification Changes Unit 2 3.

Safety Evaluation 4.

VEP-NOS-8, "A

Study of the Effects Reduced Number of Thimbles on the Results of INCORE Flux hap Analysis", October, 1983.

5.

Voucher Check for $150 cc:

Dr. J. Nelson Grace Regional Administrator Region II.

Mr. M. W. Branch NRC Resident Inspector North Anna Power Station Mr. Charles Price Department of Health

-109 Governor Street Richmond, Virginia 23219 i

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The foregoing document was acknowledged before me, in and for the City and Commonwealth aforesaid, today by W.

L.

Stewart who is Vice President Nuclear Operations, of the Virginia Electric and Power Courany.

He is duly authorized to execute and file the foregoing document in behalf of that Company, and the statements in the document are true to the best of his knowledge and belief.

Acknowledged before me this \\ A day of bd 19 D My Commission expires: Y A. m.....

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