ML20056H363

TS Change Request NPF-38-140 to License NPF-38,modifying TS 3.3.3.2 by Reducing Specified Min Number of Incore Detector Locations from 75% to 50% for Remaining Portion of Current Fuel Cycle 6

ML20056H363
Person / Time
Site:	Waterford
Issue date:	09/07/1993
From:	Barkhurst R ENTERGY OPERATIONS, INC.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20056H364	List: ML20056H363 ML20056H371
References
W3F1-93-0090, W3F1-93-90, NUDOCS 9309090198
Download: ML20056H363 (8)

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==~ ENTERGY no aa KMro LA 70066-0751 Tet 504 739 6661 Ross P. Barkhurst vwm-amm  ;

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September 7,1993  :

i Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555

Subject:

Waterford 3 SES Decket No. 50-382 License No. NPF-38  !

Technical Specification Change Request NPF-38-140 l t

Gentlemen:

( The attached description and safety analysis support a change to the  ;

l Waterford 3 Technical Specifications (TS). '

This proposed change concerns the incore detector Limiting Condition for-Operation (LCO) 3.3.3.2.and proposes an interim change applicable for the >

remainder of Fuel Cycle 6. This change modifies the operability i requirements for the Incore Detection System by reducing the minimum number of required incore detector locations from the current specified 75% to a proposed 50%. j The proposed change has been evaluated in accordance with 10CFR50.91(a)(1) using criteria in 10CFR50.92(c)'and it has been determined that the proposed change involves no significant hazards considerations. ,

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090000 9309090198 930907382 DR ADDCK O ,,; .l

Technical Specification Change Request NPF-38-140 W3F1-93-0090 Page 2 September 7,1993 The circumstances surrounding this change do not meet the NR'J's criteria for exigent or emergency review. However, as described herein these l circumstances may change at any time; therefore, an expeditious review is 3 respectfully requested.

Should you have any questions or comments concerning this request, please l contact Paul Caropino at (504)739-6692. j l

Very truly yours, i i

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SS MJJ R.P. Barkhurst j Vice President, Operations l Waterford 3 l l

RPB/PLC/dc 1

Attachment:

Affidavit NPF-38-140 1

cc: J.L. Milhoan, NRC Region IV D.L. Wigginton, NRC-NRR R.B. McGehee N.S. Reynolds NRC Resident Inspectors Office Administrator Radiation Protection Division (State of Louisiana)

American Nuclear Insurers

UNITED STATES OF AMERICA l HUCLEAR REGULATORY COMMISSION In'the matter of )

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Entergy Operations, Incorporated ) Docket No. 50-382  ;

Waterford 3 Steam Electric Station )  !

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1 AFFIDAVIT R.P. Barkhurst, being duly sworn, hereby deposes and says'that he is Vice.  !

President Operations - Waterford 3 of Entergy Operations, Incorporated; that he is duly authorized to sign and file with the Nuclear Regulatory Commission i the attached Technical Specification Change Request NPF-38-140; that he is i familiar with the content thereof; and that the matters set forth therein are  !

true and correct to the best of his knowledge, information and belief.  !

C3 i R.P. Barkhurst l Vice President Operations - Waterford 3 STATE OF LOUISIANA )

) ss  :

PARISH OF ST. CHARLES ) l Subscribed and sworn to before me, a Notary Public in and for the Parish and  ;

State above named this 7 " day of S EPT6BZ2_ ,1993.  !

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1W Cu Notary Public.

My Commission expires Ov irla L t e r, .

DESCRIPTION AND SAFETY ANALYSIS OF PROPOSED CHANGE NPF-38-140 This proposed change modifies Technical Specification (TS) 3.3.3.2.a by reducing the specified miidmum number of incore detector locations from 75% to 50% for the remaining pertion of the current fuel cycle.

Existino Specification See Attachment A Erroosed Specification See Attachment B Descriotion The proposed change to the Waterford 3 TS modifies the incore detection system operability requirements to allow power distribution monitoring and calibration functions to be performed with as few as 50% of incore detector locations operable. Specifically a footnote has been added to TS 3.3.3.2.a that states "For the remainder of fuel cycle 6 the incore detection system may be considered OPERABLE with < 75% and 2 50% of all incore locations provided the appropriate penalties are applied to the COLSS and CPCs."

To compensate for any increased uncertainty when the number of operable detector locations falls below the existing specification of 75%, revised addressable constant values will be installed in the Core Operating Limit Supervisory System (COLSS) and Core Protection Calculator System (CPCs). In addition Waterford 3 will evaluate the core power distribution once every 15 days, which is twice as often as the TS now require.

A similar license amendment request has been reviewed by the staff as indicated in Federal Register Vol. 58, No. 51 page 14594 dated March 18, 1993, Baltimore Gas & Electric Co.

The purpose of incore detection instrumentation is to provide inputs for determination of core power distributions, perform validation of the CPC power distribution, and provide inputs to the COLSS. The Waterford 3 fixed incore detection system consists of 56 incore detector locations within selected fuel

assemblies of the reactor core. Each location contains a string of five self-powered, Rhodium neutron detectors positioned axially at elevations corresponding to 10, 30, 50, 70, and 90% of core height.

Currently, four detector locations (which accounts for 20 detectors) are not functional due to the instrumentation thimble being cut off (2) or the instrument being broken off inside the thimble (2). At this point in Fuel Cycle 6, an additional 30 detector failures have occurred. These 30 detector failures combined with the 20 non-functional detectors, have caused 12 of the detector locations to be inoperable. At present, 78.6% of the detector locations are operable. However, there are two locations where a single detector failure will render the location inoperable and should these failures occur 75% of the locations will be operable.

The TS requires four of the five detectors in a string to be operablr. for the location to be operable and that 75% of all detector locations be opeable.

Additionally, "a minimum of two quadrant symmetric incore detector locations per core quadrant" are required.

Recognizing that additional detector failures could impose upon the 75%

Operable location criteria, Waterford 3 is seeking temporary relief for the remainder of Fuel Cycle 6. Detector assemblies were last replaced during Refuel 4, and 42 assemblies are scheduled for replacement daring Refuel ri, scheduled to begin in March 1994. Currently there are 4 operable quadrant symmetric detector locations per core quadrant. Since the TS only requires two there is no immediate concern over this requirements.

The incore detector signals are used by the off-line computer code CECOR to calculate the spatial power distribution in the core including the tilt and power peaking factors. The incore detector signals are used by the COLSS monitoring program to assist the operator in maintaining DNBR, L';near Heat Rate, Azimuthal Tilt, and Axial Shape Index, within their specified operating limits during normal operation.

If the incore detection system becomes inoperable, the Excore Detector System must be :.md for monitoring core power distribution. Because the Excore Detector System is more restrictive, maximum core power must be limited to approximately 90% of full power to comply with TS requirements.

Entergy Operations Inc. performed a new analysis of the overall CECOR power peaking factor measurement uncertainties to determine the effects of monitoring the power distribution with as few as 50% of the locations operable and thereby avoid the power constraint associated with using the excore system. This analysis models the present instrument failures previously

mentioned and combines them with various additional postulated failures so as i to model up to 50% of the detector locations as failed. In this analysis a failed location is modeled as having all five detectors failed. Additional randomly chosen detector failures were also modeled within the bounds of the quadrant symmetric detector location requirements of the TS. From this analysis, the resultant overall uncertainty on CECOR measured planar radial 4 peaking factors (Fxy) increases by less than 1% compared to the value of 6.92% l given in the NRC approved CECOR Topical Report MSS-NA3-P, " Verification of )

CECOR Coefficient Methodology for Application Pressurized Water Reactors of l the Middle South Utilities System," August 1, 1984. Additionally, the ABB-Combustion Engineering Huclear Fuel organization has assessed the impact of the increased CECOR Fxy measurement uncertainty upon the calculations performed by the COLSS and CPCs. The impact will be accounted for in revised values of addressable constants input to these systems. For conservatism, a full 1% increase in the CECOR Fxy measurement uncertainty was utilized for the generation of the new constants. The increased accounting for the measurement-calculational uncertainties will provide assurance that actual core peaking factors are conservatively bounded by the measured peaking factors. Therefore, operating the reactor within the appropriate TS LC0 will  ;

continue to assure that actual core power distributions remain within the design parameters assumed for applicable event analysis contained in the Updated Final Safety Analysis Report (UFSAR).

Safety Analysis The proposed change described above shall be deemed to involve a significant hazards consideration if there is a positive finding in any of the following areas:

1. Will operation of the facility in accordance with this proposed change involve a significant increase in the probability or consequences of an accident previously evaluated?

Response: No l

The proposed change would relax requirements for the number of operable ;

incore detector locations. The function of the incore detectors is to j verify that the core power distribution is consistent with the l assumptions used in the safety analysis. Sufficient measurements will l be required to adequately verify compliance with power distribution 1 Technical Specification limits. Penalties will be applied to the COLSS and CPCs to account for the increased uncertainties of values measured l by the incore detectors prior to using incore detectors to monitor Technical Specification Limits when the number of operable detector l

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I locations falls below the current requirement. This will ensure that all current Technical Specification and fuel design limits are protected and the core power distribution assumptions in UFSAR analysis remain valid. Therefore, the proposed change will not involve a significant increase in the probability or consequences of any accident previously evaluated.

2. Will operation of the facility in accordance with this proposed change create the possibility of a new or different type of accident from any accident previously evaluated?

Response: No.

The proposed change will not alter the operation of the plant or the manner in which it is operated. Reducing the minimum number of operable incore detector locations will not introduce any new failure modes. Therefore, the proposed change will not create the possibility of a new or different kind of accident from any accident previously evaluated.

3. Will operation of the facility in accordance with this proposed change involve a significant reduction in a margin of safety?

Response: No The proposed change will continue to protect the current Technical  !

Specification power distribution limits. Use of increased measurement  !

uncertainty factors are required commensurate with the reduction in the l minimum number of incore detector locations. The increased measurement uncertainty factors assure that power distribution calculations based on the incore system will continue to be conservative and that the existing LCOs specified for Axial Shape Index, Azimuthal Power Tilt, Radial Peaking Factors, Local Power Density, and DNBR will not be exceeded.

Therefore, the proposed change will not involve a significant reduction in a margin of safety.

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Safety and Sianificant Hazards Determination l

" Based on the above safety analysis, it is concluded that: (1) the proposed j change does not constitute a significant hazards consideration as defined by 10 CFR50.92; and (2) tnere is a reasonable assurance that the health and safety of the public will not be endangered by the proposed change; and (3) this action will not result in a condition which significantly alters the impact of the station on the environment as described in the NRC final environmental statement."

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