ML20202E518

Responds to NRC Ltr Re Violations Noted in Insp Rept 50-382/97-24.Corrective Actions:Engineering Calculation EC-M95-012 Has Been Revised to Remove All CSP & Rwsp Vortex Calculations

ML20202E518
Person / Time
Site:	Waterford
Issue date:	02/11/1998
From:	Ewing E ENTERGY OPERATIONS, INC.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
50-382-97-24, W3F1-98-0018, W3F1-98-18, NUDOCS 9802180169
Download: ML20202E518 (4)

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W3F198-0018 A4.05 PR February 11,1998 i U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555 SubJc a. Waterford 3 SES Docket No. 50-382 License No. NPF-38 NRC Inspection _ Report 97-24 Reply to Notice of Violation Gentlemen:

In accordance with 10CFR2.201, Entergy Operations, Inc. hereby submits in Attachment 1 the response to the violation identified in Enclosure 1 of the subject inspection Report.

if you have any questions concerning this response, i :ase contact me at (504) 739-6242 or Tim Gaudet at (504) 739 6666.

Very truly yours,

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E.C. Ewing ggD\',,

Director, Nuclear Safety & Regulatory Affairs ECE/DMU/ssf -

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cc: E.W. Merschoff (NRC Region IV), C.P. Patel (NRC-NRR),

J. Smith, N.S. Reynolds, NRC Resident inspectors Office 9903190169 211 P PDR ADOCK 0 382  !

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Attachment is W3F198 0018 Page 1 of 3 ATTACHMENT 1 ENTERGY OPERATIONS, INC. RESPONSE TO THE VIOL ATION IDENTIFIED IN ENCLOSURE 1 OF INSPECTION REPOR 97 24 VIO_LATION NO. 9724-05 10 CFR Part 50, Appendix B, Criterion Ill, " Design Control," states, in part, that measures shall be established to assure that the design basis, as defined in Section 50.2 and as identified in the license applicailon, for those structures, systems, and components to which this appendix applies are correctly translated into specifications.

Contrar/ to the above, in December 1996, the licensee failed to properly translate design basis requirements into specifications, in that, the correct level for the onset of vortexing, which could affect net positive suction head for the safety injection and spray pumps, was not properly determined. Specifically, Calculation EC-M95-012. " Minimum Pipe Submergence to Prevent Vortexing," identified the minimurn level in several safety-related tanks, including the refueling water storage pool, required to prevent vortexing; however, the calculation did not include consideration of pump recirculation flow back to the tank.

This is a Severity Level IV violation (Supplement 1) (50-382/9724-05).

RESPONSE

(1) Reason for the Violation The root cause of this violation is human error in that all design inputs were not considered for a calculation. An inadequate review during preparation of calculation EC M95-012 failed to identify and account for the affect of minimum recirculation flow to the refueling water storage pool (RWSP) and condensate storage pool (CSP) when determining the minimum pool height to prevent vortexing.

Revision 1 to Calculation EC-M95-012 was approved on December 4,1996.

The purpose of this calculation was to determine the minimum liquid level in the CSP, boric acid makoup (BAM) tanks, emergency diesel generator (EDG) storage & feed tanks, RWSP and volume control tank (VCT) to prevent air entrainment, as a result of vortexing during opera. ion of the associated pumps, As documented in CR-97-1596, it was determined that calculation EC-M95-012 did not account for the affect of minimum recirculation to the CSP ar,d RWSP when calculating the minimum pool height to prevent vortexing.

, Att: chm:nt to W3F1-98-0018 P g] 2 of 3 Recirculation flow will cause addFional perturbations in the storage pools, which will increase the level at which vortexing would occur. Therefore, because the effects of minimum racirculation flow were not considered, the calculated minimum water level to prevent vortexing in the RWSP and CSP was non-conservative.

(2) Corrective Steps That Have Been Taken and the Results Achieved

. Engineering calculation EC-M95-012 has been revised to remove all CSP and RWSP vortex calculations.

. Scaled models, which included the minimum recirculation flow, were built for the CSP and RWSP. Based on scaled testing, a vortex breaker design was established. Vortex breakers were subsequently installed in the CSP and RWSP.

. Engineering calculations EC-M97-025 and EC-M97-026 for the CSP and RWSP respectively, have been prepared and approved to address

vortexing in these storage pools. The affects of minimum recirculation flow have been considered in the calculations.

(3) Corrective Steps Which Will Be Taken to Avoid Further Violations e in addition to the CSP and RWSP, calculation EC-M95-012 also considered vortexing for the following tanks: the vo!ume control tank (VCT), boric acid management (BAM) tanks, emergency diesel generator (EDG) feed tenks and EDG storage tanks. A detailed review is in progress to determine the vortex critical height for these tanks. This review w!:1 be completed by April 50,1998. An operability review for the above tanks was performed as part of CR-97-1844 on July 14,1997. This review concluded that the useble volume and/or function of the tanks was not adversely affected by vortexing.

. In accordance with NOECP-011, " Engineering Calculation?" multiple barriers are in place to identify the design inputs that are to be used in calculations. These include procedural guidance for the preparation and review of calculatioi4 design verification, review of supplier performed calculations, supervisor approval and, in some cases Design Review Committee (DRC) and Plant Operatinc Review Committee (PORC) review.

Waterford 3 believes this guidance is sufficient to ensure calculations are i adequately prepared, reviewed and approved.

The onset of vortex formation in tanks is unpredictable. Several correlations have been established for determining vortex formation, but are based on empirical data rather than analytical methods. Due to the specific expertise required to perform the vortex analysis, W3 subcontracted the analysis to an independent consultant. The original

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4- - correlation used by the contractor failed to account for the effects of -

recirculation riow Scaled model testing of the RWSP and CSP was then

- performed during RF8 using various vodex breaker designs. The onset of.

vorisxing in the CSP and RWP was then determined from the results of the scale model test.-

Given the unique method required to determine the vortex height in the

- CSP and RWSP, failure to initially consider the effects of recirculation flow on vortex height allowance is considered an isolated event.-- No additional i corrective action to address this event is required.-

(4) . Date When Full Compliance Will Be Achieved The above corrective action that is in progress will be completed by April 30,1998. Upon completion of that item, Waterford 3 will be in full compliance.

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