ML17261B069

Discusses Testing Frequency for Insp of Incore Neutron Monitoring Sys Thimble Tubes,Per NRC Bulletin 88-009.Thimble Tube Indicating Greatest Wear Recently Repositioned in Effort to Minimize Future Wear

ML17261B069
Person / Time
Site:	Ginna
Issue date:	06/01/1990
From:	Mecredy R ROCHESTER GAS & ELECTRIC CORP.
To:	Andrea Johnson NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM), Office of Nuclear Reactor Regulation
References
IEB-88-009, IEB-88-9, NUDOCS 9006080186
Download: ML17261B069 (3)

Text

ACCELERATED DTRIBUTION DEMONS~TION SYSTEM REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:9006080186 'OC.DATE: 90/06/01 NOTARIZED: YES DOCKET Ã"

FACIL:50-244 Robert Emmet Ginna Nuclear Plant, Unit 1, Rochester G 05000244 AUTH. NAME AUTHOR AFFILIATION MECREDY,R.C. Rochester Gas & Electric Corp.

RECIP.NAME RECIPIENT AFFILIATION JOHNSON,A.R. Project Directorate I-3

SUBJECT:

Discusses testing frequency for insp of incore neutron monitoring sys thimble tubes,oer Bulletin 88-009.

DISTRIBUTION CODE: IEISD COPIES RECEIVED:LTR ENCL 0 SIZE:

TITLE: Bulletin 88-09 Thimble Tube Thinning Jzn Westinghouse Reactors NOTES:License Exp date in accordance with 10CFR2,2.109(9/19/72). 05000244 RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR E CL ID CODE/NAME LTTR ENCL PD1-3 LA PD1-3 PD JOHNSON,A INTERNAL: AEOD/DOA AEOD/DSP NRR BUCKLEY,B NRR HOU,S NRR RAMSEY,J G 02 RGN1 FILE 01 EXTERNAL: LPDR NRC PDR NSIC

~VV VS7S~~

NOTE TO ALL "RIDS" RECIPIENTS:

PLEASE HELP US TO REDUCE WASTE! CONTACT THE DOCUMENT CONTROL DESK, ROOM P 1-37 (EXT. 20079) TO ELIMINATEYOUR NAME FROM DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEED!

TOTAL NUMBER OF COPIES REQUIRED: LTTR 13 ENCL

ROCHESTER GAS AND ELECTRIC CORPORATION i 89 EAST AVENuE. ROCHESTER, 'N,Y. 14649.0001 C% %"

June 1, 1990 U.S. Nuclear Regulatory Commission Document Control Desk Attn: Allen R. Johnson Project Directorate I-3 Washington, D.C. 20555

Subject:

NRC Bulletin No. 88-09: Thimble Tube Thinning in Westinghouse Reactors R.E. Ginna Nuclear Power Plant Docket No. 50-244

Dear Mr. Johnson,

Per our letter of June 6, 1989, Rochester Gas and Electric Corporation agreed to provide an appropriate testing frequency for inspection of incore neutron monitoring system thimble tubes as required by NRC Bulletin 88-09. RG6E has conducted three tests of the subject thimble tubes (February 1988, May 1989, and April 1990) using an Eddy Current testing procedure and an acceptance criterion of 65% through-wall wear as described in the June 6 letter. All thimble tubes have been inspected and meet this criteria with the greatest positive increase in through-wall wear measured to be 10%

between any two consecutive years (i.e., 1988 and 1989, and 1989 and 1990) and on different thimble tubes. Only one thimble tube currently indicates through-wall wear greater than 50% with the next greatest wear measured to be less than 25%. The thimble tube indicating the greatest wear was recently repositioned in an effort to minimize its future wear.

As a result of these three tests, RGGE has determined that a testing frequency of once every other refueling outage (i.e., once every two years) is appropriate for thimble tube inspections when the previous inspection indicates less than 45% through-wall in the wear area. Thimble tubes with greater than 45% through-wall, but less than 55% in the wear area will be inspected annually, unless through-wall wear has not changed between the previous two tests.

In this instance, the thimble tube will be inspected every other refueling outage.. Appropriate corrective action will be performed if a thimble tube exceeds 55% through-wall in the wear area.

The above testing frequencies were determined as 'follows. Applying the maximum wear rate of 10% to a single thimble tube initially measuring less than 45% through-wall wear would not result in the acceptance criterion of 65% being exceeded over a two year period.

Applying this same wear rate, to a single thimble tube with through-wall wear ranging between 45% and 55% for one year will also not result in the acceptance criterion of 65% being exceeded. The 65%

acceptance criteria includes necessary instrumentation uncertainty considerations. Pmgz

'<QQI~QPQ f el+ '??QQ&Qi F'DR ADOCK Q 'QQQ24+

F'DC

'~

i(p ywon.~~~~

Q

These testing frequencies may be changed if the maximum wear rate between tests indicate either excessive or significantly less through-wall wear. The NRC will be notified upon any change in testing frequency.

Robert C. Mecre Division Manager Nuclear Production Subscribed and sworn to before me on this 1st day of June, 1990 SAMUEL H. BAOWNE NTARY PUBLlC, Stats ol Now Yet ration No. 49>7041 Qtts inMonoe Cy. I Wayne My Constsssan spies Deo.28, 19 Notary Public MDFN120 xc: Allen R. Johnson (Mail Stop 14D1)

Project Directorate I-3 Washington, D.C. 20555 U.S. Nuclear Regulatory Commission Region I 475 Allendale Road King of Prussia, PA 19406 Ginna Senior Resident Inspector