ML20069E050

Responds to IE Bulletin 83-01, Failure of Reactor Trip Breakers (Westinghouse DB-50) to Open on Automatic Trip Signal. Operators Instructed to Rept Reactor Trip Breaker Failure as Significant Event as of 830301

ML20069E050
Person / Time
Site:	Robinson
Issue date:	03/04/1983
From:	Hurford W CAROLINA POWER & LIGHT CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
REF-SSINS-6820 IEB-83-01, IEB-83-1, LAP-83-58, NUDOCS 8303210367
Download: ML20069E050 (3)

Text

.,

!g e

W 4.,' +

e

.: 9'90qRu ,E ZN 5[W " '~

Carolina Power & Light Company

. W 041983 A10 . I E d3 g q i ERIAL:'

LAP-83-58 Mr. ' James P. O'Reilly, Regional Administrator United States Nuclear Regulatory Commission Region II 101 Marietta Street,. N.W. , Suite 3100 Atlanta, GA 30303 H. B. ROBINSON STEAM ELECTRIC PLANT, UNIT NO. 2 DOCKET NO. 50-261 LICENSE NO. DPR-23 RE3PONSE TO IE BULLETIN NO. 83-01

Dear Mr. O'Reilly:

Carolina Power & Light Company (CP&L) has reviewed your letter, dated February 25, 1983, IE Bulletin 83-01, " Failure of Reactor Trip Breakers (Westinghouse DB-50) to Open on Automatic Trip Signal." In response to this Bulletin, CP&L hereby provides the following information relative to the H. B.

Robinson Steam Electric Plant, Unit No. 2 (HBR2). Carolina Power & Light Company has performed all of the actions required by this Bulletin and wishes to state that due to two previous failures of Reactor Trip Breakers at HBR2, significant corrective action had already been implemented prior to the Salem event. ' These additional actions are described in the appropriate sections of this response.

Bulletin Item 4.a Action Item I required surveillance testing of the undervoltage trip function on the Reactor Trip Breakers independent of the shunt trip within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of receipt of the Bulletin. 'Ihis testing was performed by Periodic Test (PT) 19.0 (P,eactor Protection Logic Test) on February 26, 1983 with satisfactory results. It should be noted that a monthly PT for testing of these breakers has been in place at HBR2 since initial plant start-up.

Bulletin Item 4.b Action Item 2 required a review of the Reactor Trip Breaker Maintenance Program for conformance to the vendor recommendations. Cleaning and lubrication of these breakers has been performed annually since November, 1974 following receipt of Westinghouse Data Letter 74-2. This cleaning and inspection was formally implemented by a sign-off step on Periodic Test 19.0 in January, 1975. A specific preventative maintenance instruction is under r303210367 830304 .

{DRADOCK 05000261PDR 411 Fayetteville Street

• P. O. Box 1551

• Raleigh, N. C. 27602 e

i. .

~

~ ~

g.e

V -

m. ;j.,

. s '

, J

% :aJt; " ~

' ' '~~

is.' s r .

- 1 d _ i

. tJ.aP. 0'Reilly; .

~ y ,

4

..developmentias a result of a previous failure- (see 'below) and will' be

<. available for the next: scheduled preventative maintenance. This procedure (will! provide in a single document all the information necessary to ensure j.conformance with the vendor recommendations.

H. B. Robinson, Unit. No. 2 has, 'since 1974, had two occurrences of a

, Reactor Trip. Breaker failing to trip. , Both of these occurred during periodic

- testing. iThe first f ailure occurred on September 23, 1981.and was reported in an Information Report (Serial: .RSEP/81-1783). dated November 10, 1981. The cause of f ailure ~was determinad to be a loss of spring tension in the

[~ lundervoltage: (UV) device and resultant binding which was attributed to -normal wear.- . The- UV ' device was replaced. The second f ailure occurred on l December' 20, 1982 and was. reported in Information Report (Serial: RSEP/83-62)

' dated January- 19, 1983. .The cause of ~ this f ailure was preliminarily-

' identified and reported as inadequate lubrication; however, additional investigation has also identified that an abnormally dusty environment caused by outage activities probably contributed significantly to the failure.- In

. addition to this investigation, three of the UV devices were replaced with existing stock and the fourth will be replaced when ordered parts arrive on isite. An Engineering Evaluation of these events which addresses the lubricant

' type - and the advisability .of periodically replacing the Undervoltage Trip Device is in progress.

Considering the root causes of these f ailures and the good operational history since 1974 (approximately 800 required breaker operations c and test operations with only two f ailures gives a failure rate of .25%), an annual PM frequency is believed to be appropriate and additional maintenance

- to comply with the requirements of Action Item 2 is not considered necessary.

In addition to the testing described in this Bulletin, H. B.

Robinson' personnel- bench tested three of the shunt trip devices in December, 1982. Shunt trip testing will continue on an annual basis and will provide additional assurance of 'the continued operability of the Reactor Trip L Breakers. As part of our overall investigation into these failures, we are also reassessing the Q-list status of these breakers and their components with the' vendor. -

Bulletin Item 4.c Action Item three required that all licensed operators be informed of the failure-to-trip event at the Salem Plant and to review the appropriate emergency operating procedures. This training, which consisted of a presentation on the Salem event by the Shift Technical Advisors, and a review of Emergency Instruction 14 (Reactor Trip), was initiated with the on-coming midnight shift personnel on Febtuary- 25, 1983 and has continued for each

- operating shif t prior to their resumption of shif t duties. All operating personnel have been trained with the exception of four (4) personnel who are l

away f rom the site for training. These operators will receive the above training upon their return to the plant site and prior to their return to an

operating ~ shif t.

l

. . ____m..._ __s.-., _ . , . . . _ _ _ . ~_ . _ . _ - __, . _ _ _ _ . . . - . . - _ _ _

f..

, F ,f o :

J. P.~-O'Reilly I

H.' ' Bulletin item 4.d The H. B. Robinson Technical Specifications do not contain an LCO for the Reactor Trip Breakers and therefore, the failure of the breakers is

- not, in our opinion, reportable pursuant to 10CFR50.72. However, in an effort to provide the requested information to the NRC, .the HBR2 operators have been instructed to report a Reactor Trip Breaker f ailure as a Significant Event as of-March 1, 1983.

We believe that the above information addresses the requirements of the Bulletin and in fact goes beyond the Bulletin requirements in several areas. Should'you have any questions, please contact me or a member of my staff.

Yours very truly, W. J. Hurf d Manager Technical Services AWS/HTC/kjr (6350NLU)

Sworn to and subscribed before me this 4th day of March,1983 s' & m/

Notary (Seal) II8triri, My commission expires: October 4, 1986 N4 cc: Mr. G. Requa (NRC) - / .

5 Mr. Steve Weise (NRC-HBR) { !g0TARyi j 5i#UBLIC I!

%  %.  ?

5 f g

-y -