ML19095A298

Submit Special Reports S1-77-01 Surry Unit 1 Hydraulic Shock Supports & S2-77-01 Missing Steam Generator Tube Plug - Hot Leg, Generator B, Row 1, Column 42.

ML19095A298
Person / Time
Site:	Surry
Issue date:	01/05/1978
From:	Stallings C Virginia Electric & Power Co (VEPCO)
To:	O'Reilly J NRC/RGN-II
References
Serial No. 001 LER 1977-001-00
Download: ML19095A298 (5)

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}~. James P. O'Reilly, Director S.?rial No~*.°QOl Office of Inapection and Enforcement FO&ci/DL3:daa*-,-- -*

u. s. Nw:leax Regulatory Commissicm Dock&t Noa. 50-280 Region II - Suite 818 50-281 230 Peachtree Stxeet, Northweat Licenae Nos. DPR-32 Atluta. Georgia 30303 . DPR-37

Dear Mr. O'Reilly:

The f ollawing Sptecial Reporta for Surry Units 1 and 2, respecti?ely t are .

enclosed for your. informad.on.

Special Report Sl-77-01, "Surry Unit 1 Rydraulic Shock Supports (Suubbers)"

Special. Report S2-77-0l, "Missiug Steam Generator Tube Plug - Bot Leg, Gen-erator :a, Row l, ColWllll 42 1'

• These reports have b** reviewed by the Station Nuclear Safety am Operating Committee a:ui will ba placed on the ageada for the next meeting of the System Nuclear Safety and Operating Committee.

Very txuly youra 9 C. M. Stallings Vica PresLieut - Power Supply and i'roduction Operations Eucloaurea (3 copiaa) cc:* Dr/' Em.at Volge.iau, Director 40 Copiea

• --*Office of InspectioD and 2nforcezunt Mr. .iill ;a, G. iicDonald., Directer 3 Copies Office of .Management Iufomation and Program Cont;rol

-780100044

SPECIAL REPORT Sl-77-01 SURRY UNIT 1 HYDRAULIC SHOCK SUPPORTS (SNUBBERS}

The first functional testing of hydraulic shock suppressors required by Technical Specification 4.17.D was conducted on Surry Unit 2 in the September refueling outage. The extent of failures was reported in LER-77-12 (Docket No.

50-281). At that time, a committment was made to verify the condition of Unit 1 snubbers.

Activity was initiated* on those snubbers outside of containment and con-centrated on those snubbers which *have not yet been converted to ethylene pro-phlene seals. Prior to commencement of the Unit 1 Steam Generator Evaluation outage in mid-November, thirty-four snubbers were replaced with new or rebuilt snubbers that met functional testing criteria.

During the outage, snubbers were initially screened into three categories (1) those requiring seal replacement and/or those which appeared marginal and that indicated a high probability of failure might occur in testing; (2) those which upon removal and visual examination appeared satisfactory, and (3) those not requiring functional testing only a visual inspection. Seventy-eight snubbers were screened into the first category, and were rebuilt or repaired as necessary.

All met functional testing acceptance critera. Of the snubbers in the second category, one met functional testing acceptance criteria and twenty-nine requir-ed only adjustment to meet functional testing acceptance critera. Thirty-six snubbers in the third category were visually inspected and appeared satisfactory.

Surry Unit 1 was started up on December 7, 1977, with all snubbers operable.

'..._ *,.~.:

SR-S2-77-01 MISSING STEAM GENERATOR TUBE PLUG-HOT LEG, GENERATOR B, ROW 1, COLUMN 42.

SURRY POWER STATION UNIT 2 DOCKET NO. 50-281 LICENSE NO. DPR-37 SEPT. 1977 VIRGINIA ELECTRIC AND POWER COMPANY

INTRODUCTION During the Surry Unit 2 Outage of July 11, 1977*an explosive plug was discovered to be missing from Ro~ 1 Column 42 in the hot leg of Steam Generator B. It is the intent of this report to discuss the plug lost and possible stopping places.

DISCUSSION Th~ location, Row l Column 42, in the inlet (TH) side 'of 2B Steam Generator was plugged on October 20, 1976 as a preventive measure. Plugging was verified by second visual check. On July 11, 1977, a visual inspection determined that no plug was inserted at Row 1 Column 42. Two possibilities present themselves to explain the .fate of this plug.

First, in March, 1977 a plug was found in the channel head of Unit 2 Steam Generator B, inlet. By the identification number, Westinghouse concluded that the plug came from one of six.tubes (R36/C76, R42/C61, R42/C63, R43/C60,.

C43/C62, R43/C63) and recommended that all six of those tubes be checked for plugs. However, Vepco Non-Destructive Testing and Quality Assurance efforts verified that the six tubes in question were in fact still plugged *

. Westinghouse had further stated that a visual examination of the plug showed it had been only partially expanded and a total detonation was not achieved upon installation *. Since Rl/C42 was not a leaking tube, it is not unlikely that a plug missing from that location would not be noticed during a subsequent hydrostatic test. It is possible that the plug found in the channel head in March, 1977 came from. Row 1, Column 42.

Second, during the same inspection that found the Rl/C42 plug missing, a plug was found loosely inserted into R29/Cll, a location not in the plugging program and not intended to be plugged. The R29/Cll plug was sent to the Westinghouse Nuclear Service Division Waltz Mill Facility for examination. A

DISCUSSION (CONTINUED)

, 2 -

dimensional check was performed showing no change from fabrication dimension indicating that the plug had not been "fired". Microscopic examination of the plug by Westinghouse determined that the plug came from heat number NX7853, but the identification number was not legible and positive identifi-cation of when or where the plug was installed was impossible. It is possi-ble that the R29/Cll plug was inserted into that location by mistake and was never exploded. However, the supposition can be made that the Rl/C42 plug may have dropped out and reinserted itself, under flow conditions, into the R29/Cll position.

On the possibility that back flow may have carried the plug into the reactor at some time when RCP "B" was idle, a thorough examination of the reactor vessel above and below the core was carried out by CCTV. No loose material was found by this inspectiono CONCLUSIONS Two explanations concerning the missing Rl/C42 plug have been presented, the first being more credible, but more importan_tly it must be concluded that no plugs are loose in the loop or unaccounted for._ Tubes Rl/C42, R29/Cll and those tubes around R29/Cll were all plugged on July 21, 1977. With the recent achievement of a new, more reliable method cf photographic verification of plugging maps, speculative explanations of missing plugs should not be necessary.