ML20064B739

From kanterella
Jump to navigation Jump to search
/01T-0 on 780916:3 MSIVs(NS03A,NS04A,NS04B) Had Leakage Rates in Excess of Maximum Allowable Due to Stem Packing,Cracked Stellite Weld & Failure of Main Poppet to Seat Properly.Msiv Failures Being Investigated
ML20064B739
Person / Time
Site: Oyster Creek
Issue date: 09/29/1978
From: Ross D
JERSEY CENTRAL POWER & LIGHT CO.
To:
Shared Package
ML20064B738 List:
References
LER-78-018-01T, LER-78-18-1T, NUDOCS 7810100075
Download: ML20064B739 (4)


Text

.. . r o n... m .. . . . . ..... . . . .. .. . . . . .

47 77) y? . LICENSEE EVENT REPORT

' CONTROL BLOCx: l l l l l l l (PLEAsE FRINT oR TYTE ALL REQulRED INFonMATioNi 1 6 2, l o t i8 l9l N JUCENSEE

' J ) 0 lCODE C l P l141 lgl5010 l - l 0 L4l CENSE 1

0 l 0NUM8E9 l 0 l 0 l- l 0 l 0 25l@l264 l 1L6lCENSE 1 l 1TYPE l 1JCl@l57 CATl

$8

[@

con'T lolil 3{C"[,c l L l@l61 015 l DOCKET 0 l 0 NUM8ER l 0 l 2 i ! 19 l@l 019 l 1 l 6 l 7 l 8 }@l01912191718 l@

7 8 60 68 69 EVENT Q ATE 74 75 REPORT DATE 80 i

EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h l lo12l l As a resul t of leakage rate measurement tests performed on MSIV's NS03A,  ;

~

,o,3,  ; NSO4A, and NSO4B during the days immediately following plant shutdown  ;

,o,,,; for refueling on September 16, 1978, all three valves were found to have  ;

, ,g,3, ,

leakage rates in excess of their maximum allowable as specified in (T.S.

4 Valve NS038 could not be tested because of excess leakage I o l e i L . 5. F.1.d) . ,

j3,7; i through valves NS03A an NSO4A.

s ria i 80 i

7 8 9 SYSTEM CAUSE CAUSE COMP. VALVE CCCE CODE SUSCCCE COMPONENT CODE SU8CCCE SU8 CODE

) @] 7 8 l Cl Dl@ l E l@' 12l M l@ l VlA lL lV lE lX [@ lF l@ l 0l@

9 10 11 13 18 19 20 SEQUENTIAL OCCURRENCE REPORT REVISION 5 gR mo E R EPORT NO. CODE TYPE NO.

2

@ y(g a l 7VENTl8 l YEl_[ AR lo il l8 l l/l l0 l1 l lTl l_l [ 0l

_ 21 22 23 24 26 27 28 29 30 31 32 K N AC CN CN PLANT ME HOURS 22 58 i FCR 8. SUP Li MANUFAC RER j! l33B lgl34Xl@ l Z lg 35 l36Z[@ l0 l0 l0 l0 l 37 40 y@

41 l42 Yl@ lN 43 l@ l44A 15 l8 l547l@

CAusE DESCRIPTION AND CORRECTIVE ACTIONS

! I i ) o l l The primary sources of leakage have been attributed to stem packing in (

,, ,,,; NSO48, stem packing and a cracked stellite weld in the body seat ring in g ggg NSO4A, and the failure of the main poppet to seat properly in NS03A. ,

,, ,3g l Necessary repairs will be performed during the ongoing outage. A compl-  ;

,, ,,; ete investigation of the MSIV failures is being conducted.  ;

8 9 80 STA  % POWER OTHER STATUS On v RY DISCOVERY CESCRIPTION l1 l 5 l l Hl@ l 0 l 0 l 0'2l@l" NA l l C l@l Leakage rate test l

'JTivirv Ca'ETE~T REtEiSEo cP aEtEASE AMouNr NA 0, ACriviTv @ l l LOCATION CF RELEASE @

NA l i l 68 l9l Z l @ l10Z l@l 7 11 44 45 l

80

  • ERSONNEL EXPCSURES NUP/ 9 E R TYPE DESCRIPTION NA l i l 71 1 01 o f 01@l Z l@l l

' ' ' 2

  • E R ScNN A',N;u'R, E S

.c ESCR ,TiO~@ l lt l . l l O f.,gERl 0 [@l: NA l

l 7 3 9 11 12 80 LCS$

CP OR CAMAGE TO FACILITY OES"RiPTtCN

, l i l 91 I }El@l NA l

r 4 1 '"

30 iSS DESCRIPTION *

!: l o l I N@l Weekly press release -- Oernber 3.1978

)

I I!llIIItittll1 P DA. A D B C K- #fV 117 5 /PFf 2-p e8 e, acq

' 7g1-/4(fghggggggg Donald A. h s P"CN E :

~

, -![ "C @ [ $ ,, ( r yM MadYs n Avenue unca8 Pcad Mornstown, New Jersey 07960 (201)455-8200 OYSTER CREEK NUCLEAR GENERATING STATION Forked River, New Jersey 08731 Licensee Event Report Reoortable Occurrence No. 50-219/78-18-1T Report Date September 29, 1978 Occurrence Date September 16, 1978 Identification of Occurrence Violation of the ' Technical Specifications, paragraph 4.5.F.1.d, when Main Steam isolation Valves NSO4A, NS03A, and NSO4B failed to meet their maximum allowable leakage rate. This event is considered to be a reportable occurrence as defined in the Technical Specifications, paragraph 6.9 2.a.3 Conditions Prior to Occurrence Start of a refueling shutdown.

Reactor mode switch: Refuel Moderator temperature: 166*F Reactor vessel head in place

\

Descriotion of Occurrence On September 16, 1978, at approximately 1600 hours0.0185 days <br />0.444 hours <br />0.00265 weeks <br />6.088e-4 months <br />, an unsuccessful attempt was made to pressurize the reactor vessel to perform a leakage rate measurement test on inboard main steam isolation valves NSO3A and NS03B. The maximum pressure reached was approximately four (4) psig. Subsequent investigations indicated that valve NSO3A was leaking excessively through the seat area and that valve NSO4A, which is in series with NS03A, had excessive leakage through the stem packing. Because of the stem packing leak, it could not be immediately determined if the seat sealing surface of NSO4A was also leaking.

On September 18, 1978, at approximately 1000 hours0.0116 days <br />0.278 hours <br />0.00165 weeks <br />3.805e-4 months <br />, to further explore the sealing capability of NSO4A, the main steam lines were flooded, with valves -

NSO3A and NSO4A closed. W a ter was observed flowing from a drain line down-l l

Jersey Central Power & Light Company is a Memcer of the Ger.eral Puche Ut; lit:es System

4

'Rsportable Occurrcnca No 50-219/78-18-IT

. Page 2 September 29, 1978 stream of both valves, thus confirming excessive seat leakage in addition to stem packing leakage. Main steam isolation valve NSO4B was tested in a conventional manner and was observed to have a leakage rate of approximately 14.5 SCFH. The maximum allowable is 11 9 SCFH. The stem packing was identified as the major source of leakage for this valve. It should be noted that valve NS03B could not be tested for leakage because of the excessive leakage through the 3A and 4A valves.

On September 20, 1978, another attempt was made to quantify the amount of leakage through valves NS03A and NSO4A. This was done by attempting to measure the air flow required to pressurize between the valves using a 0-100 SCFM rotometer connected to a 100 psig air source. The maximum air flow was measured to be 24 SCFM which corresponds to the maximum flow possible through the air supply hose and the associated piping connections.

Since a similar air supply system was used in the initial attempt to pressurize the vessel, it may be concluded, assuming that all of the leakage was through the MSIV's, that a differential pressure of 4 psig across the series valves corresponds to a flow rate of 24 SCFM through the valves.

Accarent Cause of Occurrence The stem packing was identified as the primary source of leakage for NSO4B and a contributing source of leakage for NSO4A. The cause of excessive seat leakage through NS03A and NSO4A has been preliminarily determined to be from two separate and distinct causes.

For inboard main steam isolation valve NS03A, the cause of the leakage has been attributed to failure of the main poppet-to seat properly. An inspection of the valve internals indicates excessive wear between the main poppet alignment pad and the lower guide on which it slides. This condition caused a shift in the main poppet path of travel causin'g the poppet not to seat properly.

For outboard main steam isolation valve NSO4A, the cause of leakage has been attributed to a cracked stellite weld in the body seat ring. The weld was made in 1974 to repair an axial crack across the stellite inlay which was discovered during a planned valve inspection that year.

Analysis of Occurrence Under design basis loss of coolant accident conditions (LOCA), the containment isolation valves function to limit the leakage out of the containment structure to less than one (1) weight percent of the contdinment atmosphere per day.

Conformance to this criteria assures that the release limits set forth in 10CFR100 will not be exceeded. The test results demonstrated that the leakage through valves NS03A and NS038 was at least 3 5 weight percent per day of the containment volume at approximately a four (4) psig differential pressure, i

l

, i

'Aspdr^ table Occurrence No. 50-219/78-18-1T Paga 3 Septcmbar 29, 1978 4

Corrective Action Necessary repairs will be performed during the ongoing refueling maintenance outage. A complete investigation of the MSIV failures is being conducted.

At the conclusion of the investigation, a detailed report will be submitted to the Plant Operations Review Committee who will determine if further corrective action is necessary.

Failure Data Manufacturer: Atwood & Morrill Co.

Type: Angle mounted globe valve Size: 24" diameter e

f 4

, , , , - - - r --

< w