05000255/LER-1995-010, :on 950815,ESFA & Manual RT Occurred Following Isolation of PCS Leak.Caused by Less than Adequate Engagement of Tubing Section Into Compression Fitting. Replaced Failed Instrument Line: Difference between revisions

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#REDIRECT [[05000255/LER-1995-010, :on 950815,ESFA Resulted in Manual RT Following Isolation of Pcs.Replaced Failed Instrument Line]]
| number = ML20097J386
| issue date = 01/26/1996
| title = :on 950815,ESFA & Manual RT Occurred Following Isolation of PCS Leak.Caused by Less than Adequate Engagement of Tubing Section Into Compression Fitting. Replaced Failed Instrument Line
| author name = Smedley R, Vincent R
| author affiliation = CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.),
| addressee name =
| addressee affiliation = NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
| docket = 05000255
| license number =
| contact person =
| document report number = LER-95-010, LER-95-10, NUDOCS 9602020075
| document type = LICENSEE EVENT REPORT (SEE ALSO AO RO), TEXT-SAFETY REPORT
| page count = 6
}}
{{LER
| Title = :on 950815,ESFA & Manual RT Occurred Following Isolation of PCS Leak.Caused by Less than Adequate Engagement of Tubing Section Into Compression Fitting. Replaced Failed Instrument Line
| Plant =
| Reporting criterion = 10 CFR 50.73(a)(2)(iv)
| Power level =
| Mode =
| Docket = 05000255
| LER year = 1995
| LER number = 10
| LER revision = 0
| Event date =
| Report date =
| ENS =
| abstract =
}}
 
=text=
{{#Wiki_filter:l 4
Consumers Power rowenme MENNiAN5 MR0GRuss Palisades Nuclear Plant: 27780 Blue Star Memorial Highway, Covert, M149043 January 26,1996 1
U S Nuclear Regulatory Commission Document Control Desk W:shington, DC 20555 DOCKET 50-255 - LICENSE DPR PALISADES PLANT LICENSEE EVENT REPORT 95-010 ENGINEERED SAFETY FEATURE ACTUATION - MANUAL REACTOR TRIP DUE TO ISOLATION OF PRIMARY COOLANT SYSTEM LEAK-REVISED REPORT l
Licensee Event Report (LER) 95-010, Revision 1, is attached.
l This event was reportable to the NRC per 10CFR50.73(a)(2)(iv) as an event or condition that resulted in a manual actuation of an engineered safety feature.
SUMMARY OF COMMITMENTS This letter contains no new commitments. The scope of the previous comitment made in LER 95-010 was revised to more clearly reflect our intended corrective action. This corrective action has been completed. All commitments relating to LER 95-010 are closed.
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R hard W. Smedley Manager, Licensing CC Administrator, Region Ill, USNRC Project Manager, NRR, USNRC Resident inspector, USNRC - Palisades Att:chment 9602020075 960126 PDR ADOCK 05000255 S
PDR i
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e NRC Form 366 U.S. NUCLEAR REGULATORY COMMISSION
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/,PPROYED OM8 NO. 31604104 EXPIFtES: 8/31/86 LICENSEE EVENT REPORT (LER)
FACIUTY NAME (1)
DOCKET NUMBER (2)
PAGE(3)
P:lis: des Plant o
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O, o
s trrtfi4iLICENsEE EVENT REPORT 95-olo ENGINEERED SAFETY FEATURE ACTUATION MANUAL REACTOR TRIP FoLLoWING THE isolation oF A PRIMARY COOLANT SYSTEM LEAK - REVISED REPORT EYENT DATE (6)
LER NUMBER (6)
REPORT DATE (6)
OTHER F ACluTIES INVOLVED (8)
SEQUENTIAL REVISION FACluTY NAMES MONTH DAY YEAR YEAR NUMBER NUMBER MONTH DAY YEAR 0l6l0l0l0l l N/A 0l6l0l0l0l l 0l8 1l5 9
5 9l5
:- Ol1l0 ol1 0l1 2l6 9l6 N/A THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR O / Check one or more of the fotbwing)(11)
MO E(9 20.402fb) 20.406(cl X
60.731aH2Hev) 73.71(bl POWER 20 406(aH1HO 60.36tc)(1) 60.73(a)(2Hv) 73.71(c)
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OTHER (Spectfy in Abstract
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Olol0 20 *0*t1Hto 60 36'c)(2) 50.73(aH2)(va0 20 406(aH1HnD 50.7$aH2HO 60.73(aH2HviiOLA) below and in Text 20.406laH1 Hiv) 60.73(aH2Hl0 60 73(aH2HviliHB)20 406(all1Hv) 60.73(aH2Hliu 60.73(al(2Hz)
LICENSEE CONTAC1 FOR THIS LER (12)
NAME TELEPHONE NUMBER AREA CODE Robert A Vincent, Licensing supervisor 6l1l6 7l6l4l-l8l9l1l3 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)
M ANUF AC-REPORTABLE MANUFAC.
REPORTABLE
 
==CAUSE==
SYSTEM COMPONENT TURER TO NPRDS
 
==CAUSE==
SYSTEM COMPONENT TURER TO NPRDS AlB lTlBlG l
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SUPPLEMENT AL REPORT EXPECTED (141 MONTH DAY YEAR EXPECTED
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YES ut yes, compoete EXPECTED SUBMISSION DA TO
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I ADSTAACT lLhnft to 1400 spaces, Le., appronknetery fifteen singk space typewritten knes) (161 On August 15,1995, at 0248 hours, with the plant in hot standby condition and one control rod partitlly withdrawn, a 1/2" diameter primary coolant system (PCS) instrument line compression fitting in containment failed. The leak caused a pressure transmitter output to fail low and initiate a PCS low flow trip on one channel of the reactor protective system (RPS). The leak rate was cpproximately 12 gpm and the operations crew was immediately aware of the event based on control room indications and notifications from personnel in containment. During the closure of m:nual root valves to isolate the leak, additional PCS low flow trip channels were inadvertently affected. A manual reactor trip was initiated in anticipation of an automatic reactor trip on the combination of invalid low PCS flow inputs to the RPS. The cause of the leak was less than cd:quate engagement of a tubing section into a compression fitting during its assembly at some unknown time in the past. The cause for the reactor trip was the inadvertent closure of the wrong isolation valves due to several valves being mislabeled.
Tha corrective actions completed include replacement of the failed instrument line, the restoration and functionality check of the pressure transmitters, inspection and clean up of components in i
tha vicinity of the leak, and an evaluation of the generic implications of this event and similar industry experience events. A walkdown of all primary coolant system root valves is planned during the next cold shutdown period to ensure each valve is labeled correctly.
 
e Nnc conn assa u.s. HuctsAn neoutAtony coMuisSloN yess coig Arenoveo LICENSEE EVENT REPORT (LER) TEXT CONTINUATION l
4 4
1 FACLITV NAME (1) '
DOCKET NUMSEn (2)
LEn NUM9En (3)
YEAR PIlis des Plant o!5_
ol5lololol2l5l5 9l5 ol1lo ol1 ol2 0'
 
==EVENT DESCRIPTION==
On August 15,1995, at 0248 hours, with the plant in hot standby condition and individual l
control rod drop time testing in progress, the control room operators were alerted to several
)
indicstions that a small Primary Coolant System (PCS),[AB), leak had occurred in the containment building. The information received was: a smoke detector alarm in containment, a low PCS flow j
)
channel trip and alarm on the "B" channel of the Reactor Protective System (RPS), and an l
immsdiate phone call from personnel working in containment that a steam leak had suddenly i
occurred in the lower level of containment in a location near racks of numerous PCS instruments.
i Tha operators entered off normal procedure (ONP) 23.1, " Primary Coolant Leak", and -
l commenced plans to isolate the leak, [TBG). Several imrrediate actions were also taken at this l
tims including the estimation of the leak rate at approximately 12 gpm and the full insertion of I
ths partially withdrawn control rod.
Ths operations crew identified three manual valves that would need to be closed in order to l
t isolzte the PCS leak. From all indications the break was on the instrument line feeding the l
"ftilad-low" differential pressure transmitters, DPT-0112AB and DPT-011".BB, which provide stnam generator differential pressure indication in the control room as weit as input to the RPS low PCS flow trip circuitry. During this planning, it was also determbed that other differential prsssure transmitters and their associated "D" channel RPS low PCS flow trip channels would be affected by the closure of the selected isolation valves. For this rea son, the previously tripped RPS "B" channel for low PCS flow was placed in the bypass mode tu isolate the invalid low flow l.
trip on channel "B". This planned action would avoid a possible reactor trip on PCS low flow due to thn anticipated two out of four trip logic being satisfied upon leak isolation.
Upon arriving at the scene of the leak, the auxiliary operators closed the initial set of three valves. At this time, the operators were not aware that several manual root valves for the instruments involved were mislabeled. The leak rate did not change upon the closure of the vclves and the operators contacted the shift supervisor (SS) for further actions. The SS instructed the operators to physically walk down the tubing run to identify the proper isolation i
valves. The operators subsequently located and closed the remaining valve that provided full isolstion of the leak. The total inventory lost was approximately 800 gallons.
j At cbout this same time, the control room personnel observed additional unexpected PCS low flow pre-trips on RPS channels "A" and "C" and manually tripped the reactor. The RPS channels "A" and "C" low flow pre-trips had slowly evolved from the closure of the mislabeled valves and tha subsequent pressure decay of the trapped fluid in the sensing lines to the associated prassure transmitters. The manual. trip was initiated in anticipation of and prior to an automatic trip on PCS low flow due to the combination of invalid trip signals to the RPS channels. Based on the fact that the control rods'were all located at their lower electrical limit, approximately three inchts of withdrawal, the reactor trip was basically a necessary formality that did not significantly
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3 APPROY NO.
1 EXPtRES: 8/31/85 LICENSEE EVENT REPORT (LER) TEXT CONTINUATION
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rAcury NAme m oocm Nuween m LER NUMeER W PAGE W E
Ne$e vtAn Palistdes Plant -
olslololol2lsls sls ol1l0 ol1 ol3 ol5 or chgnge the plant configuration. The operators completed th'e post reactor trip actions and dstarmined that all plant equipment responded properly to the event. The NRC was notified of tha manual reactor trip per the four-hour nonemergency reporting requirements of 10CFR50.72(b)(2)(ii) at 0513 hours.
 
==CAUSE OF THE EVENT==
Thsro are two different occurrences that created the need to manually trip the reactor. The first occurrence was the failure of the instrument tube fitting which resulted in the PCS leak. The sscond event was the inadvertent closure of the wrong isolation valves to stop the bak, which resulted in two additional RPS low flow trip channels to fail low and necessitate a manual reactor l
trip.
FAILED INSTRUMENT TUBE FITTING 1
Following the isolation of the leak, it was determined that a section of 1/2" diameter instrument tubing had pulled out of a swagelock compression fitting. The instrument line is located at the bottom level of containment, 590' elevation, in the instrument air room. The inspection of the tubing and fitting indicated that the tubing had not been fully seated into the compression fitting during previous assembly. This was determined by the location of the permanent markings made by tha compression fitting ferrule on the outside diameter of the tubing. The markings were locatsd at the very end of the tubing indicating that the tubing had not been fully seated into the bora of the fitting prior to final fitting assembly. The expected location of the compression ferrule markings would be approximately 1/4" back from the leading edge of the tubing.
The tubing which had pulled out of the fitting had several bends located near the fitting that l
waro needed in order to route the tubing around an adjacent support beam. It is likely that the 1
tubing contacted the support beam and was unknowingly not fully seated in the bore of the l
compression fitting'during initial assembly and any subsequent reassemblies. A review of work order history did not identify when the associated fitting was last altered. The fitting may have j
remained untouched since initial plant construction because its location would not require it to be disturbed as part of routine or nonroutine maintenance or testing on the associated pressure transmitters. A team of plant personnel walked down approximately one hundred other accessible compression fittings in containment. No other tubing runs were observed to have simil2r interference problems or complex routing that could lead to less than adequate tubing engrgement.
L Failure of instrument tubing compression fittings has been the subject of several operating exptrience n,otices. Most notably, in 1991, a failed compression fitting at Oconee Unit 3 resulted in Inking 87,000 gallons into containment. The root cause for this failure was different and was dua to less than adequate compression of the mating ferrule. As a result of this 1991 operating i
exp2rience event, Palisades enhanced the training for plant personnel who assemble compression
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A YE NO O 1 8
EXPtRES: B/31/96 UCENsEE EVENT REPORT (LER) TEXT CONTINUATION FACR1TY NAME (1)
DOCKET NUMSER (2)
LER NUMBER (3)
PAGE (4) -
SEQUENTIAL REVISION YEAR NUM8ER NUMSER P:listdes Plant ol5lololol2l5l5 sl5 ol1l0 ol1 ol4 ols o'
fittings and also developed a formal checklist to be used during work activities. Also, an insp;ction of approximately one hundred compression fittings was completed during the 1993 rsfusling outage to evaluate the condition of a sample of fittings. Some minor discrepancies were obs:rved and the work controls for compression fitting maintenance were further enhanced.
CLOSURE OF THE WRONG ISOLATION VALVES Tha wrong valves were closed during isolation of the leak due to the mislabeling of two pairs of root valves within the set of steam generator E-50A differential pressure transmitters. The tags for tha two pairs of valves contained proper data, but were inadvertently placed on the incorrect velves at some unknown time in the past. Based on their location on the instrument line, the root valvss are not routinely manipulated to support maintenance or testing of individual components or tha PCS system. The root valves for the differential pressure transmitters are all verified to be opsn during the performance of system checklists prior to plant start-ups. However, due to their closs proximity to each other and their associated pressure transmitters, there would be no reason to suspect during the performance of the checklists that valve tags were placed on the wrong root valves. It is likely the tags were installed incorrectly due to personnel error.
 
==SAFETY SIGNIFICANCE==
The PCS leak of approximately 12 gpm was well within the 130 gpm capacity of the charging pumps and the PCS make-up systems. The physicallocation of the leak was quickly diagnosed and the leak was isolated within 1 hour and 20 minutes. The subsequent manual reactor trip was unsvsntful based on the fact that the plant was in the hot standby condition, the control rods w:ro already fully inserted to their electrical lower limit, and the PCS parameters of pressure and temparature remain stable during a trip from the hot standby condition. All plant equipment j
responded properly to the event and the equipment located adjacent to the leak did not suffer any adverse effects.
I Based on the evaluation of the failed tubing and actions taken to enhance compression fitting mrintsnance at Palisades, it is not deemed likely that other compression fittings will fail. Also, cny. future failures of tubing would result in analyzed conditions pertaining to the loss of a particular system fluid inventory or partial spray and flooding of other plant components, w
Bas:d on the evaluation of the mislabeled root valves, it is not likely that a significant event will 4
result from the manipulation of mislabeled root valves. Palisades Off-Normal and Emergency i
Op:rsting Procedures do not contain any significant root valve manipulations to minimize the conzsquences of a postulated accident. The tagged and labeled components in the plant that could require manipulation during off normal events have received adequate oversight during 1
l
 
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6 sI PPRovE oM No i
UCENSEE EVENT REPORT (LER) TEXT CONTINUATION l
FACluTY NAME til DOCKET NUMBER (2)
LIR NUMSER (3)
PAGE141 SEQUENTIAL REVISION 1
YEAR NUMBER NUMBER Palisades Plant ol5l0lolol2l5l5 9l5 ol1l0 ol1 ol5 ol5 0'
trcining and other license qualification efforts. Thus, the safety significant labels and tags in the plint are routinely used and verified to be correct. The likely extent of any root valve mislabeling which might be present, therefore, is judged to be very limited and not of safety significance.
CORRECTIVE ACTIONS TAKEN AND RESULTS ACHIEVEQ Tha following corrective actions have been completed:
1.
.The failed swagelock fitting and associated tubing were replaced usir:q the established Palisades guidelines for assembly of compression fittings.
2.
The differential pressure transmitters were restored to service and verified to be operating properly.
3.
The components and structures located in the general area of the leak were wiped down and i
inspected to ensure no damage occurred.
4.
A team of plant personnel walked down approximately one hundred other accessible compression fittings in containment. No other tubing runs were observed to have similar interference problams or complex routing that could lead to less than adequate tubing engagement.
5.
The labeling of all root valves associated with the PCS flow defferential pressure l
instrumentation has bean verified to be correct. New labels were installed as needed.
CORRECTIVE ACTIONS TO BE TAKEN All corrective actions have been completed.
P 4
i
}}
 
{{LER-Nav}}

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