05000414/LER-1997-001, :on 970103,maint Found Nitrogen Supply Isolation Valves for Power Operated Relief Valve (PORV) 2SV-1 Closed.Caused by Poor Work Practices.Nitrogen Isolation Valves for 2SV-1 & 2SV-13 Opened
| ML20134H020 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 02/03/1997 |
| From: | Kimball D, Mccollum W DUKE POWER CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| LER-97-001, LER-97-1, NUDOCS 9702110121 | |
| Download: ML20134H020 (6) | |
| Event date: | |
|---|---|
| Report date: | |
| 4141997001R00 - NRC Website | |
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Duke hauer Company waitog g ug(gjiy, jg Catawba Nudear Generation (Wpartment Vite fresident M0 ConcordRoad (WL1)&11LN Omcc
)urk. SClJ'in (yt1gy1313;Jz,x DUKEPOWER Febuary 3,1997 I
U.S. Nuclear Regulatory Commission Document Control Desk Washington, D.C. 20555
Subject:
Catawba Nuclear Station Docket No. 50-414 LER 414/97-001 l
r Gentlemen:
Attached is Licensee Event Repori e %.: gen Supply To Two Main Steam Power Operated Relief Valves Was isolated.
This event is considered to be of no significance with respect to the l
j health and safety of the public.
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Very truly yours,
/..
W. R. McCollum, Jr.
1 Attachment cc:
Mr. L.A. Reyes INPO Records Center Administrator, Region 11 700 Galleria Place U.S. Nuclear Regulatory Commission Atlanta, GA 30339-5957 101 Marietta St., NW, Suite 2900 l
Atlanta, GA 30323 l
Mr. P. S. Tam John Hoffman U.S. Nuclear Regulatory Commission Marsh & McLennan, Inc.(Nuclear)
J Office of Nuclear Reactor Regulation 301 Tresser Blvd.
/
9l Washington, D.C. 20555 Stamford, CT 06904 Mr. R. J. Freudenberger 7
NRC Resident inspector
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Nitrogen Supply To Two Main Steam Power Operated Relief Valves Was Isolated
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EVENT DATE (5)
LER NUMBER W REPORT DATE (7)
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ABSTRACT (Limit to 1400 spaces, i.e. approximatelyfifteen single space typewritten lines)(l6)
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i Unit Status: Unit 2 - mode 1, power operation, 100% power.
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Event Description
On January 3,1997, during routine maintenance to replace a f
low nitrogen cylinder, maintenance found the nitrogen supply isolation valves l
for power operated relief valve (PORV) 2SV-1 closed.
Operations instructed I
maintenance to open the nitrogen supply isolation valves to 2SV-1 and check i
the remaining three unit two and all four unit one PORW.
The nitrogen j
supply isolation valves for 2SV-13 were found closed, and opened according to Operations' instructions.
The remaining PORV nitrogen supply isolation valves were found open.
Root Cause:
The root cause of this event is poor work practices in that the test procedure was not followed correctly.
A contributing factor is performance of multiple actions in a test procedure step.
Corrective Action
Nitrogen isolation valves for 2SV-1 and 2SV-13 were opened. The remaining unit 2 and all four Unit 1 PORV nitrogen isolation l
valves were verified open. The individuals involved in this event were i
counseled. PT/1(2)/A/4200/31A, SG PORV and block valve D/P stroke test, will be revised to included separate actions for each valve manipulation.
To 4
prevent recurrence Engineering will review test procedures for steps j
reg' tiring multiple actions separated by time or distance and make changes as j
necessary, i
.U S fdUCLEAR REGULATORY COMMISSION (6 APPROVED OMB NO 3154 0104 Bd)
EXPlRES 5/3195 ESTIMATED BURDEN PER RESPONSE TO COMPLY WITH THiS LICENSEE EVENT REPORT (LER)
INFORMATION COLLECTION REQUEST. 50.0 HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE INFORMATION AND RECORDS TEXT CONTINUATION umAoEuENT eRmCs cuNes m4>. u.S. NUCLE AR REoutATORv COMMISSION. WASHINGTON. DC 20555 0001. AND TO THE PAPERWORK REDUCTION PROJECT (3150-0104). OFFICE OF MANAGEMENT AND BUDGFT WASHINGTON DC PM03 FOCILITY NAME (1)
DOCKET NUMBER (2)
LER NUMBE'H (6)
PAGE (3)
YEAR SEQUENTIAL REVISION NUMBFA NUMRER Catawba Nuclear Station, Unit 2 05000414 97 001 00 2 OF 5 BACKGROUND l
A safety related power-operated relief valve (PORV) [EIIS:RV) is provided in the safety grade portion of each main steam (SM) [EIIS:SB] line upstream of the main steam isolation valve [EIIS:ISV).
The PORVs are normally controlled by instrument air (VI) [EIIS:LD].
If VI is lost a safety grade mode of operation is provided by the use of a nitrogen control system to open the PORVs in the event of a tube rupture concurrently with the loss of offsite power.
There are four PORVs one per S/G, two in each vital area, that have independent nitrogen supplies with solenoids and controllers powered from independent essential electrical trains.
Technical specification (T/S) 3.7.1.6 requires three SG PORVs and associated remote manual controls, including the safety-related gas supply systems, to be operable in modes 1, 2, 3, and 4(when SGs are being used for decay heat removal).
With one less than the required SG PORVs operable, T/S require the inoperable SG PORV to be restored to operable status within 7 days; or be in at least hot standby within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in hot shutdown within the following 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and place the required ND loop in operation for decay heat removal.
EVENT DESCRIPTION
i December 22, 1996 The test coordinator and assistant test coordinator performed PT/2/A/4200/31A, SG PORV and Block Valve D/P stroke test, used to demonstrate the ability of the SG PORVs to open under manual control with nitrogen as the safety related supply.
January 3, 1997 The control room received a low nitrogen cylinder alarm on 2SV-1 and dispatched maintenance to replace the nitrogen cylinder.
When replacing the nitrogen cylinder, IP/2/A/3030/13, Procedure for Checking and replacing SG PORV Nitrogen Cylinders, has the maintenance technician close the nitrogen bottle isolation valve.
When the technician prepared to isolate the nitrogen cyl.inder he found the isolation valve already closed.
He checked the second cylinder and found the nitrogen isolation valve closed.
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NRC FC3M 3664 U S. NUCLEAR REGULATC3Y COMMISSION (6-APPROVED OMB NO. 31540104 89)
EXPl*tES.5/3 U95 ESTIMATED BURDEN PER RESPONSE TO COMPLY WITH THis LICENSEE EVENT REPORT (LER)
INFORMATION COLLECTION REQUEST: 50.0 HRS. FORWARD COMMENTS TEXT CONTINUATION REGARDING BURDEN ESTIMATE TO THE INFORMATION AND RECORDS u=AGEuENT BRwCmMNBB m4x u S NuCtEAR riEGutATORY i
COMMISSION, WASHINGTON. DC 205554001, AND TO THE PAPERWORK REDUCTION PROJECT (3150-0104h OFFICE OF MANAGEMENT AND BilDGET WASHINGTON DC P0601 FCCILITY NAME (1)
DOCKET NUMBER (2) tER NUMBER f6)
PAGE (3)
YEAR SEQUENTIAL REVISION NtlMBFA NUMAFA Catawba Nuclear Station, Unit 2 05000414 97 t
001 00 3 OF 5 i
i The control room was notified that the nitrogen isolation valves for 2SV-1 were found closed.
Operations instructed maintenance to open 1
2SV-1 nitrogen valves and check the remaining unit two nitrogen isolation valves and the nitrogen isolation valves for each unit one PORV.
Maintenance found the nitrogen supply to 2SV-13 also closed and opened the valves according to Operations' instruction.
1 CONCLUSION The root cause of this event is poor work practices in that the test procedure was not followed correctly.
The test coordinator and assistant coordinator did not use the tools for flawless human performance to ensure that all actions were performed as each procedure step was completed.
A contributing factor is performance of multiple actions in a test procedure step.
To complete procedure steps for opening and closing the air and nitrogen isolation valves the test coordinator and assistant coordinator must perform multiple actions, separated by time and distance, in one procedure step.
The non-licensed test coordinator and assistant test coordinator believe that they opened the nitrogen valves at the conclusion of the test.
Since the procedure required multiple valve manipulations in two different physical locations it is likely the individuals lost track.
There was no willful intent not to follow the procedure.
The test procedure will be revised to include specific steps for each valve manipulation.
To prevent recurrence Engineering will review procedures for steps requiring multiple actions separated by time or distance and make changes as necessary.
The controlled access log entries from 12/22/96 to 01/03/97 for the PORV vital areas were reviewed to determine the reasons for the entries.
No other entries were associated with the PORVs nitrogen supply.
Therefore, it was concluded that the valves were most likely left closed after completion of the periodic test on 12/22/96.
There are no NPRDS reportable equipment failures associated with this event.
A review of the operating experience database for the twenty four months preceding this event did not identify any events in which T/S surveillance 3.7.1.6 had been violated.
Additionally, this review did not identify any
similar events
One Licensee Event Report (LER) (414/96-002) with the same cause was found. The previous event did not involve the same equipment, nor
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NRC FORM 306A U S. NUCLEAR REGULATORY COMMISSION (6-APPROVED OMB NO. 31540104 Bd)
EXPIRES 5/31/95 ESTIMATED DURDEN PER RESPONSE TO COMPLY WITH TH!S LICENSEE EVENT REPORT (LER)
INFORMATION COLLECTION REQUEST: 50.0 HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE INFORMATION AND RECORDS TEXT CONTINUATION uANAGEMENT eRmCH <uNes rm>. u S. NUCLEAR REGutATORv COMMISSION, WASHINGTON, DC 205554001. AND TO THE PAPERWORK REDUCTION PROJECT (31504104). OFFICE OF MANAGEMENT AND I
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F ACluTY NAME (1)
DOCKET NUMBER (2)
LER NUMBER (6)
PAGE (3)
YEAR SEQUENTIAL REVISION l
NUMBER NUMRFR Catawba Nuclear Station, Unit 2 05000414 97 001 00 4 OF 5 would the corrective actions associated with the previous event affected or prevented the current event.
This event is not considered recurring.
1
CORRECTIVE ACTIONS
Immediate 1)
The nitrogen isolation valves for PORVs 2SV-1 and 2SV-13 were op(: ed.
2)
The individuals involved were counseled.
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Planned l
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1)
PT/1(2)/A/4250/01C will be revised to included separate actions for l
each valve manipulations.
2)
Engineering will review test procedures for steps requiring multiple actions separated by time or distance and make changes as necessary.
3)
Engineering will review the results of the current re-validation of UFSAR chapter 15 SG tube rupture accident analysis and revise the safety analysis associated with this LER if appropriate.
SAFETY ANALYSIS
During a SG tube rupture event, assuming worst case conditions such as loss of offsite power and no available VI leading to a loss of the atmospheric and condenser dumps, the PORVs (and the attendant assured nitrogen sources) would normally have to be relied upon to cool down the primary side in order to allow primary side depressurization within the subcooled zone.
This primary side depressurization is the mechanism by which the primary to secondary leakage is stopped.
The termination of leakage is important to prevent radioactive material from escaping through the main steam safety valves (and condenser dump valves if available) and to prevent SG overfilling.
During the period in question, two of the four SG PORVs were fully operable, and the other two were available with the exception of their backup nitrogen sources.
According to up-dated final safety analysis report (UFSAR) Chapter 15, the worst case single failure for a SG tube rupture accident is a stuck open PORV on the faulted generator. In the event that VI was not available, this worst case scenario would still leave one PORV controlled from the control room to start the primary side depressurization, The other two PORVs would be operated locally by an operator in communication with the control room via emergency sound powered jacks at
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EXP1RES 5/31895 ESTIMATED BURDEN PER RESPONSE TO COMPLY WITH THIS UCENSEE EVENT REPORT (LER)
INFORMATION COLLECTION REQUEST: 60.0 HRS FORWARD COMMENTS 1
REGARDING BURDEN ESTIMATE TO *...E INFORMATION AND RECORDS i
TEXT CONTINUATION uwAGEMENT eRmCs <MNes nm u S NUCLEAR REGutATORv COMMISSION, WASHINGTON. DC 20$$$4001, AND TO THE PAPERWORK REDUCTION PROJECT (315H104). OFFICE OF MANAGEMENT AND 1
RUDOFT WA4HINGTON DC P0501 FACILfiY NAME (1)
DOCKET NUMBER (2)
LER NUMBER (6)
PAGE (3)
YEAR SEQUENTIAL 4-REVISION NUMBFA
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NUMBER Catawba Nuclear Station, Unit 2 05000414 97 001 00 5 OF 5 each valve location.
This provision is delineated in the SG tube rupture emergency procedure.
Calculations to confirm that the radiological consequences of a SG tube rupture are within the appropriate guidelines are currently being re-validated by t site and general office accident analysis Engineering groups as part of our review of the UFSAR.
The results of this re-validation may require a change to this safety analysis.
This LER will be revised if appropriate.
The health and safety of the public were not affected by this incident.
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