05000266/LER-2002-002, A-Train Reactor Protection Cable Routed in B-Train Cable Trays
| ML023380127 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 11/22/2002 |
| From: | Cayia A Nuclear Management Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NRC 2002-0105 LER 02-002-00 | |
| Download: ML023380127 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(v)(B), Loss of Safety Function - Remove Residual Heat 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2) |
| 2662002002R00 - NRC Website | |
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C oNu Committed la Nluclear Excelle Nuclear Management Company, LLC Point Beach Nuclear Plant 6610 Nuclear Road Two Rivers, WI 54241 NRC 2002-0105 November 22, 2002 Document Control Desk U.S. NUCLEAR REGULATORY COMMISSION
- - Mail Station P1-137 Washington, D.C. 20555 10 CFR 50.73 Ladies/Gentlemen:
Docket Number 50-266 Point Beach Nuclear Plant, Unit I Licensee Event Report 266/2002-002-00 Unit I A-Train Reactor Protection Cable Routed in B-Train Cable Trays Enclosed is Licensee Event Report 266/2002-002-00 for the Point Beach Nuclear Plant, Unit 1. This LER is submitted to document the discovery that an A-Train safety injection signal cable was routed in B-Train cable trays. This cable routing non-conformance resulted in a condition prohibited by the Technical Specifications and was determined to be reportable in accordance with 10 CFR 50.73(a)(2)(i)(B). This condition has been corrected.
There are no new commitments in this report.
If you have questions concerning the information provided in this report, please contact Mr. C. W.
Krause at (920) 755-6809.
Sin Ire A.
. &yia\\
Si ice Prdent Enclosure cc:
NRC Regional Administrator NRC Resident Inspector NRC Project Manager PSCW V'
NRC FORM 366 U.S. NUCLEAR REGULATORY APPROVED BYOMB NO. 3150-0104 EXPIRES 7-31-2004 (7.2001)
COMMISSION Estimated burden per response to complywith this mandatory information collection request 50 hours5.787037e-4 days <br />0.0139 hours <br />8.267196e-5 weeks <br />1.9025e-5 months <br /> Reported lessons learned are incorporated into the licensing process and fed back to industry Send comments regarding burden estimate to the Records Management Branch (T.6 E6), US Nuclear Regulatory Commission, Washing]ton. DC 2055-01,or byintemet e-LICENSEE EVENT REPORT (LER) mail to bjsl nrc govand to the Desk Officer, Officeoi ofnformaton and Regulatory Affairs, NEOB-10202(3150-0104), Office of Management and Budget, Washington. DC20503 If a (See reverse for required number of means used to impose information collection does not display a currently valid OMB control digits/characters for each block) number, the NRC may not conduct or sponsor, and a person Is not required to respond to, the Information collection FACii ITY NAMP III nrCKFT NIIMRFR 121 PAr.F 131 POINT BEACH NUCLEAR PLANT UNIT I 05000266 l
1 OF 4 TITLE (4)
Unit 1 A-Train Reactor Protection Cable Routed in B-Train Cable Trays EVENT DATE (5)
LER NUMBER (6)
REPORT DATE (7)
OTHER FACILITIES INVOLVED (8)
IFACILITY NAME DOCKET NUMBER MO DAY YEAR YEAR NUMBER NO MO DAY YEAR 05000 m
FACILITY NAME DOCKET NUMBER 09 25 2002 2002 - 002 - 00 11 22 2002 05000 OPERATING THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFRI: (Check all that apply) (11)
MODE (9) 6 20.2201(b)
_ 20 2203(a)(3)(i) 50 73(a)(2)(ii)(B) 50 73(a)(2)(ix)(A)
POWER 20 2201(d) 20 2203(a)(4)
_ 50 73(a)(2)(m) 50 73(a)(2)(x)
LEVEL (10) 000 20.2203(a)(1)
_ 50 36(c)(1)(i)(A) 50 73(a)(2)(iv)(A) 73 71 (a)(4)
__ 20.2203(a)(2)(i) 5_ 0.36(c)(1)(ii)(A) 50 73(a)(2)(v)(A) 73.71 (a)(5)
W 20.2203(a)(2)(iiL 50 36(c)(2) 50.73(a)(2)(v)(B)
OTHER Specify In Abstract below or in 20.220(a)(2)(iii) 50 46(a)(3)(ii) 50 73(a)(2)(v)(C)
NC Form 366A 20.2203(a)(2)(iv)
_ 50.73(a)(2)(i)(A) 5_ 0.73(a)(2)(v)(D)
__ 20.2203(a)(2)(v)
X 50.73(aX2)(i)(B) 5_ 0.73(a)(2XvII)
(vu )
202203(a)
(2)(vI -5 73(a)(2)i)(C)
_ 50.73(a)(2)(v50)(A)
[3t 2fiG ub 20.2203(a)(3)(li) 50 73(a)(2)(i)(A) 50.73(a)(2)(vm)(B) X LICENSEE CONTACT FOR THIS LER (12)
NAME lTELEPHONE NUMBER (Indlude Area Code)
Charles Wm. Krause, Senior Regulatory Compliance Engineer l
(920) 755-6809 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)
MANU-REPORTABLE MANU-REPORTABLE
CAUSE
SYSTEM COMPONENT FACTURER TO EPIX
CAUSE
SYSTEM COMPONENT l FA CTURER TO EPIX SUPPLEMENTAL REPORT EXPECTED (14) iSUBMI ONTH DAY YEAR SUBMISSION lYES (If es, complete EXPECTED SUBMISSION DEE).
NO DATE (15) ll ABSTRACT (Limit to 1400 spaces, i.e., approxmately 15 single-spaced typewntten lines) (16)
While completing a plant modification for rerouting of cables, NMC personnel identified an A-Train engineered safeguards features (ESF) actuation circuit installed in a B-Train cable tray. This circuit provides an A-Train SI actuation signal to the A-Train reactor protection system. The A-Train SI actuation signal is also routed to the B-Train reactor protection through a separate cable. This routing discrepancy has existed since original plant construction. This condition is being reported as a condition prohibited by the Technical Specifications.
The other two Unit 1 cables associated with this unique cable scheme were routed correctly. The cable routing for Unit 2 was verified correct during the unit's Spring 2002 refueling outage. This cable routing discrepancy was corrected as part of the ongoing modification and completed during the Unit I Fall 2002 refueling and maintenance outage. A safety assessment concluded that this cable separation violation had no impact on the public health and safety and did not involve a safety system functional failure.U.S. NUCLEAR REGULATORY COMMISSION (7-2001)
LICENSEE EVENT REPORT (LER)
TEXT CONTINUATION FACILITY NAME (1)
DOCKETNUMBER (2)
LER NUMBER (61 PAGE 3 YEAR SEQUENTIAL REVISION Point Beach Nuclear Plant Unit 1 05000266 NUMBER NUMBER 2 OF 4 2002 002 00 TEXT (If more space is required, use additional copies of NRC Form 366A) (17)
Event Description
On September 25, 2002 during the performance of a plant modification (MR 00-003), NMC personnel discovered that a Point Beach Nuclear Plant (PBNP) Unit 1 A-Train reactor protection {JC} cable {CBL1} was routed in B-Train cable trays {TY}. At the time of discovery, PBNP Unit 1 was in Mode 6 for its 27th refueling outage. Modification MR 00-003 was being performed to correct previously identified reactor protection cable train separation concerns in the conduits
{CND) and cable trays above engineered safety features (ESF) {JE} cabinets (CAB} I C157 and 1 C167. These cabinets and trays are located in the cable spreading room {NA}. While pulling cables out of 1 C157, to reroute reactor protection (RP) cable ZB1NB105A, a B-Train cable, cable ZAINA105A, an A-train cable, was found in the same conduit (DM-1). This is a Train B conduit. Cables ZBlNBI05A and ZAINA105A are part of the unique four-cable scheme associated with a safety injection (SI) signal. Actuation of one train of ESF will cause a reactor trip signal on both trains. The complete scheme is shown below. Cable ZA1 NAI05A was designed to be routed between A-train cabinets in A-Train cagle trays. However, finding that cable in conduit DM-1 indicates that it is routed in B-train cable trays, which is not in accordance with PNBP design requirements.
A-Train ESF B-Train ESF 1 Cl57 1C167 ZAI NA105A 7/<ZBlNB1 06A
/ZBlNB105A 1C153 l
C154 l
C6 C164 A-Train RP B-Train RP Upon discovery of this routing discrepancy, a Corrective Action Program activity request was initiated (CAP 29532) to document the condition. The A-Train SI signal to the reactor protection system was declared inoperable due to improper cable separation. This condition affects Item 16 of Technical Specification Table 3.3.1, "Safety Injection Input from Engineered Safety Features Actuation System." That item is applicable only in Modes 1 and 2 and requires 2 trains to be operable. If a train is inoperable for greater than 18 hours2.083333e-4 days <br />0.005 hours <br />2.97619e-5 weeks <br />6.849e-6 months <br />, the reactor is required to be in Mode 3. PBNP Unit 1 was in Mode 6 at the time of this discovery; therefore, the action condition for this item was not applicable at the time of discovery. However, PBNP Unit 1 had operated in Modes 1 and 2 in the past with this existing train separation discrepancy. Therefore, in accordance with the requirements of 10 CFR 50.73(a)(2)(i)(B), PBNP Unit 1 had operated in a condition which was prohibited by the plant's Technical Specifications. As clarified in NUREG 1022, this LER is required even if the condition was not discovered until after the allowable time had elapsed and the condition was rectified immediately upon discovery.U S. NUCLEAR REGULATORY COMMISSION (7-2001)
LICENSEE EVENT REPORT (LER)
TEXT CONTINUATION FACILITY NAME (1)
DOCKET NUMBER 2.
LER NUMBER (6l PAGE 3 YEAR SEQUENTIAL REVISION Point Beach Nuclear Plant Unit 1 05000266 NUMBER NUMBER 3 OF 4 2002 002 00 TEXT (If more space is required, use additional copies of NRC Form 366A) (17)
Cause
Both the plant's Cable and Raceway Data System (CARDS) and the original Architect Engineer cable data sheets were reviewed for cable ZAl NA105A. Cable ZAl NA105A was listed as having the same routing as cable ZAl NA106A.
Cables ZA1 NA1 05A and ZA1 NA1 06A cannot have the same routing since cable ZA1 NAI 05A is routed to I C1 57 and cable ZA1 NA106A is routed to 1C167. This discrepancy had been noted in a 1998 condition report (CR 98-3944/
CAP020254). The conclusion drawn in the resolution of that condition report was that the ZAI NA1 05A cable must be routed in A-train cable trays to 1 C1 57 since the cable is physically located in the cabinet. However, the other end of the cable was not verified to check which cable tray/conduit cable ZAI NA1 05A was routed in when it left cabinet 1 C1 53.
Based on a review of plant modification and work order history, the routing of cable ZAI NA1 05A had not previously been modified from original construction. Therefore we have concluded the apparent cause of this discrepancy results from an original construction installation error.
Corrective Actions
An extent of condition assessment has been completed. As described in the 'Component and System Description" below, the four cables in this Si to reactor trip scheme are unique to the plant. The other two Unit 1 cables associated with this unique cable scheme have been visually verified as being routed correctly or were being rerouted in accordance with the plant modification. PBNP Unit 2 also has the same four-cable scheme. The cables from this scheme (ZC2NA105A, ZC2NA106A, ZD2NB105A and ZD2NB106A) were checked and verified to be appropriately routed following the completion of a separate modification (MR 00-004) during the Unit 2 2002 refueling outage.
An engineering change request (ECR) to MR 00-003 was initiated to correct the separation violation documented in this report. The ECR abandoned the existing cable and relabeled it as ABNO006. A new cable ZA1 NAI05A has been installed in dedicated A-train cable trays between 1C153 and IC1 57.
Component and System Description:
The engineered safety features actuation system detects plant conditions that require automatic ESF equipment operation, and actuates the appropriate ESF equipment when preset limits are reached. ESFAS subsystems monitor plant parameters indicative of different accidents. When the minimum number of channels of a monitored variable reaches a preset limit, trip bistables satisfy coincidence logic for an individual subsystem and the subsystem is automatically initiated. ESFAS subsystems include Si actuation. Among other things, a manual or automatic SI signal initiates a reactor trip through the reactor protection system. The SI actuation contacts that supply a signal to the reactor trip logic originate in each of the two ESFAS logic trains. Each ESFAS logic train supplies a reactor trip signal to both trains of reactor protection logic. This leads to a unique condition where the ESFAS logic A-Train is communicating with the RPS logic B-Train (as well as with the A -Train), and the ESFAS B -Train is communicating with the RPS A-Train (as well as with the B-Train). This condition does not create an electrical separation conflict between redundant trains because the inputs to reactor protection are channel-related. Within each train of reactor protection, the two inputs from SI actuation train A & B enter two separate channel-related racks. There, the inputs drive separately fused isolation relays. Additional information can be found in Section 7.3 of the PBNP FSAR..
Safety Assessment
The cables and cabinets addressed by this LER are all located in the cable spreading room (CSR), which is a vital protected area in the Point Beach Plant. The train separation violation identified in the event description would not by itself make the SI actuation signal input to the reactor protection inoperable. However, a initiating event such as a fireU.S. NUCLEAR REGULATORY COMMISSION (7-2001)
LICENSEE.EVENT REPORT (LER)
TEXT CONTINUATION FACILITY NAME 1 DOCKET NUMBER 2.
LERNUMBER(6l PAGE 3
))YEAR SEQUENTIAL REVISION Point Beach Nuclear Plant Unit 1 05000266 NUMBER NUMBER 4 OF 4 2002 002 00 TEXT (if more space is required, use additional copies of NRC Form 366A) (17) could have effected both the A-Train and B-Train which were found installed in the B-Train cable trays. The CSR is protected from significant fire events by both heat and smoke detectors and an automatic Halon fire suppression system. Thus the potential for an uncontrolled fire in the CSR is minimized. In addition, in accordance with 10 CFR 50 Appendix R safe shutdown requirements, the plant can be safely shutdown and maintained in a safe shutdown condition without the availability of the CSR equipment.
Notwithstanding these fire protection provisions, if a fire had initiated in the B-Train cable trays, it is probable that the circuits would have failed to an open circuit or could have short circuited. In the former case, the function of the ESF to RP would have been satisfied since this circuit scheme is designed as a "de-energize to trip' circuit and an open circuit would result in a reactor trip signal. If a hot smart short occurred in the cable tray and the circuit remained energized, it is likely that the B-train ESF signal cable to the A-Train RP would remain unaffected by the initiating fire and capable of completing the ESF to RP trip function.
Based on these considerations we have concluded that the health and safety of the public and plant staff was not impacted by the event. Since we have not identified any loss of safety function that resulted from this lack of adequate ESF to RP train separation, we have also concluded that this event did not involve a safety system functional failure.
Similar Occurrences:
A review of LERs submitted in the past three years identified no other events involving cross train separation events.
An older LER dated September 7, 1996 was identified which discussed main control board circuit separation.
LER NUMBER Title LER 266/96-007-00 Redundant Safety Related Circuits in Same Main Control Board Wireways