05000530/LER-1998-002-02, :on 980814,B Train H Recombiner Was Noted Inoperable Due to cross-wired Power Receptacle.Cause of Event Is Under investigation.Cross-wired Power Supply Receptacle for B Train H Recombiner Was re-wired
| ML17313A596 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 09/14/1998 |
| From: | Marks D ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR |
| To: | |
| Shared Package | |
| ML17313A595 | List:
|
| References | |
| LER-98-002-02, LER-98-2-2, NUDOCS 9809230028 | |
| Download: ML17313A596 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2) 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(viii)(B) 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 5301998002R02 - NRC Website | |
text
LlCENSEE EVENT REPORT (LER)
ACIUTYNAME(1)
Palo Verde Unit 3 DOCKET NUMBER(2)
PAGE (3) 0 5
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"B"Train H dro en Recombiner Ino erable Due to Cross-Wired Power Rece tacle EVENT DATE 6 MONTH DAY YEAR LER NUMBER 6 SEOVBNTIAL NUMBER REVIQON NUMBER REPORT DATE MONTH DAY YEAR OTHER FACILITIESINVOLVED 6 T NUMBERS FAQUTYNAMES 0
8 1
4 9
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8 0
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REPORT IS SUBMITTEDPURSUANT TO THE REQUIREMENTS OF 10 CFR g: (Checir one or more ot the following)(1 1)
MODE (6)
LEVEL(10) 1 P
P 20A02(b) 20.45(a)(1)(i) 20A05(a)(1)(ri) 20A05(a)(1)(iii) 20.405(a)(I)(ntj 20.405(a)(1)(v) 20.45(c) 50.36(c)(1)
- 50. 36(c)(2) 50.73(.)(2)n 50.73(a)(2)(s) 50.73(a)rW-)
UCENSEE CONTACT FOR TIBS LER (12) 50.73(a)(2)(rr) 50.73(a)(2)(v) 50.73(a)(2)(vir) 60.73(a)(2) (viii)(A) 50.73(a)(2)(viii)(B) 50.73(a)(2)00 73.71(b)
'73.71(c)
OTHER (Specify in Abstract below and in Text, NRC Form E
Daniel-G. Marks, Section Leader, Regulatory Affairs COMPLETE ONE UNE FOR EACH COMPONENT FAILUREDESCRIBED INTHIS REPORT EPHONE NUMBER 6
0 2
3 9
3 6
4 9 2 (13)
CAUSE
SYSTEM MANUFAC.
TURER REPORTABLE TO NPRDS
CAUSE
SYSTEM COMPONENI'ANUFAC.
TURER REPORTABLE TO NPRDS B
B B RCPR3 4
4 SUPPLEMENTAL REPORT EXPECTED (14)
X YES (6 yes, complete EXPECTED SUBMISSON DATE)
TRACT (UmittO 1400 SPaCeS. Le. ~ aPPrOXlmately friteen Single SPaCe ypeWWntten lrnea) (I6)
EXPECTED SUBMISSON DATE (1 5)
MONTH DAY YEAR 1
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8 On August 14, 1998, at approximately 1600 MST, Palo Verde Unit 3 was in Mode 1
(POWER OPERATION), operating at 'approximately 100 percent power when testing revealed that the power supply receptacle for the "B" train Hydrogen
'ecombiner was cross-wired.
The power supply receptacle was configured such that had it been utilized, the blower motor of the supplied Hydrogen Recombiner would have rotated in the reverse direction.
Improved Technical Speci.fication, Limiting Condition for Operation 3.6.7 was entered on August 134 1998 at approximately 1700 MSTA and was exited at approximately 1740
- MST, on August 14r 1998'hen the cross-wired configuration was corrected.
Preliminary investigation results suggest that: the receptacle has been cross-wired since October, 1986.
All other Hydrogen Recombiner power supply receptacles were tested and veri.fied to be wired correctly.
No previous similar events have been reported pursuant to 10CFR50.73 in the past three years.
'T)80923002S 980914 PDR ADOCK 05000530 S
LICENSEE EVENT REPORT (LER) TEXT CONTINUATION AQUlYNAME Palo Verde Unit 3 DOCKET NUMBER YEAR LER NUMBER SEQUEN11AL NUMBER RENSION NUMBER PAGE 1.
REPORTING REQUIREMENT
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This LER (50-530/98-002-00) is being submitted pursuant to 10 CFR 50.73(a) (2) (i) (B), an operation or condition prohibited by the plant's Technical Specification.
Specifically, the power supply receptacle (RCP) for the "B" train Hydrogen Recombiner (HP)(BB) was cross-wired resulting in equipment inoperability in excess of the Technical Specification allowed outage time.
Also, prior to implementation of Improved Technical Specification on August 13, 1998, there was no Limiting Condition For Operation (LCO) by which Unit 3 could operate without at least one Hydrogen Recombiner operable.
Therefore, during the periods of time that the "B" train receptacle was cross-wired, and the redundant "A" train Hydrogen Recombiner was inoperable, or those times when the Hydrogen Purge system (HP)(BB) system was inoperable, the plant was in Technical Specification 3.0.3.
Note: Improved Technical Specification 3.6.7 Condition B allows for both Hydrogen Recombiners to be inoperable up to seven days provided the Hydrogen Purge system is available.
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EVENT DESCRIPTION
On August 14, 1998, at approximately 1600 MST, Palo Verde Unit 3 was in Mode 1
(POWER OPERATION), operating at approximately 100 percent power when testing revealed that the power supply receptacle for the "B" train Hydrogen Recombiner was cross-wired.
The power supply receptacle was configured such that had the it been utilized, the blower motor of the supplied Hydrogen Recombiner would have rotated in the reverse direction.,
Improved Technical Specification, Limiting Condition for Operation 3.6.7 was entered until the wiring configuration was corrected and demonstrated operable at approximately 1740 MST, on August 14, 1998.
Preliminary investigation results suggest that the receptacle has been cross-wired since October,
- 1986, when the electrical terminations were inspected during plant start-up.
Unit 1 and 2 Hydrogen Recombiner power supply receptacles were tested and verified to be wired correctly.
LICENSEE EVENT REPORT (LER) TEXT CONTINUATION ACulYNAME Palo Verde Unit 3 DOCKET NUMBER YEAR LER NUMBER SEQUEN1lAL NUMBER RPAQON NUMBER PAGE 0
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3.
ASSESSMENT OF THE SAFETY CONSEQUENCES AND IMPLICATIONS OF THIS EVENT:
The hydrogen recombiners provide for controlling the bulk hydrogen concentration in containment (NH) to less than the lower flammable concentration of 4.0 percent by volume following a Loss-of-Coolant design basis accident (DBA).
The control of hydrogen concentration:
- 1) prevents a containment-wide hydrogen burn, thus ensuring the pressure assumed in the analysis are not exceeded and minimizing damage to safety related equipment located in containment,
- 2) ensures containment pressure would not exceed the design basis pressure used in the structural design of containment, and 3) ensures the maximum leakage from containment during hypothetical event would remain within 10 CFR 50 appendix J requirement.
During the period of time the "B" train Hydrogen Recombiner was inoperable=
due to the cross-wired power supply receptacle, the "A" trai.n Hydrogen Recombiner and backup system (i.e. the Hydrogen Purge system) were available to control containment hydrogen levels within design limits had they been needed.
Unavailability of either the "A" train Hydrogen Recombiner or the backup Hydrogen Purge system was limited to brief periods during the performance of surveillance testing or periodic maintenance.
During the period of time the "B" train Hydrogen Recombiner was inoperable, there was at least one system available at all times to control Hydrogen in the containment.
There were no adverse
safety consequences
as a result of this event.
The event did not result in any challenges to the fission product barriers or releases of radioactive materials.
This event did not adversely affect the safe operation of the plant or the health and safety of the public.
4.
CAUSE OF THE EVENT
APS is investigating this event in accordance with the Corrective Action Program and will provide the results and findings of the investigation in a supplement to this LER.
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STRUCTURES I SYSTEMS g OR COMPONENTS INFORMATION The Containment Hydrogen Control System (HP)(BB) consists of containment hydrogen recombiners, gas analyzers, and post-accident hydrogen purge exhaust system. It provides equipment necessary to prevent the hydrogen concentration in the containment from exceeding 4 percent by volume following a loss-of-coolant accident (LOCA).
LICENSEE EVENT REPORT (LER) TEXT CONTINUATION ACILITYNAME Palo Verde Unit 3 DOCKET NUMBER YEAR LER NUMBER SEQUENTIAL NUMBER REVISION NUMBER PAGE 0
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Two 1008 capacity independent external hydrogen recombiners are shared among the three units.
Each consists of controls, a power supply (JX),
and a recombiner located in the Auxiliary Building (NF).
Recombination is accomplished by heating a hydrogen air mixture above 1150'F.
The resulting water vapor and discharge gases are cooled prior to discharge from the recombiner.
Air flows through the unit at 50 cubic feet per minute with a 5 hp centrifugal blower (BLO) in the unit providing the motive force.
A single recombiner is capable of maintaining the hydrogen concentration in containment below the 4.0 percent flammability limit.
Two recombiners are provided to meet the requirement for redundancy and independence.
Each recombiner is powered from a separate Engineered Safety Features
- bus, The post-accident hydrogen purge exhaust aiz filtration unit (AFU)(FLT) serves as a backup to the hydrogen recombinez and can be used to control Hydrogen concentration in the containment.
It is a portable unit which can be connected to any of the three plant units as needed.
It filters the potentially radioactive particulate matter and iodine from the air.,
6.
CORRECTIVE ACTIONS TO PREVENT RECURRENCE:
The cross-wired power supply receptacle for the "B" train Hydrogen Recombiner was re-wired and verified to be correct at approximately 1740 MST, on August 14, 1998.
All other Hydrogen Recombiner power supply receptacles were tested and verified to be wired correctly.
APS is investigating this event in accordance with the Corrective Action Program.
Additional corrective actions will be developed based upon the findings of the investigation.
APS will provide the corrective actions in a supplement to this LER.
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PREVIOUS SIMILAR EVENTS
No other previous events have been reported pursuant to 10 CFR 50.73 in the last three years.