05000285/LER-1980-001-03, /03L-0:800102,while Operating at Approx 98% Power, Breaker Feeding Containment Cooling Fan Motor VA-3B Tripped.Caused by Trip Units Out of Calibr.Units A&C Were Replaced,Calibr & Tested Satisfactorily

/03L-0:800102,while Operating at Approx 98% Power, Breaker Feeding Containment Cooling Fan Motor VA-3B Tripped.Caused by Trip Units Out of Calibr.Units A&C Were Replaced,Calibr & Tested Satisfactorily

ML19262C266
Person / Time
Site:	Fort Calhoun
Issue date:	01/07/1980
From:	Mueller R OMAHA PUBLIC POWER DISTRICT
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML19262C262	List: 05000285/LER-1980-001, Forwards LER 80-001/03L-0 05000285/LER-1980-001-03, /03L-0:800102,while Operating at Approx 98% Power, Breaker Feeding Containment Cooling Fan Motor VA-3B Tripped.Caused by Trip Units Out of Calibr.Units A&C Were Replaced,Calibr & Tested Satisfactorily
References
LER-80-001-03L, LER-80-1-3L, NUDOCS 8002080508
Download: ML19262C266 (4)

LER-1980-001, /03L-0:800102,while Operating at Approx 98% Power, Breaker Feeding Containment Cooling Fan Motor VA-3B Tripped.Caused by Trip Units Out of Calibr.Units A&C Were Replaced,Calibr & Tested Satisfactorily

Event date:
Report date:
2851980001R03 - NRC Website

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EVENT DESCRIPTION ANO PROBA8LE CONSEQUENCES h o

2 l On. January 2, 1980, while operstinz st sperexiestely C never, the brener faedi w I o ia lthe containment cooling fan =otor (7A-33) tripped.

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l occurred due to faulty trip units in the bresker f*eeding 7A-33.

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0=sha Public Power District Fort Calhoun Station Unit Ho. 1 Decket No. 05000235 IIR SC-001 Attach =ent No. 1 Safety Analrsis The Contain=ent Air Recirculation, Cooling and Filtering System at the Fort Calhoun Station Unit No.1 is so designed that no single failure can prevent the syste= frc= performing its designed function.

During this incident, the contain=ent cooling and filtering unit 7A-33 was rendered inoperable as a result of a faulty feeder breaker.

In addition, during subsequent operability testing of redundant contain=ent ecoling and filtering units, ECV h033 was found to be inoperable iue to a plugged orifice in the pneu=atic controller which feeds air to/frc= the valve's diaphram.

ECV h033 is the c =penent cooling water inlet valve which feeds the coeling coil for the con-tai--ar* ~^oling fan, 7A-73.

Fol10ving the failure of HCV 4033, diesel D1 was tested and verified operable and the Contain=ent Spray System, which is inde-pendent of and redundant to the Contain=ent Air Recirculation and Ccoling Syste=, was also fully operable during the incident.

This contain=ent spray 37ste= is designed for s tinimum heat re=cval capacity of 260 x 10~ 3TU/hr. vith a containment temperature of 233 F; this is the heat re=cval rate necessary to maintain the conta1=nent at=osphere below the designed pressure in ne even* af a 03A.

The 230 x 10 3TU/hr. heat rencval rate ccrresponds to a containment spray flow rate of 3L00 gp=.

This 3h00 sp= correspends to the case of =ini=u= flow rate - that is, three spray pu=ps starting and only one spray header available.

It is a point of interest to note that with two contain=ent spray pu=ps available and two spray headers - the contain=ent spray system is capable of supplying a flow rate of $100 gp=.

Thus, it is dee=ed that the Fort Calhoun Contain-

=ent Spray Syste= is, by itself, = ore than capable of supplying sufficient contain=ent cooling in the unlikely event of a 03A.

1944 542 At the time of the incident, 7A-33 was considered inoperable due to a faulty breaker and 7A-7D vas also considered inoperable since HCV h033 (the 00=ponent cooling water inlet valve) was not functioning as designed. However, the remaining and operable centain=ent eccling and filtering units 7A-?A and 7A-7C vere still capable of re=0Ving 210 x 10 3TU/hr. at DBA conditions, frc= the contain=ent at=csphere.

Thgsis755oftherequiredcontain=ent03Aheatre=cvalrateof280x 10 3TU/hr.

7A-7D vaa rendered inoperable as a result of the HC7 a033 c:=penent cooling vater valve failure.

However, the rav vater syste:

'g was operable and is a backup supply for cc=ponent c0 cling vater to the

.s 7A-73 cooling coil.

Thus, as far as the safety inalysis is conecrned, N-7A-70 could have been =anipulated to supply centainment c00 ling as de-m signed and the 03A heat re= oval rate of 250 x 10' 3TU/hr. could have been

=e by the COntain=ent Cooling and Recirculating fan units if required.

C=aha Public Power District Fort Calhoun Station Unit No. 1 Decket No. u5000235 an m r 3 vv-v0.,

Attach =ent No. 2

Corrective Action

Maintenance Order 3h06 was issued to = egger VA-33 fr0= the lead center and to check breaker trip settings.

The =otor meggered satis-factorily, however, the trip setting: for the A and C phases were found to be inaccurate and out-of-calibration as far as the long ti=e delay setting was concerned.

Consequently, two spare G.E. EC-2A trip units were installed as replacements in the breaker A and C phases.

The breaker was recalibrated and the trip setpoints were satisfactorily tested for proper operation. and the breaker was returned to service.

The contain=eni ecoling and recirculating fan, 7A-33 was prc=ptly returned to service and operated normally.

In addition, as a result of the failure of 7A-33, redundant c0=penents of the contain=ent cooling and recirculation system (in-cluding diesel D1) were tested for operability.

The following breakers for the equipment specified vere also tested (cycled) to ensure that their breakers vere operating satisfactorily:

SI-2A/23/2C H.P. SI ?u=ps SI-3A/33/3C Cent. Spray Pu=ps CH-1A/13/1C Charging Pumps 7A-3A Contain=ent Air ?.ecirculation 7A-TC/7D and Cccline Fan Units f?44'343 NOTT:

All equipment listed above contain breakers identical to that feeding 7A-33 All breakers operated satisfactorily.

However, during the re-dundant equip =ent operability testing of contain=ent cooling equip-

=ent, as required by Technical Specification 2.k. (1), HCV h033 failed to open fr0= the control *com switch HCV h033 is the 00=ponent ecoling vater inlet valve which supplies water to the cooling coil of the containment c0 cling fan VA-7D.

M.0. #3h07 vas written to correct this problem. As a result of this M.C.. it was discovered that a plugged Orifice in the pneu=atic controller of the valve was the source cf trouble.

The orifice vac repaired and the valve was i==ediately returned to service.

3cth incperable cc=ponents, VA-33 (breaker) and HCV h033 (pneunatic controller) were repaired and returned *.o operability within 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> which is within the 2h hour require =ent described by Technical Specification 2.a(2).

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Ctaha Public Power District Fort Calhoun Station Unit :To. 1 Oceket :To. 05000265 LZ?.30-001 Attachment Ifo. 3 Failure Data

~'his is the first failure of this type at the Fort Calhoun Station Unit :To. 1.

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