ML20151G661

Special Rept:On 880315,alarms Received in Control Room Which Indicate Problems W/Qualified SPDS Channel a (QSPDS A). Personnel Noticed Smell of Hot Insulation Coming from QSPDS a Panel AI-208A.Caused by Overheated Expander Card

ML20151G661
Person / Time
Site:	Fort Calhoun
Issue date:	04/14/1988
From:	Andrews R OMAHA PUBLIC POWER DISTRICT
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
LIC-88-219, NUDOCS 8804200093
Download: ML20151G661 (4)

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Omaha Public Power District 1623 Harney Omaha. Nebraska 68102 2247 402/536 4000 l

l April 14, 1988 I LIC-88-219 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555

Reference:

Docket No. 50-285

SUBJECT:

Special Report on Inoperability of Post-Accident Monitoring Instrumentation Gentlemen:

The Omaha Public Power District, holder of Operating License DPR-40, submits this special report pursuant to the requirements of Fort Calhoun Station Unit No.1 Technical Specification 2.21, "Post-Accident Monitoring Instrunientation."

Fort Calhoun Station Unit No.1 Technical Specification 2.21 Table 2-10 Item 8, specifies the requirements for the core exit thermocouples (CETs). Action (i) requires with the number of Operable Core Exit Thermocouples less than the four required by NUREG-0737, either restore the number of operable channels to at least four within seven (7) days of discovery of the inoperability, or prepare and submit a special report to the Nuclear Regulatory Commission. This report is being submitted because for more than seven days core quadrant I had only three operable CETs.

On March 15,1988 at 0401, alarms were received in the Control Room indicating problems with the Qualified Safety Parameter Display System Channel A (QSPDS A). The situation was assessed and QSPDS A was declared inoperable. At 0417 Operations personnel noticed the smell of hot insulation emanating from within the QSPDS A panel AI-208A and immediately de-energized the panel. De-energiz-ing the panel resulted in halting the source of the fumes.

Maintenance Order #881100 was issued to investigate the problem. It was discovered that the Isolated Expander Module on the DT-1748-1 Expander Card had been overheated resulting in the failure of the QSPDS A panel. The DT-1748-1 Expander Card collects and relays the inputs from 8 Core Exit Thermocouples and the inputs from 4 Heated Junction Thermocouples (2 heated and 2 unheated) to the QSPDS A central processing unit. The damaged card was replaced and function testing initiated, j 8804200093 880414 PDR ADOCK 05000285 S DCD j'2 as sa r ~~ggow-.% /j

U. S. Nuclear Regulatory Commission LIC-88-219 Page 2 The number of core exit thermocouples per quadrant for each channel is shown in Figure 1. Figure 2 indicates the number of CETs affected and the number of CETs operable. Only quadrant I had less than four operable CETs as a result of the card failure. Table 1 indicates that the number of Heated Junction Therm-ocouples (HJTCs) was within Technical Specification requirements during the equipment failure.

During the trouble shooting on March 23, 1988, the ISBC-544 Communications Controller Board was found to be inoperable. The ISBC-544 Communications Con-troller Board interfaces the central processing unit with the screen in the QSPDS A panel and with the Emergency Response Facility Computer System as part of the Safety Parameter Display System (SPDS). The defective board was sub-sequently replaced. After replacement of the DT-1748-1 card, the QSPDS A panel was calibrated using procedure CP-A/QSPDS. Surveillance tests ST-SCMM-1 F.1 and ST-HJTC-1 F.1 were satisfactorily performed following the replacement of the ISBC-544 Communications Controller Board. The equipment was returned to service and declared operable on March 23, 1988 at 1705.

Subsequently it was discovered that some seismic bracing had not been rein-stalled in the panel since the March 23 repair. Therefore, at 1530 hours0.0177 days <br />0.425 hours <br />0.00253 weeks <br />5.82165e-4 months <br /> on April 6, 1988 QSPDS A was again declared inoperable. The required repairs were completed zt 1117 hours0.0129 days <br />0.31 hours <br />0.00185 weeks <br />4.250185e-4 months <br /> on April 9, 1988. Corrective actions have been comple-ted. This special report is being issued within the 30 day limit as specified in Technical Specification 2.21 Table 2-10, Item 8 (1).

Sincerely, dl k hidL &

R. L. Andrews Division Manger

Nuclear Production RLA/me c

LeBoeuf, Lamb, Leiby &MacRae 1333 New Hampshire Ave. N.W.

Washington, DC 20036 R. D. Martin, NRC Regional Administrator i

P. H. Harrell, NRC Senior Resident Inspector A. Bournia, NRC Project Manager i

I

9 Nunter of Core Exit Thermocouples instelled in QSDOS Chennele A & B CETs CErs CETs CETs 4edrent1 bedrent 2 Wedrent1 Wadrant2 4 3 3 4 3 4 4 3 I

.- Wedrent 4 4edrent 3 Quadrant 4 Cusarent 3 s CETs CETs CEra CErn l

l QSPDS Channel A QSPOS Channel B Noreg-0737 Item ilf.2 recutres each core quadrant to be monitored by 4 Core Exit Thermocouples if this con not be me;ntained restore to et leset four per core quadrant within 7 days or witt,In 3C days of the disewery of inoperabilfly submit a report to the Nuclese Regulatory Commission.

Fort Caihoun Techalesl Specification 2.21 requires et least 2 Core Exit Thermocouples per core quadrant or restore to e least 2 per core guvdrent within 7 days or be in hot shutdown within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />,if no Core Exit Thermocouples are opersale in a core quadrant either restore the Inoperable channel (s) within 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> cc os in het shutdown within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.

Figure 1 Number of Core Exit Thermocouples Affected in QSPOS Channels A & B by Damaged QSPDS Card t

CETs CETs CETs CETs

%edrent t hedrent 2 Nedrent1 Wadrant 2 4 (0) 2 (1)! 0 (3) 0 (4h 0(3) 2 (2) 0(4) 0 (3)

Quadrant 4 Wadrant 3 QJadrant 4 Quadrant 3 CETs CETs CETs CErs QSPD0 Channel A OSPDS Channel B j

Numbers represent the number of effected Core Exit Thermocouples in each Quadrent, Number 4 in parenthests represent coerable Core Exit Thermocouples Figure 2 l

l l

2

l 1

Affected Hosted Junction Thermocouples by OSPOS Channel A fnoperebility l l

HEATED HJTC AFFECTED UhHEATED KJTC AFFECTED THIA NO TU1A NO TH2A NO TV2A NO TH3A N0* TV3A N0a TH4A NO TV4A NO THSA NO TU5A N0 TH6A NO TU6A NO TH7A YES TU7A YES TH8A YES TVBA YES

'PREVIOUSLY IN0PERABLE Hested Juncuon Thermocouples coersta se a celr (one hoeted and one unhested compelse a funcuonal Heeled Junction Thermocouple). Heeled Junctica inermocouples 1-4 comprise the Upper string and Heated Junction Thermocouples 5-6 ce~pelse the Lower String.

Technical Speelflection 2.21 dertnes so operable string as having four functional Heated Juncuon Thermocovotes with at least 2 each in the Upper and Lower $trings.

Table 1

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