ML20216J789

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Provides Required 30-day Event Rept 99-19 for Event That Resulted from Failure of Cascade Automatic Data Processing Data Processing Smoke Detection Sys at Portsmouth Gaseous Diffusion Plant.Encl 2 Is List of Commitments Made in Rept
ML20216J789
Person / Time
Site: Portsmouth Gaseous Diffusion Plant
Issue date: 09/27/1999
From: Jonathan Brown
UNITED STATES ENRICHMENT CORP. (USEC)
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GDP-99-2054, NUDOCS 9910060159
Download: ML20216J789 (4)


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A Global Energy Company -

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' September 27,1999 GDP 99-2054 -

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U. S. Nuclear Regulatory Commission j

Attention: Document Control Desk

. Washington, D.C. 20555-0001 j

. Portsmouth Gaseous Diffusion Plant (PORTS)

Docket No. 70-7002 Event Report 99-19' 1

Pursuant to 10CFR76.120(d)(2), Enclosure 1 provides the required 30 day Event Report for an event that resulted from failure of the cascade automatic data processing smoke detection system at the Portsmouth Gaseous Diffusion Plant. Enclosure 2 is a list of commitments made in the report.-

Should you require additional information regarding this event, please contact Scott Scholl at (740) 897-2373.

- Sincerely, c

. Morris Brown General Manager Portsmouth Gaseous Diffusion Plant

Enclosures:

As Stated cc:

NRC Region III Office NRC Resident inspector-PORTS

-ass a,

9910060159 990927 PDR ADOCK 07007002 C

PDR United States Enrichment Corporation Portsmouth Gaseous Diffusion Plant P.O. Box 628, Piketon, OH 45661

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GDP 99-2054 Page1of2 Event Report 99-19 Description of E' vent At 1600 hours0.0185 days <br />0.444 hours <br />0.00265 weeks <br />6.088e-4 months <br /> on August 30,1999, an engineer reviewing the X-300A computer data logs determined that the Low Assay Withdrawal (LAW) station in the X-333 Process Building had operated in' Mode 2 through 4 for approximately nine hours with an inoperable cascade automatic data processing (CADP) system. :The Technical Safety Requirement (TSR) for the LAW station -

states that the CADP. smoke detection ' system shall be operable in Mode 2 (compression /

. liquefaction), Mode 3 (withdrawal), and Mode 4 (standby). The failure of the CADP safety system was reported in accordance with 10CFR76.120(c)(2).

A review of the event found that operators reported the CADP mimic panel lights for unit 33-8 and L

LAW were not lit at 2300 hours0.0266 days <br />0.639 hours <br />0.0038 weeks <br />8.7515e-4 months <br /> on August.27,1999.' No audible or visual alarms were received in the area control room (ACR 1) or the X-300 Plant Control Facility. Operators investigating the loss

. of mimic panel lights found that the unit processor at the local control center (LCC) appeared to be ramping the smokehead firing voltages properly and that cell temperature data was being transmitted to ACR 1. The operators interpreted these indications as a failure in the mimic panel which did not

' affect system operability or alann capability. At 2330 hours0.027 days <br />0.647 hours <br />0.00385 weeks <br />8.86565e-4 months <br />, the ACR 1 front line manager (FLM) l

reported the mimic panel problem to the Plant Shift Superintendent (PSS). The PSS declared the 33-8 mimic panel inoperable and concurred with the FLM's assessment that alarm capability would not be affected and that the smoke detection system could remain operable.

1 At 0700 hours0.0081 days <br />0.194 hours <br />0.00116 weeks <br />2.6635e-4 months <br /> on August 28,1999, the 33-8 unit processor software was reloaded in accordance with

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the procedural response for loss of mimic panel lights. The reload restored the lights on the mimic -

panel, but did not clear all system problems. At 1800 hours0.0208 days <br />0.5 hours <br />0.00298 weeks <br />6.849e-4 months <br />, maintenance troubleshooting discovered smokehead S88 in unit 33-8 was shorted out, disabling Datacom A. The DataCom units provide the data to the unit processors, so a failure or transient in the DataCom might adversely affect the

'_ unit processor. When smokehead S88 was disconnected, DataCom A operated properly. At 2129 hours0.0246 days <br />0.591 hours <br />0.00352 weeks <br />8.100845e-4 months <br /> following repairs, DataCom A and the unit 33-8 mimic panel were declared operable.

o On August 30,1999, the CADP system engineer investigated the system response which caused the 3

i mimic panel to become inoperable. To determine if data had been transmitted properly from the unit L

processors in X-333 to the X-300A central computer and on to the' alarm typer in ACR 1, the

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-X-300A central computer data logs were reviewed. The engineer found temperature data, but no unit L

33-8 smokehead data from 2200 hours0.0255 days <br />0.611 hours <br />0.00364 weeks <br />8.371e-4 months <br /> on August 27,1999, to 0700 hours0.0081 days <br />0.194 hours <br />0.00116 weeks <br />2.6635e-4 months <br /> on August 28,1999.

The engineer determined that even though the unit 33-8 smokeheads appeared to have been ramping

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properly, that' data was not being transmitted between the 33-8 unit processor and the X-300A central computer. As a result, alarm signals could'.not be sent to the alarm typer. With the mimic panel i

l inoperable, an alarm condition from a unit 33-8 smokehead would not have been annunciated.

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t GDP 99-2054 Page 2 of 2

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l Event Report 99-19 c

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. Cause of Event The direct cause of the CADP failure was a 'short in smokehead S88, in unit 33-8, which disabled DataCom A.' An electrical transient from the shorted smokehead or the inoperable DataCom A affected the ability of the system to conununicate alarms by disabling the link between the central

computer and the 33-8 unit processor. The smokehead ramping function continued to operate, but smokehead data was not transmitted to the X-300A central computer. Without the data input, no

' alann signals could be transmitted to the alarm typer in the ACR. When the unit processor software was reloaded and the computer links were re-established, all unit processor functions returned to normal and data transmission resumed.

j The root cause of the event was a failure to follow procedures. The procedure for operating the

. CADP system directs the operator to place the affected units in a manual mode of operation if the

. mimic panel is n'ot operational.' Personnel troubleshooting the condition of the mimic panel did not consult the CADP operations ~ procedure for direction and the PSS did not question what the

.~ procedural requirements were.. By following the procedure, the CADP would have been placed in manual mode which would have allowed continued monitoring. Disciplinary action was issued to responsible personnel.

. Corrective Actions

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By. October 22,1999, Opt, rations'will complete a Lessons Learned on this event and the importance of following procedures.

Extent of Exposure ofIndividuals to Radiation or Radioactive Materials

' There were no exposures to radiation or radioactive materials due to this event.

Lessons Learned -

. Personnel must be knowledgeable of procedural requirements for actions which should be taken

. during equipment failures. The PSS should reinforce this practice by inquiring whether all

. applicable procedural steps have been taken before making operability decisions.

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GDP 99-2054 4

Page1of1 Event Report 99-19 l

List of Commitments I

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By October 22,1999, Operations will complete a Lessons Learned on this event and the importance of following procedures.

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' Regulatory commitments contained in this document are listed here. Other corrective actions listed in this submittal are not considered regulatory commitments in that they are either statements of actions completed, or they are considered enhancements to USEC's investigation, procedures, programs, or operations.

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