ML20113D568

RO 85-2;on 850111,safety Channel 1 Detector Failed During Reactor Operation.Caused by Loose Connector Pin Making Intermittent Contact.New Connector Installed & Detector Verified Operable Prior to Reinstallation

ML20113D568
Person / Time
Site:	05000128
Issue date:	01/21/1985
From:	Rogers D TEXAS A&M UNIV., COLLEGE STATION, TX
To:	Johnson E NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
References
REF-PT21-85-216-000 PT21-85-216, PT21-85-216-000, RO-85-2, NUDOCS 8504150372
Download: ML20113D568 (2)

Text

.

o 'bma c

TEXAS ENGINEERING EXPERIMENT STATION THE TEXAS A&M UNIVERSITY SYSTEM COLLEGE STATION, TEXAS 77843-3575

]#

~

21 January 1985 NUCLEAR SCIENCE CENTER 409/845-7551 Mr. E. Johnson Office of Inspection and Enforcement Region IV U.S. Nuclear Regulatory Commission 611 Ryan Plaza Drive, Suite 1000 Arlington, Texas 76012

Dear Mr. Johnson:

I am forwarding the final report of the reportable occurrence of 11 January 1985. This report is being submitted in accordance with NSC Technical Specifi-cation Section 6.6.2 for License R-83, Texas A&M University.

Respectfully, dh Q#"

Dale Rogers Assistant Director DR/ym Enclosure 8504150372 850121 PDR ADOCK 05000128 S PDR RESEARCH AND DEVELOPMENT FOR MANKIND go

.o W

Reportable Occurrence #85-2 Failure of Reactor Safety System Channel (Safety Measuring Channel)

During Reactor Operation REPORTABLE OCCURRENCE On 11 January 1985 at 0943 the reactor was started up following the performance of annual reactor maintenance. In preparation for the pool calorimetric the reactor was taken to 400 Kw as indicated on the linear channel.

However Safety Channel #2 indicated 42%, while Safety Channel #1 indicated 5%. At first it was felt that the Safety Channel #1 detector had been positioned incorrectly following detector maintenance. However, adjusting the detector caused no change in the meter response. The reactor was shutdown at 1014, and '

electronics personnel began their investigation.

CORRECTIVE ACTION It was initially felt that detector cabling for Safety Channel #1 and the pulse chamber had been swapped during maintenance; however, this could not be verified. The investigation by electronics personnel included cabling checks and test current inputs at the instrument and at cable connectors. Once all connectors were restored to normal the reactor was started up a second time at 1203. However, the Safety Channel #1 again did not respond. The reactor was again shutdown and the pulse channel detector and cabling was swapped with Safety Channel #1. The subsequent startup at 1341 was performed with no further problems. It has, therefore, been concluded that the Safety Channel #1 detector failed during reactor operation. Further tests indicate that the connector pin on the detector was loose and making intermittent contact. A new connector will be installed, and the detector will be verified operable prior to being reinstalled.

<3

_ _ - _ _ _ _ _ _ . . _ _ _