ML20199K376

Submits Info to Assure Compliance W/Ts 3.2.b Which Requires That Total Scram Withdrawal Time for Both Safety Rods & Coarse Control Rod Be Less than One Second

ML20199K376
Person / Time
Site:	University of New Mexico
Issue date:	11/25/1997
From:	Busch R NEW MEXICO, UNIV. OF, ALBUQUERQUE, NM
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9712010097
Download: ML20199K376 (1)

Text

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hl sq The Ur'ivmit of New Mesico Chemical & Nudear I ngineering t u uery ,

7131 1 41 November 25,1997 Telephone (50$) 277-5431 FAX (505) 277-5433 U.S. Nuc! car Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555 The University of New Mexico Docket: 50-252 Albuquerque. New Mexico License: R - 102 To assure compliance with the technical specifications 3.2.b which require that the total scram withdrawal time for both safety rods and the coarse control rod be less than one second, we have done the following:

An infrared emitter / receiver circuit was setup and connected to a digital data acquisition board mounted in a computer. The circuit consists of an infrared emitter with a compensating resistor sending a beam of infrared light to an infrared receiver and ccmpenscting resistor. The two components are placed on the bottom plate of the ccatrol rod with the beam transmitted and received.

When the control rod drops out of the core and reaches its out position, the beam is interrupted creating a change in the condition of the digital input. Another of the digital input ports was connected to the manual scram button on the re.ctor console. These two inputs were used to measure the total time from initiation of scram tc rod full out position. When the manual scram button is pushed, the computer timing circuit is initiated. The timer remains in operation until a signal is received from the infrared circuit indicating that the rod is in its out position. The change in the digitalinput resulting from the interruption of the infrared beam terminates the timing operation and prints the total scram time to the computer screen. Measurements on the two safety rods and the coarse control rod indicate the following scram times: Safety Rod 1 : 330 +/- 2 milliseconds, Safety Rod 2 : 274 +/- 4 milliseconds, and Coarse Control Rod : ;64 +/- 4 milliseconds. The variations in scram times among the 3 rods are attributed to the differences in spring tension in each rod. Based on these measurements, UNM is in compliance with this part 3.2.b of the technical specifications.

This procedure will be <epeated annually as part of the annual maintenance to ensure continued compliance.

Sincerely, eukL1 Robert D. Busch, Ph.D, P.E.

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Chief Reactor Supervisor cc: Tom Burdick, inspector, US NRC, Region 111 9712010097 971125 i,o" ^oockosoiaa d gtytp{ttplJ4g .