ML20065S806

Advises That Diverse Scram Sys Logic Circuit Simplified.New Design Reduces Number of Procedural Steps Required by Operator to Reset Protective Actuation

ML20065S806
Person / Time
Site:	Three Mile Island
Issue date:	12/19/1990
From:	Hukill H GENERAL PUBLIC UTILITIES CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
C311-90-2146, TAC-59151, NUDOCS 9012260075
Download: ML20065S806 (4)

Text

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GPU Nuclear Corporation u Nuclear  :=s:r8o Middletown, Pennsylvania 17057 0191 717 944 76?1 TELEX 84 2380 Writer's Direct Dial Number:

December 19, 1990 C311-90-2146 (TAC 59151)

U.S. Nuclear Regulatory Cctstission Attn Document Control Desk Washi.rgton, D.C. 20555 Gentlemon:

Subject:

Throo Mile Islard Nuclear Plant, Unit 1 (IMI-1)

Orcrating Licenso DPR-50 Docket No. 50-289 A1WS Design Implementation Simplification of Protectivo Action In the GPU Nuclear (GPUN) Ictter (C311-89-2058) dated October 4, 1989 GPUN described the Diverra Scram System (DSS) design relativo to completion of Protective Action at pago 11 and depicted on Figure 1. (Figure 1 is enclosed for caso of referenoo)

GPUN has ncw simplified the DSS logic circuit as depicted on Figure 1A also enclosed with this letter. Inck-up/ Scal-in of the DSS trip function is ncu achieved by the action of circuit breakers 1G-2A ard 11r2A, which lock-in/soal-in inherently, by design. Roset is dono locally by the operator at the breakers.

This simplified design achieves a reduction in the numter of procedural steps rcquired by an operator to reset a protective actuation. In the original design of Figure 1 the three stop proceduro consisted of: (1) Roset tho actuation; (2) recloco the breaker to energize the control Rod Drive System (CRDS); ard, (3) withdraw control rcds usirq the CRDS. The revised design is more typical of GWN procedures to reset a protectivo action. The two step procedure is: (1) reclose the breaker; and, (2) withdraw control rods using the CRDS. The acklitional step built in to the original design is unremry and results in added circuit acruplexity.

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This revir.cd design inplementation for Cttpletion of Protectivo Action has bocn dico meM with the Staff. The puTose of this letter is to doctment the subject design ctwyo, sinocroly, c

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