ML19326A130

Safety Evaluation Supporting Change to Relevant Tables & Figures Re Actual Reactor Pump Coastdown Characteristics

ML19326A130
Person / Time
Site:	Davis Besse
Issue date:	10/23/1978
From:	TOLEDO EDISON CO.
To:
Shared Package
ML19326A128	List: ML19326A127 ML19326A130
References
NUDOCS 8002030010
Download: ML19326A130 (1)

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DB-1 SAFETY EVALUATION The as-measured one pump coastdown curva determined for the Davis-Besse Nuclear Fower Station Unit No.1 Reactor Coolant Pumps is more restrie-tive than the design coastdown curve which was used in the original safety analyses. For Fuel Cycle 1 prior to the removal of orfice rod assemblies (ORA) it was not necessary to change the nuclear parameter limits because the effect of the actual coastdown curve was more than offset by the excess reactor coolant flow. For Cycle 1 af ter the removal of ORA, 5% of the 8% excess flow is being used to compensate for the lower flow through the core. A new analysis has been therefore been performed using a more restrictive pump coastdown curve. This new

analysis results in the changes to the Reactor Core Safety Limit Curve (Figure 2.1-1 of the Technical Specifications), the Reactor Ptotection System Instrumentation Trip Setpoints (Table 2.2-1 and Figures 2.2-1 and 2.2-2) and associated bases. Also, the maximum Reactor Coolant Eat Leg Temperature was reduced for DN3 Margin (Table 3.2-1). These new Techni-cal Specifications, determined by performing the appropriate Safety

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Analysis using the more restrictive pump coastdown curve, are mora conservative than the previous specifications and do not present any unreviewed safety questions.

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