ML20214K518

Proposed Tech Spec,Adding Formula for Calculating Statistical Scram Speed Limit to Bases Section

ML20214K518
Person / Time
Site:	Hatch
Issue date:	05/18/1987
From:	GEORGIA POWER CO.
To:
Shared Package
ML20214K499	List: ML20214K496 ML20214K518
References
TAC-64779, TAC-64780, NUDOCS 8705280469
Download: ML20214K518 (1)

Text

-_

g . D

. BASES FOR LIMITING CONDITIONS FOR OPERATION AND SURVEILLANCE REQUIREMENTS 3.11.C. Minimum Critical Power Ratio (MCPR) (Continued)

According to Figure 3.11.4 or 3.11.5, the 100% power,100% flow operating limit MCPR (OLMCPR) depends on the average scram time, t, of the control rods, where: '

t = 0 or

• ave *B, whichever is gr' eater t -t g B where: tA = 1.096 sec (Specification 3.3.C.2.a. scram time limit to notch 36)

I/2 TB = y + 1.65 Ni a (Reference 10]

n I Ng i=1 where: y = 0.822 sec (mean scram time used in the transient analy' sis) o = .018 sec (standard deviation of y) n I Njtj tave = 1"1 n

I Ng i=1 where: n = number of surveillance tests performed to date in the cycle Ng = number of active control rods measured in the ith surveillance test tj = average scram time to notch 36 of all rods in the ith surveillance test N1 = total number of active rods measured in 4.3.C.2.a The purpose of the MCPR f , and thep K of Figures 3.11-3 and 3.11-6, respectively, is to define operating limits at other than rated core flow and power conditions. At less than 100% of rated flow and power, the required MCPR is the larger value of the MCPRy and MCPRp at the existing core flow and power state. The MCPRf s are established to protect the core from inadvertent core flow increases such that the 99.9% MCPR limit requirement can be assured.

The MCPR f s were calculated such that for the maximum core flow rate and the corres-ponding THERMAL POWER along the 105% of rated steam flow control line, the limiting bundle's relative power was adjusted until the MCPR was slightly above the Safety Limit. Using this relative bundle power, the MCPRs were calculated at different points along the 105% of rated steam flow control line corresponding to different core flows. The calculated MCPR at a given point of core flow is defined as MCPRf .

The core power dependent MCPR operating limit MCPRo is the power rated flow MCPR operating limit multiplied by the Kp factor given in Figure 3.11-6.

The Kp s are established to protect the core from transients other than core flow increases, including the localized event such as rod withdrawal error. The Kps were determined based upon the most limiting transient at the given core power level. (For further information on MCPR operating limits for of f-rated conditions, reference NEDC-30474-P.(11))

8705280469 DR 870518 ADOCK 05000321 3.11-4a Proposed TS/0120q/128 PDR .

- .