ML18227B786

Letter Transmitting Procedure for Evaluation of Maximum Setpoint Overshoot Heat Input Transient & Supplement to July 1977 Report of Pressure Mitigating Systems, Transient Analysis Results

ML18227B786
Person / Time
Site:	Turkey Point
Issue date:	01/03/1978
From:	Robert E. Uhrig Florida Power & Light Co
To:	Lear G Office of Nuclear Reactor Regulation
References
L-78-4
Download: ML18227B786 (8)

Text

NRC FSRM 195 I2 76)

U.S. NUCLEAR REGULATORY COMML DO UMBE E NUMBER ari NRC DISTRIBUTION FDR PART 50 DOCKET MATERIAL TO: FROM: DATE OF DOCUMENT Florida Power & Light Company 1/3/78 Mr. George Lear Miami, Florida DATE RECEIVED Robert Ei" Uhrig 1/11/78 ABETTER QNOTORIZEO PROP INPUT FORM NUMBER OF COPIES RECEIVED ORIGINAL UNCLASSIFIED OCOr Y 4/6w DESCRIPTION ENCLOSU RE Atto 1) Procedure for Evaluation of Maximum Setpoint Overshoot Heat Input Transients>>

Att 2) Supplement to the July 1977 Report-Pressure Mitigating Systems, Transient Analysis Results-REACTOR VESSEL OVERPRESSURIZATION DISTRIBUTION PER G, 'SECH '10 21 76 (1-P) (2-P )+(1/4" )

PLANT NAME: Turkey Point Units 3 & 4 o~p~<gp Rim6An guD/C4 1/11/78 RJL FOR ACTION/INFORMATION Ac drift tRd(EVE ~M SAFETY BRANCH CHIEF:

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Division of Operating Reactors Nuclear Regulatory Commission gff I(' Y~

Washington, D.C. 20555

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Dear Mr. Lear:

Re: Turkey Point Units 3 6 4 Docket Nos. 50-250 and 50-251 Over ressure Protection In our October 18, 1977 (L-77-324) submittal on the Overpressure Mitigating System (OMS) for Turkey Point, setpoint selection for the pressurizer power operated relief valves (PORV's) was based upon a July 1977 Westinghouse analysis. The maximum setpoint overshoot for heat input transients was evaluated with a PORV setpoint of 500 psig, the only setpoint considered in the Westinghouse July analysis. A supplement to the July report has been prepared which permits us to evaluate the maximum setpoint overshoot with a PORV setpoint of 415 psig, the setpoint selected for Turkey Point for reactor coolant temperatures below 300 F. The supplement is attached.

The chosen PORV setpoint of 415 psig is 85 psi below the minimum NDT pressure of 500 psig. The maximum,setpoint overshoot for heat input transients evaluated with a PORV setpoint of 415 psig increased from 14 psi at 100 F to 57 psi at 250 F. This is less than the margin to the minimum NDT pressure provided by the selected setpoint and confirms that the setpoint is conserva-tive for heat input, transients. The procedure for evaluating the setpoint overshoot is attached.

Very t ly yours, Robert E. Uhrig Vice President REU/MAS/lah Attachments (2) cc: James P. O'Reilly, Region II 780% f0142 Robert Lowenstein, Esquire PEOPLE.... SERVING PEOPLE

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PROCEDURE FOR EVALUATION OF MAXIMUM SETPOINT OVERSHOOT HEAT INPUT TRANSIENTS Turkey Point Units 3 and 4 parameters RCS Volume 9343 ft. 3 2(FSAR Table 4.1-1)

S.G. Area 44,430 ft. (FSAR Table 4.1-4)

PORV opening time 2.0 sec. (Pre-op test 1000.16)

Selected PORV setpoint 415 psig (below 300 F RCS temp.)

Figure and example numbers refer to the September 1977 supplement to the July 1977 report provided by Westinghouse.

(1) Evaluate the effect of S.G. UA on pressure overshoot (hP)

(Figures 14 thru 20).

Turke Point S.G. Area = 44,430 ft. 2 = .766 Reference S.G. Area 58,000 ft.

Turkey Point UA = .766 Reference UA Relief valve setpoint 400 psig, 3 second opening time:

Figure 14 Figure 15 Vol. 6000 ft. Vol. 13000 ft.

100oF hP = 25 psi hP = 16 psi 180oF hP = 59 psi hP = 51 psi 250oF hP = 93 psi hP =I72 psi Relief valve setpoint 500 psig, 3 second opening time:

Figure 16 Figure 17 Vol. 6000 ft. Vol. 13000 ft.

100 F hP = 23 psi hP = 21 psi 180oF hP = 74 psi hP = 53 psi 250 F hP = 109 psi hP = 91 psi (2) Evaluate the effect of RCS volume on pressure overshoot.

By linear interpolation of results from (1) above (as in supplement example 4);

RCS volume 9343 ft.3; 3 second opening time:

~Tem Set oint 400 si Set oint 500 si 100oF hP = 21 psi hP = 22 psi 180oF hP = 55 psi hP = 64 psi 250oF hP = 83 psi hP = 100 psi

0 ~g (3) Evaluate the effect of relief valve setpoint on pressure overshoot.

By linear interpolation of results from (2) above; Relief valve setpoint 415 psig; RCS volume 9343 ft. 3 three second opening time:

~Tem Pressure Overshoot 100oF bP = 21 psi 180 F hP = 57 psi 250oF hP = 86 psi (4) Evaluate the effect of valve opening time on pressure over-shoot.

Figures 1 6 show pressure overshoot directly proportional to valve opening time.

Therefore, applying all Turkey Point parameters:

~Tem Pressure Overshoot 100oF hP = 14 psi 180oF bP = 38 psi 250oF hP = 57 psi

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