ML20155B267

Forwards Lists of Assumptions Used,Feedwater Line Break Sequence of Events & Plots of RCS & Pressurizer Pressures, Pressurizer two-phase Level & Reactor Vessel Upper Head Subcooling Per TMI Action Item II.D.1

ML20155B267
Person / Time
Site:	Calvert Cliffs
Issue date:	05/25/1988
From:	Tiernan J BALTIMORE GAS & ELECTRIC CO.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
TASK-2.D.1, TASK-TM NUDOCS 8806130128
Download: ML20155B267 (13)

Text

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B ALTIMORE ,

CAS AND l ELECTRIC CHARLES CENTER 'R O. BOX 1475 BALTIMORE. MARYLAND 21203 JostPH A.TIERNAN Vict PatstotNT NWCLEAR ENEROY May 25,1988 i

U. S. Nuclear Regulatory Commission Washington, DC 20555 ATTENTION: Document Control Desk

SUBJECT:

Calvert Cliffs Nuclear Power Plant Unit Nos.1 & 2; Decket Nos. 50-317 & 50-318 TMl Action Item II.D.1, Performance Testing of Relief and Safety  ;

Valves

REFERENCES:

(a) Letter from Mr. J. A. Tiernan to NRC Document Control Desk, dated  :

January 6,1988, same subject [

s i (b) Letter from Mr. S. A. McNeil to Mr. J. A. Tiernan, dated l April 30,1987 Request for Additional Information Gentlemen:

il In Reference (a), we answered 16 of the 18 questions you had regarding our implementa-tion of TMI Action item II.D.I.

One of the two remaining questions addresses the ability of the motor operators to provide adequate torque to close the PORY block valves (Question 2, Reference b). We are now testing those valves during the Unit I refueling outage. We will provide the results to you shortly after completion. L

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, The second question asks us to demonstrate that PORVs and safety valves will function .

properly during a feedwater line break. The feedwater line break was analyzed to l j determine the resultant increase in pressurizer level. The analysis was performed l using the CENTS ccde. The code has been benchmarked and a topical report has been l submitted to the NRC staff.

I The analysis demonstrates the RCS pressure remains below 2750 psia, the two-phase

! pressurizer level remains far below the safety valve inlet nozzles, and reactor vessel i l upper head subcooling is maintained.  !

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8806130128 880525 k h PDR ADOCK 05000317 i P DCD

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Document Control Desk ,

May 25,1988-Page 2 Attachment (1) lists the assumptions used, Attachment (2) shows the sequence of events for the limiting feedwater line break, and Attachment (3) provides pints of the RCS and pressurizer pressures, pressurizer two-phase level, and reactor vessel upper head subcooling.

Should you have any further questions regarding this matter, we will be pleased to dheuss them with you.

Very truly yours,

, s.

f bN JAT/ WPM /dlm Attachments cc: D. A. Brune, Esquire

J. E. Silberg, Esquire R. A.Capra, NRC S. A.McNeil, NRC

W. T. Russell, NRC i D. C.Trimble, NRC a

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_ ________ ______ ___ _ _____________________ _ j

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Attachment 1

- Page 1 of 5 Calvert Cliffs 1 and 2 Feedline Break Analysis Assumptions 1.0 Break .

1.1 Location The break is assumed to occur between the steam generator and the last check valve, resulting in a non-isolable break.

1.2 Fize AspecNrumofbreaksuptoandincludingadouble-endedguillotine were evaluated. The double-ended guillotine was found to be -

limiting because smaller breaks will trip on low level in the intact steam generator before high pressurizer pressure trip occurred.

1.3 Discharge n .

For conservatism, the feed line is assumed to be at the elevation of the tube sheet. Thus, saturated liquid discharge occurs until the l steam generator is nearly dry.

l 1.4 Main Feedwater l

l Main feedwater flow is terminated instantaneously at the time of the

. break.

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i Page 2 of 5 2.0 Pressurizer 2.1 Flashing The water in the pressurizer flashes when precsurizer pressure falls below saturation.

2.2 Pressurizer Safety Valves See Table 1.

2.3 Safety Valve Inlet The safety valve inlet is 0.35 feet above the upper level tap.

3.0 Initial Conditions See Table 2.

4.0 Offsite Power Offsite power is lost 3 seconds after turbine trip on reactor trip.

5.0 Non-Safety Grade Eauioment Only safety grade equipment is assumed to mitigate the transient. Non-safety grade equipment, including the PORVs and steam bypass controls, are assumed unavailable.

ss Page 3 of 5 6.0 Reactor Trio The low level trip in the affected SG (the one with the breakfwill be neglected. Thus, the reactor will trip on high pressurizer pressure or low level in the unaffected SG.

7.0 Operator Action No operator action is credited.

8.0 RPS/ESFAS RPS and ESFAS setpoints and response times are taken from the Technical Specifications.

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Page 4 of 5 Table 1 Pressurizer Safety Valve Parameters 6

Design Pressure, psia ,

2,500 Design Temperature F 700 Fluid Saturated Steam, 0.1% (wt) Boric Acid Set Pressure:

RC-200, psig 2485 + 1% uncertainty RC-201, psig 2550 + 1% uncertainty Capacity, at set pressure:

RC-200, lbm/hr 296,065 RC-201, ibm /hr 303,765 Blowdown:

RC-200, psig 1985*

RC-201, psig 2037*

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l. *These blowdown pressures correspond to a 20% blowdown which bounds the blowdowns resulting from the recommended ring settings in the "Calvert

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l Cliffs Nuclear Power Plant Units 1 and 2, Pressurizer Safety Valve l Operability Report", CEN-248(B), May 1983 l

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o Page 5 of 5 Table 2 ,

In,itial Conditions

-Core Power 2757 MW RCP Heat 10 MW RCS Pressure 2343 psia Pressurizer Pressure 2298 psia SG Pressure 884 psia Feedwater Temperature 440 F Feedwater Pressure 907 psia Core Flow 38,674 lbm/sec.

- Core Inlet Temp 549 F

~4 MTC +0.5 x 10 JV'/ F SG Level Above Tube Sheet 35.3 ft Pressurizer Level 70.3%

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Attachment 2 P. age 1 of 2 CALVERT CLIFF 1 AND 2 FEE 0 WATER LINE BR$AK,

, SEQUENCE OF EVENTS' TIME EVENT VAL'UE 0.0 Double-ended break in main feedwater 1.767 2

line of SG 1, ft .

Instantaneous loss of feedwater to both SGs' 17.0 Low level trip condition reached in 10.

SG 2, inches below top of feed ring 17.2 High pressurizer pressure trip 2400.

condition reached, psia

.8.2 Electrical power to CEA holding coi'is ---

is interupted Turbine-generator trips ---

18.6 SG 1 drys out ---

18.7 Control rods begin to fall into the ---

reactor 18.8 Pressurizer safety valve RC-200 opens, 2525.

psia 19.4 Pressurizer safety valve RC-201 opens, 2590.65 l psia 20.6 Maximum RCS pressure, psia 2655.3 l

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Page,2 of 2. c CALVERT CLIFF 1 AND 2 FEEDWATER LINE BREAK

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SEQUEN,'E OF EVENTS (CONTINUE 0)

TIME EVENT VALUE 21.2 Loss 'f o offsite power RCPs trip ---

Letdown valves close ---

29.6 Maximum two phase level in the 6.9 pressurizer, ft. below the PSVs' inlet nozzles 33.2 Pressurizer safety valve RC-201 closes, 2052.

psia 40.2 Pressurizer safety valve RC-200 closes, 2000, psia 0

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