ML19351D152
| ML19351D152 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 09/22/1980 |
| From: | Mills L TENNESSEE VALLEY AUTHORITY |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| IEB-80-18, NUDOCS 8010090094 | |
| Download: ML19351D152 (6) | |
Text
-,-
8 TENNESSEE VALLEY AUTHORITY,,,
& c:
CH ATTANOOGA. TENNESSEE 374o1 400 Chestnut Street Tower II September 2U 898p] A9 2l Mr. James P. O'Reilly, Director Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission Region II - Suite 3100 101 Marietta Street Atlanta, Georgia 30303
Dear Mr. O'Reilly:
OFFICE OF INSPE ION AND ENFORCEMENT BULLETIN 80 NRC-0IE REGION II LETTER RII:JP 0-327) SEQUOYAH NUCLEAR PLANT UNIT 1 - RESPCNSE TO BULLETIN Enclosed is our response to your letter dated July 24, 1980, which transmitted IE Bulletin 80-18 on Adequate Minimum Flow Through Centrifugal Charging Pumps. As indicated in the enclosure, we expect to submit the results of our analysis by October 17, 1980. In our next report, we will provide v-
. estimate of the number of manhours expended to comply with thi_
.,2n.
If you have any questions, please get in touch with D. L. Lambert at FTS 857-2581.
Very truly yours, TENNESSEE VALLEY AUTHORITY l
L. M. Mills, ager Nuclear Regulation and Safety Enclosure cc: Director, Division of Reactor Operations Inspection (Enclosure)
Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission Washington, DC 20555 gi.pk.IkkabN' 8010090 Oh Ah Equal Opportu ity Employer
ENCLOSURE SEQUOYAH NUCLEAR PLANT UNIT 1 RESPONSE TO IE BULLETIN 80-18 ADEQUATE MINIMUM FLOW TO CE!ERIFUGAL CHARGING PUMPS Response to Item 1 of the Bulletin TVA has completed _ calculations to determine if the Sequoyah Nuclear Plant unit 1 charging system would maintain adequate pump flow during parallel safety injection operation and determined that adequate flow would not be maintained. The detailed calculations outlined by the Westinghouse Electric Corporation letter (NS-TMA-2245) are attached.
Response to Item 2 of the Bulletin Modifications are planned for Sequoyah unit 1 as described under a.
Interim Modification I of the Westinghouse letter attached to the bulletin. These modifications include:
(1) Verifying that the CCP miniflow return is aligned directly to the CCP suction during normal operation with the alternate return path to the volume control tank isolated (locked closed).
(2) Removing the safety injection initiation automatic closure signal from the CCP miniflow isolation valves.
(3) Modifying plant emergency operating procedures to instruct the operator to:
(a) Close the CCP miniflow isolation valves when the actual RCS pressure drops to the calculated pressure for manual reactor coolant pump trip.
(b) Reopen the CCP miniflow isolation valves should the wide range RCS pressure subsequently rise to greater than 2,000 psig.
These modifications are expected to be complete by October 17, 1980.
In view of the startup test schedule, TVA does not believe this schedule for modifications has any significant safety implications.
b,c,d,e.
An analysis is presently being evaluated taking in to con-sideration these items. This analysis is expected to be submitted by October 17, 1980.
r ATTACHMENT SEQUOYAH NUCLEAR PLANT UNIT 1 MINLMUM CENTRIFUGAL CHARGING PUMP FLOW DURING IWO PUMP PARALLEL SAFETY INJECTION CALCULATION FOR NRC IE BULLETIN NO. 80-18 Purpose Check capability to provide minimum pump flow during parallel safety injection with two centrifugal charging pumps (CCP's).
References 1.
2.
Letter from T. M. Anderson, Westinghouse Water Reactor Division, to V. Stello, NRC, dated May 8,1980, No. NS-TMA-2245.
3.
Sequoyah Nuclear Plant Unit 1 Preoperational Test WG.lC data.
Calculations Following the format suggested in Reference 2, using data from Reference 3.
Step 1: Maximum developed head pump flow = 2,600 psid = 6,006 ft. @
73.1 gpm (pump 1A-1A)
Minimum developed head pump flow = 2,470 psid = 5,705.7 ft. @
72.3 gpm (pump 1B-1B)
Step 2:
Correction for testing error.
Test gauge accuracy =.25% x 3,000 psig = 7.5 psi (17.25 ft.)
+ 10 psi (23 ft.) reading accuracy = 40.25 ft.
Maximum pump = 6,046.25 ft. @ 73.1 gpm Minimum pump = 5,665.45 ft. @ 72.3 gpm Step 3:
From construction of pump flow curves, attached, minimum pump =
5,670 ft. @ 60 gpm Projection of weak pump head point on strong pump operating curve shows flow of 224 gpm.
Total flow from both CCP's guaranteeing 60 gpm to tie weak pump is 224 gpm + 60 gpm = 284 gpm Step 4: Determination of injection piping head loss.
- From Reference 3, runout head of pump 1A-1A = 480 psi runout flow of pump 1A-1A = 490 gpm e
e m
w,
-,-r
Developed Head Ajl 1104 ft.
-3 4.6 x 10 ftjgpm K = (Runout Flow Rate)2 Q'
(490 gpm)z
=
The resistance of the injection piping (Ahf) at the total CCP flow required to maintain 60 gpm through the weak pump is:
-3 Ahf = KQ2 = (4.6 x 10
_t/gpm) (284 gpm) = 370.86 ft.
Step 5:
RCS head loss for 4-loop plant - 50 psid (116 f t.)
Step 6:
Determining elevational head loss RWST elevation
~
739' - 5 3/4" CCP suction elevation 672' - 11" RCS cold leg injection nozzle elevation '
697' - 1 13/16" Pressurizer safety valve elevation 757' - 2 3/16" RWST to CCF suction 06.56' Minus CCP suction to RCS
-24 23' Minus RCS to pressurizer S.V.
(60.03 ft. assuming a full pressurizer)
(Corrected for density difference)
-43.30'
- 0.97' Step 7:
Calculation of pressurizer safety valve pressure Note: 1% setting tolerance Relief pressurizer = 2,485 psig + 25 psig = 2,510 psig (5,798 f t.)
l Step 8:
Determination of maximum RCS pressurizer pressure at which 60 gpm minimum flow is maintained to weak CCP.
Maximum RCS pressurizer = (CCP developed head @ total CCP flow) -
(injection piping head loss) - (Head loss through RCS) -
1 (elevation head loss)
Maximum RCS pressurizer = 5,665.45 - 370.86 - 116
.97 =
5,177 ft. = 2,241.5 psig Conclusions Comparing the maximum RCS pressurizer = 2,241.5 psig with the safety valve relief pressurizer = 2,510 psig, it is evident that the 60 gpm flow required for the weak CCP will not be maintained.
SRM:CLT 9/8/80
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