ML20080B097
| ML20080B097 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 02/02/1984 |
| From: | Dixon O SOUTH CAROLINA ELECTRIC & GAS CO. |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8402060470 | |
| Download: ML20080B097 (4) | |
Text
{{#Wiki_filter:O SOUTH CAROLINA ELECTRIC 8c GAS COMPANY PGST OFFICE 764 CotuusiA south CAROUNA 29218
- o. W. DIXON, JR.
v,Ca p...orav February 2, 1984 NUCLEa OrgaatioNS Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C. 20555
Subject:
Virgil C. Summer Nuclear Station Docket No. 50/395 Operating License No. NPF-12 Cold Overpressure Protection System (COPS)
Dear Mr. Denton:
South Carolina Electric and Gas Company (SCE&G), in letters dated June 29, 1983, August 24, 1983 and October 21, 1983 (Mr. O. W. Dixon, Jr. to Mr. H. R. Denton), provided a design description of a Cold Overpressure Protection System (COPS) utilizing the Residual Heat Removal System (RHRS) relief valves for Staff review. A meeting was conducted on January 11, 1984 between the NRC Staff and SCE&G to discuss the details of our proposed COPS design. During this meeting the Staff expressed concern about our proposed use of power lockouts, augmented by administra-tive procedures, to mitigate the consequences of a single failure of a pressure transmitter which provides a signal fcr the automatic closure interlock of RHRS suction isolation valves. As a result, SCE&G has reevaluated its design and has decided to make a change to circumvent the single failure problem and use of power lockouts during COPS operation. This change also obviates the necessity of power lockouts as discussed in our response to FSAR Question 211.25. As shown on Attachment I, the new proposed design requires the revision of the automatic closure interlocks (not the open permissive interlocks) such that valves XVG-8701A and XVG-8702A are closed by Pressure Transmitter PT-403, and valves XVG-8701B and XVG-8702B are closed by Pressure Transmitter PT-402. Electrical isolation will be required to interface an A-Train (B-Train) interlock to a B-Train (A-Train) motor operated valve. A single alarm will also be provided to alert the operator if the Reactor 8402060470 840202 PDR ADOCK 05000395 lsl i. P PDR
Mr. Harold R. Denton Cold Overpressure Protection System (COPS) February 2, 1984 Page #2 Coolant System (RCS) temperature is less than 300*F and any of the RHR suction isolation valves are not full open. This preliminary design change has been evaluated under 10CFR50.59 and does not represent an Unreviewed Safety Question. As the detailed design and design verification are completed, any necessary changes will be evaluated under 10CFR50.59 and any change in the results of this evaluation will be reported to the Staff. Additionally, a response to the following three questions is provided as requested during the January 11, 1984 meeting. 1. Is CCPS designed for the 10CFR50 Appendix G curve or the Technical Specification curve for 10CFR50 Appendix G7 The proposed RHR COPS design will limit the RCS pressure increase during the postulated transients to values below the setpoint curve on Technical Specification Figure 3.4-4 for a given average RCS temperature. Figure 3.4-4 is the PORV setpoint curve necessary to prevent exceeding Appendix G limits. This curve will no longer be required in Technical Specifications once the RHR COPS design is approved. 2. Is COPS designed for charging pump letdown or safety injection flow? The RHR COPS is designed for the worst mass input case which is equivalent to the Safety Injection flow during COPS operation. 3. Does the ASME Code allow the proposed COPS? The RHR relief valves were designed in accordance with ASME Section III, Class 2 requirements. There are no Code requirements which prevent the use of these valves for the i COPS. l 1 i l i
..= Mr. Harold R. Denton Cold Gverpressure Protection System (COPS) February 2, 1984 Page #3 If you have any further questions, please contact us at your convenience. Very trgly yours, \\ I il 4 . UiXon, Jr. i AMP:OWD/fjc cc: V. C. Summer j T. C. Nichols, Jr./O. W. Dixon, Jr. E. H. Crews, Jr. E. C. Roberts l-W. A. Williams, Jr. D. A. Nauman J. P. O'Reilly Group Managers O. S. Bradham C. A. Price C. L. Ligon (NSRC) l G. J. Braddick D. J. Richards NRC Resident Inspector J. B. Knotts, Jr. NPCF File
- l: '
a CENERAL ARRANGEMENT OF Tile RilRS ISOLATION AND RELIEF VALVES TO PRESSURIZER _ __ A_oT_o __C_ L_o_S6__ R_E_ LIEF TANK l q l 'l p _O_f f_.w En A 6u_+5_ed t_. _______I__, l CuI (Tan 3) 0 c-g ia J r--{mJ])J Is o Gmam A l l a i 1 TRAIN A i = l >< l >< y l 1-8702A l 1-8701A 1-8708A RilRS ISOLATION RHRS RELIEF 5 LOOP 1 g 8 VALVES HOT VALVES g 8 LEG g l LOOP 1 l l H COLD I l TO RHRS LEC l l pugpg I l REACTOR I I I VESSEL l . P3 l l TO PRESSURIZER COLD I I RELIEF TANK LEG g g h i 1 i I g ganw &) % m h) LOOP 3 II F g-[ 4,I gq I- - l l >< l '"^'" " g 1-8701B g 1-87088 i CH g l-8702B p- ~ ~ ~ _] 1NSIDE l0UTSIDE fadawve PT oe 402 l dNd'*" REACTOR REACTOR 1 i CONTAINMENT CONTAINMENT Lauto_CteSc_ _ _ _ _ _ _ 1 ___ _ __ _ J e a}}