ML20080Q554

From kanterella
Jump to navigation Jump to search
Responds to Request for Addl Info Re NUREG-0737,Item II.F.2 Concerning Reactor Coolant Inventory Tracking,Core Exit Thermocouple & Subcooling Margin Monitor Sys.Westinghouse Subcooling Margin Monitor Meets NUREG-0587 Requirements
ML20080Q554
Person / Time
Site: Summer South Carolina Electric & Gas Company icon.png
Issue date: 02/17/1984
From: Dixon O
SOUTH CAROLINA ELECTRIC & GAS CO.
To: Harold Denton
Office of Nuclear Reactor Regulation
References
RTR-NUREG-0578, RTR-NUREG-0737, RTR-NUREG-578, RTR-NUREG-737, TASK-2.F.2, TASK-TM NUDOCS 8402240107
Download: ML20080Q554 (3)


Text

.

SOUTH CAROLINA ELECTRIC & GAS COMPANY post oprice 7e4 COLUMatA. SOUTH CAROLINA 29218 s

o. W. DIXON, JR.

vien enesioe~T February 17, 1984 NUCLEAR OPERATION $

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 Inadequate Core Cooling, NUREG-0737, II.F.2

Reference:

Thomas L. Novak letter to O. W. Dixon, Jr., dated 1/12/84

Dear Mr. Denton:

In the referenced letter the NRC summarized its review of the Reactor Coolant Inventory Tracking System, Core Exit Thermo-couple System, and Subcooling Margin Monitor System utilized at the Virgil C. Summer Nuclear Station. Also identified'were several questions and concerns which are addressed in this response.

1. The Staff has stated that the proposed backup core exit thermocouple display is not satisfactory since qualified equipment is required for the backup display. In our letter of August 26, 1983, from O. W. Dixon, Jr. to Harold R.

Denton, South Carolina Electric and Gas Company (SCE&G) stated that, in accordance with NUREG-0737, II.F.2, Appendix B, Criterion 1, and Regulatory Guide 1.97, Revision 2, the backup thermocouple display would not be qualified since it was a computer based display, and isolation of the lE input signals would be provided in an accessible location.

Regulatory Guide 1.97, Revision 2, Paragraph 1.3.1 states that for category 1 instrumentation, "where the instrumentation channel signal is to be used in a computer based display..., qualification applies from the sensor to and includes the channel isolation device." Before proceeding with this design, SCE&G obtained concurrence on the interpretation of qualification requirements from the Staff during telephone conversations in May 1983. Based on these conversations, SCE&G transmitted its August 26, 1983, letter and proceeded with design and procurement to implement a system using thermocouple isolators and the present subcooling margin monitor.

O!oohh L

- \

O Mr. Harold R. Denton Inadequate Core 7ooling, NUREG-0737, II.F.2 February 17, 1984 Page #2 Additionally, the following is provided as justification for acceptability of the current backup thermocouple display:

a) The present Westinghouse subcooling margin monitor uhich is used as the backup thermocouple display was purchased in spring 1980 and was decigned and built to meet NUREG-0578 requirements.

b) The analog isolator cablaets will be located in a room directly beneath the main control room in an aasily accessible area. In the unlikely event that the subcooling margin monitor is rendered inoperable from a seismic event, thermocouple readings can be manually taken at the isolator cabinets.

2. The Staff has stated that it is not clear where the reference junction compensation equipment is located.

Through the use of containment electrical penetrations with cromel and alumel conductors, the need for reference junctions inside containment has been eliminated. The reference junction compensation will be electronically performed at the input to the analog isolators which are located in the Control Building in a mild environment.

SCE&G provides-the following schedule for responding to Enclosure 2, Item 3 and Enclosure 3 of Mr. Novak's January 12, 1984, letter:

1. Enclosure 2, Item 3 - April 13, 1984.
2. Enclosure 3 - April 13, 1984.

D 1 6' Mr.: Harold R. Denton

-Inadequate Core Cooling, NUREG-0737, II.F.2 February 17, 1984 Page #3 4

Should there bet any questions, please notify us at your convenience..

Very truly yours,

/ /

O. W. xon t_,J .

JG:OWD/fjc cc: 'V. C. Summer a'

T. C. Nichols, Jr./O. W. Dixon, Jr.

E. H. Crews, Jr.

4 E.'C. Roberts W. A. Williams, Jr.

D..A..Nauman J. P. O'Reilly Group-Managers O. S. Bradham C. A. Price' C. L. Ligon (NSRC)

K. E. Nodland' R. A. Stough C. W. Hehl J. B. Knctts, Jr.

NPCF File 1

i f

I L-