ML20053A027
| ML20053A027 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 05/17/1982 |
| From: | Nichols T SOUTH CAROLINA ELECTRIC & GAS CO. |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8205240447 | |
| Download: ML20053A027 (5) | |
Text
.
4 SOUTH CAROLINA ELECTRIC Sc GAS COMPANY Post omer mox 7e4 COLUMBI A. S. C. 29218 May 17, 1982 Mr. Firold R. Denton, Director Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Ca mission Washington, D.C.
20555
Subject:
Virgil C. Sunner Nuclear Station Docket No. 50/395 Radiation Monitoring
Dear Mr. Denton:
A description of radiation monitor RM-G7 is described in Chapter 12.1 of the Virgil C. Sunner Nuclear Station FSAR. Recent information from the plant indicates that the 300 millicurie CS-37 source provided with the detector 'is not adequate for the detector to read on scale.
South Carolina Electric & Gas Cmpany has decided to forgo the use of the source since it is not required to demonstrate the functional capability of the detector. A copy of marked up FSAR pages is provided. They will be included in the next FSAR amendment.
If you have any questions, please let us know.
Very truly yours, I
T. C. Nichols, Jr.
Senior Vice President Power Operations 1
RBC:'IG:Ikb l
Attachment I
cc:
V. C. Sunner (w/o attach.)
G. J. Braddick G. H. Fischer (w/o attach.)
J. L. Skolds H. N. Cyrus J. B. Knotts, Jr.
T. C. Nichols, Jr.
(w/o attach.)
B. A. Bursey M. B. Whitaker, Jr.
NPCF l
J. P. O'Reilly File H. T. Babb i
D. A. Nauman C. L. Ligen (NSRC)
QgO W. A. Willians, Jr.
U I
R. B. Clary O. S. Bradham A. R. Koon M. N. Browne i
9205240447 820517 PDR ADOCK 05000395 A
O of the gamma dose rate levels in selected areas of the plant.
Reliable power for the instrumentation 'is obtained from the diesel backed, 120 l
volt instrument buses.
We local audible and visual alarm are powered from the 120 volt buses.
The movable channel is powered from 120 volt outlet.
f Except for the movable unit, which is equipped for local recording and 4
indication, the measured dose rate levels are indicated and recorded on the area radiation monitoring system control panel located in the con-trol room.
Local indication is provided for each monitor except 10 7
RM-G18.
Each area radiation monitor is equipped with two adjustable alarm levels ($G 7).and high) and a channel failure and/or loss of power lert fg 3
luu!T R ru s <rr n) alarm A Wese alarms from tne rixed monitors) are connected to an 4
annunciator panel on the radiation monitoring system control -panel in the control room.
Each area radiation monitor, except for RM-G17A&B and 18 RM-G18, is provided with a local audible and visual alarm located near the detector or local readout.
The manipulator crane area monitors each have an audible alarm in the fuel handling area.
The alarm setpoints are adjustable and are dependent upon the location of the individual monitors.
In general, the alert setpoint is adjusted to a level below the high setpoint to provide warning of a change in normal plant opera-tion conditions. The high setpoint is generally established by the zone limitations established for each area. The gamma dose rate resulting from a postulated loss of coolant accident (LOCA) is monitored by the yg high range reactor building monitor, RM-G7 and RM-G18.
RM-G7 located in a reactor building penetration (see Figure 6.2-60a), is designed to withstand a seismic event and is not exposed to the anticipated LOCA environment.
RM-G18, located inside the containment, is designed to f
meet IEEE-323-1974, IEEE-344-1975, ANSI N320-1978.
Radiation monitor RM-G7 has a gamma sensitive stainless steel ion-cham-7 ber fully inserted in the two inch pipe inside containment penetration
\\
No. 309 shown in Figure 6.2-60a which extends into.the containment, is located at 237 -50' at the 477 foot elevation. The energy response of the detector is sensitive to 60 KEV.
This low energy response is attenu-ated by the penetration end cap.
The design temperature limit of the detector is 300 C and the stainless steel 3 2.
12.1-26 AMENDMENT M "J~ ^ O t.UCU CT, 1000
[
i INSERT A ~ page 12,3_gg Channel RM-G7 provides alarms for alert, high, and upon loss ofs power to the alarm module.
I
{
clcd coaxial cables are w21ded to the detector housing with interfcce connections located in the penetration access area.
Local indication and alarm is located in the 'enetration access area and indication is p
k provided near the entrance to the containment personnel access hatch and in the control room.
The design range was 10 to 10 R/hr, however
-13 with a detector sensitivity of 4.5x10 amps /R/hr. and the 8 - decade 8
continuous analog readout, the range is approximately 2.2 to 2.2 x 10 R/hr.
The analog signal is recorded on a multipoint recorder in the control room radiation monitoring system panel.
High gamma dose rate es cad /;r dann! frilure :: annunciated in the control room.
Instrument power is obtained from the B-Train diesel backed 120 Vac.
The detector and control room readout have been seismically qualified by testing to meet criteria equivalent to the requirements of Regulatory Guide 1.100.
Radiation Monitor RM-G18, added to the radiation monitoring system to meet the intent of NUREG-0578, provides a diverse means of measuring the containment for high level gamma radiation.
The detector for RM-G18 is a stainless steel gamma sensitive ion-chamber that is wall mounted inside the containment above the 463 foot floor elevation, reference 20 Figure 1.2-6.
A continuous 7 - decade analog readout is provided in the control room radiation monitoring system panel with an indication range of 1 to 10 R/hr.
The detector energy response is sensitive to 60 KEV, -15% at 80 KEV and within + 10% from 100 KEV to 3 Mev.
The analog signal is recorded on a multipoint recorder which was seismically qualified with the radiation monitoring system panel. High gamma dose rate or channel failure are annunciated in the control room.
Instrument power is obtained from the A-train diesel backed 120 Vac.
The detector and control room readout have been type tested for seismic
(
qualification to meet the requirements of Regulatory Guide 1.100 and are designed to meet the requirements of IEEE-323(1974). The detector and its interface cable-connector assembly have been type tested for LOCA environment to meet Regulatory Guide 1.89.
Calibration of the high range containment gamma monitors shall be performed during refueling and shall consist of verification of the readouts by a calibrated current source and by a point source verification of response of the ion-chamber
(
detectors in the low range.
"J 1 AMENDMENT to-I's, W 2 om, 33; 12.1-26a
f i
Monitor RM-G18 incorporates a built-in periodic electronic tect signs 1 to verify the function of the detector and cable.
"e..ite-
"J: G7 u pr..-ided.ith ; shicided :diciact p; ::ur:c, appre:Errtc-ly 30G
-4114e'2rie 09-137, which een be incerted i=t
.djacco 5 ir.ch pipc
.o 3'
-11 2.x; i: :Lc dc:cc::. Enseneir: :f th*: :: rre prefider :
26 reepe--- u ririr-*:^- "ithir the fir:t accedc.
The detector for RM-G7 l
6 was calibrated up to 2.35 x 10 R/hr as verified by dosimetry in l
,9 p
accordance with ASTM standard D-1617-72.
The gamma dose rate in the reactor building manipulator crane area, during refueling, is monitored by RM-G17A and RM-G17B.
Either one,.upon detection of high activity or loss of signal, interlock to close the 15
^
purge discharge valves (Figure 11.4-1).
These monitors are not required during normal operation.
Area radiation monitor electronics have a five decade logrithmic scale with a nominal measurement accuracy of +25 percent of the reading.
The precision is 215 percent at all levels. Area radiation monitors are calibrated on a routine basis and af ter any maintenance work is per-formed on the detector by exposure to a standard radioactive source with its calibration traceable, directly or indirectly to the National Bureau of Standards. Calibration of the high range area monitor, RM-G7 and RM-G18 uses a calibrated electrical current source to verify the 18 3L performance of t b re a cl ou TS T%
O 3 1.
12.1-26b AMENDMENT -iML Tu n
- u;t
- ;;;, 1982