ML19257D523
| ML19257D523 | |
| Person / Time | |
|---|---|
| Site: | McGuire, Mcguire  |
| Issue date: | 01/29/1980 |
| From: | Parker W DUKE POWER CO. |
| To: | Baer R, Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8002040524 | |
| Download: ML19257D523 (5) | |
Text
~*
.w DUKE POWER COhiPANY Powra Bcito No 4c2 SOUTH CHURCH STREET, CHARI.OTTE N. C. 28242 WI LLI AM O. PA R K ER. J R.
s.c c p.c.' o r e January 29, 1980 c c -o~c ^aca 7c4 S. tan Paco scviose 373-4083 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, DC 20555 Attention:
Mr. Robert L. Baer, Chief Light Water Reactor Project Branch No. 2 Re: McGuire Nuclear Station Units 1 and 2 Docket Nos. 50-369, 50-370
Dear Mr. Denton:
Attached is the response to the information requested in Mr. Robert L. Baer's letter of October 22, 1979, concerning our proposed adoustic leak detection system. The attached. consolidates the information provided in Attachment 6 to my letter of August 31, 1979. With the submittal of this information Duke Power Company considers item number 6 on the NRC Staff's milestone chart to be resolved.
Very truly yours, A 4.
AN
/
William O. Parker, Jr.
GAC/sch Attachment 1866~229
/g bpROGeg,%,
- s BOO l o
E 5
50 th l
Anniversary
%,"owsa s*/
9002040 6
52'-
ATTACHMENT 1 MCGUIRE NUCLEAR STATION Acoustic Leak Detection System The Acoustic Leak Detection System is designed to provide augmented leak detection capability at six locations on the reactor coolant pressure boundary. This system monitors the cold leg accumulator injection lines at the first elbow cff reactor coolant system loops A, C, and D.
This system consists of piezoelectric crystal sensors, local preamplifiers, and a multiplexer, each located inside the containment and signal processing equipment located in the control room area. A system alarm is provided on the main control board with individual channel alarms located on the signal processing equipment cabinet. Coaxial cable is used in this system to minimize electrical interference. The Acoustic Leak Detection System is powered from the 120 VAC battery - backed Auxiliary Control Power System.
Leak detection systems of this type, long used by the petroleum industry to monitor pipe lines, operate on the principle that leaks from high pressure fluid piping emit broad-based acoustic signals. As these signals travel through the piping material, they can be detected by piezoelectric crystal transducers. These crystals are chosen to be resonant at very high frequency (typically 200 to 300 kilohertz) to discriminate against low frequency noise created by vibration and fluid flow through piping and to optimize leak detection capability.
s Tests have been run on the type detectors used at McGuire Nuclear Station for the leak detection system. These tests were performed.by the manufacturer to establish the response of detectors to various leak rates. The results of this testing have shown the detector output signal is linear with respect to mass flow rate and independent of hole size, system pressure, and escaping fluid properties. The detectors were tested over a range of system pressures from 200 to 2000 psig and hole sizes from 1 mil to 10 mils.
The test results are shown in Figure 1.
The detector has a full range output of 1 volt which corresponds to a leak rate of 10-2 lb/sec. The main amplifier gain is adjustable up to a maximum of 63 db.
This corresponds to a theoretical sensitivity of 7 x 10-6 lb/sec.
(This is the flow rate from a crack of equivalent area of a 0.24 mil diameter hole which was calculated based on critical flow from the hole at reactor coobnt loop normal operating pressure and temperature.) The actual useable sensitivity will depend on background noise generated during plant operation.
Testing will be performed during plant startup to determine background noise and will determine the gain setting of the amplifier to optimize the highest gain setting without producing false alarms due to noise transients.
The acceptance criteria for the system is to initiate an alarm at a leak rate of 10-3 lb/sec.
This corresponds to a through-wall crack with an effective area of a 2.86 mil diameter hole. The diameter of this hole is several orders of magnitude smaller than the allowable crack size for this piping.
(See Appendix IV of the report " Augmented Inservice Inspection for Pipe Rupture Protection". Report No. SRG-78-01 Revision 1 submitted September 29, 1978.
As discussed in Appendix IV, the allowable crack size in this piping for the longitudinal through-wall crack is 4.09 inches and for the circumferential 1866 230 Page 1 of 2
through-wall crack is 6.76 inches.)
The McGuire Acoustic Leak Detection System is designed to detect leaks as described above. The system multiplexer, located inside the containment, scans the six transducers located on the cold leg accumulator injection lines and sends the signals to the signal processing equipment located in the control room area. A scan rate of three seconds per channel is used to permit the true measurement of a signal while providing an acceptable total scan time. The signal processing electronics and indicator assembly are located in the control room area. This assembly receives the signals from the multiplexer, conditions and measures them, and compares them with their corresponding channel alarm setpoint.
In the event that a channel exceeds its alarm setpoint, an alarm light on the signal processing cabinet will be turned on and latched for that particular channel. Additionally, the system alarm located on the main control board will be initiated. Built-in test features allow semi-automatic testing while the system is on line. A block diagram of this system is shown in Figure 2.
Upon receipt of an alarm, the operator will ve-ify the leak by cross checking with other sensors that are in close proximity to the channel in alarm. These sensors should show an elevated signal or possibly an alarm depending on the magnitude of the leak. Once a leak is verified, the unit must be brought to hot standby within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and cold shutdown within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br /> in accordance with the McGuire technical specifications.
1866 231 Page 2 of 2
L L
V l
s 9
C r.-
L C +0 l
4 lAON Wt. F E G
6 i 3 t
E TAE l.CA K E E
R 4I
%EU l
2 LS
'L C
4 FVH i*01 I
9 I 8 I 7 I
G I
S
)
I 4
CE 9
[
I 3
F; L
e
(
I 2
E ToC 4a 0
E I1 L
I 9 b
I 7
I 0
I 5
I 4
I 3
2
& && nun oq.- 9 ' _1v hT2tu ~ i u
N J_12~.3F 5
1 t
F
<A
-O I
O 0
0 0
0 2
4 6
8
McGuire fluclear Station Acoustic Leak Detection System Block Diagram Tran9fucer Preamp Signal Processing Equipment
/
N h
\\
A
/
System Alarm
[
S i g r.a l Amp Cond.
DVM liultiplexer
[
Multiplexer Control
/'
\\
00 Ch CD
/
~
ww Containment Pene t ra t ion FIGURE 2