ML19253C636
| ML19253C636 | |
| Person / Time | |
|---|---|
| Site: | Farley  |
| Issue date: | 11/26/1979 |
| From: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | Clayton F ALABAMA POWER CO. |
| References | |
| NUDOCS 7912060604 | |
| Download: ML19253C636 (1) | |
Text
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f/e UNITED STATES l')7 [g NUCLEAR REGULATORY COMMISSION g
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/s_ m REGION il o,
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131 MARIETTA ST., N.W., SUITE 3100 Q
ATLANTA, GEORGIA 30303 o
NOV 2 61979 In Reply Refer To:
RII:
348 50-364 s
Alabama Power Company Attn:
F. L. Clayton, Jr.
Senior Vice President Post Office Box 2641 Birmingham, Alabama 35291 Gentlemen:
The enclosed Circular No. 79-24 is forwarded to you for information. No written response is required. Should you have any questions related to your understanding of the recommendations on this matter, please contact this office.
Sincerely, nfn k James P. O' eill)
~
Director
Enclosures:
1.
IE Circular No. 79-24 i540 07!
2.
List of IE Circulars Issued in the Last Six Months
[
7912060
NOV 2 61979 Alabama Power Company -
cc w/ enc 1:
A. R. Barton Executive Vice President Post Office Box 2641 Birmingham, Alabama 35291 J.
T. Young Vice President-Production Post Office Box 2641 Birmingham, Alabama 35291 C. Biddinger, Jr.
Manager-Corporate Quality Assurance Post Office Box 2641 Birmingham, Alabama 35291 H. O. Thrash Manager-Nuclear Generation Post Office Box 2641 Birmingham, Alabama 35291 H. G. Hairston, III Plant Manager Drawer 470 Ashford, Alabama 36312 R. E. Hollands, Jr.
QA Supervisor 1540 072 Post Office Box U Ashford, Alabama 36312
Accession No: 7910250492 SSINS No. 6830 UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 November 26, 1979 IE Circular No. 79-24 PROPER INSTALLATION AND CALIBRATION OF CORE SPRAY PIPE BREAK DETECTION EQUIPMENT ON BWRs Description of Circumstances:
During 1976 tha Iowa Electric Light and Power Company identified and corrected a potential problem involving the core spray (CS) pipe break detection system at the Duane Arnold Energy Center (DAEC). The problem relates to the setpoint, function, and installation of the differential pressure (dp) instrument which monitors for a CS pipe break that is located in the annulus area of the reactor vessel (i.e., located outside the core shroud but inside the reactor vessel).
The installed instrument, range of 0 - 24 psid, was found deflecting downscale (i.e., reading negative psid) during operation.
The licensee's investigation of the downscale deflection revealed that the original piping arrangement and calibration did not adequately take into account the effect of density changes of the water in the pressure leg connections.
The original installation had the high pressure side of the dp instrument (see attached Figure 1) connected to the reference leg in the vessel (Figure 1 Connection X) and the low pressure side to the core spray piping outside the vessel but inside the drywell (Figure 1 Connection Y).
With the piping intact, this arrangement senses the pressure difference between bottom and top of With a break in CS piping in the annulus area the instrument then senses core.
the additional pressure drop across the separators (dp g 7 psi additional) and dryers (dp g 7-inches water). This installation was in accordance with GE design requirements.
Also in accordance with GE instructions the calibration of the dp instrument was performed with the reactor in the cold condition and the alarm was set to trip at 5 psid increasing. Because of this cold calibration the dp instrument then indicated full downscale negative during operation. This negative dp was due to the heat up of the reference leg (Figure 1 Connection X) which caused the fluid density to decrease as the plant reached hot conditions. The magnitude of this dp was determined to be about 3.5 psid following completion of the modification discussed below.
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