ML19262A561
| ML19262A561 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom, Limerick  |
| Issue date: | 11/26/1979 |
| From: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | Boyer V, Daltroff S PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| References | |
| NUDOCS 7912060584 | |
| Download: ML19262A561 (1) | |
Text
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pa atov UNITED STATES
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NUCLEAR REGULATORY COMMISSION REGION I
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631 PARK AVENUE e'
KING OF PRUSSIA, PENNSYLVANIA 19406 Docket Nos. 50-352 fl0V 2 6 1979 50-353 50-277 CO-R77 Philadelphia Electric Company Attention:
Mr. V. S. Boyer Vice President Engineering and Research 2301 Market Street Philadelphia, Pennsylvania 19101 Gentlemen:
The enclosed IE 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,
/ k tb =
Boyce H. Grier
'~~~ Director
Enclosures:
1.
IE Circular No. 79-24 w/ Attachment 2.
List of Recently Issued IE Circulars CONTACT:
W. H. Baunack (215-337-5253) 1529
'-08 529 7912000 f
ENCLOSURE 1 Accession No: 7910250492 SSINS No. 6830 UNITED STATES NUCLEAR REC iATORY COMMISSION OFFICE OF INSPEtiION AND ENFORCEMENT WASHINGTON, D.C.
20555 IE Circular No. 79-24 Date:
November 26, 1979 Page 1 of 3 PROPER INSTALLATION AND CALIBRATION OF CORE SPRAY PIFE BREAK DETECTION EQUIPMENT ON BWRs Description of Circumstances:
During 1976 the 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 celates to the setpoint, function, and installation of the differential pressure (dp)' instrument whicn 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 deflectic 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) connet.t.d to the reference leg in the vessel (Figure 1 Connection X) and the low pressure side to tje core spray piping outside the vessel but inside the drywell (Figure 1 Conrection Y).
With the piping intact, this arrangement senses the pressure differe nce between bottom and top of core.
With a break in CS piping in the anntlus area the instrument then senses the additional pressure drop across the separators (dp p* 7 psi additional) and dryers (dp q 7-inches water).
This install.ition 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 concition and the clarm was set to trip at 5 psid increasing.
Becau3e of this colc calibration the dp instrument then indicated full downscale negative during oreration.
This negative dp was due to the heat up of the reference leg (Fiqur(: 1 Connection X) which caused the fluid density *.o decrease as the plant reache was detrrmined to be about 3.5 psid foi discussed below.
1529 309 DUPLICATE DOCUMENT Adding the 3.5 psi downscale deflection in a total required deflection of 8.5 p Entire document previously Since the total dp availa!le across the entered into system under:
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