ML19260B114
| ML19260B114 | |
| Person / Time | |
|---|---|
| Site: | Trojan File:Portland General Electric icon.png |
| Issue date: | 11/26/1979 |
| From: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Goodwin C PORTLAND GENERAL ELECTRIC CO. |
| References | |
| NUDOCS 7912070018 | |
| Download: ML19260B114 (1) | |
Text
/
'o,j UNITED STATES E\\'
NUCLEAR REGULATORY COMMISSION g.l-
- '.: c REGION V
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1990 N. CALIFORNI A BOULEVARD e*
SUITE 202, WALNUT CREEK PLAZA I
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WALNUT CR EEK, CALIFORNI A 94596 November 26, 1979 Docket No. 50-344 Portland General Electric Company 121 S. W. Salmon Street Portland, Oregon 97204 Attention: Mr. Charles Goodwin, Jr.
Assistant Vice President Gentlemen:
The enclosed Circular No. 79-24 is forwarded to you for information.
No written response is required. Should you have any questicns related to your understanding of the recommendations on this matter, please contact this office.
Sincerely,
[ LYk~,c LC-R. H. Engelken Director
Enclosures:
1.
IE Circular No. 79-24 2.
Recently Issued IE Circulars cc w/ enclosures:
C. P. Yundt, PGE F. C. Gaidos, PGE 15i7 229 7912070 ()/[
Accession Mo: 791025049?
SSIt'S No. 6330 IPlITED STATES t1UCLEAR REGl!LATORY C0'"11SSIO'l 0FFICE OF INSPECTIn't Ahl E?! FORCE'1EtiT
'fASHINGT09, D.C.
21555 November 26, 1979 IE Circular No. 79-24 oROPED I'!STALLATIO!! AND C ALIBRATIO!! 0F CORE SDRAY-PIDE BREAK 9FTECTInft EQUID'1E!!T O'i SPs Descriotion of Circurstances:
Durina 1976 the Iowa Electric Light and Power Conoany identified and corrected a potential problen involvina the core scrav (CS) oine break detection systen at the Ouane Arnold Enerqy Center (OAEC). The aroblen relates to the setooint, function, and installation of the differential pressure (do) instrument which nonitors for a CS pine 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 instrunent, rance of 0 - 24 osid, was found deflecting downscale (i.e., readino negative osid) durino operation.
The licensee's investigation of the downscale deflection revealed that the oriainal oioina arranqerent and calibration did not adequately take into account the effect of density chanqes of the water in the pressure leg connections.
The criainal installation had the high pressure side of.the dp instrument (see attached Fioure 1) connected to the reference leo in the vessel (Fioure 1 Connection X) and the low oressure side to the core sorav oicino outside the vessel but inside the drywell (Ficura 1 Connection V).
With the oicino intact, this arranaenent senses the pressure difference between botton and too of core.
Pith a break in CS oicino in the annulus area the instrurent then senses the additional oressure droo across the senarators (do $7 osi additional) an'i drvers (dp # 7-inches water). This installation was in accordance with GE desian requirements.
Also in accordance with GE instructions the calibration of the dp instrument was cerforned with the reactor in the cold condition and the alarn was set to trio at 5 osid increasino.
Decause of this cold calibration the do instrument then indicated full downscale neaative duriro coeration.
This neaative do was due to the heat un of the reference loo (Finure 1 Connection X) which caused the fluid density to decrease as the niant reached hnt conditions. The naanitude of this do was determined to be about 3.5 nsid followino concletion of the rodification discussed below.
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