ML19247A701
| ML19247A701 | |
| Person / Time | |
|---|---|
| Site: | Indian Point, Surry, North Anna  |
| Issue date: | 06/22/1979 |
| From: | Bryan S, Klingler G, Nolan F NRC OFFICE OF INSPECTION & ENFORCEMENT (IE) |
| To: | |
| References | |
| PNO-79-185, NUDOCS 7908020044 | |
| Download: ML19247A701 (1) | |
Text
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PRELIMINARY NOTIFICATION PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE--FNo 185 This preliminary notification constitutes EARLY notice of an event POSSIBLE safety or public interest significance.
The information gre_sented is as initially received without verification or evaluation and is basically all that is known by IE staff on this date.
FACILITY: Virginia Electric and Power Company North Anna and Surry Power Stations Docket Nos.
50-338, 50-339, 50-280 and 50-281 Hineral and Surry, Virginia
SUBJECT:
F7NCONSERVATIVE ANALYSIS RESULTS OF HIGH ENERGY LINE BREAK INSIDE LCh fAIIGENT ab Westinghouse informed their customers and provided a verbal Part 21 report to I&E of a conconservative analysis results of high energy pipe break occidents inside containment specifically concerning errors generated in the str2am generator level indication sensors.
Westinghouse informed Virginia Electric and Power Company of these results on June 21, 1979.
In the case of a feedvater pipe break, where containment temperatures could reach 280 degrees F, the higher temperature would affect the steam generator level reference leg causing a +10 percent level error.
This error would delay initiation of a steam generator low-low level indication and, therefore, delay initiation of auxiliary feedvater.
The analysis for a main steam lice break in containment generates a _4_00 degree F containment te=perature and a +21 percent error in steam generator level.
The licensee is evaluating this infomation and intends to generate supplemental orders to their customers.
Media interest is not expected.
Neither the licensee nor the NRC plan a neus release.
The Cocnonwea".th of Virginia has been informed.
North Anna Unit 1 is operating, Surry Units 1 and 2 are shutdown for long term maintenance.
Region II (Atlanta) received notification of this occurrence by telephone fro:n the Surry resident inspector at 9:00 a.m. on June 22.
Contact:
G. Klingler, IE x28019; F. Nola, it x28019; S. Bryan, IE x28019 Distribution:
Transmitted H St b T. Y Bradford S. J. Chilk, SECY Chairman Hendrie Cocr.
Cocsissioner Kennedy Com ss a Aber C. C. Kaccerer, CA ACRS (For Distribution)
Co:=sissioner Gilinsky g
p.45 Transmitted:
MNBB P. Bldg 4:4;r V. Stello, IE L. V. Gossick, EDO H. R. Denton, FRR Region L 9/(/a H. L. Ornstein, EDO R. C. DeYoung, NRR J. J. Fouchard, PA R. J. Mattson, NRR
R. G. Ryan, OSP D.Eisenhut,gR J. J. Curmings, OIA H. K. Shapar, ELD SS Bldg fe b R. Minogue, SD W. J. Direks, NMSS
- 3. Levine, RES
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g 0 0 YP' PRELIMINARY NOTIFICATION
POWER AUTHORITY OF THE STATE OF NEW YORK INDIAN POINT NO. 3 NUCLEAR POWER PLANT P. O. BOX 215 BUCH ANAN. N. Y. l os t !
TELEPwoNE: 914 739-8200 WAt b.,
p' June 22, 1979 IP-NAP-5146 Docket No. 50-286 License No. DPR-64 Boyce H. Grier, Director Office of Inspection and Enforcement Region 1 U. S. Nuclear Fegulatory Commission 631 Park Avenue King cf P ussia, Pennsylvania 19406
Dear Mr. Grier:
In accordance with the Technical Specifications of Facility Operating License No. DPR-64, the following describes Reportable Occurrence (LER) 79-006/01T-0.
This event is the type defined in Technical Specification 6.9.1.7 (h).
On June 21, 1979, the Power Authority was notified by our Nuclear Steam Supplier, the Westinghouse Electric Corporation, of an error in the less conservative direction in their analysis of high energy line breaks incide containment.
3reaks cf this type can result in heatup of the steam generator level ceasure=ent reference leg resulting in a decrease of the water column density with a con-secuent apparent increase in the indicated steam generar.or water level (i.e., apparent level exceeding actual level).
This potential level bias could result in delayed protection signals (reactor trip and auxiliary feedwater initiation) which are based on low-low steam gen-erator water level.
In the case of a feedline rupture, this adverse environ =ent could be present and could delay or prevent the primary signal arising from declining steam generator water level (low-low stea= generator level).
Containment oressure and safety injection provides a backup signal which initiates a trip before a containment temperature of 280 F. is reached.
This trip is conservatively set at 2.0 psig. Westinghouse has calculated that raisin;; the steam generator low-low level setpoint by 10 per cent of span would cc pensate for the effects of this temperature.
Since the Power Authority's calibration procedures already use a value of 15 per cent of scan as coposed..tn the Technical Specification valtC9-
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trip of 3. psig as opposed to Te MDUPLICATEDOCUMENT the change in setpoint recoc=end c; g Entire docur'.ent previously entered
-rurtner evaluation will be into system under:
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