ML20246N045

Forwards AEOD/E906, Failure of Steam Generator Isolation Check Valve, Technical Review Rept.Rept Concludes That Regulatory Practice Has Not Identified That Steam Generator Isolation Check Valves Have Two Safety Functions

ML20246N045
Person / Time
Site:	Calvert Cliffs
Issue date:	08/30/1989
From:	Cintula T NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD)
To:	Rosenthal J NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD)
Shared Package
ML20246N050	List: ML20246N045 ML20246N058 ML20246N072 ML20246N093
References
AEOD-E906, NUDOCS 8909080024
Download: ML20246N045 (2)

Text

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AUG 30 1NB MEMORANDUM FOR: . Jack E. Rosenthal, Chief AEOD/E906

. Reactor Operations Analysis Branch Division of Safety Programs Office for Analysis end Evaluation of Operational Data THRU: George F. Lanik, Chief Reactor Systems Section GE & CE Reactor.0peraticns Analysis Branch Division'cf Safety Frograms Office for Analysis and Evaluation of Operational Data FROM: Theodore C. Cintula Reactor Systems Section GE & CE Reactor Operations Analysis Branch Division of Safety Programs Office for Analysis.and Evaluation of Operational Data

SUBJECT:

FAILURE 0F STEAM GENERATOR ISOLATION CHECK YALVE Enclosed for your information is a copy of my AEOD Engineering Evaluation Report on the failure of the steam generator isolation check valve of both units at Calvert Clifis.

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.The report suggests that a failed steam generator isolation check valve could lead to a mere severe steam line break accident than analyzed in the FSAR.

The failure of the steem generator isolation check vahe may permit both stcem generators to ccwcrir.cte in a postulated Steam ifne break scencrio. Thus, it is possible both steam generators may blow den simultaneously through a commer.

break in the sten ;1ue. With both steam generators blowing down, steam generator differential pressure may not be sufficient. to isolate AFW flow to the 3 ruptured stees generator. The continuation or feed during a blowdewn of two {

steam generators may result. in a more rapni end prolonged cooldown and a kn eater insertion of positive core reactivit.y than assumed i:: the FSAR with an i (Mgie cctive f ailure (the most reactive control element assembly in its fully withdrawn pen % ion after the reactor triph i

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t Jack E< Rosenthal < The. report concludes that regulatory' practice has not ' identified that' the steam generator isolation' check valves has two' safety functions. The. report suggests-

periodic testing for both safety fu ctions of-this valve _would be appropriate, .

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Theodbre C. Cintula Recctor Systems Section GE & CE Reactor Operations Analysis Branch Division of Safety. Programs -

Office for. Analysis and Evaluation of Operational Data

Enclosures:

As stated d 9

Distribution:

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.TCintula nik 6 $C789. (/ / /89 6

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