ML20043B004

Provides Addl Info Re Automatic Depressurizer Sys (ADS) Timer Concerning Engineering Operating Procedures.Ads Actuation Should Be Allowed to Occur & Quickly Depressurize Vessel,If High Pressure ECCS Cannot Control Water Level

ML20043B004
Person / Time
Site:	05000605
Issue date:	05/16/1990
From:	Recasha Mitchell GENERAL ELECTRIC CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
EEN-9020, NUDOCS 9005240043
Download: ML20043B004 (1)

Text

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GE Nuclear Energy .

canwinc caw, US Curtner Aenue, Son Jtue. CA 95125 MFN No.050-90 Docket No STN 50-605 EEN-9020 Document Control Desk ,

U.S. Nuclear Regulatory Commission Washington, D.C. 20555

- Attention: Charles L Muer, Director ..

Standardization and Non-Power Reactor Project Directorate

Subject:

Additionai Information Concerning the ADS Timer

. The following provides some additionalinformation concerning the ADS timer with respect to the Engineering Operating Procedures (EOP).

There are two. instances in the. EOPs where the operator is !aeructed to prevent ADS actuation.'

The first is during an ATWS event. The second is when the operator believes that the reactorL water level may go below Low Water Level (LWL) 1 setpoint but will remain ~ above the top of the-active fuel'(TAF) without ADS actuation.' In either case, the ADS timer is oflittle consideration since the water levelis above the LWL.1 setpoint when the decision to prevent' ADS is made.

For the ATWS case, the reactor water level is being controlled above the LWL 1-setpoint by the -

high pressure makeup systems when the decision is made to prevent ADS actuation and reduce power by lowering the water level to TAF. For the second case, sinec ne distance from the LWL 1 setpoint to TAF is only about 1 foot, the operator must decide to preent the ADS as the reactor water level approaches the LWL 1 setpoint. .For small LOCAs, there e sufficient time (about 3 minutes) for the high pressure ECCS to begin injection and control the water level before the LWL -

1 setpoint is reached. If the high pressure ECCS cannot control the levelit is prudent to allow the ' ,

ADS actuation to occur and quickly depressurize the. vessel to gain the additional reflooding 1 capacity of the low pressure ECCS. 1 Sincerely, Q. C .

- R. C. Mitchell, Acting Manager '

Regulatory and Analysis Services M/C 382, (408) 925 6948 "

a 1 cc: . F. A. Ross (DOE) D. C. Scaletti (NRC) G. Tho.nas (NRC) -

D. R. Wilkins (GE) J. F. Quirk (GE) F. M. Paradiso (GE) g524co43.900516

• A O m 05000605 4 iPDC m .

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