ML19289D184

From kanterella
Jump to navigation Jump to search
Informs NRC of Steps Taken to Correct Error in Calculation of LOCA Peaking Factor Shape Limits.Corrective Action: Implementation of Administrative Procedure to Lower Input Values by 1.5% to Accomodate Nonconservatism
ML19289D184
Person / Time
Site: North Anna Dominion icon.png
Issue date: 02/16/1979
From: Brown S
VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To: James O'Reilly
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
575B, NUDOCS 7902230179
Download: ML19289D184 (1)


Text

l 6 t Vepco ____

Februa ry 16, 1979 Mr. James P. O'Reilly, Director Serial No. 575B Office Inspection & Enforcement PSE&C/LCK:LO314 U. S. huclear Regulatory Commission Region II Docket No. 50-339 101 Marietta Street, Suite 3100 Atlanta, Georgia 30303

Dear Mr. O'Reilly:

In accordance with 10CFR50.55(e), the NRC, Region II, was notified on October 6, 1973 that the North Anna Unit 2 Axial Power Distribution Monitoring System (APDMS) provided by Westinghouse Electric Corporation contained a non-conservatism capable of causing an error in the calculation of LOCA peaking f actor shape lirait s. This error was caused by a calculational round off which increased the set point above the desired value by as much as 1.1%.

This deficiency'will be correctec by implementing an administrative procedure which lowers the input values used by the APDMS 1.51,in order to accomodate the

.non-conservatism in the limit setpoint values calculated by the APDMS. This administrative precedure is presently being used on North Anna Unit 1.

It should also ce mentioned that safe operation of the unit could continue without APD.iS since full backup capability is provided on the unit's P250 plant computer systera or by manual calculations. This backup capability is provided in accordance with the proposed North Anna Unit 2 Technical Specifications Section 4.2.6.

Since this deficiency has now been conservatively taken into account, and since alternate acceptable means of performing axial power distribution surveillance are available, it is considered that this item is res91ved.

We consider this to be the final report under the provisions of 10CFRS50.55(e). If you require any further information at this time, please contact us.

- Ter drul 'yours, f ,

j y /

( //y s bYka

- S.!C. Brown, Jr.

Senior Vics-President - Power Station Engindering and Constrtjction cc: jMr. John G.' Davis, Acting Director Office of= Inspection & Enforcement Mr. Harold R. Denton, Director 90 s

Office of Nuclear Reactor Regulation '

3 ,

7 9 0 2 2 3 0 /T7 d