ML19209A426
| ML19209A426 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 09/14/1979 |
| From: | Stallings C VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| 678-081379, 678-81379, NUDOCS 7910030842 | |
| Download: ML19209A426 (3) | |
Text
6
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A N T,\\
VrROINIA Er.ECTRIC AND POwnB COMPANY Rrenwown,Vamorn Anoge p
. Il nio ; g g September 14, 1979 Mr. James P. O'Reilly, Director Serial No. 678/081379 Office of Inspection and Enforcement P0/FHT:baw U. S. Nuclear Regulatory Com=ission Docket Nos. 50-338 Region II 50-339 101 Marietta Street, Suite 3100 License Nos. NPF-4 Atlanta, Georgia 30303 CPPR-78
Subject:
IE Bulletin 79-21 North Anna Power Station Units 1 and 2
Dear Mr. O'Reilly:
We have reviewed the subject bulletin, " Temperature Effects on Level Measurements",
and herewith forward the attached response for North Anna Power Station Units 1 and 2.
Very truly yours, W'Nf C. M. Stallings Vice President-Power Supply and Production Operations cc: Director Office of Inspection and Enforcement Division of Reactor Operations Inspection Washington, D. C.
20555 1086 159 7910080 # 9 WOM
~
h;J.v OAL COPY i
IE BULLETIN 79-21 NORTH ANNA POWER STATION UNITS 1 AND 2 In response to IE Bulletin 79-21, the following liquid level measuring i
or are systems within the containment are used to initiate safety act ons Also included are used to provide post-accident monitoring information.
descriptions of the systems and the effect upon those systems,of a high energy line break inside the containment.
tive actions for these systems are included.
The Steam Generator (S/G) Level provides a reactor trip during a major S/G 1evel is also used to monitor 1.
secondary line break accident.
i the heat transfer capability of the secondary system follow ng any plant transients or accidents.
The S/G 1evel measuring system is an open-column reference leg system providing a signal to a 2 out of 3 logic activation system.
The effects of post-accident ambient temperatures following a high h
energy line break inside containment were determined by Westing ouse VPA-79-36 and the results were forwarded to Vepco in Westinghouse letterT dated August 29, 19 79.
line break temperature of up. to 280*F may occur following a high energy l error of within contain=ent which may result in an indicated S/G Le 20% span.
10% error in reference leg heatup effects.
North Anna initiated a satpoint change on the S/G This change was to correct for the On July 23, 1979,
'l Level Trip frcm 5% span to 15% span.
A further change environmental effects on the S/G 1evel transmitters.
is not to the setpoint to correct for the reference leg heatup effects In the case necessary because a redundant reactor trip is provide d by a Safety Injection and subsequent reactor trip will be initiate i ment the Righ Containment Pressure signal which occurs at a conta nN h
t t of pressure of 17 PSIA.this trip will initiate approximately one second after t e will the transient and the maximum ambient containment temperatureThis reactor trip be approximately 180*F at the time of this trip.will not be a h
ssure transmitters are located outside the containment.
Further corrective actions have been taken by incorporating precautions into North Anna Emergency Procedures dealing wit possibility of erroneous S/G Level indications during post-accident breaks.
conditions.
The Pressurizer Level measuring system is a sealed reference leg syste providing a signal to a 2 out of 3 logic activation system.
2.
No credit is taken in the safety analysis for this reactor trip Thus, the following a high energy line break inside containment.
environmental errors.
i086 i60
- The initial post-accident containment temperatures may cause an erroneous indication of pressurizer level but further analysis is required to quantify the effects.
1086: 161