ML20085K067
| ML20085K067 | |
| Person / Time | |
|---|---|
| Site: | Dresden, Browns Ferry, 05000000 |
| Issue date: | 01/04/1974 |
| From: | Gilleland J TENNESSEE VALLEY AUTHORITY |
| To: | US ATOMIC ENERGY COMMISSION (AEC) |
| Shared Package | |
| ML20085K054 | List: |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, NUDOCS 8310200001 | |
| Download: ML20085K067 (2) | |
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Hr. F. E. Kruesi',' Director 73 Directorate of Regulatory Operations U.S. Atomic Energy Commission Washington, DC 20545
Dear Mr. Kruesi:
In conformance with paragraph 50.55(c) of 10 CFR 50, this is submitted as a final report on a design deficiency in the control logic of HPCI and RCIC systems of our Browns Ferry Nuclear Plant units 2 and 3.
Initial report of this deficiency was made to AEC-DRO Region II on November 10, 1973, and interim reports were submitted to your office on December 10 and December 14.
Corrective actions to be taken on units 2 and,3 involve removal of the llPCI and RCIC high reactor water level trips that currently originate in the Feedwater Control System, and the installation of l
I four additional qualified high reactor water level switches. These new switches, with the four existing switches, will be arranged in redundant piping manifolds such that the HPCI and RCIC will cach have four switches (two in each manifold) of which two are powered from the Division 1250-volt d.c. supply and two from the Division II 250-volt d.c. supply. The four switches for each turbine will energize a logic circuit that will trip the machine when either two of the existing switches or two of the new switches are closed by high reactor water level. Units 2 and 3 vill have these modifications made before fuel loading.
Interim corrective actions on unit 1 involved reversing the aspect of the relays in the tripping logic so that they had to be energized to trip, climinating the lockout feature so that manual reset of the t'
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tripping logic would not be required, and changing the power supply for one channel to a 250-voir d.c. supply through an inverter (see TVA abnormal occurrence report BFAO-7334W, November 11, 1973, E. F.
Thomas to John F. O' Leary). The corrective actions described above for units 2 and 3 have since been applied to unit 1.
Very truly yours, s
J. E. Gilleland Assistant to the Manager of Power CC:
Mr. Norman C. Moseley, Director Directorate of Regulatory Operations U.S. Atomic Energy Commission Region II - Suite 818 230 Peachtree Street, NW.
Atlanta, Georgia 30303 l
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