ML19319B891
| ML19319B891 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 05/02/1977 |
| From: | Roe L TOLEDO EDISON CO. |
| To: | Stolz J Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8001290616 | |
| Download: ML19319B891 (4) | |
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Toledo Edison Company 5/2/77 l
Mr. John F. Stolz Toledo, Ohio c4rc sEcavco Lowell E. Roe 5/3/77
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Consists of revised Sec. 7.6.1.1.2 of the Unit No. 1 FSAR regarding overpressure protection.....
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Davis-Besse Unit No. 1
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D-B The auto =atic closure of the valves cannot be bypassed =anually. MLnual oper'-
ation is prevented as long as the RC pressure is above the setpoint pressure of the signal comparator and pressure switch. At shutdown, the valves will l22 21T be opened and power re=oved as discussed in seccion 9.'.5.5 (see NOTE above).
p The pressurizer heater trip interlock signals are derived fro = the sign 13.
co=parators located in the SFAS cabinets. The signal comparators receive their reactor coolant pressure signal fro = the RC loop 1 or 2 vide range pressure trans=itter that supplies the signal for the corresponding SFAS cabinet.
The pressurizer heater trip interlocks are provided by means of relay logic in redundant essential relay cabinets. A separate output relay is provided for the essentially povered pressurizer heater control circuits and the non-essentially povered pressurizer heater control circuits, in each redun-dant " trip interlock logic." A contact fro = the same signal comparator in the SFAS that provides the RC pressure closing signal to one DH valve is used in one " trip interlock logic" to indicate RC pressure above 280 psig.
A sisilar signal co=parator is provided in a redundant SFAS chsnnel for the other " trip interlock logic." To provide li=it switch contacts to indicate 27 that either valve is not fully closed into each redundant " trip interlock logic," a ste=-nounted li=it switch is provided on both DH-ll and DE-12.
Each ste=-nounted switch is redundant to the limit switch provided in the motor-operator. Thus, all the necessary viring into the " trip interlock logic" is co=pletely separate and independent.
Valves DH-ll and DH-12 are automatically closed by RC pressure signals as l
1 described above and both are located inside the CV.
Therefore, the valves are not controlled by the SFAS.
7.6.1.1.3 Supporting Syste=s The nor=al decay heat re= oval valve control system obtains control pcver frc=
the essential power supply (Chapter 8).
7.6.1.1.L Portion of System Not Required for Safety The alar =s to the station annunciator and station ec=puter are not required for safety.
l 7.6.1.1.5 Drawings l
Electrical sche =atic diagra=s of the nor=al decay heat removal valve control syste= are shown in Figures 7-8A, 7-83, 7-8C, and T-8D.
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