ML18029A181
| ML18029A181 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 10/01/1984 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML18029A182 | List: |
| References | |
| NUDOCS 8410230226 | |
| Download: ML18029A181 (2) | |
Text
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E a given point at constant recirculation flow rate, and thus
'>:o protect aqainst the condition of a
MCPR less than 1.07.
ThiR rod block trip setting, which is automatically varied with recirculation loop flow rate, prevents an increase in the react. or power level to excess values due to control 'rod withdrawal.
The flow vaiiable t=ip setting provides substantial margin from fuel. dam;.ge, assuming a steady-state operation at the trip setting, over the entire recirculation flow range.
The margin to the Safety Limit increases as the flow decreases for the specified trip setting versus flow relationship; therefore, the worst case MCPR which could occur during the steady-state operation is at 108% of rated thermal power because of the APRM rod block trip setting.
The actual gower distribution in the core is established by specified control rod sequences and is monitored continuously by the in-core LPRM system.
C ~
Reactor Water Low Level Scram and isolation Kxce t Hain Sc,eamlines 4
The set point for the low level sc.-.am is above the bottom of t: he separator skirt.
This level has been used in transient analyses dealing with coolant inventory decrease.
The results reported in /SAR subsection 14.5 show. that scram and isolation of all process lines (except main steam) at tF>i" level adequately protects the fuel and the pressure 'barrier, because MCPR is greater than 1.07 in all cases, and system pressure
'does not reach the "safety valve settings.
The scram setting is approximately 31 inches below the normal operating ranqe and is thus adequate'to avoid spurious scrams.
D Turbine Sto Valve Closure Scram The turbine stop valve closure trip anticipates the pressure-neutron flux and heat flux increases that would result from closure of the stop valves.
Wi
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trip setting of 10K of valve closure from full open, the resultant increase in heat flux is-such that adequate thermal margins are mainta>>e even during the worst case transient that assumes the turbine bypass valves
>rc>>>ain closed.
(Reference 2).
Turb)ne control valve fast closure or turbine trip sera>>>
an icipates the
- pressure, neutron flux, and heat flux )ncreas<.
that << <<l<l r<.".ult from cont.rn) v>>lvc fast clos<<rc due rn lnnd rr >ecri< ~>> <<r <<v>> rol vn)v<
c)<<.,>>r<
duc
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,the start of control valv<
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n>
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valve c)osurc due to turbine trip.
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