ML20211C500
| ML20211C500 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 09/18/1997 |
| From: | NORTHEAST NUCLEAR ENERGY CO. |
| To: | |
| Shared Package | |
| ML20211C497 | List: |
| References | |
| NUDOCS 9709260226 | |
| Download: ML20211C500 (5) | |
Text
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s Docket Nos. 50-243 -
l M.2ft i
Millstone Nuclear Power Station, Unit No. 3 Chance to Technical Soecification Bases Section 2.2 (PTSCR 3-32-97)
Marked up Page 9709260226 970918 PDR ADOCK 05000423 P
PDR September 1997
March 11, 1991
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LIMITING SAFETY SYSTEM SETTINGS BASES Steam Gen'erator Water Level The Steam Generator Water Level Low-Low trip protects the reactor from loss of heat sink in the event of a sustained steam /feedwater flow mismatch resulting from loss of normal feedwater.
The s;iecified Setpoint provides..
allowances for starting delays of the Auxiliary Feedwater System.
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Low Shaft Soeed - Reactor Coolant Pumos The Low Shaft Speed - Reactor Ccolant Pumps trip provides core protection to prevent DNB in the event of a sudden significant decrease in reactor coolant pump speed (with resulting decrease in flow) on two reactor coolant pumps in any two operating reactor coolant loops.
The trip setpoint ensures that a reactor trip will be generated, considering instrument errors and j_
response times, in sufficient time to allow the DNBR to be maintained greater than the design limit following a four-pump loss of flow event.
Turbine Trio A Turbine trip initiates a Reactor trip.
On decreasing power the Reactor trip from the Turbine trip is automatically blocked by P-9 (a power level of approximately S0% of RATED THERMAL POWER); and on increasing power, reinstated automatically by P-9.
Safety Iniection Inout from ESF If a Reactor trip has not already been generHed by the Reactor Trip System instrumentation, the ESF automatic actuatier logic chanr.ls will initiate a Reactor trip upon any signal which initiates a Safety Injection.
The ESF instrumentation ebennel:. which initiate a. Safety Injection signal are shown in Table 3.3-3.
t Reactor Trio System Interlocks n,reer 1
The Reactor Trip System interlocks perform the following functions:
h P-6 On increasin power P-6 allows e manual block of the " N urce Range trip (i.
prevents prem re block of Source ge trip) and deener i es the high volt e to the detectors.
decreasing powpr
' Sour Range Level tri are automatically ret ivated and higk vol-ta restored.
/
p
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P-7 On increasing power P-7 automatically enables Reactor trips on low flow in more than one reactor coolant loop, reactor coolant pump low shaft speed, pressurizer low pressure and pressurizer high level. On decreasing power, the above listed trips are automa'tically blocked.
MILLSTONE - UNITE 3 B 2-7 Amendmant No.60 0006 n
Insert A -
On increasing power, P-U becomes active above the Interlock Allowable Value specified-on Table 2.2-1 to allow the manual block of the Source Range trip (i.e., prevents premature block of the Source Range trip during reactor startup) and deenergizes the high -
voltage to the detectors. On decreasing power during a reactor shutdown, Source Range -
Level trips are automatically reactivated and high voltage restored when P-6 deactivates.
The P-6 deactivation will occur at a value below its activation value and may be calibrated to occur below the P-6 Interlock Allowable Value specified on Table 2.2-1 to prevent overlap and chatter based upon the expected bistable drift O
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1 Docket Nos. 50-243 B16626 Millstone Nuclear Power Station, Unit No. 3 Chance to Technical Specification Bases Section 2.2 (PTSCR 3-32-97)
Retyped Page September 1997
LIMITING SAFETY SYSTEM SETTINGS BASES Steam Generator Water level The Steam Generator Water Level Low-Low trip protects the reactor from loss of heat sink in the event of a sustained steam /feedwater flow mismatch resulting from loss of normal feedwater.
The specified Setpoint provides allowances for starting delays of the Auxiliary Feedwater System, low Shaft Speed - Reactor Coolant Pumos The Low Shaft Speed - Reactor Coolant Pumps trip provides core protection to prevent DNB in the event of a sudden significant decrease in reactor coolant pump speed (with resulting decrease in flow) on two reactor coolant pumps in any two operating reactor coolant loops.
The trip setpoint ensures that a reactor trip will be generated, considering instrument errors and remonse times, in sufficient time to allow the DNBR to be maintained greater than the design above limit following a four-pump loss of flow event.
Turbine Trio A Turbine trip initiates a Reactor trip. On decreasing power the Reactor i
trip from the Turbine trip is automatically blocked by P-9 (a power level of approximately 50% of RATED THERMAL POWER); and on increasing power, reinstated automatically by P-9.
Safety In.iection Inout from ESF If a Reactor trip has not already been generated by the Reactor Trip System instrumentation, the ESF automatic actuation logic channels will initiate Reactor trip upon any signal which initiates a Safety Injection.
The ESF instrumentation channels which initiate a Safety Injection signal are shown in Table 3.3-3.
Reactor Trio System Interlocks The Reactor Trip System interlocks perform the following functions:
P-6 On increasing power, P-6 becomes active above the Interlock Allowable Value specified on Table 2.2-1 to allow the manual block of the Source Range trip (i.e., prevents premature block of the Source Range trip during reactor startup) and deenergizes the high voltage to the detectors.
On decreasing power during a reactor shutdown, Source Range Level trips are automatically reactivated and high voltage restored when P-6 deactivates.
The P-6 deactivation will occur at a value below its activation value and may be calibrated to occur below the P-6 Interlock Allowable Value specified on Table 2.2-1 to prevent overlap and chatter based upon the expected bistable drift.
P-7 On increasing power P-7 automatically enables Reactor trips on low flow in more than one reactor coolant loop, reactor coolant pump low shaft speed, pressurizer low pressure and pressurizer high level. On decreasing power, the above listed trips are automatically blocked.
MILLSTONE - UNIT 3 8 2-7 Amendment No. JP, 0548
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