ML17199W197
| ML17199W197 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 03/28/1988 |
| From: | COMMONWEALTH EDISON CO. |
| To: | |
| References | |
| 4418K, NUDOCS 8804110086 | |
| Download: ML17199W197 (8) | |
Text
DRESDEN II DPR-19 Amenctnent No.JYf,~, J' TABLE 3.2.2 INSTRUMENTATION THAT INITIATES OR CONTROLS THE CORE AND CONTAINMENT COOLING SYSTEMS Hin. No. of Operable Inst.
Channels per
!!:.!P System CI) 2 2
I (4) 2 (4) 2 Trip Function Reactor Low low Water Level High Drywall Pressure (2), (3)
Reactor LON Pressure Containment Spray lnter-loc~ 213 Core Height Containment High.
Pressure Timer Auto Blowc!ONn low Pressure Core-Cooling Pump Discharge Pressure (fable cont'd next page) r:~-=~
\\.,, __,.--'*
8804110086 985~37 PDR ADOCK 0 DCD p
Trip level Setting 84" (plus 4, minus 0 Inches) above top of active fuel (5) less than or equal to 2 PSIG Greater than or equal to 300 PSIG & less than or equa I to 350 PSIG Greater than or equal to 2/3 core height Greater than or equal to 0.5 PSIG & less than or equa I *to 1.5 PSIG Less than or equal to 120 seconds Greater than or equal to 50 PSIG & less than or equal to 100 PSIG 3/4.2-10 I. In conjunction with low reactor pressure in It I ates core spray and LPC 1.*
- 2. In conjunction with high drywall pressure, 120 sec. time delay, and low pressure core cooling interlock Initiates auto blowdown.
4 *. Initiates starting of diesel generators.
I. Initiates core spray, LPCI, HPCI, and SBGTS.
- 2. In conjunction with low low water level, 120 sec. time delay and low pressure core cool Ing Interlock Initiates auto blowdown.
- 3. Initiates starting of diesel generators.
I. Permissive for opening core spray and LPCI actnission valves.
- 2. In conjunction with low low reactor water level Initiates core spray and LPCI.
Prevents inadvertent operation of containment spray during accident conditions.
Prevents Inadvertent operation of containment spray during accident conditions.
In conjunction with low low reactor water level, high drywall pressure and low pressure core cooling interlock initiates auto blowc!ONn:
- Defers APR actuation pending confirmation of low pressure core cooling system operation.
TABLE 3.2.2 (cont'd)
DRESDEN II DPR-19 Amenctnent No. ~
~. ~-
INSTRUMENTATION THAT INITIATES OR CONTROLS THE CORE AND CONTAINMENT COOLl_NG SYSTEMS Min. No. of Operable Inst.
Channe Is per.
Trip System CI)
Trip Function Trip Level Setting
(.
v 2/Bus C6) 2 2/Bus (6)
.4 KV Emergency Buses Loss of Voltage Sustained High Reactor Pressure Degraded Voltage on 4 KV Emergency Buses Trip on 2930 volts plus or minus 51 decreasing voltage tess than or equal to 1070 PSIG for 15 seconds Greater than or equal to 3708 VO I ts (equals 3784 volts less 21 tolerance) after less than or equal to 5 minutes (plus 51 tolerance) with a 7 second (plus or minus 20ll inherent time delay TABLE 3.2.2 CNotes)
I. Initiates starting of diesel generators.
- 2. Removes nonessential loads fran buses.
- 3. Trips emergency bus normal feed breakers.
Initiates Isolation condenser.
Initiates alarm and picks up time delay relay. Diesel generator picks up load If degraded voltage not corrected after time delay.
I. For al I positions of the Reactor Mode Selector Switch whenever any ECCS subsystem is required to be operable, there shall be _two operable or tripped trip systems.
If the first column cannot be met for one of the trip systems, that system shal I be tripped.
If the first column cannot be me-:V-for both trip systems, inmediately initiate an orderly shutdown to cold conditions.
- 2.
Need not be operable when primary containment integrity is not required.
- 3.
May be bypassed when necessary during purging for containment lnerting or deinerting.
- 4.
If an instrument is inoperable, it shal i' be placed (or simulated) in the tripped condition so that it will not prevent containment spray.
- 5.
Top of active fuel is defined as 360" above vessel zero for all water levels used In the LOCA analyses.
(See design Bases 3.2)
- 6.
In I ieu of note I; if either of the two relays in the trip system are inoperable, the associated emergency power source is inoperable and Limiting Condition *for Operation 3.9.B appl les.
- AP.R =Automatic Pressure Relief
- ~-*
3/4.2-11
DRESDEN II DPR-19 Amendment*No. 82, 83, 90 3.2 LIMITING CONDITION FOR OPERATION BASES (Cont'd.)
For effective emergency core cooling for small pipe breaks, the HPCI systetn must function since reactor pressure does not decrease rapidly enough to allow either core spray or LPCI to operate in time.
The automatic pressure relief function is provided as a backup to the HPCI in the event the HPCI does not operate.
The arrangement of the tripping contacts is such as to provide this function when necessary and minimize spurious operation.
The trip settings given in the specification are adequate to assure the above criteria are met (Ref. SAR Section 6.2.6.3).
The specification preserves the effectiveness of the system during periods of maintenance, testing or calibration and also minimizes the risk of inadvertent operation; i.e., only one instrument channel out of service.
Two radiation monitors are provided on the refueling floor which initiate isolation of the reactor building and operation of the standby gas treatment systems.
The trip logic is one out of two.
Trip settings of less than or equal to 100 mR/hr for the monitors on the refueling floor are based upon initiating normal ventilation isolation and standby gas treatment system operation so that none of the activity released during the refueling accident leaves the reactor building via the normal ventilation stack but that all the activity is processed by the standby gas.treatment system.
The instrumentatiop which is provided to monitor the post accident condition is listed in Table 3. 2. 6. '* The instrumentation listed and the limiting conditions for operation on,these* s)*stems *ensure adequate monitoring of the containment following a loss-of-coolant accident.
Information from this instrumentation will provide the operator with a detailed knowledge of the conditions resulting froll).the accident.. Bas~d on this information'he can make logical decision.s regarding post accident recovery.
The specifications allow for post accident instrumentation to be out of service for a period of 30 days. *This,period is based on the fact that several diverse instruments are available for guiding the operator should an accident occur, on the low probability of an instrument being out of service and an accident occurring in the 30-day period, and on engineering judgement.*
The radioactive liquid and gaseous effluent instrumentation is provided to monitor the release of radioactive materials in liquid and gaseous effluents during releases.
The alarm setpoints for the instruments are provided to ensure that the alarms will occur prior to exceeding the limits of 10 CFR 20.
The relay setting for 4I<V emergency bus loss of voltage is chosen to give positive indication of the need to start the diesel generator, without being affected by normal voltage fluctuations due to pumps starting.
Reset of the relay, approximately 11% above the trip point, indicates that the diesel generator has restored bus vol tag*e and will accept ECCS loads.
The reset signal provides a permissive for starting ECCS pumps.
The setting for 4I<V emergency bus degraded voltage is chosen to detect sustained degraded voltage which may cause equipment damage, while preventing trips caused by voltage fluctuations.
The reset point for degraded voltage indicates restoration of normal bus voltage.
B 3/4.2-33
DRESDEN Ill
,./
OPR-2~
Amenanent No._,n,.)1'.,;;<J TABLE 3.2.2 INSTRUMENTATION THAT INITIATES OR CONTROLS THE CORE ANO CONTAINMENT COOLING SYSTEMS Min. No. of Operable Inst.
Channels per Trip System (I) 2 2
I (4)
- 2 (4) 2
!.!:.l2.. Functl on Reactor Low Low Water Level High Drywall Pressure (2) j
(})
Reactor Low Pressure Containment Spray Inter-lock 2/} Core Height Containment High Pressure Timer Auto Slowdown Low Pressure Core Cooling Pump Discharge Pressure (Table cont'd next_ page)
Trip Level Setting B4" (plus 4, minus 0 inches) above top of active fuel (5)
Less than or equal to 2 PSIG Greater than or equal to }00 PSIG & less than or equal to 350 PSIG Greater than or equal to 2/} core height Greater than or equal to 0.5 PSIG & less than or equal to 1.5 PSIG.
Less tha~ or equal to 120 seconds Greater than or equal to 50 PSIG & less than or equal to 100 PSIG
}/4.2-10 I. In conjunction with low reactor pressure initiates core spray and LPCI.
- 2. In conjunction with high drywall pressure, 120 sec. time delay, and low pressure core cooling Interlock initiates auto blowdown.
- 4. Initiates starting of diesel generators.
I. Initiates core* spray, LPCI, HPCI, and SBGTS.
- 2. In conjunction with low low water level, 120 sec. time delay and low pressure core cooJing interlock Initiates auto blowdown.
}. Initiates starting of diesel generators.
I. Permissive for opening core spray and LPCI admission valves.
- 2. In conjunction with low low reactor water level initiates core spray and LPCI.
Prevents Inadvertent.operation*
of containment spray during accident conditions.
Prevents inadvertent operation of containment spray during accident conditions.
In conjunction with low low reactor water level, high drywall pressure and low pressure core cooling Interlock Initiates auto blowdown.
- Defers APR actuation pen~lng confirmation of low pressure core cooling system operation.
1
DRESDEN I I I
.J DPR-S5 Amenanent No. /7* )1, JJO TABLE l.2.2 (cont'd)
INSTRUMENTATION THAT INITIATES OR CONTROLS THE CORE AND CONTAINMENT COOLING SYSTEMS Min. No. of Operable Inst.
Channels per Trip System Cll 2/Bus C6l 2-2/Bus (6)
Trip Function 4 KV Emergency Buses los.s of Voltage Sustained High Reactor Pressure Degraded Voltage on 4 KV Emergency Buses Trip level Setting Trip on 29:50 volts plus or minus 51 decreasing voltage less than or equal to 1070 PSIG for 15 seconds Greater than or equal to l708 vo I ts (equals }784 volts less 2S tolerance) after less than or equal to 5 minutes (plus 51 tolerance) with a 7 second (plus or minus 20Sl inherent time delay TABLE l.2.2 (Notes)
I. Initiates starting of diesel generators.
- 2. Removes nonessential loads from buses.
- l. Trips emergency bus normal feed breakers.
Initiates isolation condenser.
Initiates alarm and picks up time delay relay. Diesel generator picks up load if degraded voltage not corrected after time delay.
I.
For al I positions of the Reactor Mode Selector Switch whenever any ECCS subsystem is required to be operable, there shall be tWo operable or tripped trip systems.
If the first colwnn cannot be met for one of the trip systems, that system shall be tripped.
If the first colwnn canno'fbe met for both trip systems, inmediately initiate an orderly shutdown to cold conditions.
~-
- 2.
Need not be operable when primary containment integrity is not required.
- l.
May be bypassed when necessary during purging for conta i 'nment inert i ng or deinertlng.
- 4.
If an instrument is inoperable, it shal I be placed (or simulated) in the tripped condition so that it will not prevent containment spray.
- 5.
- 6.
Top of active fuel is defined as }60" above vessel zero for all water levels used in the LOCA analyses.
(See design Bases l.2)
In lieu of note I, if either of the two relays In the trip system are Inoperable, the associated emergency power source Is inoperab!e and limiting Condition for Operation l.9.B applies.
- APR= Autanatlc Pressure Relief 3/4. 2-11 I
I
\\.
3.2.
DRESDEN III DPR-25 Amendment No. )If, yf, p.{
LIMITING CONDITION FOR OPERATION BASES (Cont'd.)
For effective emergency core cooling for small pipe breaks, the HPCI system must function since reactor pressure does not decrease rapidly enough to allow either core spray or LPCI to operate in time.
The automatic pressure relief function is provided as a backup to the HPCI in the event the HPCI does not operate.
The arrangement of the tripping contacts is such as to provide this function when necessary and minimize spurious operation.
The trip settings,given in the specification are adequate to assure the above criteria are met (Ref. SAR Section 6.2.6.3).
The specification preserves the effectiveness of the system during periods of maintenance, testing or calibration and also minimizes the risk of inadvertent operation; i.e., only one instrument channel out of service.
Two radiation monitors are provided on the refueling floor which initiate isolation of the reactor building and operation of the standby gas treatment.
systems.
The trip logic is one out of two.
Trip settings of less than or equal to 100 mR/hr for the monitors on the refueling floor are based upon initiating normal ventilation isolation and standby gas treatment system operation so that none of the activity released during the refueling accident leaves the reactor building via the normal ventilation stack but that all the activity is processed by the standby gas treatment system.
The-instrumentation which is provided to.monitor the post accident condition is listed in Table 3.2.6.
The instrumentation listed and the limiting conditions for operation on these systems ensure adequate monitoring of the containment following a loss-of-coolant accident.
Information from this instrumentation will provide the operator with a detailed. knowledge of the conditions resulting from the accident.
Based on this information he can make logical decisions regarding post accident recovery.
The specifications allow for post accident instrumentation to be out of service for a period of 30 days.
This period is based on the fact that several diverse instruments are available for guiding the operator should an accident occur, on tpe low probability of an instrument being out of service and an accident occurring in the 30-day period, and on.engineering judgement.
The radioactive !~quid and gaseous. effluent instrumentation is provided to monitor the release of radioactive materials in liquid and gasequs effluents during releases.
The alarm setpoints for the instruments are provided to ensure that the alarms will occur *Prior to exceeding the limits of 10 CFR 20.*
The relay setting for 4KV emergency bus ioss* of voltage is chosen to give positive indication of the need to start the diesel generator, without being affected by rormal voltage fluctuations due to pumps starting.
Reset of the relay, approximately113 above the trip point:, *indicates that the diesel generator has restored bus voltage and will accept ECCS loads.
The reset signal provides a permissive for starting Ec'cs pumps.
The setting for 4KV emergency bus degraded voltage is chosen to detect sustained degraded voltage which may cause equipment damage, while preventing trips caused by voltage fluctuations.
The reset point for degraded voltage indicates restoration of normal bus voltage.
B 3/4.2-33
ATTACHMBNT 3 SIGNIFICANT HAZARDS EVALUATION commonwealth Edison proposes to amend Licenses DPR-19 and DPR-25 to correct an inconsistency between the Technical Specification specified Trip Level Setting for emergency bus undervoltage relays and the actual relay settings.
BASIS FOR PROPOSED NO SIGNIFICANT HAZARDS CONSIDERATION DETERMINATION Commonwealth Edison has evaluated the proposed Technical specification changes and determined that they do not represent a significant hazards consideration.
Based on the criteria for defining a significant hazard established in 10 CFR 50.92(c), operation of Dresden Units 2 and 3 in accordance with the proposed changes will not:
a)
Involve a significant increase in the probability or consequences of an accident previously evaluated, for the reasons discussed below.
b)
The FSAR design basis of this "first level" undervoltage relay is to sense a loss of offsite power.
Upon sensing a loss of power to the 4KV bus, the non-essential loads are tripped, the emergency bus normal feed breakers are tripped and the diesel generator is auto started.
Upon restoration of bus voltage by the diesel generator, the ECCS pumps are allowed to restart.
Based upon the actual relay setting (i.e trip at 2930 +/-5\\ with reset at 3255 +/-5\\) and the applicable design basis for the diesel generator which states "Each diesel generator system is designed to st_art automatically within 10 seconds and accept full load within 30* seconds, upon loss of all normal sources of power" (FSAR 8.2.3.1)_, there':will be no effect upon loading sequence.
The reiay setting of 2930 wi.th a +/-5\\ tolerance is consistent with the manufacturer's spe~lfication. Therefore emergency systems will perform as described in the FSAR arig hence no change in probabilities or con~equences are involved.
Create the possibility of a: new or* different kind of ac.cident from any accident previously evaluated,, for th~ re~S<;?ni? discussed below.
The proposed Technical Spec;ification setpq_int for :.the.undervol tage relays does not affect -'the.'.function of the" relay *:to 'provide for detection of loss of offsite power and the-initiation of the emergency power source.
Since the existing setpoint of the undervoltage relay is unchanged and the fact that the setting meets the design basis for 1st level undervoltage protection, no new or different kind of accident is being created.
\\
3 -
c)
Involve a significant reduction in a margin of safety because:
4418K The actual as-set and proposed relay setting is unchanged.
Since that setting meets the design basis to provide detection of a loss of voltage condition and initiates an emergency power supply, the margin of.safety is unchanged.