ML20002C496
| ML20002C496 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 03/10/1975 |
| From: | CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | |
| Shared Package | |
| ML20002C471 | List: |
| References | |
| NUDOCS 8101100373 | |
| Download: ML20002C496 (8) | |
Text
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Limiting Conditions for Operation Surveillance Requirerent 3.1 5 REACTOR DEPRESSURIZATION SYSTEM h.l.5 REACTOR DEPRESSURIZATION SYSTEM Applicability:
Applicability:
Applies to the operating status of the Reactor Applies to periodic testing requirements for I
Depressurization System (RDS).
the RDS.
Objective:
Objective:
To assure the operability of the RDS and when To verify operability of the RDS.
vorking in conjunction with the emergency core cooling system to ellow cooling of the reactor Specification:
fuel in the event of a Loss of Coolant Accident.
00 A.
The isolation valves shall be test-operated CD Specification:
at least once every three months per Sec-tion IWV-3410 Summer 1973 Addenda of the y(
A.
The RDS shall be operable at all power ASME BkPV Code Section XI.
cp levels (ie, whenever the reactor is criti-p cal with the head on) except as specified B.
The depressurizing valves shall be test-
,,jg in 3.1 5.B, D, E, F and G below.
operated during each cold shutdown; how-ever, in the case of frequent cold shut-C#O B.
Should one depressurizing valve or isola-downs, these valves need not be exercised tion valve become inoperable in the closed more often than once every three months per position, the reactor may remain in opera-Section IWV-3410 Su=mer 1973 Addenda of the tion for a period not to exceed seven (T)
days provided the remaining depressurizing valves and isolation valves are determined C.
When it is determined that one of the RDS to be operable and they are test-operate"s valves (depressurization or isolation as described in Specification h.1.5.C.
valves) is inoperable in the closed posi-tion, the remaining valves shall be demon-If the inoperable valve cannot be returned strated to be operable immediately.
to service within seven (T) days, the reactor shall be shut down.
Rev B, 2/2h/75
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Limiting Conditions for Operation Surveillance Requirement 315 REACTOR DEPRESSURIZATION SYSTEM (Contd) 4.1 5 REACTOR DEPRESSURIZATION SYSTEM (Contd)
Should one isolation valve or depressuri-D.
The instrumentation shall be functionally zing valve become inoperable in the open tested, calibrated and checked as indi-position, during power operation, the cated in Table k.5 2.h.
System Logic plant will be brought to the cold shutdown shall also be functionally tested as condition within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.
indicated in Table 4.5 2.h.
C.
The limiting conditions for operation of E.
Should one input channel fail, the the instrumentation which initiates and remaining three channels shall be tested controls the RDS are given in Table immediately.
3 5 2.h.
F.
Should one output channel fail, the D.
Should one input channel fail, the re-remaining channels shall be tested actor may ramain in operation for a period immediately.
not to exceed seven (7) days provided the remaining input channels are determined G.
The cell voltage and specific gravity to be operable as described in Specifica-of each cell of the UPS will be deter-tion 4.1 5.E.
If the failed channel mined on a monthly basis.
cannot be returned to service within seven (7) days, the reactor shall be H.
The RDS containment penetration assen-l shut down.
blies seal pressure shall be examined at six-month intervals.
E.
Should one output channel fail, the re-actor may remain in operation for a period not to exceed seven (7) days pro-vided the remaining output channels are determined to be operable as described in Specification h.1 5.F.
If the failed channel cannot be returncd to service within seven (7) days, the reactor shall be shut down.
F.
The four uninterruptible power supplies (UPS) shall be operable at all power 4
Rev B, 2/24/75
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Limiting Conditions for Operation Surveillance Reguirement 315 REACTOR DEPRESSURIZATION SYSTEM (Contd) h.l.5 REACTOR DEPRESSURIZATION SYSTEM (Contd) levels (ie, whenever the reactor is criti-cal with the head on). Should one of four divisions of the UPS become inoperable, the 1
reactor may remain in operation for a period not to exceed seven (7) days provided the associated equipment of the three remaining UPS is determined to be operable and it is t
test-operated periodically as described in Specifications 4.1 5.C, E and F.
G.
Should the RDS containment penetration seal pressure be lost and it is determined that the electrical conductor seal (s) are leaking in excess of the leakage allowable as described in Specifications 3 3.1 and h.3.1 and the seal pressure cannot be re-stored within a 2h-hour period, the reactor shall be shut down.
Bases:
The RDS provides for both manual and automatic depressurization of the primary system to allow injection of the core spray fbilowing a small-to-intermediate size break in the primary system. This will allow core cooling with the objective of preventing excessive fuel clad temperatures. The design of this system is based on the specified initiation set points described in Table 3.5 2.h.
Transient analyses reported in Section 6 of the RDS Descrip-tion, Operation and Perfbrmance Analysis submitted August 15, 1974 to the Directorat of Licensing USAEC, to demonstrate that these conditions result in adequate safety margins for both the fut_ and the system pressure.
Performance analysis of the RDS is considered only with respect to its depressurizing effect in conjunction with core spray. Therefbre, no credit is taken for steam cooling of the core which provides further conse:'vatism to the emergency core cooll'g system.
These specifications ensure the operability of the RDS under all conditions fbr which the automatic or manual depressurization of the system is an essential response to the transient described above.
Rev B, 2/2h/75
n Bases: (Contd)
One RDS valve can remain out of service in the closed position for seven days because of redundancy, provided the remaining RDS valves are test-operated immediately as described in Specification h.l.5.C.
When conditions for the actuation on the depressurizing system are reac'ned, all the valves in the four blowdown paths are opened. Each blowdown path is designed to pass 1h4 lb/second of steam at 1350 psig which is a third of the required total flow rate. Therefore, failure of one flow path to open upon actuation does not preclude achieving 1
the required rate of depressurization.
In addition to reactor protection instrumentation, which initiates a reactor scram, protective instrumentation has been provided for the RDS which initiates action to mitigate the consequences of the Loss of Coolant Acci-dent.
This set of specifications provides the limiting conditions of operation for the RDS.
The objectives of the specifications are (i) to assure the effectiveness of the protective instrumentation when required even during periods when portions of such systems are out of service for maintenance and (ii) to prescribe the trip settings required to assure adequate performance. To conduct the required input channel maintenance or func-tional tests and calibrations, any one channel may be bypassed.
If the input channel is not bypassed when functional tests and calibrations are performed, actual trip signals supersede test and calibration conditions.
The minimum functional testing frequency used in this specification is based on a frequency that has proven acceptable and conforms to that of the existing reactor protection system.
Four plant variables are monitored and used as inputs to the actuation system. These are (1) steam drum water level, (2) reactor water level, (3) motor-driven fire pump discharge pressure and (b) diesel engine driven fire pump discharge pressure. These variables are jointly processed b/ the four independent actuation system input channels which are physically and electrically isolated from one ancther. A failure in one channel cannot propa-gate into another channel. Each of the four p1snt variables is monitored by four separate sensors. One sensor in each of the four variables is associated with each of the four input channels. The actuation of the RDS is enabled when two of the four input channels are in a tripped state.
The input channel is in a tripped state upon coincidence and subsequent processing of the following inputs:
(1) Lov 3.iteam drum level (delayed for two minutes), (2) high fire pump discharge pressure (either diesel-or mator-driven) and (3) low reactor water level. A low steam drum level signal is generated when the steam drum level sensor associated with the input channel indicates a level of 25" below steam drum center line.
This low steam drum level signal initiates a two-minute delay which allows a containment evacuation interval prior to system blowdown and also pennits the incorporation of operator input to the system initiation logic specified in the design basis (Reference Section 3.3.D of the August 15, 1974 RDS Description, Operation and Rev B, 2/24/75
A
~
o Bases: (Contd)
Performance Analysis). For the latter, the operator is provided with manual timer reset capability for each of the four input channels at the control panel. The lov steam drum level signal is also used to generate a fire pump start signal. Verification of a fire pu=p start and thus verification that a source of core spray water is available at the core spray valves is obtained when the. pressure switch associated with the input channel at either fire pump discharge has tripped, corresponding to a pressure equal to or exceeding 100 psig.
This variable is used as an enabling input to the actuation system to prevent depressurizing the reactor coolant system when the source of coolant required to cool the core is not available. A low reactor water level signal is generated when the input channel reactor water level sensor indicates a level > 2'8" above the top of active fuel. Low reactor water level is confirmation of the LOCA and with the other two inputs present (time delayed low drum level and core spray water availability) causes the automatic trip of the input channel. These trip level settings were chosen to be lov enough to prevent spurious actuation but high enough to initiate EDS operation so that post-accident cooling can be accomplished.
Upon failure of an uninterruptible power supply (UPS) or a channel power supply, the affected channel fault con-dition is alarmed as " channel
'X' unavailable." Power failures associated with input channels cause the coin-cidence trip conditions for the input channels to change from 2-out-of-h to 2-out-of-3 The output channel actuation coincidence reverts to 3-of-3 upon failure of an output channel power supply.
Input channel bypass capability is provided to permit bypassing any one input channel at a time. The bypass feature is used to bypass a channel when the channel has failed to the " trip" state and/or when channel mainte-nance is required. Bypassing of an input channel in the " trip" state or for maintenance causes the coincidence trip condition of the input channel to be changed from 1-out-of-3 or 2-out-of-h, respectively, to 2-out-of-3 The input channel bypassed condition is alarmed as " channel 'X' unavailable" and " bypassed."
Should an output channel require maintenance or should a single fault cause an output channel subchannel trip (two independent subchannels operate in 2 of 2 coincidence), the output channel actuation capability can be disabled by removing the associated 125 V DC supply. The 125 V DC supply to an output channel is disabled via a circuit breaker in its respective UPS. The disabling of an output channel is alarmed as " channel
'X' unavailable."
Since 3-out-of-4 output channels are required to assure design requirements are met (one output channel operates one depressurizing valve and one 3 31ation valve), the failure of one output channel vill not preclude achieving the required rate of depressurir This redundancy also enables maintenance to be performed on one output channel while the plant is in oi 1.
i Rev B, 2/2h/75
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A.
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Bases: (Contd)
Once the RDS actuation system output channels are enabled (at least two input channels are in a tripped state or a manual trip is initiated) and tripped, they remain in that_ condition until they are manually reset. This reset can be accomplished only after the initiating signals (ie, input channel trips or manual trip) have been restored to levels at which RDS operation is not required.
Separate, independent and one-hour sources of electrical power are provided, through four divisions, to accom-plish the detection of the LOCA and the completion of the depressurization. Each of the divisions (1, 2, 3 and h) is supplied with electrical power from one of four independent uninterruptible power supplies (UPS) consisting m of a battery charger, a battery and an inverter.
Each UPS has output of 120 V AC, 60 Hz and 125 V DC.
Divisions 1 and 2 normally receive power from the existing h80 V AC Bus lA.
Divisions 3 and h are supplied by 480 V AC Bus 2A.
Normal station power to Busses lA and 2A can be provided by one of three sources:
(1) The station turbine generator, (2) the 138 kV transmission line or (3) the h6 kV transmission line. Should none of these sources be available, provision is included for sup-plying input power from the h80 V AC Bus 2B which is tied to the emergency diesel.
If all h80 V AC power is lost, the UPS is capable of sustaining its output for one hour.
Since only 3-out-of-h blowdown paths are required to assure adequate depressurization, the single system failure of one UPS division vill not preclude achieving the required rate of depressurization. This redundancy also enables maintenance to be performed on the UPS while the plant is in operation.
Four new containment penetration assemblies are used in transmitting electrical power, control and instrumenta-tion signals between equipment located inside the containment building and facilities located external to the containment building. These electrical penetrations are velded into spare containment penetration sleeves. The penetration assemblies are designed in accordance with IEEE 317 and are seismically and environmentally quali-fled to the RDS design conditions.
r The pressure retaining portion of the assemblies is designed and fabricated to the requirements of Subsection I
NE, Class MC vessels, of Section III of the ASSE Code. The penetration assemblies include a single aperture seal and a double electrical conductor seal and are designed to operate with the internal cavity pressurized with nitrogen at approximately 27 psig. The relatively maintenance-free seal assemblies dictate a mini =um inspection frequency of twice annually.
Rev B, 2/2h/75
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Tables 3.5.2.h and h.5 2.h Instrumentation That Initiates RDS Operation 3 5.2.H - Limiting Conditions for Operation h.c.2.H - Surveillance Requirement Minimum Prt>tective Operable Conditions for Instrument Instrument Channel Parameter Channels Limiting Set Point Operability Trip Test Calibration Trip
-Low Steam Drum 3
Above or Equal to At Power Levels Monthly Each Major Level 25" Below Center Whenever the Refueling Line Reactor Is Critical With the Head On Fire Pump (s) 3
> 100 Psig Ditto Monthly Ditto Discharge Pressure Low Reactor 3
2.2'8" Above Top Monthly Water Level of Active Fuel 120-Second 3
1 120 Seconds Fol-Monthly Time Delay loving Low Steam Drum Level Signal Input Channels 3
Monthly A Through D Monthly Output Channels 3
I Through IV Monthly
' Fire Pump Start 1
Monthly
- Reference Specifications 3.1.h and h.l.h for Bases.
J Rev B, 2/2h/75
NRC L.aTRIBUTIOh! FOR PART 50 DOCKE
.c1 ATE RI AL (TEMPORARY FORM)
CONTROL NO:3 7.3 8 FILE:
FROM: consumers r wer company DATE OF DOC DATE REC'D LTR TWX RPT OTHER Jackson, M1 :higan 49201 3-10-75 3-12-75 XXX R A Lamlev TO:
ORIG CC OTHER SENT AEC PDR XX DL 3 signed SENT LOCAL PDR XX CLASS UNCLASS PROPINFO INPUT NO CYS REC'D DOCKET NO:
XXXXXX XXXXXXXX 3
50-155 DESCRIPTION:
ENCLOSURES:
Ltr re their 8-15-74 submittal...........
hadt to OL/ Change to Tech Specs: consis tin;;
notarized 3-10-75...trans the following:
of incorporation of their Reacteo Depresure-ization System Description, Operation & Per-formance Analysis reporting program........
(40 cys enc 1 rec'd)
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