ML19338G050
| ML19338G050 | |
| Person / Time | |
|---|---|
| Site: | Cooper  |
| Issue date: | 10/21/1980 |
| From: | NEBRASKA PUBLIC POWER DISTRICT |
| To: | |
| Shared Package | |
| ML19338G029 | List: |
| References | |
| TAC-42227, TAC-47003, TAC-47004, NUDOCS 8010280380 | |
| Download: ML19338G050 (7) | |
Text
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LIMITING CONDITIONS FOR OPERATION SURVEILLANCE REOUIREMENTS 4.3.C (Cont'd.)
3.3.C (Cont'd.)
i 3.
The maximum scram insertion time for 90% insertion of any operable control rod shall not exceed 7.00 seconds.
D.
Reactivity Anomalies D.
Reactivity Anomalies At a specific steady state base condi-During the startup test program and tion of the reactor actual control rod startup following refueling outages, the critical rod configurations will inventory will be periodically com-be compared to the expected configura-pared to a normalized computer pre-diction of the inventory.
If the ti ns at selected operating conditions, difference between observed and pre-These comparisons will be used as base data for reactivity monitoring during dicted rod inventory reaches the subsequent power operation through-equivalent of 1% Ak reactivity, the reactor will be shut dowr. until the ut the fuel cycle. At specific power perating conditions, the critical rod cause has been determined and correc-configuration will be compared to the tive actions have been taken as configuration expected based upon ap-appropriate, propriately corrected past data.
Yhis E.
Recirculation Pumps comparison will be made at least every full power month.
A recirculation pump shall not be started while the reactor is in natural circulation flow and reactor power is greater than 1% of rated thermal power.
F.
If Specifications 3.3.A through D above cannot be met, an orderly shutdown shall be initiated and the reactor shall be in the Shutdown condition within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
G.
The scram discharge volume (SDV) vent and drain valves shall be cycled and verified _open at least once every 31 days and prior to reactor start-up.
2.
The SDV vent and drain valves shall be verified to close within 30 sec-onds after receipt of a signal for control rod scram once per refueling cycle.
3.
SDV vent and drain valve operabil-ity shall be verified following any maintenance or modification to any portion (electrical or mechan-ical) of the SDV which may affect i
the operation of the vent and drain valves.
8@0280 j g o
_93_.
3.3 and 4.3 BASES:
(Cont'd)
The occurrence of scram times within the limits, but significantly longer than the average, should be viewed as an indication of a systematic problem with control rod drives.
In the analytical treatment of the transients, 290 milliseconds are allowed between a neutron sensor reaching the scram point and start of motion of the control rods.
This is adequate and conservative when compared to the typical time delay of about 1.J milliseconds estimated from scram test results.
Approximately the first 90 milliseconds of each of these time intervals result from the sensor and circuit delays; at this point, the pilot scram solenoid deenergizes.
Approximately 120 milliseconds later, the control rod motion is estimated to actually begin.
However, 200 milliseconds is conservatively assumed for this time interval in the transient analyses and this is also included in the allowable scram insertion times of Specification 3.3.C.
The time to deenergize the pilot valve scram solenoid is measured during the calibration tests required by Spec 4.1.
D.
Reactivity Anomalies During each fuel cycle excess operative reactivity varies as fuel depletes and as any burnable poison in supplementary control is burned.
The magni-tude of this excess reactivity may be inferred from the critical rod con-figuration. As fuel burnup progresses, anomalous behavior in the excess reactivity may be detected by comparison of the critical rod pattern at selected base states to the predicted rod inventory at that state. Power operating base conditions provide the most sensitive and directly inter-pretable data relative to core reactivity.
Furthermore, using power operating base conditions permits frequent reactivity comparisons.
Requiring a reactivity comparison at the specified frequency assures that a comparison will be made before the core reactivity change exceeds 1% Ak.
Deviations in core reactivity greater than 1% Ak are not expected and require thorough evaluation. One percent reactivity limit is con-sidered safe since an insertion of the reactivity into the core would not lead to transie'nts exceeding design conditions of the reactor system.
E.
Recirculation Pumps Until analyses are submitted for review and approval by the NRC which prove that recirculation pump startup from natural circulation does not cause a reactivity insertion transient in excess of the most severe coolant flow increase currently analyzed, Specification 3.3.E prevents starcing recirculation pumps while the reactor is in natural circulation above 1%
of rated thermal power.
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3.3 and 6.3,jf q:
(Cont'd)-
G.
To ensure the Scram Discharge Volume (SDV) does not fill with water, the vent and drain valves shall be verified open at least once every 31 days.
This.is to preclude establishing a water inventory, which if sufficiently large, could result in slow scram times or only a partial control rod insertion.-
The vent and drain valves shut on a scram signal thus providing a contained volume (SDV) capable of receiving the full volume of water discharged by the control rod drives at any reactor vessel pressure.
Following a scram the SDV is discharged into the reactor building
. drain system.
REFERENCES 1.
NEDO-10527, " Rod Drop Accident Analysis for Large Boiling Water Reactors," Paone, Stirn & Woolley, 3-72, Class I.
2.
NEDO-10427, Supplement 1,." Rod Drop Accident Analysis for Large Boiling Water Reactors," Stirn, Paone & Yound, 7-72, Class I.
3.
" Supplemental Reload Licensing Submittal for Cooper Nuclear Station Unit 1,"
(most current approved submittal).
l l
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h 1
TABLE 3.2.C CONTROL ROD WITilDRAWAL BLOCK INSTRUMENTATION Minimum Number Of Function' Trip Level Setting Operable Instrument Channels / Trip System (5)
'APIOi Upscale (Startup)
_< (0.66W + 42%) FRP (2) 2(1)
APRM Upscale (Flow Bias)
_ 12%
MFLPD 2(1)
APRM Downscale (9)
> 2.5%
2(1) e APRM Inoperative (10b) 2(1)
._ (0.66W + 41%) (2) 1
-RBM Upscale.(Flow Bias)'
RBM Downscale (9) 1 2.5%
1 RBM Inoperative (10c) 1 IRM Upscale (8)
< 108/125 of Full Scale 3(1) m T' - IRM Downscale (3)(8) 1 2.5%
3(1) 4 i
IRM Detector Not Full In (8) 3(1) 1RM Inoperative (8)
(10a) 3(1) 1 5
_ 1 x 10 Counts /Second 1(1)(6) l SRM Upscale'(8)
SRM Detector Not Full In (4)(8)
(> 100 cps) 1(1)(6)
Slot Inoperative- (8)
(10a) 1(1)(6)
_ 10% Difference In Recire. Flows 1
Flow Bia:) Comparator Flow Bias Upscale /Inop.
_ 110% Recire. Flow 1
SRM Downscale (8) (7)
> 3 Counts /Second (11) 1(1)(6)
_ 18 gallons 1(12)
{
SDV Water Level liigh i
i 1
11.
During spiral unloading / reloading, the SRM count rate will be below 3 cps for some period of time.
See Specification 3.10.B.
12.
With the number of OPERABLE channels less than required by the Minimum Number of Operable Instrument Channels / Trip System requirements, place the inoperable channel in the tripped condition within one hour.
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~
s TABLE 4.2.C SURVEILLANCE REQUIREMENTS FOR ROD WITilDRAWAL BLOCK INSTRUMENTATION Functional Function Test Freq.
Calibration Freq.
Instrument Check APRM Upscale (Flow Blas)
(1)
(3)
Once/3 Months once/ Day APRM Upscale (Startup Mode)
(1)
(3)
Once/3 Months once/ Day APRM Downscale (1)
(3)
Once/3 Months once/ Day APIGi Inoperative.
(1)
(3)
N.A.
Once/ Day RBM Upscale (Flow Bias)
(1)
(3)
Once/6 Months Once/ Day RBM Downscale (1)
(3)
Once/6 Months Once/ Day RBM Inoperative (1)
(3)
N.A.
Once/ Day IRM Upscale (1)
(2)
(3)
Once/3 Months once/ Day IRM Downscale (1)
(2)
(3)
Once/3 Months once/ Day IRM Detector Not Full In (2)
(Once/oper.
Once/Oper. Cycle (10)
Once/ Day
,y ating cycle) i 1101 Inoperative (1)
(2)
(3)
N.A.
N.A.
SRM Upscale (1)
(2)
(3)
Once/3 Months once/ Day SRM Downscale (1)
(2)
(3)
Once/3 Months Once/ Day 1
~ Siel Detector Not Full In (2)
(Once/oper-Once/Oper. Cycle (10)
N.A.
ating cycle)
Slut Inoperative (1)
(2)
(3)
N.A.
N.A.
Flow Blas Comparator (1)
(8)
Once/Oper. Cycle N.A.
Flow Bias Upscale (1)
(8)
Once/3 Months N.A.
l Rod Block Logic (9)
N.A.
N.A.
RSCS Rod Group.C Bypass (1)
(11)
Once/3 Months N.A.
1 SDV liigh Water Level Quarterly Once/Oper. Cycle N.A.
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4 i
3.2 BASES (cont'd.)
prevention of critical heat flux in a local region of the core, for a single rod withdrawal error from a limiting control rod pattern.
The IRM rod block function provides local as well as gross core protection.
The scaling arrangement is such that trip setting is less than a factor of 10 above the indicated level.
A downscale indication on an APRM or IRM is an indication the instrument has failed or the instrument is not sensitive enough.
In either case the instrument will not respond to changes in control rod motion and thus, control rod motion is prevented.
The downscale trips are set at 2.5 indicated on scale.
The flow comparator and scram discharge volume high leval components have only one logic channel and are not required for safety.
The SDV high level rod block does provide adequate time to determine the cause of the level increase and take corrective action prior to automatic scram.
The refueling interlocks also operate one logic channel, and are required for a safety only when the mode switch is in the refueling position.
The effective emergency core cooling for small pipe breaks, the HPCI system, must function since reactor pressure does not decrease rapid 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.
The specification preserves the effectiveness of the system during periods of maintenance, testing, or calibration, and also minimizes the risk of inadver-tent operation; i.e.,
only one instrument channel out of service.
Two air ejector off-gas monitors are provided and when their trip point is reached, cause an isolation of the air ejector off-gas line.
Isolation is initiated when both instruments reach their high trip point or one has an upscale trip and the ott sr - downscale trip.
There is a fifteen minute delay accounted for by the 30-minute holdup time of the off-gas before it is reached to the stack.
Both instruments are required for trip but the instruments are so designed that any instrument failure gives a dosnscale trip.
The. trip setting of 1.0 ci/sec (prior to 30 min. delay) provides an improved capability to detect fuel pin cladding failures to allow prevention of serious degradation of fuel pin cladding integrity which might result from plant operation with a misoriented or misloaded fuel assembly.
This limit is more restrictive than 0.39 ci/sec noble gas release rate at the air ejectors (af ter 30 min. delay) which was used as the source term for an accident analysis of the augmented off-gas system.
Using the.39 ci/sec source term, the maximum off-site total body dose would be less than the.5 rem limit.
Two radiation monitors are provided which initiate the Reactor Building Isolation function and operation of the standby gas treatment system. The trip is actuated by one hi-hi or two downscale indications.