ML20066F790
| ML20066F790 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 11/17/1982 |
| From: | OMAHA PUBLIC POWER DISTRICT |
| To: | |
| Shared Package | |
| ML20066F787 | List: |
| References | |
| NUDOCS 8211190180 | |
| Download: ML20066F790 (15) | |
Text
F 2.0 LIMITIMG CONDITIONS FOR OPER/ TION 2.10 Reactor Core (Continued) 2.10.3 In-Core Instrumentation Applicability Applies to the operability and alarm values of the rhodium detector in-core instruments system.
Objective To specify the functional requirements on the use of the rhodium in-core instrumentation system for.(1) the recali-bration of the ex-core detector inputs to the axial power distribution trip calculators and (2) monitoring of kw/ft and power distribution.
Specification (1) A minimum of four in-core locations at each detector level (or a total of 16 detectors) with at least one location in the center seven rows of fuel assemblies and at least one location outside the center seven rows of feel assemblies shall be operable during recalibration of the ex-core detectors.
i (2) The in-core detector system shall be operable (an oper-able in-core detector string consists of three or more operable rhodium detec, tor,s) with either:
(a) A normal complement consisting of:
1.
At least 75% of all in-core detector strings operable, and 2.
A minimum of two operable in-core detector strings per full axial length ouadrant whenever the in-core system is used to monitor F T T
xy,
FR, the radial power distribution and the peak linear heat rate, or 1
(b) A reduced complement consisting of:
1.
At least 20% of all in-core detector strings operable, and 2.
A minimum of one operable in-core detector string per full axial length quadrant whenever the in-core detector system is used to T
T monitor Fxy, pR, the peak linear heat rate, and the radial power distribution, provided:
(i) The planar radial peaking factor uncer-tainty, Uxy, the integrated radial peaking i
8211190180 821118 factor uncertainty, U, and the total R
PDR ADOCK 05000285 P
PDR 2-54 Amendment No. 14, 32, 47 ATTACHMENT A i
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2.0 LIMITING CONDITIOHS FOR OPERATION 2.10 Reactor Core (Continued) 2.10.3 In-core Instrumentation (Continued) peaking factor uncertainty, U, are deter-o mined every 31 EFPD, in accordance with a cycle specific analysis performed in a manner as given in the reference.
(ii) If UR >.06 the value of F to be used in R
evaluating the approach to the limits of Specification 2.10.h(2) in:
M (1 + UR - 0.06)
FR=FR M
where FR is determined from a power distribution map with no part length CEA's inserted and all full length CEA's at or above the Long Term Steady State Insertion limit for the existing Reactor Coolant Pump combination, and the integrated radial peaking factor uncertainty, Up, is the latest determined value of UR at the M is determined.
time Fp (iii) If Uxy >.07 the calculated value of Fxy to be used in evaluating the approach to the limits of Specification 2.10.4(3) is:
Pxy *= Fxy* (1 *+ U e 0.C7) xy where F M is determined from a power xy distribution map with no part length CEA's inserted and all full length CEA's at or above the Long Term Steady State Insertion licit for the existing Reactor Coolant Pump combination and the planar radial peaking factor uncertainty, Uxy, is the l
latest determined value of U at the time xy F M is determined.
xy l
(iv) If Uq >.07 the total peaking factor uncertainty factor defined as (1 + U )
q shall be used in place of the measurement-calculation factor of 1.07 in Specifi-cation 2.10.h(1).
(v) The maximum local peak Jinear heat rate in the core, Omax, shall be determined and the incore detector alarms shall be ad-justed to no greater than the following:
Alarm Setting = C
- Callowed Omax 2-55 Amendment No. %K, 22, h7
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2.0 LIMITI!!O CO?IDITIONS FOR OPERATIOft 2.10 Reactor Core (Continued) 2.10.3 In-core Instrumentation (Continued) where:
C = The detector signal converted to flux units when the reactor is operating at steady-state.
Callowed = Linear heat rate (kv/ft) al-loved by Specification 2.10.h(1) and adj'sted as required by Specification 2.10.3(2)(b)(iv).
Omax = The maximum local peak linear heat rate (kv/ft) measured at the same reactor conditions as C above.
(3) If the in-core detector system is not operable within the interval specified, the peak linear heat rate shall be monitored by ex-core detectors per Specification 2.10.h(1)(c) and the surveillance requirements of Specification 3.10(5) are deleted.
(4) If the recalibration of the ex-core detectors has not been accomplished within the previous 30 equivalent full power days, reduce the axial power distribution monitor-ing li,mits,and,tr,1,p se,tpoints, Figures 2-6, 2-7, and 1-2, by 0.03 ASI units. If the recalibratlon of the ex-core detectors has not been accomplished within the previous 200 equivalent full power days, the power shall be limited to 3ess than that corresponding to 75% of the peak linear heat rate permitted by Specification 2.10.4.(1).
(5) After each fuel loading, the incore detector system shall be operable with at least 75% of the incore detector l
strings operable and a minimum of two quadrant symmetric incore detector string locations per core quadrant for the initial measurement of the linear heat rate, FR*
F T ond the azimuthal power tilt.
xy (a) An operable incore detector string shall consist of three operable rhodium detectors.
(b) A quadrant symmetric incore detector string location shall consist of a location with a symmetric counter-part in any other quadrant.
(c) The initia3 measurement of the linear heat rate, T
T R,p and azimuthal power tilt shall consist of Fthe fibt full core power distribution calculation based on incore detector signals made at a power level greater than h0 percent of rated power follow-ing each fuel loading.
l 2-55a i
2.0 LIMITING C0!TDITIONS FOR OPERATIOI!
2.10 Reactor Core (Continued) 2.10.3 In-Core Instrumentation (Continued)
If an init.ial measurement of the linear heat rate, FRe F T and asinuthal power tilt cannot be made with an xy operable incore detector system as defined above, reactor power shall be restricted to less than 75 percent of the peak e.11ovable heat rate.
Basis The in-ccre instrument system is used to monitor core per-formance and to insure operation within the limits used as initial conditions for the safety analysis in three ways:
T (1) to verify that the radial peaking factors (F and FR) arelessthanthelimitsspecifiedinSpecifbations 2.10.h(2) and 2.10.h(3),
(2) to actuate alarms set on each individual instrument to insure operation within specified kv/ft limits of Figure 2-5, and
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(3) to determine the axial shape index for periodic veri-fication of the calibration of the ex-core detector system.
The specification requires a minimum number of detectors and proper. distribution.to,.perf.orm these, functions.. In-core rhodium detectors in conjunction with analytical computer codes calculate power distributions from which F and FR are xy determined. Alarm limits are set on each in-core instrument to insure operation within specified kv/ft limits.
Operation of the in-ccre detector system for peak linear heat T with less rate monitoring and surveillance of Fp'T and F than757.ofthestringsoperablerequiresaddNionalmeasures to compensate for degradation of the in-core instrument sys-tem.
Periodic comparisons between calculated and measured l
power distributions are made to confirm the core is depleting
(
as designed. The measurement uncertainties are computed to l
assure the assumptions made in the setpoint analysis are valid. The uncertainties are computed using the methods given in the reference.
If the deterrined uncertainties exceed the e.ncertainties used in the setpoint and safety analysis, the measured values of FR and F are augmented by the appropriate uncertainty.
These j
newvaiuesofF and F x
withSpecificatkons2.b.arethenusedtoverifycomplitnce l
h(2) and 2.10.h(3). This assures l
l that the products of the radial peaking factors and their appropriate uncertainties are less than the values used in determining the setpoints.
2-55b l
e 2.0 LIMITING CONDITIONS FOR OPERATION 2.10 Reactor Core (Continued) 2.10.3 In-Core Instrumentation (Continued)
The minimum margin to the kw/ft limit is used to set alarms on all detectors.
This imposes restraint on the power distribu-tion as well as the peak linear heat rate and precludes the occurrence of undetected peaks larger than the limit. When in-core detector alarms are set using this method, several alarms would be received in the event of a shift in the power distribution even though the maximum Jocal peak linear heat rate may not be exceeded.
Calibration of the ex-core detector input to the APD calcu-lator is required to eliminate ASI uncertainties due.to in-strument drift and axially nonuniform detector exposure.
If the recalibration is not performed in the period specified, the prescribed steps will assure safe operation of the re-actor.
j Reference
.I INCA /CECOR Power Peaking Uncertainty -- CENPD-553-P, Revision i
1-P-A, May 1980.
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6.0 INTERIM SPECIAL TECllNICAL SPECIFICATIONS 6.4 Operation Gith Less Than 75% of Incore Detector Strings Operable DELETED 1
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Amendment No. 55 6-4 l
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6.0 INTERI!! SPECIAL TECllNICAL SPECIFICATIONS 6.4 Operation With Less Than 75% of Incore Detector Strings Operable (Continued)
DELETED i
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l Amendment No. 55 6-5 1
6.0 INTERIM SPECIAL TECllNIC E SPECIFICATIONS
_poption With Less Than 75% of Incore Tletector Strings Operable 6.5 O
(Continued)
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Amendment No. 55 6-6
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6.0 INTERIM SPECIAL TECHNICAL SPECIFICATIONS 6.4 Operation With Less Than 757, of Incore Detector Strings Operable (Continued) t i
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i Amendment No. 55 6-6 I
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Discussion The purpose of this change is to pennit operation with less.than 75% of the incore detector strings operable and to assess the uncer-tainty penalty which must be applied. Operation with less than 75% of the incore detector strings operable was justified for Cycle 6 in Interin Special Technical Sepcification 6.h.
The proposed amendment application incorporates the Cycle 6 interim specification into the main body of the Technical Specifications and stipulates that a cycle speci-fic analysis must be performed whenever L=plementation is required. The.
incorporation of this specification vill eliminate-the need for creating an interim specification during cycles when the 75% operability require-ment cannot be met.
Fort Calhoun Station's past experience with Cycle 6 detector failures and the current operability status of Cycle 7 through August 29, 1982, as shown in Figure 1, indicate that the accumulated failures generally should not reach the minimum cperability condition until mid-cycle or later, if at all. Minimum operability should not occur sooner, because all inoperable strings (i.e., two or more' fail'ed detectors) are replaced during each refueling outage, thus permitting beginning-of-cycle oper-ation with all strings operable.
The mid-cycle or later implementation of the alternate operating mode (i.e., 20 to 75% of the strings operable) corresponds to a burnup T and F T, vill have decreased to when the radial peaking factors, FR g
values low.enough in jnagnitude,.that svqn with, the appligation of ad-ditional uncertainties, sufficient margin to the Technical Specification limits vill exist. When implemented in Cycle 6, as an example, the R and F including a 1.01 multiplier vere 1.hh and untilted values of F 1.47 which are well below th Technical Specification limits of 1 52 and T and F T values, 1 57 Figures 2 and 3 show plots of the measured FR xy respectively, as a function of burnup for Cycle 7 At the August 26, T and F T vere 1.h5 and 1982 burnup of Th63 MWD /MTU, the values of FR xy 1.h8 which have large margins relative to their respective limits of 1 57 and 1.62.
l The methods used in deriving the edditional uncertainty (or penalty) i to be applied are documented in Reference (1) and are consistent with Reference (2).
Reference (3), a Jetter to the Nuclear Regulatory Com-mission, provides a copy of Reference (1)- and demonstrates the method xy, F, and FR remain j
used to ensure that the assumed uncertainties on,F q
within their calculated limits.
The Reactor Protection System setpoints remain valid with the proposed change.
The functions potentially affected include the kv/ft l
and departure from nuclear boiling (DNB), limiting conditions for operation (LCO's), and limiting safety system settings (LSSS's). Each l,
of these is addressed below.
T The maximum total unrodded radial peaking factor, Fxy, that can occur with the CEA's inserted above the power dependent transient in-sertion limit is factored into the ex-core kv/ft LCO.
Periodic monitor-ing of FxyT using the incore detector system is required to assure that 1
4 AI'fACHMENT B
- the F T assumptions used in the synthesis of the excore LCO are not exceekd. If F T exceeds the Technical Specification limit (Technical xy Specification Figure 2-9), the allowed power is reduced to a value for which the kw/ft LCO and LSSS is conservative.
For operation with a reduced complenent of incore detectors, the allowed limit for F T is penalizedbytheincreasedmeasurementuncertaintytomaintaint[e x
allowed power.
T The maximum integrated radial peaking factor, FR, that can occur with the CEA's inserted up to the power dependent transient insertion ligit is factored into the DNB LCO.
During the periodic monitoring of FR, using the incore detector system, the F T value must be within the R
allowed limits of Technical Specification Figure 2-9 to ensure that the T
assumptions used in the DNB LCO synthesis are valid.
If FR exceeds this figure's limit, the allowed power is penalized to a value for which the TM/LP trip and DNB LCO become conservative and valid. For operation T
with a reduced complement of incore detectors, the allowed limit of FR is penalized by the increased measurement uncertainty, maintaining the allowed power while still ensuring the validity of the-DNB LCO and TM/LP trip.
References 1.
" Analysis of CECOR Power Peaking Uncertainties for Fort Calhoun Unit 1 Cycle 6", Report CEN-150(0)-P, February 1981.
2.
" INCA /CECOR' Poser Pedking' Uticerthin*ty", RBport CENPD-153-P, Re-vision 1-P-A, May 1980.
3.
Letter from W. C. Jones to Charles M. Trammell, dated April 24, 1981.
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CALLED NORTH CYCL'E 7 OPERABLE INCORE DETECTOR STATUS Figure 1
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LEVEL 2 LEVEL 4 a Open square indicates failed detectors.
Figure 2 INTEGRATED RAD PEAKING vs BURNUP RAD PEAKING FACTOR FAT 1.60 W
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FEE JUSTIFICATION The proposed Facility l.icense Amendment is deemed to be a Class III Amenduent within the meaning of 10 CFR 170.22. This determination is made in that it involves only a single safety issue and does not involve a significant hazards consideration.
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