ML20034H078

Proposed TS Supporting Reduction of in-core Instrument Requirements

ML20034H078
Person / Time
Site:	Calvert Cliffs
Issue date:	03/09/1993
From:	BALTIMORE GAS & ELECTRIC CO.
To:
Shared Package
ML20034H077	List: ML20034H076 ML20034H078
References
NUDOCS 9303150215
Download: ML20034H078 (7)

Text

{{#Wiki_filter:. ATTACHMENT (2) i UNIT I i TECHNICAL SPECIFICATION REVISED PAGES i 3/42-2 i 3/42-6 3/4 2-11 1 3/4 3-31 k 1 f t i h i ? r r h Y k b o

H 3/4.l: POWER DISTRIE NION LIMITS - i j SURVEILLANCE REQUIREMENTS (Continued)

c. - Verifying at lea,t once per 31 days that the AXIAL SHAPE INDEX is maintained within the limits of Figure 3.2.1-2, where 100 percent i

of the allowable power represents the maximum THERMAL POWER i allowed by the following expression: l l MxN j where: [ } 1. M is the maximum allowable THERMAL POWER level for the j existing Reactor Coolant Ptnp combination. 2. N is the maximum allowable fraction of RATED THERMAL POWER I as determined by the P, curve of Figure 3.2.1-3. l 4.2.1.4 Incore Detector Monitorino System - The Incore Detector Monitoring l System may De used for monitoring the core power distribution by verifying that the incore detector Local Power Density alarms a. Are adjusted to satisfy the requirements of the core power _y_ distribution map which shall be updated at least once per 31 days a of accumulated operation in MODE 1. b. Have their'alann setpoint adjusted to less than or equal to the limits shown on Figure 3.2.1-1 when the following factors are .i appropriately included in the setting of these alarms: 1 A measurement-calculational uncertainty factor of 1.062,S4 l 1. 5 2. An engineering uncertainty factor of 1.03 -{ 3. A linear heat rate uncertainty factor of 1.002 due to axial i fuel densification and thennal expansion, and I i 4. A THERMAL P0k'ER measurement uncertainty factor of 1.02. l > CZDssar 8'1 i K V [ I /Y s c /? T d 1 i CALVERT CLIFFS - UNIT l' 3/4 2-2 Amendment No.-1 4 i l , a n1.t

3/4.2 POWER DISTRIBUTION LIMITS ( 3/4.2.2 TOTAL PLANAR RADIAL PEAKING FACTOR - FI, LIMITING CONDITION FOR OPERATION The calculated value of P, shall be limited to < 1.70F

t 3.2.2.1 APPLICABILITY

MODE 1*.

ACTION: With P > 1.70, within 6 hours either: y a. Withdraw and maintain the full length CEAs at or beyond the Long Term Steady State Insertion Limits of Specification 3.1.3.6 and reduce THERMAL POWER as follows: i i 1. Reduce THERKAL POWER to bring the combination of THERMAL ) POWER and FI, within the limits of Figure 3.2.2-1, or 2. Reduce THERMAL POWER to less than or equal to the limit established by the Better Axial Shape Selection System (BASSS) as a function of P; or y b. Be in at least HOT STANDBY. SURVEILLANCE REQUIREMENTS 4.2.2.1.1 The provisions of Specification 4.0.4 are not applicable. P shall be calculated as FI, =ined. using a full core power F 4.2.2.1.2 y P shall be daterm to be within its limit at the h distribution system. y following intervals: i 7 l a. Prior to operation above 70 percent of RATED THERMAL POWER after I each fuel loading, Rt b. At least once per 31 days of accumulated operation in MODE 1, and c. Within four hours if the AZIMUTHAL POWER TILT (T,) is > 0.030. n CInsed C' Y W [.2~n5 ed 3] n n ,v v See Special Test Exception 3.10.2. CALVERT ' CLIFFS - UNIT 1 3/4 2-6 Amendment No.-LIO-

3/4.? POWER DISTRIBUTION LIMITS ( 3/4.2.3 TOTAL INTEGRATED RADIAL PEAKING FACTOR - F! 3 LIMITING CONDITION FOR OPERATION j 3.2.3 The calculated value of F, shall be limited to 51.70. 4 APPLICABILITY: H0DE 1*. ACTION: With F, > 1.70, within 6 hours either: 4 a. Be in at least HOT STANDBY, or b. Withdraw and maintain the full length CEAs at or beyonf. the Long ) Term Steady State Insertion Limits of Specification 3.1.3.6 and i reduce THERMAL POWER as follows: 1. Reduce THERMAL POWER to bring the combination of THERMAL POWER and F, within the limits of Figure 3.2.3-1, or 2. Reduce THERMAL POWER to less than or equal to the limi i established by the Better Axial Shape Selection System (BASSS) as a function cf F,. When the THERMAL POWER is detennined from Figure 3.2.3-1, it g shall be used to establish a revised upper THERMAL POWER LEVEL i limit on Figure 3.2.3-2 (i.e., Figure 3.2.3-2 shall be truncated at the allowable fraction of RATED THERMAL POWER determined by i Figure 3.2.3-1). Subsequent operation shall be maintained within i the reduced acceptable operation region of Figure 3.2.3-2. SURVEILLANCE REQUIREMENTS 4.2.3.1 The provisions of Specification 4.0.4 are not applicable. 4.2.3.2 F, shall be calculated as Fr,. = F, using a full core power ~ distribution mapping system. E. shall be determined to be within its limit at the following intervals: a. Prior to operation above 70 percent of RATED THERMAL POWER after each fuel loading, Av b. At least once per 31 days of accumulated operation in MODE 1, and Within four hours if the AZIMUTHAL POWER TILT (T,) is > 0.030. c. )' Y - C J < u e < t D ] )(yy CLJed M See Special Test Exceptio J.'0.2. 4 CALVERT CLIFFS - UNIT 1 a4 2-11 Amendment No.- E & u

3/4.3 INSTRUNENTATION

)

[ 3/4.3.3 MONITORING INSTRUMENTATION. Incore Detectors LIMITING CONDITION FOR OPERATION 3.3.3.2 The Incore Detection System shall be OPERABLE with at least one OPERABLE dei c' segment in each core quadrant on each of the four axial elevations curu.ining incore detectors and as further specified below:- a. For monitoring the AZIMUTHAL POWER TILT-l At least two quadrant symetric incore detector segment groups at 1 each of the~ four axial elevations containing incore detectors in j the outer 184 fuel assemblies with sufficient OPERABLE detector 1 segments in these detector groups to compute at least two AZIMUTHAL' POWER TILT values at each of the four axial elevations t containing incore detectors. A b. For recalibration of the Excore Neutron Flux Detector System: i 1. At least 75% of all incore detector segments,

2. ' A minimum of 9 OPERABLE incore detector segments at each i

g detector segment level, and 9 3. A minimum of 2 OPERABLE detector segments in the inner 109 fuel assemblies and 2 OPERABLE segments in the outer 108 f fuel assemblies at each segment' level.- I c. For monitoring the UNRODDED PLANAR RADIAL PEAKING FACTOR, the { UNRODDED INTEGRATED RADIAL PEAKING FACTOR, or the linear heat rate: VV4 1. At least 75% of all incore detector locations,- j 2. A minimum of 9 OPERABLE incore detector segments at each detector segment level, and -i 3. A minimum of 2 JPERABLE detector segments in the' inner 109 i fuel assemblies and 2 OPERABLE segments in the outer 108 fuel assemblies at each segment level. 'l

(

An OPERABLE incore detector segment shall consist of 'tn OPERABLE rhodium j detector constituting one of the segments in a fixed detector string. An OPERABLE incore detector location shall consist of a string in which at ( least three of the four incore detector segments are OPERABLE. j V [Znsert E'3 ) Q [f nJC y K-p [ L.5e d .f CALVERT CLIFFS - UNIT 1 3/4 3-31~ Amendment No. 469-l -.

ATTACHMENT /3) DESCRIPTION OF PREVIOUS ANALYSES About a third of the way through Cycle 6 of Fort Calhoun Unit 1,18% of the detector strings ' 'd failed. Most of the failures were in detectors that had been in the core for four or five cycles, wh the rest of the failed detectors in their second cycle (Reference d). Synthesis uncertainties were evaluated for the observed failures and for extrapolated failures which considered all the oldest detectors failed as well as those in the core for their second cycle. This represented failure of 75% of the detector strings. The synthesis uncertainties were 1-2% below those in the topical report for both the observed and extrapolated failure patterns. The maximum increase in the synthesis uncertainties for 75% failures was less than 1%. This translated into an increase of 0.4% in the overall CECOR uncertainty for the extrapolated failure pattern. i ~ c overall CECOR uncertainties were only slightly higher than the topical values, because tbr s ~rved higher than normal basic detector measurement uncertainty caused by the detectors in the core for their fourth and fifth cycles l had already been incorporated. Een so, the resulting overall uncertainties were below the interim values allowed at that time. Hwever, as a conservative measure, the CECOR uncertainties were increased by 1% over the interim values to allow contin"ed operation with up to 80% failures. Administrative changes regarding surveillance and the calculation of alarm limits were implemented. Near the end of Cycle 4 of St. Lucie Unit 1,13% of the detector strings had failed. The detectors ranged from those new in Oc cycle to those in their third cycle. Various extrapolated failure patterns within these instruments, assuming that up to 60% of the strings failed, were considered l (Reference c). It was found that the synthesis uncertainties for the observed and extrapolated failure j patterns were less than those in the topical report. Again the maximum increase in the synthesis uncertainties with increased failures was less than 1%, wh.~ ; led to an increase of less than 0.3% in the overall combined uncertainty. The overall combined uncertainties were well below the topical values (and interim values in place at that time) for both the observed and extrapolated patterns. In fact, even if the observed basic detector measurement uncertainty increased by about a percent and was higher than in the topical, the overall uncertainties would still be less than those in the topical report. Based on this, continued operation without p3nalty was allowed with up to 50% failures. l Again, administrative changes regarding surveillance ad the calculation of alarm limits were l implemented. At the startup of Cycle 8 of Calvert Cliffs Unit 1,20% of the strings were failed (ku ;nce f). Most of the failures were either new detectors or the oldest, which were in their third c;cle. Synthesic uncertainties were evaluated for the known and extrapolated failure patterns assuming that up to 75% of the strings failed. "le synthesis uncertainties for both the known and extrapolated failure patterns were below those in the topical, with a maximum increase of about 0.5% for the case of extreme failures. The overall combined uncertainties increased by 0.2% even for the extreme failure assumptions. The combined overall uncertainties were less than those in the topical report even with 75% failures. In fact, the CECOR topical values would not be exceeded even if the observed basic detector measurement uncertainties were higher than those in the topical by 0.2 to 0.5E Based on l this, continued operation without penalty was allowed with up to 50% failures. An additional i commitment regarding the required surveillance interval was implemented. In summary, the increase in the CECOR uncertainties even for extreme instrument failure rates of 60-75% was in the range of 0.5 to 1%, and never exceeded 1E The CECOR synthesis uncertainty values even for the extreme failures were below those in the CECOR topical, Reference (c). The effect of the increased synthesis uncertainty on the total CECOR uncertainty never exceeded 0.4% The resulting total CECOR uncertainty even with the increased synthesis uncertainties was always below the approved topical report or interim uncertainties in place at the time. 3 I

t INSERTA: j For Unit 1 Cycle 11 only, when the percentage of OPERABLE incore detector locations (e.g., strings) falls below 75%, the measurement-calculational uncertainty factor on linear heat rate shall be increased by 1% (from 1.062 to 1.072). INSERTII: For Unit 1 Cycle 11 only, when the percentage of OPERAllLE incore detector locations i (e.g., strings) falls below 75%, this surveillance shall be performed at least once per 15 days of accumulated operation in MODE 1. INSERT C: For Unit 1 Cycle 11 only, when the percentage of OPqllAllLE incere detector locations [ (e.g., strings) falls below 75%, the calculated value of F shall be increased by 1% prior to xy comparison with the limit. INSERT D: Fcr Unit 1 Cycle 11 only, when the percentage of OPERAllLE incore detector locations (e.g., strings) falls below 75%, the calculated value of F T shall be increased by 1% prior to j r comparison with the limit. i INSERT E: l. For Unit 1 Cycle 11 only, the following requirements shall be substituted for Limiting Condition for Operation 3.3.3.2.a: At least eight quadrant symmetric incore detector segment groups containing incore detectors in the outer 184 fuel assemblies with sufficient OPERAllLE detector segments in these detector groups to compute at least one AZIMUTilAL POWER TILT value at each of the four axial elevations containing incore detectors and at least two AZIMUTilAL POWER TILT values at three axial elevations containing i incore detectors. INSERT F: For Unit 1 Cycle 11 only, the following requirement shall be substituted for Limiting Condition for Operation 3.3.3.2.b.1: At least 60% of allincore detector segments, INSERT G: For Unit 1 Cycie 11 only, the following requirement shall be substituted for Limiting Condition for Operation 3.3.3.2.c.1: At least 60% of allincore detector locations, { t}}