ML20210A504
| ML20210A504 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 01/29/1987 |
| From: | YANKEE ATOMIC ELECTRIC CO. |
| To: | |
| Shared Package | |
| ML20210A431 | List: |
| References | |
| NUDOCS 8702060485 | |
| Download: ML20210A504 (14) | |
Text
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POWER DISTRIBUTION LIMITS SURVEILLANCE REQUIREMENTS (Continued) 4.2.1.2 The below factors shall be included in the calculation of peak full power LHGR:
Heat flux power peaking f actor, F, measured using incore instrumentation 4.
at a power 110%.
b.
The multiplier for xenon redistribution is a function of core lifetime as given in Figure 3.2-3.
In addition, if Control Rod Group C is inserted below 80 inches, allowable power may not be regained until power has been at a reduced level defined below for at least twenty-four hours with y
Control Rod Group C between 80 and 90 inches.
J Reduced Power = Allowable fraction of full power times multiplier given in Figure 3.2-4.
Exceptionc:
1.
If the rods are inserted below 80 inches and power does not go below the reduced power calculated above, hold at the lowest attained power level for at least twenty-four hours with Control Rod Group C between 80 and 90 inches before returning to allowable power.
2.
If the rods are inserted below 80 inches and zero power is held for more than forty-eight hours, no reduced power level need be held on the way to the allowable fraction of full power.
c.
Shortened stack height factor, 1.009.
d.
Heasurement uncertainty:*
1.
1.05, when at least 17 incore detection system neutron detector thimbles are OPERABLE, or 2.
1.068, when less than 17, and greater than or equal to 12, incore l
detection system neutron detector thimbles are OPERABLE, or 3.
1.000, when less than 12, and greater than or equal to 9, incore detection system neutron detector thimbles are OPERABLE.
Amendment No. pi, J, JO, J7', ps, J0(
I YANKEE.ROWE 3/4 2-2 8702060485 870129 PDR ADOCK 05000029 PDR p
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POWER DISTRIBUTION LIMITS SURVEILLANCE REOUIREMENTS 4.2.2.1 F shall be determined to be within its limit by:
q a.
Using the movable incore detectors to obtain a power distribution map:
1.
Prior to initial operation above 75% of RATED THERMAL POWER after each fuel loading, and 2.
At least once per 1000 Effective Full Power Hours, b.
Increasing the measured Fq component of the power distribution map by:
1.
4% to account for engineering tolerances, 2.
5% when at least 17 incore detection system neutron detector thimbles are OPERABLE, to account for measurement uncertainty, 3,
6.8% when less than 17, and greater than or equal to 12, incore detection system neutron detector thimbles are OPERABLE, to account for measurement uncertainty, 4
8.0% when less than 12 and greater than or equal to 9, incore detection system neutron detector thimbles are OPERABLE, to account for measurement uncertainty, and I
S.
3% to account for fuel densification.
4.2.2.2 When F is measured pursuant to Specification 4.10.2.2, an overall q
measured Fq shall be obtained from a power distribution map and increased by:
1.
4% to account for engineering tolerances, 2.
5% when at least 17 incore detection system neutron detector thimbles are OPERABLE, to account for, measurement uncertainty.
3.
6.8% when less than 17, and greater than or equal to 12, incore l
detection system neutron detector thimbles are OPERABLE, to account for measurement uncertainty, 4
8.0% when less than 12, and greater than or equal to 9, incore detection system neutron detector thimbles are OPERABLE, to account for measurement uncertainty, and 5.
3% to account for fuel densification.
i 4.2.2.3 The provisions of Specification 4.0.4 are not applicable.
i AmendmentNo.p3',Jf.7(J00' YANKEE-ROWE 3/4 2-9
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POWER DISTRIBUTION LIMITS
, SURVEILLANCE REQUIREMENTS l
N 4.2.3.1 F 6H shall be determined to be within its limit by using the movable incore detectors to obtain a power distribution maps a.
Prior to operation above 75% RATED THERMAL POWER af ter each fuel loading, and b.
At least once per 1000 Effective Full Power Hours, c.
The provisions of Specification 4.0.4 are not applicable.
4.2.3.2 The measured FNAH of 4.2.3.1 above shall be increased, for measurement uncertainty, by:
a.
5%, when at least 17 incore detection system neutron detector thimbles are OPERABLE; or b.
6.8%, when less than 17, and greater than or equal to 12, incore l
detection system neutron detector thimbios are OPERABLE, or c.
B.0%, when less than 12, and greater than or equal to 9, incore detection system neutron detector thimbles are OPERABLE.
AmendmentNo.33I;FI,Jf,J7.,L&6' YANKEE.ROWE 3/4 2 11 l
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I INSTRUMENTATION INCORE DETECTION SYSTEM LIMITING CONDITIONS FOR OPERATION 3.3.3.2 The incore detection system shall be OPERABLE with:
At least twelve (12) neutron detector thimbles OPERABLE.
a.
b.
A minimum of two (2) OPERABLE neutron detector thimbles per core quadrant, and Sufficient OPERABLE movable neutron detectors, drive and readout c.
equipment to map these thimbles.
Exception:
For Cycle 19, Items a and b above are not required if there are at least nine (9) detector thimbles OPERABLE and a minimum of one (1) OPERABLE neutron detector thimble per quadrant.
APPLICABILITY: When the incore detection system is used for core power distribution measurements.
ACTION With the incore detection system inoperable, do not use the system for the above applicable monitoring or calibration functions. The provisions of Specifications 3.0.3 and 3.0.4 are not applicable.
SURVEILLANCE REQUIREMENTS 4.3.3.2 The incore neutron detectors shall be demonstrated OPERABLE by normalizing each detector output to be used within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> prior to its use for core power distribution measurements.
YANKEE-ROWE 3/4 3-23 AmendmentNo.$$,p[,,7I,77ef9b.)3hI' I
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3/4.2 POWER DISTRIBUTION LIMITS BASES (Continued)
The limits on power level and control rod position following control rod insertion were selected to prevent exceeding the maximum allowable linear heat generation rate limits in Figure 3.2-1 within the.first few hours following return to power after the insertion. With Yankee's highly darped core, the 24 j
hour hold allows sufficient time for the initial xenon maldistribution to accommodate itself to the new power distribution. The restriction on control rod location during these 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> assures that the return to allowable fraction of full power will not cause additional redistribution due to rod motion.
After 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> at zero power, the average xenon concentration has decayed to about 20% of the full power concentration.
Since the xenon concentrations are so low, an increase in power directly to maximum allowable power creates transient peaking well below the value imposed by the xenon redistribution multiplier. Thus, any increase in power peaking.due to this operation is below the value accounted for in the calculation of the LHGR.
These conclusions are based on plant tests and on calculations performed with the SIMULATE three dimensional nodal code used in the analysis of Core XI (reference cycle) described in proposed Change No. 115, dated March 29, 1974 The Factors d, e, and f in Specification 4.2.1.2 will be combinedThis statistically as the " root-sum-square" of the individual parameters.
method for combining parameter uncertainties is valid due to the independence l
of the parameters involved. Factor d accounts for uncertainty in~the power j
i distribution measurement with the movable incore instrumentation system.
I Factor e accounts for uncertainty in the calorimetric measurement for determining core power level. Factor f accounts for uncertainty in engineering and fabrication tolerances of the fuel. Together thes'e factors, when combined statistically, yield an uncertainty of 9.4% for less than 12 operating thimbles, 8.5% for less than 17, and greater than or equal to 12 operating incore thimbles and 7.1% f or greater than 17 opera'.ing thimbles.
This factor and Factors a, b, c, and g will be combined multiplicative1y to obtain peak LHSR values.
3/4.2.2 and 3/4.2.3 HEAT FLUX HOT CHANNEL FACTOR AND NUCLEAR ENTHALPY RISE HOT CHANNEL FACTOR Thb limits on heat flux and enthalpy hot channel factors ensure that
- 1) the design limits on peak local power density and minimum DNBR are not exceeded, and 2) in the event of a LOCA the peak fuel clad temperature will not exceed the 2200 F ECCS acceptance criteria limit.
0 Each of these hot channel factors are measurable but will normally only be determined periodically as specified in Specification 4.2.2.1 and 4.2.3.1.
This periodic surveillance is suf ficient to insure that the hot channel f actor limits are maintained provided:
B3/4 2-2 Amendment No. h5, JB', JIKI f
I YANKEE-ROWE
b ATTACHMENT A The Yankee loading patterns and power distributions have been very similar for several cycles. As an indication of this, Figures A-1 and A-2 show the measured values of F and F for Cycles 16 - 18.
As can be seen, there q
AH are minor differences between cycles. Cycle 19 values are also expected to be-within the same range.
The analytical modele used to predict the radial power distribution have been consistent over the past several cycles. As an illustration of the accuracy of the models, Figures A-3 through A-5 show a comparison of the measured and predicted reaction rates for Cycles 16 - 18.
These comparisons are early in cycle life where the percent difference is usually greatest. As can be seen, the predictions are quite accurate.
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- t YANKEE CORES 16-18 F0 VS. EXPOSURE 3.0 7
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EXPOSURE fGND/NTU) l
YANKEE CORES 16-10 l
P-DELTR-H VS. EXPOSURE 2.0 o - LIMIT l.8 o'- CYCLE 16 i
a - CYCLE 17 j
+ - CYCLE 18 1.84 :
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10 12 14 18 EXPOSURE (GWD/MTU)
FIGURE A-3 COMPARISON OF MEASURED AND PREDICTED SIGNALS INCORE RUN YR--16-013 599.9 MWT. GROUP C AT 85.0 INCHES 1T72. MWD /MTU 0.605 0.614
-1.455 1.004 1.079
-1.450 1.016 1.034 1.029 1.051 i
- 1.2 41
-1.663 1.031 1.10 0 1.051 1.085
-1.901 1.385 1.084 1.019 1.063 1.024 1.987
-0.492 1.074 1.063 1.0 41 1.11 0 1.045 1.0B5 1.051 2.3 11
-0.573 1.045 1.028 1.051 1.029
-0.569
-0.058 0.662 1.084 MEASURED SIGNAL 0.646 1.079 PREDICTED SIGNAL 2.446 0.404 PERCENT DIFFERENCE AVERAGE ABSOLUTE DIFFERENCE BETWEEN MEASURED AND PREDICTED 1265 PERCENT RMS ERROR 1.449
FIGURE A-4 J
COMPARISON OF MEASURED AND PREDICTED SIGNALS INCORE RUN YR-17-013 1656. MWD /MTU 599.3 MWT. GROUP C AT 84.9 INCHES 0.686 0.687 0.0 O.981 0.987 1
-0.6 1.013 1.007 1.012 0.993
' O.2 1.4 1.012 1.11 0 1.000 1.097 0.3 1.2 1.139 1.093 1.14 4 1.092
-0.4 0.0 f
1.136 1.136 0.0 1.12 0 1.0 17 1.115 1.004 0.5 1.3 1.023 1.023 0.0 0.667 0.996 WEASURED SIGNAL l
0.690 1.012 PREDICTED SIGNAL
-3.4
-1.6 PERCENT DIFFERENCE l
AVERAGE ABSOLUTE DIFEERENCE BETWEEN MEASURED AND PREDICTED 0.788 PERCENT RMS ERROR 1.195 4
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FIGURE A-5 COMPARISON OF MEASURED AND PREDICTED SIGNALS INCORE RUN YR-18-010 600.0 MWT. GROUP C AT 83.625 INCHES 1738. MWD /MTU 0.670 0.690
-2.9 1.099 1.142
-3.7 1.051 0.983 1.050 0.979 0.1 0.3 0.989 1.104 0.981 1.078 0.8 2.4 1.070 1.069 1.038 1.054 3.0 1.5 1.057 1.032 2.4 1.10 6 0.989 1.081 0.987 2.3 0.2 1.054 1.060
-0.5 0.651 1.11 0 MEASURED SIGNAL l
0.672 1.157 PREDICTED SIGNAL
-0.1
-4.0 PERCENT DIFFERENCE AVERAGE ABSOLUTE DIFFERENCE BETWEEN l
l MEASURED AND PREDICTED 1.945 PERCENT b
RMS ERROR 2.352
ATTACHMENT B Description of Fixed Incore Detector System for Yankee Rowe FIXED INCORE DETECTOR SYSTEM The Fixed Incore Detector System (FIDS) will consist of Incore Detector Assemblies (ICDS) and a Computer-Based Data Acquisition System (CBDAS).
The detectors will be inserted into existing failed neutron flux thimbles and will produce an electrical current signal proportional to neutron flux.
The CBDAS will be used to acquire, store, and retrieve the' data representative of neutron flux.
It will consist of: a Data Acquisition System (DAS) to measure and condition the Self-Powered Neutron Detectors' (SPNDs') signals, a FIDS computer (Computer) to receive the signals and store / retrieve data, and the software to control the flow of data.
INCORE DETECTOR ASSEMBLIES Each of the ICDS will contain five SPNDs and five background detectors.
All j
five of the background signals from each ICD will be used to provide gamma (i.e., background) compensation in the DAS front-end hardware.
The design of the ICDc was based on the following:
Prior to the 1985 refueling outage, the applicable incore assembly drawings were reviewed; and it was determined that installation of fixed detectors was feasible.
During the 1985 refueling outage, on-site measurements were made to record the length of each detector thimble tube. The thimble tubes were also gauged by passing a 0.184-inch diameter wire through the thimble. Based on the measurement and gauging, the length of the detectors was established; and the detector diameter was established as 0.162 inches.
In order to obtain reasonable assurance that the detectors could be inserted into the incore package, a mock-up of a typical thimble tube was assembled. A test detector was inserted into the thimble tube mock-up several times, and the insertion forces were measured and recorded. The maximum insertion force required was 23 pounds.
COMPUTER-BASED DATA ACOUISITION SYSTEM The CBDAS will be used to collect, process, store, and retrieve data associated with the FIDS.
The CBDAS will be fully tested prior to installation. The following hardware and software comprise the CBDAS:
1.
The DAS (front-end hardware) will be installed inside the Vapor Container (VC).
It will consist of an electronic instrument channel for each of the SPNDs. The instrument channels will receive, condition, and digitalize the signals as appropriate for proper interface with the Computer.
,1
4 ATTACHMENT B Description of Fixed Incore Detector System for Yankee Rowe (Continued) 2.
The computer will consist of the hardware required to communicate with the DAS, to record the value of each combined SPND and background signal together with time tracking for each signal, to keep track of tha expended charges associated with each SPND, to provide data outputs on demand, and to use a start-up routino to update the expended charges following a period of Computer or DAS downtime.
3.
The software necessary to interface the Computer with the DAS and with the operator of.the system. This software is as follows:
The software necessary to control the operation of the DAS including the exchange of information between the DAS and the Computer.
The software necessary to calculate the expended charge for each SPND.
The software necessary to recover and update the expended charge following a loss of electrical power to the CBDAS during periods of reactor operation.
The software necessary to provide for the storage and retrievel of data.
INSTALLATION As identified above, measurements and tests have been conducted to provide assurance that the design and fabrication of the ICDS will allow installation of the ICDS in the existing thimble tubes. Problems with installation are not expected.
Also, as identified above, the CBDAS will be furnished as a complete system, factory tested and ready to run af ter installation. The system uses off-the-shelf hardware; and problems with delivery, installation, and operation are not expected.
Installation of FIDS is expected to be completed during, or shortly after, the 1987 refueling outage. The location of the fixed detectors is provided in Figure B.1.
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Control Follower Type A Type B Instrumentation Location Location Assembly Assembly Tube PROPOSED INSTRUMENTATION LOCATIONS AFTER 1987 REFUELING I
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