ML20148N383
| ML20148N383 | |
| Person / Time | |
|---|---|
| Site: | Maine Yankee |
| Issue date: | 11/15/1978 |
| From: | Groce R Maine Yankee |
| To: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| WMY-78-102, NUDOCS 7811270086 | |
| Download: ML20148N383 (26) | |
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%m g u Ll b b TURNPlKE ROAD (RT. 9) g CZj ENGINEERING OFFICE WESTBORO, MASSACHUS ETTS 01581 617-366-9011 har:cO B.3.2.1 WMY 78-102 November 15, 1978 United States Nuclear Regulatory Commission Office of Inspection and Enforcement Region I 631 Park Avenue King of Prussia, Pennsylvania 19406 Attention: Boyce H. Grier, Director
Reference:
(1) License No. DPR-36 (Docket No. 50-309) (2) MYAPC Letter to USNRC, PC-64-1, (m Y 78-62) dated June 26, 1978 (3) MYAPC Letter to USNRC, (WY 78-82) dated August 15, 1978
Dear Sir:
Subject:
Maine Yankee Startup Test Report Pursuant to the MYAPC Technical Specifications, item (2) of Section 5.9.1.1 and within the ninety days following resumption of commercial powar operation delineated in item (2) of Section 5.9.1.2, we are submitting to you in Attachment A a description of the Startup Tests conducted at Maine Yankee prior to Operation of Cycle 4. Attach-ment B provides an explanation of the Cycle 4 calculational model changes. In addition, the results and analysis of a special CEA drop test at power are included in Attachment C. We trust that this inforcation is satisfactory and sufficient. However, should you desire any additional information, please feel free to contact us. l Very truly yours, MAINE YANKEE ATOMIC POWER COMPANY Robert H. Groce Licensing Engineer CMS /em Enclosures - cc: United States Nuclear Regulatory Commission (36 copies) i Director, Office of Inspection and Enforcement j l Washington, D. C. 20555 g, j
\
7811270084 u
l l Attachment A l 1 MAINE YANKEE CYCLE 4 l l L Startup Test Report i Maine Yankee initiated system heatup for Cycle 4 on August 23, 1978 after reloading the core in basic accordance with the loading pattern documented in Proposed Change No. 64 (Reference 2) and its supplements. The startup tests (acceptance criteria outlined in Reference 3) were performed from August 24 to October 30, 1978, the latter the completion date for power testing. The plant is currently restricted to approximately 97% power due to a back end loading problen with the low pressure turbine. The 97% power level testing completed the startup physics testing program for Cycle 4. The core loading represented that previously documented with the exception of the assembly in core location R7. The proposed Type E assembly for this location, with an exposure history of 20404 MWD /MT, was mishandled during l l l refueling operations. This assembly was replaced by a similar Type E assembly I with an exposure history of 20634 MWD /MT. The similarities of the assemblies 1 are such that there were no anticipated core performance differences. The startup tests performed were subject to the acceptance criteria in Reference 3, as given in Table 1. Each of the following tests is detailed below with the results compared to those predicted in Table 2. In these comparisons the nominal measured value is compared to the nominal calculated
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. .. . _ . . - _ _ . _ . . _ _ . _ _ . ~ . .
1
-. i <
, value, the latter corrected for any difference between the measurement and calculational conditions.
- 1. Critical Boron Concentrations The approach to criticality was begua on August 24', 1978 by withdrawal of-
~
all CEA's'except Bank 5. A di1ution was initiated with Bank 5 partially inserted until the reactor was critical. A final ARO critical boron - concentration of 1039 ppm was established, compared to the predicted value'of 1097 ppm. The deviation of 58 ppm was within the acceptance criteria of +1%6p (approximately +87 ppm). A rodded critical conditon was established with Banks 5 through 1 (the regulating banks) inserted. A final critical boron concentration of 828 ppm was achieved, compared to _a predicted value of 861 ppm. The deviation for the rodded case between measurement and prediction was thus 33 ppm.
- 2. CEA Bank Worths The CEA worth of all regulating Banks 5 through 1 in the non-overlap.
condition were measured via a reactivity computer. The individual bank worths are given in Table 2. The total worth of Banks 5-1 was measured as 2.649% 6p compared to'a predicted worth of 2.675%Ap. The difference from the_ predicted, 1 " which is +1.0% of the total measured worth, is within the acceptance criteria of +10.0% in total worth. 4 e I
- 3. Eiected CEA Uorth The worth of the most limiting near full power ejected CEA was measured at the zero power condition. The ejected CEA is a Bank 5 (2 full strength finger) CEA from the Banks 5 + 4 in configuration. The single CEA had a neasured worth of 0.0477Ap compared to a predicted worth of 0.111%Ap , which is well below the acceptance criteria of measured worth no more than 15%
o,reater than the predicted worth.
- 4. Isothermal Temperature Coefficient at il7.P The ITC was measured at the ARO and Banks 5-1 inserted conditions at zero nouer. As given in Table 2, a measured ARO ITC of +0.38(10~ Ap/ F) was
~
obtained, compared to a predicted value of +0.15(10 ^Ap/ F). The dif ference of 0.23(10~ Ap/ F) was within the acceptance criteria of
~ +0.50(10 'Ap/ F) for the ARO condition.
- 5. CEA Drop Times The measured drop time for 90% insertion for each individual CEA was perfonned f rom the hot zero power condition. The values were compared to the Technical Specification limit of 2.70 seconds. All CEA's achieved 90%
insertion within 7.37 seconds, the slowest CEA one of those in the unsleeved demonstration fuel assembly locations. The average time of insertion was 2.18 seconds with a standard deviation of 0.10 seconds.
- 6. CEA Svmmetrv Checks
.. _ , _. ._ _ __ _. . _ _ _ _ _ _ _ _ . - - . . . .. _ _ _ _ . . _ . . ~
The individual CEA's in Banks 4 and C were measured in the zero power condition in order to identify any significant core tilt before power escalation. An acceptance criteria of +10% is placed on the individual CEA worths compared to the average worth. The measurements detailed in Table 2 4 yielded maximum dif ferences of 12.2% for Bank 4 and 15.5% for Bank C. The locational dependencelaf the worth measurements indicated that there existed a core tilt at zero power. A similar condition existed for the Cycle 3 startup, the core tilt declining with~ increasing power level. Cycle 3 operated with an average measured tilt of 1.3-1.4% during the cycle at full power. Both the Cycle 3 and Cycle 4 zero power tilt measurements thus indicated that this measurement is not representative of a significant core tilt.at higher reactor power levels. In conclusion, it is felt that power levels significantly higher than those employed in low power physics testing must be attained in order to measure a tilt value representative of power operation.
- 7. INCA Tilt Monitoring Due to the detectable core tilt condition identified at zero power, INCA
- incore ( as well as excore) tilt was monitored at least each 5% in core power 1
l during power escalation. The values in Table 2 indicate that the core tilt of t i e - . . .-...-..,--.v,-- . , . . . ~ , , - , . , - - - , , - - - . . ~ ~ , ~ , - ~ - . , , . . , - - . a. nn-,,--.- --m-.-~w,--,,-~,~rr-vw ~---,v~, - ->
4.9% at 1% power decreased steadily with increasing power. The final core tilt of 2.4% at 48.2% power was within the Technical Specification limit of 3.0% near 50% power. The incore and excore indications of the core tilt were consistent in terms of both the magnitude and decline of the tilt . .
- 8. Isothermal Temocrature Coef ficient at 50% Power i
The ITC was measured at the near 50% power condition. A measured -
! value of -0.09(10" op / F) was obtained. The predicted value of l
~
-0.24(10 Ap / F) was in deviation from the measured value by
-0.15(10" Ap / F) . The measured and calculated ITC values reficct an ARO equilibrium boron concentration of 814 ppm.
- 9. Power coefficient at 50% Power The doppler only power coefficient near 50% power was measured as
-0.0095%AP/% power. The predicted value of -0.0093%Ap/% power was well within the acceptance criteria of 125%.
- 10. Power Distribution Measurements Power distribution measurements via INCA were performed during power i escalation. The equilibrium power' distribution measured near 50% power is I
compared to the predicted power distribution in Figure 1. The comparison shows exec 11ent agreement, well within the acceptance criteria of 110% for each individual assembly. A maximum deviation of 4.4% is seen, with a deviation of 2.1% in the limiting assembly. F v,.e,,._,.. ,._%. , - -_.,m... ,,,_.%wmq _n,..,.w,,,m,... rm,..r._.g. . ~p. ,,.,,m, .,_,wp,.,,y.._%,,, ,,,,..,.y,....,, , , , , -,,,,,,,,,%,,,, ,,,,,,_yyp., - - , - ,9-a
I l l l l I Plant prchlec..e resulted in extended BOC operation at less than full power. A near full power comparison of power distributions at approximately 1200 ffWD/MT is presented in Figure 2. Excellent agreement is witnessed again, with a deviation of 0.1% in the limiting assembly.
- 11. Control Rod Drop at Power (See Attachment C) i e
P l 4
, - , .-- . . . , . w
Tabic 1 i Maine Yankce Cycle 4 - Startup Test Acceptance Criteria Measurement Conditions Criteria
- 1. Critical baron Hot zero power, near Measurement within t concentration all rods out il%ap of predicted value
- 2. CEA bank t7rths Hot zero power, Total worth within CEA Banks 1+2 110% of the predicted
+3+4+5 in the non- value overlap condition 6
3.} CEA bank worths Hot zero power, If the criteria in CEA Banks A+B+C+ Meas ament (2) is not i 1+2+3+4+5 in the non- met, the total worth overlap condition of all CEA banks must be within 110% of the predicted value
- 4. Ejected CEA Worth Hot zero power, pre- Ejected CEA worth ejection CCA Banks no more than 15%
inserted for measure- greater than the ment of the most predicted valta limiting near full power ejected CEA
- 5. Isothereal temperature Hot zero power, nea r Measuremen coefficient all rods o.;e +p.5 x 10 gap/oF within of predicted value L
'rol rod drop times Oparating temperature, Drop times no greater ) insertion to 90% than 2.70 seconds checks Hot nero power, the Measurement of each individual CEA worths individual CEA within in CEA Bank 4 and CEA ,10% of the CEA bank Bank A or C average t naaltoring 5-48% of rated power, If the criteria in
) near all rods out Measurement (7) is not met, tilt is monitored at 5% powur intervals
- 9. Radial power distri- At or slightly below Each assembly average butions 50% power, near all power within 110% of rods out predicted value
- 10. Power coefficients At or slightly below Measurement within 50% power, CEA Bank 5 25% of predicted value partially inserted
' ' " - A---_____ _ _ _ _ _ _ _ _ _ _ _ . _ _ _ _ _ _ _ _ _ _ _ _ _ _ , _ _ _ _ _ , _ _ , _ , . _ _ _ _ _ _
Table 2
.M1 e Yankee Cycle 4 Ster:up Test .feasurements and Predictions Item Units Fieasurement Prediction Deviation Criteria
- 1. Critical boron concentration ppm ARO
~
1039 1097 58 11%Ap (87 ppm) Banks 5--1 828 , 861 33 -
- 2. CEA Bank Worths %Ao 5 0.492 0.496 +0.8%
4 0.341 0.335 -1.8% 3 0.605 0.587 -3.0% 2 0.547 0.537 -1.8% = 1 0.664 0.720 +8.4% Total 5-1 2.649 2.675 +1.0% +10%
- 3. Ejected CEA Worth 5+4+ Ejected 5 %AP 0.097 0.111 -14.4% <+15%
(2 finger)
- 4. Isothermal Temp-erature Coeff-ient at ilZP 10-4Apjop ARO +0.38 +0.15 -0.23 +0.50 Panks 5-1 -0.41 -0.90 -0.49 -
- 5. CEA Drop Times seconds 2.18 avg. - - less than 2.70 seconds .
2.37 worst - -
Table 2 (continued) Maine Yankee Cycle 4 Startup Test Measurements and Predictions Item Units Measurement Prediction Deviation Criteria
- 6. CEA s.nnmetry %Ao checks Bank 4 Rod 2 0.0645 -
-5.0% 110%
Rod 3 0.0762 -
+12.2% 110%
Rod 4 0.0688 -
+1.3% +10%
Rod 5 0.0620 -
-8.7% ~+10%
Bank 4 Average 0.0679 Bank C Rod 46 0.0442 -
-13.1% +10%
Rod 47 0.0475 -
-6.7% T10%
Rod 48 0.0514 --
+1.0% T10%
Rod 49 0.0588 -
+15.5% T
_10% Rod 50 0.0575 -
+13.0% +10%
Pod 51 - 0.0541 -
+6.3% T10%
Rod 52 0.0496 -
-2.5% T10%
Rod 53 0.0440 -
-13.5% +10%
Bank C Average 0.0509
- 7. INCA Tilt Monitoring Percent rated % Incore power Tilt 1.0 4.9 - - _
4.8 3.8 - - 8.1 3.6 - - - 11.2 3.4 - - - 15.8 3.0 - - - 17.9 2.8 - - - 21.8 2.6 - - - 25.7 2.5 - - - 29.3 2.5 - - - 32.1 2.5 - - - 36.8 2.4 - - - 41.1 2.4 -- - - 44.4 2.4 - - - 48.2 2.4 - - <3.0
^
Table 2 ~ (continued) l Maine Yankee Cycle 4 Startup Test Measurements and Predictions Item Units Measurement Prediction . Deviation Criteria
- 8. Isothermal Ter:p-erature Coefficient near 50% Power 10 Ap/ 0 F j l
ARO -0.09 -0.24 -0.15 --
- 9. Power Coefficient %Ap per -0.0095 -0.0093 -2.1% +25 .0%
At 50% Power % Power _ ~ . V u____ _ - _ _ _ _ _ _ ___ _ _ _ _ _ _ _ _ __.___. _..-m _ _ . _ _. _ _
l Figure 1 Maine Yankee Cycle 4 Assembly Relative Power Densities l INCA versus Predicted ' BOC, ARD, Equilibriur Conditions 1 near 50% Power Assembly Type and INCA Location . . . . . . . . . . . . . I-0 8 I-0 21 INCA at 48% Power ............. 0.659 0.871 Predicted at 50% Power ............. 0.647 0.884 Percent Difference ............. -1.8 +1.5, I-0 15 I-0 31 1-0 11 E-16 25 1-4 4 0.709 0.895 1.009 0.885 1.197 0.678 0.890 1.034 0.885 1.221
-4.4 -0.6 +2 5. +0 0
. +2.0 1-0 16 1-4 33 E-16 13 E-16 28 I-4 7 E-16 20 0.829 1.135* 0.891- 0.891 1.172 0.939 0.824 1.135 0.910 0.874 1.195 0.946
- -0.6 +0.0 +2.1 -1.9 +2.0 +0.8 i
i I-4' 34 F-0 14 H-0 30 G-42' 10 E-16 24 G-0 3 1.174 0.918 1.112 0.928 0.918 1.019 1.199*' O.958 1.129 0.962 0.914 1.046
+2.7
+2.1 +4.4 +1.5 +3.7 -0.4 H-0 32 G-0 12 E-16 27 H-0 6 G-42 19 1.139 1.029 0.967 1.212 1.107 1.158 1.036 0.943 1.206 1.116
+1.7 +0.7 -2.5 -0.5 +0.8 F-0 29 H-0 9 E-16 23 H-0 2
- 0.948 1.250 1.022 1.239 0.928 1.209 0.995 1.226
-2.1 -3.3 -2.6 -1.1
~
N E-16 26 H-0 5 G-41 18
. 1.001 1.201 1.110 0.966 1.187 1.100
*Kayimum 1-Pin
-3.5 -1.2 -0.9
-16 22 G-0 1 Measured 1.367 _1.010 1.071
' Predf-ted 1.405 0.978 1.036 Differ'::e 2.8% -3.2 -3.3 E-16 12 Percent Difference: Pred-INCA x 100 0.936 INCA 0.912
-2.6 i
l
-=v -- -
g w ,. +-
Figure 2 Maine Yankee Cycle 4 Assembly Relative Power Densities l INCA versus Predicted i BOC, ARD, Equilibrium Conditfor.s near HFP ! 1 Ii Assembly T I-0 8 I-0 21 INCA at 97%ype Power,1187 and INCA MWDLocation/MT . . . . . . . . . . . . .
............... 0.670 0.885 f Predicted at 100% Power, 1200 MWD /MT........... 0.636 0.862 '
Percent Difference ............................ -5.1 -2.6 I-0 15 I-0 31 1-0 11 E-16 25 I-4 4 0.696 0.897 1.018 0.901 1.220* 0.648 0.862 1.017 0.892 1.219*
-6.9 -3.9 -0.1 -1.0 -0.1 .
1-0 16 1-4 33 E-16 13 E-16 28 I-4 7 I-16 20 0.803 1.121 0.897 0.905 1.204. 0.959 0.780 1.091 0.902 0.896 1.222 0.976
-2.9 -2.7 0.6 ~1.0 1.5 1.8 I-4~ 34 ' F-0 14 H-0 1K) G-42 10 E-16 24 G-0 3 1.151 0.908 1.107 0.945 0.932 1.042 1.144 , 0.934 1.128 0.990 0.947 1.076
-0.6 1 2.9 1.9 j4.8' 1.6 3.3
' H-0 32 G-0 12 E-16 27 H-0 6 G-42 19 1.121 1.023 0.966 1.201 , 1.101 1.141 1.036 0.971 1.219 1.134 1.8 1.3 0.5 1.5 3.0 F-0 29 H-0 9 E-16 23 h4-0 2 0.946 1.242 1.014 1.216 0.941 1.218 1.018 1.231
- Maximum 1-pin - -0.5 -1.9 0.4 1.2 E-16 26 H-0 5 G-41 18 Measared 1.396 0.996 1.186 1.100 Predicted 1.395 -
0.991 1.197 1.114 ! Difference -0.1% -0.5 0.9 1.3 Pred - INCA x 100 Percent Difference : E-16 22 G-0 1 INCA , 1.004 1.070 1.007 1.061 0.3 -0.8 E-10 li
. 0.938 0.951 1.4 6
,, ,, ,,,.---r , + -, , , - . - , - , - - - -,,.-c . - - , , , . , - , . _ , , v- ,.-v .m. . - - , .
i i 5 Attachment B ! MAINE YANKEE CYCLE 4 s Changes in Analytical Methods The physics analysis methods utilized in Cycle 4, as described in Section 4.8 of Proposed Change No. 64 (Reference 2) are the same as those used in Cycle 3 with the exception of the following: (1) Extension of fine mesh diffusion theory and nodal physis.s methods to the calculttion of reactivity parameters and a change in the nodal neutronics cocpling model. (2) Introduction of local pointwise doppler feedback effects in the two i dimensional pinwise PDQ calculations for large power gradient calculations (i.e., dropped CEA analysis). The change described above in item (2) is addressed in Reference 2 and
, augmented by the special CEA drop test performed for the Cycle 4 startup. The l i purpose of this section is a clarification of the application of methods in j item (1), specifically, the changes introduced in the Cycle 4 analysis for ' ~
reactivity parameter calculations. e A summary of the mode', banges with regard to the specific reactivity parameters is given in Table 1. The calculation tools and their application j i i s sek,
, I are presented in YAEC-lll5 (as referenced in the table), namely the FOG, PDQ and SIMULATE computer codes.
1 The aim of the implemented changes was to further develop pinwise PDQ ' models to more accurately represent the reactivity effects associated with j changes in moderator conditions. The models developed, as detailed in the table, allow for accurate representation of reactivity values at the specific moderator temperatues of 68 F, . 300 F, 525 F and 576 F. In parallel, extension of the capabilities of SIMULATE to accurately reflect the changes in all two group constants;as a function of moderator density over the range of 200 - 600 F enables calculation of any intermediate condition reactivity effects. The PDQ and SIMULATE tadels both specifically account for the effect of moderater conditions on the soluble boron, xenon, samarium, burnable poison and control rod cross sectional representations. The SIMULATE nodal formulation, as presented in YAEC 1115, still utilizes as basic input the batch average flux weighted PDQ two group constants versus exposure. The changes due to moderator, control rod and poison conditions are also explicity from the PDQ models, where possible.
-,v. ,,-- - . , , . - ,, .,, ,.---e , ,. - - - .-e-,,--,,,r , , - -.. ,.--,,-,.-.w. ...-,er--, - . , - , , , - - , , , . . ,
O As indicated in Table 1, the following_model changes were instituted for N 1
- the. Cycle 4 analysis:
Doppler Defect and Coefficient Calculations ( The. fuel temperature influence on the fast group contants'in SIMULATE was
! expanded to include. the temperature range of 200-4000 F by use of LEOPARD' generated batch' specific calculations. Thus, SIMULATE calculations fona the basis of doppler defect and coefficient calculations. The' greater radial, as well as. axial, spatial. detail was the determining factor in choosing SIMUALTE over the FOG model representation.
Moderator Temperaturn Coefficients and Defects , Uniform but consistent underprediction of moderator temperature coefficients by FOG for Maine Yankee led to development of a PDQ pinwise model t'or MTC calculations to obtain a more accurate spatial representation. Based , on startup results, an MTC underprediction, however, is still evident despite' the model change. F l l A PDQ model developed for calculation of HZP (525 F), ARO MTC values l l forms the basis of the MTC model'~ change. Calculations are. performed during l cycle life for a range of boron concentrations. The SIMULATE model is then-used for calculating MTC sensitivities due to moderator temperature, power and l . control rod variations. i The moderator temperature range covered oy the PDQ and SIMULATE models, as
~ _ . . _ . . _ , - - . - , _ , .-_._ . ~ ,. ... _ ., . - - - _,_ . - - - , . . . . . . ~ . . . _ . _ _ _ ~ . - - - . . - _ _ _ _ _ _ _ . -
.~. . = . . . - . .
described.above, also gives excellent representation for moderator defect calculations from 200 to 600 F for both rodded and unrodded conditions. Such defect calculations replace those previously generated by FOG for input to safety analysis calculations. ' In summary, the changes introduced in the calculation of doppler and moderator reactivities for Cycle 4, namely expanded application of a pinwise PDQ'representaion (with SIMULATE interpolation and sensitivity calculations) , is a more detailed and spatially accurate treatment compared to the FOG representation previously used. h i
T A_ B_ L E B-1 ' MAIr.E YANKEE CYCLES 3 AND 4 ANALYSES l REACTIVITY PARAMETER CALCULATIONS RanRe of Temperatures Parameter Moderator CEA _ Calculational Cages Applied (1, 2) Fuel Conditions 1. Cycle 3 Analysis Cycle 4 Analysi Boron Worths 68*F to HFP - ARO to ARI PDQ/ SIMULATE
- 2. Xe/Sm Worths PDQ/ SIMULATE +
HZP to HFP - ARO 3. PDQ/ SIMULATE .PDQ/ SIMULATE Kinetics Parameters HZP and HFP - ARO to Banks 5-1. PDQ/DENUF . 4. Doppler Defect - PDQ/DENUF { -and Coefficients 200 to 4000*F ARO FOG SIMULATE
- 5. Moderator Temperature HZP --
- Coefficients ARO FOG PDQ HZP to HFP -
i ARO to Banks 5-1 FOC 60 Moderator' SIMULATE Defect 300*F to HZP -- ARO and ARI l FOG i PDQ i 200 to 600*F -- ARO to ARI FOG SIMULATE 1 Code descriptions et.al., October in YAEC-ll15 (Application of Yankee's Reactor Physics Methods to Mai 1976). ne Yankee, D. J. Denver, 2 PDQ calculational models representing the following conditions are utilized in reactivit calculations: y parameter 1 (1) Isothermal models at 6S*F, 300*F and 525"F (HZP) (2) HFP model with 576*F average moderator conditions (3) MTC model with 500*F average moderator conditions and 525 F- average fuel conditions N 4 i
A tachment C MAINE YANKEE CYCLE 4 t CEA Drop Test l The effects of local doppler feedbackHin the analysis of the CEA drop transient were implemented utilizing th9 calculational model described in Section 4.8.2 of Proposed Change No. 64 (Reference 2). This methodology 3 incorporated calculational feedback between the pointwise power and the pointwise fuel temperature distribution in order _to correct the pointwise cross section representation for the doppler effect. This method is used only in the dropped CEA analysis calculations. The values of maximum 1 pin power presented in Proposed Change No. 64 (Reference 2) as calculated by such analysis are very similar to those calculated for Calvert Cliffs Unit I, Cycle 2 under similar CEA drop ! conditions and utilizing similar methodology. The static CEA drop test evaluation performed at Calvert Cliffs Unit I provided validation of this type of analytical technique. l l l ! An evaluation of this calculational method specifically to Maine Yankee was conducted as specified in Section 7.4 of Reference 3. A special CEA drop l test van performed to compare the measurad power distributions to predictions i made with the revised analysis methods. i
-g -
--p n - , ,,-m,,
-.- ~. -. . - ... .. - ._ ..
The special.CEA drop test consisted of allowing a dual CEA', control rod CEADM #7 in core locations-N13 and R15, to be dropped into the core. Th'is CEA represents the highest worth calculated in the CEA drop analysis from the ARO, HFP, condition at BOC for Cycle 4. Prior to the drop',,the core was at 48.8% ( power, equilibrium conditions with the first regulating control rod bank,' Bank 5, inserted into the core 22% of full length. The dropped CEA remained inserted for 20 minutes and was then slowly withdrawn. Detector response data was collected from the 34'available fixed detector etrings and a single movable detector throughout the period of the test. Figure C-1 shows the location of each detector and all inserted control rods. Core response to the full length CEA drop' test, based on the nominal measured plant data, is shown in Table C-1.' The large worth control rod caused a rapid decrease in nuclear core power level and a corresponding slower decrease in primary core average coolant temperature. Operator action, as. 4 required by Emergency Procedure 2-21, Control Rod Drop, quickly stabilized the reactor conditions by use of the feedwater regulating valve and/or the turbine t throttle valve. The fixed detector signals, representing 129 detectors (34 detector string locations, 4 detectors / string minus failed detectors) are combined to provide an axially averaged set of measured values. Each set of detector signals were internormalized to remove all secondary effects. Xenon effects, though small in the time scale of interest, were not included in the calculational results. Such an approach.is conservative by its yielding larger increases in
. . l
.relativa power for the' peak locations. The final corrected changs in the
. relative detector. responses thus corresponds'to the relative power change in ,
the given assembly locations. ! c l The calculated and measured relative change for each detector location after the CEA drop is shown in Table C-2. The data is also shown in the map of Figure C-2. .The excellent agreement between calculated and measured .) 1 changes demonstrates the applicability.of the calculational model. Notice l that for the. locations in the core with the maximum increases, i.e., greater than about 1.15 (representing a 157. increase in normalized relative signal post-drop versus. pre-drop), the increases in relative signal are, in general, . conservatively predicted. 'These detector locations (detector numbers 1,'3, 5, 7 and 27) are in those core areas where the maximum pin powers are located in the post drop condition for the given dropped CEA at BOC. I The magnitude of the maximum relative. increases, on the order of 1.19, is ! greater than the 1 pin power increases presented in Proposed Change No. 64 (Reference 2). This can be accounted for, in part, by consideration of the partial insertion of Bank 5 and the decrease in core power level and average coolant temperature during the test. Additionally, the internormalization of the set of detector signals yields larger relative increases than the actual 1 pin power increases. The relative increases shown in this test are thus consistent with the magnitude of the physics values used in the CEA drop safety analysis. The calculational model utilized for the generacion of CEA drop physics parameters has now heen justified through comparison to plant data. These
comparisons of measured and calculated results give confidence in the predictive capabilities of this model when applied to the CEA drop analysis for Maine Yankee. ( 9 N 1
=
(
-Table C-1 MAINE YANKEE CYCLE 4 Core Response t'o CEA Drop Test Measured Parameter Time after'CEA Drop 4
0 seconds 180 seconds Core Nuclear Power 48.8 35 (% of full power) Primary System Pressure' 2250 2218 (psia) Average Primary Coolant Temp. 554 548 (OF) Secondary System Pressure 880 862 (psia) l l l l l l U
% _h - -
mp -. . , ,,e vr-w+-- y t- ~ -p - - , 9 e-- e e--
- yr 7 - -i-iir- ---- -e
- w - -, e+ - m='
l j I Table C-2 MAINE YANKEE CYCLE 4 ( Comparison of Post CEA Drop / Pre CEA Drop Signal Ratios ) 2 Calculated vs. Measured Increased Signals Decreased Signals Detector Calculated Measured (C-M) Detector Calculated Measured (C-M) , 1 1.172 1.164 0.008 15 0.959 0.982 -0.023 3 1.187 1.178 0.009 20 1.036 0.999 0.037 4 1.133 1.121 0.012 22 0.793 0.824 -0.031 5 1.144 1.148 -0.004 23 0.655 0.726 -0.071 6 1.107 1.119 -0.012 24 0.902 0.936 -0.034 i 7 1.188 1.183 0.005 28 0.819 0.839 -0.020 8 1.104 1.090 0.014 29 0.655 0.730 -0.075 9 1.069 1.083 -0.014 30 0.959 0.982 -0.023 10 1.131 1.142 -0.011 33 0.793 -0.825 -0.032 11 1.086 1.058 0.028 35 0.839 0.842 -0.003 13 1.073 1.038 0.035 38 0.982 0.938 0.044 14 1.027 1.013 0.014 39 0.897 0.889 0.008 16 1.083 1.100 -0.017 40 0.938- 0.930 0.008 25 1.039 1.055 -0.016 41 0.963 0.930 0.033 27 1.161 1.130 0.011 42 0.976 0.949 0.027 32 1.154 1.136 0.018 34 1.079 1.071 0.008 37 1.122 1.100 0.022 45 1.064 1.027 0.037 . l l l 1
\
t-FICURE C-1 MAINE YANKEE CYCLE 4 DETECTOR AND CONTROL ROD LOCATIONS 21 20 19 18 17 16 15 13 11 9 7 6 5 h 3 2' 1 I l l l- l l l . I- t l l 1 I i l l j l ; l i l g I 1h 12i 10 8 I l ; i i l ( l I I ~~ ~~ ~~~~ ~~ ~~~ ~~^ J f l RH I 3 I l _l I l L- B l l l l RH -[- l~~l g
~ - ~ ~~
l l RH RH . l I 6 7 RH J~~~D l RH -{ l 8 9 10
; RH RH RH -!- ~ ~ E
( 11 I RH )
~ J- ~~ ~ y I
l L3 14 15 16 __0 RH RH RH RH H __J K 20 22 23 24 25- 27 __L Ril RH RH RH RH RH M 28 29 30 -- N RH RH RH P 31 32 __R M RH 33 34 g
- ~ ~ - - ~
Ril RH , 35 37 ____T RH RH 38 39 40 _,______y Ril RH RH 41 42 ________y ___________I 45 ________________y RH 1 .... Detector Number RH .... Detector Type RH- Rhodium fixed M- Movable
.... CEA Bank 5 (Partially inserted)
.... CEA Dual B (Dropped CEA) ,
1 , F'I-C U R E C-2 1 COMPARISON OF MEASURED AND . 1.164 - CALCULATED RELATIVE SIGNAL
~ MAINE YANKEE CYCLE 4 1.172 3 RATIOS - PRE DROP vs. POST DROP CEA DROP TEST
/ RESULTS 1.178
- i. 1.187 4 5
.1 1.121 1.148 - l 1.133 L.144 6 7 i 1.119 1.183 1.107 1.188 ll B 9 10 i 1.090 1.08 1.142 ] 1.104 1.069 1.131 11 1.058 1.086 13 14 15 j 16
- 1.038 1.013 .982 1.100 J -
1.073 1.027 .959 1.083 ' ? t-1 r .
; 20 22 23 24 25 27
.999 .824 .726 .936 1.055 1.150 t 1.036 .793 .655 .902 1.039 1.161
} - 28 29 30 *
- .839 .730 .982
.839 .665 .959 32 l
1.136 - 1.154 i 33 34 l i
.825 L.071
.793 L.079 1 35 37 i- .842 1.100 j __
.839 -
1.122 1
- 38 39 40
.938 .889 .93C '
i .982 .897 .93E i 41 42
* .930 .949
.963 .976 i
. I DETECTOR LOCATION DROPPED CEA 1.164 MEASURED LOCATION i ? ' CALCULATED-
- .-I 45 l
1.027 1.064 5 ! j; ,... i
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