View source for CP-200800264, Comanche Peak Steam Electric Station, Supplement to License Amendment Request (LAR) 07-003: Response to Request for Additional Information Related to License Amendment Request Associated with Methodology Used to Establish Core Operating

{{Adams
| number = ML080710563
| issue date = 03/06/2008
| title = Comanche Peak Steam Electric Station, Supplement to License Amendment Request (LAR) 07-003: Response to Request for Additional Information Related to License Amendment Request Associated with Methodology Used to Establish Core Operating Lim
| author name = Blevins M
| author affiliation = Luminant Generation Co, LLC, Luminant Power
| addressee name = 
| addressee affiliation = NRC/Document Control Desk, NRC/NRR
| docket = 05000445, 05000446
| license number = NPF-087, NPF-089
| contact person = 
| case reference number = CP-200800264, TXX-08032
| document type = Letter type:CP, License-Application for Facility Operating License (Amend/Renewal) DKT 50
| page count = 10
| project = 
| stage = Response to RAI
}}

=Text=
{{#Wiki_filter:Mike Blevins Executive Vice President& Chief Nuclear Officer Mike. Blevins@Luminant.com Luminant Power P 0 Box 1002 6322 North FM 56 Glen Rose. TX 76043 M WmLiuif&#xfd;l; T 254 897 5209 C 817 559 9085 F 254 897 6652 CP-200800264 Log # TXX-08032 Ref. # 10CFR50.90 March 6, 2008 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555 

==SUBJECT:==
COMANCHE PEAK STEAM ELECTRIC STATION DOCKET NOS. 50-445 AND 50-446 SUPPLEMENT TO LICENSE AMENDMENT REQUEST (LAR) 07-003 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION RELATED TO LICENSE AMENDMENT REQUEST ASSOCIATED WITH METHODOLOGY USED TO ESTABLISH CORE OPERATING LIMITS (TAC NOS. MD5243 AND MD5244)

==REFERENCES:==
: 1. Letter logged TXX-07063 dated April 10, 2007 submitting License Amendment Request (LAR) 07-003 revision to Technical Specification 3.1, "REACTIVITY CONTROL SYSTEMS," 3.2, "POWER DISTRIBUTION LIMITS," 3.3,"INSTRUMENTATION," and 5.6.5b, "CORE OPERATING LIMITS REPORT (COLR)," from Mike Blevins to the NRC.2. Letter logged TXX-07126 dated August 16, 2007 supplementing License Amendment Request (LAR) 07-003, from Mike Blevins to the NRC.3. Letter dated February 4, 2008, from Balwant Singal of NRR to Mr. Blevins.4. Letter logged TXX-08024 dated February 11, 2008 from Mike Blevins to the NRC submitting requested information supporting License Amendment Request (LAR)07-003.

==Dear Sir or Madam:==
Per Reference 1 as supplemented by Reference 2, Luminant Generation Company LLC (Luminant Power) submitted proposed changes to the Comanche Peak Steam Electric Station, herein referred to as Comanche Peak Nuclear Power Plant (CPNPP), Unit 1 and Unit 2 Technical Specifications to allow the use of several Nuclear Regulatory Commission (NRC) approved accident analysis methodologies to be used to establish core operating limits. In Reference 3, the NRC requested additional information pertaining to Reference 
: 1. Luminant Power initially responded to the request in Reference 4.However, Luminant Power would like to withdraw the letter logged TXX-08024, dated February 11, 2008 (Reference 
: 4) and provide the information requested in Reference 3 in the attachment to this letter.In addition, Luminant Power will provide' data regarding the completion of Technical Specification Surveillance Requirement (SR) 3.2.1.1 after the first six months of Unit 2 Cycle 11 operation.
A member of the STARS (Strategic Teaming and Resource Sharing) Alliance Callaway
* Comanche Peak -Diablo Canyon .Palo Verde
* South Texas Project
* Wolf Creek A loo(kj(2-9 U. S. Nuclear Regulatory Commission TXX-08032 Page 2 03/06/2008 In accordance with 10CFR50.91(b), Luminant Power is providing the State of Texas with a copy of this proposed amendment.
This communication contains the following new licensing basis commitment regarding Comanche Peak Unit 2.Commitment 
#3465995 Description Luminant Power will provide' data regarding the measurements and results from Technical Specification Surveillance Requirement (SR) 3.2.1.1 following six months of Unit 2 Cycle 11 operation.
Should you have any questions, please contact Mr. J. D. Seawright at (254) 897-0140.I state under penalty of perjury that the foregoing is true and correct.Executed on March 6, 2008.Sincerely, Luminant Generation Company LLC Mike Blevins By: Y 7  .h.redW. Madden Director, Oversight 
& Regulatory Affairs Attachment 
-Response to NRC Request for Additional Information on W(z)-Related Items #1 and #2 c -E. E. Collins, Region IV B. K. Singal, NRR Resident Inspectors, Comanche Peak Alice Rogers Environmental 
& Consumer Safety Section Texas Department of State Health Services 1100 West 49th Street Austin, Texas 78756-3189 Attachment to TXX-08032 Response to NRC Request for Additional Information on W(z)-Related Items #1 and #2 Attachment 1 to TXX-08032 Page 1 of 7 Response to NRC Request for Additional Information on W(z) Items #1 and #2 Question 1. Submit the Axial Offset (AO) Validity Criteria methodology and its technical basis for staff review and approval.Response: The use of the Westinghouse Axial Offset Validity Criteria Guidance was not discussed in the previous LARs and supporting RAI responses and will not be used at Comanche Peak Nuclear Power Plant (CPNPP) until the NRC questions associated with the generic guidance are resolved.The Comanche Peak Technical Specification 3.2.1 and the associated BASES describe the surveillance technique used to assure the total heat flux hot channel factor remains within the limit values. The technique and supporting analytical inputs are described in WCAP-10216-P-A-RIA, "Relaxation of Constant Axial Offset Control FQ Surveillance-Technical Specification," which is listed in Comanche Peak Technical Specification 5.6.5b, Item 2. The application at Comanche Peak is compliant with conditions and limitations identified in the NRC's Safety Evaluation of this topical report.As described in the Comanche Peak Technical Specification 3.2.1 and the associated BASES, the elevation-dependent total heat flux hot channel factor, FQ(z), as approximated by the terms FQc(z) and FaW(z), is periodically verified to be within the specified limits. The value of FQW(z) is derived by multiplying the value of FQC(z) (a steady-state value which includes uncertainties defined in the Technical Specification BASES) by a factor to account for potential increases in the measured value between surveillance intervals and by a factor, W(z), to account for potential transients.
W(z) is defined as the ratio of the maximum transient Fa-TR(z)*Power and the SS-FQ(z)*Power.
Standard Relaxed Axial Offsite Control (RAOC) analyses have demonstrated that the maximum transient FQ(z) (i.e., FQ-TR(z))
is insensitive to the steady state power shape since, as part of the standard RAOC methodology, the maximum elevation-dependent values of FQ(z) from a large number of power shapes covering the full range of allowed axial flux differences are used. Conservative W(z) curves are generated using the approved methodology described in WCAP-10216-P-A-RIA and are based on assumed full power conditions and a predicted steady-state axial power distribution.
Note that the effects of severe operating anomalies, such as Crud Induced Power Shift (CIPS), are addressed through recalculation of W(z)s using the approved methodology.
Relative to the definition of W(z), the following presentation may be beneficial in subsequent discussions.
The definition of W(Z) may be presented as: W(z) = max { FQ-TR(z)
* P} / {SS- FQ(Z)
* P}where the power component (P) will be discussed later.Because of the large number of transient power shapes considered in its development, the maximum value of FQ-TR(z) is insensitive to the assumed steady-state power distribution.
The SS- FQ(z) may be further approximated with axial and radial components (P(z) and Fxy(z)). Recognize that for a given core design, the radial component is relatively constant while the axial component is variable.
Attachment 1 to TXX-08032 Page 2 of 7 Inherent in the Comanche Peak evaluation of the measured data from the performance of Technical Specification Surveillance Requirement 3.2.1.2 (or any other surveillance) is an assessment of the effects of any deviations between the plant operating state and the conditions assumed in the development of the limit values. These assessments include the potential effects of power level and axial offset. The evaluation of the acceptability of the potential effects of differences between the predicted and measured axial power distribution is based on a comparison with the margin between the total FQ(z), approximated as Fow(z), and the limit value specified in the Technical Specifications (FQ-Limit(z)).
A simple ratio of the predicted steady-state axial power shape (SS-P(z)), used in the development of the transient W(z) curves, and the measured axial power distribution (M-P(z)) is used to evaluate the effect of any differences in the axial power distribution.
Here, M-P(z) is the measured core average axial power distribution at the conditions of the surveillance, obtained from a flux map or from the calibrated BEACON model. The FaW(z), which is FaC(z)* W(z), is multiplied by this ratio. The result is used to confirm that the effects of the difference between the measured and predicted axial power distribution are within the available margins.Presented in another manner: Available FQ(z) margin = FQ-Limit(z) 
-FQw(z) (Eqn. 1)Effect of axial power distribution differences
= FQw(z) * (SS-P(z))/(M-P(z)) 
-FQw(z) (Eqn. 2)If the value calculated in Equation 1 is greater than or equal to the value calculated in Equation 2, the conclusion of the evaluation is that the effects of the differences between the measured and predicted axial power distributions are within the available margins, and Technical Specification Surveillance Requirement 3.2.1.2 is satisfied.
If the value calculated in Equation 1 is less than the value calculated in Equation 2, the conclusion of the evaluation is that the effects of the differences between the measured and predicted axial power distributions are greater than the available margins, and Technical Specification Surveillance Requirement 3.2.1.2 is not satisfied.
The appropriate Actions of Technical Specification would be taken.A numerical example is shown in Tables 1, 2, and 3. Table 1 represents the steady-state axial power shape. Tables 2 and 3 represent axial power shapes with axial offsets that differ by approximately 
-3% and +3% from the steady-state shape. A comparison of the axial power shapes is shown in Figure 1. These shapes (and the corresponding FQ(z) values) were generated with a 3-D nodal code using values under development to support Unit 2 Cycle 11 operation.
The ratio of predicted and measured power shapes effectively corrects the surveilled FQ values for the effects of power shape differences as demonstrated by the adjusted Fa margin values in the accompanying tables. In an actual surveillance, this correction will permit the FQ margin effects of measured Fxy(Z)values to be accurately assessed.
Attachment 1 to TXX-08032 Page 3 of 7 In keeping with standard practice, the W(z) curves will be generated assuming that the surveillance of FQw(z) is performed at full power. Following refueling, FQW(z) must be verified to be within its limit prior to exceeding 75% RTP. Also, FQw(z)must be verified to be within its limits after exceeding, by >20% RTP, the thermal power at which a surveillance was last performed and every 31 EFPD thereafter.
The FQ limit is given by: F Q (z) < [FQRTP / P]
* K(z) for P > 0.5 (Eqn. 3)F Q (z) < [FQRTP / 0.5]
* K(z) forP < 0.5 (Eqn. 4)If a surveillance of FQw(Z) relative to the above limit must be performed at part power conditions, then Equations 1 and 2 will be used as described earlier, where the FQ-Limit(z) term is given by the above expressions (Equations 3 and 4). In this case, however, FQw(z) in Equations 1 and 2 will be calculated as follows: FQW(z) = FQC(Z) * [W(z) / P1 for.P > 0.5 (Eqn. 5)FQW(z) = FQC(z) * [W(z) / 0.5] for P < 0.5 (Eqn. 6)where the W(z) values are the values generated assuming a full power surveillance (i.e., P=1.0). Dividing the W(z) values by P in Equation 5 and 0.5 in Equation 6 ensures that the FQw(Z) terms are increased commensurate with the increase in the FQ limit.Effectively, the P and 0.5 terms scale the measured FQw(z) in the same manner that the Fa limit is scaled to ensure that transient FQ margin will be properly assessed and not overestimated.
Use of these terms is consistent with intent of the definition of the W(z)function presented in WCAP-1 0216-P-A, Revision 1A, which includes a 1/P term to scale FQw(z) in the same manner that the FQ limit is scaled.Alternatively, the BEACON Power Distribution Monitoring System may be used to perform the power distribution surveillance function.
When the surveillance is performed, the BEACON "measured" power distribution is updated to full power, steady state conditions and used to determine the "measured" maximum transient FQ(z) x Power. To do this, the full power "measured" steady state F 0 (z) from the BEACON core model is multiplied by the W(z) curve and the result, FQw(z), is compared to the FQ(z) limit. Thus, the full power W(z) curves are appropriate since the transient FQ(z) measurement is always based on full power conditions.
Differences between the "measured" steady state power shape and the predicted steady state power shape will be addressed as described above (see Equations 1 and 2).Question 2. Explain how CPSES, Units I and 2, will implement the burnup dependency of the W(z) functions, where W(z) represents the largest expected increase in Fq (the heat flux hot channel factor) from allowed plant operation.
Response: The W(z) factors are generated using the approved methods of WCAP-10216-P-A, Revision 1A. Typically, W(z)s are provided at four different burnups to cover the entire operating cycle. A spline fit of the W(z)s versus burnup at each elevation is then used to provide appropriate W(z)s at the burnup of interest.
Attachment 1 to TXX-08032 Page 4 of 7 Table 1: Predicted steady-state axial power distribution with an axial offset of -1.75%CASE AO+O Node Predicted 
=>AO+0 AO+0 AO+0 PsS(Z) FosS(Z) W(Z)Measured->
AO+O AO+O PM(Z) FcM(Z) F 0 c(Z) F~w(Z) K(Z)Limit[F RTP
* K(Z) ]FQ(Z)Margin P(Z) ratio Axial Pwr Dist. Effects[PS(Z) / PM(z) [FaW(Z)
* P(Z) rtio] -FoW(Z)]Adjusted Fa(Z)Margin 0.309 0.424 1.000 0.707 0.973 1.399 0.897 1.210 1.377 1.009 1.374 1.324 1.072 1.469 1.273 1.105 1.516 1.228 1.119 1.540 1.205 1.110 1.540 1.193 1.111 1.546 1.186 1.113 1.554 1.180 1.116 1.562 1.171 1.121 1.573 1.144 1.126 1.585 1.135 1.133 1.599 1.130 1.140 1.613 1.125 1.146 1.627 1.111 1.151 1.639 1.112 1.152 1.642 1.120 1.144 1.632 1.129 1.119 1.596 1.167 1.065 1.510 1.195 0.958 1.347 1.234 0.763 1.085 1.250 0.312 0.433 1.000 0.309 0.424 0.459 0.459 0.928 0.707 0.973 1.052 1.472 0.934 0.897 1.210 1.309 1.802 0.941 1.009 1.374 1.486 1.968 0.947 1.072 1.469 1.589 2.023 0.953 1.105 1.516 1.640 2.014 0.959 1.119 1.540 1.666 2.007 0.966 1.110 1.540 1.666 1.987 0.972 1.111 1.546 1.672 1.983 0.978 1.113 1.554 1.681 1.984 0.984 1.116 1.562 1.689 1.979 0.991 1.121 1.573 1.701 1.947 0.997 1.126 1.585 1.714 1.945 1.000 1.133 1.599 1.729 1.953 1.000 1.140 1.613 1.744 1.962 1.000 1.146 1.627 1.760 1.956 1.000 1.151 1.639 1.773 1.971 1.000 1.152 1.642 1.776 1.989 1.000 1.144 1.632 1.765 1.993 1.000 1.119 1.596 1.726 2.014 1.000 1.065 1.510 1.633 1.951 1.000 0.958 1.347 1.457 1.798 1.000 0.763 1.085 1.173 1.466 1.000 0.312 0.433 0.468 0.468 1.000 2.320 2.335 2.353 2.368 2.383 2.398 2.415 2.430 2.445 2.460 2.478 2.493 2.500 2.500 2.500 2.500 2.500 2.500 2.500 2.500 2.500 2.500 2.500 2.500 1.861 0.863 0.550 0.399 0.360 0.384 0.408 0.443 0.462 0.476 0.499 0.546 0.555 0.547 0.538 0.544 0.529 0.511 0.507 0.486 0.549 0.702 1.034 2.032 1.000 1.000 1.000 1.000 1.000 1.000 i.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 1.861 0.863 0.550 0.399 0.360 0.384 0.408 0.443 0.462 0.476 0.499 0.546 0.555 0.547 0.538 0.544 0.529 0.511 0.507 0.486 0.549 0.702 1.034 2.032 Note that for convenience, the FQ(Z) burnup dependent penalty factor example.(i.e., >= 1.02) has been excluded in this Attachment 1 to TXX-08032 Page 5 of 7 Table 2: Predicted steady-state axial power distribution with an axial offset of +1.71%CASE AO+3 Node Predicted 
=> --AO+0 AO+0 AO+0 PSS(Z) FosS(Z) W(Z)Measured =>AO+3 AO+3 PM(Z) FoM(Z) Foc(Z) Fow(Z) K(Z)Fa"' (Z)Limit[F RTP
* K(Z) ]FQ(Z)Margin P(Z) ratio Axial Pwr Dist. Effects[Ps(Z) / PM(Z) ] [ FoW(Z)
* P(Z) ratio ] -FQW(Z) ]Adjusted FQ(Z)Margin 0 ! 0 ! I 0.309 0.424 1.000 0.707 0.973 1.399 0.897 1.210 1.377 1.009 1.374 1.324 1.072 1.469 1.273 1.105 1.516 1.228 1.119 1.540 1.205 1.110 1.540 1.193 1.111 1.546 1.186 1.113 1.554 1.180 1.116 1.562 1.171 1.121 1.573 1.144 1.126 1.585 1.135 1.133 1.599 1.130 1.140 1.613 1.125 1.146 1.627 1.111 1.151 1.639 1.112 1.152 1.642 1.120 1.144 1.632 1.129 1.119 1.596 1.167 1.065 1.510 1.195 0.958 1.347 1.234 0.763 1.085 1.250 0.312 0.433 1.000 0.317 0.433 0.468 0.468 0.928 0.748 1.028 1.112 1.556 0.934 0.957 1.291 1.396 1.923 0.941 1.075 .1.464 1.583 2.097 0.947 1.137 1.558 1.685 2.145 0.953 1.165 1.600 1.730 2.125 0.959 1.170 1.612 1.743 2.101 0.966 1.149 1.595 1.725 2.058 0.972 1.137 1.583 1.712 2.030 0.978 1.125 1.572 1.700 2.006 0.984 1.116 1.564 1.691 1.981 0.991 1.110 1.559 1.686 1.930 0.997 1.107 1.559 1.686 1.913 1.000 1.107 1.564 1.691 1.911 1.000 1.109 1.572 1.700 1.912 1.000 1.112 1.579 1.708 1.898 1.000 1.114 1.586 1.715 1.907 1.000 1.112 1.585 1.714 1.920 1.000 1.101 1.572 1.700 1.920 1.000 1.076 1.534 1.659 1.936 1.000 1.024 1.453 1.571 1.877 1.000 0.920 1.294 1.399 1.727 1.000 0.726 1.034 1.118 1.397 1.000 0.287 0.397 0.429 0.429 1.000 2.320 2.335 2.353 2.368 2.383 2.398 2.415 2.430 2.445 2.460 2.478 2.493 2.500 2.500 2.500 2.500 2.500 2.500 2.500 2.500 2:500 2.500 2.500 2.500 1.852 0.779 0.430 0.271 0.237 0.272 0.314 0.372 0.415 0.454 0.496 0.563 0.587 0.589 0.588 0.602 0.593 0.580 0.580 0.564 0.623 0.773 1.103 2.071 0.975 0.945 0.937 0.939 0.943 0.948 0.956 0.966 0.977 0.989 1.000 1.010 1.017 1.023 1.028 1.031 1.033 1.036 1.039 1.040 1.040 1.041 1.051 1.087-0.012-0.085-0.121-0.129-0.123-0.109-0.092-0.070-0.046-0.021 0.000 0.019 0.033 0.045 0.053 0.058 0.063 0.069 0.075 0.077 0.075 0.071 0.071 0.037 1.864 0.865 0.550 0.399 0.360 0.382 0.405 0.442 0.461 0.475 0.496 0.544 0.554 0.544 0.535 0.544 0.530 0.511 0.505 0.487 0.548 0.702 1.b31 2.033 Note that for convenience, the FQ(Z) burnup dependent penalty factor (i.e., >= 1.02) has been excluded in this example.
Attachment 1 to TXX-08032 Page 6 of 7 Table 3: Predicted steady-state axial power distribution with an axial offset of -5.18%CASE AO-3 Node Predicted 
=>AO+0 AO+0 AO+0 PSS(Z) F ss(tZ W(Z)RTP Measured => Fa (Z)AO-3 AO-3 Limit PM(Z) F,"(Z) Fnc(Z) Fnw(z) K(Z) [ FrRTP
* K(Z I Fo(Z)Marain P(Z) rtio Axial Pwr Dist. Effects[ Pss(Z) / Pm(z) 1 [ Fow(Z)
* P(Z),.,o I -FoW(Z) 1 Adjusted Fo(Z)Maroin+ ..~ -0.309 0.424 1.000 0.707 0.973 1.399 0.897 1.210 1.377 1.009 1.374 1.324 1.072 1.469 1.273 1.105 1.516 1.228 1.119 1.540 1.205 1.110 1.540 1.193 1.111 1.546 1.186 1.113 1.554 1.180 1.116 1.562 1.171 1.121 1.573 1.144 1.126 1.585 1.135 1.133 1.599 1.130 1.140 1.613 1.125 1.146 1.627 1.111 1.151 1.639 1.112 1.152 1.642 1.120 1.144 1.632 1.129 1.119 1.596 1.167 1.065 1.510 1.195 0.958 1.347 1.234 0.763 1.085 1.250 0.312 0.433 1.000 0.286 0.392 0.424 0.424 0.928 0.677 0.931 1.007 1.409 0.934 0.868 1.171 1.266 1.744 0.941 0.977 1.331 1.439 1.906 0.947 1.037 1.420 1.536 1.955 0.953 1.067 1.465 1.584 1.946 0.959 1.079 1.485 1.606 1.936 0.966 1.069 1.482 1.603 1.912 0.972 1.070 1.488 1.609 1.909 0.978 1.074 1.497 1.619 1.911 0.984 1.081 1.512 1.635 1.915 0.991 1.092 1.532 1.657 1.896 0.997 1.108 1.557 1.684 1.911 1.000 1.127 1.590 1.720 1.942 1.000 1.148 1.625 1.757 1.976 1.000 1.170 1.659 1.794 1.994 1.000 1.188 1.690 1.828 2.032 1.000 1.201 1.711 1.850 2.073 1.000 1.202 1.715 1.855 2.094 1.000 1.185 1.689 1.827 2.132 1.000 1.135 1.609 1.740 2.079 1.000 1.024 1.441 1.558 1.923 1.000 0.812 1.155 1.249 1.561 1.000 0.322 0.446 0.482 0.482 1.000 2.320 2.335 2.353 2.368 2.383 2.398 2.415 2.430 2.445 2.460 2.478 2.493 2.500 2.500 2.500 2.500 2.500 2.500 2.500 2.500 2.500 2.500 2.500 2.500 1.896 0.926 0.608 0.461 0.427 0.451 0.479 0.518 0.536 0.549 0.562 0.596 0.589 0.558 0.524 0.506 0.468 0.427 0.406 0.368 0.421 0.577 0.939 2.018 1.080 1.044 1.033 1.033 1.034 1.036 1.037 1.038 1.038 1.036 1.032 1.027 1.016 1.005 0.993 0.979 0.969 0.959 0.952 0.944 0.938 0.936 0.940 0.969 0.034 0.062 0.058 0.062 0.066 0.069 0.072 0.073 0.073 0.069 0.062 0.050 0.031 0.010-0.014-0.041-0.063-0.085-0.101-0.119-0.128-0.124-0.094-0.015 1.862 0.864 0.550 0.399 0.361 0.382 0.408 0.444 0.463 0.480 0.500 0.546 0.558 0.547 0.538 0.547 0.531 0.512 0.507 0.487 0.549 0.701 1.033 2.033 Note that for convenience, the FQ(Z) burnup dependent penalty factor example.(i.e., >= 1.02) has been excluded in this Attachment 1 to TXX-08032 Page 7 of 7 Figure 1: Power Distributions, PM (Z)1.40 1.20 100 C.. 0.60 0.40 AO+o--------AO+3 0.20 __...AO-3 0.00 0 6 12 18 24 Core Node}}