ML17325A342
| ML17325A342 | |
| Person / Time | |
|---|---|
| Site: | Cook  |
| Issue date: | 10/20/1987 |
| From: | Alexich M AMERICAN ELECTRIC POWER SERVICE CORP. |
| To: | Murley T NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| Shared Package | |
| ML17325A344 | List: |
| References | |
| AEP:NRC:1028, NUDOCS 8710260164 | |
| Download: ML17325A342 (17) | |
Text
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REGULATOR NFORMATION DISTRIBUTION.
TEM (RIDS) k
'DEACCESSION INBR: 8710260164 DOC. DATE: 87/10/20 NOTARIZED:
NO giCIL:.50-,3'lk5'Donald C.
Cook Nuclear Power Plant Unit I, Indiana 5
50'-S~ih Donald C.
Cook Nuclear Power Plantd Unit 2k.Indiana 5
AUTH. NAME AUTHOR AFFILIATION ALEXICHdM. P.
American Electric Poeer Service Corp.
REC IP. NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk)
DOCKET ¹ 05000315 05000316
SUBJECT:
Application for amends to Licenses DPR-58 5 DPR-74d modifying Tech Spec
- 4. i. i. 4 5 associated Bases section to delete requirement to measure moderator temp coefficient (MTC) near end of cycled provided certain MTC. restrictions met. Fee paid.
DISTRIBUTION CODE:
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SIZE: /Q,~ 5 TITLE:
OR Submittal:
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~ If American Electric Power Service Corporation 1 Riverside Plaza Columbus, OH 43215 614 2231000 USHRC-DS B810Ct2b A %50 AEP:NRC:1028 Donald C.
Cook Nuclear Plant Units 1 and 2
Docket Nos.
50-315 and 50-316 License Nos.
DPR-58 and DPR-74 PROPOSED TECHNICAL SPECIFICATION CHANGES FOR MODERATOR TEMPERATURE COEFFICIENT MEASUREMENT U.S. Nuclear Regulatory Commission Attn:
Document Control Desk Washington, D.CD 20555 Attn:
T.
E. Murley October 20, 1987
Dear Dr. Murley:
This letter and its attachments constitute an application for amendment to the Technical Specifications (T/Ss) for the Donald C.
Cook Nuclear Plant Units 1 and 2.
Specifically, we propose to modify T/S 4.1.1.4 and its associated Bases section such that the requirement to measure the moderator temperature coefficient (MTC) near the end of the cycle is deleted, provided certain restrictions on MTC are met.
These changes are requested
- because, we believe we can relax the
'criteria for performing the MTC measurement near the end-of-cycle (EOC) and still ensure the EOC MTC is within its limits.
The 300 ppm MTC measurement is time-and resource-consuming, requiring approximately 60 man-hours of effort each cycle.
Incorporating these changes would allow us to omit the surveillance when we are certain that the EOC MTC limit will not be exceeded.
Our evaluation of data from our previous measurements of MTC in both D.
C. Cook units and information supplied to us by our fuel vendors has led us to conclude that the end-of-cycle MTC test can be safely deleted for both units provided certain conditions are placed on the MTC.
We believe the EOC MTC limit will not be exceeded if the predicted EOC MTC value is at least 5 pcm/ F less negative than the 0
T/S limit and, to show validity of the core design prediction< if the beginning-of-cycle (BOC)
MTC measurement is within 3 pcm/ F of the predicted BOC MTC value.
Attachment 1 to this letter contains further details on our reasons for the proposed
- changes, our technical justification for the
- changes, and our 10 CFR 50.92 significant hazards evaluation.
The proposed revised T/S pages are contained in Attachment 2.
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j AEP:NRC:1028 October 20, 1987 Dr. T.
E. Murley page 2
Among the proposed changes included in this submittal are changes to Unit 1 T/S page B 3/4 1-1 and Unit 2 T/S page 3/4 1-6.
Previous changes to this page were requested in our letter AEP:NRC:0916W, dated March 26, 1987.
These proposed changes are in addition to those proposed in that letter and do not supersede them.
We believe that the proposed changes will not result in (1) a significant change in the types of effluents or a significant increase in the amounts of any effluent that may be released offsite, or (2) a significant increase in individual or cumulative occupational radiation exposure.
These proposed changes have been reviewed by the Plant Nuclear Safety Review Committee (PNSRC) and will be reviewed by the Nuclear Safety and Design Review Committee (NSDRC) at their next regularly scheduled meeting.
In compliance with the requirements of 10 CFR 50.91(b)(1),
copies of this letter and its attachments have been transmitted to Mr. R.
C.
Callen of the Michigan Public Service Commission and Mr. George Bruchmann of the Michigan Department of Public Health.
Pursuant to 10 CFR 170.12(c),
we have enclosed an application fee of
$150.00 for the proposed amendments.
This document has been prepared following Corporate procedures which incorporate a reasonable set of controls to ensure its accuracy and completeness prior to signature by the undersigned.
Sincerely, M.
PE Al xich Vice President pd Attachments cc:
John E. Dolan W.
G. Smith, Jr.
- Bridgman R.
C. Callen G. Bruchmann G. Charnoff NRC Resident Inspector
- Bridgman A. B. Davis
- Region III
Attachment 1 to AEP:NRC:1028 Reasons and 10 CFR 50.92 Analyses for Changes to the Donald C.
Cook Nuclear Plant Units 1 and 2 Technical Specifications
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Attachment 1 to AEP:NRC:1028 Page 1
Descri tion of Chan es This letter proposes to modify D.
C.
Cook Units 1 and 2 Technical Specification (T/S) 4.1.1.4 (Moderator Temperature Coefficient) and, its associated Bases section.
Specifically, we propose to delete the present requirement to measure the moderator temperature coefficient (MTC) within seven effective full-power days of reaching, 300 ppm equilibrium boron concentration, provided certain restrictions on MTC are met.
These restrictions are:
1.
The MTC measured at beginning of cycle (BOC) is within 3 pcm/
F of the predicted value.
0 The end-of-cycle (EOC) predicted value is at least 5
pcm/
F more positive than the T/S limit.
(For Unit 1, 0
the test would be performed if the predicted EOC MTC is more negative than
-30 pcm/ F, while for Unit 2 the 0
value is -34 pcm/ F.)
Back round The T/S 3/4.1.1.4 limitations on moderator temperature coefficient (MTC) are provided to ensure that the value of this parameter remains within the limiting conditions assumed for this parameter in the FSAR accident and transient analyses.
The EOC limits, which are in the negative
- range, are specifically provided to protect against cooldown type accidents such as steamline breaks.
For D.
C.
Cook Unit 1, the EOC limit is
-35 pcm/ F, while for D.
C.
Cook Unit 2 the limit is -39 pcm/ F.
T/Ss require the MTC to be measured at BOC prior to reaching 5%
"of rated power, and again towards the EOC within 7 effective full-power days after reaching 300 ppm steady state boron in the reactor coolant system (RCS).
The surveillance requirement associated with the EOC most negative MTC T/S calls for measuring MTC at any thermal power and comparing with the all rods out hot full-power MTC limit.
The Unit 1 T/S 4.1.1.4 requires the measurement to be extrapolated to the EOC to ensure compliance with the T/S limit.
The Unit 2 T$S requires that this measured MTC be more positive than -30 pcm/ F.
If the measured MTC is more negative than -30 pcm/ F, the MTC measurement must be performed approximately every two weeks for the remainder of the cycle to,ensure that the EOC limit is not violated.
The 300 ppm MTC measurement is time-and resource-consuming.
This surveillance requires approximately 60 man-hours of effort each cycle.
Incorporating these changes would allow us to not perform the surveillance while ensuring that the EOC MTC limit
Page 2
will not be exceeded.
We believe the EOC MTC limit will not be exceeded if the predicted EOC MTC value is at least 5 pcm/
F less negative than the T/S limit and, to show validity of the core design prediction, if the BOC MTC measurement is within 3 pcm/
F of the predicted BOC MTC value.
We have performed evaluations of information supplied to us by our fuel vendors, as well as data from previous MTC measurements of both D.
C.
Cook units.
These evaluations led us to conclude that the EOC MTC test could be safely deleted for both units provided the conditions discussed in the "Description of Changes"
- section, above, were met.
If the specified conditions are not met, our proposed version of T/S 4.1.1.4 will require the 300 ppm MTC test to be performed.
The condi,tions listed above were based on evaluations which we performed.
These evaluations involved a review of:
1.
the theoretical basis of the change in MTC over the length of a cycle, 2.
past results of MTC tests, and 3.
acceptance criteria used during startup tests.
Each of these evaluations is discussed below.
1.
Evaluation Based on MTC Theor The moderator temperature coefficient is defined as the change in reactivity per degree change in the moderator temperature.
An increase in moderator temperature reduces the moderator density and results in less moderation.
This effect introduces a negative component in the moderator temperature coefficient.
The soluble boron used in the reactor as a means of reactivity control also has an effect on the moderator temperature coefficient, because the soluble boron concentration as well as the water density is decreased when the coolant temperature rises.
A decrease in the soluble poison introduces a positive component in the moderator temperature coefficient.
With burnup the moderator temperature coefficient becomes more negative primarily as a result of the reduced boron concentration.
It also tends to become more negative, to an extent, as a
direct result of burnup effects such as the buildup of plutonium and fission products, which results in a hardening of the neutron spectrum.
Design calculations show that the EOC MTC at 0 ppm for the longest D.
C.
Cook cycle (Unit 2, Cycle 3) was not more
Page 3
negative than -31 pcm/ F.
Data from the fuel vendors for the current cycle show the effect of burnup alone on MTC to be approximately 0.4 pcm/ F/1000 MWD/T.
In other words, the burnup would have to be increased by approximately 10,000 MWD/MTU beyond 0 ppm for current cycle designs in order to attain an MTC of -35 pcm/ F.
For Unit 2, Cycle 3 such an increase in burnup would have resulted in a cycle burnup of approximately 27,000 MWD/MTU.
The usual cycle burnup ranges are from 15,000 MWD/MTU to 19,000 MWD/MTU.
The predicted EOC burnup for Unit 1, Cycle 9 is 15,750 MWD/MTU, and for Unit 2, Cycle 6 it is 17,890 MWD/MTU.
Therefore, there exists a substantial margin between the EOC calculated MTC and the EOC limit on MTC.
A significant increase in burnup would be required to eliminate this margin.
- Thus, theoretical considerations would support eliminating the EOC MTC test for cycle burnups attainable in the foreseeab~
future.
2.
Evaluation of Previous MTC Tests In order to establish a bound on the error in predicted versus actual values for the MTC, the most recent Unit 1 and all Unit 2 measurements were reviewed.
Table 1 displays the BOC MTC test
- results, while Table 2 displays the 300 ppm test results.
To enhance measurement
- accuracy, several measurements of the MTC were taken as part of each test.
The data in Tables 1 and 2 represent the average of these individual 'measurements.
The worst deviation in the 300 ppm data for all the cycles evaluated was seen in Unit 1, Cycle 6.
This deviation was in the conservative direction and had an absolute value of 0
5.1 pcm/ F.
The worst deviation in the nonconservative direction for the 300 ppm test was a deviation of 2.08 0
pcm/
F found in Unit 1, Cycle 7.
Our proposed revision of T/S 4.1.1.4 would require us to perform the 300 ppm test if the predicted EOC MTC value is 0
0 more negative than -30 pcm/
F for Unit 1 or -34 pcm/
F for Unit 2.
The worst-case deviation between predicted and 0
measured values of 5.1 pcm/
F might at first glance appear inconsistent with respect to the 5 pcm/
F condition we have 0
proposed.
However, it must be realized that the deviations noted in Tables 1 and 2 include measurement errors as well as calculational errors.
In order to establish an upper bound on the error inherent in the predicted value alone, we have performed a statistical evaluation of past MTC test results.
The statistical evaluation concluded that the error in the gredicted value of the MTC would be no greater than 4.9 pcm/ F at a 95% level of confidence.
Our proposal to perform the MTC test if the EOC predicted value is not at least 5 pcm/
F more positive than the T/S limit is conservative with respect to the value of 4.9 pcm/ F
I
Page 4
obtained from the statistical evaluation.
A summary of the statistical evaluation follows.
Summar of Statistical Evaluation The deviation between the predicted and measured values of the MTC (delta columns of Tables 1 and 2) is obtained as follows:
Delta - (Predicted Value of MTC) - (Measured Value of MTC)
The deviations between the calculated and measured MTC values were assumed to be normally distributed.
Also, the deviations between the calculated and actual and the measured and actual values were taken to be independent, since the test method is the same regardless of the calculational methodology.
With the above assumptions, the standard deviations are related as follows:
2 a D where 2
2 a
standard deviation of the difference D
between predicted and measured values of MTC.
gM - standard deviation of the difference between the measured value of MTC and actual MTC value.
g - standard deviation of the difference P
between the predicted value of MTC and actual MTC value.
By rearranging Equation (1), the knowledge of cD and o
- Thus, 2
2 2
ap aD aM Qp can be obtained from (2)
Equation 2 was used to obtain estimates of the error in the predicted value of the MTC ~
Conservative estimates were obtained for the BOC data and the 300 ppm data.
'The conserv-ative estimate of 4.9 pcm/ F, obtained from the 300 ppm
- tests, was used in the proposed version of the T/Ss.
The estimates were made by first obtaining a conservatively high o at a 95$ confidence level, using the Chi-square statislical distribution with the data from Tables 1 and 2.
(The data from Units 1 and 2 was blended in the statistical evaluations we performed.)
A conservatively low value for was estimated at a 95% confidence level using the Chi-M square distribution with data from the individual measure-ments of MTC taken as part of each test.
(As noted earlier,
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several measurements of the MTC were made for each test and then averaged to obtain the values listed in Tables 1 and 2.)
Finally, the value of <
obtained from Equation 2 was used to P
obtain a conservatively high estimate of the error in the predicted value at a 95% level of confidence.
The bounding calculational errors obtained through the very conservative method discussed above are 3.3 pcm/
F for the BOC data and 4.9 pcm/ F for the 300 ppm data.
One of our fuel vendors, Westinghouse Electric Corporation (Westing-house),
informed us that the acceptance criterion for the 0
BOC is equal to + 3 pcm/
F (see next paragraph).
Because this acceptance criterion includes both calculational errors and measurement
- errors, we can say that Westinghouse's calculational error is less than 3 pcm/ F.
The other fuel 0
- vendor, Advanced Nuclear Fuel Company, informed us that their calculational error for BOC is equal to + 2 pcm/ F ~
Our estimate of 3.3 pcm/
F calculational error for the BOC is higher than the vendors'alues and thus gives us con-fidence that our statistical method yielded conservative results.
Evaluation Based on Acce tance Criteria Used Durin Startu Tests From Table 1, it is seen that the deviation between calcu-lated and measured MTC values seen at BOC has been well within 3 pcm/
F..
A value of + 3 pcm/
F for the BOC MTC was 0
0 recommended by Westinghouse Electric Corp.
as an acceptance criterion for D.
C.
Cook Unit 1 startup in the document "Donald C.
Cook Nuclear Plant Unit No.
1 Startup Physics Tests Acceptance Criteria, August 1974."
We believe that a BOC MTC within 3 pcm/ F of the predicted value indicates that the MTC predictions are accurate and provides some degree of confidence that EOC values of MTC will be accurate.
(This conclusion is supported by the statistical evaluation provided in Section 2, above.)
- Thus, we have proposed as one of our conditions for not performing the 300 ppm MTC test a
BOC MTC within 3 pcm/
F of the predicted value.
Per 10 CFR 50.92, a proposed amendment will not involve a signif-icant hazards consideration if the proposed amendment does not:
(1) involve a significant increase in the probability or consequences of an accident previously evaluated, (2) create the possibility of a new or different kind of accident from any previously analyzed or evaluated, or (3) involve a significant reduction in a margin of safety.
Attachment 1 to AEP:NRC:1028 Page 6
Criterion 1 We have presented analyses which demonstrate that the error in the gredicted value of MTC is expected to be no more than 5
pcm/ F at a 95% level of confidence.
Consistent with this, we propose to perform the MTC test if our predicted value of MTC at EOC conditions is not at least 5 pcm/ F less negative than the 0
T/S limit.
We have, as an additional measure, proposed to perform the MTC test if the BOC data deviates from the BOC predicted value of MTC by more than 3 pcm/ F.
We believe, based on our. evaluations detailed
- above, that the MTC test at 300 ppm can be safely deleted provided that the conditions previously discussed are met.
Therefore, we conclude that our proposed T/S change will not involve a significant increase in the probability or consequences of a previously analyzed accident, nor will it involve a significant reduction in a margin of safety.
Criterion 2 Our evaluation has demonstrated reasonable assurance that T/S limits will not be exceeded if the 300 ppm MTC test is deleted, provided certain conditions for the deletion are met.
- Thus, we believe all nuclear design bases will continue to be met and therefore conclude that the change should not create the possi-bility of a new or different kind of accident from any previously analyzed or evaluated.
Criterion 3 See Criterion 1, above.
- Lastly, we note that the Commission has provided guidance con-cerning the determination of significant hazards by providing certain examples (48 FR 14870) of amendments considered not likely to involve significant hazards consideration.
The sixth of these examples refers to changes which may result in some increase to the probability or consequences of a previously analyzed accident or may reduce in some way a safety margin, but the results of which are within acceptable limits.
The proposed change is similar to this example in that T/S requirements are being deleted, but the deletions are supported by evaluations which demonstrate that applicable T/S limits will continue to be met.
The fourth example refers to changes that involve relief granted upon demonstration of acceptable operation from an operating restriction that was imposed because acceptable oper-ation had not yet been demonstrated.
Our proposed change is similar to this example in that our predicted values of MTC obtained over numerous cycles have been shown statistically to be
- accurate, and therefore support deletion of the 300 ppm MTC test requirements Based on the above discussion, we believe the examples cited are relevant and thus support our conclusion that the proposed change should not require significant hazards consideration.
I I
Table 1
BOC MTC TEST RESULTS Unit 1 Unit 2 Cycle Meas.
(Design-Design Meas.)
Cycle Meas.
(Design-Design Meas.)
1.89 3.85 3.79 3.53 3.10 1.21 2.26
-1.59 2.40
-1.39 4.16 0.63 1.30 0.71 4.19
-0.98 0.50 0.15 3.25 1.48
-0.80
-0.56
-0'4 2.46 2.79 4.10 2.37 2.15
-0.42
-1.95 2.4 2.46 3.10 3.17 0.70 0.71
Table 2
300 PPM MTC TEST RESULTS Unit 1 Unit 2 Cycle Meas.
(Design-,
Design Meas.)
Cycle Meas.
(Design-Design Meas.)
-20.80
-20.2 0.60
-17.16
-16.8
-14.39
-19.09
-1
~ 93
-19.5
-2.7
-19.51'5.12 2'8
-21.37
-19.29
-19.99
-25.38
-20.27
-17.66
-20.5
-26.70
-23.3
-20.5
-18.23
-21.0
-2.77
-0.51
-1.32
-3.03
-2.84
-22.7
-25.4
-21.8
-24.0'.9 1.4
Attachment 2 to AEP:NRC:1028 Proposed Revised Technical Specification Pages