ML20044B287
| ML20044B287 | |
| Person / Time | |
|---|---|
| Site: | Braidwood  |
| Issue date: | 07/09/1990 |
| From: | Hunsader S COMMONWEALTH EDISON CO. |
| To: | Murley T NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM), Office of Nuclear Reactor Regulation |
| References | |
| RTR-NUREG-1002 0516T, 516T, NUDOCS 9007180292 | |
| Download: ML20044B287 (4) | |
Text
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Y Commonwealth Edison :
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) 1400 Opus Pisce J
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) Downers Grova, Illinois 60515 L~
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i June 29, 1990 (Reissue dated July 9. 1990-to correct letter date)
Dr. Thomas E.- Murley, Director Office'of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, DC 20555
'Attu:
NRC Document Control Desk Subjects Braidwood Unit 2
- Initial Use of Rod Worth Measurement l
Using the Rod Exchange Technique l.
NRC _ Dockett_End.Q-M7 Reference (a): NUREG-1002, Safety Evaluation Report Supplement 2, dated October, 1986 Section -4.3.2 of: Reference (a) provided the NRC evaluation which -
allowed Braidwood Station to use the Rod Exchange method to measure the worth
.of Rod Control-Cluster Banks. Condition (4) of Section 4.3.2 of reference.(a) requi1ren' that "...a report. comparing the measured and predicted rod worths will be submitted to the NRC within 45 days of the completion of the rod worth
. tests for-the first use of red swap of a reload at each unit." The purpose of this letter is to respond to this requirement.
Attachment A provides a brief description of the calculations performed in accordance with the Braidwood Station procedure used to make the rod worth measurements. Table'1 of attachment A summarizes tha results obtained.'
This'information is being provided for NRC review.
Please address any questions regarding this submittal to this office.
Very truly yours,
,dC. %A S.C. Ilunsader Nuclear Licensing Administrator cc:
S.P. Sands-NRR W.'Shafer-RIII BWD Resident Inspector i'
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L, ATTACIBGENT A i
1
+,
y a-h Braidwood Unit 2, Cycle 2 Eero Power Physics Tosci.'g M Worth Measur nt Results
[
i
-The purpose of this test was to determine the differential and t
integral-worth of the reference bank over its' entire travel in an unrodded core and to-determine the integral worths of.the remaining l>
banks using the rod eshange method.
Adequate shutdown margin exists based on the rod worth measurements meeting the required acceptance
. criteria..
.The rod exchange technique required calculations by Nuclear Fuel f
Services-(Reference 2) providing estimated critical positions of-the I
-reference bank'after exchange with the bank being measured, i
P h, and the associated correction factors, m,.-
The measurements were E
obtained for three reference bank positions a)
Initially fully inserted position, (h I o b)
Critical. posit'.on after exchange h) c)-
Final'ful',y inserted position, (h I o I
The worth of r. measured bank, y, 1st I
=w
- (AP ),
"* W )x 1
2 where 1)-
M = The total measured worth of the reference bank.
y R
2)
(Ap2}x = The reference bank worth from o steps to the M Initial M Return average of (ha)o and (h )o a
3)
(Ap )
= The reference bank worth from hg to 228 2
steps.
1 28(060890)ZD79G
4) ef.oAcart:cticsfcetsrfar'th3h(worthdu) w; 1
to th) g rodded geometry.
Rod worth measurements were performed under the guidance of Westinghouse' Rod' Exchange topical (Reference 3).
The document states that the allowable percent difference between measured and l
predicted reference bank worth is 10%, 15% for individual rod banks-and 10% for the sum of all measured rod banks.
For individual banks l
with a predicted worth less than 667 pcm the allowable difference is
/-.
100 pcm rather than 15%.
The worth of reference bank (CBC) was measured by dilution. The percent difference between the predicted worth and the measured q
worth by dilution of CBC was determined to be -3.2%, which is well within the allowable limits as stated above.
The results of the rod.
worth measurements based on the dilution measurement of CBC are shown-in Table-1.
y l
y, Using the rod exchange technique, all control and shutdown banks l-were eschanged with CBC.
The largest percent difference between.a
~
i measured and predicted rod worth was -10.4% for Control Bank-A.
b Since~the. predicted worth of CBA was 446 pcm (< 667 pcm) the y
allowable difference was 100 pcm.
The largest difference between a i
l'-
measured-and predicted rod worth in pcm was -55.6 pcm for Shutdown Bank E.- This value is below the allowable difference of 100 pcm.
The measured total worth of all banks, based on dilution i
measurements of CBC, was 5012.3 pcm which differs by -1.6% from the predicted worth.
All safety and design acceptance criteria were met.
2 28(060890)ZD79G
E diI I s
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~
ATTACIBGENT A - TABLE 1
+
ROD rrrw4NGE MEASUREMENTS I
L DILUTIGE BRAIDNOOD UNIT 2, CYCLE 2 t
t Reference Reference Bank Bank -'
Inferred Predicted Percest MitMrawn North North Difference M
BANK Inserted (h,),(steps)
.g g
(Apg),
(4 )x "x M )x "x
I h,.
a 2
2 l
No.
ID Initial Return Average (steps) x (pcm)
(pcm)
(pcm)
'(pcm)
, pcm)
(%)-
(
1 C
901.6 931
-3.2 2
D 22 22
- 22 146' 1.08 14.3 355.7 384.2 503.1 503 0.0
(
3 8
22 22 22 196.5 1.28 14.3 160.2 205.1 682.2 669 2.0 l
4 A-22 22 22 95 0.91 14.3 535.9 487.7 399.6 446
-10.4 5
SD 22 22 22 130.5' 1.09 14.3 404.1 440.5 446.8 428 4.4 6
SC 22 22 22 130 1.09 14.3 405.8 442.3
-445.0 428 4.0 7
SB 22 22 22 208 1.01 14.3 82.2
.83.0-804.3 830-
-3.1 l
l 8
SA 22 22 22 99 1.10 14.3 519.1 571.0 316.3 289 9.4' 9
SE 22 23 22.5 130 0.92 14.9 405.8 373.3 513.4 569
-9.8 M
Measured Integral Reference Bank North, Ng=
901.6 (pcm)
Total
-5012.3 5093.0
-1.6 I
M Calculations:
N, = NE - Ihl) - "x k 2}x I
I P
P Percent Difference = (N,
- N,)/N, x100 Note: Predicted values from Reference 2.
3 28(060890)
ZD79G