ML20245C671
| ML20245C671 | |
| Person / Time | |
|---|---|
| Site: | Byron, Braidwood, 05000000 |
| Issue date: | 04/21/1989 |
| From: | Chrzanowski R COMMONWEALTH EDISON CO. |
| To: | Murley T Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20245C675 | List: |
| References | |
| NUDOCS 8904270331 | |
| Download: ML20245C671 (5) | |
Text
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f 1 r/[ Comm:nw:cith Edison
+
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72 West Adams Street, Chicago. Illinois '
ci r.
Address Reply toiPost OfficeBoT77
( */. Chicago, Illinois 60690 0767 w
April 21,'I'989
.Dr. Thomas E. Murley, t'irector Office of Nuclear Reactor F6gulation U.S. Nuclear Regulatory Commission
-Washington, DC 20555
Subject:
Byron Unit 2 Rod Swap Technique EltC Docket No. 50-45]i References (a) September 9, 1986, letter from V.S. Noonan-to D.I..
Farrar Dear-Dr. Murley Commonwealth Edison (CECO) requested to use the rod swap technique and the CECO nuclear. analysis methods in support of control rod worth measurements-for Byron and.Braidwood Stations. Reference (a) conditionally approved the request. The attachment to this letter satisfies condition (4) with the submittal of the report comparing measured and predicted rod worths for the first use of rod swap during the. Byron Unit 2 refueling' outage.
Please direct any questions.on this matter to this office.
Very truly yours,
. OW R.A. Clrzanowski Nuclear Licensing Administrator A
/sc1:0094T 1 cc: Resident Inspector-Byron L.N. Olshan-NRR Region III Office 8904270331 spo423 r
DR ADOCK 0500045s p~
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ATTACHMENT A Byron Unit 2, Cycle 2 Zero Power Physics Testing Rod Worth Measurement Results l'
l The purpose of this test was to determine the differential and integral worth of the reference bank over its entire travel'in an unrodded core and to determine.the integral worths of the remaining banks using the rod exchange method. Adequate shutdown margin exists based on the rod j
worth measurements meeting the required acceptance criteria.
l The rod exchange technique required calculations by Nuclear Fuel Services (Reference 2) providing estimated critical positions of the P
reference. bank after exchange with the bank being measured, h,,'and the associated correction factors, a,.
The measurements were obtained for three reference bank positions:
a)
Initially fully inserted position, (h )
M b) Critical position after exchange, h, c) Final fully inserted position, (h )
- I The worth of a measured bank, W, ist
- (Ap )
- a (Ap )
W =
where:
1)
= The total measured worth of the reference bank.
2)
(Ap ), = The reference bank worth from 0 steps to the g
average of (h )
and (h )o* "#".
xo x
3)
(Ap )x = The reference bank worth from h to 228 2
steps.
M
- 4) a = A correction factor for the h worth due to the rodded geometry.
(1517M/C180M)
l 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 predicted reference I
bank worth is 10%, 15% for individual rod banks, and 10% for the sum of.
all measured rod banks.
For individual rod banks with a predicted worth less than 600 pcm the allowable difference is 100 pcm rather than 15%.
The reference bank, control bank C (CBC), was measured by_boration and dilution. The percent difference between the predicted worth and the measured worth by dilution and boration of CBC was determined to be
-3.9% and -2.9%,
respectively, which are both well within the allowable limits as stated above. The results of the rod worth measurements are shown in Tables 1 and 2..
Table 1 is the measured rod worths based on the dilution measurement of CBC and Table 2 is the measured rod worths based on the boration measurement of CBC.
Using the rod exchange technique, all control and shutdown banks were eachawjed with CBC.
The largest difference between a measured and predicted rod bank worth was based on the rod exchange results using the dilution data of CBC and was -18.4% for Shutdown Bank A (255.5 pcm).
Since the predicted worth of SBA was 313 pcm (< 600 pcm) the allowable worth difference was 100 pcm.
All other rod worth measurements were within the allowed 15% difference. The measured total worth of all banks, based on the average of dilution and boration measurements of CBC, was 4818.0 pcm which differs by -6.7% from the predicted worth.
All safety and design acceptance criteria were met.
1 i
(1517M/0180M)
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