ML20006A164

Forwards Info Describing Initial Use of Rod Worth Measurement Using Rod Exchange Technique,Per Sser 2 (NUREG-1002)

ML20006A164
Person / Time
Site:	Braidwood
Issue date:	01/11/1990
From:	Hunsader S COMMONWEALTH EDISON CO.
To:	Murley T Office of Nuclear Reactor Regulation
References
RTR-NUREG-1002 NUDOCS 9001250391
Download: ML20006A164 (5)

Text

Commonwealth Edison One First Nationa1 Plan Chicato Illinois A33ress Reply to: Post Offee Box 767-aChicago, Illinois 60690 0767 January 11, 1990 Dr. Thomas E. Murley, Director Office of Nuclear Reactor Rei;ulation U.S. Nuclear Regulatory Commission Washington, DC 20$$$

Attn NRC Document Control Desk

Subject:

Braidwood Unit 1 Initial Use of Rod Worth Measurement Using the Rod Exchange Technique NRC Docket No. 50-456 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) requires 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 rod 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 the results obtained.

This information is being provided for NRC review. Please address any questions regarding this submittal to this office.

Very truly yours, wb S.C. Hunsader Nuclear Licensing Administrator cc S.P. Sands-NRR W. Shafer-RIII BWD Resident Inspector 0516T/SCII:wj i

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+' ATTACHMENT A'

... l, Braidwood Unit 1, Cycle 2 f Zero Power Physics Testing I i

1

. Rod worth Measurement Results- i f

The purpose cf this test was'to determine the differential and integral worth-

[

-i of the reference bank over its entire travel in an unrodded core and to determine  !

a the-integral worths of the-remaining banks using the rod exchange method.

-[

t

-Adequate shutdown margin' exists based on the rod worth measurements meeting the required acceptance criteria. .

[

e The rod exchange technique required calculations by Nuclear Fuel Services E

(Reference 2) providing estimated critical positions of the reference bank i after exchange with the bank'being measured, h , and the associated correction' factors, o( ,. The measurements were obtained for three reference bank positions:

a) Initially fully inserted position, (h")"f'"

b) Critical position after exchange, h c) Final fully inserted position, (h ), .

The worth of a measured bank, W , ist f

W= p( x( Af2 }x

- (Af y)x '

where:

. = The total measured-worth of the reference bank.

2) ( Af y)x = The reference bank worth' from .0 steps to the

~

average of'(h ) " and (h ) Return

3) . ( Af 2}x = The reference bank worth f rom h to 228--

steps.

4) o( = A correction factor for the h worth due to the rodded

• geometry. e i

.i

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t

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• worth measurements were performed under the. guidance of' Westinghouse i

Rod Exchange topical (Reference 3).. The document states that the allowable.

porcent difference between measured and predicted reference-bank worth is lot, 154 for individual rod banks and lot for the sum of all measured rod banks. For individual banus with a predicted worth less'than 600 pcm the' f allowable difference is 100 pcm rather than 15%.

i The worth of reference bank (CBC) was measured by dilution. 'The percent difference between the predicted worth and the measured worth by dilution- f of CBC was determined to be -6.2%, which is well within the allowable I i

limits as stated above.- The results of the rod worth measurements based [

i on the dilution measurement of CBC are shown in Table 1. t Using the rod exchange technique, all control and shutdown banks were exchanged [

l with CBC. The largest difference between a measured and predicted rod worth

{

, was -12.86% for Shutdown Bank E. Since the predicted. worth of CBC was 916= 7 l

I pcm (> 600 pcm) the allowable dif ference was 15%. The measured total worth. t l

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of all banks, based on dilution measurements of CBC, was 4564.5 pcm which l t i differs by -7.23% from the predicted worth. All safety and design acceptance  !

criteria were met. 1 i

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ATTA09ENT A TABLE 1

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ROD EMOUWeGE MEASURDENTS t

DILUTI(Ni 4

fr?As cu re. o Unit 1, Cycle 2 Reference Reference Bank Bank Inferred Predicted Percent BMK Inserted (4),(etope) Withdrawn North worth Difference

hM

• x (4 1) (M2) "m(M2 ):, "m #!

us. _ID Initial neturn Averego (stepe)__ (pen) (pen) (pen) (pen) (pcm) (t) 1 - - - - - - -

CBC -

759.E. 9/6 - (, . 20 a cip 3

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20 10 20 154 1-13 15.42 2G4.oo 24T32 545.6 SGf -3.i9 CBB zo Iy 19 iV4 _ 12

f. 13.97 Il5.2.o 19.o z. '16. 2. 757 - 5.64 0 36 CBA 115 19 / F.5 0.9 E 13.24 553 74 Si4.oG 3%9 35/ -5 46 5 SBE 19 l? If 'l3 o '!8 13.?F 517.43 507.02 338.I 377 -12 2 0 l.of 45530 4962f SB) 19 19 If IOG 13 9T 341.9 syy - 9.13 7 SBc 19 2o If.5 107 1 09 14.70 4 50.70 41/.ZG 353.2 33+ _ -3.o1 U 2.lG

GBB 1o 19 19.S O.98Ll4go 12.SG 22.11 %22.4 902 -1 13

• SBA / F.5 Y7 537-70 514.F5 -7 42 19 17 l 10 b2G 149./ 271 Measured Integral Reference Bank North, % = D (pcm) Total 46608 4 920.0 "7.23 i

Calculatione: W,I = $ - (4 )

1 * ,(4 3m2 PercentDifference=(W[-W{)/W[m100 i Note: Predicted values from Reference 2.

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REFERENCES'

1. : NRC letter V. S. Noonan to D. L. Farrar, daten ':eptember 9, 1986.

SUBJECT:

Byron /Braidwood Rod swap. Technique

2. - CECO. Letter BRIC2/042. Ronald J. Chin _to D. E. O'Brien, dated November

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14, 1989.

FUBJECT: Braidwood.1, Cycle 2 Rod Exchange Data.

=3. WCAP-9863-A, " Rod Bank Worth Measurements Utilizing Bank ~ Exchange", dated' May, 1982.

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