ML20085K316
| ML20085K316 | |
| Person / Time | |
|---|---|
| Site: | Dresden, Quad Cities, 05000000 |
| Issue date: | 07/02/1974 |
| From: | Abel J COMMONWEALTH EDISON CO. |
| To: | Goller K US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| NUDOCS 8310200385 | |
| Download: ML20085K316 (1) | |
Text
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m P One First Nabonal Plata Chicago, lihnois AddnReply to: Post Olhce Box 767
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July 2,1974 i l%
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3 Mr. K. R. Goller
/l Assistant Director for Operating Reactors Directorate of Licensing g-Of fice of Regulation
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U.S. Atomic Energy Commission N
Washington, D.C.
20545
Subject:
Dresden Unit 3 Inverted Control Rod Tubes, AEC Dkt 50-249
Dear Mr. Goller:
As indicated in a letter to D. J.
Skovholt dated October 11, 1973 concerning this subject, the control blades at Dresden Unit 3 were checked for inverted tubes during the spring 1974 refueling outage.
The attached report, entitled " Control Blade Inspection and Evaluation," summarizes the checks performed and the results.
On the basis of the results and evaluations discussed in the attached report, all special requirements and testing discussed in letters to D.
J. Skovholt dated October 11 and 31,1973 relative to inverted control blade tubes have been discontinued for Dresden Unit 3.
Your approval is requested to discontinue at Dresden Unit 3 the three (3) actions required in the letter from D.
J.
Skovholt dated April 1, 1974.
As discussed on Page 4-2 of the attached report, the effects of the remaining inverted control rod tubes are negligible relative to (1) rod drop accidents, (2) pressurization transients, and (3) accuracy of predicted shutdown margins.
The requirements of the April 1, 1974 letter will be met until approval to discontinue is received.
One (1) signed original and 39 copics of this report are submitted for your review.
Very truly yours,
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PDR S. Abel Nuclear Licensing Administrator Boiling Water Reactors f\\
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Commonwealth Edicon ll$)' :
one First Na l Plaza. Ch cago. 11.nois
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Address R - o: Post O'hce Box 767
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Chicago, lik 60650 A-October 11, 1973
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R E C EIV E D $'
I Mr. D. J.
Skovholt z
Assistant Director for Z
OCT 151973 Operating Reactors Directorate of Licensing 9
U.S. Aro.,ic Energt conminion Office of Regulation Re:;ulatory U.S. Atomic Energy Commission 4<
Mail secnon Washington, D.C.
20545 A
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Subject:
Dresden Units 2 and 3, Quad-Cities Units 1 and 2 - Inverted 1 Rod Tubes -
AEC Dkts 50-237 ] -249, 0-254 and 50-265 I
Dear Mr. Skovholt:
In response to your letter dated September 5,
- 1973, the following information concerning our program for possible inverted control rod tubes is supplied.
Your letter indicated six specific items of concern.
Our response to Items 4 and 5
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is attached.
Completed answers to Questions 1, 2, 3 and 6
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by October 31, 1973.
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c.. wt Questions 1 and 2 of your letter involved information
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concerning possible extent and effect of loss of negative reactivity due to inverted control rod tubes.
These questions f %QQ
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e docket and the answers in that report are generally applicable j
Y to the Dresden and Quad-Cities units.
The specific answers for
[ddh).kh Dresden and Quad-Cities, expected to be submitted by October 31,
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1973, will include consideration of the higher shutdown margins which exist at our plants compared to Millstone.
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Very truly yours,
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Nuclear Licensing Administrator -
Boiling Water Reactors j y.
4 Att.
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ATTACID1ENT Control Blade - Response to the AEC (4)
Surveillance requirements to maintain adequate shutdown reactivity margins and monitor changes in poison distribution.
A significant amount of operation allowing for compaction of boron has accrued, and in addition, a recent demon-stration of 1%z1K/K margin for each control blade was performed on all 4-800 MW EWR's.
A monthly equivalent reactivity anomaly check is performed and a planned check of all blades during the forthcoming refueling outages obviate the need for an extensive amount of surveillance.
However, in order to provide additional assurance during the remainder of the present operating cycles, a 15z1K/K margin check for two or more selected rods and a local critical check will be performed for any unit (D2, D3, longer ou)tage).in the cold Xenon free condition (72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or QC1, QC2 Additionally, for each startup following a 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> outage during the remainder of the present operating cycles, the control rod pattern at the time of achieving criticality will be recorded and evaluated.
Anomalies of 1GoK/K or more will be reported as an abnormal occurrence and significant deviations of less than 1% AK/K will be reported as an unusual event (30 day letter).
(5)
Plans and schedules for changeout of control rods.
Commonwealth Edison Company will check all of the control blades in Dresden 2 and 3 and quad Cities 1 and 2 by using a detector (probably an eddy current device used by General Electric) to check for the steel wood packing in the tubes which should be at the bottom of the tubes.
Any blades, sheaths or tubes found to be inverted will be reported to the AEC at the completion of the checking program for each unit.
Any control blade with a significant number of inverted tubes will be replaced.
Commonwealth Edison Company plans to -accomplish the checking and any necessary replacement of blades during the forthcoming schedulec refueling outage for each unit and in any event within two refuelin'g outages.
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4 UNITED STATES pl-
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/5 ATOMIC ENERGY COMMISSION
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W ASH I N GTON. D.C. 20545 l
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! syn et SEP 5 1973 iM' Docket Nos. 50 7
.A"4 249 50-254' k
and 50-265 3:.+
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.W Commonwealth Edison Company gf[?..
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ATTN:
Mr. Byron Lee, Jr, President Post Office Box 767 y;4
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Chicago, Illinois 60690
.$.' 4 Gentlemen:
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You were informed by the Regional Director of Regulatory Operations on fgl.%
July 26, 1973, of the possibility that your control rods fabricated g..g 44..
by the General Electric Company may have inverted poison tubes. You Myikf.3 have completed requested shutdown reactivity margin measurements to assure an adequate shutdown margin existed at the time cf the measure-M fq y ments. We are continuing our review of this occurrence and have con-
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cluded that insufficient data exists to conclude that further poison
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redistribution cannot occur. Therefore, you are requested to submit
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the following information for our review:
(1) analyses of possible M. s length and location of poison voids which could be caused by boron tgD7 carbide redistribution, (2) the effect of such redistribution on normal operation, transients, and accidents, (3) proposed changes to technical specifications which will assure that all safety margins stated or implied in your FSAR are maintained, (4) surveillance require-ments to maintain adequate shutdown reactivity margins and monitor changes in poison distribution, (5) your plans and schedules for changeout of control rods, and (6) expected curve of reactivity vs burnup for remainder of current operating cycle.
Copies of the " Reactor Control Blade Evaluation" special report and supplement submitted by The Millstone Point Company along with our l
reply and safety evaluation are enclosed to serve as guidance in the preparation of your submittal. It is requested that any proposed 4_ 4 o, 3ra COPY SENT PIgro3"[
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s Commonwealth Edison Co=pany SEP 5 PJ73 changes within your Technical Specifications to account for poison redistribution in inverted poison tubes be implemented upon submittal pending completien of our review of your proposed changes. Your response is requested within 30 days as three signed and thirty-seven additional copies.
Sincerely, g
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tonald J/ kovholt Assistant Director for Operating Reactors Directorate of Licensing 1
Enclosures:
1.
Millstone ltrs dtd 7/23 6 7/26/73 transmitting Reactor Control Blade Evaluation and Supplement 2.
AEC ltr to Millstone dtd 7/27/73 and Safety Evaluation ec w/ enclosures:
Mr. Charlem Whitmore President and Chairman Iowa-Illinois Gas and Electric Company John W. Rowe, Esquire Isham, Lincoln & Beale Counselors at Law Morris Public Library Moline Public Library