ML19345A689
| ML19345A689 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 08/07/1972 |
| From: | Vandenburgh D YANKEE ATOMIC ELECTRIC CO. |
| To: | US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| NUDOCS 8011240558 | |
| Download: ML19345A689 (4) | |
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YANKEE ATOMIC ELECTRIC COMPANY 20 TURNPIKE ROAD.WESTBORO, MASSACHUSETTS 01581 TELEPHONE 617 366 9011 August 7, 1972 Regulatory po;py 3-b5 p.%
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United States Atomic Energy Commission g ;. m
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Attention: Directorate of Licensing t'[)
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Reference:
License No. DPR-3 (Docket No. 50-29) 16 g \\ 0 w'
Dear Sirs:
During the control rod drop time surveillance test on July 29, 1972, Yankee Atomic Electric Company experienced difficulty with control rod No. 19.
The control rod failed to fall completely into the core when scram =ed fro = the fully withdrawn position; it dropped from 90 inches to approximately 23 inches.
With the aid of the pull'down coil, the control rod was driven in from 23 to 15 inches; the scram breakers were opened and No. 19 successfully fell into the core. Subsequently, the control rod was withdrawn to 90 inches and successfully dropped into the core with a measured drop time of 2.51 seconds.
During this surveillance, control rod No. 18 (the control rod that previously experienced difficulty) dropped into the core with a measured drop time of 2.35 seconds which is below the 2.4 second limit. The plant was returned to service following a safety review by the plant and Westboro Management; this review consisted of the following:
1.
The plant is presently operating in a mode to provide pro-tection for the plant during any accident condition resulting from the failure of'two maximum worth control rods to scram.
During the surveillance program the plant hasn't experienced difficulty with two rods either scramming or dropping in less than 2.5 seconds simultaneously.
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The difficulties that have been experienced involved two-
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group D control rods; surveillance testing and previous history
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indicate that these problems do not exist with c,ther control N
rods. Protection has been afforded for failure to scram for g
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tw maximum w rth r ds, a t t1 f 3. % dK/K.
The worth of M,',1019M eu t the' entire group D (8 rods) is approximately 4.0% AK/K. There-
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fore, the afforded protection is very conservative.
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Control rod No.'18 during the surveillance testing has been
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dropped successfully 14 of the last 14 times and during each
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United States Atomic Energy Commission August 7, 1972 7 Attentton: Directorate of Licensing Page 2.
test the drop time has shown improvement. The measured drop time is now below the 2.40 second limit.
On July 31, 1972 the Directorate of Licensing and Region I of the Directorate of Regulatory Operations was informed of the aforementioned occurrence and actions.
As a result of the above discussions and a complete review of the entire situation, Yankee offers the following:
1.
A tabulation of control rod drop times for all control reds measured during the Core X startup and surveillance program.
2.
A scheduled outage shall commence no later than October 31, 1972 for the installation of replacement control rods.
3.
Until control rods are replaced Yankee shall:
a.
Increase the frequency of the control rod surveillance program f rom every fourth weekend to every third weekend, b.
Supply the Commission with the results of all sur-veillance drop time results.
We trust you will find the above information and program satisfactory; however, should you desire additional information feel free to contact us.
Very truly yours, YANKEE ATOMIC ELECTRIC COMPANY h
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Donald E. Vandenburgh Vice President GCA/a=w Enclosure COMMONWEALTH OF MASSACHUSETTS)
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COUNTY OF WORCESTER
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Then personally appeared before me, Donald E. Vandenburgh, who, being duly sworn did state that he is a Vice President of Yankee Atomic Electric Company, that he is duly authorized to execute and file the foregoing request in the name and on the behalf of Yankee Atomic Electric Company, and that the statements therein are true to the best of his knowledge and belief.
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Armar.1 R. Soucy Notary Public My Co mission Expires September 9, 1977
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CORE X Regulataq-yh z,.,~
.x CONTROL ROD DROP DATA
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N N
N N
N Start of Life C:
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R No.
I II III M
M 3
3 2
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1 1.80 1.79 1.77 1.72 1.82 1.80 1.85 1.82 1.83 ilt l
2 1.54 1.58 1.56 1.54 1.61 1.58 1.62 1.60 1.60 3
1.49 1.47 1.48 1.44 1.51 1.52 1.57 1.54 1,55
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4 1.59 1.58 1.55 1.54 1.60 1.59 1.65 1.61 1.62 1
5 1.62 1.63 1.59 1.64 1.62 1.62 1.65 1.62 1.61 6
1.62 1.64 1.62 1.62 1.64 1.62 1.63 1.62 1.62 7
1.66 1.65 1.64 1.64 1.65 1.64 1.67.
1.64 1.65 il 8
1.94 1.97 1.84 1.94 1.95 1.91
-1.96 1.89 1.86-9 1.77 1.81 1.78 1.79 1.81 1.86 1.88 1.89 1.98 10 1.62 1.64 1.65 1.64 1.68 1.66 1.66 1.62-1.66 11 1.62 1.73 1.74 1.71 1.74 1,71 1.76 1.72 1.69 12 1.64 1.65 1.63 1.69 1.68 1.64 1.68 1.67 1.62 13 1.99 1,91 1.97 1.88 1.90 1.90 1.90
'1.87 1.90 14 1.84.
1.80 1.81 1.77 1.78 1.76 1.79 1.78 -
1.77 15 1.94 2.00 2.02 1.87 1.92 1.90 1.96-1.89 1.93 16 1.94 1.94 1.94 1.90 1.92 1.91 1.92 1.95 1.95 17 1.66 1.68 1.63 1.63 1.68 1.65 1.65 1.67
'1.62 1.66 18 2.62 3.01 2.56 2.65 2.72-2.47 2.35 19 1.90 1.81 1.78 1.84 1.89 1.96 2.23 2.25 2.02 2.51 20 1.84 1.80 1.75 1.75 1.79 1.73 1.76 1.76 1.761 1.78 21 1.66 1.68 1.65 1.64 1.65 1.58 1.68 1.66 1.55
-1.61 22 2.09 2,07 2.03 2.04 2.06 2.04 2.05 2.04 1.97 2.02-23 1.99 1.90 1.84 1.79 1.82 1.71 1.77 1.78 1.74 1.76 24 2.30 2.18 2.22 2.10 2.12 1.98 2.01 2.15 2.11 2.14 AVG 1,79 1.78
.1.76 1.74 1.77 1.75 1.80 h
1.76 1.79 of 23 2nd drop of Group D Additional Drop Times
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2.45 2.81 2.45 2.98 2.39 e-y o-
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AEC DISP auTI0li FOR PART 50 DOCKET MATERh_,
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COHTROL NO: 4398 FILE FROM: Yankee Atomic Elec. Co.
DATE OF DOC:
DATE REC'D LTR MEMO RFf CffHER Westboro, Mass.
01581 Donald E. Vandenburgh 8-7-72 8-10-72 X
To:
- f DRL 3 signed 37 SENT LOCAL PDR hPROPINFO CLASS:
INPUT NO CYS REC'D-DOCKET NO:
40 50-29 DESCRI?fl0N:
Ltr notarized 8-7-72 rpt pro-ENCLOSURES:
ble= on 7-29-72 when Control Rod #19 failed to fall completely into the core when scrammc d fa the fully withdrawn position; it dropped fm 90 inches to approximately 23 inches w/attchrit entitled Core X Control Rod Drop Data.....
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