ML19326B505
| ML19326B505 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 04/05/1974 |
| From: | Phillips J ARKANSAS POWER & LIGHT CO. |
| To: | Knuth D US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| NUDOCS 8004150841 | |
| Download: ML19326B505 (3) | |
Text
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i H ELPIN G BUILO ARKANSAS ARK ANS AS POWER & LIGHT COMPANY STH & LouiGIANA GT AEeTS
- L,TTLe AOCK. A AK ANSAS 72203 45013372-4311 April 5, 1974 Mr.
D. F. Knuth Director of Regulatory Operations Office of Regulation e
United States Atomic Energy Commission Washington, D. C.
20545
Subject:
Arkansas Power & Light Company Arkansas Nuclear One-Unit 1 Docket No. 50-313 Control Rod Drive Position Indicator Failure
[mV)
Dear Mr. Knuth:
On March 4, 1974, we reported a possible significant deficiency concerning the failure of at least fifteen (15) control rod drive (CRD) position indicators at Arkansas Nuclear One-Unit 1 to Mr. M. S. Kidd, Reactor Inspector, Region II.
The failure of the indicators was a result of binding of the relative position indicator (RPI) and sticking, in a closed position, of the absolute position indicators ( API) during hot functional testing.
1 Although the problems reported represent an operational restriction, no safety consequences can be projected for the RPI and API f ailures based on the ANO-1 safety analyses and operating procedures.
In the event of a CRD position indicator failure, a false signal will be generated indicating assymmetric stuck or dropped rod symptoms as stated in FSAR Section 7.2.2. 3.4 (4),
- p. 7-25.
A failure outside the nine inch band allowed by Technical Specification 4.7.1.2 for normal rod group opera-tion would indicate a false rod position either outside the group average or at the in or out limits.
If the rod cannot be located with the absolute or relative position indicator
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or the in or out limit lights or if it is located and found to be more than 9 inches from the group average, it is then declared inoperable as required by Specifications 4.7.1.3 and 4.7.1.2, respectively.
If a control rod is declared inoperable, Specification 3.5.2.2 places restrictions on the continued operation of the plant to insure that adequate shutdown margin is available.
Plant Operating Procedure 1203.03, Rev. 1, " Control Rod Drive Mal-function Action", provides instructions to the operators for actions to be taken in the event of assynmetric rod indica-tions.
In conclusion, the design of the CRD position indication system c
the Technical Specification requirements, and the CRD mal-function procedures combine to protect the plant and isolate faults in such a manner as to preclude the existence of an unsafe operating condition.
As corrective action, the benefits of both hardware and pro-cedural changes are being considered concurrently by Babcock and Wilcox with the overall goal being improved full power availability and ease of operation.
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Very truly yours, a
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J.
D. Phillips Senior Vice Presider t JDP : lt cc:
Mr. Norman C. Moseley, Director United States Atomic Energy Commission Directorate of Regulatory Operations Region II 230 Peachtree Street, N.W.,
Suite 818 Atlanta, Georgia 30303 b
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l STATE OF ARKANSAS
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SS COUNTY OF PULASKI
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J. D. Phillips, being duly sworn, states that he is a Senior Vice President of Arkansas Power & Light Ccxupany; that he is authorized on the part of said Company to sign and file j
with the Atomic Energy Commission this Supplementary Informa-tion; that he has read all of the statements contained in such Information, and that all such statements made and matters set forth therein are true and correct to the best of his know-ledge, information and belief.
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Phillips
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3 SUBSCRIBED AND SWORN TO before me, a Notary Public in
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and for the County and State above named this day of 47.i 1974.
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Notary Public My Commission Expires:
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