ML20090E177
| ML20090E177 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 05/03/1974 |
| From: | Perkins T NIAGARA MOHAWK POWER CORP. |
| To: | Skovholt D US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| 4231, AO-50-22--74-7, AO-50-220-74-7, NUDOCS 8303140065 | |
| Download: ML20090E177 (4) | |
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,s NI AGARA MOHAWK. POWER CORPORATION NIAGARA MOHAWK 300 EptlE BOULEVARD WEST SYR ACUSE, N. Y.1:s202 May 3, 1974 p
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6()-22O (g' WiY J3 197.;=t'.2 Mr. Donald J. Skovholt
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IE-Assistant Director for Reactor Operations A
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Division of Reactor Licensing
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(N.Gl((p.f-q Q" 4gs United States Atomic Energy Commission h'ashington, D.C.
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Dear Mr. Skovholt:
In accordance with Technical Specifications for Nine Mile Point Unit 1, the enclosed Abnormal Occurrence Report is submitted. This report is in accordance with the format set forth in Regulatory Guideline 1.16.
Very truly yours,
.4 R.R. Schneider.
Vice President - Electric Operations RRS/bar 4
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COPY SENT REGION u
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-.i ABNORMAL OCCURRENCE REPORT-1.
- Report-No.
74-7 2a.
Date April 30, 1974 2b.
Occurrence Date April 25, 1974 3.
Facility ~
Nine Mile Point Nuclear Station ' nit.1-U 4.
Identification of Occurrence Control Rc,d Blade Tube Inversion 5.
Conditions Prior to Occurrence Unit I was shutdown for annual refueling 6.
Description of Occurrence
-During the previous operating cycle on September 25, 1973-you' informed us of a possible problem involving inverted tubes in. control rod blades.
In our response to your letter and further coramunication we committed to:
1.
A shutdown margin test on each control rod (completed in November 1973 with negative results).
2.
An eddy current testing program on each control rodIduring the next refueling outage.
-3.
A change out of any affected control-rod.
On April 24-25, 1974'- the eddy current testing evaluation' of individual:
control rod blades in the Nine Mile-Point Unit.1 reactor-core was
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completed. The. eddy current test used was.that.as-described in the General Electric submittal to your office on October 8,fl973. -The results of the testing showed two ' control rodiblades with possible -
inverted tubes.
Immediate steps were taken to insure _that the'. cells effected would be in a less' reactive condition.than that.as' experience
!during the previous cycle..The control. rod would not.be~ withdrawn and.
only two bundles were present in the cell affected. The co_ntrol blades-will be changed in these two cells later..during. the core' refueling.
7.
Designation of' Apparent Cause of the' Occurrence.'
Manufacturing Deficiency-
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8.
Analysis of Occurrence.
.The inverted sheths were found at core locati'on. 22-15 and. 30-39 two.
widely dispensed-locations..In addition. shutdown margin' demonstrations-sw 1
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,~, Abnormal Occurrence fieport.
April 30, 1974 in November 1973 showed no inade'quacy in more than necessary~ shutdown.
margin.
Based on this it.is concluded that no hazard was presented to:
the general public.
'9.
Corrective-Action The two control blades will be changed.
In addition the Site Quality Control Organization will prevent further. manufacturing deficiency from being used. This organization was not in existence when the. original control blades were obtained.
10.
Failure Data First Failure' of this nature.
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ABNDRMN ENCE'ADR50h/74 h
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TUBEINVERSIONINTWOCdNTR0[ BLADES 2
PURSUANT TO TECHNICAL SPECIFICATIONS 1.13d WE' ARE REPORTING AS AN' ABNORMAL r
0CCURRENCE(A0R50-220/74-7) THE INVERSION OF TUBES'IN TWO CONTROL R0D. BLADES AT NINE MILE POINT NUCLEAR STATION UNIT 1.
0, DURING THE SPRING 1974 REFUELING OUTAGE AN EDDY CURRENT. TEST WAS MADE OF EACH. CONTROL BLADE IN THE REACTOR CORE. THE RESULTS WERE ANALYZED ON APRIL 24 AND INDICATED TUBE INVERSION IN. CONTROL ROD Bl.ADES, 30-39 AND 22-19.
THE EDDY. CURRENT TESTING VERIFIES THZ NON' INVERSION'0F INDIVIDUAL TUBES IN EACH WING OF THE CONTROL ROD BLADE. THEREFORE IT IS A' CONSERVATIVE TEST IN THAT THE RESULTS INDICATE NON-INVERSION GHLY AND NOT INVERSION. '
THE IPBIEDIATE CORRECTIVE ACTION PERFORMED, WAS NOT LOADING THE CONTROL CELL TO ITS FINAL. REACTIVE CONDITIONS DURING FUEL MOVEMENTS.. THIS WILL INSURE THAT THE CONTROL BLADE'" HOLDS DOWN" LESS REACTIVITY NOW THAN DURING ANY: POINT IN THE i PREVIOUS OPERATING CYCLE. DURING THE OPERATING CYCLE SHUTDOWN MARGIN TESTING WAS PERFORMEDONEACHCdNTROLR0DINTHEREACTOR. THIS VERIFIED THAT MORE THl.N ADEQUATE SHUTDOWN MARGIN EXISTED ON EVERY CONTROL BLADE IN.THE CORE.
THE FINAL CORRECTIVE ACTION WILL BE TO REPLACE THE TWO' CONTROL BLADES WITH BLADES VERIFIED TO'BE NON-INVERTED.
BASED UPON THE FACT THAT MORE THAN ADEQUATE SHUTDOWN MARGIN EXISTED DURING THE'0PERATING CYCLE AS DEMONSTRATED, N0 HAZARD WAS PRESENTED TO THE GENERAL PUBLIC OR THE STATION DURING THE PREVIOUS OPERATING CYCLES.
1HISr!S THE FIRST FAILURE OF THIS NATURE.
4 THONAS:J. PERKINS STATION SUPERINTENDENT NINE. MILE POINT NUCLEAR STATION h'
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