ML20086E176
| ML20086E176 | |
| Person / Time | |
|---|---|
| Site: | Fort Saint Vrain  |
| Issue date: | 02/25/1974 |
| From: | Swart F PUBLIC SERVICE CO. OF COLORADO |
| To: | Oleary J US ATOMIC ENERGY COMMISSION (AEC) |
| Shared Package | |
| ML20086E172 | List: |
| References | |
| NUDOCS 8312060233 | |
| Download: ML20086E176 (7) | |
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1 INFORMATION REPORT No. 2 Facility: Fort St. Vrain Nuclear Generating Station Subj ect: Control Rod Drive Serial No. 30 - Failure of Orifice Valve to properly engage metal clad top reflector elements Report Date: February 25, 1974
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Scope This report is submitted to describe the failure of the orifice valve assembly of Control Rod Drive Serial No. 30, to properly engage and seat in the metal clad top reflector elements.
2.
Description At approximately 11:00 AM on Monday, February 25,1974, ett'ry of the Prestressed Concrete Reactor Vessel (PCRV) was made to facilitate manual insertion of the control rod of region 32.
The work presently being accomplished is an internal inspection of the Control Rod Drive (CRD) manual retract gear.
(See Information Report No.1, dated February 12, 1974).
At this time it was noted that the orifice assembly of CRD Serial No. 30 in Penetration No. 11 had not properly engaged the top metal clad reflector elements. This assembly had been inserted in the penetration on February 20, 1974.
Closer examination disclosed'the orifice assembly to be resting on the reserve shutdown material guide tube on top of the center reflector element.
The orifice assembly appeared to be offset approximately 3/8" - 1/2" to one side with the bottom of the reserve shutdown guide tube resting on the edge of the z
top of the reserve shutdown channel in the reflector. The centering guide pin had properly engaged the handling hole but the tapered guide fingers located at the bottom of the orifice valve had not yet 1
engaged the edge of the reflector to guide it into the proper position to assure engagement of both control rod and reserve shutdown guide f
tubes. The valve rested in such a position so as to forn an annular opening approximately one inch high between the bottom of the. orifice assembly and the top of the reflector.
3.
Cause Determination and Resultant Damage There was no damage.
The cause of the misalignment has not yet been determined.
It should be noted that this CRD had been previously installed with no problem.
All other CRD orifice valve assembly engagement was inspected and no problems found.
8312060233 740410 PDR ADOCK 05000267 S
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Information Report No. 2 Page 2 4.
Analysis of Misalignment The supplier of the CRD's (General Atomic (GA)) was notified.
and an inmediate inspection of the situation made.
Analysis are presently being made to determine the cause of the misalignment to facilitate renedial action.
Because the CRD orifice valve assembly-is designed to rest on top of the core and is not supported by the CRD, the CRD was not prevented from being properly inserted into the penetration in the PCRV top head.
The control rods had been inserted and functionally tested for operability successfully. The orifice valve misalignment did not, in any way, prevent the control rods from being inserted properly and to_the proper elevation in the core.- At no time was the operation of the control rods hampered.
The operability of the reserve shutdown system was not impaired either. Even with the bottom of the guide tube resting on top of the reflector, the passage way through the guide tube was in no way restricted
,to prevent proper inse,rtion of the reserve shut.down material.
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Mr. John O' Leary, Director Directorate of Licensing DSilC Washington, D. C.
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SUBJECT:
Information Report No. 2 Control Rod Drive Serial No. 30 - Failure of Orifice Valve to Properly Engage Metal Clad Top Reflector Elements
Dear Mr. O' Leary:
The attached report is subritted as an furormational report to apprise the AEC of the status of Fort St. Vrai c..
The report should be considered preliminary and will be followed by suosequent reports stating progress of our engineering investigation.
Very truly yours,
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.Frederic E. Swart Superintendent Fort St. Vrain Nuclear Generating Station ec: Director, Region IV, Denver
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