ML20084Q401

Submits Findings of Insps of Ohio Injector Co Valves Installed at Facility.Insp Revealed That There Are Two Different Types of Valves.Two of Five Valves Have Higher Bonnets.High Bonnet Valves 1-1001-185A & B Repaired

ML20084Q401
Person / Time
Site:	Quad Cities
Issue date:	12/28/1973
From:	Stephenson B COMMONWEALTH EDISON CO.
To:	Oleary J US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20084Q404	List: ML20084Q401 ML20084Q408
References
BBS-73-282, NUDOCS 8306130253
Download: ML20084Q401 (2)

Text

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U. S. ATOMIC ENERGY COMMISSION .

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REFERENCE:

A. Quad-Cities Nuclear Power Station, Unit I and 2 Dockets 50-254 and 50-265 License DPR-29 and DPR-30 B. My letter to you 8B5-73-266 of December 4, 1973.

Dear Mr. O' Leary:

I The purpose of this letter is to report the findings of our further in-spections of the Ohio injector Company (0IC) valves Installed at Quad-Cities Nuclear Power Station. These inspections were conducted after the disc sep-arated frem the stem of one of the OIC valves as reported in my letter to you on December 4, 1973.

INVESTIGATION After discovering that the stem to the downstream service water Isolation valve 2-1001-185B to the 2B RHR system heat exchanger was uncoupled from its disc, an inspection of valves installed in similar locations revealed that i five valves of this type are installed in the station; two in Unit I and three in Unit 2. All valves were checked for sten-disc attachment by attempting to rotate the stem with each valve in an intermediate position. Since these are gate valves rotation of the stem should not be possible; no abnormalities were detected. In addition to the 2-1001-1858 valve, two valves were dis-assembled and inspected.

The results of the inspection revealed that there are two different types of valves. Two of the valves have higher bonnets than the other three valves.

These two valves are 2-1001-185B and 1-1001-183A. The inree valves with lower bonnets are numbered 1-1001-1878, 2-1001-1865 and 2-1001-1878 Measurements taken on a high bonnet valve and on a low bonnet valve show  ;

that the stem-disc assembly on a low bonnet valve is Ilmited in travel to its

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l backseat by 3 3/8 inches less than the stem-disc assembly on the high bonnet l valve. The significance of this is that in the high bonnet type valve the disc is pulled out f ar enough so that it comes off the valve body ways and falls off its stem. Conversely, the low bonnet type valve is limited in l trevel so that when it is on its backseat the disc is still sitting in the valve body ways and cannot fall off its stem.

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Mr. John F. O' Leary December 28, 1973 The 1-1001-185A high bonnet valve was repaired in the same manner as the 2-1001-185B valve. This repair consisted of drilling a 1/4 inch hole per-pendicular to the disc on either side of the disc notch and bolting a 1/4 inch thick strap on either side of the disc over the flared stem. Nuts were tightened and welded to the bolts.

EVALUATION No repair was necessary on the low bonnet valves 1-1001-1878, 2-1001-1868 and 2-1001-1873 since they are correctly designed and the stem-disc arrange-ment cannot uncouple when the valves are on their backseats. The repair to both high bonnet valves 1-1001-185A and 2-1001-1858 pinned the disc onto the stem and the coupling cannot disengage. Therefore, we now have assurance that all of the OIC valves installed at Quad-Cities will perform their in-tended functions in the future.

Since the valves in question were purchased and installed during plant construction by the General Electric Company, we have advised them of the results of our investigations. We have requested that they review this apparent design inadequacy further and make recommendations for any further corrective action with regard to this problem.

Very truly yours, COMMONWEALTH EDISON COMPANY QUAD-CITIES NUCLEAR POWER STATION c)h hl .

M @ B. B. Stephenson ~

Station Superintendent BBS/dkp BBS-73-282 cc: Regional Director Directorate of Regulatory Operations - Region 111