ML19345E300
| ML19345E300 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 05/23/1960 |
| From: | Coe R YANKEE ATOMIC ELECTRIC CO. |
| To: | |
| References | |
| NUDOCS 8101060726 | |
| Download: ML19345E300 (2) | |
Text
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YANKEE ATOMIC ELECTRIC COMPANY 441 STUART STREET, BOSTON 16. MASSACHUSETTS
'<ay 23,1960 U. S. Atomic Energy Commission
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Attention: Division of Licensing and Regulation f
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Dear Sirs:
AEND':4ENT NO. 23 TO LICENSE APPLICATION DATED JUNE 29, 1956 (Docket No. 50-29)
Pursuant to the Atomic Energy Act of 195h and the Commission's Rules and Regulations issued thereunder, Yankee Atomic Electric Company hereby supplements and amends its License Application dated June 29, 1956, so as to reflect the following modifications of design:
Part B - Technical Information Os Section 101.
Core Mechanical 1.
Provision for irradiating samples Design.
of reactor vessel material.
Four 3-inch diameter holes will be drilled in the upper flange of the lower core support barrel, and four vertical guide channels will be installed on the outer surfact of */ae thermal shield.
The purpose is to provide for future insertion of te capsulated specimens of reacter vessel material in the annuhr space he ; ween the thermal shield and the vessel vall to determine the long-term effects of fast neutron bombardment on the physical properties of suc!..naterials.
The lower core support barrel is described on Page 101:9 of the License Application, along with other components of the core structure.
The upper flange of the lower core support barrel rests on a machined ledge at the reactor vessel flange and carries the weight of the core and core structure.
The flange consists of a Type 30h stainless steel ring approximately 7'1" in internal diameter, 8'6n in outside diameter and 2}" thick, which is welded to the barrel itself. After addition of the four holes, stresses in the flange and barrel are within the ASE Code allowable stress for Type 30h stainless steel at operating temperature.
During operation, these holes will be covered by the flange of the upper core support barrel, so that there will be no change in hydraulic conditiona or main coolant flow distribution.
Four channel-shaped stainless steel guides on the outside surface of the thermal shield will be used to position samples of reactor vessel material that may be inserted at some futura time.
These guides will extend O,
from the top of the thermal shield ta t point just below the center.
They will be securely welded at the top and fastened at their lower end by a captive cap screw.
There will be no effect on the nuclear or thermal prop-erties of the thermal shield and insignificant effect on hydraulic flow.
U, Atemic Ene:c Lordusion Page 2
,, Division of Licansing and Regulation May 23,1960 9
It is important to rake tnece rodiGeations before reactor opera-tion begina, since the lower core support barrel and the thermal shield will become activated during operation.
Secticn 101.
Core Mechanical 2.
Modification of control rod drive Design shaf ts to equalize hydraulic pres-Section 213. Reactor Control aures on spring-loaded plunger in System coupling between drive shafts and control rods.
The control rod drive nechanism drive shafts are coupled to the control rodo by means of a four-fingered clutch, the hinged fihgers of which are held in the outward engaged position by a spring-loaded plunger.
This plunger normally has no hydraulic forces acting upon it, but during scram, due to the dounward travel of the drive shaft out of the mechanism pressure housing, there are unbalanced hydraulic forces acting which tend to move the plunger toward the unlatched position.
Unlatching during scram would result in free fall into the core of the control rod and follower, with the possi-bility of mechanical damage to the rod and core internals.
Accordingly, all 2h control red drive mechanisms will be modified by drilling twelve 1/h-inch diameter radial holes through the wall of each hollow drive shaft.
The six lower holes will be at a point that is always in the reactor vessel and the six upper holes at a point that is always within the pressure housing. As a result, an additional path vill be provided for the flow of water from the reactor vessel to the mechanism O
h using, thereby reducing the pressure differential that exists during scram to a value below that required to unlatch the coupling.
The addition of these holes will not reduce the strength of the drive shaft since the renaining cross-sectional area at the point where the holes are drilled is greater than the minimum area in the stressed portion of the drive shaft.
Respectfully submitted, YANKEE ATOMIC ELECTRIC COMPANY I )
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Roger J. Co,e VicejPresid'ent Commonwealth of Massachusetts Pay 23,1960 Suffolk, es.
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Then personally appet. red before me Roger J. Uce, who, being duly sworn, did state that he is r. Vice President of Yankee Atomic Electric Company, the applicant herein, that he is duly authorized to execute and file the foregoing amendment in the name and on behalf of Yankee Atomic Electric Cogany, and that the statements in said amendment are true to the best of his knowledge and belief.
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CONALD G. ALLEN. NOTARY PUDUC l
My C mmico Evan Jan. 21, 1957,
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