ML20100G088
| ML20100G088 | |
| Person / Time | |
|---|---|
| Site: | Indian Point  |
| Issue date: | 11/30/1984 |
| From: | Otoole J CONSOLIDATED EDISON CO. OF NEW YORK, INC. |
| To: | Murley T NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| IEB-84-03, IEB-84-3, NUDOCS 8412070145 | |
| Download: ML20100G088 (6) | |
Text
7.
^C' John D. dToole vce Prescent
, i Conschdated Edison Company of Ne.v Ycrk, Inc.
A trying Place, New York NY 10003 Telephone (212) 460-2533 November 30, 1984 Ret Indian Point Unit No. 2 Dockent No. 50-247 Dr. Thomas E. Murley, Regional-Administrator Region I U.S. Nuclear Regulatory Comaission 631 Park Avenue King of Prussia, Pa. 19406
Dear Dr. Murley:
Attachment A to this letter contains our response to IE Eulletin No.
84-03 " Refueling Cavity Water Seal."
This-response is being provided pursuant to Section 182a of the Atomic Energy Act as amended.
Should you or your staff'have any questions, please contact us.
Very ruly yours,
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No. 310'E22t3 Qua!!!ied in New You County Comm!s !on E:: pins 1,:n:n 30,1C35 If 8412070145 841130 PDR ADOCK 05000247
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Document Control' Desk Washington, D.C. 20555 Senior Resident Inspector
' U.S. Nuclear Regulatory Commission P.O. Box 38 Buchanan, New York 10511 7
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sg ATTACHMENT A Response to I.E. Bulletin No. 84-03
-Refueling Cavity Water Seal-Consolidated Edison Company of New York, Inc.
Indian Point Unit No. 2 Docket No. 50-247 November 1984 4
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.m ATTACHMENT A Pesponse to NRC I.E. Bulletin No. 84-03 Action To Be Taken'By' Plants' Prior Tb Beginning Refueling Or Within 90 Days Of Receipt Of This Bulletin, whichaver Is Sooner:
2.
Evaluate the potential for and consequences of a refueling cavity water seal. failure and provide a summary report of these actions.
Responses-Pricr'to flooding the refueling cavity in preparation for refueling at Indian Point 2, it is necessary to install closure seals over existing openings in the refueling cavity: floor. One such seal is a ring seal to close off the ventilation annulus surrounding the reactor vessel. Indian Point 2 employs an elastomeric inflatable ring manuf'ctured by Presray Inc. for this application. This design was first itsstalled in 1976 and
.is Seismic,I.
To insure that the Presray seal would proper 1v seat in the annular opening the _ annulus surface and edges were resurfaced,. machined and cleaned to suit. Installation of the Presray seal consists of placing it
.in the annulus and pressing it into place. Before inflation, a heavy, flat metal annular plate is positioned on the flat top surface of the
-Presray seal.to weight it and maintain seal stability upon inflation and subsequent cavity flooding.
At Indian Point 2, the annulus in which the Presray seal is placed in 2 1/4" in width and bounded by the reactor vessel flange and the lip of the 4'
biological shield concrete wall as shown in~ figure'l.
Both'of'these structures are rigid and provide ample support for maintaining a tight seal.
In contrast,' the Haddam Neck annulus is of greater width, and must Lutilize two. concentric Presray seals with a floating seal ring between.
'The mechanics and dynamics of the two annulus seall'q designs are different.
For the Indian Point 2 Presray seal, two inflation hoses' supplied from
. independent sources are attached to the seal 1800 apart. Each inflation system is equipped with a, deflation restricting orifice to maintain a minimum seal inflation pressure assuming a hypothetical severance of one hose.
Continuous inflation of the seal is achieved by supplying N2 at 30 psig. Although the design life of the seal is 5 years, a new seal' and accessory equipment are normally used at each Indian Point 2 refueling. The system also incorporates a pressure relief
_ valve to prevent overpressurization of the seal.
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The Presray seal configuration of Indian Point 2 presents a static and
. dynamic seal insuring positive protection against gross cavity water leakage as experienced at Haddam Neck. During the past six refuelings, even minor. leakage has not occurred at these seal interfaces. Due to the configuration of the seal cross-section and the fit of the seal in the annulus, even the loss of seal inflation-pressure will not cause the seal to dislodge from its sealing mode although some leakage may be present.
When the Presray seal is. in service, under a minimum height of 25 feet of water (approximately 11 psig), any gas. leakage.frem the top would be readily observable as rising bubbles from the refueling deck.
A gas leak below the sealing junction would result in gas consumption as evidenced by a decreasing pressure on,the gas supply pressure gauge.
During prior seal installation a gas leak has never been observed nor has a change in the gas supply pressure occurred.
Based on the design provisions described above it is concluded that the Indian Point 2 Presray seal installation will not result in a gross leak.: In the improbable event that an undersirable decrese in reactor cavity water level should occur a procedure is available to the
-operators. The procedure covers evacuation of personnel from Containment, placement of fuel in transit, closure of Puel Transfer Tube valve and Spent Puel Pit Gate and establishment of an RHR pump path from othe containment sump if a fuel assembly is in the refueling cavity. An alternate supply of water would be the Recirculation pump in the Recirculating sump.
Even if the water level were to drain down to the vessel flange elevation, the spent fuel assemblies stored in the spent fuel pool would not be uncovered.
Any additional drain down required to expose the spent fuel assembles stored in the spent fuel pool is precluded by the geometric configuration and relative elevations. The spent fuel. pool under this unlikely condition would have a minimum water level of 15 feet which ensures that the spent fuel assemblies remain covered.
-In conclusion, based on the above information, no additional actions are necessary.
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