ML20054G584

Submits Addl Info Re Auxiliary Feedwater Header Mod,Per NRC Request.Existing Headers Have Become Distorted Since Original Fabrication.Headers Will Be Replaced & Stabilized to Prevent Further Unacceptable Damage to Steam Generators

ML20054G584
Person / Time
Site:	Rancho Seco
Issue date:	05/20/1982
From:	Rodrigues R SACRAMENTO MUNICIPAL UTILITY DISTRICT
To:	Eisenhut D, Eisenhut D Office of Nuclear Reactor Regulation
References
TAC-48349, TAC-48384, NUDOCS 8206220086
Download: ML20054G584 (4)

Text

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E SMUD SACRAMENTO MUNICIPAL UTILITY DISTRICT O 6201 S Street Box 15830, Sacramento, Califomia 95813; (916) 452-3211 May 20, 1982 ATTN: Mark Padovan DIRECTOR OF NUCLEAR REACTOR REGULATION ATTN: DARRELL G EISENHUT, DIRECTOR DIVISION OF LICENSING U S NUCLEAR REGULATORY COMMISSION WASHINGTON DC 20555 DOCKET NO. 50-312 LICENSE NO. DPR-54 AUXILIARY FEEDWATER HEADER MODIFICATION (SUPPLEMENT)

This letter supplements the response of our previous letter pertaining to details of the Auxiliary Feedwater Header Modification.

Mr. M. Padovan re-quested R. Colombo to furnish an " overview" concerning the above mentioned modifications today.

This letter should provide that request.

The existing internal Auxiliary Feedwater Headers have become distorted since original fabrication. They must be replaced in order to provide the capability to inject Auxiliary Feedwater into the Steam Generators. They must also be stabilized to ensure that they remain in place and cause no further unacceptable damage to the internals of the Steam Generators.

The internal Auxiliary Feedwater Header will continue to serve as an extension of the Upper Cylindrical Baffle (Steam Shroud) to prevent high velocity steam crossflow near the mid-span of an unsupported length of steam generator tube.

The replacement design incorporates an external Auxiliary Feedwater Header, and six new penetrations through the Steam Generator Shell and through the Upper Cylindrical Baffle (Steam Shroud).

Stabilization of the internal Auxiliary Feedwater Header requires access at several points around the header.

In order to ensure that loose parts are eliminated or captured, access is required to eight equally spaced header support / fixation locations around the Steam Generator. Two of these locations are accessible from the Steam Generator secondary side manway.

In full consideration of all of the above, it is prudent to add six penetra-tions to the Steam Generators in order to:

ON

1) provide Auxiliary Feedwater injection,

2) provide access for internal header stabilization,

3) provide access for header support bracket and pin stabilization or removal.

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8206220086 820520 PDR ADOCK 05000312 P

PDR AN ELECIRlt SYSTEM SERVING MORE THAN 600 000

'N THI HfAPi 0F cal!FOFNeA These six new penetrations in each Steam Generator will be machined through the Steam Generator Shell and through the Upper Cylindrical Baffle (Steam Shroud). They will be machined to accept a suitable gasket and a flanged closure. A ring of threaded holes will be drilled and tapped into the Steam Generator Shell to provide closure at each penetration.

If you have any questions concerning this reply, please contact Ron Colombo at Rancho Seco.

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R. J. Rodriguez Manager of Nuclear Operations