ML19309C217

Outlines Plans for Cycle 4 Reload Outage Steam Generator Insp Per Amend 52 to License DPR-65.Resolution of Cycle 3 Startup Commitments Encl

ML19309C217
Person / Time
Site:	Millstone
Issue date:	03/31/1980
From:	Counsil W NORTHEAST UTILITIES
To:	Reid R Office of Nuclear Reactor Regulation
References
TAC-11348, TAC-11561, TAC-12505, TAC-42846, NUDOCS 8004080309
Download: ML19309C217 (6)

Text

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L J l P' Z " "l.'*J,Z T.7l March 31, 1980 Docket No. 50-336 Director of Nuclear Reactor Regulation Attn:

Mr. R. Reid, Chief Operating Reactors Branch #4 U. S. Nuclear Regulatory Commission Washington, D. C.

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Reference:

(1)

R. Reid letter to W. G. Counsil dated May 12, 1979 Gentlemen:

Millstone Nuclear Power Station, Unit No. 2 Resolution of Cycle 3 Startup Commitments In Reference (1), the NRC Staff issued License Amendment No. 52 and the supporting Safety Evaluation to Facility Operating License No. DPR-65, for Millstone Unit No. 2.

Documented in Reference (1) was a commitment for Northeast Nuclear Energy Company (NNECO) to provide the plans for the Cycle h reload outage steam generator inspection.

In response to that commitment, NNECO hereby provides the following information.

The steam generators in use at Millstone Unit No. 2 will be inspected during the upcoming refueling outage in accordance with the Reference (1) commitment. The purpose of this inspection will be to detect and assess tube denting and/or defects. NNECO emphasizes that this is a supplementary inspection and is in addition to the inspections required by Plant Technical Specifications, wherein a 3% sample population of steam generator tubes will be inspected for defects.

Multi-frequency eddy current techniques will be utilized to assess tube denting and measure defects. These techniques represent an advanced level of non-destructive testing (NDT) technology and will yield results of maximum quality and quantity.

NNECO also intends to perform a profilometer inspection of the steam generator tubes in an attempt to better define denting effects. An eight- (8) point probe which is capable of determining radial dimensions based on the deflections of eight (8) cantilevered " fingers" will be used to determine tube strain.

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Since profilometer inspection techniques have not been developed to the point l

where a field-hardened system is available, NNECO will be performing these inspections on an experimental basis and will provide the results of these 1

I examinations to the Staff for informational purposes only.

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The following information pertaining to the supplementary steam generator testing program is provided in the attached table.

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I e' Sample size / location e Limiting results i

e Action requirements l

l NNECO has determined that the inspections discussed above in conjunction with r

i the inspections required by Technical Specifications significantly reduce the

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probability and consequences of steam generator tube failure at Millstone Unit No. 2 during Cycle 14 operation. Steam Generator degradation is further reduced by the operation of the Full Flow Condensate Polishing System.

To date during Cycle 3, steam generator performance at Millstone Unit No. 2 has been adequate.

l We trust you find this information responsive to the Reference (1) commitment.

I Very truly yours,

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i NORTIIEAST NUCLEAR ENERGY COMPANY f'll W. G. Counsil l

Vice Presideit a

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DOCKET N0. 50-336 l

ATTACliMENT MILLSTONE NUCLEAR POWER STATION, UNIT NO. 2 RESOLUTION OF CYCLE 3 STARTUP COMMITMENTS MARCH, 1980 l

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OUTLINE OF SUPPLEMENTARY EDDY CURRENT TESTING PROGRAM FOR STEAM GENERATOR TUBE DENTING ASSESSMENT A.

STEAM GENERATOR SAMPLE SELECTION Either steam generator shati be inspected, subject to the requirements defined in Table 1...

B.

STEAM GENERATOR TUBE SAMPLE SELECTION AND TESTING Minimum sample size, sample

• Location, test result classifica-tion, and action requirements shati be as specified in Table 1.

Percentages in this table refer to unplugged tubes.

These samples shaLL include regions where denting ef fects were greatest in pre-vious inspections.

C.

DEFINITIONS Tube Support Plate Tubess Tubes that pass through a partial tube support plate.

Accessible Tube A tube that is accessible to remote," finger walker"-type of devices used for conducting eddy current examinations.

Egg Crate Tubess Tubes that pass through " egg-crate" supports but do not pass through tube support plates.

Blockage:

Tube condition that prevents passage of a probe of the nominal diameter indicated.

Denting:

Constriction of the inconet tubing that occurs at tube / tube support junctions as a result of magnetite buildup in these regions.

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TABLE 1 - NOTES D.

TUBE TESTING, TUBE SUPPORT PLATE TUBES Inspection of the steam generator tube from the point of entry hot leg side, through the Lower tube support plate on the cold leg side, per requirements of Tabte 1.

P E.

TUBE TESTING, EGG CRATE TUBE Inspection of the steam generator tube from the point of entry, hot Leg side through the uppermost egg ' crate, hot leg side.

F.

TUBE TESTING, PERIPHERAL TUBE Inspection of the steam generator tube from the point of entty, hot leg side through first egg crate, hot leg side.

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