ML19290B857

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Responds to IE Bulletin 79-24, Frozen Lines. Applicant Has Reviewed Freeze Protection Design Criteria & Considers Them Adequate
ML19290B857
Person / Time
Site: Millstone Dominion icon.png
Issue date: 10/29/1979
From: Counsil W
NORTHEAST NUCLEAR ENERGY CO.
To: Grier B
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
IEB-79-24, NUDOCS 7912140257
Download: ML19290B857 (2)


Text

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October 29, 1979 United States Nuclear Regulatory Commission Office of Inspection and Enforcement Region I 631 Park Avenue King of Prussia, Pennsylvania 19406 ATTN: Mr. B. H. Grier, Director Docket No. 50-423 AEC-MP3-194 Gentlemen:

SUBJECT:

Millstone Unit No. 3 I.E. Bulletin No. 79-24

Reference:

(1) B. H. Grier letter to W. G. Counsil dated September 27, 1979.

Reference (1) transmitted the subject I.E. Bulletin to Northeast Nuclear Energy Company requesting appropriate action. The subject Bulletin requested the Applicant to review safety-related process, instrument, and sampling lines to ensure that freezing does not occur during extremely cold weather. At the present time, the cold weather freeze protection equipment has not been designed or purchased for these systems. The Applicant has reviewed the design criteria to be used for freeze protection and considers them adequate. The criteria are as follows:

1. Exposed piping is heat traced to offset dissipated heat loss based on environmental conditions of 00F with 30 mph winds.
2. Exposed piping that is run vertically to below the design frost line (3 ft. below grade) is heat traced to 4 ft. and insulated to 5 ft.

below grade.

3. All small bore sample and instrument lines located in yard tunnels are heat traced and insulated. This tracing is continued for a span of 4 f t, upon entry into the heated structure.
4. Instrument air lines to safety-related air operated valves which are located outdoors or in pipe tunnels are heat traced and insulated.

Additionally, instrument air is supplied at a dew point of -400F,

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5. Individual circuits and their temperature sensors will be located to avoid localized cold spots subject to freezing.

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6.

Two-inch and smaller lines which are field run and will fall under the scrutiny of the Site Engineering Office will be installed in

.accordance with the requirements of the heat tracing and/or insulation specifications.

Because of the nature of the heat tracing, the ultimate assurance of reliable system

  • operation rests in the operational test of the system. System acceptance procedures will be sufficiently detailed to verify that all sections of the heat traced circuit are adequately monitored and maintain a uniform temperature.

Very truly yours, NORTHEAST NUCLEAR ENERGY COMPANY

-l >

William G. Counsil '

Vice President Nuclear Engineering & Operations BLC/WGC/cle . . ,

cc: luclear Regulatory Cornission . .

Office of Inspection and Enforcement Division of Reactor Washington, D. C. Operations . Inspect; ion . ...... . . . . . ...,

205.55. . . . . . . . .. . . . . .. .. .

bec:

J. M. Black (2); W. F. Bradley .(S&W); F. Sestak, Jr. (S&W); S. R. Toth; R. T. Laudenat; S. M. Oates..... .. . . .

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