ML19290B841

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Responds to IE Bulletin 79-24, Frozen Lines. Details Freeze Protection Measures
ML19290B841
Person / Time
Site: Seabrook  NextEra Energy icon.png
Issue date: 10/25/1979
From: Devincentis J
PUBLIC SERVICE CO. OF NEW HAMPSHIRE
To:
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
IEB-79-24, NUDOCS 7912140231
Download: ML19290B841 (2)


Text

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UlPUBLIC Companyof NewSERVICE Hampshire SEACROOK STATION Engineering Office:

20 Turnpike Road Westborough, MA 01581

, October 25, 1979 SBN-103 T.F. B 4.2.5 U.S. Nuclear Regulatory Ccmmission Regicn I 631 Park Avente King of Prussia, Pennsylvania 19406 Attention: Office of Inspection and Enforcement

Reference:

1. Docket No. 50-443 and 50-444
2. NRC letter dated September 27, 1979
3. IE Bulletin No. 79-24 F2 ject: Frozen Lines

Dear Sir:

We have the following responses to the above referenced IE Bulletin:

Seabrook units 1 and 2 freeze protection design for safety-related process, instrument and sampling lines is based on the following:

1. Lines to be heat traced will be identified on P&I, flow or loop diagrams.
2. Safety-related process, instrument and sampling lines will be redundantly heat traced in outdoor runs or in unheated indoor areas where the ambient temperature may fall below freezing.
3. Thermostats will be located in unprotected areas so that thermostats will sense the lowest ambient temperature.
4. Thermostats will also be installed to measure pipe temperatures.
5. Thermostats will be adjusted to turn on the heat tracing protection when the ambient temperature falls below 40 0F,
6. An alarm will be displayed on plant computer upon failure of the heat tracing system to maintain pipe temperature above 350F. (Power failure, cable failure).

1574 025 mmo s3)

U.S. Nuclear Regulatory Commission Page 2 SBN-103

7. Operator will turn off faulty system and turn on the redundant stand-by system. This is a manual operation. Both systems should not operate at the same time.
8. Sufficient heat tracing and insulation will be installed gn each pipe to prevent freezing when ambient temperatures fall to -18 F.

We trust this information will be satisfactory.

Very truly yours,

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[ John DeVincentis Project Manager HEW:tla 1574 026