ML18136A195
| ML18136A195 | |
| Person / Time | |
|---|---|
| Site: | Surry, North Anna  |
| Issue date: | 11/01/1979 |
| From: | Stallings C VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| IEB-79-24, NUDOCS 7911200216 | |
| Download: ML18136A195 (4) | |
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VIRGINIA ELECTIUC A.ND POWER COMPANY RICHMOND,Vn;ro:rN.IA 23261 November 1, 1979 Mr. James P. O'Reilly, Director Office of Inspection and Enforcement U. S. Nuclear Regulatory Commission Region II 101 Marietta Street, Suite 3100 Atlanta, Georgia 30303
Dear Mr. O'Reilly:
I*, I ~.i
-4 Serial No.
807 PO/RMT:baw Docket Nos: 50-280 50-281 50-338 50-339 License Nos: DPR-32 DPR-37 NPF-4 CPPR-78
SUBJECT:
IE BULLETIN 79-24 This is in response to IE Bulletin No. 79-24, "Frozen Lines" for Surry Power Station Unit Nos. 1 and 2 as well as North Anna Power Station Unit Nos. 1 and 2.
Very truly yours,
- ,,
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<-i./,,) vf/t"iC[cnry7 C. M. Stallings Vice President-Power Supply and Production Operations Attachment cc:
Director, Division of Operating Reactors Office of Inspection and Enforcement Washington, D. C.
20555 7 9111.00 2-16
NORTH ANNA POWER STATION RESPONSE TO IE BULLETIN 79-24 FROZEN LINES Attachment page 1 The Staff has already reviewed this concern in FSAR Supplement S9-67.
That information is provided here for your review.
COMMENT 9.67 For those components not housed with temperature control areas, identify and discuss the protective measures to be taken to assure their operation with regard to potential failures or malfunctions occurring due to freezing, icing or other adverse environmental conditions, which are essential in attaining or maintaining a safe shutdown.
RESPONSE
Components referred to are shown on Figure 1.2-2 of FSAR.
- 1.
Main Circulating Water Intake Structure -
The auxiliary service water pur:ips and the screen wash pumps are within an enclosed are;J.,
and therefore protected from the weather.*
The piping to and from these punps and the punp bodies are redundantly heat traced.
The motors are equipped with heaters.
- 2.
Refueling water storage tanks - The refueling water storage tanks and chemical addition tanks are recirculated as required to pre-vent freezing.
These tanks are insulated and of such size and volume that freezing is not a problem.
All exposed piping to and from these tanks is redundantly heat traced.
- 3.
110,000 gal condensate tanks -
The 110,000 g~l condensate tanks are not heated.
These tanks are within thick concrete enclosures and the contents may be recirculated if required to prevent freezing.
All exposed piping to and from these tanks is redun-dantly heat traced.
- 2.
Main Steam House - The main steam valve house is enclosed but unheated.
During plant operations, sufficient heat is provided by the heat loss from piping.
If required during periods of plant shutdown, provisions are made for portable electric heaters.
- 5.
Fuel Oil Pump Room - The fuel oil pump room is enclosed but unheated.
Because of the type of fuel oil used, heating is not required.
6 *.
Underground pipe chases - Station underground pipe chases containing piping necessary for attaining and maintaining a safe shutdown are located below ground to a sufficient depth to be below the frost line.
Therefore, no heating is required to prevent freezing.
- Attachment page 2 The following additional information, not included in the refer£>nced FSAR Supplement, is also provided.
A design change was implemented after the Unit 1 Operating License was issued and during Unit 2 construction, to install a Casing Cooling System (a subsystem of the> Recirculation Spray System) for each Unit.
This modifi-cation added a Casing Cooling Tank and Pumphouse as sho'.>TD on FSAR Figure 1. ?.-2.
The pumphouse for each Unit has electrical heaters for space heating.
This provides for freezing protection.
The tank is insulated and is recirculated as required to prevent freezing.
On Unit 2, the level transmitters for the tank are protected by heated enclosures.
On Unit 1, a design change is being prepared to provide heated enclosures.
Should this design change not be ready in the event of a severe winter, temporary measures will be taken to prevent free.zing of the level transmitters.
It should also be noted that each main pipe run is provided with its own priraary ani redundant heat trace circuit.
The branch lines from the main runs of pipe are individually heat traced with their own primary and redundant circuits.
In addition, each circuit is provided with its own low temperature alarm provicing an indication of local circuit performance.
pr.Lor tures All heat traced circuits have passed extensive field performance tests to initial use to demonstrate their ability to maintain fluid tempera-at a desired level above minimum anbient temperature.
It has been dernonst:::-ated that the protective measures discussed above are adequate to prevent failure or malfunction of components due to freezing.
This completes our revi:>w of our facilities and we have concluded that we have or will provide, as necessary, appropriate and adequate protection to prevent frozen lines.
SURRY PO',vER STATION RESPONSE TO IE BULLETIN )9-24 FROZEN LINES Attachment page 3 As directed by I.E. Bulletin 79-2!1, we have revie;.;recl our plant to determine that adequate protective measures have bi:en taken to ensure that safety-related process, instrument, and sampling lines do not freeze during extremely cold weather.
The review covered the period from January 1975 until the present time.
During this period the following events involving frozen lines occurred.:
DATE 12/19/75 1/14/77
... 2/11/79 COMPONENT Steam Genera tor "C" Pressure Transmitter 496, Unit 2 Flow Transmitter FT-CS-203, 204 Valve 2-PG-153 CAUSE Transmitter sensing line frozen due to abnormally cold outside air being drawn through louvers.
D/P Uni ts frozen Diaphram ruptured, frozen.
PROTECTIVE MEASURES Sealed intake louvers near transmitter.
Replaced failed strip heater.
Replaced the valve, in-clude. the area uhere th(*
valve is located in the Check-Off program.
Currently under development is a Cold Weather Protection Che.ck-Off Program which wil 1 include a coP.1.prehensive stat /.on verification of the status of any and all louvers, dampers and enviroTh~ental boundaries to ensure they are providing adequate protection against freezing conditions.
Also included in this prog;.au will be heat tracing circuits and insulation on all affected piping to verify its integrity.
7he proposed progra~ ~ill include the utilization of stand-by space heate:-s for use in areas w"hich are expected to be subjected to freezing condi-tio~s ~elated to abnormal operating or maintenance conditions.
It is our intention to implement the above program on or about November 9, 1979, with the Check-Off to be performed as soon after that date as practicable and as often as necessary based on the severity of weather condi-tions.