ML19289E159
| ML19289E159 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 03/27/1979 |
| From: | Gilleland J TENNESSEE VALLEY AUTHORITY |
| To: | Stello V Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 7904030271 | |
| Download: ML19289E159 (3) | |
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TENNESSEE VALLEY AUTHORITY CHATTANOOGA. TENNESSEE 374of 500C Chestnut Street Tower II March 27, 1979 Mr. Victor Stello, Director Division of Operating Reactors Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, DC 20555
Dear Mr. Stello:
By my letter of March 13, 1979, we informed you that motors used on certain valve operators in the coatainment area of Browns Ferry Nuclear Plant which are not qualified for use in a LOCA environment. Enclosed is the required 14-day followup report which discusses the service requirements of these valve operators in the LOCA environment. We have concluded that no safety concern exists at this time. However, we are continuing to investigate the matter.
Very truly yours,
'l
')2I
.;[?g J. E. Gilleland 4
Assistant Manager of Power Enclosure cc:
Mr. James P. O'Reilly, Director (Enclosure)
Office of Inspection and Enforcement U.S. Nuclear Begulatory Commission Region II - Suite 3100 101 Marietta Street Atlanta, Georgia 30303 790403T127/
An Equal Opportunity Employer
ENCLOSURE FOLLOWUP REPORT REQUIRED BY IE BULLETIN 79-01 REGARDING ENVIRONMENTAL QUALIFICATION OF MOTORS USED ON CERTAIN VALVE OPERATORS - BROWNS FERRY NUCLEAR PLANT (
REFERENCES:
J. P. O'REILLY'S LETTER TO H. G. PARRIS OF FEBRUARY 8, 1979, AND J. E. GILLELAND'S LETTER OF MARCH 13, 1979, TO V. STELLO)
The motors on FCV l-55, Inboard Main Steamline Drain Valve, and FCV 74-78, Inboard RHR Head Spray Valve, are wound with Class B insulation which has a maximum continuous temperature rating of 239 F.
These valves are located in the primary containment and wouId be exposed to temperatures in excess of the insulation rating during a postulated LOCA; thus, long-term operability of the subject valves cannot be ensured.
However, as explained below, the service requirements of these particular valves during the LOCA are very low.
FCV l Inboard Main Steamline Drain Valve (IMSDV)
FCV l-55 is the Inboard Steamline Drain Valve in series with the respective outboard valve, FCV l-56.
This three-inch line allows draining of the main steamlines as the containment low point during cold reactor starts and is also used to pressurize the main steamlines before opening the MSIV's (Main Steam Isolation Valves) at hot standby conditions.
This valve is not a part of the ECCS systems.
FCV l-55 is classified as a primary containment isolation valve,
..a w 71 be signaled to close at the onset of a postulated LOCA. We beli<ve that the aced for environmental qualification at this time is unnece ssary for the following reasons.
1.
FCV 1-55 is ont open except at vary low reactor powers (i.e., normally closed);
2.
The outboard isolation valve FC" 1-56 is outside containment and will ensure in lation of the drain line.
However, since the subject valve is a containmeat isolation valve, TVA will replace the present Class B insulation wito environmentally qualified i
insulation at the ntxt refuel outare.
In the irterim, we will restrict operation of FCV 1-55 to the minimtm required fcc plant operation. This valve is normally closed. However,it is necessary to briefly operate FCV 1-55 during reactor startup or following reactor isolations in order to equalize steam pressure in the mainsteam li,e.
Therefore, the valve will be opened only for the situations described above (and will be under continuous surveil-lance during these periods) and cl ased and deenergized (i.e., tagged.out) at all other times.
s
, 'I
. FCV 74 RilR IIcad Spray Valve FCV 74-78 is part of the Residual IIcat Removal (RilR) shutdown cooling sub-system. Theoretically, it may be used to regulate the temperature of the upper vessel plenum by directing a small amount of spray water into the vessel head region during reactor cooldown. This valve cannot be opened if the vessel pressure is above 100 psig, which is the shutdown cooling inter-lock setpoint. At Browns Ferry we do not use the head spray mode of the R!lR; therefore, FCV 74-78 is never opened.
This valve is not associated with the LPCl mode of the RHR system and does not in any way function as part of the ECCS systems. The only possible safety concern arises from the fact that FCV 74-78 is classified as a primary containment isolation valve. Ilowever, as explained above, this valve is not used during operations at Browns Ferry.
Furthermore, the valve cannot be opened above 100 psig reactor pressure.
However, the RllR licad Spray Valve will be deenergized (i.e., tagged out) at all other times.
.