ML20086M720
| ML20086M720 | |
| Person / Time | |
|---|---|
| Site: | Waterford  |
| Issue date: | 02/09/1984 |
| From: | Gerrets T LOUISIANA POWER & LIGHT CO. |
| To: | Jay Collins NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| References | |
| 142, W3K84-0293, W3K84-293, NUDOCS 8402170019 | |
| Download: ML20086M720 (3) | |
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s am LoulSIANA 24a OaAnoNOe Srneu POWER & L1GHT P O BOX 6008. NEW ORLEANS LOUISIANA 70174. (504) 366 2345
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February 9, 1984 W3K84-0293 Q-3-A35.07 IN Ij E8 $4 Y J,
l Mr. John T. Collins Regional Administrator, Region IV FEB l 3 M U. S. Nuclear Regulatory Commission M
611 Ryan Plaza Drive, Suite 1000
- ~
Arlington, Texas 76012 l
REFERENCE:
Telecon C. Hooper (LP&L) and W. Crossman (NRC IV) on January 4, 1984.
Dear Mr. Collins:
SUBJECT:
Waterford SES Unit No. 3 Docket No. 50-382 Potentially Reportable Deficiency No. 142
" Dry Cooling Tower 'A' Freeze Damage" Final Report On January 4, 1984, a problem of freeze damage to the Dry Cooling Tower was reported as Potentially Reportable Deficiency No. 142.
Further evaluation of the previously described condition indicates this condition is not considered reportable pursuant to the requirement of 10CFR50.55(e).
E"ALUATION Following subfreezing weather at the plant site on December 26, 1983, it was discovered that several cells in dry cooling tower "A" had frozen and that this freeze had rn ulted in damage to the plates and the corner seam welds in the upper water boxes causing them to leak.
It appeared that the freezing in the cooling tower "A" occurred due to an insufficient flow of water through the tower coils in the freezing weather. The cooling tower "A" bypass valve was open at the time to maintain a temperature above 60 F in the Component Cooling Water System. This action resulted in lowering the CCW flow through the tower "A" coils to an insignificant amount. This in turn led to freezing of water in several cells of the tower.
SAFETY EVALUATION Water flow through the cooling tower can only be reduced to the point where it 1s susceptible to freezing when 1) the Cc;ponent Cooling Water System (CCWS) l is shutdown or; ii) the cooling tower bypass valve is in a substantially open position or; iii) when a specific Cooling Tower bay is isolated for maintenance.
8402170019 840209 PDR ADOCK 05000382 S
PDR 1"
1 0
s Mr. John T. Collins February 9, 1984 W3K84-0293 Page 2 Condition (1) can h'appen only when the plant is in cold shutdown mode (See Tech. Spec 3.7.3).
Condition (ii) can also occur only when the plant is in cold shutdown mode since, at all other times there is a significant heat load on the CCWS from the minimum loads required to be operating (See FSAR Table 69.2-3), which will preclude opening the CT bypass valves by any substantial amount.
Condition (iii) can occur during plant hot operating conditions (Modes 1 through 4) and can result in a loss of the isolated cooling tower bay.
Technical Specifications (3/4.7.4), however, preclude operation when less than the required number of wet / dry cooling tower cell combinations are available to operate and safely shutdown the plant under all emergency conditions assuming a total failure of one of the redundant wet / dry cooling tower divisions. Thus, if any dry tower bays were taken out of service and CCW flow isolated, thereby making the out-of-service bays susceptible to such damage, these technical specifications would ensure that sufficient heat sink capacity was still available to operate the plant safely under the aforementioned conditions.
It is thus not credible that a sequence of events could have occurred after fuel load in an operating plant such that similar damage would be incurred and leave the plant with insufficient heat sink capacity to safely operate and shutdown even assuming a coincident emergency and single active failure.
The final question that remains to be addressed to determino reportability is the following.
It is possible that during a cold shutdown or refueling shutdown condition (Modes 5 and 6), that freeze damage could occur in an isolated or stagnant bay and not be detected until the plant is restarted?
This is not considered credible. Surge tank level would quickly indicate any leakage. Alarms are provided and at lo level, make-up would be provided via the primary water pumps; at lo-lo level the leaking dry tower would be isolated.
If the leak were severe enough, the trains would be isolated and about 500 gpm safety grade CCW make-up actuated.
Presently, additional freeze damage problems have not been identified. 'If additional problems occurred they will be reported separately. Based on the
'above, this PRD is considered not reportable.
Very truly yours, th Yb5
>VvvCb; T.:F. Gerrets Corporate Quality Assurance Manager TFG:CNH:JC c..
A e.
l' Mr.' John T.' Collins February 9, 1984 W3K84-0293 Page 3 cc: Director Office of Inspection & Enforcement U. S. Nuclear Regulatory Commission Washington, D.C.-
20555 (15 copies)
- Director Office of Management Information and Program Control U. S. Nuclear Regulatory Commission Washington, D.C.
20555 Mr. E. L. Blake Shaw, Pittman, Potts, & Trowbridge 1800 M Street, N.W.
Washington, D.C.
20036 Mr. W. M. Stevenson Monroe & Lemann 1424 Whitney Building New Orleans, Louisiana 70130 Records Center Institute of Nuclear Power Operations 1100 Circle 75 Parkway, Suite 1500 Atlanta, Georgia 30339 N
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