ML20004E123

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Forwards Summary of Util Assessment of Facility Emergency Procedures & Training Program Per NRC 810225 Ltr
ML20004E123
Person / Time
Site: Fort Calhoun Omaha Public Power District icon.png
Issue date: 06/05/1981
From: William Jones
OMAHA PUBLIC POWER DISTRICT
To: Eisenhut D
Office of Nuclear Reactor Regulation
References
NUDOCS 8106110198
Download: ML20004E123 (3)


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Omaha Public Power District 1823 MANNEY e OMAHA. NESRASMA 68102 8 TELEPMONE S36-4000 AREA CODE 402 June 5, 1981 Mr. Darrell G. Eisenhut, Director U. S. Nuclear Regulatory Commission Office of Nuclear Reactor Regulation Division of Licensing Washington, D.C. 20555

Reference:

Docket No. 50-285

Dear Mr. Eisenhut:

The Commission's letter dated February 25, 1981, asked all licen-sces to review current plant operations to determine their capability to mitigate a station blackout event. Omaha Public Power District has assessed the Fort Calhoun Station's emergency procedures and training program and a sumaary of this assessment is attached.

Sincerely, Q yE

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[.JW.C. Jones Division Manager

[y . J-, s Production Operations lS_j, l

JUN 10 E31 a 9 M'yykL '

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Attachment . 4' ,g /

cc: LeBoeuf, Lamb, Leiby & MacRae 1333 New Hampshire Avenue, N.W.

Washington, D.C. 20036 i

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s ASSESSMENT OF FORT CALHOUN STATION'S PROCEDURES FOR MITIGATING THE STATION BLACK 0UT EVENT The Fort Calhoun Station's emergency procedures were reviewed to determine their adequacy for mitigating a station blackout event. There are two emercency procedures that provide for actions in direct response to a loss of AC power. Emergency Procedure EP-3, " Complete Loss of Off-Site AC Power", details actions to be taken with total loss of off-site AC power with proper functioning of diesel generators to provide emer-gency AC power. Emergency Procedure EP-33, " Complete Loss of Off-Site and On-Site AC Power", provides operator actions when all AC power is lost. The District's evaluation of these procedures showed that the plant can be maintained in a safe shutdown condition for any loss of AC power event. Loss of all AC power will not preclude core cooling, since the steam driven auxiliary feedwater (AFW) pump requires only DC power for operation. Procedures for diesel restart provide adequate detail for operator actioas. The emergency procedures include precautions for protecting all vital components upon restoration of AC power by in-clusion in EP-3 or EP-33, or by reference to specific equipment pro-cedures that include all applicable precautions for individual component operation or restart. All plant operators are fully trained on these emergency procedures as part of their qualification and requalification program. Therefore, the District believes that the procedures and

-training provided to the plant operators ensure that all loss of AC power events will not endanger the integrity of the reactor core.

The District's " Load Shedding and Restoration Procedures" manual provides system operators detailed guidance for restoring the grid.

These procedures, as well as the system operator training program, emphasize the special power needs for the Fort Calhoun Station (FCS).

In the event the diesel generators fail to start at the FCS, system operators understand that restoring power to the FCS is the top pri-ority.

Also, as part of its evaluation, the District evaluated the time required to restore AC power. The basis for the estimated time avail-able to restore AC power is the time required before loss of the natural circulation driving head. The driving head would be lost as a result of loss of coolant inventory to below the hot leg nozzles. The loss of inventory results from reactor coolant pump seal leakage. Controlled bleedoff through the reactor coolant pump seals will continue upon loss of. all AC power. The seal bleed at 4 gpm, without an available charging pump, will eventually reduce core inventory to a point where natural circulation flow could be lost. The District has analyzed this concern and determined that it would take 8.8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> for total loss of pres-surizer level and another 11.2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> before level would be below the reactor vessel flange. After 20 hours2.314815e-4 days <br />0.00556 hours <br />3.306878e-5 weeks <br />7.61e-6 months <br />, there would still be sufficient coolant inventory to maintain natural circulation cooldown of the core.

The limiting factor on the secondary side would be steam generator

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dryout. However, the steam driven auxiliary feedwater (.AFW) pump can be operated with loss of all AC power and the diesel driven fire pump can be used to provide water to the emergency feedwater tank, to preciude steam generator dryout. Therefore, the plant will be maintained in a safe shutdown condition for more than 20 hours2.314815e-4 days <br />0.00556 hours <br />3.306878e-5 weeks <br />7.61e-6 months <br /> with all AC power lost.

In conclusion, the District believes that, in all aspects, the Fort Calhoun Station has instituted adequate measures for mitigating the station blackout event. No further action is required.

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