ML20203A131
| ML20203A131 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 02/04/1998 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20203A100 | List: |
| References | |
| NUDOCS 9802230279 | |
| Download: ML20203A131 (3) | |
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s NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. seseHoot
- sese SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION REGARDING THE EMERGENCY DlE8EL GENERATOR QUALIFICATION REPORT RALTIMORE GAS AND ELECTRIC COMPANY CALVERT CLIFF 8 NUCLEAR POWER PLANT. UNITS 1 AND 2 DOCKET NOS,50 317 AND 50-318
1.0 INTRODUCTION
On July 21,1988, Part 50 of Title 10 of the Code of Federal Renulations was amended to include a new Section 50.63, entitled " Loss of All Altemating Current Power," and referred to as the -
station blackout (SBO) rule. The 880 rule requires that each light-water cooled nuclear power p; ant be able to withstand and recover from an SBO of specified duration. The 3B0 rule also requires that information defined in the rule be provided to the staff for revicw. Baltimore Gas &
Electric Company (BGE) responded to the requirements of the rule, and the staff approved its response by letter dated February 12,1992. The staff's approvalincluded the addition of two new safety-related Class -1E emergency diesel generators (EDGs).
BGE submitted a revised response to the SBO rule on July 7,1993. One of the initial commitments approved by the NRC staff in its safety evaluation (SE) was the installation of twc.
safety-related EDGs, as noted above, which would have resulted in a total of five safety-related EDGs at the site. The revised response changed that commitment to add one safety-related and one nonsafety-related EDG. The nonsafety-related EDG will be utilized as an altemate ac power source during 8B0 coreditions. The final configuration includes two dedicated safety-related EDGs per unit. The revised response was approved by an SE dated September 22,1993.
Two of the three original safety-related EDGs have been modified to increase their rated capacity from 2500 kW to 3000 kW, which enhances tne overall reliability of the onsite electrical power distribution system. The third EDG will be upgraded during the upcoming Calvert Cliffs Unit 1 refueling outage.
By letter dated September 12,1997, as supplemented November 3,1997, and January 8,1998, BGE requested a temporary exempti'.n to General Design Criterion 2 (GOC-2), " Design Bases for Protection Against Natural Phenomena," to perform the upgrading of the Unit 1 EDG 1B. The exemption will permit the temporary removal of the steel missile doors that provide missile protection for Unit 1 EDG 1B, Unit 2 EDG 2A, and support systems common to Fairbanks Morse Unit 1 EDG 18 and Unit 2 EDGs 2A and 28. - The upgrade will be conducted during the upcoming Unit i refueling outage, wnich will commence on or about April 3,1998, and is scheduled to be completed in early June 1998.- The EDG upgraJe requires a total of four
- removals between the two missile doors during the upgrade work. Each removal is estimated to take less than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, which will result in removal of the missile doors for approximately 100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> during the scheduled 60-day refueling outage. During the temporary exemption period,
~ Unit 1 will be defueled for the 1998 refueling outage and Unit 2 will be operating. Unit 1 EDG 18 will be inoperable for the duration of the upgrade. Unit two requires two operable EDGs during power operation. Both Unit 2 EDGs,2A and 28, will be operable for Unit 2. When the missile door is removed from the Unit.1 EDG 1B room, the missile protection is also defeated for the 990223027 900204 PDR ADOCn OS 37 P
A-Enclosure
a 2-i Unit 2 EDG 2A because of the shared concrete block wall When the missile door for the Unit 2 EDG 2A room is remceed, missile protection is also defeated for Unit 1 EDG 1B (which is out of i
service) because of the shared concrete well. In addition, when either door is removed, missile
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protection is defeated for all three EDGs because of the common starting air system in both rooms.-
t 2.0 EVALUATION Although some increase in missile interaction risk will occur during Unit 2 operation and the refueling outage of Uriit 1, it will be minimal because the missile doors will be removed for only short periods. The steel missile doors must be removed a *otal of four times during the upgrade work. Each removal is expected to take less than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, resulting in the removal of the missile doors, for a total of approximately 100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> during the refueling outage. Only one door will be removed at a time. When a missile door is removed, it will be connected to the crane used to remove it. This step permits rapid reinstallation, if necessary. The licensee is requesting a temporary exemption from GDC-2 only for those periods when a missile door is removed from the opening to either EDG room. Thus, the likelihood of tomado-generated or other high wind-generated missile damage that could affect the exposed EDGs and the r,upport systwms for the exposed EDGs is low. Even though the added risk is small, BGE is providing compensatory j
action to ensure the safe operation of Unit 2 and refueling of Unit i during the short periods when each missile door will be removed. As previously indicated, a concerted effort will be made -
to reinstall the missile doors if a tomado watch or a hurricane watch is issued or if sustained i
winds are predicted to be greater than 50 miles per hour at the fite in accordance with the plant site Emergency Response implementation Procedure 3.0, Attachment 17. This measure will not only cover tomado conditions, but other severe weather conditions as well When the missile shield is removed, it is left connected to the crane used to remove it. A crane operator remains at the crane controls during the time the missile shield is removed. In addition to the crane operator, three people are used to handle the movement of the shield and fasten it in place.
These people are drawn from the crew working on the diesel upgrade since the shield is removed only when they are working in tne area. The time required to reinstall the missile shield is approximately 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> and 15 minutes. This time includes 30 minutes to 45 minutes to move and position the shield, and 30 minutes to completely torque a minimum of 13 bolts to hold it in place. The installation time is considered sufficient since plant procedures require that the
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missile shield be reinstalled on an adverse weather watch, rather than waiting until a waming is issued. The only factor that would impede the reinstallation of the missile doors would be the safety of the individuals performing the reinstallation. In addition, the licensee has stated that the door between EDG 1B room and the EDG 2A room is a fire barrier but not a flood barrier. The fire barrier will be breached when the door is removed to pass EDG parts through. Plant procedures require a fire watch if any barrier is to remain open.- These procedures will be followed for the period the door is removed. The staff has reviewed the licensee's proposed exemption from GDC 2, including the compensatory measures, and has concluded that the likelihood of missile damage to the operable EDGs and portions of the support systems is small during the period that the requested exemption would apply.
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3.0 CONCLUSION
On the basis of its review, the staff has concluded that the licensee's proposed temporary exemption from GDC-2 should be granted, This conclusion is based on the low probability of missile generation duririg ;he short period that the exemption would apply and on the compensatory measures Inst will be in place.
Principal Contributor: A. Dromerick Date:
February 4, 1998
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