ML20059D769
| ML20059D769 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 12/17/1993 |
| From: | Denton R BALTIMORE GAS & ELECTRIC CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9401100068 | |
| Download: ML20059D769 (4) | |
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a BALTIMORE GAS AND ELECTRIC 4
1650 CALVERT CLIFFS PARKWAY. LtJSBY, MARYLAND 20657-4702 ROBERT E. DENTON Vict PRESIDENT NUCLE AR rNERGY December 17,1993 U. S. Nuclear Regulatory Commission Washington, DC 20555 ATTENTION:
Document Control Desk
SUBJECT:
Calvert Cliffs Nuclear Power Plant Unit No. 2; Docket No. 50-318 Emergency Diesel Generator Upgrade Project - Temporary Exemption Reauest
REFERENCE:
(a)
Letter from Mr. R. E. Denton (BG&E) to NRC Document Control Desk, dated August 17,1993, Emergency Diesel Generator Upgrade Project Pursuant to 10 CFR 50.12(a), Baltimore Gas and Electric Company requests a temporary exemption from the requirements of (draft) General Design Criter. - 2 or equivalent relief. This relief will
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permit the temporary removal of the steel missile dcx which provides missile protection for Emergency Diesel Generator (EDG) No.11 and support s, ccms common to the other EDGs. The missile door protects the EDG and support systems from the effects of severe weather events, such as tornados, which may affect the Calvert Cliffs site. Accordingly, temporary relief from GDC - 2 (1%7 draft) is requested as it relates to the design of a system essential to the mitigatior. of an accident to withstand the effects of natural phenomena. We have identified the need to remove the missile door approximately four times during the refueling outage for a period of about 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> each i
time.
As detailed below, this temporary exemption is necessary to permit upgrades to the EDG without a dual unit shutdown. Support systems common to all three EDGs run through the EDG No.11 room.
Therefore, removal of the missile door affects the missile protection for all three EDGs. Ik) wever, these modifications will result in an increased capacity for EDG No.11 following the ~ Unit I refueling outage (spring 1994). This increased capacity will provide operators with increased flexibility in the addition of discretionary post-accident loads. This enhances our ability to respond to transient events at Ca! vert Cliffs.
Baltimore Gas and Electric Company believes that the standards of 10 CFR 50.12 are satisfied in this case. Special circumstances are present, as described in 10 CFR 50.12(a)(2)(iv) and (v), to warrant granting the temporary exemption. This temporary exemption willindirectly result in benefits to the
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public from the increased capacity of one of the EDGs. The temporary exemption is requested for a speciGe period; at all other times the facility will be in conformance with the requirements of GDC-2 (draft). Baltimore Gas and Electric Company is committed to minimizing the time the missile door is removed.
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Document Control Desk December 17,1993 Page 2 IIACKGROUND General Design Criteria - 2 (1%7 draft) states, "Those systems and components of reactor facilities which are essential to the prevention of accidents which could affect the public health and safety or to mitigation of their consequences shall be designed, fabricated, and erected to performance standards that will enable the facility to withstand, without loss of the capability to protect the public, the additional forces that might be imposed by natural phenomena such as carthquakes, tornados, Ikxxling conditions, winds, ice, and other local site effects. The design bases so established shall reficet:(a) appropriate consideration of the most severe of these natural phenomena that have been recorded for the site and the surrounding area and (b) an appropriate margin for withstanding forces greater than those recorded to reflect uncertainties about the historical data and their suitability as a basis for design." As stated in our Final Safety Analysis Report submittal (1971) the plant design and construction proceeded based upon the intent of the draft GDC.
Our EDGs are systems which prevent and mitigate the consequences of an accident. The Calvert Cliffs site has three EDGs. Normally, EDG No.11 is dedicated to Unit 1, EDG No. 21 is dedicated to Unit 2, and EDG No.12 swings to the accident unit. Each EDG is enclosed in a separate room in the Auxiliary Building. He Auxiliary Building is a Class 1 structure, one of whose functions is to protect the EDGs and their support systems from tornado-borne missiles. Each of the EDG rooms was designed with a large opening on the western side to allow for movement of the diesel engine into or out of the room. These openings are covered by steel doors which provide missile protection equivalent to that provided by the concrete walls. Each of these rooms contains a diesel generator, its k> cal controls, and support systems. The room that contains EDG No.11 contains senice water piping which provides cooling water to EDG No.12 and the starting air header, which is common to all three diesel generators. In addition, EDG No.11 shares a common concrete block wall with EDG No.12, which is not designed to withstand missile impingement.
During the period of the exemption, Unit 1 will be defueled for the spring 1994 refueling outage.
Unit 2 will be operating in Mode 1. Unit 1 does not require an operable EDG while defueled.
Unit 2 requires two operable EDGs in Mode 1 (Technical Specification 3.8.1.1). Emergency Diesel Generator No.11 will be inoperable for the duration of the upgrade. Both EDG Nos.12 and 21 are l
operable for Unit 2. When the missile door is removed from the EDO No.11 room, the missile protection is also defeated for EDG No.12 because of the shared concrete block wall and the shared support systems contained in the EDG No.11 room. Missile protection is also defeated for EDG No. 21 because of the common starting air system present in the EDG No.11 room.
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Performance of the upgrade on EDG No.11 will entail removal and replacement of several large components on the engine. The following components are of a size and weight which makes rigging in and out of EDG No.11 labyrinth personnel door impossible, thereby requiring missile door removal:
Blower 42" x 40" x 48" 2400lbs Turbos (2) 28" dia. x 34" deep 1800 lbs Air Inlet Pipe 28" x 40" x 25" 430lbs Intercoolers (2) 15" x 15" x 59" 520lbs Heat Exchanger Tube 14" dia. x 95"long 1154lbs Bundles (2)
Drain Piping 10" dia. x 16' long 800lbs
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Document Control Desk December 17,1993 Page 3 The upgrade work has been scheduled to begin March 1,1994, and end on March 18,1994. Based on the current work scope, we expect to remove the missile door four times during the upgrade work.
Each removal is expected to be less than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> in duration. When the missile door is removed, it will remain connected to the crane used to remove it. This will permit rapid re-installation, if a
necessary. We are requesting a temporary exemption to GDC - 2 (draft) only for those periods when the missile door is removed from the opening to the EDG room.
i TIIE REOUIREMENTS OF 10 CFR 50.12 ARE MET The standards set forth in 10 CFR 50.12 provide that specific exemptions will be granted which:
are authorized bylaw; are consistent with the common defense and security; will not present an undue risk to the public health and safety; and
^f are accompanied by special circumstances.
Baltimore Gas and Electric Company believes that the activities to be conducted under the temporary exemption are clearly authorized by law and are consistent with the common defense and security. The remaining standards for the temporary exemption are also satisfied, as described below, i
No Undue Risk The temporary exemption will not present an undue risk to the public health and safety. The likelihood of missile damage to the EDGs resulting from natural phenomena is small at Calvert Cliffs during the period for which the exemption would apply. The risk is associated with tornado generated missiles. Calvert Cliffs has a defined " tornado season" when the probability of a tornado is greater than other periods. As defined in Technical Specification 3.8.1.1, tornado season extends from April 1 to September 1. Based on the current schedule, we anticipate all of the physical work (and therefore all of the missile door removals) to occur during the month of March. Therefore, the risk of a tornado occurring during the period we have the missile door removed is acceptably low, i
Baltimore Gas and Electric Company will take compensatory actions to reduce the risk of missile damage to the common EDG support systems for the period of the exemption. The removal of the missile door will be for such a short period of time that the missile door will remain connected to the.
crane used to remove it. While the missile door is removed, operations personnel will remain cognizant of approaching weather systems. Personnel responsible for supervising the installation of i
the modification will be notified if a tornado watch is issued for the plant site. If a watch is issued, a concerted effort will be made to reinstall the missile door before the arrival of the storm. This effort will be limited only by the need to ensure the safety of the individuals performing the work.
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Document Control Desk December 17,1993
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Special Circumstances His request involves special circumstances as set forth in 10 CFR 50.12 (a) (iv) and (v). The temporary exemption will indirectly result in benefits to the public from the increased capacity of EDG No.11. In addition, the exemption would provide only temporary relief from the applicable regulation. The temporary exemption is requested for a specified, limited period of time: about four times for approximately 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> each during the month of March 1994. Therefore, the exemption would provide only temporary relief for the period necessary to move equipment in and out of the room.
Without the requested exemption, it will not be possible to perform the upgrade work on the EDG t
without requiring the operating unit (Unit 2) to be shut down. We are committed to naaking good faith efforts to provide missile protection for the EDG support systems during the temporary exemption period. As noted above, we will be prepared to reinstall the missile door whenever there is a threat of a tornado at the Calvert Cliffs site. We are also limiting the amount of time the missile door is removed.
.SCIIEDUIE The first removal of the missile door is currently scheduled to take place on March 1,1994.
Therefore, we request that this temporary exemption be granted prior to that date.
CONCLUSION Baltimore Gas and Electric Company believes the standards of 10 CFR 50.12 are satisfied including the existence of special circumstances as required by 50.12(a)(iv) and (v). This temporary exemption is necessary to permit a desirable upgrade to the EDG without an unnecessary unit shutdown.
f Should you have any further questions regarding this matter, we will be pleased to discuss them with you.
l Very truly yours, 3
LLt for R. E. Denton Vice President - Nuclear Energy RED / PSF / dim cc:
D. A. Brune, Esquire J. E. Silberg, Esquire R. A. Capra, NRC D. G. Mcdonald, Jr., NRC T. T. Martin, NRC P. R. Wilson, NRC R. I. McLean, DNR
- 3. H. Walter, PSC
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