ML20214H754
| ML20214H754 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 11/23/1986 |
| From: | Tiernan J BALTIMORE GAS & ELECTRIC CO. |
| To: | Thadani A Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20214H757 | List: |
| References | |
| NUDOCS 8612010014 | |
| Download: ML20214H754 (6) | |
Text
BALTIMORE GAS AND ELECTRIC i
CHARLES CENTER P. O. BOX 1475 BALTIMORE, MARYLAND 21203 JOSEPH A.TIERN AN VicE PREslDENT NUCLEAR ENERGY November 23,1986 U. S. Nuclear Regulatory Commission Office of Nuclear Reactor Regulation Washington, D. C. 20555 ATTENTION:
Mr. Ashok C. Thadani, Director PWR Project Directorate #8 Division of PWR Licensing-B
SUBJECT:
Calvert Cliffs Nuclear Power Plant Unit Nos.1 & 2; Docket Nos. 50-317 & 50-318 Emergency Request for Amendment Gentlemen:
The Baltimore Gas and Electric Company hereby requests an Amendment to its Operating License No. DPR-53 for Calvert Cliffs Unit No. I with the submittal of the proposed changes to the Technical Specifications.
PROPOSED CHANGE Change pages 3/4 8-5, 8-5a, and 8-7 of the Unit 1 Technical Specifications as shown on the marked-up copies attached to this transmittal.
STATEMENT OF EMERGENCY CIRCUMSTANCES The Technical Specifications involved would, unless amended, prevent Unit No. I from starting up on schedule. The conditions leading to this situation could not have been reasonably anticipated. It was originally anticipated that the inspection and overhaul of Nos. I1 and 12 diesel generators could have been completed during the current refueling outage for Unit No. I without impacting the critical path and delaying the startup. Since becoming aware of inspection and overhaul delays, we have acted promptly to request that the Technical Specifications be amended.
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c Mr. Ashok C. Thadani November 23,1986 Page 2 DISCUSSION This change proposes to allow CORE ALTERATIONS and positive reactivity changes on Unit No. I while in MODE 6 with no diesel generators (DG) available for emergency electrical power. We are currently in a scheduled refueling outage for Unit 1, and Unit 2 is operating at power. No.12 DG is undergoing an extensive period of inspection and overhaul and No.11 DG is temporarily aligned to Unit No. 2's electric distribution system in order to meet the Technical Specification requirements for MODE 1 full power operation.
Refueling of Unit No.1 is scheduled to commence on November 29, 1986. Based on previous repair and overhaul experience with the Nos.11 and 12 DGs, the maintenance on No.12 DG is not expected to be completed until November 29 at the earliest and December 6 at the latest. The current Technical Specifications require that an operable DG be available in MODE 6 in order to perform refueling operations and positive reactivity additions. In addition, they require that containment integrity in accordance with Technical Specification 3.9.4 be set without an operable DG.
Therefore, our Technical Specifications would prohibit refueling operations from beginning on November 29 and would continue to prohibit refueling until No.12 DG is overhauled and declared operable. Unless amended, the Technical Specifications would prevent Unit No. I from starting up on schedule.
The conditions leading to this situation could not have been reasonably anticipated. We performed an inspection and overhaul of No.11 DG earlier during our current outage.
Because the problems uncovered could not have been foreseen, the inspection and overhaul took longer than expected. We did not know until November 16, 1986, exactly how long the overhaul would take and when the effort on No.12 DG could actually start. We elected to overhaul No.11 DG first in order to defuel simultaneous with the overhaul. Refueling operations are critical path.
Based on our new experience and the slippage in schedule as a result of No.11 DG's extended out-of-service period, we do not believe we can perform a satisfactory inspection and overhaul of No.12 DG without postponing the scheduled startup because of constraints in the current Technical Specifications. The inspection and overhaul of No.11 DG took 17 days to complete, working seven days a week and two 10-hour shif ts per day.
We will perform additional maintenance on No.12 DG beyond what was originally anticipated for No.11 DG. We anticipate that the work on No.12 DG could take as long as 20 days. We started work en No.12 DG on November 16,1986. In order to continue with the scheduled work on No.12 DG simultaneous with the refueling of Unit No.1, we would need a one-time change to the Technical Specifications, as noted on the attached marked-up copies. We propose that the requested Technical Specification changes expire before draining the Refueling Pool while in MODE 6.
Mr. Ashok C. Thadani November 23,1986 Page 3 Mitizatina Features We will maintain the 69 kv SMECO power circuit operable onsite during the period of this emergency Technical Specification change. We will energize the 13 kv bus No. 23 with SMECO power by shutting breaker No. 252-2301, isolate it from all other buses, and open the feeder from No. 23 bus to our warehouse. The warehouse will be powered through t
alternate feeders. The appropriate procedures exist and our operators possess adequate
' knowledge and training to perform such an electrical line-up.
Additionally, plant personnel have been trained on the procedure to use the 69 kv SMECO offsite power circuit to power the emergency plant loads via the No. 23 bus. This power source is capable of handling all of the safe shutdown loads at the site and it is a fully qualified GDC-17 power source. Aligning this source, such that it is readily available, compen-sates somewhat for the unavailability of the DG.
We currently have a portable,1000 kw, 480-volt, Cummins Model KTA-50-G1 DG on site. This DG could be electrically connected to the vital 480-volt AC bus No.14A for Unit No.1.
Plant personnel have recently been trained to electrically connect this portable DG to the appropriate bus. In this configurstion, the portable DG would be used mainly for battery charging.
The Calvert Cliffs DC electrical power system (including the batteries, the battery chargers, and the inverters) is common to Units 1 and 2. In the event that only a single DG remained operable following a loss of offsite power (LOSP), it could provide battery charging that serves both units. Without charging, sufficient battery capacity would be available for approximately four hours.
As a final mitigating action, we intend to set containment integrity, as defined in i
Technical Specification 3.9.4, within four hours af ter a LOSP. In addition, we will maintain the Reactor Coolant System temperature less than 100 F while moving fuel during the time No.12 DG is inoperable. This is to ensure that an adequate temperature margin is maintained below 140 F.
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Deterministic Analysis Description L
Although not a design basis event, a deterministic analysis was performed assuming a LOSP while refueling Unit I with No.12 DG out-of-service. In addition, we assumed that Unit 2 was operating at 100% power and that one of the two remaining DGs (Nos.11 & 21 DGs) failed to start when the LOSP occurred. Furthermore, we assumed that offsite AC power would be restored within four hours following the LOSP.
l The four-hour restoration time assumed above is supported by several NRC and industry sources. In NUREG-1109," Regulatory Analysis for the Resolution of Unresolved Safety Issue A-44, Station Blackout," the median restoration time for offsite power was given as
Mr. Ashok C. Thadani November 23,1986 Page 4 about one-half hour, with 90% of the losses being restored in three hours or less.
NUREG-1032, " Evaluation of Station Blackout Accidents at Nuclear Power Plants,"
includes graphs that display the probability of restoring offsite power following plant-centered and grid-related losses. Figures A.2a, A.2b, and A.4 in NUREG-1032 show that greater than 90% of the losses can be restored within four hours. These data are consistent with the conclusions of NSAC-103, EPRI's study of LOSP events. In addition, our grid system studies show that at least one of our 500 kv power lines will be restored within four hours following a loss of offsite power. The system restoration study for PEPCO's electrical system was reviewed. In this study, SMECO is identified as a portion of PEPCO's load that would be restored early, within two hours if possible, during their system restoration. Therefore, we feel a four-hour restoration time for offsite power is both realistic and reasonable.
Analysis Results No analyses were required for Unit No. 2, since no change from current Technical Specifications are needed. The analyses we performed only address refueling MODE events for Unit No.1. It should be noted that the LOSP event is not required to be part of the plant's design basis accident analysis for refueling MODE events. These following evaluations were performed to verify that the plant could reasonably mitigate these events under a LOSP condition which lasts four hours. The FSAR Chapter 14 events that apply during MODE 6 are the Boron Dilution and Fuel Handling Incidents. The Boron Dilution Event was eliminated because the Refueling Pool level will be elevated so that offsite power is required to initiate the event.
We have evaluated the fuel handling incident under LOSP conditions assuming the iodines present after 36 days of decay. This is based on the earliest projected date for fuel movement from the Spent Fuel Pool into the reactor core. In addition, we have reviewed our ventilation and containment integrity requirements for the postulated accident. We have concluded that the existing FSAR analysis bounds the postulated offsite releases for the fuel handling event.
We also evaluated the effect of a LOSP on Spent Fuel Pool and Refueling Pool cooling for MODE 6. The analysis calculated the time it would take for the water in the reactor vessel and Refuelin5 ool to heat up from 100 F to 140 F following a LOSP. We P
determined that 140 F would not be exceeded within four hours, but would take greater than 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br />. We also calculated the time it would take for the Spent Fuel Pool to reach 155 F from its normal temperature. This time exceeded four hours (actual time is greater than 13 hours1.50463e-4 days <br />0.00361 hours <br />2.149471e-5 weeks <br />4.9465e-6 months <br />). In each case, we conservatively assumed the heat load from a full core, 30 days after shutdown, was present. The Spent Fuel Pool calculation also accounted for existing spent fuel present in storage. The results of each calculation showed that the specified temperature values were not exceeded within four hours.
An electric load analysis has been performed to evaluate the power requirements on the batteries to maintain the plant in a safe condition until offsite power is restored following a LOSP. We have found that enough power and generating capacity would be available to power the necessary loads for four hours. These loads are sufficient to set
Mr. Ashok C. Thadani November 23,1986 Page5 and maintain containment integrity in accordance with Technical Specification 3.9.4, provide adequate ventilation and lighting, and supply the appropriate instrumentation.
Additionally, we evaluated the boron stratification phenomenon and its likelihood given a LOSP. We found that sufficient natural circulation should be present in the refueling pool from the calculated decay heat load to preclude stratification during the four hours before power restoration. This assumed a full core in the reactor vessel to provide maximum resistance to recirculation flow through the core.
Technical Specification 3.8.2.2 requires that an OPERABLE DG be aligned to specific AC electrical buses or else have containment integrity, in accordance with Technical Specification 3.9.4, set within eight hours. We propose to change the requirement to four hours following a LOSP. Without a DG available, the 120-volt AC Vital Buses remain energized, drawing power from the batteries via the inverters. The 1 MW portable DG can supply a 480-volt Emergency Bus, and therefore, can charge a battery. We will maintain the SMECO 69 kv line in an operable status which is beyond what is normally required.
DETERMINATION OF SIGNIFICANT HAZARDS This proposed change has been evaluated against the standards in 10 CFR 50.92 and has been determined to involve no significant hazards considerations, in that operation of the facility in accordance with the proposed amendment would not:
(i) involve a significant increase in the probability or consequences of an accident previously evaluated; or A review of the Updated FSAR revealed that there were no design bases events directly affected by this change.
(ii) create the possibility of a new or different type of accident from any accident previously evaluated; or No new or different type of accident will be created by this proposed l
change. We evaluated, under LOSP conditions, the boron dilution and
(
fuel handling incidents, and the potential for boron stratification.
(iii) involve a significant reduction in a margin of safety.
This change does involve an incremental reduction in the margin of safety. However, this reduction is not considered significant based on the deterministic analysis performed.
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m Mr. Ashok C. Thadani November 23,1986 Page 6 SAFETY COMMITTEE REVIEW These proposed changes to the Technical Specifications and our determination of dgnificant hazards have been reviewed by our Plant Operations and Off-Site Safety Review Committees, and they have concluded that implementation of these changes will not result in an undue risk to the health and safety of the public.
FEE DETERMINATION Pursuant to 10 CFR 170.21, we are including BG&E Check No. (1908041) in the amount of
$150.00 to the NRC to cover the application fee for this request.
Very truly yours, c/ECM STATE OF MARYLAND :
TO WIT:
CITY OF BALTIMORE :
Joseph A. Tiernan, being duly sworn states that he is Vice President of the Baltimore Gas and Electric Company, a corporation of the State of Maryland; that he provides the foregoing response for the purposes therein set forth; that the statements made are true and correct to the best of his kr.owledge, information, and belief; and that he was authorized to provide the response on behalf of said Corporation.
WITNESS my Hand and Notarial Scal:
wed M Iw
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Notary Public My Commission Expires:
/j/M8 N. a1/f/6, Dat'e 3AT/SRC/ dim Attachments cc:
D. A. Brune, Esquire
- 3. E. Silberg, Esquire S. A. McNeil, NRC T. Foley, NRC