ML20081A059

Safety Evaluation Supporting Amends 203 & 181 to Licenses DPR-53 & DPR-69,respectively

ML20081A059
Person / Time
Site:	Calvert Cliffs
Issue date:	03/03/1995
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20081A058	List: ML20081A055 ML20081A059
References
NUDOCS 9503140458
Download: ML20081A059 (3)

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UNITED STATES S

NUCLEAR REGULATORY COMMISSION f

WASHINGTON, D.C. 20566 4001 k

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1 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 203 TO FACILITY OPERATING LICENSE NO. DPR-53 AND AMENDMENT NO.181 TO FACILITY OPERATING LICENSE NO. DPR-69 1

BALTIMORE GAS AND ELECTRIC COMPANY j

f CALVERT CLIFFS NUCLEAR POWER PLANT. UNIT NOS. 1 AND 2 l

DOCKET NOS. 50-317 AND 50-318 j

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1.0 INTRODUCTION

By letter dated August 2,1994, the Baltimore Gas and Electric Company (BG&E-or licensee) submitted a request for changes to the Calvert Cliffs Nuclear Power Plant, Unit Nos. I and 2, Technical Specifications (TSs). The requested changes would revise the TSs of the Calvert Cliffs Nuclear Power Plant, Unit 3

Nos.1 and 2, by including the emergency diesel generators (EDGs) high crankcase pressure trips in those trips which are provided to protect the EDGs from abnormal conditions during normal operations and which are bypassed during an accident condition. The high Jacket coolant temperature and'the low jacket coolant pressure, which are currently bypassed during an accident condition, are designed to. trip the EDGs to prevent damage and minimize out-of-service time.

However, these protective trips which are functional during normal operations are not r.1 ways indicative of imminent failure of an EDG and it is desir61e to bypast them during an accident condition tocassure that safety-related equipment necessary to mitigate the consequences of an accident has its required power source.

BACKGR0VND The safety-related function of the EDu-o provide power to the equipment necessary to safely shut down or mair.c ie unit (s) in safe shutdown during nonaccident conditions or to provide p.

to the Engineered Safety Features (ESF) equipment required to mitigate ' c

nsequences of design basis accident. The Calvert Cliffs site has three EDGs, with one EDG dedicated to each unit and its associated 4160 volt ESF buss, and the third EDG capable of j

being aligned to the second ESF buss of ether unit. Two of the three EDGs are capable of supplying power to the loads required to mitigate the consequences of an accident in one unit and safely shut down the other unit, thus the single failure criterion is met in that one of the three EDGs can fail and the plant can be maintained in a safe condition.

When a sustained undervoltage or loss of offsite power is sensed on the ESF busses with the dedicated EDGs, the associated EDG will start, the normal 9503140458 950303 PDR ADOCK 05000317 P

PDR

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source of power is disconnected, the bus is stripped of its loads, the EDG is connected to the bus, and a shutdown sequencer will sequentially load the equipment necessary to safely shut down the unit.

If an undervoltage is sensed on either of the ESF busses that is provided backup power by the swing EDG, the same sequence of events will occur with the swing EDG providing power to the ESF bus that had the low voltage.

In the event that both of the ESF busses that rely dn the swing EDG for backup power sense low voltage concurrently, the swing EDG will supply power to the ESF bus whose electrical under voltage signal is received first. The swing EDG can be manually transferred to the other ESF bus subsequent to the initial alignment.

Accident conditions will result in a Safety Injection Actuation Signal (SIAS) being initiated for the affected unit which will start the EDGs; however, the sequence of stripping and loading the required ESF equipment will not occur unless there is a loss of offsite power.

If the SIAS is concurrent with a loss of offsite power, a loss-of-coolant sequencer will perform the necessary functions to strip both ESF busses and load the required ESF equipment. The shutdown sequencer on the nonaccident unit will perform its function as previously described. Should a single failure occur in the nonaccident unit, the swing EDG can be manually transferred from the accident unit to the other ESF bus on the nonaccident unit.

3.0 EVALUATION As previously noted, the request is to add the high crankcase pressure trip as one of the EDG trips to be bypassed by a SIAS. The purpose of this EDG protective trip is to minimize engine damage as the result of failure mechanisms which produce a high crankcase pressure. BG&E and the EDG manufacturer, Fairbanks Horse, have identified five failure. modes which could result in a high crankcase pressure. These failure modes, which could occur as the result of a single random failure, are; i

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Broken piston rings 2.

Cracked pistons 3.

Blower seal failure 4.

Liner water seal failure i

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Failed crankcase vacuum system BG&E analyzed the consequences of each of the failure modes identified above.

The first four failures could lead to further degradation of the effected EDG.

The current protective trip would trip the affected EDG; however, the damage to the EDG would be such that the EDG would be out-of-service for an extended period of time to implement the necessary repairs. However, these failure i

modes would not lead to rapid destruction of an EDG.

The most common failure resulting in a high crankcase pressure, failed crankcase vacuum system, does not lead to further degradation.

BG&E noted that several EDG shutdowns have resulted from this type of failure during testing. BG&E identified problems with an oriface plate and condensate in the crankcase as the cause of the crankcase vacuum system problems and implemented

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' corrective actions / modifications which were completed in.1988. Since that time there has been one trip which was due to oil in a sensing line to the l

crankcase. This.was corrected last year and there have been no subsequent trips due to high crankcase pressure, j

Although the first four failures will result in damage to the affected.EDG, as

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previously noted, they do not lead to rapid destruction of_the diesel engine.

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A high crankcase pressure is annunciated in the control room, by any one of the three pressure. sensors, which alerts the operators of the abnormal

'l crankcase condition..BG&E will. modify the plant operating procedures to.

include monitoring the high crankcase pressure when a SIAS is present.. The

.j current procedures require that the other EDG protective trips that are bypassed when a SIAS is present be monitored. The additional requirement to i

monitor the crankcase high pressure will assure that the operator has l

sufficient time to react to unacceptable changes in this parameter.

j The Institute of Electronic and Electrical Engineers (IEEE) Standard 387-1984, J-

"IEEE Standard Criteria for Diesel-Generator Units Applied as Standby Power Supplies for Neclear Power Generating Stations," as augmented by Regulatory Guide (RG) 1.g, " Selection, Design, Qualification, And Testing of Emergency Diesel Generator Units as Class IE Onsite Electric Power Systems at Nuclear I

i Power Plants," provide guidance for bypassing EDG protective trips during i

emergency conditions. The guidance indicates that trips may be bypassed under accident conditions provided that the operator has sufficient time to react i

appropriately to an abnormal EDG condition.

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4.0 SUP91ARY As noted, BG&E has requested to modify TS 4.8.1.1.2.d.3.c surveillance requirements to include verification that the EDG high crankcase pressure i

trips are bypassed when a SIAS is present and the inclusion of footnotes i

indicating that the_ verification is not required on a particular EDG until the j

modification implementing the bypass has been completed for the EDG.

In-addition, the footnote will also indicate that the modifications will be completed by February 28, 1996. This request is based on the following:

1) a t

high crankcase pressure will not result in rapid destruction of an EDG, 2) the operators are alerted of_ the condition by a control room annunciator and the plant op'erating procedures will be modified to provide appropriate guidance to the operators, 3) allowing an EDG to operate with a high crankcase pressure condition will not impact the operability of the unaffected EDGs or other safety-related equipment necessary to mitigate the consequences of an accident assuring that the single failure criteria is met, and 4) the availability of the'affected EDG during the initial phase of an accident will be increased.

The above evaluation, as summarized, indicates that the proposed changes are consistent with the guidance provided in IEEE Standard 387-1984, as augmented by RG 1.9, and the proposed changes are supported by the EDG vendor; therefore, we find that the proposed changes are acceptable.

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5.0 STATE CONSULTATION

l In accordance with the Commission's regulations, the Maryland State official was notified of.the proposed issuance of the amendments. The State official had no comments.-

t 6.0 ENVIRoletENTAL CONSIDERATION The amendments change a requirement with respect to installation or use of a I

facility component located within the restricted area as defined in 10 CFR-i

.Part 20 and changes surveillance requirements. The NRC staff has determined that the amendments involve no significant increase in the amounts, and no

- i significant change in the types, of any affluents that may be released offsite, and that there is no significant increase in individual or cumulative i

occupational radiation exposure. The Commission has previously issued a i

proposed finding that the amendments involve no significant hazards consideration, and there has been no public comment on such finding (59 FR 47165). Accordingly, the amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(g). Pursuant to 10 CFR 51.22(b) no savironmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendments.

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7.0 CONCLUSION

The Commission has concluded, based on the considerations discussed above, that:

(1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendments will not be inimical to the common l

defense and security or to the health and safety of the public.

Principal Contributor:

D. Mcdonald Date: March 3, 1995 4

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