IR 05000317/1993004
| ML20035F711 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 04/13/1993 |
| From: | Bhatia R, Ruland W NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | |
| Shared Package | |
| ML20035F709 | List: |
| References | |
| 50-317-93-04, 50-317-93-4, 50-318-93-04, 50-318-93-4, NUDOCS 9304220193 | |
| Download: ML20035F711 (7) | |
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U.S. NUCLEAR REGULATORY COMMISSION
REGION I
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REPORT / DOCKET NOS.: 50-317/93-04 50-318/93-04 LICENSE NOS.:
DPR-53 DPR-69 LICENSEE:
Baltimore Gas and Electric Company MD Rts 2&4, P.O. Box 1535 Lusby, Maryland 20657 FACILITY NAME:
Calvert Cliffs Units 1 and 2 i
INSPECTION DATES:
February 1 - 5, 1993 4AMM 3fn/%
INSPECTOR:
R. Bhatia, Reactor Engineer, Electrical Section Date Engineering Branch, Division of Reactor Safety
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APPROVED BY:
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William H. Rulan'd, Ch'ief, Electrical Section Date #
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Engineering Branch, Division of Reactor Safety
Area Insnected: This was an announced inspection to review the licensee's corrective action
on previously identified inspection findings.
j Results: No violations or deviations were identified during this inspection. Of the five open
items reviewed in Units 1 and 2, four items were closed. One remaining unresolved item l
was updated. These items are discussed in Section 2.0 of this report.
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9304220193 930413 PDR ADOCK 05000317 PDR
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DETAILS 1.0 PURPOSE The purpose of this inspection was to review and verify the licensee's corrective actions for findings identified by the NRC during the 1992 Electrical Distribution Systems Functional Inspection (EDSFI) for Calvert Cliffs Unit I and 2. The review included the licensee's actions, addressed in their written responses to the EDSFI report dated July 8, August 14, and September 9,1992 and to the Notice of Violation, dated September 3,1992.
2.0 FOLLOW-UP OF PREVIOUS IDENTIFIED FINDINGS (UhTT 1 and 2)
2.1 (Closed) Violation Item Nos. 50-317/92-80-004 and 50-318/92-80-004 During the previous EDSFI inspection, the team identified a design concern with the operation of a load sequencer unit. The load sequencer logic was designed with two different inputs to the final actuation devices, a " time signal" from the sequencer, and a
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" process signal" from the Engineered Safety Feature Actuation System (ESFAS) logic to start the safety motor loads. The team was conce.rned that the process-controlled signals could become available after the sequencer signals and result in more than one load group being applied on the emergency diesel genemtor (EDG) at the source time. This condition could result in an unacceptable voltage dip on the emergency diesel generator output. In addition, since the same parameters are used to load both EDGs, this condition could result in the loss of both EDGs in the middle of a loss-of-offsite power (LOOP)/ loss of coolant incident (LOCI) event.
The licensee modified the load sequencing logic to prevent an unacceptable ' rop in EDG d
output voltage. The LOCI sequencer starts upon a receipt of either a safety injection
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actuation signal (SIAS) or an undervoltage (UV) signal. No additional process signals are required to start the required safety-related motors. Other minor logic changes also were made to further ensure that the LOCI sequencer steps worked properly.
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The inspector n: viewed selected documents and examined plant equipment to verify the completion and adequacy of the licensee's actions. The documents reviewed included:
Modification Package FCR-92-0210 for Units 1 and 2 e
Records for the 10 CFR 50.59 enhancement program training e
e Records for Generic Letter 91-18 training Records of the probabalistic risk assessment (PRA) review for problems similar to the o
EDG concern e
Modification 10 CFR 50.59
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Evaluation of motor starting capability during EDG transient conditions study
Industry Information Processing Procedure (IOER-01)
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The inspector concluded that the licensee's actions and training were comprehensive and that the modifications corrected the safety concerns regarding the LOCI sequencer design. This
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item is closed.
2.2 (Closed) Unresolved Item Nos. 50-317/92-80-013 and 50-318/92-80-013 This item pertains to the concern of a failure of the nonsafety-related heaters which are
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required to warm the intake air and maintain adequate ambient temperature in the battery rooms of both units. The intake dampers in these rooms are rearranged in the winter to
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ensure that very cold outside air is not drawn into the ducting system. If the nonsafety-related heaters fail, battery electrolyte temperature could decrease to an unacceptable level.
Typically, battery capacity decreases with a decrease in temperature. The EDSFI team was concemed that battery room temperatures may fall below 69*F, which was assumed in the t
battery sizing calculation. There is no alarm to alert the operating staff. The battery rooms are visited routinely only at the beginning of a twelve-hour shift. No procedure was in place to cope with this event.
The licensee installed temperature switches in each battery room (modification l
FCR 89-62). These temperature switches provide remote annunciatie
'n the control room.
The alarm is presently set for high (95 F) and low (71 F) room temieratures with a tolerance of i 2 F. Also, the licensee was evaluating whether the existing minimum temperature (67.5'F) could be changed by reducing the existing conservative margins assumed in the present calculation.
The inspector's review of the design documentation and test data, and field verification of the modification, revealed no concerns. Based on the above corrective action taken by the j
licensee, this item is closed.
2.3 (Closed) Unresolved Item Nos. 50-317/92-80-015 and 50-?' 3/92-80-015
This item pertains to the inadequate conductor temperature considered by the licensee in the j
de battery system voltage profile calculation. The EDSFI team identified that the licensee's voltage drop calculation (E89-42, Revision 0) considered all cable temperatures to be 25*C instead of the more likely temperature of 75*C. This assumption was considered unacceptable and nonconservative.
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During this inspection, the inspector determined that the licensee had revised the de voltage profile study. The calculation, E89-42, Revision 1, " Excessive Voltage Drop in DC i
Systems," hul been reissued on January 29,1993.
The inspector's review of the above calculation revealed that the revised calculation assumed a cable temperature of 75'C. A review of random selected cable impedance data identified no deficiencies. The inspector also noted that the calculation assumed the worst case scenario - the maximum loading of Bus 11 with the minimum voltage (105 V). All safety loads had adequate voltage; however, some nonsafety-related circuit components were slightly below their manufacturer's minimum published values. A review of the licensee's analysis for the nonsafety-related components confirmed that they were nonessential and were not required during the Loss-Of-Offsite Power and/or Loss-Of-Coolant Accident (LOCA)
conditions. The voltages for these devices would momentarily drop below the
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manufacturer's published value and recover soon after the LOCA loads accelerate.
Based on the above corrective action to demonstrate that all safety-related de components are functional under the worst case voltage drop condition and that the nonsafety-related devices were nonessential to the accident mitigation, this item is closed.
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2.4 (Closed) Unresolved Item Nos. 50-317/92-80-011 and 50-318/92-80-011 This item pertains to an inadequate design of the swing emergency diesel genemtor unit.
The EDG 12 swing unit is designed to start on an undervoltage signal, but does not align itself automatically to a bus. In addition, the service water pumps in the two trains do not align themselves to cool this diesel until the unit is connected on to either bus. Therefore, the swing EDG runs at idle condition without cooling water until the operator closes the
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EDG supply breaker to one of the two safety-related busses. The EDSFI team was concerned that: (1) in the event of a LOOP with a LOCA on one unit, the other unit could experience a temporary statie n blackout, if it also experienced a single failure of the only available EDG to it; and (2) in the event of a LOOP without LOCA, EDG 12 without cooling water could automatically shutdown on high temperature. In that case, a delayed i
LOCA affecting either unit could result in that unit being vulnerable to a single component failure.
During this inspection, the inspector noted that the licensee had completed their initial evaluation and initiated an interim action to provide administrative control. The licensee had
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evaluated the EDG heat removal rate under zero load condition and concluded that the EDG could operate approximately 10 minutes without service water cooling. The analysis assumed that the heat removal rate was linear and used manufacturer's data at various load conditions. The 10 minute rating of the diesel without cooling water was verbally confirmed by the manufacturer. The inspector also determined that the control room shift turnover
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instruction sheet directs the operators to connect the swing EDG onto either bus within 1 - 5 minutes of the EDG start. The inspector's discussion with the shift supervisor about this requirement revealed that this administrative contml step would continue until all applicable EOPs and AOPs operator training are completed. The review of both units EOPs (EOP-O, Rev. 2) found that instructions in step IV had been added to close the associate EDG output breater upon loss of power. The EOP operator training had been completed, and the procedures have been in effect since June 30,1992. Regarding the AOPs (AOP-3F), the inspector found that, in Step IV, the necessary instructions to close the idling swing EDG to the associated bus had been added. Both Unit 1 and Unit 2 procedures had been issued on December 3,1992. However, the operator training was scheduled to be completed by July 1993. The AOP procedure will become effective upon completion of this training. The EOPs are used during plant operating modes 1 and 2, whereas AOPs are used during plant conditions mode 3 through 6.
The inspector's review of applicable analyses revealed that the licensee has evaluated in their FSAR, Section 14.10, a case where it was assumed that operator action was required, at 10 minutes, to operate manually the auxiliary feedwater systems, in the event of a LOOP. In addition, FSAR Section 8.4.1, states that the EDG can operate at full load for three minutes before tripping on high temperature, assuming an initial jacket temperature of 140 - 145*F.
i Based on the licensee's assessment that the EDG can run without cooling for 10 minutes without tripping, the above short-term corrective actions, and the long-term ongoing EDG modification to add two 5000 kW, Class IE EDGs, the inspector concluded that the above team concerns had been adequately addressed. This item is closed.
2.5 (Open) Unresolved Item Nos. 50-317/92-80-012 and 50-318/92-80-012 This item pertains to a deficient surveillance test program on the air supply check valves which are part of the EDG starting air system. The EDSFI team was concerned that, every time a compressor starts, the air supply check valves chatter in response to pressure transients from the positive displacement pump. These check valves separate the non-1E
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safety-related compressor piping from the downstream safety-related piping system.
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During this inspection, the inspector noted that the licensee had issued an Engineering Test Procedure 92-95R, effective December 12,1992, and Technical Procedure, Valve-53, effective January 7,1993. Procedure 92-95R tests the check valve performance. Procedure i
Valve-53 provides instructions for disassembly, inspection, repair, and assembly of these valves and others. The contents and steps of these procedures were considered thorough and
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adequate. Discussion with the licensee and records reviewed revealed that maintenance work
orders have been prepared and scoped to be implemented during the Unit 2 upcoming outage, in spring 1993. The spare parts were on order and expected to arrive at the site by the end i
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of February 1993. Based on the evaluation /results obtained from the Unit 2 work, the licensee expects to establish a periodic monitoring of these check valve with appropriate
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procedures. This item will remain open pending NRC review of established procedures and l
successful inspection results confirming the function of these valves.
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2.6 (Closed) Unresolved Item Nos. 50-317/92-80-016 and 50-318/92-80-016 (listed in
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the previous report as "92-80-06" instead of "92-80-016")
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During the EDSFI inspection, the team was concerned that the control room HVAC air
compressor motor current, at its running voltage of about 85% of nameplate value, was high
enough and close to the trip region of the upstream breaker protection zone. The concern j
was that the circuit breaker for the Control Room Compressor motor may trip prematurely.
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l The licensee, using testing and calculations for the installed motor, found that adequate l
margin existed between the running current at degraded voltage and the breaker trip setpoint.
-l The test showed that the full load current at nominal voltage was 95 amperes. Assuming a
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degraded voltage of 85% of nominal value, the licensee calculated the motor running current
to be 112 amperes. This correlated to a trip margin of 161%, based on a 180 ampere
.i minimum breaker trip point. A similar analysis also showed that other typical 100 Hp motor j
i had running currents also low enough to prevent inadvertent breaker trips. Nonetheless, the
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licensee is considering increasing the current margin in their upcoming outages for both unit I
f compressor motors.
The inspector verified the licensee's conclusion through review of test data, calculations, and the documented engineering evaluations. Based on the newly established margin, this item is j
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closed.
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3.0 UNRESOLVED ITEMS-t
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Unresolved items are matters about which additional information is necessary in order to determine whether they are acceptable or they constitute a violation. Several unresolved items are discussed in detail under Section 2.0.
4.0 EXIT MEETING l
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The inspector met with the licensee's personnel denoted in Section 1.0 of this repmt at the
conclusion of the inspection period on December 5,1992. At that time, the scope of the
inspection and the inspection results were summarized. At no time during the inspection was.
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written material given to the licensee.
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Attachment: Persons Contacted l
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ATTACHMENT 1 Persons Contacted
Baltimore Gas and Electric Company
+ Boltner, R., Sr. Electrical Engineer - NES r
+ Buttner, R., Sr. Engineer
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Chabot, P., Superintendent, Technical Support
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Collins, S., Principal Engineer
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Cruse, C., Plant General Manager
+ DeAtley, R., Sr. Engineer
+ Denton, D., Shift Supervisor - Operations
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Detter, G., Director, Nuclear Regulatory Matters
- + Dickerson, J., Plant Engineer
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+ Eizenberg, Z., Mechanical Engineer - NES
+ Holston, B., Supervisor, Plant Design Support
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+ Hunter, G., Engineering Analysist - Maintenance
+ Ihnacik, J., Sr. Engineer
- + Katz, P., Manager, Nuclear Engineering Department Kemper, B., Principal Engineer
+ McHale, J., System Engineering
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- + McVicker, J., Principal Engineer, Nuclear Engineering Design i
+ Mrowca, B., Principal Engineer, Reliability Engineering l
+ Nolan, C., Mechanical Engineer - NES
- + Pavis, G., Director, Strategic Engineering
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+ Polak, M., Principal Engineer, Primary System Engineering
+ Rummel, B., System Engineering, Functional Test Coordination
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- + Sebra, K., Engineering Consultant, Nuclear Engineering Design
- + Volkoff, J., Compliance Engineer
Wasket, R., General Supervisor Design
- + Wilson, E., Compliance Engineer
Wood, J., Quality Audits
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U.S. Nuclear Reculatory Commission (USNRC)
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- + Flanders, S., Reactor Engineer - Intern
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Wilson, P., Senior Resident Inspector
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+ Those attending entrance meeting on February 1,1993
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Those attending exit meeting on February 5,1993
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