ML20059J026
| ML20059J026 | |
| Person / Time | |
|---|---|
| Site: | Limerick  |
| Issue date: | 01/24/1994 |
| From: | Rinaldi F Office of Nuclear Reactor Regulation |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 9401310296 | |
| Download: ML20059J026 (7) | |
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UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON. D.C. 20555-0001
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January 24. 1994 Docket Nos. 50-352 and 50-353 LICENSEE:
PECO Energy Company FACILITY:
Limerick Generating Station, Units 1 and 2
SUBJECT:
SUMMARY
OF DECEMBER 14, 1993, MEETING REGARDING THE RISK OF PERFORMING 24-H0VR EMERGENCY DIESEL GENERATOR TESTING AT POWER On December 14, 1993, representatives of PECO Energy Company met with the NRC staff to discuss the risk of performing 24-hour emergency diesel generator testing at power. Meeting attendees are listed in Enclosure 1.
During the evaluation of the 24-Month Fuel Cycle Technical Specifications (TS)
Amendment for the Limerick Generating Station (LGS), the staff became aware that 24-hour EDG testing was being performed with the units at power.
The staff expressed concern regarding this practice since the occurrence of a single event / electrical disturbance while the electrical output of an EDG is in parallel with the offsite power system could potentially result in the simultaneous loss of power from both of these sources when one of them is needed to power emergency loaos.
In response to this concern, the licentee provided information suggesting that the electrical design incorporates features to disconnect the two power sources should such a disturbance occur.
However, the staff continued to express concern regarding electrically isolating the offsite system from the electrical output of an EDG should the need occur.
The subject meeting was scheduled to further discuss and resolve the staff's concern.
The LGS onsite emergency electrical power system design for each unit consists of 4 dedicated EDGs and 4 separate 4 kV safeguard bus load groups.
For each unit, the electrical design arrangement is such that each of the 4 EDGs provides power to only one of the four 4kV safeguards bus load groups (Enclosure 2).
During the subject meeting, the licensee presented information indicating why performing 24-hour EDG testing at power has low safety significance. The licensee also indicated that prior to conducting 24-hour EDG testing, an overhaul on each EDG is performed. This overhaul is followed by unloaded and loaded break-in testing runs.
Further, the licensee provided information indicating why 2 of 4 EDGs supply adequate power to mitigate the consequences of a Design Basis Accident (DBA), with few exceptions.
The exceptions involve three two train systems that are supplied power by EDG 11 and EDG 12. These two EDGs are arranged to supply power to two Unit 1 4kV safeguards bus load groups.
The three 2-train systems are the Standby Gas Treatment System, the Reactor Enclosure Recirculation System, and the Control Room Ventilation System.
9401310296 940124 PDR ADOCK 05000352
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. Based on information provided by the licensee during the meeting, the staff concluded that 2 of 4 EDG supplied electrical divisions provide sufficient power to mitigate the consequences of a DBA excluding the exceptions noted.
The requirements addressing the noted exceptions are provided in TS Section 3/4.6.5.3, " Containment Systems - Standby Gas Treatment System - Common System," TS Section 3/4.7.2, " Plant System - Control Room Emergency Fresh Air Supply System - Common System," and TS Section 3/4.6.5.4 " Containment System -
Reactor Enclosure Recirculation System.
l These TS Sections require that if one train of the applicable system is inoperable, the licensee must enter a 7-day action statement. However, if the EDG associated with a train is inoperable, the licensee must enter a special EDG action statement. The special EDG action statement requires restoration of the inoperable EDG to operability within 3 days if the EDG that powers the redundant train is inoperable or if the redundant train is otherwise inoperable.
Further, if two trains are inoperable, the licensee must enter a TS 3.0.3, which requires initiating within one hour, actions leading to unit shutdown.
In addition, during the 24-hour EDG testing, if an emergency signal is generated then that signal should result in the applicable EDG emergency output breaker opening and if needed EDG loading in accordance with the DBA loading sequence.
Our discussions with the licensee indicated that although PECO is requesting a change from an 18-month to 24-month interval for 24-hour EDG testing, they do-not plan to alter the frequency of the current EDG maintenance overhauls and/or the break-in testing.
Therefore, in effect, there are currently no changes from the current practice requiring performing these actions for these items.
During the meeting, the staff raised two additional questions. One question requested the licensee to identify if the EDGs have ever been tested or analyzed for the situation where an EDG output breaker is opened while supplying 110% of its continuous rating. The second question requested confirmation that the residual heat removal (RHR) valve can be operated, remotely, or manually to establish a flow path for long-term cooling. The licensee agreed to provide the answers to the above questions during a follow-up phone call.
On January 4,1994, the licensee provided to the staff their reply to the two staff questions. The licensee stated that a spare EDG was tested-by PEC0 and Colt, the equipment manufacturer. The EDG was observed to reject a 110% load and that the overspeed trip setpoint was not reached. Also, significant margins to reach the overspeed trip setpoint were observed during the test.
Further, the licensee confirmed that the RHR valve cannot be accessed in a post accident situation.
However, when an EDG, which powers either of the RHR loops used for long-term cooling is inoperable, the special EDG action statement noted above is entered.
II The licensee is committed to incorporate in the next update to the LGS's Updated Final Safety Analysis Report (UFSAR), scheduled for November 1994, information that would document and explain why only 2 out of 4 EDGs provide sufficient power to mitigate the consequences of a DBA, including a discussion for the exceptions identified above.
Further, the licensee committed to provide, in the near 'uture, documentation' identifying the plant status during the surveillance testing identified by TS 4.8.1.1.1.b and TS 4.8.1.1.2.e.
Based on the information provided by the licensee at the meeting and in the subsequent telephone conference call, the Electrical Engineering Branch staff
.; to complete a safety evaluation addressing the 24-Month Fuel Cycle TS amendment.
/S/
Frank Rinaldi, Project Manager Project Directorate I-2 Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation
Enclosures:
1.
Meeting Attendees 2.
Licensee Handout cc w/ enclosures:
See next page DISTRIBUTION w/ enclosure 1 DISTRIBUTION w/ enclosures 1-and 2 TMurley/FMiraglia LNicholson Docket File LCallan VMcCree NRC & Local PDRs SVarga ACRS(10)
PDI-2 Reading JCalvo FRinaldi CMiller EWenzinger, RGN-I M0'Brien JWhite, RGN-I OGC EJordan DNguyen FAshe CBerlinger EWeiss TEaslick 0FFICE PDI/$fI M [ PDI-2/PM V /n EELB [ b PDI-2/D s il- -
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a The licensee is committed to incorporate in the next update to the LGS's-Updated Final Safety Analysis Report (UFSAR), scheduled for November 1994, information that would document and explain why only 2 out of 4 EDGs provide sufficient power to mitigate the consequences of a DBA, including a discussion for the exceptions identified above.
Further, the licensee committed to provide, in the near future, documentation identifying the plant status during the surveillance testing identified by TS 4.8.1.1.1.b and TS 4.8.1.1.2.e.
Based on the information provided by the licensee at the meeting and in the subsequent telephone conference call, the Electrical Engineering Branch staff is to complete a safety evaluation addressing the 24-Month Fuel Cycle TS amendment.
/S/
Frank Rinaldi, Project Manager Project Directorate I-2 Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation
Enclosures:
1.
Meeting Attendees 2.
Licensee Handout cc w/ enclosures:
See next page DISTRIBUTION w/ enclosure 1 DISTRIBUTION w/ enclosures 1 and 2 TMurley/FMi raglia LNicholson Docket File LCallan VMcCree NRC & Local PDRs SVarga ACRS(10)
PDI-2 Reading JCalvo FRinaldi CMiller EWenzinger, RGN-I M0'Brien JWhite, RGN-I OGC EJordan DNguyen FAshe CBerlinger EWeiss-TEaslick OFFICE
- D1/i/ dj, PDI-2/PM, W EELB[ b PDI-2/D J
NAME M0$Nr'idnb' FRina(d k b CBerlinger Chiller b Y DATE
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~6FFICIAL RECORD COPY DOCUMENT NAME:
LIl2-14.MTS
PECO Energy Company Limerick Generating Station, Units 1 & 2 cc:
J. W. Durham, Sr., Esquire Mr. William P. Dornsife, Director Sr. V.P. & General Counsel Bureau of Radiation Protection PECO Energy Company PA Dept. of Environmental Resources 2301 Market Street P. O. Box 2063 Philadelphia, Pennsylvania 19101 Harrisburg, Pennsylvania 17120 Mr. Rod Krich 52A-5 Mr. James'A. Muntz PECO Energy Company Superintendent-Technical 955 Chesterbrook Boulevard Limerick Generating Station Wayne, Pennsylvania 19087-5691 P. O. Box A Sanatoga, Pennsylvania 19464 Mr. David R. Helwig, Vice President Limerick Generating Station Mr. Gil J. Madsen Post Office Box A Regulatory Engineer Sanatoga, Pennsylvania 19464 Limerick Generating Station P. O. Box A Mr. Robert Boyle Sanatoga, Pennsylvania 19464 Plant Manager Limerick Generating Station Library P.O. Box A US Nuclear Regulatory Commission Sanatoga, Pennsylvania 19464 Region I 475 Allendale Road Regional Administrator King of Prussia, PA 19406 U.S. Nuclear Regulatory Commission Region I Mr. Larry Hopkins 475 Allendale Road Superintendent-0perations King of Prussia, PA 19406 Limerick Generating Station P. O. Box A Mr. Thomas Kenny Sanatoga, Pennsylvania 19464 Senior Resident Inspector US Nuclear Regulatory Commission Mr. George A. Hunger, Jr.
P. O. Box 596 Director-Licensing, MC 52A-5 Pottstown, Pennsylvania 19464 PECO Energy Company Nuclear Group Headquarters Mr. Richard W. Dubiel Correspondence Control Desk Superintendent - Services P.O. Box 195 Limerick Generating Station Wayne, Pennsylvania 19087-0195 P.O. Box A Sanatoga, Pennsylvania 19464 John Doering, Chairman Nuclear Review Board PECO Energy Company 955 Chesterbrook Boulevard Mail Code 63C-5 Wayne, Pennsylvania 19087 1
a ENCLOSURE 1 MEETING ATTENDEES LIST 24-H0VR TESTING OF EMERGENCY DIESEL GENERATORS DECEMBER 14. 1993 NAME ORGANIZATION F. Rinaldi NRC/NRR L. Nicholson NRC/NRR D. Nguyen NRC/NRR' F. Ashe NRC/NRR C. Berlinger NRC/NRR E. Weiss NRC/NRR T. Easlick NRC/RGN-1 (Resident Inspector)
R. Krich PECo W. Mindick PECo-J. Ottaviano PEco W. Lewis PECo V. Warren PEco 4
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