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Event Notification Report for February 23, 1999

                    U.S. Nuclear Regulatory Commission
                              Operations Center

                              Event Reports For
                           02/22/1999 - 02/23/1999

                              ** EVENT NUMBERS **

35390  35392  35393  

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|Power Reactor                                    |Event Number:   35390       |
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| FACILITY: SEABROOK                 REGION:  1  |NOTIFICATION DATE: 02/21/1999|
|    UNIT:  [1] [] []                 STATE:  NH |NOTIFICATION TIME: 11:28[EST]|
|   RXTYPE: [1] W-4-LP                           |EVENT DATE:        02/20/1999|
+------------------------------------------------+EVENT TIME:        21:00[EST]|
| NRC NOTIFIED BY:  STEVE MORRISSEY              |LAST UPDATE DATE:  02/22/1999|
|  HQ OPS OFFICER:  JOHN MacKINNON               +-----------------------------+
+------------------------------------------------+PERSON          ORGANIZATION |
|EMERGENCY CLASS:          N/A                   |JIM TRAPP            R1      |
|10 CFR SECTION:                                 |                             |
|NLTR                     LICENSEE 24 HR REPORT  |                             |
|                                                |                             |
|                                                |                             |
|                                                |                             |
+-----+----------+-------+--------+-----------------+--------+-----------------+
|UNIT |SCRAM CODE|RX CRIT|INIT PWR|   INIT RX MODE  |CURR PWR|  CURR RX MODE   |
+-----+----------+-------+--------+-----------------+--------+-----------------+
|1     N          Y       100      Power Operation  |100      Power Operation  |
|                                                   |                          |
|                                                   |                          |
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                                   EVENT TEXT                                   
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| ELEVEN DEAD SEA DUCKS FOUND IN CIRCULATING WATER SCREEN WASH DEBRIS          |
|                                                                              |
| Eleven dead sea ducks were observed in Seabrook station's circulating water  |
| screen wash debris on February 20, 1999 at approximately 2100 hours.  It is  |
| not known at this time whether the ducks were alive or dead upon entering    |
| the offshore intake structure.  Sea ducks are diving birds which feed        |
| underwater.  This is a 24 hour notification in accordance with section 4.1   |
| of the environmental protection plan, appendix B of the operating license.   |
|                                                                              |
| The NRC resident inspector was notified of this event report by the          |
| licensee.                                                                    |
|                                                                              |
| * * * UPDATE AT 1407 EST ON 2/22/99 BY STEVE MORRISSEY TO FANGIE JONES * *   |
| *                                                                            |
|                                                                              |
| Two additional dead sea ducks were observed in Seabrook station's            |
| circulating water screen wash debris on February 21, 1999 at approximately   |
| 2245 hours.  The licensee believes these additional dead sea ducks are part  |
| of the original group and were not picked up on the screen wash of the night |
| of February 20, 1999.                                                        |
|                                                                              |
| The licensee notified the NRC Resident Inspector.  The Operations Officer    |
| notified the R1DO (Richard Barkley).                                         |
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|Power Reactor                                    |Event Number:   35392       |
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| FACILITY: GINNA                    REGION:  1  |NOTIFICATION DATE: 02/22/1999|
|    UNIT:  [1] [] []                 STATE:  NY |NOTIFICATION TIME: 16:27[EST]|
|   RXTYPE: [1] W-2-LP                           |EVENT DATE:        02/22/1999|
+------------------------------------------------+EVENT TIME:        15:40[EST]|
| NRC NOTIFIED BY:  ROY GILLOW                   |LAST UPDATE DATE:  02/22/1999|
|  HQ OPS OFFICER:  FANGIE JONES                 +-----------------------------+
+------------------------------------------------+PERSON          ORGANIZATION |
|EMERGENCY CLASS:          N/A                   |RICHARD BARKLEY      R1      |
|10 CFR SECTION:                                 |                             |
|AOUT 50.72(b)(1)(ii)(B)  OUTSIDE DESIGN BASIS   |                             |
|                                                |                             |
|                                                |                             |
|                                                |                             |
+-----+----------+-------+--------+-----------------+--------+-----------------+
|UNIT |SCRAM CODE|RX CRIT|INIT PWR|   INIT RX MODE  |CURR PWR|  CURR RX MODE   |
+-----+----------+-------+--------+-----------------+--------+-----------------+
|1     N          Y       75       Power Operation  |75       Power Operation  |
|                                                   |                          |
|                                                   |                          |
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                                   EVENT TEXT                                   
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| DISCOVERY OF MODELING ERRORS IN THE MAIN STEAM LINE BREAK ANALYSIS           |
|                                                                              |
| The following text is a portion of a facsimile received from the licensee:   |
|                                                                              |
| "Ginna Station was notified by its NSSS vendor, Westinghouse Electric        |
| Company, of two modeling errors in the analysis for a main steam line break  |
| (MSLB) with an assumed single failure of a feed water control valve.  The    |
| first error was not taking into account the full amount of energy released   |
| to containment by the flashing of high temperature feed water downstream of  |
| the motor operated isolation valves after feed water flow is isolated.  The  |
| second error was a mistake in the assumed time of feed water isolation.      |
| Isolation should have occurred at 85 seconds but incorrectly occurred at 15  |
| seconds.                                                                     |
|                                                                              |
| "Preliminary analyses show that in the past, under the postulated conditions |
| of a MSLB coincident with a feed water regulating valve failure, the         |
| containment pressure design limit may have been exceeded and that Ginna      |
| Station may have been in a condition outside the design basis of the plant.  |
| This condition is also being evaluated for the criteria of l0CFR2l.          |
| However, a recently performed analysis for the current operating cycle using |
| more realistic modeling assumptions, accounting for cycle specific shutdown  |
| margin values and crediting current heat sink temperatures showed that       |
| acceptable results (less than 60 psig) were obtained.  Thus there is no      |
| concern for continued plant operation through the end of the current cycle   |
| (March 1, 1999) based on these results."                                     |
|                                                                              |
| Further analyses will be performed prior to the plant restarting after the   |
| next refueling.                                                              |
|                                                                              |
| The licensee notified the NRC Resident Inspector.                            |
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+------------------------------------------------------------------------------+
|Power Reactor                                    |Event Number:   35393       |
+------------------------------------------------------------------------------+
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| FACILITY: DUANE ARNOLD             REGION:  3  |NOTIFICATION DATE: 02/22/1999|
|    UNIT:  [1] [] []                 STATE:  IA |NOTIFICATION TIME: 22:12[EST]|
|   RXTYPE: [1] GE-4                             |EVENT DATE:        02/22/1999|
+------------------------------------------------+EVENT TIME:        20:45[CST]|
| NRC NOTIFIED BY:  KEVIN STEIMER                |LAST UPDATE DATE:  02/22/1999|
|  HQ OPS OFFICER:  FANGIE JONES                 +-----------------------------+
+------------------------------------------------+PERSON          ORGANIZATION |
|EMERGENCY CLASS:          N/A                   |BRUCE JORGENSEN      R3      |
|10 CFR SECTION:                                 |                             |
|AINC 50.72(b)(2)(iii)(C) POT UNCNTRL RAD REL    |                             |
|                                                |                             |
|                                                |                             |
|                                                |                             |
+-----+----------+-------+--------+-----------------+--------+-----------------+
|UNIT |SCRAM CODE|RX CRIT|INIT PWR|   INIT RX MODE  |CURR PWR|  CURR RX MODE   |
+-----+----------+-------+--------+-----------------+--------+-----------------+
|1     N          Y       100      Power Operation  |100      Power Operation  |
|                                                   |                          |
|                                                   |                          |
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                                   EVENT TEXT                                   
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| BOTH STANDBY GAS TREATMENT SYSTEMS MOMENTARILY INOPERABLE                    |
|                                                                              |
| The following text is a portion of a facsimile received from the licensee:   |
|                                                                              |
| "The 'B' Standby Gas Treatment (SBGT) subsystem was undergoing its 10-hour   |
| monthly surveillance testing when it was discovered that the flow indicating |
| controller for the 'A' train was not properly displaying flow.  The 'A' SBGT |
| subsystem was declared inoperable at 1113 on 2/22/99 while monthly           |
| surveillance testing continued on the 'B' SBGT subsystem.  Repairs were      |
| completed on the 'A' flow indicating controller coincident with the ongoing  |
| surveillance test on the 'B' SBGT subsystem.                                 |
|                                                                              |
| "In accordance with the monthly surveillance for shutting down a 'B' SBGT    |
| subsystem, its mode selector switch was momentarily placed in the  manual    |
| position at 2045 hours for approximately 15 seconds, which in effect         |
| disabled 'B' SBGT from automatically starting and it was therefore declared  |
| inoperable.  For those 15 seconds, both SBGT subsystems were considered      |
| inoperable which is a condition that could prevent the fulfillment of the    |
| safety function of SBGT system to control the release of radioactive         |
| material.  This is considered a 4-hour reportable event per                  |
| 50.72(b)(2)(iii)(C).                                                         |
|                                                                              |
| "The 'B' SBGT subsystem was restored to operable status once the mode        |
| selector switch was returned to the  auto position.  Surveillance testing is |
| currently in progress on the 'A' SBGT subsystem to demonstrate operability   |
| for the repairs made to its flow indicating controller."                     |
|                                                                              |
| The licensee notified the NRC Resident Inspector.                            |
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