United States Nuclear Regulatory Commission - Protecting People and the Environment

Morning Report for June 6, 2000

                       Headquarters Daily Report

                         JUNE 06, 2000

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                    REPORT             NEGATIVE            NO INPUT
                    ATTACHED           INPUT RECEIVED      RECEIVED

HEADQUARTERS        X
REGION I                               X
REGION II                              X
REGION III                             X
REGION IV                              X
PRIORITY ATTENTION REQUIRED  MORNING REPORT - HEADQUARTERS JUNE  6, 2000

Licensee/Facility:                     Notification:

Carolina Power & Light Co.             MR Number: H-00-0034
Brunswick 1                            Date: 06/06/00
Southport,North Carolina
Dockets: 50-325
BWR/GE-4

Subject: Potential for Chemical Fire Suppressant Release to Impact
         Operability of Emergency Diesel Generators

Reportable Event Number: 36750

Discussion:

On 3/3/00, Carolina Power & Light, the Brunswick licensee, declared an
Unusual Event (UE) because of a loss of offsite power (LOOP) to both
4160-volt emergency electrical buses at Brunswick Unit 1 (EN #36750).
Unit 1 was in a refueling outage with relay testing ongoing in the plant
switchyard, when a switch positioning error resulted in a LOOP.  All four
emergency diesel generators (EDGs) started as designed, with DG1 and DG2
supplying their respective safety-related buses.  DG3 and DG4 did not
pick up loads to their respective buses because those buses did not lose
power.

About two hours after the LOOP, DG2 tripped and the diesel building fire
protection system actuated when the excitation system power potential
transformer (PPT) for DG2 shorted out.  A chemical fire suppressant
(Halon 1301) was released into the basement of the diesel building where
the PPT was located.  The halon discharge into the basement created
sufficient pressure to unexpectedly open a tornado damper between the
basement and the rest of the building.  Halon escaped into the upper
portion of the building, where DG1, DG3, and DG4 drew in an air/halon
mixture through their individual air intakes.

The release of halon into the upper portion of the diesel generator
building raised two concerns regarding EDG operability.  The halon and
combustion interaction caused the lube oil on the three running EDGs to
become contaminated with halon in excess of the oil vendor-approved limit
of 50 parts per million (ppm).  During the combustion process it is
normal for some of the combustion chamber exhaust gases to interact with
the crankcase oil because of leakage of the gases past the piston rings.
The concern with halon contaminating the oil is an accelerated
degradation of the oil and increased corrosion rates.  The halon reduces
the alkalinity of the oil which may increase the formation of acids that
could cause corrosion of the engine components.  Oil samples taken from
DG3 and DG4 indicated halon levels of 53 ppm.  Oil samples from DG1
indicated halon levels of 200 ppm.  The licensee determined that halon
contamination of the oil was not an immediate operability concern, but it
could result in premature degradation of engine components.  The licensee
has set 20 ppm as an administrative limit for halon in the lube oil.  The
licensee will change the oil in each EDG during the next scheduled outage
window.

The second concern with EDG operability is the effect of the air/halon
mixture on the ability of the EDGs to operate at maximum load capacity.
Subsequent to the event, the licensee performed testing to determine if
the air/halon mixture would affect the EDGs.  The licensee conservatively

HEADQUARTERS      MORNING REPORT     PAGE  2          JUNE  6, 2000
MR Number: H-00-0034 (cont.)

assumed that the full 6 percent halon atmosphere released into the
basement would be ingested by one of the three operating EDGs.  The
licensee concluded that there was more than adequate margin in the volume
of available combustion air and the release of the halon would have no
effect on EDG operability.

Contact:  Eugene Guthrie, RII        (910)457-9531
          David Skeen, NRR           (301)415-1174
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