View source for PNO-II-87-075, on 871021 & 25,voiding Noted in Vessel Head Regions.Caused by Mispositioned Manual Valve in Nitrogen Vent Line.Investigation Continuing

{{Adams
| number = ML20236M543
| issue date = 10/28/1987
| title = PNO-II-87-075:on 871021 & 25,voiding Noted in Vessel Head Regions.Caused by Mispositioned Manual Valve in Nitrogen Vent Line.Investigation Continuing
| author name = Scott M
| author affiliation = NRC OFFICE OF INSPECTION &amp; ENFORCEMENT (IE REGION II)
| addressee name = 
| addressee affiliation = 
| docket = 05000251
| license number = 
| contact person = 
| document report number = PNO-II-87-075, PNO-II-87-75, NUDOCS 8711130170
| document type = PRELIMINARY NOTIFICATION OF EVENT OR OCCURRENCE (PNO,, TEXT-INSPECTION &amp; AUDIT &amp; I&amp;E CIRCULARS
| page count = 1
}}
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October 28, 1987 PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE PN0-II-87-75 This preliminary notification constitutes EARLY notice of events of POSSIBLE safety or public interest significance. The information is as initially received without verifi-cation or' evaluation, and is basically all that is known by the Region II staff on this date.
FACILITY: Florida Power & Light Company            Licensee Emergency Classification:       !
Turkey Point Unit 4                         Notification of Unusual Event Docket No. 50-251                           Alert Homestead, Florida                          Site Area Emergency General Emergency X  Not Applicable

==SUBJECT:==
REACTOR VESSEL HEAD VOIDING With the reactor in cold shutdown on October 21, the plant noted voiding indications in the vessel head region. This was attributed to hydrogen coming out of solution. The plant was vented ard continued routine Mode 5 maintenance activities.
l    On October 25 at 1:55 a.m. (EDT), ar;other vessel head void appeared while the licensee was !
in the process of draining down the RCS for maintenance work. The void was indicated by     !
the Safety Parameter Display System (Reactor Vessel Level Indicating System) and was confirmed by a corresponding increase in pressurizer level.
After venting the vessu via the head vent system, and resuming draindown operatOns, a void reformed approximately three hours later. An Event Response Team was formed and their I    preliminary findings indicated a leaking motor operated isolation valve on the "4C "
Accumulator. Another void was formed later on October 25 while the pressurizer level was being lowered.
The 4C accumulator has been depressurized and verified to be empty.
A similar occurrence took place at the Davis- Besse Plant in which nitrogen leaking from a core flood tank in September 1987 accumulated in the the Decay Heat Removal System.
FP&L is aware of this occurrence and has taken measures to ensure their Residual Heat Removal System has not been affected.
During the venting of the 4C Accumulator, the licensee discovered a manual valve in the      i nitrogen vent line to be mispositioned. This is presently under investigation by the licensee.
The Resident Inspector was notified by the licensee following the first occurrence on October 21 and a regional inspector, as part of the NRC's augmented on-shift coverage, observed the second occurrence on October 25.
The resident inspectors are following up.
The State of Florida is being informed.
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This information is current as of 8:00 p.m. (EST) on October 26.                             1 l

==Contact:==
M. Scott - 242-0429                                                    ,'
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