View source for PNO-I-86-028, on 860411,controlled Shutdown Initiated to Investigate Three Leaking Valves in LPCI Portion of RHR Sys. During Shutdown,Reactor Scrammed at Low Power When MSIVs Closed.Caused by Faulty Reactor Mode Switch

{{Adams
| number = ML20202J829
| issue date = 04/14/1986
| title = PNO-I-86-028:on 860411,controlled Shutdown Initiated to Investigate Three Leaking Valves in LPCI Portion of RHR Sys. During Shutdown,Reactor Scrammed at Low Power When MSIVs Closed.Caused by Faulty Reactor Mode Switch
| author name = Kister H, Strosnider J
| author affiliation = NRC OFFICE OF INSPECTION &amp; ENFORCEMENT (IE REGION I)
| addressee name = 
| addressee affiliation = 
| docket = 05000293
| license number = 
| contact person = 
| document report number = PNO-I-86-028-01, NUDOCS 8604160198
| 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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OCS No:    50293860411 Date: April 14, 1986 PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE--PNO-I-86-28 This preliminary notification constitutes EARLY notice of events of POSSIBLE safety or public interest significance. The information is as initially received without verification or evaluation, and is basically all that is known by the Region I staff on this date.
Facility: Boston Edison Co.                Licensee Emergency Classification:
Pilgrim Nuclear Power Station _X_ Notification of Unusual Event Plymouth, Massachusetts                                                           i Alert                                          '
CN 50-293                          Site Area Emergency                            ,
Gcr:eral Emergency                              1 Not Applicable

==Subject:==
NRC AUGMENTED INSPECTION TEAM At 4:53 p.m. on April 11, 1986, Pilgrim began a controlled shutdown to investigate three leaking valves (a check valve and two motor-operated injection valves) in the low pressure coolant injection (LPCI) portion of the residual heat removal system.
The RHR system had been periodically pressurized to about 400 psig during April 10 and 11, presumably by leakage of reactor coolant past these valves. The RHR system pressure is normally at 115 psig. An Unusual Event was declared at 4:53 p.m., due to the coolant leakage.
During the shutdown, the reactor scrammed at low power af ter the main steam line               !
isolation valves (MSIV) unexpectedly closed. The licensee believes that MSIV isolation          '
was caused by mechanical problems with the reactor mode switch. Following the scram, the. operators had difficulty re-opening the four outboard MSIV's. The reactor cooldown was controlled by drawing off steam with the high pressure coolant injection system (HPCI). This is a normal cooldown procedure if the MSIV's are closed. A similar MSIV             '
isolation and scram sequence occurred on April 4,1986 (see PNO-I-86-26). The reactor had been restarted on April 10, following a six-day outage.
An NRC Augmented Inspection Team (AIT) was dispatched to the site on April 12, 1986.
to investigate the leaking RHR valves and the anomalies that occurred during shutdown.
The team is. currently onsite and following the licensee's actions. The licensee has agreed to seek NRC concurrence prior to starting the reactor up from this outage.
The Commonwealth of Massachusetts has been notified.
CONTACT: Jack R. Strosnider                Harry B. Kister 488-1128                       488-1233 DISTRIBUTION:
H. St.                 MNBB       Phillips      E/W Chairman Palladino EDO                                        Willste _ Mail: ADM:DMB NRR            IE           NMSS               DOT:Trans only Comm. Zech             PA                       OIA           RES Comm. Bernthal         ELD                      AE00 Comm. Roberts Comm. Asselstine ACRS                   Air Rights                INPO M SECY CA SP                       NSACM' POR                    Regional Offices               TMI Resident Section ll: co RI Resident Office Q'9 Licensee:
8604160198 860414 PDR   I&E PNO-I-86-028        PDR                                                -   q[   l
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