PNO-V-93-009, on 930314,operators at Facility Observed Decreasing Pressurizer Level & Pressure Due to Leak in SG-2. Operators Initiated Cooldown & Depressurization of RCS Using Steam Bypass Control Valves.Nrc Resident Inspector Onsite
| ML20034H750 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 03/14/1993 |
| From: | Johnson P, Sloan J, Wong H NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | |
| References | |
| PNO-V-93-009, PNO-V-93-9, NUDOCS 9303220017 | |
| Download: ML20034H750 (2) | |
=
/
.. March 14, 1993 PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE PNO-V-93-009 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 V staff on this date.
Facility Licensee Emeroency Classification Arizona Public Service Co.
Notification of Unusual Event Palo Verde 2 X Alert Wintersburg, Arizona Site Area Emergency
. Dockets: 50-529 General Emergency Not Applicable
Subject:
STEAM GENERATOR TUBE LEAK AND MANUAL REACTOR TR P (PALO VERDE 2)
At 4:25 a.m. (all times MST) on March 14, 1993, operators at Palo Verde Unit 2 observed decreasing pressurizer level and pressure. Additional charging flow was initiated. At 4:48 a.m., in response to continuing decreases in pressurizer pressure and level, operators manually tripped the reactor. A safety injection actuation signal (SIAS) and a contain-1 ment isolation actuation signal (CIAS) initiated automatically at 4:58 a.m.
An alert alarm was received on steam generator No. 2 (SG-2) blow-down radiation monitor RU-5, followed by an alarm on the condenser offgas monitor, RU-141. This and the lower auxiliary feedwater (AFW) flow needed to maintain level in SG-2 (compared to SG-1) indicated a leak in SG-2.
The licensee declared an alert at 5:02 a.m. and initiated actions as prescribed by emergency operating procedures (EOPs).
Pressurizer level and pressure reached minimum readings of 4% and 1670 psig, respectively. As of about 5:35 a.m., pressurizer level and pressure had been stabilized at 'about 8% and 1900 psig using all three charging pumps (44 gpm each). Two reactor coolant pumps (RCPs) were maintained in operation. At 6:05 a.m., the operators initiated cooldown and depressurization of the reactor coolant system (RCS) using the steam i
bypass control valves (SBPCVs) to the main condenser and the pressurizer spray valves, with steam generator levels maintained by an AFW pump.
Shortly thereafter, at an RCS pressure of about 1850 psig, the high pressure safety injection (HPSI) system began to inject, and pressurizer level was restored to about 40%. SG-2wasisolated(mainsteamand feedwater isolation valves closed) at 7:30 a.m.
As of 8:00 a.m., RCS
-pressure and temperature had been reduced to 1160 psig and 496 degrees F, respectively.
Pressurizer level was being maintained at about 50% using the three charging pumps, plus about 50 gpm flow from one HPSI pump (an apparent leak rate of approximately 150 gpm).
The licensee activated the Emer Technical Response Center (TSC)gency Operations Facility (E0F) and at 6:42 and 6:52 a.m., respectively.
Region V and NRC Headquarters entered the STANDBY mode at about 5:45 a.m., cnd the Region V Incident Response Center (IRC) was activated at 6:12 a.m. (5 12 a m PST The licensee has also activated its Joint PDR I&E PNG-V-93-OO9 FDR Mk
m
,=
~
3' 7 ~
t w.
- PN0-V-93-009 f.;
~
' n.? Emergency News Center (JENC).
CRCS gross: activity' before the event was.1;2 microcuries/ gram (uc/ gram),-
!withla' doseiequivalent-iodine of 0:019 uc/ gram. ?The steam; generator?.
l blowdown: radiation monitors detected activity and subsequently went: full
,(scale. The release pathway,Lvia = the steam jet air ejectors,Lis filtered
~ Tand monitored. The activity. released'is'a-fraction of. the : Technical:
-Specification limits. The licensee deployed two field monitoring' teams.
10ne team. detected low levels of activity.(approximately 200 cpm on a.
,: frisker) within the. site boundary. : No activity has been detected'
'offsite, and the licensee has projected a' site: boundary dose of!1ess than M 0.02 mrem in a.two-hour period, whichiis less than'1% of the-EPA:
Protective-Action Guidelines. Winds'are blowing in the direction.of the d
~
,5 normal site access, which has been closed. No action.has been-taken to si
' elimit traffic on Wintersburg Road adjacent to ~ th'e site..
-Stat'e and local officials:have been notified. The State of Arizona is d
9 sending a radiation monitoring. team to the. site.
1 r
1; The licensee has'made a press' release. The NRC resident inspector lis
- ]
consite.
.i
>This'information is current as of 8:30 a.m. MST on March :14,1993.
1
?
- d
Contact:
J. Sloan H. Wong P... Johnson (602)386-3638 (510)975-0296 (510)975-0300' d
ady
- Jt
. -n -
,y i
f;)
=l s
J
!m
]
0
.h mm l
i
- M N
h j
f'
-