Information Notice 2000-09, Steam Generator Tube Failure at Indian Point Unit 2
| ML011930011 | |
| Person / Time | |
|---|---|
| Site: | Indian Point  |
| Issue date: | 06/28/2000 |
| From: | Marsh L Operational Experience and Non-Power Reactors Branch |
| To: | |
| References | |
| FOIA/PA-2001-0256 IN-00-009 | |
| Download: ML011930011 (5) | |
cc: Holody
Urban
UNITED STATES
Nick
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, D.C. 20555-0001 June 28, 2000
NRC INFORMATION NOTICE 2000-09: STEAM GENERATOR TUBE FAILURE AT INDIAN
POINT UNIT 2
Addressees
All holders of operating licenses for nuclear power reactors except those who have ceased
operations and have certified that fuel has been permanently removed from the reactor vessel.
Purpose
The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice to inform
addressees of a steam generator tube failure at Indian Point Unit 2. NRC investigations of the
licensee's steam generator inspection program are ongoing and any potentially generic issues
identified will be communicated in a separate generic communication. However, the
investigations to date re-emphasize the importance of licensee involvement with ongoing
industry efforts to understand and detect steam generator degradation. It is expected that
recipients will review the information for applicability to their facilities and consider actions, as
appropriate, to avoid similar problems. However, suggestions contained in this information
notice are not NRC requirements; therefore, no specific action or written response is required.
Description of Circumstances
On February 15, 2000, at 7:17 p.m., the Indian Point Unit 2 nuclear plant experienced a steam
generator tube failure,, which required the declaration of an Alert at 7:29 p.m., and a manual reactor trip at 7:30 p.m. The operators identified that the #24 steam generator was the source
of the leak and completed isolation of the #24 steam generator by 8:31 p.m.
At 9:02 p.m., the operator opened the high-pressure steam dump valves and established an
excessive primary plant cooldown rate that caused a rapid reduction in the pressurizer level and
required the operators to manually initiate safety injection. The operators reset the safety
injection at 9:21 p.m., reduced the reactor coolant system pressure to about 970 psig at 9:32 p.m., and re-commenced a plant cooldown at 11:35 p.m.
The residual heat removal (RHR) system was placed in service on February 16, 2000, at 12:38 p.m., and primary plant pressure was reduced below the #24 steam generator pressure to
terminate the steam generator tube leakage at 2:20 p.m. The plant cooldown continued, and
the plant entered cold shutdown at 4:57 p.m. The licensee exited the Alert at 6:50 p.m.
The NRC sent an Augmented Inspection Team (AIT) on February 18, 2000, to review the
causes, safety implications, and licensee actions associated with the event. The AIT developed
a sequence of events, determined the risk significance of the event, and assessed the response
by the plant staff and management. The cause of the tube failure was outside the scope of this
inspection and is currently being reviewed separately by the NRC. The AIT's report is
presented in Inspection Report 05000247/2000-02, dated April 28, 2000 (Accession Number
Discussion
The event was risk significant. It involved a steam generator tube failure that resulted in an
initial primary-to-secondary leak of reactor coolant of approximately 146 gallons per minute and
required an "Alert" declaration (the second level of emergency action in the NRC-required
emergency response plan). The event resulted in a minor radiological release to the
environment that was well within regulatory limits. No radioactivity was measured offsite above
normal background levels, and the event did not adversely impact the public health and safety.
The licensee performed the necessary actions to protect the health and safety of the public.
Specifically, the operators promptly and appropriately took those actions in the emergency
operating procedures to trip the reactor, isolate the affected steam generator, and depressurize
the reactor coolant system. Additionally, the necessary event mitigation systems worked
properly. Notwithstanding the above actions, the AIT identified performance problems in
several broad areas that challenged operators, complicated the event response, delayed
achieving the cold shutdown condition, and affected the radiological release. The problems
involved operator performance, procedure quality, equipment performance, technical support, and emergency response.
Operator Performance
Some operator performance problems were noted during the plant cooldown phase involving
the following:
While attempting to cool down the reactor coolant system (RCS), the reactor operator
initiated an excessive cooldown rate that exceeded procedural and Technical
Specification limits. The excessive cooldown led to several conditions that complicated
the subsequent event response and delayed the RCS cooldown.
Operators were slow to recognize configuration lineup problems that (1) prevented
successful operation of the auxiliary spray system to lower RCS pressure and
(2) delayed heatup of the RHR system.
Procedure Quality
The procedures adequately guided the initial operator response; however, several procedure
problems were identified that delayed the cooldown and depressurizing of the RCS. Procedure
deficiencies affected Standard Operating Procedures, Emergency Operating Procedures, and
Emergency Plan Implementing Procedures. Specific activities included initiation of RHR
cooling, initiation of component cooling water alignment, use of auxiliary pressurizer spray, use
of methods to monitor RCS temperature to maintain cold shutdown conditions, and initiation of emergency response organization (ERO) notifications. Station personnel were previously
aware of the procedure issue involving initiation of RHR cooling but had not corrected the
problem before this event.
Equipment Performance
The necessary event mitigation systems, including the reactor protection system, the auxiliary
feedwater system, and the safety injection system, functioned properly. However, several
longstanding equipment performance problems were identified that challenged operators during
this event:
Two losses of condenser vacuum resulted from problems with the operation of the
automatic steam supply pressure control valve to the steam jet air ejectors, and the #22 condenser vacuum pump.
The isolation valve seal water system became inoperable during the event and required
operator action and an entry into a Technical Specification Limiting Condition for
Operation Action Statement.
A containment entry was required to install a temporary nitrogen supply to the
pressurizer power-operated relief valve to compensate for a design deficiency. This
action was required before placing the overpressure protection system in service.
The steam generator leak rate monitoring equipment had been degraded for an
extended period, and limited the amount of steam generator leak rate information
available to the operators before the event.
The AIT determined that the number and duration of the equipment problems reflected
weaknesses in engineering, corrective action processes, and operational support at the station.
The licensee's response to a number of the equipment problems identified during the event
reflected an acceptance of "working around" the problem rather than fixing it.
Emergency Response
The ERO took the necessary steps to ensure the protection of public health and safety. The
operators properly classified the event, and the licensee implemented a thorough peer review of
the emergency response to this event. The AIT identified several emergency plan and
implementing procedure problems similar to those identified by the licensee's peer review team, including the following:
The emergency response staff was slow to activate the emergency facilities.
The licensee was slow to establish accountability (i.e., identify the location) of
emergency response personnel. The emergency response data system -(ERDS) was inoperable for the first several hours
of the event as a result of a pre-existing equipment problem.
Problems were noted in the implementation of the media response plan.
Problems were identified involving the timeliness and quality of technical support
provided to the operators.
The licensee developed and was in the process of implementing an emergency response
improvement plan before the event.
This information notice requires no specific action or written response. However, recipients are
reminded that they are required to consider industry-wide operating experience (including NRC
information notices) when practical when setting goals and performing periodic evaluations
under Section 50.65, "Requirements for monitoring the effectiveness of maintenance at nuclear
power plants," of Part 50 of Title 10 of the Code of Federal Regulations. If you have any
questions about the information in this notice, please contact the one of the technical contacts
listed below or the appropriate Office of Nuclear Reactor Regulation (NRR) project manager.
/Ledyard
B. Mars , Chief
Events Assessment, Generic Communications
and Non-Power Reactors Branch
Division of Regulatory Improvement Programs
Office of Nuclear Reactor Regulation
Technical contacts:
Lawrence Doerflein, Region I
301-415-1171
610-337-5378 E-mail: eibl0.nrc..qov
E-mail: ltdOnrc.gov
Peter Eselgroth, Region I
Raymond Lorson, Region I
610-337-5234
603-474-3589 E-mail: pwemnrc.aov
E-mail: rklO.nrc.aov
Attachment: List of Recently Issued NRC Information Notices
Attachment LIST OF RECENTLY ISSUED
NRC INFORMATION NOTICES
Information
Date of
Notice No.
Subject
Issuance
Issued to
2000-08 Inadequate Assessment of the
5/15/2000
All holders of operating licensees
Effect of Differential
Temperatures on Safety
Related Pumps
National Institute for
Occupational Safety and
Health Respirator User Notice:
Special Precaustions for Using
Certain Self-Contained
Breathing Apparatus Air
Cylinders
Offsite Power Voltage
Inadequacies
Recent Medical
Misadministrations Resulting
from Inattention to Detail
1999 Enforcement Sanctions
for Deliberate Violations of
NRC Employee Protection
Requirements
High-Efficiency Particulate Air
Filter Exceeds Mass Limit
Before Reaching Expected
Differential Pressure
Failure of Criticality Safety
Control to Prevent Uranium
Dioxide (U0 2) Powder
Accumulation
4/10/2000
3/22/2000
3/06/2000
2/25/2000
2/22/2000
2/22/2000
for nuclear power reactors
All holders of operating licenses
for nuclear power reactors,non
power reactors, and all fuel cycle
and materiallicensees required to
have an NRC-approved
All holders of operating licenses
for nuclear power reactors, except those who have
permanently ceased operations
and have certified that fuel has
been permanently removed from
the reactor
All medical licensees
All NRC licensees
All NRC licensed fuel-cycled
conversion, enrichment, and
fabrication facilities
All NRC licensed fuel-cycled
conversion, enrichment, and
fabrication facilities
OL = operating License
CP = Construction Permit
2000-07
2000-06
2000-05
2000-04
2000-03
2000-02