Information Notice 2000-09, Steam Generator Tube Failure at Indian Point Unit 2

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

ML003710036).

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

IN2000-09 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.

IN2000-09 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: Eric Benner, NRR 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 for nuclear power reactors

Temperatures on Safety

Related Pumps

2000-07 National Institute for 4/10/2000 All holders of operating licenses

for nuclear power reactors,non

Occupational Safety and

power reactors, and all fuel cycle

Health Respirator User Notice:

and materiallicensees required to

Special Precaustions for Using

have an NRC-approved

Certain Self-Contained

emergency plan

Breathing Apparatus Air

Cylinders

3/22/2000 All holders of operating licenses

2000-06 Offsite Power Voltage

for nuclear power reactors, Inadequacies

except those who have

permanently ceased operations

and have certified that fuel has

been permanently removed from

the reactor

3/06/2000 All medical licensees

2000-05 Recent Medical

Misadministrations Resulting

from Inattention to Detail

1999 Enforcement Sanctions 2/25/2000 All NRC licensees

2000-04 for Deliberate Violations of

NRC Employee Protection

Requirements

High-Efficiency Particulate Air 2/22/2000 All NRC licensed fuel-cycled

2000-03 conversion, enrichment, and

Filter Exceeds Mass Limit

fabrication facilities

Before Reaching Expected

Differential Pressure

2/22/2000 All NRC licensed fuel-cycled

2000-02 Failure of Criticality Safety

conversion, enrichment, and

Control to Prevent Uranium fabrication facilities

Dioxide (U0 2) Powder

Accumulation

OL = operating License

CP = Construction Permit