Help me out here gang. I'm trying to assess the severity of this incident. I've assumed that it was fairly serious due to the notification of FEMA and an emergency declaration. This problem appears to be very similar to the scenario painted by Gunter in his testimony (Exhibit A). It appears that the trip/fault/whatever identified in Exhibit B lead to the switchover to a backup battery. This is confirmed in Exhibit C if we are to believe Reuters. Did this incident last long enough to drain the battery? If so, is that why the annunciators failed? What were the implications if they had not fixed it in time? Calling all nukeheads please give me some real info here.

Exhibit A Paul Gunter's testimony

"Emergency power must be generated onsite to maintain reactor core stability through the removal of this 'residual heat' via a system of circulating coolant pumps and motor operated components. Additional safety-related monitoring and control systems require electrical power stored and generated on-site. Emergency Diesel Generators are designed to provide back-up electrical power and charge onsite auxiliary batteries necessary for the duration of any grid instability or failure."

The gravest danger inherent at nuclear power plants is the simultaneous failure of both the electrical power grid and the onsite Emergency Diesel Generators (EDG). According to Mr. Gunter, this condition, known as "station blackout," is regarded by the Nuclear Regulatory Commission as the largest postulated contributor to reactor accidents resulting in fuel damage. He explained,

"A station blackout of long duration (in excess of 2 hours) leads to auxiliary battery depletion for AC conversion and subsequent loss of vital instrumentation and control features. The uncovering of the reactor core and its associated hazards can occur within a range of 3 to 10 hours beyond the time of battery depletion without restoration of AC power...with the combination of grid failure, battery failure and EDG failure 'core damage begins in approximately one hour as the result of coolant boiloff' or uncovering the core for some reactors. Core damage can be expected to proceed to a core melt if effective and timely measures to restore AC power and core cooling are not taken or available..."

Mr. Gunter continued, "NRC studies consider a long duration blackout event in excess of two hours to be a dominant factor influencing the likelihood of core damage or a core-melt accident. Long-term or recurring grid failure as a result of Y2K vulnerabilities has not been sufficiently studied."

Exhibit B (NRC Incident Report):

Buses 2A, 3A, and 5A are currently being supplied by the EDGs; however, the output breaker for EDG 23 tripped upon loading to bus 6A, which remains deenergized. Operators manually started the turbine driven auxiliary feedwater pump due to the loss of control power to one of the motor driven AFW pumps caused by the loss of bus 6A.

Exhibit C (Reuters Article)

A few minutes after the trip, the plant's three emergency diesel generators automatically activated as expected. However, one of the generators failed to load properly, leading to the eventual draindown of a battery that serves as a backup power source.

-- Anonymous, September 10, 1999

Answers

Jim, have you seen the thread below entitled "Emergency Declared at Nuke this past weekend, FEMA notified and WACO smokescreens?" at:

http://www.greenspun.com/bboard/q-and-a-fetch-msg.tcl?msg_id=001LLS

There are more details and a link to an NRC press release there that I posted. This was classified as an Unusual Event, the lowest of the four classifications used, but whether there was a real danger in the situation worsening, I just don't know without having more information (I am not familiar with their bus and EDG arrangments).

I will repeat the press release here: The NRC issued a press release, posted below: ---------------- From: http://www.nrc.gov/OPA/gmo/nrarcv/99-73i.htm

No. I-99-73 FOR IMMEDIATE RELEASE September 2, 1999 NRC SENDS INSPECTION TEAM TO INDIAN POINT 2 NUCLEAR POWER PLANT

The Nuclear Regulatory Commission has dispatched a four-person team of inspectors from its Region I office in King of Prussia, Pa., to the Indian Point 2 nuclear power plant to look into the causes of and plant response to a reactor trip with complications that occurred on Tuesday and led to the declaration of an Unusual Event.

Known as an Augmented Inspection Team (AIT), it will be charged with learning the facts surrounding the event.

All of the AIT members should arrive at the Buchanan, N.Y., plant by sometime today. The team's findings will be available and made public about 30 days after completion of its on-site reviews.

At 2:30 p.m. on Tuesday, Indian Point 2 experienced a trip, or an automatic shutdown, after the receipt of a spurious signal in a reactor protection system. A few minutes after the trip, the plant's three emergency diesel generators, which provide power in the event of the loss of off-site power, automatically activated after they received a signal indicating that insufficient voltage was available to some plant safety systems.

However, one of the emergency diesel generators failed to load properly and that led to the eventual draindown of a battery that serves as a backup power source. In turn, the plant lost a number of its control room annunciators, or alarm panels. In response, plant operators declared an Unusual Event -- the lowest of four levels of emergency classification -- at about 9:55 p.m. The annunciators were restored at about 1:30 a.m. on Wednesday.

The reactor was stabilized and remains in hot shutdown. -------------- ----------

Regards,

-- Anonymous, September 10, 1999

You can find out more about this event at the NRC Region 1 meeting on Friday Sept. 17th near Philadelphia.

-- Anonymous, September 10, 1999

September 15, 1999

Dr. William Travers

Executive Director for Operations

United States Nuclear Regulatory Commission

Washington, DC 20555- 0001

SUBJECT: PETITION PURSUANT TO 10 CFR 2.206, INDIAN POINT UNIT 2, DOCKET NO. 50-247

Dear Dr. Travers:

The Union of Concerned Scientists submits this petition pursuant to 10 CFR 2.206 requesting that the operating license for Indian Point Unit 2 be modified or suspended to prevent restart until there is reasonable assurance that its licensee is in substantial compliance with the terms of the plant's operating license and has proper consideration for public health and safety. As detailed in the attachment, the August 31, 1999, near-miss at the facility revealed a number of apparent non-conformances with very serious safety implications. Adequate protection of public health and safety dictates these problems be fully resolved before the plant resumes operation. UCS additionally requests a public hearing into this matter be held in the vicinity of the Indian Point Unit 2 facility prior to its being authorized to restart.

Background

On September 28, 1973, the Atomic Energy Commission (AEC) issued an operating license to Consolidated Edison Company of New York, Inc. for Indian Point Unit 2. The AEC issued that license after having determined, among other things, that:

"The facility will operate in conformity with the application, as amended, the provisions of the Act, and the rules and regulations of the Commission.

"There is reasonable assurance:  (ii) that the activities authorized by this operating license can be conducted without endangering the health and safety of the public, and (ii) that such activities will be conducted in compliance with the rules and regulations of the Commission."⁽¹⁾

Thus, the operating license for Indian Point Unit 2 was granted partly on the explicit assumption that the licensee would operate the facility in conformance with the rules and regulations of the AEC (now NRC).

The reactor at Indian Point Unit 2 automatically shut down at 2:30pm on August 31, 1999. Shortly after the reactor tripped, an undervoltage condition was sensed on the 480 volt safety buses. This caused all three emergency diesel generators (EDGs) to automatically start and to connect to their associated 480 volt safety buses. However, the output breaker for one of the diesel generators (23 EDG) re-opened immediately after closing to connect that EDG to its safety bus (6A). The output breaker failure left 480 volt safety bus 6A powered solely from its associated battery (24 DC Battery). Approximately seven (7) hours later, 24 DC Battery was discharged leaving 480 volt safety bus 6A de-energized and causing the loss of instrument bus 24. The loss of this instrument bus disabled approximately 75 percent of the annunciators in the control room, which triggered the declaration of an emergency condition. Power to 480 volt safety bus 6A was restored around 1am on September 1, 1999 when 23 EDG was re-connected.⁽²⁾

Basis for Requested Actions

UCS reviewed the publicly available information on this event. UCS also reviewed the publicly available information on the design and licensing bases for safety equipment whose operation or mal-operation contributed to the severity of this event. Finally, UCS attended the public meeting held in the NRC's Region I offices on September 14, 1999, during which the owner of the plant explained what had happened. As detailed in the attachment, there are at least four apparent violations of the plant's design and licensing bases revealed by the August 31, 1999 event:

Issue 1 - Apparent Violation of Station Battery Design and Licensing Bases

Issue 2 - Apparent Failure to Adequately Correct Circuit Breaker Problems

Issue 3 - Apparent Unreliability of Emergency Diesel Generators

Issue 4 - Potentially Unjustified License Amendment for Undervoltage and Degraded Voltage Relay Surveillance Intervals

In addition, the event revealed potential problems with the plant-specific risk assessment developed by the licensee and now used to establish priorities:

Issue 5 - Apparent Errors and Non- Conservatisms in Individual Plant Examination

1.

⁰ United States Atomic Energy Commission, Facility Operating License, License No. DPR-26 Amendment No. 4, September 28, 1973.

2.

⁰ Nuclear Regulatory Commission, Preliminary Notification of Occurrence PNO-I- 99-040, September 1, 1999.

-- Anonymous, September 15, 1999