2010 Accelerator Safety Workshop

August 18, 2010

Lessons Learned Breakout

A. Ackerman

2 BROOKHAVEN SCIENCE ASSOCIATES

Lessons LearnedOverview

• Program utility and value is obvious• Share experience• Learn from mistakes

But, also brings some concern:

• Can be misunderstood/misinterpretated• Not everyone reads all• Hard for people removed to understand/appreciate

• Hard to disseminate the message with just email.

Solution:• Write carefully

• Short; one page max• Salient points up front• Provide a contact for detail• Lessons Learned Coordinators

3 BROOKHAVEN SCIENCE ASSOCIATES

Accelerator Test Facility (ATF; Bldg 820) Overview

• Accelerator Test Facility• 70 MeV electron Linear Accelerator (LINAC)• Four beam lines• Electron / Laser interaction research / testing

• S-Band LINAC• 2 Klystrons • Pulse forming network (PFN) provides power to drive the klystrons• Modulators include capacitors, inductors, thyratron• Plastic capacitors; can arc and ignite

4 BROOKHAVEN SCIENCE ASSOCIATES

ATF; The Fire

5 BROOKHAVEN SCIENCE ASSOCIATES

ATF Fire Lesson LearnedText (294 words)

On Wednesday, February 18, 2009, a fire started at the Accelerator Test Facility (ATF), at Brookhaven National Laboratory (BNL). The fire was limited to the klystron modulator pulse-forming network (PFN) of the linear accelerator (linac) and associated electronics; resulting in negligible environmental impact. The PFN and its thyratron switch tube were destroyed beyond repair. The subsequent incident investigation listed a failed capacitor in the PFN as the cause of the fire. The ATF Linac is not operational while the PFN is being redesigned and rebuilt with more robust components. Restart is scheduled for sometime in the summer of 2009.

The ATF fire investigation concluded that capacitors, when used in this application at BNL, are known to have early life catastrophic failures. The investigation indicated that this was due to oversights in the design of the PFN’s; including the lack of capacitor monitoring, inspection techniques, and fire prevention measures. The team also acknowledged the thoughtful and careful response by personnel at the scene. Their swift actions helped contain the damage and protect personnel. No one was hurt.

6 BROOKHAVEN SCIENCE ASSOCIATES

ATF Fire Lesson LearnedText (294 words)

An engineering working group has been formed to gather experience at BNL and other DOE facilities to evaluate fire prevention measures for this and similar pulsed power equipment. It is clear that more analysis and design review is needed for these systems as this event at the ATF is the fifth fire at BNL involving the same or similar model capacitors. Each involved the degradation of capacitors over time that led to a fire and prompts a general concern for:

• Monitoring, inspection, and preventive maintenance of capacitors in high voltage pulse forming networks and; 

• A reminder to include fire safety concerns in high power equipment designs at operating accelerators.

BNL Contact for more information: XXX