1 / 13

Review of May 29 Excursion

Review of May 29 Excursion. Bob Casey. Injection Building. Local Control Room. Booster (only arc 1 installed). Equipment Racks for Linac and LTB line. Klystron Gallery. Linac Tunnel. Closeup of Linac and Booster Tunnel. 100 MeV beam bent too far.

luther
Download Presentation

Review of May 29 Excursion

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Review of May 29 Excursion Bob Casey

  2. Injection Building Local Control Room Booster (only arc 1 installed) Equipment Racks for Linac and LTB line Klystron Gallery Linac Tunnel

  3. Closeup of Linac and Booster Tunnel 100 MeV beam bent too far. 1.7 R/h in localized spot on the booster wall Monitors alarmed locally Interlocked monitors did not see levels large enough to alarm or trip Controlled Area Equipment not installed here MON MON MON MON LB-B2 LOTO Safety shutter LOTO Penetration fulled with lead Beam Dump 2 LB-B1 dipole Beam Dump 1

  4. Statement of the event • While operating at 100 MeV, the power supply for the D1 bending magnet was inadvertently ramped to full power, bending the electron beam beyond the extent of the shadow shield and permitting the beam to strike the linac side wall. • No radiation exposure to personnel resulted from this event. The area affected by the increased radiation levels was posted as a controlled area with radiation monitors providing local alarms.

  5. Zoom in to the shielding Beam direction

  6. As seen from the top of the dipole This was the existing shield This is the upgraded shield Beam went this way

  7. Events of 5/29/12 • Operator tuning machine with 100 MeV beam energy at 15 nC/s current while commissioning “beam loading compensation” in the linac. • Legitimate but uncommon method of commissioning this mode of operation. • While steering the beam to beam dump 2, a typographical error caused the dipole to ramp up to its maximum current. • This combination caused the beam to bend 4 times more than designed • Beam misses downstream shield walland created radiation levels in tunnel which caused local alarms

  8. Events (cont.) • Two electrical workers inside the tunnel but outside of the controlled area heard local alarms and went to the control room. • GERT trained, wearing TLD, did not go through the controlled area. • Operators responded according to procedure and informed RCD personnel. • While RCD en route, operators tried to diagnose the alarm. Told workers to remain out of the tunnel. • RCD verified the high alarm levels. Immediate investigation showed no dose at location of workers. RCD instructed operators to terminate the beam. • Operators terminate the beam and shut off the linac until further approval. • Total time ~ 45 – 50 minutes.

  9. Subsequent Events • LCC and ESH immediately advised. It was decided to reproduce the scenario after work and obtain a more comprehensive radiation survey. • With the power supply at full power, and the electron beam at 100 MeV and 15 nC/s, levels as high as 1.7 R/h in contact with wall were measured. • Multibunchoperation was immediately suspended until corrective actions taken.

  10. Area Monitor 5-29-12

  11. Radiation Levels and Dipole Current During Event

  12. Supplemental Shield Design Assumptions Supplemental shield was designed to prevent levels > greater than 5 mr/h in the Booster tunnel from a miss-steered 22 nC/s electron beam at 230 MeV striking the lead shield. It was not designed to intercept a 100 MeV beam when the dipole was powered to full current.

More Related