MI Shielding Machine Protection Credit D. Capista March 7,2010

Accident Analysis  Determine the most likely value of dNbeam/dt and its upper limit for each scenario. The upper limit compared with the most likely value may be useful to determine the uncertainty in the analysis.  Determine the most likely values of Δt beam and its upper limit for each scenario. The upper limit compared with the most likely value may be useful to determine the uncertainty in the analysis.  In all scenarios, any beam loss over 10% of full intensity (5E13), will most likely trip the machine in a single pulse.  A single point loss will trip with much less than 10% loss  There exists a case, in all scenarios, where due to equipment and administrative failures, the entire beam can be lost repeatedly for extended periods of time.

Accelerator Shielding Controls Credited Controls – Passive Controls Concrete, Steel, Earth, Radiation Fencing – Active Controls Radiation Safety System – Enclosure Interlocks – Radiation Monitors » Chipmunks, Scarecrows, Foxes Current philosophy requires a combination of Credited Passive and Active controls based on area occupancy. Question becomes how can we utilize the machine protection systems. Beam Loss Scenario Panel Meeting JEA

Pae 4 Defense-in-Depth Strategy Beam Loss Scenario Panel Meeting JEA Administrative Controls Credited Controls Risk Matrix Process Controls

Non Credited Controls Beam Loss Scenario Panel Meeting JEA Maximum Dose (D) Expected in 1 hour Controls D  1000 mrem Prior approval of SRSO required with control measures specified on a case-by-case basis. 500  D  1000 mrem Signs (DANGER -- High Radiation Area) and 8 ft. high rigid barriers with interlocked gates or doors and visible flashing lights warning of the hazard. Rigid barriers with no gates or doors are a permitted alternate. No beam-on access permitted. Radiological Worker Training required. 100  D  500 mrem Signs (DANGER -- High Radiation Area) and rigid barriers (at least 4' high) with locked gates. For beam-on radiation, access restricted to authorized personnel. Radiological Worker Training required. 5  D  100 mrem Signs (CAUTION -- Radiation Area) and minimal occupancy (duration of occupancy of less than1 hr). The Division/Section/Center RSO has the option of imposing additional controls in accordance with Article 231 to ensure personnel entry control is maintained. Radiological Worker Training required. 1  D  5 mrem Signs (CAUTION -- Controlled Area). No occupancy limits imposed. Radiological Worker Training required. 1 < D < 10 mremMinimal occupancy only (duration of credible occupancy < 1 hr) no posting D  1 mrem No precautions needed.

Accident Conditions with Machine Protection Beam Loss Scenario Panel Meeting JEA Maximum Dose (D) Expected in 1 hour Machine Controls D  1000 mrem 500  D  1000 mrem 100  D  500 mrem 5  D  100 mrem 1  D  5 mrem 1 < D < 10 mrem D  1 mrem 2 Machine Protection Controls 4 Machine Protection Controls Credited Controls Always required SRSO Approval Required with Control Measures Specified on a Case-by-Case Basis.

MI Machine Protection Controls  Main Control Room Occupied 24 hrs a day, 7 days a week by Operations. Machines are monitored by both operators and experts. Has several dedicated displays for monitoring accelerators such as the beam budget monitor.  Machine Timing ( Time Line Generator) Timing modules consist of a structure of clock events that cause accelerators to function in a defined manner. Timing modules are created by machine experts and approved for use by experts. Accelerator operators load approved modules for machine scenarios.  Beam Sync clock system Monitors accelerator clock structure and beam permits and determines whether or not to issue a beam transfer event. These beam transfer events will transfer beam from one machine to another. If the event does not occur, beam is sent to the abort.

MI Machine Protection Controls  Beam Permit system ( abort loop) Accepts digital inputs form devices and determines if beam can be present in the accelerator. The system will abort beam if the loop drops when beam present. MCR has abort buttons at most consoles.  Beam Switch Sum Box (BSSB) Monitors Accelerator clock structure, beam permits, and beam switch requests for beam and determines whether to start the acceleration process at the Preacc.  For a list of approved machine scenarios, clock definitions, and other documentation:

MI Machine Protection Controls  Orbit Control Beam orbit is monitored by operators / experts and smoothed to a desired set of positions using a console application program. In the MI8 beam line some of the positions, around the collimators, are automatically controlled with an autotune program running. For NuMI extraction, beam positions are verified, at high energy, before the extraction kicker is fired. If these positions are not correct, the beam is aborted and the beam permit will drop out.  Beam Loss Monitors One monitor is located no less than ever three magnets. If the integrated loss exceeds a limit on a cycle the abort is pulled at the end of the cycle by pulling the beam permit loop. If the instantaneous loss exceeds a limit during a cycle the beam is aborted by pulling the beam permit loop.

MI Machine Protection Controls  Power supply monitoring. All major power supplied in the ring and beam lines are connected to the beam permit system. In some cases these are digital on/off status and in other cases the flat top value is compared to a nominal value.  Vacuum system. The ion pumps are monitored by a local crate and if the vacuum pressure is too high, the vacuum valves are closed to protect the machine, and the beam permit is pulled.  Machine design and geometry. The MI has been designed in a way that makes it difficult to directly hit a component directly.