ALPHA Project Safety Assessment Document

Vladimir Anferov

Regulatory Requirements

SAD Contents

A Safety Assessment Document (SAD) must identify hazards and associated onsite and offsite impacts to workers, the public, and the environment from the facility for both normal operations and credible accidents [4.a.(1)]

The SAD must contain sufficient descriptive information and analytical results pertaining to specific hazards and risks identified during the safety analysis process to provide an understanding of risks presented by the proposed operations [4.a.(2)]

The SAD must provide appropriate documentation and detailed description of engineered controls (e.g., interlocks and physical barriers) and administrative measures (e.g., training) taken to eliminate, control, or mitigate hazards from operation [4.a.(3)]

Risk Assessment Methodology

1. Rate probability of each hazard (A<0.01/year, B=0.01 to 0.1, C>0.1/year)

2. Rate consequence/impact level (1-Low, 2-Medium,3-High)

Risk Matrix Risk Levels

3

2

1

A B C

High Unacceptable

MediumAcceptable with additional training

or administrative mitigations

Low Acceptable

Probability

Con

sequ

ence

Consequences / Impacts Values

DOE 5480.25 guidance defines negligible, minor and major impacts:

• “Major” is that level of impact at which permanent health effects or environmental damage could occur. (Criteria: injuries that require extensive professional medical attention; > 25 rem effective dose equivalent);

• “Minor” is that level of impact at which permanent health effects or environmental damage are not expected. (Criteria: minor injuries; 1 - 25 rem effective dose equivalent);

• “Negligible” is that level of impact at which the potential for health effects or environmental damage is very slight. (Criteria: injuries requiring only superficial professional medical attention; < 1 rem effective dose equivalent).

SAD Summary

No Hazard Event Probability Level

Consequence Level Risk Level

Ionizing Radiation Hazards

1 Exposure to Ionizing radiation outside the accelerator enclosure

Low Medium Low

2 Exposure to Ionizing radiation inside the accelerator enclosure

Low Medium Low

3 Exposure to Ionizing radiation from activated components inside accelerator enclosure

Extremely Low Medium Negligible

4 Exposure to X-ray radiation produced by Klystrons

Low Medium Low

Non-Ionizing Radiation Hazards

5 Fire hazard inside or outside the accelerator enclosure

Low Low Negligible

6 Electrical shock Low Medium Low

7 Exposure to non-ionizing microwave leakage from Klystrons

Low Low Negligible

8 Exposure to high magnetic fields Medium Low Low

9 Laser light exposure Extremely Low Low Negligible

10 Exposure to toxic or carcinogenic materials (lead shielding)

Low Medium Low

11 Industrial accident involving construction machinery or falling objects

Medium Low Low

Radiation Protection

Radiation Sources:

• Linac exit• Injection beam line• Lambertson magnet• Ring section• Ring section• Ring section• Extraction beam line• Test area transport line• Sample position

Radiation Sources

Conversion Rates from NCRP Report 144:

Forward Gamma:

Leakage Gamma:

Neutrons:

kWPMeVEh

rem

dt

dDBeamBeam

4103

kWPh

rem

dt

dDBeam

3105

)40(1000 electronsMeVforkWPh

rem

dt

dDBeam

N

Attenuation in shielding barriers

Material Gamma Radiation Neutrons

Concrete(2.35 g/cm3)

TVL1=130 g/cm2 =

55 cmTVLe=113 g/cm2 =

48 cm

TVL = 97 g/cm2 = 41 cm

Iron(7.87 g/cm3) TVL = 85 g/cm2 =

10.8cmTVL = 290 g/cm2 = 37 cm

For 40-50 MeV electrons attenuation by a factor of 10 (TVL) :

Shielding Design Goals

Normal Operation: General public exposure limit in uncontrolled areas to

below 0.05 mrem/hr Users and Staff exposure limit in uncontrolled areas to

below 0.25 mrem/hr

Maximum Credible Incident• Integrated dose equivalent below 2 mrem outside the

shielding barriers.

Accelerator Safety Envelope

ASE = Operating Limits

Ref Beam Energy 50 MeV

Ref Beam Current 0.5 A

Ref Beam Duty factor 10Hz × 10sec

Maximum beam power 2500 Watts

ID # Source LocationNormal Op

power loss(%)MCI beam

Power loss(%)

1 Linac Beam Exit 1.0 100

2 Injection Beam Line 0.1 100

3 Lambertson Magnet 0.5 100

4 Ring Vacuum Pipe 0.01 100

5 Ring Vacuum Pipe 0.01 100

6 Ring Vacuum Pipe 0.01 100

7 Extraction Beam Line 0.1 100

8Test Area Transport

Line 0.1 100

9 Sample Position 100 100

Normal Operation

ID # Source Location Thickness Attenuation Factor Dose Rate (mrem/hr)

Concrete Steel Gamma Neutron Gamma Neutron Total

1 Linac Beam Exit 36 0 1.86E-06 5.05E-07 0.233 0.013 0.246

2 Injection Beam Line 36 0 3.24E-06 8.77E-07 0.041 0.002 0.043

3 Lambertson Magnet 36 0 3.24E-06 8.77E-07 0.203 0.011 0.214

4 Ring Vacuum Pipe 36 0 5.66E-07 1.53E-07 0.001 0.000 0.001

5 Ring Vacuum Pipe 36 0 2.36E-06 6.39E-07 0.003 0.000 0.003

6 Ring Vacuum Pipe 36 0 5.90E-07 1.60E-07 0.001 0.000 0.001

7 Extraction Beam Line 36 0 3.24E-06 8.77E-07 0.041 0.002 0.043

8 Test Area Transport Line 36 0 2.17E-06 5.89E-07 0.027 0.001 0.029

9 Sample Position 60 2 1.62E-08 3.96E-09 0.203 0.010 0.213

Maximum Credible Incident

ID # Source Location Dose Rate (mrem/hr)

Gamma Neutron Total

1 Linac Beam Exit 23.309 1.261 24.570

2 Injection Beam Line 40.532 2.193 42.725

3 Lambertson Magnet 40.532 2.193 42.725

4 Ring Vacuum Pipe 7.077 0.383 7.460

5 Ring Vacuum Pipe 29.500 1.596 31.096

6 Ring Vacuum Pipe 7.375 0.399 7.774

7 Extraction Beam Line 40.532 2.193 42.725

8 Test Area Transport Line 27.187 1.471 28.658

9 Sample Position 0.203 0.010 0.213

MCI represents loss of an entire beam in a single accelerator component (location).

Conclusions

• SAD lists all hazards

• Ionizing radiation hazards are mitigated by shielding design, interlock system, beam loss monitoring and training.

• Non-ionizing radiation hazards are mitigated by following safety codes and training.