nsls2 bulk shielding calculations methodology

1 BROOKHAVEN SCIENCE ASSOCIATES

NSLS2Bulk Shielding calculations Methodology

P.K. JobRadiation PhysicistPeer Review 2007

March 27, 2007


Outline

• Source Terms due to beamloss• Radiation Attenuation Lengths• Beamloss assumptions• Bulk Shielding calculation Methodology• Beam Stop Calculation Methodology• Skyshine Calculations


Radiation Types Considered

• Bremsstrahlung from electron beamloss• Bremsstrahlung produced neutrons by Giant Resonance

Interaction• Bremsstrahlung produced high energy neutrons


Bulk Shielding Calculational Tools

• Swanson’s Empirical Method• Sullivan’s Modification (CERN)• Shield 11 Program Based on Empirical Method• EGS4 Monte Carlo Electron-Gamma Shower Program


Empirical Method (Swanson)Radiation Dose Equivalent Factors

Thick target bremsstrahlung source term due to electron beam loss as a function of scattering angle is given by Swanson


Radiation Dose Equivalent Factors at 900

(comparison)

Radiation Component

Dose equivalent factors(mrem.m2/J)

(Swanson)

Dose equivalent factors(mrem.m2/J)(Sullivan)

Dose equivalent factors(mrem.m2/J)(Shield 11)

Bremsstrahlung 2.80 1.39 1.12

Giant Resonance Neutrons

0.63 0.27 0.257

High Energy Neutrons

0.075 0.043 0.068


Empirical MethodRadiation Dose Equivalent Factors at 900

(used for the calculations)


Radiation Dose Equivalent Factors(used for the calculations)

At 00 ( in the direction of the beam) = 8.3 E mrem.m2 / J

In the forward direction (other than 00) = 0.85 rem.m2 / J

These factors are same for all methods.


Radiation Attenuation factors(comparison)

Radiation Component

Shielding Material

AttenuationLength (Hub)(g / cm2)

AttenuationLength (Shiel)(g / cm2)

Bremsstrahlung ConcreteLeadIron

492537

4224

33.6

Giant Resonance Neutrons

ConcreteLeadIron

40161100

309747

High Energy Neutrons

Concrete

LeadIron

65115191138

55120200145


Radiation Attenuation factors(used for the calculations)


Storage Ring Beamloss Scenario 1


Storage Ring Beamloss Scenario 2


Storage Ring Beamloss Scenarios (Summary)


Beamloss Scenarios used for Calculations


Bulk Shielding Calculation Methodology


Beam Stop Calculation Methodology


Beam Stop Dimensions

Fe Beam Stop Dimensions for the 3.5 GeV e- Beam(to Contain 99 % of the EM Shower)

35 cm (20 X0)

4.2 cm (3 M)e- Beam Fe Cylinder


Skyshine Calculation Methodology


Skyshine Estimates due to Booster Beam Stop

nsls2 bulk shielding calculations methodology

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