# Presentation: 249213

## NSLS-II Shielding Workshop

- R. Casey
- Introduction & Shielding Objectives
- March 27, 2007

## Welcome and Agenda

- 0830 - Welcome and Overview of NSLS-II Design
- 9:00 - Review of Workshop & Discussion of Shielding Objectives for NSLS2
- 1000 - Break
- 1015 - Bulk Shielding Calculation Methodology
- 1115 - Beam Loss Assumptions, Source Terms and Attenuation Lengths
- 1200 - Lunch
- 1300 - Summary of Bulk Shielding Design
- 1400 - Engineering Controls - Area Monitoring/Beam Loss Monitors
- 1500 - Break
- 1515 - Critical Devices and Interlocks
- 1630 - Committee Discussion
- 1800 - Dinner

## Agenda (cont.)

_**Wednesday, March 28**_
- 0900 - Shielding design of beam lines
- 1000 - Break
- 1015 - Soil, Water and Air Activation
- 1100 - Committee Session
- 12:00 - Lunch
- 1300 - Close Out

## Objectives of Workshop

- We are looking for feed-back from experienced radiation safety professionals who have gone through this before
- It is a good time for input and feedback – we are just now going to preliminary design
- Very important to get shielding right – it is expensive to install, but even more expensive and hard to correct later
- Work shop is broader than shielding – engineering controls, interlock systems, environmental issues

## Objectives of Workshop (cont.)

- Confirm adequacy of methodology & input parameters
- Evaluate assumptions
- Machine is still changing – methodology and assumptions more important at this time than the results – we will be interested in your opinion of our final calculations in a year or so
- Provide lessons learned from your experience
- Brief written report summarizing your comments

## Preliminary Shielding Design Documents for NSLS II

- 1. Linac, NSLS II- TN 12
- 2. Booster & Storage Ring, NSLS II – TN 13
- 3. Storage Ring Supplemental Shielding – TN 21
- 4. Beamlines and Front Ends, NSLS II – TN 14
- 5. Ray Tracing Standards, NSLS II – TN 20
- 6. Activation Analysis, NSLS II – TN 15 & 16

## Machine is Evolving – a few months back

## A few months back

- Linac Area

- RF Area

## Current Rendering of Facility

## Slide 10

## Booster 1st Floor

## Booster 2nd Floor

## Site Plan

## Key Assumptions and Shielding Policy for  NSLS – 2  Shielding Calculations

## Key Assumptions

- 200 MeV, 20 nC/pulse, 1 pulse/s – Linac
- 3.5 GeV, 15 nC/pulse, 1 pulse/s Booster
- 3.5 GeV, 500 mA Storage Ring
- Life-time – 2 hours
- Top-off ~ 1 minute to maintain current variability < 1%
- Other key assumptions
- Shielding dose criteria & occupancy factors
- Loss rates
- Source terms
- Attenuation lengths

## A key change in one assumption since the Notes

- 0.25 mRem/hr at 1 meter from wall rather than in direct contact with wall
- This change permitted the designers to use ordinary concrete in most areas of ring rather than heavy concrete

## Desired Shielding Outcome

- Compliance with DOE Orders, Part 835, and BNL Administrative Controls
- < 25 mRem/year on-site to non-NSLS-II personnel; < 5 mrem/year at site boundary
- Radiation exposure to users and staff ALARA – an administrative control level of 100 mRem/year is desired
- We plan to achieve this through shielding and engineering & supplemental administrative controls
- Based on current experience, we expect annual radiation exposures < < 100 mRem/year to NSLS staff and users
- After verification, we expect short-term visitors will not be required to have dosimeters routinely

## Shielding Policy

- Accelerator enclosures & hutches shielded to 0.25 mRem/hr; i.e. 500 mRem/year based on 2000 hours of exposure per year at 1 m from the exterior of the shield (< DOE Design Goals stated in 10 CFR 835.1002)
- Hutches are being considered further for 0.05 mRem/hr
- They potentially represent a more significant source of exposure
- Personnel more likely to be in vicinity of hutches

## Shielding Policy (cont.)

- Calculations use conservative assumptions and source terms
- Abnormal operating conditions, including Maximum Credible Incidents (MCI), are evaluated
- Additional engineering or administrative controls are specified based on severity of radiation levels under fault conditions.
- Shielding and controls are considered adequate if MCI has low potential for exceeding 100 mRem and can not exceed 2000 mRem

## Shielding Policy (cont.)

- Engineering control options include:
- Additional shielding (e.g. shadow shields, localized shields)
- Beam loss monitors with alarm in control room and (perhaps) interlock function
- Beam current monitors with alarm in control room and (perhaps) interlock function
- Area radiation monitors at the occupied areas with alarm locally and in control room and interlock function

## Shielding Policy (cont.)

- Supplemental Administrative control options include:
- Operational procedures for operators and ESH staff during injection and routine operations
- Commissioning and shielding verification procedures
- Shielding configuration control
- Review of accelerator and beam design modifications
- Survey and posting procedures
- Passive area monitors