radiological environmental protection (rep) program at slac · 4. slac environment, safety, and...

Radiological Environmental Protection (REP) Program at SLAC

James C. LiuDosimetry and Radiological Environmental Protection (DREP) Group

Radiation Protection Department (RPD)Environment, Safety and Health (ES&H) Division

Stanford Linear Accelerator Center (SLAC)

DOE Environmental Radiation Protection Program Review (July 23-24, 2007)

1

Contents

Overview of REP ProgramSLAC Facilities and AcceleratorsProgram Elements

General (Regulatory Drivers, Documents)Direct RadiationRadioactive AirIndustrial WastewaterStormwaterGroundwater

REP Program Goals and Current Efforts

2

REP Program Purpose

Ensure the impacts from radiation and radioactive materials from SLAC operations to general public and environment are:

below regulatory limits and maintained As Low As Reasonably Achievable (ALARA)

3

REP Program Purpose

Satisfy SLAC ES&H policies and best management practices (BMPs)Support SLAC programs by providing high-quality, accurate and timely radioanalysis servicesEnsure continual improvement and advancement of REP performance

4

SLAC Environment, Safety, and Health (ES&H) Division

5

Stanford Linear Accelerator Center (SLAC)

6

SLAC Accelerator Facilities

7

SLAC Accelerators and Beamlines

8

Potential Radiological Impacts

Off-site doses to the public from direct radiation, e.g., skyshine radiation Off-site doses to the public from airborne radionuclides released into the air environmentRadionuclides produced in soil and groundwaterRadionuclides in water that are discharged as sanitary wastewaterRadionuclides in the stormwater discharges

9

Key Radioisotopes of Interests

Medium Water Soil Air

Radionuclide 3H 7Be 3H 7Be 22Na 11C, 13N, 15O

20/10/2min

41Ar

Half-life 12.3 y 53.4 d 12.3 y 53.4 d

β+

511 keV

1.8 h2.60 y

Gamma GammaRadiationMeas.

β- Gamma β- Gamma

10

REP Program ISEMS Approach

Potential radiological impacts associated with each facility are evaluated during its design and pre-operational stages Appropriate engineered and/or administrative measures are evaluated and implemented to control/mitigate the potential impactsReviewed and approved by RSO/RSCImpacts are evaluated and/or monitored throughout the lifetime of facility for complianceSelf-assessment, improvement and advancement of REP program

11

REP Program Overview Radiological Environmental

Protection (REP) Program Elements

Direct Radiation Radioactive Air Effluents Radioactive Water Programs

Wastewater Stormwater GroundwaterActivated Air from

Accelerator

Accelerator-ProducedPhotons/Neutrons. Klystron Photons

7 PMS(pair of BF3 and GM)

PMS1PMS2PMS3PMS4PMS5PMS6PMS7~40 dosimeters

stations by SLAC

12 dosimeter stations by CA-DHS

Annual ASER report

NESHAPs report to

EPA

8 AMSPeriodic

confirmatorymonitoring

Annual NESHAPS

report.

Annual ASER

Industrial Wastewater Discharge

Permit: SBSA

Samplingprior to batch

discharge.

LSC & Gamma Spec as needed.

LCW sampledby CEF

Quarterly report to SBSA.

Annual ASER

SWRCBPermit

EPD counterpart:Storm Water

Pollution PreventionProgram,(SWPPP)

2 Storm water sampling events per wet season.

LSC & Gamma Spect as needed

Sampled by EPD

Annual ASER

RWQCDOrder

EPD counterpart:

Self Monitoring

Program

More than 100 wells.

~20 wells for radiological monitoring

Sampled by EPD and RPD

Annual ASER

12

SLAC WSS for REP Programs

GeneralProgram

Directn, γ

RadioactiveAir

Wastewater Stormwater Groundwater

Primary Law

10CFR20D

CCR17

DOEOrder

5400.5450.1

231.1A

5400.5 5400.5 5400.5 5400.5 5400.5

Limit 100mrem/y

10 mrem/y to MEI

5 Ci/y for 3H Others 1 Ci/y

Reference Level

10 mrem/y

0.1 mrem/y from each point

MCL: 4 mrem/y(20 pCi/mL 3H )

ES&H Manual Ch 9; REP Manual; Manuals and Procedures for program elements; RSS

Clean Air Act(42USC7401)

Clean Water Act (33USC1251)Safe Drinking Water Act (42USC1412)

Secondary Regulation

40CFR61H(NESHAPs)

10CFR20K 40CFR122(NPDES)

40CFR141(NPDWR)

State &Local

BAAQMD CCR17SBSA Permit

SWRCBPermit

RWQCBOrder

SLAC

13

Evaluation, Monitoring and Reporting for REP ProgramsDirect

RadiationRadioactive

AirGroundwater Wastewater Stormwater

Evaluation Annual beam losses

Shielding design using SKYSHINE

and/or Monte Carlo codes

Annual beam losses

Dose calculated with CAP88 code

Annual beam losses

Shielding design.Figures 5.5, 5.6,

and 5.7

LCW & sump system

design

Water should not flow through

accelerator tunnel

Facility DesignGuideline

5 mrem/y(7200 h/y)

0.1 mrem/y for each

release point

ALARA(MCL if

drinking water)

SBSA Limits None

Monitoring 7 PMS stations (continuous)Figure 5.4

~40 dosimeters (continuous)

Figures 5.1, 5.2, 5.3

8 AMS stations(as needed)Figure 4.3

~ 110 wells~90 (6-month)

20 guard wells for RP.

2 (monthly)2 (quarterly)

Figure 5.7

Sampling for all discharges

into the 4 wastewater release points

Sampling twice from October to

May for 8 discharge

points.Figure 4.2

Reporting ASER (June)

RPDosimeters

PMS(quarterly)

ASER (June)

NESHAPs(June)

ASER (June)

RWQCB(May, Nov.)

RWQCB(BDE H-3 RI/FS)

SLAC (quarterly)

ASER (June)

SBSA(quarterly)

ASER (June)

RWQCB(June)

14

REP Programs Documentation System

Direct Radiation

Radioactive Air

Groundwater Wastewater Stormwater

RE-100 1

RP-04-22 2

RE-020 3

RE-022 4RE-021 5

This ManualEPD-

SMPSAP 6

DH-004 7RE-018 8RE-019 9

This Manual DH-004 7

EPD-SWPPP 10

1) H. Tran, “Assessment of potential direct radiation dose to public”, SLAC Radiation Protection Department, RE-100, 10-10-06.

2) C. Copper, et. al., “Set-up and calibration of SLAC’s Peripheral Monitoring Stations”, SLAC RP Note, RP-04-22, 08-13-04.3) M. Kerimbaev, et. al., “Data post processing for SLAC’s Peripheral Monitoring Stations (PMS)’, SLAC RP Department

RE-020, SLAC-I-780-2A39C-017-R000, 01-12-06.4) Henry Tran and James Liu, “SLAC National Emission Standards for Hazardous Air Pollutants (NESHAPs) Program

Technical Manual”, SLAC Radiation Protection Department, RE-022, June 15, 2007.5) M. Kerimbaev and J. Liu, “Technical Basis Document for SLAC Air Monitoring System”, SLAC Radiation Protection

Department, RE-021, May 31, 2007.6) Environmental Protection Department (EPD), Field Sampling Plan for the Remedial Investigation and Feasibility Study

(SLAC-I-750-2A17M-009, May 2006), Appendix A: “Self-Monitoring Program Sampling and Analyses Plan”, March 2006.7) J. Liu, et. al., ”Technical Basis Document for radioactivity limits in liquids as a result of activation or contamination”,

SLAC Radiation Protection Department, DH-004, SLAC-I-760-0A05-0-010, 02-27-07.8) J. Liu, J. Allan, and E. Nimmo, “Policy on release of water potentially containing radioactivity’, SLAC Radiation

Protection Department, RE-018, SLAC-I-760-2A39Z-001-R001, 06-09-05.9) J. Liu, J. Allan, and E. Nimmo, “Approving sanitary sewer release of water containing radioactivity: rationale and

process”, SLAC Radiation Protection Department, RE-019, SLAC-I-760-2A16Z-000 (draft 2007).10) Environmental Protection Department (EPD), “Stormwater Pollution Prevention Plan”, SLAC-I-750-0A16M-002, under revision,

July 2006.

15

Direct Radiation Program

1. Dose Evaluation during Design Phase

2. Dose Measurements during OperationA. Environmental Dosimeters (RE-100)

B. Perimeter Monitoring Stations (RP-04-22, RE-020)

16

Evaluation of Direct Radiation Doses

Design guideline: 5 mrem/y for each facilityPer RPD document: “Radiation Safety Systems, Technical Basis Documents”Public dose calculated using SKYSHINE code or Monte Carlo codes during facility design stage by Radiation Physics Group of RPDAnnual normal beam losses and operational time estimated by accelerator physicists

17

PEP-II Skyshine Radiation Calculations with MARS Code

10-1 10-2 10-3 10-410 1

106 10 5

103104 10-5102 10 0

10-1 10-2 10-3104 10 110 3 102 10 0

[mSv/h]Dose Rate [mrem/h]

A-A' cross section

Tunnel roof concrete

Air

Air

Air

1st-Qmagnet

Concrete Curtain-wallConcrete

Air detector at IR hall ceiling

Air detectors near floor

Air

C C'

B

B'

D D'

Dose Measurements with Environmental Dosimeters

Direct photon and neutron doses to public using DOELAP-accredited vendor service (quarterly exchange of 2 sets of dosimeters, Luxel+ & CR-39, at each location on site boundary)

19

Locations of Environmental Dosimeters

20

Perimeter Monitoring Station (PMS)

21

Radioactive Air Program

1. NESHAPs Program(Public Dose Evaluation, RE-022)

2. Air Monitoring Program(Radioactivity Measurements, RE-021)

22

40CFR61.H - NESHAPs

Use of EPA-approved atmospheric dispersion and dose calculation computer code, CAP-88Limit of 10 mrem/y to MEI of general publicContinuous monitoring for those release points > 0.1 mrem/y (major sources)Annual report to DOE and EPA by JuneRecords kept for > 5 yrsNo permit or prior approval for new or modified facilities if < 0.1 mrem/y

23

SLAC NESHAPs Methodology

1. Calculations of saturation activities of radionuclides (11C, 13N, 15O, 41Ar) produced for each release point of a facility (Ci/W):

More than 10 facilities at SLACEach facility may have more than one release pointYield (Ci/W/m) from optimum target based on IAEA Report 188Reasonable average air path for housingMonte Carlo calculations (e.g., using FLUKA, MARS or MCNPX) by simulating actual geometry of beam-target-housing may be performed to obtain more accurate and lower yield values

24


2. Calculations of total radioactivity release per year for each release point:

Reasonable accelerator operational scenarios (length of operation per year and annual normal beam losses)Reasonable air exchange rate for accelerator housing (no forced ventilation at SLAC)

3. MEI locations (where off-site public currently resides) relevant to each release point is then determined (more than 10 MEI locations at SLAC)

25


4. Calculations of off-site MEI doses and collective doses to the public population up to 80-km from SLAC:

Use of CAP-88 Annual releases of radioactivity (Ci/y)Local Bay Area meteorological dataMost recent census CY2000 population data

5. Maximum MEI dose and the collective dose to population are reported in annual NESHAPs and ASER reports

26

Results of Calculated

Radioactive Air Emission

and Doses

CY

Air Emission MEI Dose (mrem/yr)

***

Air Emission Collective Dose

(person-rem)

Radioactivity Released to

Air (Ci)

Limit 10 ** NA1985 N/A ** 1.38E-011986 N/A ** 0.00E+001987 N/A ** 0.00E+001988 N/A ** 0.00E+001989 2.40E-03 ** 0.00E+001990 1.40E-02 0.01 2.70E+001991 8.59E-02 0.07 6.74E+011992 6.83E-02 0.055 2.21E+011993 9.30E-03 0.012 2.09E+001994 3.10E-04 0.004 2.18E-011995 9.12E-04 0.0038 4.00E-011996 6.00E-04 0.0049 4.30E-011997 8.00E-04 0.0044 **1998 4.00E-04 0.0033 **1999 3.00E-02 0.26 2.70E+012000 3.00E-02 0.19 2.70E+012001 8.00E-02 0.23 3.28E+012002 8.00E-02 0.21 4.63E+012003 7.00E-02 0.19 4.00E+012004 6.00E-02 0.14 3.20E+012005 4.00E-02 0.20 6.10E+012006 0.12 0.70 1.69E+02

27

SLAC NESHAPs Results

MEI doses have been much less than 10 mrem/yAll release points at SLAC are “minor sources”Therefore, no continuous monitoring is required for all release pointsThe needed Periodic Confirmatory Measurements (PCM) have been conducted (e.g., AMS measurements at Positron Vault and BSY in CY2006 and 2007)

28

Periodic Confirmatory Measurements (PCM)

Annual evaluation of source terms, e.g., annual beam lossesPeriodic measurements using AMSPeriodic measurements using grab air sample

29

Air Monitoring System (AMS) at SLAC

30

AMS Results of Saturation Activity (mCi) in Positron Vault

(1-kW beam on positron target)

AMS IAEAC-11 0 0

N-13 15 40

O-15 20 74

Ar-41 1 0.5

31

Dose to Biota

DOE-STD-1153-2002: Voluntary Consensus Technical Standard adopted July 2002.

Purpose: provide guidance to DOE facilities so they can demonstrate that populations of plants & animals do not exceed NCRP/IAEA dose rates due to exposure to radiation or radioactive materials releases.

Aquatic animals should not exceed 1 rad/dayTerrestrial plants should not exceed 1 rad/dayTerrestrial animals should not exceed 0.1 rad/day

Monitoring results for on-site area dose and radioactivity levels in soil and water permit SLAC to demonstrate that potential dose impacts to populations of plants and animals remain well within these guidelines.

32

Results of Total Doses and Direct Radiation Doses

33

CYTotal Dose

to MEI(mrem/yr)

Direct MEI Dose(mrem/yr)

Population Dose(person-rem/yr)

Dose to Biota(rad/day)

Limit 100 NA NA 0.1 animal1996 4.55 4.55 5.02 **1997 4.20 4.20 6.85 **1998 4.60 4.60 9.93 **1999 4.45 4.45 17.42 **2000 5.63 5.63 14.72 **2001 5.30 5.20 21.00 **2002 2.08 2.00 19.40 0.0052003 0.10 0.10 1.20 0.0012004 0.10 0.10 1.20 0.0012005 0.25 0.20 0.90 0.0022006 0.40 0.40 0.70 0.002

Industrial Wastewater Program(DH-004, RE-018, RE-019)

34

Radioactivity in Wastewater (e.g., LCW)

In close coordination with other departments/groups (e.g., RP Field Operations and CEF) in determining the system as well as monitoring and discharge requirements

35

Beamlines at SLAC BSY and LCW Systems

36

Four Types of Wastewater at SLAC

Water from sumps and poly tanks, which collect water piped through accelerator housing (Table 1 and Table 2 in Appendix A of RE-018)Water collected in LCW systems on RPD LCW Radiological Status Sheet (Table 3 and Table 4 in Appendix A of RE-018)Groundwater pumped from wells that have been found to contain tritium (Table 1 in Appendix B of RE-018)All other water likely to contain radioactive materials (e.g. water used in an experiment that could produce or add radioactive material to the water)

37

Wastewater Program Policies

No water of the 4 types stated above shall be released to sewer unless it has been sampled, checked for radioactivity, and in some cases, approved for release by RPDUnder no circumstances may the 4 types of water stated above that may cause undue environmental impacts be poured or pumped into a well, into a storm drain, onto the ground, or added to any existing surface water

38

Stormwater Protection Program

Coordinate closely with SLAC site-wide stormwater protection program: EPD’s Stormwater Pollution Prevention Plan (SWPPP) and DH-004

39

Stormwater Catch Basin and Discharge Pointsnear RSY and PEP-II Ring Regions

Two Main Outdoor Storage Areas for Radioactive Materials (ESA fenced area and MSY/RAMSY)

40

SLAC Stormwater Monitoring Program

Eight out of 25 stormwater discharge points collect stormwater that flows through Industrial Areas are sampled by EPD twice each year during the raining season (Oct-May)Water in RAMSY stormwater sump is sampled by RPD prior to be pumped to the near-by stormwater drain in MSYRPD monitors H-3 and gamma activities of all samplesRegular field observations per SWPPP:

Monthly at 8 sampling locations during raining season (when it is raining)Quarterly at 25 discharge locations when it is not rainingAnnual site-wide compliance field evaluation of stormwater discharge BMP

41

Stormwater Program Policies

Facility should be designed and operated to minimize the amount of water flowing through accelerator housingAny water that flows through accelerator housing should not be discharged to stormwater and should be collected and/or discharged into sanitary sewerControls with system design on activity levels in various liquid systems should be considered to minimize the potential for environmentally significant discharge eventsPotential radioactive materials or wastes shall be stored properly such that there are no undue radiological environmental impacts to the stormwater discharges off-site

42

Results of Annual Discharge of Radioactivity into Sanitary Sewer and Stormwater Discharges

CYRadioactivity

Released into Sewer (H-3 in Ci)

Amount of Radioactivity in Stormwater (Ci)

Limit 5 NA1985 ** **1986 ** **1987 0.00E+00 **1988 0.00E+00 **1989 0.00E+00 **1990 0.00E+00 **1991 1.00E-01 **1992 0.00E+00 **1993 2.51E-03 **1994 1.71E-03 **1995 1.08E-02 **1996 3.39E-01 **1997 2.23E-02 **1998 7.18E-02 **1999 7.11E-03 **2000 2.40E-03 **2001 2.10E-03 **2002 3.80E-02 0.00E+002003 4.10E-04 0.00E+002004 2.00E-02 0.00E+002005 1.40E-03 0.00E+002006 1.20E-03 0.00E+00

43

Groundwater Protection Program

44

Elevation Contour and Flow Directionfor Groundwater at SLAC

45

Over 100 Groundwater Monitoring Wells

20 guarding wells for radiological monitoring (red dots)46

Evaluation and Measurements of Groundwater Impacts

Evaluation (by Radiation Physics Group)Potential impacts (mainly H-3) assessed with Monte Carlo codes during facility design stageAnnual beam losses, operation time, shielding effect, groundwater flow rate and dilution effects, Design guideline: MCL and ALARA

47

Evaluation and Measurements of Groundwater Impacts

Measurements (coordinated with EPD’s Self-Monitoring Program Sampling and Analyses Plan)

Over 90 wells are sampled for H-3 every half-year20 radiological-guarding wells are sampled for H-3 and gamma isotopes every half-yearSo far, 4 wells with positive H-3 (much less than MCL; sampled quarterly). These have been reviewed by RWQCB and appropriate actions have been initiated and tracked by SLAC, e.g., see “SLAC RI/FS Work Plan for RWQCB”

48

Environmental Clean-up & Decommissioning

RP DepartmentRecent projects of FFTB Preservation, Bone Yard clean-up, ESB clean-up.

49

Environmental Clean-up & Decommissioning

Available tools include:

MARSSIM: detailed approach to conducting radiation surveys of potentially contaminated sites & for doing statistical tests to interpret results. MARSSIM does NOT specify release limits for radionuclides in soil.

RESRAD: code often used by DOE and NRC to derive release limits for radionuclides in soil

50

REP Program Requirements

Maintain compliance to protect the public and environment from SLAC operationsAchieve ALARASatisfy SLAC ES&H policies and best management practicesMeet SLAC program and mission needsIntegrate requirements and recommendations into facility design and operationsEvaluate and/or monitor potential radiological environmental impacts with high-quality and confidence

51

REP Program Goals

World-Class Program PerformanceRecognized expertise and capabilityState-of-the-art methods and systems for evaluation and measurementsReliable, effective and efficient programsCertified REP program elements such as Radioanalysis Laboratory

Make requirements and recommendations for design and operations of facility to protect the environment and the public without causing unnecessary operations interference & cost

52

What exists now for DREP Programs

Programs are in compliance with requirementsControls and monitoring for potential impacts are in placeEstablished processes for the integration of requirements and BMPs into facility design and operationsPolicies, program manuals and procedures exist to guide the programsRoles, authorities and responsibilities for program elements aredefined and assignedSelf-assessment to identify program gaps and implement the corrective actions as well as continual improvements to program performance, e.g.,

Integrating REP programs in EMS process Better and formal communication and coordination with, and training for, line organizationsAdvancing environmental monitoring and impact assessment techniques and programs

53

Specific Current Efforts

Staffing, cross-training and advancement of group membersFormalize groundwater protection programAdvance PMS & air monitoring programsAdvance Radioanalysis Laboratory (including the database program)Formalize facility clean-up and decommissioning programs using processes that are protective, cost-effective, & consistent with all applicable standardsDevelop radioactive material management program in terms of proper characterization, usage, storage and disposal (using life-cycle approach)

54

END

55

Radioanalysis Laboratory

RPD operates SLAC Radioanalysis Laboratory for measurement & documentation of radioactivity in:

Liquids (wastewater, groundwater, stormwater, spills, oil, etc)Solids (soil, concrete, resins, metals, swipes for contamination checks, etc)

56


2 Liquid Scintillation Counter (LSC) are used to measure H-3 content in liquid samples

57


2 HPGe gamma spectroscopy units are used to identify and/or measure gamma-emitting radionuclides in solid and liquid samples

58