Radiation Protection and
Safety in High-Energy
Physics
Kenneth R. Kase, Ph.D.
Associate Director, Environment, Safety and
Health (Retired)
Stanford Linear Accelerator Center
&
Senior Vice President
National Council on Radiation Protection
and Measurements
11 April 2005
5th International High-Energy
Physics Technical Safety Forum
1
Outline

Brief Overview of Radiation Protection
Standards
 Relationship of Radiation Safety to Other
Safety Concerns
 Current and Future Issues in Radiation
Protection Related to High-Energy Physics
11 April 2005
5th International High-Energy
Physics Technical Safety Forum
2
1925 Erythema Limit

Mutscheller: 1/100 erythema dose
in 30 days

Sievert: 1/10 erythema dose in
1 year

Threshold concept
11 April 2005
5th International High-Energy
Physics Technical Safety Forum
3
ICRU

Formed by the International Congress of
Radiology (ICR)

X-Ray Units Committee

Physical measurement required
11 April 2005
5th International High-Energy
Physics Technical Safety Forum
4
1928 “Roentgen” Defined

“Roentgen”: Proposed by the “Units”
Committee in 1925

Adopted by the ICR in 1928

“the exposure when the x-ray or
gamma-ray field produces 1 e.s.u. of negative
charge in 0.00129 gram of air”

ICRP and NCRP were formed
11 April 2005
5th International High-Energy
Physics Technical Safety Forum
5
1933-1934 Dose Limits
Established

ICRP
0.2 R/day

NCRP
0.1 R/day
11 April 2005
5th International High-Energy
Physics Technical Safety Forum
6
1941 New Information
 Excessive
radium use by the public via
patent medicines
 Radium
 0.1
11 April 2005
dial painters exhibit damage
g Radium Body Burden accepted
5th International High-Energy
Physics Technical Safety Forum
7
1949–1954 ICRP and NCRP

New Set of Weekly Dose Limits
 300 mR — blood forming organs
lens, gonads
 600 mR — skin
 300 – 600 mR — other organs
 1,500 mR — extremities (x rays)
 1/10 these values for minors
11 April 2005
5th International High-Energy
Physics Technical Safety Forum
8
Public Concern
 BEAR
 MRC
Committee (US National
Academy of Sciences)
Committee (UK Medical
Radiation Council)
 UNSCEAR
11 April 2005
(United Nations)
5th International High-Energy
Physics Technical Safety Forum
9
1957–1958 ICRP and NCRP

New Age-Related Worker
Limits

5 x (age – 18) rem/year,
 3 rem/13 weeks
(head, trunk, active blood forming organs, lens,
and gonads)
11 April 2005
5th International High-Energy
Physics Technical Safety Forum
10
1957–1958 ICRP and NCRP
 New
Population Limit
5 rem/30 years
(170 mrem/year)
Small groups — 0.5 rem/year
11 April 2005
5th International High-Energy
Physics Technical Safety Forum
11
1977 ICRP
 Examine
need for new limits
 Greatly expanded use
 New risk estimates
 Risk-Based Approach
11 April 2005
5th International High-Energy
Physics Technical Safety Forum
12
1977 ICRP Risk Estimates
 D
+ D2, i.e., linear at low doses
 Fatal
cancer risk coefficient
1 x 10-2 per Sv (1 x 10-4 per rem)
risk 0.4 x 10-2 per Sv
(0.4 x 10-4 per rem)
 Hereditary
[Note: 1 Sv = 100 rem]
11 April 2005
5th International High-Energy
Physics Technical Safety Forum
13
Approach to Worker Limit
(Stochastic)

Is 50 mSv/year acceptable?

Fatal accident rate in safe industries was
1 x 10-4/year
 Average dose to workers will be
<10 mSv/year (risk of 10-4/year)

50 mSv/year limit provides same level of
risk as safe industries
11 April 2005
5th International High-Energy
Physics Technical Safety Forum
14
1990–1993 ICRP and NCRP

New Dose Limits for Workers
 ICRP
 50 mSv/year maximum
 100 mSv/5 year (20 mSv/year)
 NCRP
 50 mSv/year maximum
 Age in 10’s of mSv
11 April 2005
5th International High-Energy
Physics Technical Safety Forum
15
Maximum Radiation Risks at
HEP Facilities

Annual exposures to almost all workers are
less than 5 mSv
 This results in an annual added risk for a
fatal cancer less than 3x10-4
 And an added lifetime cancer risk of 1% or
less
11 April 2005
5th International High-Energy
Physics Technical Safety Forum
16
Relationship of Radiation Safety
to Other Safety Concerns

Is it just another occupational hazard like
electricity, construction, high pressure,
vacuum, toxic chemicals and gases ?
 Does it need to be treated differently?
11 April 2005
5th International High-Energy
Physics Technical Safety Forum
17
Relationship of Radiation Safety
to Other Safety Concerns

Engineering and design
 Shielding
 Access control

Compare with electrical
11 April 2005
5th International High-Energy
Physics Technical Safety Forum
18
Current and Future Issues in
Radiation Protection

Radiation is a hazard that presents risks
similar to other industrial hazards at high
energy physics facilities
 It need not be treated differently from other
hazards.
 But, perhaps some of the principles used for
radiation protection could be applied to the
mitigation of other hazards
11 April 2005
5th International High-Energy
Physics Technical Safety Forum
19
Current and Future Issues in
Radiation Protection

Control of Natural and Acceleratorproduced Radioactive Material (NARM)
 Issue in U.S. because of classification of
material
 Legislation before Congress to give
responsibility to the Nuclear Regulatory
Commission
 Probably not an issue internationally
11 April 2005
5th International High-Energy
Physics Technical Safety Forum
20
Current and Future Issues in
Radiation Protection

Clearance of material that may be slightly
radioactive
 Removal of radioactive materials from
regulatory control
 IAEA Basic Safety Standards and Safety Guide
No. RS-G-1.7 make recommendations
internationally
 NCRP Report No. 141 makes recommendations
for the U.S.
11 April 2005
5th International High-Energy
Physics Technical Safety Forum
21
Current and Future Issues in
Radiation Protection

Future changes in regulations controlling:
 Exposure of workers & public
 ICRP proposal for 2005
 Exposure of ecological species
 ICRP Committee 5
 Decommissioning & disposition of waste
material

11 April 2005
NCRP Annual Meeting 2005
5th International High-Energy
Physics Technical Safety Forum
22
Current and Future Issues in
Radiation Protection

Disposition of low activity radioactive
material
 Risk informed
 Systems approach using Probabilistic Risk or
Performance Analysis
 IAEA Guidance
 NCRP Report No. 139
 Single regulator
 Cost effective disposal, not necessarily recycling
or reuse
11 April 2005
5th International High-Energy
Physics Technical Safety Forum
23
Summary

Radiation dose recommendations for occupational
exposures have evolved as more information is
gathered on the effects of radiation on humans.
 Current recommendations offer protection at a risk
level of a few x 10-4 annually and 1 % lifetime.
 Radiation presents a risk to workers that is similar to
other industrial hazards.
 The control of other hazards might benefit from the
application of principles applied to the control of
radiation hazards.
11 April 2005
5th International High-Energy
Physics Technical Safety Forum
24
Summary

Exposure guidance for people and species
in the environment is not likely to change in
the next few years.
 There is a need for international acceptance
of clearance levels and risk informed
disposition regulations for potentially
radioactive material.
11 April 2005
5th International High-Energy
Physics Technical Safety Forum
25