3. PHYSICS
DIVISION CRYOGENIC SAFETY POLICY AND REQUIREMENTS
In providing for cryogenic safety, hazards shall be
considered as belonging to one of two classes:
1.
Hazards with a potential for personal injury.
2. Hazards
that pose a risk to equipment and/or operation which have no potential for
personal injury.
Hazards of the first class shall be reduced to as low a
level as is reasonably achievable. Hazards of the second class shall be
reduced to as low a level as is cost-effective.
The existing DOE Order concerning cryogenic safety is Order
6430.1A Section 1574, which is primarily directed to liquefaction plants.
This Order nonetheless applies to all cryogenic systems, including those
discussed here. Section 1574 distinguishes two types of systems, namely,
cryogenic storage vessels and cryogenic piping and fittings, with somewhat
different rules and regulations for each class.
Some cryogenic experimental apparatus does not obviously
fall into one class or the other. To clarify this situation, Physics Division
policy in applying DOE Order 6430.1A shall be the following:
If
a system involves the flow of cryogenic fluids through piping or subsystems
contained in a vacuum chamber or vessel, the system shall be considered as a cryogenic
storage vessel if the total volume of cryogenic fluid exceeds 12% of the volume
of the surrounding vacuum vessel (even if the function of the apparatus is not
cryogenic storage). If the cryogenic fluid volume is less than this
amount, the system may be considered to be cryogenic piping and fittings.
3.1 Policy
for New Cryogenic Equipment and Systems
The Physics
Division policy is that new equipment and systems shall:
1. Meet
all applicable federal and state requirements.
2. Be
as safe as practicable.
3.2 Policy
for Existing Equipment and Systems
It should be noted that for existing systems, the applicable
federal and state requirements are, in many instances, those that existed at
the time of procurement or construction of the system in question. The
Physics Division policy for existing equipment and systems is that:
1. Existing
equipment and systems shall meet all applicable federal and state requirements.
2. Existing
equipment and systems must be as safe as practicable.
3. Existing
equipment and systems shall be brought into compliance with current standards
as far as is practicable. Safety aspects of any exception to current
standards shall be reviewed in detail, and further operation shall be
contingent on approval by the Division Director.
3.3 Physics
Division Cryogenic Safety Analysis and Review Requirements
To insure and document compliance with division policy, all
cryogenic equipment and systems shall be subject to a safety review by the
Cryogenic Safety Committee.
3.3.1 Documentation Required for Safety Review
The following documents are required for a safety review of
cryogenic equipment or systems:
1. A description of the system, which shall
include the following:
A. Schematics
and flow diagrams as required to provide a complete and accurate functional
description of the system.
B. Sufficient
information to show that the components, materials, and construction techniques
used are appropriate.
C. Parts
lists with manufacturer�s specifications as appropriate; e.g. pressure
ratings for vessels and plumbing, flow capacity and cracking pressure for
relief valves, etc.
D. Specification
of other, connected systems as may be required for safety analysis.
2. A
description of operating procedures, and of any necessary operator
training. The following elements shall be included:
A. A list of
all valves and ports which have the potential of discharging cold gas or
cryogens to atmosphere (The possibility of such a discharge causing personal
injury should be evaluated).
B. All
required system maintenance in any way impacting safety shall be detailed (e.g.
periodic inspection of pressure relief devices).
C. Emergency
procedures, including methods of evaluating and mitigating any oxygen
deficiency hazard.
3. A
safety analysis detailing the consequences of all significant possible
component failures or operator errors. This shall include:
A. A listing
of all hazards and the steps taken to mitigate them.
B. An
analysis demonstrating the adequacy of pressure relief valve sizing under
worst-case failure conditions.
C. Oxygen
deficiency hazard (ODH) analysis evaluating the class of risk presented under
worst-case failure conditions. Any level of risk higher than Class 0
(refer to Appendix 3) requires that special precaution (refer to Appendix 3
also) will be necessary.