E4150 Facility Protection

8/2/2019 E4150 Facility Protection

1/39

Multi-layer Protection Strategy

for Manufacturing Facilities

Vasilis FthenakisNational Photovoltaic EH&S Assistance Center

Brookhaven National Laboratory

SSA 2001 Annual Symposium

New Orleans, LA


2/39

National Photovoltaic EH&S

Assistance Center www.pv.bnl.go

Preserve safe & environmentally friendly facilities

(S&E audits, SAR, HAZOP, FTA)

Identify/characterize potential EH&S hazards before full-scale

commercialization of new technologies, processes&

materials (Si, x-Si, a-Si, CdTe, CIS, CGS, GaAs, ZnP)

End-of-Life PV module recycling feasibility (with DOE-SBIR)

Pb-free solder technology transfer

Toxicology of new materials e.g., CdTe, CIS, CGS, (with NIEHS) Integrated energy-environmental-economic market penetration &

CO2 reduction forecasts (MARKAL model)


3/39

Sample of Hazardous Materials

Used in Manufacturing

Material OSHA-PEL

(ppm)

ACGIH-STEL(ppm)

NIOSH-IDLH

(ppm)

AIHA-ERPG-2

(ppm)

OSHA-PSM-TQ

(lb)

Comments

Arsine 0.05 3 3 - 100 Highly toxic,potential carcinogen

Arsenic 0.01 mg/m3

(inorganic)

5 mg/m3 Highly toxic, potentialcarcinogen

Cadmium

compounds

0.005 mg/m3

(fumes)

- - NA Potential carcinogen

Carbon

tetrachloride

10 25 200 100 Toxic, potent greenhouse gas

Silane 5 - - - 10,000 High fire & explosion hazard

Diborane 0.1 - 15 1 Highly toxic

Boron

Trifluoride

1 25 250 Toxic

Hydrogen - - - 10,000 Fire hazard

Hydrogen

fluoride

3 30 20 1,000 Noxious, corrosive

Hydrogen

selenide

0.05 2 150 Highly toxic, flammable

Hydrogen

sulfide

10 15 - 30 1,500 Toxic, flammable

Phosphine 0.3 1 50 - Highly toxic, flammable


4/39

Elements of EH&S Hazard Assessment

Process &MaterialOptions

Exposure &ConsequenceAnalyses

Evaluation ofPrevention &MitigationStrategies

Cost-BenefitAnalysis

BiomedicalResearch

Identificationof Physical &ChemicalHazards

Dose-ResponseAssessment

Process LevelScreening ofHazards

R &D Hazard Hazard HazardIdentification Characterization Management


5/39

Choice of TechnologyProcess & Materials

Material Utilization

Inherently Safer Options

Safe Delivery, Dilute Mixtures,SDS, High Utilization,Reduced Inventories

Detection, O&M Procedures,Training, SRA, HAZOP, FTA

Accident InitiatingEvent

Emergency Scrubbing

External Release

HAZARD DEVELOPMENT PREVENTION/MITIGATION LAYERS

Contained Release

Human Exposure

Flow Restrictors, Auto-shut offDouble Containment

Remote Site, SeparationZones , Emergency Planning


6/39

Defense in Depth


7/39

Selection of Technology,

Processes and Materials

Technologies and processes that do not require the use of

large quantities of hazardous materials; especially

important for new technologies

Consider:

Type & form of material used

Utilization rate

Process emissions

Life-cycle

If a hazardous material must be used, then try safer forms

and minimum quantities.


8/39

Safer Material Utilization

Substitution (use safer materials or environmentally more

benign ones)

Attenuation (use a safer, less mobile form of a hazardous

material)

Intensification (reduce the quantity of a hazardous material

in process and storage)

Dilution (reduce its concentration)

Point-of-use generationAlternatives need careful evaluation


9/39

Material Substitution Examples

Wet etching with plasma etching

Wet wafer cleaning with gas-phase cleaning

Silane (in epitaxial Si and Si3N4 deposition) with

organosilanes and chlorosilanes AsH3 & PH3, with TBA & TBP

AsH3, PH3 & H2Se, with solid As, P, & Se compounds


10/39

Safer Material Forms

Subatmospheric pressure gas sources (AsH3, PH3, BF3)

VAC -Internally pressure regulated sources (SiH4)

Twofold benefit; it reduces the probability for an explosion

and the overpressure resulting from one

For hazardous solid materials (e.g., Cd compounds)

using the material in pelleted form instead of a fine

(respirable size) powder, reduces the severity ofexposure.


11/39

Dilution

Wafer cleaning processes that do not require

concentrated chemical solutions

Diluted inorganic hydrides reduce consequences of leaks

For toxic gases (e.g., PH3, B2H6), is a trade-off betweenfrequency and maximum consequences of an incident.

For explosive gases, the benefit of dilution is twofold; it

reduces the probability for an explosion and the

overpressure resulting from one. Productivity issues


12/39

Reduced Quantities on Site

High rate of material use & strict control of inventories.

Deposition processes that use materials more efficiently:

(Hot-wire deposition vs. plasma-discharge deposition in a-Si;Electrodeposition vs. spray pyrolysis in CdTe and CdS deposition).

Higher material utilization rates offers safety advantages and lower

costs; processes with low efficiency will have to be improved or

unused materials be captured, purified, and reused.


13/39

Mini-Bulk or Bulk Deliveries

vs. Cylinder Deliveries

Bulk gas delivery advantages:

Better purity, lower cost, reduced probability of a leak.

Disadvantages:

Much greater potential consequences The safety issue is controversial

A decision is facility specific;

it depends on facility location and size.

Standards/Guides applicable to bulk SiH4NFPA 318, FM, SEMI, CGA


14/39




Safe Delivery, Dilute Mixtures,High Utilization, ReducedInventories

Detection, O&M Procedures,Training, SRA, HAZOP, FTA

Accident InitiatingEvent

Emergency Scrubbing

External Release


Contained Release

Human Exposure

Flow Restrictors, Auto-shut offDouble Containment

Remote Site, SeparationZones , Emergency Planning


15/39

Prevention of Initiating Events

Once specific materials and systems have been selected, strategies to

prevent accident-initiating events need to be evaluated & implemented

US facilities that handle listed hazardous chemicals in quantities above certain

thresholds are required to comply withOSHA Process Safety Rule (PSM)

EPA Risk Management Program (RMP).

Some Listed materials:

AsH3, BCl3, BF3,B2H6, H2Se, H2S, HF, NH3 PH3, SiH2Cl2, H2, SiH4, SiHCl3


16/39

Components of the EPA -RMP

1. Hazard Assessment Analyze transients

Review documentation of past releases

Identify worst-case & likely release scenarios

Estimate maximum impact zones

2. Accident Prevention Safety precautions and management systems

Operating procedures.

Employee safety training

Process Hazard Analysis

Safety audits Incident investigation & report Control and mitigation systems

3. Emergency Preparedness and Response


17/39

Prevention of Initiating Events

Be Proactive!

Conduct Process Hazard Analysis (PHA) even when it is not

required.

PHA must be formal & rigorous.

PHA focus on equipment, instrumentation, utilities, human

action, external factors that may impact a process & cause an

accident initiating event.

Example: SAR conducted proactively as a result of a self-

appraisal at NREL


18/39

Safety Analysis Review (SAR)

Reviewed operations

Identified 30 potential accident-initiating events

Characterized risks

Implemented administrative and engineering controls to

ensure safe operation, e.g.

Control systems to avoid cross-contamination, elimination of

single-point failures, safeguards against process deviations and

monitoring systems.

Safe operating & maintenance procedures & training.


19/39

Risk Assessment Matrix

PROBABILITY

CONSEQUENCE

AFrequent

BReasonblProbable

COccasional

DRemote

EExtremely

Remote

FImpossible

ICatastrophic

HIGH RISK

II

Critical

LOW

IIIMarginal

MODERATE

IVNegligible

ROUTINE


20/39

Risk Assessment Matrix

Event probability classificationA: Frequent (>1.0). Likely to occur many times during the life cycle of the system

(test/activity/operation).B: Reasonably probably (0.1-1.0). Likely to occur some time during the life cycle of the system.C: Occasional (0.01-0.1). Likely to occur some time during the life cycle of the system.D: Remote (10-4-10-2). Not likely to occur in the life cycle of the system, but possible.E: Extremely remote (10-6-10-4). Probability of occurrence cannot be distinguished from zero.F: Impossible ($1 million). May cause death or system loss.II: Critical ($100,000-$1 million). May cause severe injury or occupational illness or minor systemdamage.

III: Marginal ($10,000-$100,000). May cause minor injury, occupation illness, or system damage.IV: Negligible (


21/39

Prevention Layers Failed!


22/39

Prevention/Minimization

of Releases

Implement safety options to suppress a hazard when an accident-initiating event occurs

Prevention options to enhance the safety of compressed-gas cylinde

systems:

a) Continuous monitoring, early detectionb) System integrity, fail-proof design

c) Outside storage or indoors explosion-proof banker

d) Remotely operated cylinder valves

e) Automated purgingf) Flow restrictors

g) Double containment

e) Redundancy of critical systems


23/39

System Integrity

Operational hazards are greatly reduced by certain

features that improve the system's integrity, e.g.,

properly designed, constructed, and vented enclosures,

welded piping joints,

ventilation system back-up,

alarms and interlocks for process chambers.


24/39

Outside Storage

Outside storage bunkers for toxic and pyrophoric

gases reduce occupational risks associated with

accidental releases.


25/39

Indoors Bunkers

Silane cylinders can be kept indoors in explosion-

proof bunkers (with relief through the ceiling);

however, this is an expensive option.


26/39

Remote Operation

Remotely operated cylinder valves enhance safety

by separating workers from hazards and allowing

for remote shutdown in an emergency.


27/39

Automated Purging

Manual purging is demanding on the operator.

Automated purge systems reduce actions needed

to complete a purge procedure, and reducepotential for human errors.

C ti T i G


28/39

Continuous Toxic Gas

Monitoring Systems

Integrate toxic-gas detection into gas-handling

systems and process tools for early warning and

source & process shut down

Set audible and visible alarms at 1/2 TLV


29/39

Flow Restrictors

Flow-restricting orifices (RFO) in cylinder valves

for highly toxic and pyrophoric gases (e.g., AsH3,

PH3, SiH4).

RFO can reduce the flow out of an open cylinder-

valve up to 100 times; they provide superb passive

flow-reduction.


30/39

Double Containment

Double co-axial distribution lines and raceways.

Double-wall storage.

Secondary enclosures to contain toxic emissions and

divert to pollution-control equipment.


31/39


32/39

Redundancy in Critical Systems

If a hazard analysis identifies accidents that can be caused by the

failure of a single component, redundant components should be

installed

Examples of critical components:

Flow-regulators, valves, exhaust fans, pumps, compressors.

Redundant systems must be completely independent

Examine conditions which may adversely affect a given layer of

defense at the same time that they produce a safety challenge to

that layer

(Such conditions in complex systems can be studied with Fault Tree

Analysis)


33/39

Prevention and Minimization


34/39

Prevention and Minimization

of Human Exposures

Remote location, exclusion zones

Early warning systems

Emergency preparedness and response programs

Medical preparedness

Multi-Layer Protection for Occupational Safety


35/39



Medical SurveillanceBiomonitoring)Medical Treatment

Multi-Layer Protection for Occupational Safety


Employee Exposure

OSHA/Industry Employee ProtectionPrograms, e.g., air monitoring,ventilation, SOP

Safer Delivery, SDS, High Utilization,Reduced Pressure


Consequences


36/39

CONCLUSION

Accidental releases of hazardous gases and vapors can cause

occupational hazards.

Prevent and minimize accidental releases of hazardous gases by

choosing safer technologies, processes, and materials, using material

more efficiently and in safer forms.

Use safety systems and procedures to reduce risks that could not be

avoided with process and material selections.

A systematic approach assists management to minimize EH&S risks

We are all partners in EH&S !


37/39

We are all partners in EH&S !Working together means winning togethe

www.pv.bnl.go


38/39

Point-of-use Generation

Point-of-use generation of hazardous materials reduces

the hazards of both transportation and storage on-site.

e.g., Bell Labs on-demand arsine generators give betterpurity than compressed-gas cylinders


39/39

Risk Analysis Results

Probability Conse uence RiskTransient description I ER R O RP F N M C CA R L M HIntralaboratory transportation accident * * *Missing washer in HCI or H2Se cylinder * * *Forgetting washer/gasket in gasketed gasconnection

* * *

Attempts to open sticky cylinder capToxic/pyrophoric liquid bubbler put inbackwards

Toxic/pyrophoric liquid bubbler leakoutside delivery systemLeak of air in vacuum pumpFaulty seals connecting reactor vessel tosystem

Rupture of quartz reactor vesselHydrogen leak in purifierLoss of process control and simultaneous

failure of scram unit, exhaust scrubber, orcylinder valveHigh winds and tornadoes

Documents

E4150 Facility Protection