neutralization of vxneutralization of vx - haraburda 2003.pdf · neutralization of vxneutralization...

Neutralization of VXNeutralization of VXUsing Unclassified Information from the Newport project

American Chemical Society MeetingDecember 4, 2003

P d bPresented by:

Scott S. Haraburda, PhD, PEAssistant Project ManagerNewport Chemical Agent Disposal FacilityE-mail: [email protected](765) 245 6097 ( i )

ACS Presentation – December 4, 2003

(765) 245-6097 (voice)(765) 245-5980 (facsimile)

Agenda

N t Ch i l D t (NECD) I f ti

g

• Newport Chemical Depot (NECD) Information

• VX Nerve Agent Information

• Neutralization Process

• Protection Used to Ensure Safety

• Haraburda Project Leadership Rules

• Questions ???Q


Newport Chemical pDepot (NECD)

Information


History 1941 Est. Wabash River Ordnance Works

1943-46 Manufacture RDX Explosives

y

1943-44 Constructed Facility For Heavy Water

1944-46 Heavy Water Productiony

1951-57 Manufacture RDX Explosive

1952-57 Heavy Water Production

1958-61 Built VX Facility

1961-68 Manufactured Chemical Agent VX

i d i 1969 Moratorium on VX Production & Shipment

1968-73 Construction of TNT Facility


1973-74 TNT Production

1993 Lost TNT Mobilization Mission

NECD Mission

Safe and Secure Storage of Agent VXg

Environmental Compliance & Stewardship

Chemical Treaty Compliance Program

Chemical Stockpile Disposal ProgramProgram

Chemical Stockpile Emergency Preparedness Program

Train Soldiers


Maintain Plant Facilities

NECD Features

7,097 Acres – 4,000 Leased for Agriculture g– 1,900 Standing Timber– Wildlife

Security/Fire yDepartment

3 Installation Wells -- 7 Mil Gal ReservoirMil. Gal. Reservoir

Sewage Treatment Plant (3,000 pop.)


Personnel GOCO - Government Owned, Contractor Operated

– Mason & Hanger Corporation, (Day & Zimmermann)Mason & Hanger Corporation, (Day & Zimmermann) Philadelphia, PA.• Fourth-largest Employer in Vermillion County• Operating Contractor Since 1986Operating Contractor Since 1986

Gov’t Staff - 2 Military, 13 DoD Civilians1 IMA– 1 IMA,

– Additional Population:• Newport Chemical Agent Disposal Facility• Chemical Stockpile Defense Force (CSDF)• Chemical Stockpile Defense Force (CSDF)• Tennessee Valley Authority• SAIC


Non-Stockpilep

Demolition of the Former VXProduction Facility

Step IIIAugust 2000 - 2007Steps 0,I,II


p , ,Completed 2002

Newport Community Outreachp y

••Location in Newport CommunityLocation in Newport Community••Integrated NECD/NECDFIntegrated NECD/NECDFOutreach Strategy Outreach Strategy gygy••Speakers’ BureauSpeakers’ Bureau••School ProgramsSchool Programs••Public Availability SessionsPublic Availability Sessions••Public Availability SessionsPublic Availability Sessions••Information RepositoriesInformation Repositories••Information Exchange With Information Exchange With E i D l A iE i D l A iEconomic Development AgenciesEconomic Development Agencies••Presence at Fairs, Festivals and Presence at Fairs, Festivals and ExhibitsExhibits


NECDF HistoryNECDF History

1997 A l d l i h l 1997 – Approval to demonstrate alternative technology –caustic neutralization

1999 – Design/Build/Operate Contract awarded to Parsons1999 Design/Build/Operate Contract awarded to Parsons (Parsons partners include Alion for laboratory operations and Perma-Fix for hydrolysate disposal)

2000 – Construction begins Terrorist attacks of September 11, 2001

11 M 2002 A i iti D i i M d (ADM) 11 May 2002 – Acquisition Decision Memorandum (ADM) signed authorizing the accelerated destruction of the stockpile


p

VX N A tVX Nerve Agent InformationInformation


Nerve Agent Historyg yMost nerve agents belong to a group of chemicals called "organophosphates". The first of these chemicals was made in 1854 and was originally developed to be

d l i d Th fi ( ll d "T b "used to control insects and save crops. The first nerve agent (called "Tabun" or "GA") for military use was made in Germany in 1936. Another nerve agent, "sarin" or "GB," was made in 1938 and "Soman" or "GD" was made in 1944. It appears that these nerve agents were not used by the Germans during World Warappears that these nerve agents were not used by the Germans during World War II. However, it has been estimated that the Germans had stockpiles of tons of both Tabun and Sarin. The United States and Russia continued producing and stockpiling these nerve agents after the War In the 1950's another nerve agentstockpiling these nerve agents after the War. In the 1950 s another nerve agent, "VX", was produced in England.

First Made Lethal Dose Lethal Dose(Year) Breathing (mg*min/m3) Skin (mg)Name (Year) Breathing (mg min/m ) Skin (mg)

Tabun (GA) 1936 150-400 1,000-1,700

Sarin (GB) 1938 75-100 1,000-1,700Soman

Name


Soman (GD) 1944 35-50 50-100

VX 1952 10 6-10

There are several less common nerve agents: GE, GF, VE, VG and VM

VXCAS REGISTRY NUMBERS: 50782-69-9, 51848-47-6, 53800-40-1, 70938-84-0

CHEMICAL NAME: O-ethyl-S-(2-iisopropylaminoethyl) methyl phosphonothiolate

TRADE NAME AND SYNONYMS:Phosphonothioic acid, methyl-, S-(2-bis(1-methylethylamino)ethyl) o-ethyl ester O-ethyl S-(2-diisopropylaminoethyl) methylphosphonothiolate S-2-Diisopropylaminoethyl O-ethyl methylphosphonothioate S-2((2-Diisopropylamino)ethyl) O-ethyl methylphosphonothiolate O-ethyl S-(2-diisopropylaminoethyl) methylphosphonothioate O-ethyl S-(2-diisopropylaminoethyl) methylthiolphosphonoate S-(2-diisopropylaminoethyl) o-ethyl methyl phosphonothiolate Ethyl-S-dimethylaminoethyl methylphosphonothiolate y y y y p pVX EA 1701 TX60

MOLECULAR WEIGHT: 267.38

CHEMICAL FAMILY: Sulfonated organophosphorous compound

FORMULA / CHEMICAL STRUCTURE: C11H26NO2PS / CH3PO(OCH2CH3)S(CH2)2N(CH(CH3)2)2


VXPhysical and Chemical Properties Physical State:

Liquid BOILING POINT : 298 C (568 F) VAPOR PRESSURE (mm Hg): 0 0007 @ 20 CVAPOR PRESSURE (mm Hg): 0.0007 @ 20 C VAPOR DENSITY (AIR=1): 9.2 FREEZING/MELTING POINT : Below -51 C LIQUID DENSITY (g/cc): 1.0083 @ 20 C PERCENTAGE VOLATILE BY VOLUME: 10.5 mg/m3 @ 25 C SOLUBILITY: Slightly soluble in water at room temperature. Soluble in organic solvents.APPEARANCE AND ODOR: Colorless to straw colored liquid & odorless, similar in appearance to

motor oil.FLASHPOINT: 159 C (McCutchan - Young)

VX agent is one of the most dangerous chemicals created. It is used in chemical warfare. In the film "The Rock", it was that green liquid that the terrorists threatened San Francisco Bay with.

VX agent was developed in the Porton Down Chemical Weapons Research Centre, Wiltshire, England in 1952 and its


devastating effects were tested. The British traded the technology of VX with the United States of America for information on thermonuclear weapons.

How VX works

Nerve agents renders the enzyme cholinesterase inactive. This allows thecholinesterase inactive. This allows the neurotransmitter acetylcholine to buildup in the body.

Acetylcholine is produced by the body and functions as a transmitter.

Nerve agents interfere with the signaling system used by the nervous system.

Many organophosphates inhibit acetylcholinesterase, an essential chemical that breaks down the neurotransmitter acetylcholine whichneurotransmitter acetylcholine, which carries nerve signals across gaps between nerve cells.


Source: A FOA Briefing Book on Chemical Weapons: Nerve Agents

Signs and Symptoms for VXg y p Dose / Duration and Route of exposure make a difference

V E (li ht / i iti l) Vapor Exposure (light / initial)– Miosis– Dimming of vision– Lacrimation – excessive tear formationLacrimation excessive tear formation– Rhinorrhea – excessive runny nose– Tightness in chest

Vapor Exposure ( High Concentration )Vapor Exposure ( High Concentration )– Drooling– Coughing– Sweating

Abdominal Cramping

– Uncontrolled diarrhea– Urination– Seizures

Convulsions– Abdominal Cramping– Vomiting– Uncontrolled diarrhea– Urination

– Convulsions– Loss of consciousness– Respiratory failure– Death


Signs and Symptoms for VX( ti d)(continued)

Skin Exposure (Percantaneous)– Redness of areaed ess o a ea– Muscle Twitching– Muscle Spasms– Generalized weakness

Ingestion (Gastrointestinal)– Look for later signs and symptoms of High vapor exposure– Signs and symptoms for ingested VX may take several hours to display

Nerve Agent Antidote– Atropine (administered to block receptor sites of acetylcholine)– 2-PAM Chloride (restores acetylcholinesterase)


Chemical Agent VXProd ction

Four step process

Production

manufactured in campaigns (step 0 I II and III)0,I,II,and III)

• Process Steps 0 - II Produced precursorProduced precursor chemical used in Step III

• Process Step III produced chemical warfare agent VX


warfare agent VX

Accelerated Ton Container Destruction

• Drain containers manually using glove box system

i d i d i• Rinse drained containers, return to appropriate storage

• Neutralize agent in reactorNeutralize agent in reactor vessels

• Ship neutralized by-product (hydrolysate) to off-site commercial treatment facility

• After agent neutralization, complete decontamination of containers and recycle


and recycle

Neutralization Process


Governing Requirements

Source RequirementSource Requirement

Chemical Weapons Convention Irreversible Destruction of Schedule 1 Compounds (i.e., VX and EA2192)

Federal Statute Clean Water Act - No Release of Agent

EPA G id MDL (40 CFR P t 136 A di B)EPA Guidance MDL (40 CFR Part 136 Appendix B)

Indiana Statute Six-Nine Destruction, Low Temperature, Low Pressure, Comparable Facility


“Neutralization”Neutralization Neutralization is a term used by the ChemicalNeutralization is a term used by the Chemical

Demililitarization community indicating that the effects of chemical weapons have been removed (i.e., VX nerve

ff di h VX i li d)agent effects disappear when VX is neutralized)– NOTE: In the Chemistry Community Neutralization only

refers to pH conditions. Water (H2O) is neutral (pH 7). p ( 2 ) (p )A basic solution (pH > 7) can be neutralized to pH 7 by adding acid.

VX can be “neutralized” in several ways. Those tested by the Army include water, Caustic, and Bleach– Caustic Neutralized VX Hydrolysate is approximately


Caustic Neutralized VX Hydrolysate is approximately 10,000 times less toxic than VX

VX “Neutralization”VX Neutralization VX “Neutralization” using water or caustic is a g

Hydrolysis Reaction– “Hydro” from Water indicates adding a water molecule to

VXVX– The NECDF process uses Caustic because it effectively

destroys both VX and EA 2192

Caustic Hydrolysis reactions are also called “Saponification” Reactions (see next slide for example p ( f pof this reaction type)– The 5000 year-old process of making soap is a classic

“saponofication” reaction


saponofication reaction

ACS Presentation – December 4, 2003 Source: waltonfeed.com/old/soap/soapchem.html

NECDF ProcessNECDF Process VX added to hot caustic (194ºF, 20.4 wt.% NaOH)

72 min te feed time ( 5 gpm)– 72 minute feed time (~ 5 gpm)– VX neutralization is “exothermic” [it gives off heat] – slow agent feed minimizes temperature variations – Reactor contents stirred at temperature for 2.5 hours under

Nitrogen (N2) blanket

R l d 100°F d l d Reactors are cooled to 100°F and sampled– 2 samples will be taken from each batch

H d l t i t f d t h ldi t k ithi Hydrolysate is transferred to holding tanks within the reaction area until cleared.


Why’s and What’sWhy s and What s

Why is temperature so important?Why is temperature so important?– Temperature affects the speed of reactions. VX reacts

117 times faster at 194ºF than at 77ºF !Wh thi t t h t it b d– When things get too hot it can be dangerous

• Volatilization rates increase with temperature• Pressure increases (Pressure release valve will open)( p )• Unexpected thermal decomposition products

Why is mixing so important?– VX is insoluble (i.e., doesn’t dissolve) in caustic– In order to react, VX and OH- have to come in contact so

there has to be good mixing !


there has to be good mixing !

More Why’s and What’sMore Why s and What s

f f if * f i i i 1 2If the half-life* of VX in caustic is 1 – 2 seconds, why do we let it react for 2.5 hours?– We want to make sure we get all the VX !We want to make sure we get all the VX !– VX isn’t the only thing we have to get rid of… EA 2192

must be below 20 ppm before hydrolysate leaves the t b ildireactor building.

• The half-life for EA 2192 is about 10 minutes!!• EA 2192 also serves as a process Performance Indicator p

(PI) - if after the 2.5 hours, EA 2192 is still there (above 20 ppm) the reactor mixing isn’t enough to ensure fast VX reaction


ensure fast VX reaction

VX Caustic Neutralization


VX ReactionVX Reaction

Th h lf lif f VX i 20 4% ti t 194°F i The half-life of VX in 20.4% caustic at 194°F is between 1 and 2 seconds – therefore by the end of fill, most of the VX will be gone!of fill, most of the VX will be gone!

The half-life of EA 2192 in 20 4% caustic atThe half-life of EA 2192 in 20.4% caustic at 194°F is estimated to be on the order of 10 minutes. In order to pass hydrolysate clearance criteria, EA 2192 must be below 20 ppm in the hydrolysate (a process control criteria).


VX Neutralization ProcessWater & Water & CausticCaustic

Ton ContainerTon Container NitrogenNitrogen

Chemical Agent Chemical Agent Transfer SystemTransfer System ReactorReactor

HydrolysateHydrolysate

Agent Agent Holding Holding


TankTank

History of Low Level VX Analysis of HydrolysateAnalysis of Hydrolysate

(1994 - 2000)

Scale Method Detection LimitsLaboratory Glass NMR 1 20yReactor < 2 Liters

NMR 1 - 20 ppm

Bench - 2 Liters

Mettler HPLC-MS-MS 100 ppbMettler Calorimeter

HPLC MS MS 100 ppb

Bench - 114 L Reactor

Chloroform Extraction 80 200 b DLeacto

- 12 L Mettlert act o

GC-ITMS 80-200 ppb DL

CAMDS - 100 Gallon Reactor

Hexane - Acid Hexane and C2 MDL Less Than 20 ppb


00 Gallon Reactor ess a 0 ppb

Genesis of Project Speedy Neutralization

Adjunct to additional security measures adopted by the Army following the September 11, 2001, terrorist

tt kattacks– On-site relocation of stockpile– Deployment of National Guard soldiersp y

Goal is to accelerate the disposal of bulk agents– Mustard (HD) at Aberdeen Proving Ground, MD – VX nerve agent at Newport Chemical Depot, IN


What exactly is Hydrolysate

“Hydrolysate” is just the name give to the mixture that results from the caustic hydrolysis of VX

It’s major constituents correspond to the breakdown d t f VX d id l tiproducts of VX and residual caustic:

– Thiolamine, EMPA, MPA, NaOH, ureas– NOTE: Because of the residual NaOH (~ 3.7 wt%), f ( )

hydrolysate is very CORROSIVE! The thiolamine is oxidized by air and makes a disulfide

that floats on top of the caustic along with the ureas, and other organics– The flash point of the upper organic layer is 127ºF


The flash point of the upper organic layer is 127 F

P t ti U d tProtection Used to Ensure SafetyEnsure Safety


Classification of HVAC AreasClassification of HVAC Areas

Category A—toxic process area under negative pressure possible contamination with liquid agent.C t B t i d ti Category B—toxic process area under negative pressure possible contamination with vapor.

Category C—negative pressure subject to vapor Category C—negative pressure subject to vapor contamination.

Category D—ambient air pressure, not contaminated.g y p , Category E—area with filtered air, positive pressure

atmospheres.


VX Air Filtration SystemVX Air Filtration System

P rocess U nder N orm al O perationParticulate Pre-filter H EPA

Six active carbon filter

banks H E PAPre-filter L P r � C

4 A

4 0 i P r eP S n e

A S n e

C n i P 2

r t e4 A

A S n e – t r S t n S r D e l � q S b 2 i r

– t r S t n S r D e � e A 0 P n 2 C e– t r S t n S r D e � e A 0 P n 2 C

ACS Presentation – December 4, 20035/27 /2002T R-LP-O SHA -1, Rev 0

30

12/6/2002 47

Decontamination Levels -E i tEquipment

1 X – Item may have been decontaminated but it still has agent presentit still has agent present.

3X – Item has been surfaced deconned bysurfaced deconned by approved procedures.

5X – Item deconned and can be sold to the public.


Safeguarding PersonnelSafeguarding Personnel

All personnel entering the Limited Area will be issued M40-series mask and 3 Mark 1 Kits

All clothing will be changed at the beginning g g g gand end of the work shift for all agent workers that will enter the Exclusion Area.

Eating, drinking, chewing and smoking within the Limited Area is prohibited unless specifically approved


specifically approved.

Personnel Protective Clothing L l ALevel Ata

ry

HA

Mili

t

OSH

M

Demilitarization Personnel Ensemble Military attire for chemical agent

work

Highest level of protection

High potential for splash or t ki h d


work. Provides the most protection against

chemical or biological hazards.

exposure to skin hazards

IDLH or unknown environment

Personnel Protective Clothing L l BLevel Bta

ry

HA

Mili

t

OSH

Provide the next best protection against chemicals

Highest level of respiratory and some degree of skin protection

P f


Presence of vapor or gas

Direct contact with contaminant unlikely

Personnel Protective Clothing L l CLevel Cta

ry

HA

Mili

t

OSH

Level C Protective Clothing Next best protection against chemical Uses the M40 mask

Used when contaminant is known

Level of contaminant is measured


Uses the M40 mask Criteria for wearing APR is met

Severe skin hazard unlikely

Personnel Protective Clothing L l DLevel Dta

ry

HA

Mili

t

OSH

Level D Protective Clothing Least amount of protection against

chemical

Minimal protection from physical hazards

Hazardous free atmosphere


Uses the M40 respirator slungHazardous free atmosphere

Work precludes potential for exposure to hazardous substances

Personnel Protective Clothing L l D Oth V i tiLevel D – Other Variations

Also Class D protective clothing M40 respirator slung Least protection against chemicals

Also Class D protective clothing M40 respirator slung

T i ll b i it t i t


Least protection against chemicals Primarily used in laboratory

situations

Typically worn by visitor, transient workers, or non-agent workers.

Monitoring Methods

Two methods will be utilized in the VX air monitoring system

A l ti it i t i i– A near real-time monitoring system is primary analytical method used for all workplaces (MINICAMS)(MINICAMS)

– DAAMS a manual method used for integrated air sampling and confirmation analysis.p g y

Sulfur monitors will be used for Hydrolosate


Air Monitoring Concept

MINICAMS DAAMS

Outside and Inside the Work Area Structure (Secondary Containment)

Support NRT monitoringStructure (Secondary Containment)

– Utilize MINICAMS cycling every 380 seconds (180 sampling/200 analysis).

– MINICAMS alarm will be generated on a response ≥0.7 TWA.

Confirmation DAAMS sampling will be initiated on MINICAMS work area alarms.C fi ti DAAMS ill b l d


a response ≥0.7 TWA. Inside the Primary Containment on

individual sample basis, not continually.

Confirmation DAAMS will be sampled to obtain a 12L sample.

H b d ’ P j tHaraburda’s ProjectLeadership RulesLeadership Rules


Haraburda’s ProjectL d hi R lLeadership Rules

Projecto Cannot have all three: cheaper, better, faster.

Communicationo Consensus usually results in “weakest

d i ” d i io Accomplishing the task is more important than the tool used.

o Plan and sacrifice now for the sake of the future.o A poor plan implemented is much better than the best

plan that is not implemented

denominator” decisions.o Meetings should be short, infrequent, and value-

added.o Communicate the results, both the good with the

bad.plan that is not implemented.

DataM i h ld b d if l i (f

o Sell the good statements, not the bad, even though it is easier for the bad ones.

Problem Solvingo Toda ’s problems come from esterda ’so Metrics should be used if one plans to use it (for

decisions).o Understand the source of the data.o Meaningless goals, even if easily obtained, should not

be used.

o Today’s problems come from yesterday’s solutions.

o The cure can be worse than the disease.o Dominate technology – do not let it dominate

you.o Challenge Your Assumptions (CYA).

Peopleo A project begins, ends, sinks, and swims with people.o Reward good performers; coach or remove bad ones

o Solve the problems, not the symptoms.

Decision-Makingo Doing the right thing is better than doing things

right


o Reward good performers; coach or remove bad ones.o Train your successor.o Do not try to please everyone, someone will not like it.

right.o Better is the enemy of “good enough.”o Resources mean nothing if not used.o If it “ain’t broke,” either maintain or improve it.

Q ti ????Questions ????


R A P H YI O GB R A P H YI O GBSCOTT S. HARABURDA, PhD, PE

Lieutenant Colonel, US Army

Lieutenant Colonel Scott S. Haraburda has given over twenty-two years to thepeople of the United States as both an Officer and an Enlisted Soldier in theUnited States Army. As an army reserve officer, he is currently the commanderof the 472nd Chemical Battalion. His other reserve assignments includeengineering and contingency contracting positions within 8th US Army, researchand development positions for Army Material Command, and admission related

iti f th U it d St t Milit A d t W t P i t Li t tpositions for the United States Military Academy at West Point. LieutenantColonel Haraburda served on active duty for 9 years, with assignments inadvising about chemical warfare at Fort Hood, Texas and teaching chemistry atWest Point, New York. In 1991, Lieutenant Colonel Haraburda was one of threeofficers nominated by the Army to become an Astronaut Candidate for NASA.

In addition to being both a branch qualified chemical and engineer officer,Lieutenant Colonel Haraburda is a member of the Army Acquisition Corps

He earned a BS in chemistry in 1983 from Central Michigan University(CMU), a MS in chemical engineering in 1990 and a PhD in chemicalengineering in 2001 from Michigan State University (MSU). As aDistinguished Military Graduate of the ROTC program at CMU he receivedLieutenant Colonel Haraburda is a member of the Army Acquisition Corps

(AAC). As part of his training within the AAC, he has completed several dozencourses from the Defense Acquisition University. With his training andexperience in the acquisition field, Lieutenant Colonel Haraburda hascertifications in the following fields: 1) Program Management; 2) Contracting; 3)Systems Planning, Research, Development and Engineering; 4) InformationTechnology; and 5) Test & Evaluation Engineering. Additionally, he successfullycompleted the Department of Defense Chief Information Officer Certificate

Distinguished Military Graduate of the ROTC program at CMU, he receivedhis commission as an army officer in 1983. He is also a graduate of theChemical Officer Basic and Advanced Courses, the Engineer Captains CareerCourse, the Combined Arms Services Staff School, the Associate LogisticsExecutive Officers Course, the US Army Command and General Staff College,the US Naval Command and Staff College, the Defense Strategy Course at theUS Army War College, and the US Air War College.

p pprogram from the Information Resource Management College.

In his civilian life, Dr. Haraburda worked at Bayer Corporation for 4 years inPennsylvania and West Virginia, as a process engineer. In addition to Bayer, heworked at G.E. Plastics for 4 years as a production engineer in Mount Vernon,Indiana. Since June 2000, Dr. Haraburda has been working as a civilian for theUS Army as the assistant project manager for the Newport Chemical AgentDisposal Facility in Indiana where several tons of VX nerve agent will be

For his exemplary accomplishments and dedication, Lieutenant ColonelHaraburda has received the Army Commendation Medal with three Oak LeafClusters, Army Achievement Medal with three Oak Leaf Clusters, ArmyReserve Component Achievement Medal with two Oak Leaf Clusters, NationalDefense Service Medal, Armed Forces Reserve Medal with Bronze Hourglass,Army Service Ribbon, Army Reserve Components Overseas Training Ribbonwith Numeral Three, Air Assault Badge, and German Armed ForcesP fi i B d i B


Disposal Facility in Indiana where several tons of VX nerve-agent will bedestroyed. He is a registered Professional Engineer (PE) in the State of Indiana.Dr. Haraburda wrote 11 technical articles, wrote 6 management articles, wrote 1chemical engineering handbook, and presented 7 international electric propulsionconference articles. He has also filed 10 patent applications.

Proficiency Badge in Bronze.

neutralization of vxneutralization of vx - haraburda 2003.pdf · neutralization of vxneutralization...

Documents