apollo experience report processing of lunar samples in a sterile nitrogen atmosphere

8/8/2019 Apollo Experience Report Processing of Lunar Samples in a Sterile Nitrogen Atmosphere

1/17

- -

z

N A S A T E C H N IC A L N O T E N A S A T N D-6858.&- / -- Im- 0-0 -Im 0-= E

00 I+=w mYn LOAN COPY RETURhw-fn -AFWL (DOUL) fnm+ KlRTLAND AFB. N. r u m-Q - 2-m4z

APOLLO EXPERIENCE REPORT -PROCESSING OF LUNAR SAMPLES INA STERILE NITROGEN ATMOSPHEREby Thomas M . McPhersonManned Spacecrafi CenterHouston, Texas 77058N A T I O N A L A E R ON A U TI C S A N D S PA CE A D M I N I S T R A T I O N W A S H I N G T O N , D. C. JUNE 1 9 7 2


2/17

--

--

.- -..1 . Report No. 2. Government Accession NO.NASA TN D-6858

2. Sponsoring Agency Name and AddressN a t i o n a l A e r o n a u t i c s a n d S p a c e A d m i n i s t r a t i o nWashington , D. C. 205465 Supplementary Notes--

TECH LIBRARY KAFB, NM

3. Recipient's Catalog No.

5. Reoort DateJune 19726. Performing Organization Code

8. Performing Organization Report No,MSC S-332

10. Work Unit No.076-00-00-00-7211 . Contract or Grant NO.

13. Type of Report and Period CoveredT e c h n i c a l N o t e14 . Sponsoring Agency Code

The MSC Dire cto r has waived the use of the In terna t ion al Sys te m of Uni ts (SI) f o r t h i sTechn ica l No te , b e c a u s e , i n his j udgmen t, t he u s e of SI u n i t s w o ul d i m p a i r t h e u s e f u l n e s s of t he r e p o r t o r r e s u l t i n e x c e ss i v e c o s t ._ _ .- 6 AbstractA s t e r i l e n i t r o g e r, a t m o s p h e r e p r o c e s s i n g c a b i n e t l i n e w a s i n s t a l l e d i n t h e L u n a r R e c e i v in gL a b o r a t o r y t o p r o c e s s r e t u r n e d l u n a r s a m p l e s w i th m i n i m u m o r g a n i c c o n t a m i n a ti o n . D e s i g na n d o p e r a t i o n of t h e c a b i n e t l i n e w e r e c o m p l i c a t e d by t h e r e q u i r e m e n t f o r b i o l o g ic a l s t e r i l i z a t i o n a n d i s o l a ti o n , w h i c h n e c e s s i t a t e d e x t e n s i v e f i l tr a t i o n , l e a k -c h e c k i n g , a n d s y s t e m s t e r i l i z a t io n b e f o r e u s e . I n d u s t r i a l t e c h n iq u e s w e r e a p p l ie d t o l u n a r - s a m p l e p r o c e s s i n g t o m e e tr e q u i r e m e n t s f o r t i m e - c r i t i c a l e x p e r i m e n t s w h i l e h a n d l i n g a l a rg e f low of s a m p l es .

18. Distlibution Statement

. ~ _ _ - .. ~ ; of Pages 22. Price19. Security Classif. (of this report) 20. Security Ciassif. ( : this page) 1 21 . I $3.00one None- I ? ~ I I .* For s a l e by t h e Na t i o n a l Te ch n i ca l In fo r ma t i o n S e rv i ce , Springfield, Virginia 22151

...


3/17

APOLLO EXPE R l ENCE REPORTP R O C E S S I N G OF L U N A R S A M P L E S I N A

S T ER IL E N I T R O G E N A T M O S P H E R EBy T h o m a s M. M c P h e r s o nM a n n e d S p a c e cr a f t C s n t e r

S U M M A R Y

A st er ile nitrogen atmosphere proces sing cabinet line was installed in the LunarReceiving Laboratory to pr oce ss sample mate rial returne d fro m Apollo missions . Themajo r prob lems concerning the installation and operation of the cabinet line were indesign and fabrica tion, leak-checking and steriliz ation, installation and operati on of theenvironmental monitors, and operational organization and sample control.Design and fabrication experience showed that welded se am s (rat her than gasketed), removable par ts , carefu l welding and window-cutting, and unitary constructionwere important considerations in construction of the c la ss I11 biological cabinetry . Thematerials used for cabinet fabrication w e r e found to requ ire lubrication, and the lubricant had to undergo radiation counting. Viton w a s substituted for Teflon as the materialfor valve diaphragms, and tempered gla ss w a s substituted for Lexan as the material forwindows.Concerning leak-checking and sterilization, it w a s found important to avoid indiscrim inate use of halogens in prelimina ry leak checks. Theref ore, leak-testing alwaysbegan with a gaseous-nitrogen pressure-decay test before a halogen or helium leakcheck was made. All cabinets and piping sys tems wer e overste rilized to prevent backcontamination. Ethylene oxide diluted with Freon was used as the steriliz ing agent.Experience showed that environmental monitoring should be integrated into thedesign of the cabinet line rat he r than added af te r projec t completion. It was a lso foundadvantageous to incorpo rate c erta in changeout proced ures in equipment design to pre

vent shutdown or contamination of the cabinet line should a sensor fail. Oxygen-anal yze r sy st em s should be final-leak-checked by using bottled oxygen as a t racer gasto detec t concentrat ions of oxygen less than 100 pa rt s p er million.Regarding operational organization and sample controls, an assembly -line typeof sys tem was found to be the best method for proc essing lunar sample material. Twosimulations were held to determ ine the best dis tribution of duties and the line s of authority among cabinet line operational personnel.


4/17

1 1 1 - 1 . ,. ......-.......

I N T R O D U C T I O NThe s ter ile nitrogen atmosphere proce ssing (SNAP) cabinet line was installed inthe Lunar Receiving Laboratory (LRL) after the Apollo 1 2 mission to proce ss m ateria lreturned in sealed Apollo lunar-sample ret urn containers (ALSRC) fro m later Apollomissio ns. The samp les retu rned to this cabinet line had not been exposed to the environm ent of th e lunar module o r command and ser vic e module cabin; therefore, everyeffort was made to design, fabricate, install, and operate the SNAP line in such a wayas to minimize the organic ma teri als that could contaminate the s amples during processing. In addition, the thre at of unknown bacteriological ag ents in the retur ned s amplemat eria l required that the cabinet line and all the auxiliary syst ems be opera ted underthe requ ireme nts of cla ss I11 bacteriological enclosures. These requirements entailedextensive filtration, leak-checking, and establishing and maintaining complete ster ili

zation of the cabinet line during sam ple proce ssing and tra ns fe r operations. Fur the rmore , anticipation of a large amount of sample ret urn and a t ight schedule fo r sampleprocessing to support time-c ritical experiments in other LRL laboratories necessitatedan organization and sample contr ols ca pable of handling a la rg e flow of s am pl es with nomista kes of identity o r confused processing history. This accomplishment is describedin the following secti ons.

C A B I N E T A N D E Q U IP M E NT D E S IG N A N D F A B R I C A T I O NCare ful choice of mat eri als and a n understanding of spe cial design requ ireme ntscan ass ur e cabinet lines relatively free of organic mat erials and facilitate cleaning andsterilization.The basic materi als approved for the

cons tructi on of t he SNAP cabinet line(fig. 1) to minimize org anic contaminationwere stain less steel, aluminum, Teflon,and Viton, in or de r of acceptab ility. Theoretically, the se materials wer e ideal; inpract ice, some compromises had to bemade. For example, lubricants wererequ ired to prevent galling of metal su rfac es in screw threads. Powdered molybdenum disulfide (MDS)mixed with isopropylalcohol and distilled water was used andapplied with a n artist's brush. CommercialMDS mixtures were not acceptable becausethe re sin binder in most was highly o rganic.Because some of the lunar -sam ple m ater ialto be exposed in the cabinets w a s to becounted for radiation, the batch es of MDSused t o compound the lubrica nt al so had tobe counted. The rea son was that, beforethe SNAP line wa s designed , it had beendiscovered during other LRL operations

u n i t s 1M1K e y :1. A i r l o c k

2. U n p a c k i n q a n d A L S R C s t e r i l i z a t i o n3. A L S R C f i n a l d r y i n g4 . A L SR C o w n i n a a n d s i e v i na S t e r i iz e r5 . S a m p le i n v e n t i r y

5 A . S a m p l e p h o t o g r a p h y6 . S a m p l e m o d e l i n g and d e s c r i p t i o n7 . S a m p l e s t o ra g e

7 A . S a m p l e d i s p l a y8. S a m p l e s t o ra g e9. C h i p p i n g a n d p a c k a g i ng

Figure 1. - Funct ional drawing of SNAPline.

2


5/17

that s ome lots of MDS contained enough radioactive ma teri al to int erf ere with sensitivemeasu remen ts of r esid ual radioactivity in the lunar samp les.Cabinet windows also requi red co mprom ises. Initially, the cabinet windows weremade of Lexan, a polycarbonate pla stic organically and radiologically ine rt. Unfortunately, Lexan has an extremely soft surfac e and is not as t ransparent as glass. Also,

many imperfections (bubbles, etc. ) were noted in the larg e sheets use d f or windows.The Lexan windows were not satisfa ctory; after short use, the plast ic surfaces werecovered with small scratche s. Attempts to polish out these sc ratc hes were unsuccessful; most polishing materials only scra tched the surface more. Those materia ls thatsuccessfully removed the s cra tche s required excessive manpower and expensive materials, and the improvement was only temporary . The grayis h haze, or lack of tr an sparency of Lexan, al so prevented high-resolution photography of s am pl es through thewindows. For this reaso n, those windows through which the samp le photographs wereto be taken were exchanged fo r tempered gl ass before the first lunar samples wereproc es sed in the SNAP line. Another annoying charac te ris tic of Lexan was noted dur ing the process ing of fine-gra ined Apollo 14 lunar sampl es. The plastic was found tocollect a strong stat ic charge; in a sho rt time , the cabinet windows were covered withdust par ticle s, and attempt s to wipe the windows clean only caused smudges. Becausethe tem pered gl as s windows did not exhibit this cha racte ri sti c, most of the remaining(i.e . , nonphotographic) Lexan windows were a lso exchanged fo r tempere d gla ss, sa mple s of which were made availabl e fo r chemi cal testing and radiation counting.

Le ss significant compromi ses we re made in the introduction of moisture-monitorse ns or s (s ma ll devices that contain minute quan tities of gold and epoxy) and in elec trica l feedthroughs. The feedthroughs ar e vacuum-compatible units with a stainless steelbody and glass in sert, and come close st to meeting the organic requirements as off-the-shelf items.Compromises were a lso made in three featu res external to the cabinets. Mostvalves in the SNAP line a r e commercially available diaphragm-type units. Teflon

diaphragms were originally specified and installed, but through-leakage resulting fromthe hardn ess and cold-flow ch ar ac te ris tic s of Teflon proved to be a major problem. Thevalve diaphragms were replaced with Viton, a softer ma terial that was less desirableorganically but sealed much bet ter. The flowm eters in the gaseous-nitrogen supplyline we re acr ylic plasti c. These units wer e the only ones available on the tight scheduleunder which the SNAP line was constructed. These flowmete rs proved to be a majorso ur ce of leaks and were eventually potted with epoxy. Units with sta inl es s st ee l bodies,Viton O-rings, and Pyre x tubes ar e commercially available and should be considered innew designs. The exhaust-line bac k-p res sur e regulators , which wer e com mer cia lquality iron /ste el ite ms, wer e another sou rc e of leaks. These units were a lso sealedwith epoxy, but, in this c as e, the problem of organic contamination was not c rit ic albecause the regula tors were on the downstream sid e of the cabinets.Sever al ite ms should be consider ed in the design of cabinets intended fo r minimumorganic contamination and sterilization . All intern al surf ace s of the cabinets should befinished to an American Standards Association number 4 satin finish o r better. Thispolished finish was nec ess ary in the LRL because the cabinets were chemically cleanedand sterilize d before each mission, and a smooth finish facilitated these operations.To aid cleaning, a 1-inch minimum rad ius on all co rn er s should be specified. Crack sand crev ices should be avoided whenever possible because such openings ar e tra ps fo r

3


6/17

organ ic and bacteriological contamination during construction and are essentially impossible to clean and ster ilize by norm al methods afterwa rds. Also, cr ack s and crevices are so ur ces of leaks that can be difficult to locate and re pa ir. Generally, weldedseams are pr efe rr ed over gasketed se ams . An ideal solution to the problem of cr ack sand c rev ices would be t o weld together into one unit all the cabinets that comp rise aline. Becaus e of limitation s imposed by transportation and installation requirements,this unitary construction is extrem ely difficult to achieve in practic e. Nevertheless,every effort should be made to have the manufacturer weld cabinets into units insofaras those limitations will allow. A portion of the SNAP cabinet line welded togethe r as aunit during manufacture is much e as ier to clean and leak-check than gasketed sections.A removable pla te containing piping feedthroughs should al so be included in the designof each cabinet. This ite m is minor, but one that can prevent a major p rogram difficulty if an additional piping feedthrough is required after the cabinet has been installed,It is relatively easy to remove a plate, take it to the shop, cut a hole and weld the newpipe in place, then leak-check, clean, and rein stal l the plate in the cabinet. The sam etask is much more difficult to perform on the cabinet itself while trying to keep thecabinet leaktight, undamaged, and clean. The locations of the pipe-penetration panelson the SNAP line a r e shown in figur e 1.In contracting to fabric ate cabinets o r in fabricating cabinets in-house, it shouldbe re mem ber ed that manufacturing quality is most importan t if no seala nts such aspolysulfide or epoxy are to be used (a require ment f or minimum organic contamination).The SNAP cabinets were constructed and asse mbled with sufficient quality to meet thisrequirement. In some cas es, the piping to and fro m the cabinets required s ma llamounts of sealan ts, but experience ha s shown that sea lant s in thes e ar e as could nowbe eliminated if fur ther improvements in contamination level wer e re quired.Experience ha s shown two cr iti ca l ar e as in cabinet fabrication in which knowledgeand high-quality workmanship a r e mandatory: in the cutting and formin g of the windowopenings and in welding. Cutting and for ming a window opening s o that the sides ar eflat and parallel can be extremely difficult unless the manufacturer has prop er equip

ment and knowledge fo r working with thin sta inle ss ste el s hee ts. The la rg er the window,the m or e difficult the task is . A nonflat, nonpa rallel window fr ame is impossible toseal. A Viton gasket cannot be co mpr ess ed like neoprene; therefo re, a fla t windowfram e is mandatory. A nonparallel window fr am e can easily crac k safety glass duringtorquing and, in some cases , can cause st re ss es that wil l eventually shatter temperedglass. It is possible to rewor k unacceptable window fr am es by using hydraulic jac ksand pre sses , but this process is a long and tedious operation. The welding opera tion iscr iti ca l because heat-induced warpage can affect sealing. A competent manufacturerwill avoid this warpage by using pr oper techniques to prevent h eat buildup duringwelding.Once the cabinets are installed, the best policy is to minimize modifications re quiring welding, particu larly n ear interna l cabinet doors. However, if welding isnecessary, it should be performed t o the s ame specifications, and the sam e techniquesshould be use d as those employed by the manufacturer in the original fabrication. Without this control, an inexperienced welder could warp a bulkhead o r window fram e byoverheating while trying to weld in a relative ly unimportant hos e clip or tool rack.

4


7/17

L E A K - C H E C K I N G A N D S T E R l L I Z A T I O N T E CH N IQ U ESThe method developed fo r leak-checking the SNAP line provided maximum leak-tightness with a minimum expenditure of ti me and effort . The sterilizatio n techniquesfinally perfected provided complete ster iliza tion with minimum degradation of equip

ment and few undesirable residues .The basic philosophy that guided the development of SNAP line leak-checkingtechniques was to avoid the indiscrim inate use of tr ac er ga ses containing halogen compounds. This effort was desirable for two reasons. First, the us e of halogens e arl y in the leak-check pro cess , when gr os s leakage is normally encountered, may saturatethe immediate area with halogens, which ra is e s the background of the leak detect ors,some times higher than the maximum acceptable leak rate (0.05 02; Freon/yr). Thissatu ratio n makes meaningful leak-checking with a halogen detector impossible, because,once an area is saturated, the effects persist for hours and, in some extreme cases,days. Another undesira ble effect, particu larly in a tightly sealed, multilaboratorybuilding with a carefu lly controlled environm ent (like portions of the LRL), is the distribution of halogens by the air-conditioning syste m to othe r ar ea s where halogen leak

checks may be in pro gre ss. The second reas on for avoiding halogens ear ly in the leakcheck is to prevent halogen satu raiio n of gaske ts. Once a gasket (e .g. , a window-framegasket) becomes satu rate d with halogens during a leak check, it is no longer possibleto tell whether o r not the leak has been eliminated. The ala rm will be trig gere d bymerely bringing the d etector clos e to the window. A satu rate d gasket may take days toclean up; yet only th re e to six attempts to leak-check can saturate it . For these reasons, the fi rs t step in leak-checking the SNAP l ine was to u se a pressure-decay test.This test is a simple, relatively fast one that can be repeated many times without causing saturatio n or othe r prob lems . The section of the piping or cabinet line under t es tis pressurize d by a small amount (4 inches water gage) of gaseous nitrogen. If thepre ssu re drops rapidly, gros s leakage is present, and an external bubble-type leakcheck can be used to locate the leak. Valve through-leakage cannot be detected withthi s method but can somet imes be isolated by opening and reseali ng the block valves,retorquing the block valves, or choosing another block valve in a slightly differentlocation. A slow decrease in pressure (1 to 2 inches water gage over the I-hour testperiod) indicates a minor leak that may not be detectab le with a bubble solution. In thiscase, a halogen leak test should be performed. The technique fo r using halogens(usually Freon-12) is simila r to the pressure-decay test. The section under test ispressurized to 2 inches wat er gage with gaseous nitrogen and then to 4 nches watergage with Freon . A halogen dete ctor gun is used to "sniff" joints and se al areas f o rleaks. The detector sensitivity is calibrated periodically with a standard leak. Leakareas a r e marked with str ip s of yellow tape for re pai r and retest .

In another leak-checking technique, helium is used as the t ra cer gas, and a mass spectrome ter tuned to the helium peak functions as the leak detector. This technique,which has been used in certain LRL cabinets with good re sul ts, has the advantage ofhigh sensitivity, plus rej ecti on of false signals fro m cleaning chemicals, curing adhesive, and so forth, which sometim es trigg er a halogen dete ctor . The vacuum leakdete ctor s normally used with helium req uir e only a n atmospheric probe to make themfunctional at 1 atmosphere.

5


8/17

The necessity that all cabinets and piping between inlet and exhaust biologicalfilters be leaktight cannot be overemphas ized, because only with a t ight syste m canbiological sterilization be per for med successfully using the SNAP-line-perfected techniques. Thes e techniques wer e developed over a 10-month period to meet th e requ irements assoc iated with back contamination. The procedure s finally developed andcertified for us e with lunar-contaminated syst ems required a ver y high degre e ofreliability; therefore, it was necessary to oversteri l ize the sys tem to ass ure a sufficient margin of safety. The steri lizin g agents tested during the developmental periodwe re formaldehyde gas gene rated by heating powdered parafo rmaldehyde, ethyleneoxide (ETO) gas diluted with Fr eon (12 percent E T 0 and 88 percent Freon), and liquid5 percen t sodium hypochlorite. The liquid sodium hypochlorite was used in piping thatcould not be made leaktight fo r gaseous steril izat ion. Various combinations of tem per at ur e and relat ive humidity wer e tes ted with the basi c goal of minimizing organ iccontamination and res idue introduced by the equipment-ster ilization pro ce ss . Thetechnique finally evolved fo r eff ective ste riliz ation with minimum contamination w a sas follows.

1. The relative humidity of the sys tem was r ais ed to approximately 50 percentby evaporating distilled water. The vapor was circula ted through the cabinets andpiping fo r 24 hours by a pumping system that interconnected all components of thesystem.2. A liquid mixture of 1 2 percent E T 0 and 88 percent Fre on was vaporized bypassage through stainless stee l coi ls in a 25" C wate r bath. Between the wate r tankand the system inlet, two glass ves sel s were installed to ser ve as combination sigh tglas ses and traps to prevent particulates or l iquid E T 0 fro m entering the system. Anin-line pressure gage installed between the vessels prevented pressure buildup in thesyst em. The pumping sys tem mentioned previously circulated the ETO- Freon mixtu rethrough the cabinets and piping. The cabinet interna l doors we re open during thisoperation.3. During introduction of the E T 0 and throughout the st eril izat ion period, therelative humidity was kept at approximately 50 percen t by evaporating additional dis

tilled water. Tempera ture w a s ambient and uncontrolled.4. The sterilization contact period w a s 24 hours af ter introducing the E T 0 andreaching the desi red r elative humidity.5. After the sterilizatio n period, the cabinets were flushed (one and a half gaschanges/cabinet/hr) with filte red gaseous nitrogen for 13 hours and exhausted into thecontaminated vent to the microbe inciner ator. This procedure prevented passage ofE T 0 into the room. The cabinet exhaust valves were then closed and the cabinetsvented to the room and fast-flushed (five gas changes/cabinet/hr) fo r 6 hours, com

pleting the steriliza tion proc ess . Spore st ri ps were introduced into the cabinet beforesterilizatio n and removed afterwa rds; upon removal, the str ip s were cultured andexamined to determine the effectiveness of the pr oce ss.

6


9/17

I N S T A L L A T I O N A N D O P E R A T I O N OF E N V l R O N ME N TA L M O N I T O R SOne of t he m ost significant modifications to the SNAP line aft er installa tion wasthe incorporation of an environmental monitoring syst em. The system w a s designed,fabrica ted, and installed to meet increasingly string ent environmental monitoring

require ments forwarded by the Lunar Sample Analysis Planning Team (LSAPT) afte rthe Apollo 12 mission. Fr om the standpoint of the technology involved, it was verymuch a state-of -the-art operation. Integrating the component pa rt s into the syst emwhile observing the res tric tion s of bacteriological contamination was especially challenging. Prelimi nary studies for future simi lar task s should include consideration and,if necess ary, design of an integrated environmental monitoring syst em. At this point,the ta sk can be accomplished efficiently and with a minimum of undes irable e ffe ct s.Later, the compromises required as a re su lt of insufficient cabinet penetr ations,installed piping, and so fort h make the task much mo re difficult.

The primary work cabinets on the SNAP line were equipped to monitor the moistur e and oxygen level s of the gaseous nitrogen inside the cabinets in pa rt s pe r million. The oxygen level of the inlet gaseous nitrogen could also be monitored. Adiagram of the moist ure and oxygen monitoring syst em is presented in figure 2 . A gas

2. C r o s s f i r s a m p l e va l ve a n d g a s - c h ro m a t o g r a p h c o n n e c t i o n .

Figure 2 . - The SNAP line oxygen-analyzer and moistu re-mon itor diag ram.7


10/17

chromatograph was used to monitor se ve ral of the tr ac e contaminants in the gaseousnitrogen at the inlet and exhaust; the chromatograph was operate d by Gas AnalysisLaboratory personnel.The mois ture level in the SNAP line was m eas ured using a commer cial monitorcomposed of a control and readout unit and seven remote sens ors. In operation, each

sensor acted as a capacitor in which ele ctri cal capacitance changed as a function of themoisture absorbed. An electro nic scanne r was fabricated in-house and installedbetween the s en so rs and the con trol and readout unit to allow automatic sequential scanning of t he outputs fr om all se nso rs . The scanner could be switched out of the circ uitfor manual selection and monitoring of the sen so rs. A dual-pen strip -ch ar t reco rd erwas installed to re co rd the output of t he cabinet sen so rs as meas ure d by the control andreadout unit. The par ticu lar monitor used in the SNAP line was chosen because thesensors were passive, easily installed or removed, and relative ly noncontaminating.The sensors, constructed of st ain les s steel and aluminum, had a sm all quantity of goldplating and epoxy.Any design incorporating easily removable sensors should also consider change-

out requirements. After cabinet cleaning and before sys tem st erilizatio n, the monitorsen so rs wer e installed in the cabinet ceiling with an O-ring and flange. Once installedand sterilized, the se ns or s could not be removed without requiri ng re ster iliz atio n of thecabinet line. (It w a s assumed, because all cabinets were interconnected and all exhaustlines were joined in a common manifold upstre am of the biological fil ter s, that anycomponent or syst em problem that could cause a los s of steri lity in one cabinet re quired complete system resterilization. ) This restric tion presented problems becauseof the vari able longevity of the se ns or s. Once installed, so me se ns or s might operat efor seve ral days and then become err at ic and fail, apparently because of the ir delicat econstruction. The majority, however, operated fo r months without problem s. Abetter design might be to install the sen sor s in a bypass loop in the cabinet-exhaustline. Should a sensor fail, the loop could be isolated and ster iliz ed; then, the sen so rcould be rep laced and the loop could be re ster iliz ed and returned to ser vice . In fact,a bypass loop was installed on cabinet 3 in the SNAP line where moistur e level wascrit ical ; but, because this sen so r never failed under mission conditions, the replacement feature was never used.

The amount of oxygen in the gaseous nit rogen w a s monitored by a commercialoxygen analyzer, which gave a di re ct readout in pa rt s per million of oxygen. A st ri p-cha rt rec orde r provided a permanent record of the ins trum ent readings. Again, bas icconsiderations in purchasing this in strumen t were the compatibility with cleaning, leak-checking, and steriliz ing agents, as well as the passive mode of sensing. The methodof sensing w a s unique, involving the permeatio n of the oxygen in the gaseous nitrogenthrough a diaphragm into a "fuel cell , " where the oxygen reacted t o generate an electr ic al signal. When expended (after sev er al weeks ), the cel l could be replaced like aflashlight battery. This approach w a s significantly different from those used in othertypes of available units.

During installation and leak-checking, it was discovered that the F reon leak checknormally performed on piping and cabinets was not sensitive enough for a unit capableof sensin g le ss than 10 ppm of oxygen. A second leak check wa s perf ormed using100 percen t bottled oxygen as the tr ac er gas and the oxygen analyzer as a leak detector.After the leaks detected with thi s test w ere rep aire d, the unit functioned normally.a


11/17

O P E R A T I O N A L O R G A N 1Z A T I O N A N D S A M P L E C ON TR O LSMission operational organization and sample controls f or the SNAP line weredeveloped during two simulations and ultimately provided tight control of samp le mate rial while remaining adaptable to new situations and req uirements .The initia l organization of the Op erations T eam is shown in figu re 3 . The Opera

tions T eam c onsisted of LRL (NASA and contra ctor ) and Planeta ry and Ea rth Sc iencesDivision personnel. Because the sample-proce ssing operation was the responsibilityof the LRL, the NASA LRL Sample Pro ces sin g Dir ect or (SPD) was placed in ove rallchar ge of the Operatio ns Team . All con trac tor personn el working in the cabinet line orwith assoc iate d equipment wer e under t he dir ecti on of a Te st Conductor (TC), who wasresponsib le to the SPD. All scientific personne l (curato r, LSAPT, and Lunar SamplePrel imin ary Examination Team (LSPET)) and thei r activ ities were directed by a Scientif ic Advi sor (SA), who, though shown in figu re 3 as directly responsible to the Processing Dir ect or, actually functioned in an independent and equal sta tus except duringemergency situations.

l i n e s of a u t h o r i t y_ - _ _ In t e r f a c e s

Tes t L I s a m p l e d e s c r i p t i o n t e a m sII S a m p l e P r o c e s s i n gLd v i s o r _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ C o n d u c t o rI I I

II[ C a b i n e t s 1. 2. a n d 3 - -~, I I C a b i r ! e t a I C a b l [ n . p l l C a b i L e t a

Figure 3 . - Original Operations Team organization, used in phase I simulation.The TC was responsib le fo r th e following specific duties.1. Assuring that pro cedures and instructions pertaining to the SNAP line werefollowed2. Assuring that sam ple numbers wer e obtained fo r all samples3 . Assuring that s ampl es we re handled properly to avoid damage or contamination

9


12/17

4. Recording tra ns fe rs of sam ple s from station to station within the cabinets andfro m the SNAP line cabinetry to other la borat ories5 . Assuring that all sampl es wer e stor ed safely within the cabinets and thatstorag e locations were recor ded at th e end of the workday6. Assuring that all sample numbering, tran sfe r, and histori cal information wasentered in the P relimin ary Analysis Computation Retrieval and Tr ansmis sion (PACRAT

computer systemThe SA was respo nsible fo r the following specific duties.1. Providing scientific personnel as requi red to support the LSPET with s ampledescription2. Providing scientific advice to the SPD on any ma tte rs requi ring deviation fro mplanned procedures3 . Providing scientific personnel as requir ed to furn ish sample-chippinginfor mationThe SPD was respo nsible fo r the following specific duties.1. Providing rea l-time direction to the TC for processing activities occurring inthe SNAP line2. Coordinating scientific r equ ire men ts with the SA3 . Maintaining the official sample identification and tran sf er re co rd log fo r the

SNAP line (log ent rie s to be obtained fro m data g athered by the TC)The organization shown in figure 3 did not function as well as desire d during thephase I simulation. The ov erall problem w as not re lat ed to the capabilities of theindividuals involved but t o the syst em within which they we re trying to work. As process ing op erations began, it quickly became evident that the TC was not able to monitorand super vise the routine processing operations, maintain the data-package fi les andsta tus logs, and at the sa me time manage the overall ope rations of the line. A s the TCbecame overloaded, he shifted much of his responsibility fo r routine processin g operations to the Sample Proce ssin g Advisor (SPA), who forme rly w as used in a strict lyadvisory capacity. This arr ang eme nt worked well and w a s use d until the completion ofthe simulation. Data-package review. and filing and the stat us log wer e s til l handledby the TC, although the need fo r change was a lso recognize d in this a re a.For the phase I1 simulation, the contra ctor portion of the Operations Team w a sreorg anize d (fig. 4). The m ost significant changes wer e made in the formation of afo rm al position fo r the SPA and in the addition of a n individual responsible f or documentation control. Although the rela tionsh ips between organizations defined fo r phase Isti ll applied fo r the second simulat ion, the duties of s om e of the principal team membe rs were slightly changed.

10


13/17

---------

Director----__ --___I JI

TestConductor_--- ---- - -- -. Advisor

I- _________ __ ._-____- -I

Sample Process IILines d authority Ad visor.__-_-_____- IInterfaces

Figure 4.- Revised Operations Tea m organization, used in phase I1 simulation.The duties of th e TC wer e re vise d as follows.1. Managing the ent ire con tract or effort on the SNAP line2. Scheduling inbound and outbound tr an sf er s f ro m the cabinet line with Health

and Safety Office personnel3. Assuring that the cabinets and all equipment wer e operating properly, that thenece ssary instrument readings and adjustments were made for optimum sys tem performance, and that discre pancies were noted by Quality Control personnel fo r late rresolutionThe d utie s of t he SPA we re as follows.1. Assuring that procedures and instructions relative to sample processing werefollowed2. Assuring that sam ple numbers we re obtained fo r all samples3. Assuring that samp les were handled properly to avoid damage orcontamination4. Assuring that all sample historical information was recorded on PACRAT andthe written log

11


14/17

5. Assuring sa fe stora ge of all sa mp le s within the cabinet s, and verifyingPACRAT location lis tings at t he end of the workdayIn addition to hi s previou s duties, the SA was al so to provide scientific pers onnelas requi red fo r sieving m ate ria l fro m the ALSRC and documented bags.The phase I1 organization (fig. 4) operated much bet ter than the phase I organization (fig. 3 ) . The workload was s pre ad m or e evenly among the people responsible f orthe various portions of the over all task, and the TC was finally able to obtain an overview of the en ti re opera tion instead of being engaged as a full-time recordkeeper. Thisorganization was a ble t o handle the Apollo 14 and 15 lunar -samp le p roc ess ing withoutdifficulty .Because of the la rg e number of luna r s am pl es the SNAP line wa s expected tohandle and the tight schedule imposed by time-critical experiments, the operationalconcept developed fo r the SNAP line was significantly different fr om that used p reviously in oth er areas of the LRL. In establishing the missi on organ ization and it s function, lunar-sample processi ng in the SNAP line w as handled as a manufacturing-typeoperation in which par ts (lunar samp les ) we re proce ssed through vari ous operationsaccompanied by a work or de r (data package) explaining the work to be perf ormed ateach work station. Operating personn el at each work sta tion wer e trained to performthe specific tasks for which that station was equipped. Thi s technique significantly

hastened the flow of sa mples through the cabinet line and provided a bette r quality product; that is , mo re written information on each sample detailing the process ing st ep sper for med and the data obtained. Thi s concept was quite different fr om the type ofsanlLJieproc ess ing previously per for med , in which a few highly skilled opera tors p erformed all the proc essin g operations with minimum documentation at one or two worksta tio ns and moved the nece ssa ry equipment into or out of the area to perform the task.

In acco rdanc e with this assemb ly-li ne concept of sampl e proces sing , a dat a package was generated to follow each sa mple through the proce ssing operations. Items ofdescr iptiv e information about each sam ple we re generated , collected, and identified asbelonging to that specific sample. A permanent samp le number wa s assigned to eachindividually identified sample as early as possible, and then all other information aboutthe sample was corre lated to this sample number. The collection point for the information generated during sam ple proce ssi ng was the data package. A data package containing the step-by-step procedure fo r proce ssing each sample, as well as spaces for theopera tors to write in significant information concerning the sample operations per formed, was begun on that sample as soon as it was individually identified. The dat apackages followed the s am pl es through each work station and we re tur ned o ver to th ecur ato r with the sa mpl es at the completion of p roces sing operations.This concept, routine in any manufacturing operation, enabled SNAP line personnel to handle rapidly l arge numbers of s am pl es with minimum confusion. It alsoallowed fo r a complete and rap id revi ew of the st atus of th e operation as necessary.Previ ous methods used were not neces saril y in e rr o r ; with fewer sa mpl es and a moreliberal schedule, an investigator could completely pr oc es s one sam ple at a time untilproce ssing of all sam ple s was completed. For this operation, however, it was moreefficient to handle the SNAP line as explained in this report.

12


15/17

C O N C L U S I O N SThe following conclusions wer e reac hed concerning the fabrication and operationof the st er il e nitrogen atmo sphere processing cabinet line for pro cessing lunar-samplematerial in the Lunar Receiving Laboratory.1. Relatively few compro mise s wer e re quir ed t o build the cabinet line in conformity with requirements for minimum organic contamination.2 . A mixture of powdered molybdenum disulfide, isopropy l alcohol, and distilled water w a s the standard lubricant developed for use in minimum organic-contamination environments. When sam ple s exposed to lubr ican ts are to undergoradio logical counting, counting of batches of molybdenum disulfide is also required.3 . The use of Lexan fo r cabinet windows was att empted because of the organicand radiological chara cteri stics ; however, the soft surfa ce, imperfections, lack oftransparency , and strong static-charge-collection tendencies rendered th is material

unsatisfactory.4 . Teflon diaphragms we re originally specified and installed in all valves in thecabinet line. Seve re through-leakage caused by the har dne ss and cold-flow chara cte ris ti cs of Teflon dictated repla cem ent of all valve diaphragms with Viton. These Vitondiaphragms have perfo rmed sati sfact orily through Apollo 14 and 1 5 mission preparations and operations.5. Cabinets to be use d in a minimum organ ic contamination environment shouldhave an American Standards Association number 4 satin finish or better on all internalsurfaces, as well as a l-inch minimum rad ius on al l co rn er s fo r eas e of cleaning.6. Cracks and crevices should be kept to a minimum.7. Welded seam s ar e pre fer red to gasketed seam s, for purposes of cleaningand sterilization. Cabinets should be welded into units consistent with transporta tionand installation requirem ents .8. A removable plate containing piping feedthroughs should be used in eachcabinet to simplify later modi fica tions of cabine t piping.9. Cabinet-fabrication quality is extremely cr itica l if the us e of chemical sealants is to be avoided. Two importan t areas demanding fabrication quality a r e (1)cutting and formin g window openings and (2 ) welding.

10. Welding operations on installed cabinets should be minimized. For thosemodifications requiri ng welding, manu factu rer's specification s and techniques shouldbe followed to minimize heat-induced warpage that may advers ely affect cabinet sealing.11- Leak-testin g should always begin with a pressure-decay test before a halogen o r helium leak check is made.

13


16/17

12. Halogen leak -testing should be perfo rmed sparingly to avoid satura tion ofthe work area o r gaskets around leaks with halogens.13. Helium can be used as a tr ac er gas for leak-checking if a helium leak detector with an atmospheric probe is available. The advantages of using helium a r e highsensitivity and rejection of fa lse sig nals fr om cleaning chemicals, adhesives, and s o

forth.14. An ethylene oxide gas -ster iliza tion technique was developed that completelysteri lized the cabinet line and all associated piping s yst ems with minimum posts terili

zation residue in the cabinets.15. The extent of environm ental monitoring should be determ ined in the designphase of a cabinet-line pr oject; the monitoring equipment should be integr ated into theline rath er than added afte r projec t completion.16. Changeout of environm ental s en so rs without shutdown or contamination of thecabinet line or contamination of operating per sonn el should be cons idered in the design

of monitoring equipment.17. Oxygen-analyze r sy st em s capable of detecting concent rations of oxygen le s sthat 100 pa rt s p er million should be final-leak-checked by using bottled oxygen as thetr ac er gas and the oxygen analyzer as the leak detector. A halogen tes t does not provide the necessary sensitivity.18. When numerous samp les ar e to be proc esse d through sev era l operations,it is best to design and man st ations in the cabinet line to perf orm the individual operations and then to pa ss samp les through the stat ions with documentation showing whichoperations ar e required. Each operator should document in writing the w o r k he perfo rm s, and the documentation should accompany the sa mple in all processing phases.

Manned Spa cecraft Cen terNational Aeronautics and Space AdministrationHouston, Texas, M arch 8, 1972076-00-00-00-72

14 NASA-L angley , 1972- 31 S-332


17/17

N A L A E R O NA U T I C S A N D S P A CE A D M I S T R A T I O NW A S H I N G T O N . D.C. 20546 PO ST AG E AND F EES PAID~. N A T I O N A L A E R O N A U TI C S A N DO F F I C I A L BUS1N E S S FIRST CLASS MAIL SPACE ADMINIST RAT IO N [SENAL T Y FOR P R I V A T E U S E 1300 USMAIL-

NASA 451

If Undeliverable (Section 1 5Postal Manua l) Do Not Retu

"T he aeronautical and space activit ies of th e U nit ed Stares shall beconducted so as to contr ibufe . . , . . t o the expansion of hun2an knowl-edge of phenomena iia the &?Uosphere and space. The Administrationshall.provide for the widest practicable and agpropriate disseminationof infoririation conce rning its act iviti es and the restilts thereof."-NATIONALAERONAUTICSN D SPACEACT O F 1958

NASA SCIENTIFIC AND TECHNICAL PUBLICATIONSTECH NICA L RE PORTS: Scientific andtechnical information considered important,complete, and a lasting contribution to existingknowledge.TECHNICAL NOTES: 1nformation.less broadin scope but nevertheless of impo rtance as acontribution to existing knowledge.TECHNICAL MEMORANDUMS :Information receiving limited distributionbecause of preliminary data, security classification, or other reasons.CON TRA CTO R REPORT S: Scientific andtechnical information generated under a NASAcontract or grant and considered an importantcontribution to existing knowledge.

TECHNICAL TRANSLATIONS: Informat ionpublished in a foreign language consideredto merit NASA distribution in English.SPECIAL PUBLICA TIONS: Informationderived from or of value to NA SA activities.Publications include conference prpceedings,monographs, data compilations, handbooks,sourcebooks, and special bibliograph ies.T E C H N O L O G Y U T I L IZ A T I O NPUBLICATIONS: Information on technologyused by NASA that may be of particularinterest in commercial and other non-aerospaceapplications. Publications include Tec h Briefs,Technology Utilization Reports andTechnology Surveys.

Details on the availability of these publications may be obtained from:SCIENTIFIC AND TECHNICAL INFORMATION OFFICE

NATIONAL AERONAUTICS AND SPACE ADMINISTRATIONWashington, D.C. PO546

apollo experience report processing of lunar samples in a sterile nitrogen atmosphere

Documents