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Cover Sheet for a tianford Historical Document Released for Public Availability

Released 1994

Prepared for the US. Department of Energy under Contract DE-AC06-76Rt0 1830

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e

D O C U M E N T NO.

RGREA-607

S E R I E S A N D C O P Y NO.

DATE G E N E R A L E L E C T R I C

March 30, 1965 H A N F O R D A T O M I C P R O D U C T S O P E R A T I O N - R I C H L A N D , W A S H I N G T O N

T I T L E

O T H E R O F F I C I A L C L A S S l F I E D I N F O R M A T I O N

T H I S M A T E R I A L C O N T A I N S I N F O R M A T I O N A F F E C T I N G T H E N A T I O N A L D E F E N S E OF T H E U N I T E D STATES W I T H I N T H E M E A N I N G OF THE E S P I O N A G E LAWS, TITLE 18, u. s. c., SECS. 793 A N D 794, THE TRANS- M I S S I O N O R R E V E L A T I O N OF W H I C H I N A N Y M A N N E R TO A N U N A U T H O R I Z E D P E R S O N IS P R O H I B I T E D B Y LAW.

A U T H O R

W, F, Stevenson Quality Control Unit Fuels Engineering Production Fuels I r rad ia t ion Process- ing Department-GE

PROPOSAL FOR ELIMINATION OF 100 PERCENT INSPECTION FOR URANIUM GRAIN SIZE

A V E ACCESS

TO S I G N I N T H E SPACE P R O V I D E D BELOW. F I L E S R O U T E

R O U T E TO: P A Y R O L L NO. LOCAT I O N DATE S I G N A T U R E A N D DATE

I I I I I ~

I I I I I I I I I I

I I

,

f T h i s document c l a s s i f i ed by

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This document cons is t s

PROPOSAL FOR ELIMINATION OF 100 P~~CENT INSPECTION FOR URANIUM GRAIN SIZE

W o F, Stevenson Quality Control Unit

F’uels Engineering Subsection Production Fuels Section-IPD

March 30, 1965 To

UNCLASSIFIED

DISTRIBUTION LIST

RLREA-6 07

1, TW Ambrose 2, RE B a a r s 3. HE Berg 4 WA Blanton

6, CJ Denton 7, W J Ferguson 8, SM Graves 9, OH Greager 10, GL Hamnons 11, GB Hansen 12, RN Hettinger 130 KL Hladek 14, GA Huff 15. RD Jensen 16, WA Kline l T 6 RE Middaugh 18, HC Money 19, VH Nelson 20, EV Padgett 21. RW Reid 22, LH Rice 23. GM Schweikhardt 24. SJ Shipp 25. HG Spencer 26. WF Stevenson 2T0 J T Str inger 28, HF Tew 29. FL Van Wyck 30. EA Weakley 31. TH Whatley 32, 700 F i l e s 33, Record Center

5 . J A COW-

UNCLASSIFIED

A,

B.

C.

PROPOSAL FOR ELIMINATION OF 100 PERCENT INSPECTION FOR URANIUM _GRAIN SIZE

INTRODUCTION

Uranium cores have a grain s i z e specif icat ion of A8 t o MI s i z e i s denoted by a small "A" number and small grain by la rger "A" numbers. presumably has a high rupture potential . cause swelling, o r bumping, of the f u e l thus increasing t h e probabi l i ty of rupture f a i lu re ,

mge grain

Grain sizes smaller than A 9 denote an untransformed core which Grain s i zes la rger thaa A3

Presently, tests are made on a l l cores received t o determine compliance t o t h e above specifications. UT-2 Tester which gives t h e t e s t r e s u l t s i n voltage values. of the tester is done by adjusting t h e t e s t e r t o read out a voltage value which has been a r b i t r a r i l y specified fo r a ce r t a in known grain s i z e standard.

The tester used f o r t h i s purpose is t h e Calibration

Presently, t he vendor i s a l so t e s t i n g t h e outgoing product on a sampling basis

SUMMARY - As a r e s u l t of a recent study and analysis of a l l per t inent fac tors appli- cable t o t h i s s i tua t ion , it is concluded that 100% inspection of all l o t s received at HAPO fo r compliance t o grain s i ze specif icat ions i s nei ther warranted nor economically j u s t i f i a b l e , a system is proposed t o insure that screening is effected only when there i s an economic incentive,

Such a system requires thq t t he Feedsite (NLO) maintain i t s present process cont ro l sampling plan of 5 cores per ingot. t i o n at HAPO will be used t o detect major s h i f t s i n the qua l i ty of cores t o insure tha t screening i s used only when there i s an economic incentive. This sampling inspection, i n place of t h e present 100% screening, w i l l r e s u l t i n an estimated annual savings, t o IPD, of $52,500, based on the 0.0057% defective rate current ly observed i n t h e incoming material received a t HAPO.

In l i e u of t h e present screening,

A sampling receiving inspec-

DISCUSSION

T h i s study was conducted t o determine the most economic (to IPD) course of act ion f o r grain s i z e inspection, The a l te rna t ives are:

1, Continue 100% inspection of l o t s ; 2. Use l o t s "as is" with no inspection at a l l ; or 3. Use sampling plan on a l l l o t s t o determine whether screening is

necessary f o r any par t icu lar l o t .

R GREA-6 07

One hundred percent inspection f o r any charac te r i s t ic i s economically j u s t i f i a b l e only when t h e unit cost of inspection is less than t h e expected uni t f a i l u r e cost w i t h no insp c ion,

fa i lures , i n t h e absence of any inspection, is: t h robabi l i ty of rece ip t a t WPO of an aut-of-specification core ( 5 x 10- 6)f1q times t h e proba- b i l i t y of rupture of such core (1 x lom4)( times t h e cost of a reactor f a i l u r e ( a r b i t r a r i l y set at $20,000). expected un i t grain s i z e f a i l u r e cost t o IPD i f no grain s i ze t e s t i n g at a l l were done.

In t h e case here, t he uni t inspection cost has been set at $0,035 t 1 j , The expected un i t cost for

P This f igure, $0,000114 is the

The probabi l i ty of rupture set at 1 x Although t h i s may be, at best , a subjective estimate, it is concurred i n by responsible persons close t o the s i tua t ion and represents one of those instances where a management decision, with t h e accompanying r i sks , must be made on t h e basis of t h e best subjective estimates available, matter of reassurance, it should be noted that even though the above proba- b i l i t y of rupture were increased 100 times, the un i t f a i l u r e cost i s s t i l l 67% less than t h e uni t inspection cost.

above, may be debated,

As a

C o m p j . (Assume present observed defect ive r a t e of ,0057Z is constant fo r both s i tua t ions , )

1, Screenin<

2,500,000 @ $ 0,035 , $ 87,500*00

2, Use of Material "as is"

2,500,000 @ $ 0,00011~ $ 285#00

It is obvious t h a t , under t h e above conditions, #screening i s not economi- ca l ly j u s t i f i a b l e f o r IPD. It is of i n t e re s t t o note t h a t the probabili ty of failure (s ta ted above as 1 x loo4 , ieee, 1 out of 10,000) could be increased a hundredfold and "no screening'' would s t i l l be t h e more economic course of action, It can a l so be seen t h a t there some point at which screening is more economic, In the case here, t h a t point is an increase i n t h e defective r a t e of t h e incoming material t o >1,75% (providing that t h e probabi l i ty of rupture f o r a given defective element remains constant at 1 x 10-4),

Since it can be shown t h a t screening, t o be economically ju s t i f i ab le , i s contingent upon the qual i ty l e v e l of t h e incoming material, it follows that some sampling must be performed t o provide information regarding the qua l i ty l eve lo An e f f i c i en t sampling plan w i l l , with a high degree of assurance, indicate when t h e qua l i ty leve l of t h e incoming material is of a magnitude t h a t demands screening be effected t o achieve the most economic operat ion.

Consider t h e s i tua t ion where the defective r a t e fo r t he incoming material is 1,75%. A t t h i s l e v e l of qual i ty , and w i t h a rupture probabili ty of

I

1 x loo4, t h e cost t o IPD of using t h i s material "as is" (without screen- ing) would be, fo r 1,000,000 pieces:

1,000,000 (,0175) ( oOOOl) ($20,000) = $ 35,000.

If a l l t h i s material were screened, however, before using (assuming perfect screening) the IPD cost would be t h e same, i , e o ,

1,000,000 8 $ 0,035 = $ 35,0000

Therefore, 1,751 defective is t h e point a t which it does not matter (from an economic standpoint) whether t h e material i s screened before use or not. Our sampling,plan then, should have a ,5 probabi l i ty of detect ing l o t s of material t h a t a r e of t h i s percent defective, our sampling plan t o be su f f i c i en t ly e f f i c i e n t t o detect l o t s having a greater percent defective so t h a t such l o t s may be screened and t o pass l o t s which are less than 1,758 defective,

A t t h e same time we des i r e

From Quality Control Manual #3, Quali ty Policy and Procedures fo r F'rocured Materials, w e see t h a t for an average l o t s i z e of 4000, and Inspection Level 11, a sample s ize of n = 200 i s specified, The operating character- i s t i c curve for t h i s sampling plan has, fo r a specified AQL of 065, i ts 0 5 probabi l i ty of acceptance near t h e 1075% defective point (see Figure 1) , Thus, of the various sampling plans contained i n M i l Std 105D (Standard Plans for Attr ibutes Inspection) the sampling plan with an AQL = 665 i s most appropriate for use hereo Note, f o r example t h a t use of t h i s plan w i l l insure, with 13% r i s k , t h a t l o t s ranging i n s i ze from 3200 t o 10,000 and having 1% defective w i l l be used "as is", On t h e other hand, s i m i l a r s i z e l o t s which a re 3% defective &ve an 85% chance of being screened,

To minimize the amount of sampling inspection involved, an a t t r i b u t e s multiple sampling plan ( see Quality Control Manual #3) w i l l be used, I n i t i a l l y , normal inspection and Xnspection Level I1 w i l l be usedo Receiv- ing Inspection shall be responsible for operation of t he sampling plan i n accordance with t h e pol ic ies and procedures as specified i n Quality Control Manual #3 and as directed by Quality Control, As s ta ted above, an AQL of *65 will apply. material , received from the vendor, and on a l l "K" l o t s t h a t a r e re jected by t h e sampling plan, require any changes i n t h e present procedures used at NLO, t h i s degree of inspection at HAPO two t e s t r

Sampling inspection s h a l l be performed on a l l l o t s of "K" Screening s h a l l be performed on a l l other l o t s , which are

The implementation of t he proposed system at HAPO will not To accomplish

one operator, and three- quarters maintenance man w i l l be requiredo 717'

The Spec ia l i s t , Nondestructive Testing, shall be responsible for assuring t h e legitimacy of the material accepted and rejected by t h e l i n e t e s t e r s used, Coordination must be effected between Receiving Inspection and the Special is t p r ior t o t h e re jec t ion of any inspection l o t r

The Special is t , Nondestructive Testing, s h a l l be responsible fo r t h e imple- mentation of a system t o insure continued agreement between t h e t e s t e r s

I

RL-REA-607

used a t the vendor's s i t e and the testers used at W O O s h a l l a l so insure agreement between t e s t e r s within each t e s t i n g s i t e and within each t e s t e r over time, Such system shall be documented, approved by Quality Control, and issued i n suf f ic ien t quantity t o a l l te'ster operating personnel, Vendor Liaison personnel shall be responsible for assuring compliance, by vendor personnel, t o such d i rec t ives and instruc- t i o n s

Th i s system

Vendor Liaison shall be responsible for effecting, and designating t o Receiving Inspection, inspection l o t s of such nature as t o insure the maximum, p rac t i ca l homogeneity as concerns the grain s i z e charac te r i s t ic , Vendor Liaison shall a lso, t o t h e extent practicable, c r i t i que t h e vendor's plan for control of the heat treatment operation, observe compli- ance t o such plan, and c a l l t o t he vendor's a t ten t ion any discrepancies or violat ions observed,

Receiving Inspection s h a l l be responsible for ear ly not i f ica t ion t o Vendor Liaison and Qual i ty Control of any detrimental trending of grain s i ze qua l i ty

Implementation of t h i s system can be effected immediately upon approval,

W, F, Stevenson, Senior Engineer Quality Control

WFS/eb Attachments: 5

REFERENCES :

(1) See Attachment #3 (2) See Attachment #4

U RGREA-607 FIGURE I

1600

6 90

.80

e 3 0

r20

.10

0

I ! , : : : ! ! ! ! , ! ! a $ . ? , ! ! ! , : : ! ! ' ! ! ! I . . ! 1 ' ! : , . , ! I . ! . ,

0 1 2 3 4 5 6 7 PERCENT D E F E C T I V E OF INCOMING MATERIAL

-7-

-8-

C . Tclstcs o p e r ~ t i ~ n cs outl ined in lTLQ Sa? 15-C-2.01. A revision of tnis SOP shoald be r;vailaSle soon.

-9-

R I C H L A N D , W A S H I N G T O N

if3

'7 R . .. L-REA-607

1GG.rJO $ 0 . 081 d

. -.

February 9 , 1965

1.:. F. Stevenson, Engineer Qcal i ty Control Unit ,"Usls Engineering Operation .

UT-2 SAi4PLING

5 e probabi l i ty o f - f a i l u r e of a transformed core with out- f- s2ecif iczt ion grain s i ze may be es t ina ted as l/104. zk 3 e s t an educated guess, as we have no data t o base the e s t i c z t e on.

This i s

The probabili ty of producing an out-of-specificztion core at - : ~ 9 riay be arrived at by adding the percent UT-2 r e j e c t s z;t ;:LO a d &PO. The UT-2 r e j ec t r z t e at BLO f o r the period A p i l through Septen'aer 1964 w a s 0.27 percent.

..--

Vendor Lizison

cc: VV Padgett LA3 Fi l e

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