ML20236T362

Forwards Draft of Questions Re Use of A-286 & Inconel X-750 Fastener Matls in Plant Helium Circulator Repair.Document Already Provided to Util

ML20236T362
Person / Time
Site:	Fort Saint Vrain
Issue date:	11/27/1987
From:	Heitner K NRC
To:	NRC
References
NUDOCS 8712010179
Download: ML20236T362 (2)

Text

- _ _ _ _ _ _ _ _ _ _ _ _ _ - _ _ _ _ _ _ _ - _ - _ _ _ - _ _ _ _ _ . ._ _ _ _ _ _ _ _ _ _ - _ _ _ - - - . - _ _ - - _ _ _ _ _ _ _ , - - _ _ - _ _ _ _ _ _ _ _

=e ,

h hochch No. so-u,7 g h t . ', . 15 'L'l b-Nde + o '. . Docket Faer 072 a.

ml y-N m ^, K. L, H e& ec F- tst . '

6% n am y ed '

P co Fo A s+, G ,m J

~ O L4 . d. C tG t' C4 O C LA. M -C v\

C. G R Cb @ / cr O C U. vt f bwr beem +o th Pa %)i % ~puJ,JeJ ra (n pun o+

Ccd oexd o , a a co-ci e n ce

.,% N R (t on ce L&-

O ,hb wt rt v\ t T \ Y4 O LA. O rc) vt bt C0f t f r ~

-)

\% L D Cm c O C c4. fh. $.

"K% . 9]A.  ;

871201o379 871127 9 .

p DR. ADOCK 05000267 '

eDe U-______________-._______ l

9 gpi

• t

. QUESTIONS RELATED TO THE USE'0F A k6 AND l y, , n l 4

4 j J.

INCONEL X-750 FASTENER MATERIALS IN

..F_0RT/ST. VRAIh! HELIUM CIRCULAT0_R REPAIR

1. l 5'I') []1(}3 "

[/,? 9 h

3

1. The preload' stress a i during assembly is an essential factor in 1 theavoidanceof1 tress' corr'bstoncracking(SCC);alsotheminimum l

preload. stress should exceed the value where fastener loosenino might' - 7m, l occur. What art the prtiAcad stressen that you intend to use on the A-286 "'I I and X-750 materials, compared to the specified yield and ultimate tensile  ;

strengths? hT g ,

9 A

2. The accuracy of preload stress depends on the tightening metMd chosen; turn of nut and mechanical torque wrench methods have low accuracies, 1 while the precision torque wrench and stretch measurements have http:er <l accuracies. What method will be 'uset' in the repair of C219'L helium circulator? y, j

. A xp k(,y ' j

3. What heat-treatmentsf are to be. specified for eact o/ @e fastener i I

materials; what is' thg specified hartfdQ4 after t r( heat-treatment? 9 d.f F y s .

w . . . . p d,

4. Manufacturincy, chemicals used for coolants during cutting opepted coc4 either initiate'or or if the. coolantscause do notSCC haveifcompositional there is no thermally limits onstable sul h r,frAibitor(h chlorine etc. Is this considered to be an issue in the manufuture of the - >

i .. fastener materials for the Fort St. Vrain circulator Yepair?-

C l.~

4 qi s 5. The Mo S or_ Molykqte is known as a detrimental. bolting ifNicant because it may 2decompose 1above 100*C and react.withyater (steam) to form hydrogen Mp

. sulfide corrodant~to cause SCC. What' expe a ental data are available to j indicate-that silicone-molykote (the lubricant specified for use in the Fort St. Vrain circulator repair) will be stable and compatible with the environment under circulator operation? "

J r , /

6. What quality assurance procedures will be used to inspect the fasteners during manufacture in order to ensure a high quality 1dstener and avoid 7 manufacturing defects? q qj A The A-236 bolts are projected to have a service life equivalent to the

< ' initially installed bolts, which failed by SCC after 60,000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br />

% circulator operation. In addition, these bolts are to be installed in fk captive location with respect to the rotating compopnts. Total bolt efeilure would/ result' only in loss of secondary intersppce pressurization.

Provide a description of the inservice.irppecQon/ p*/cgtam and/or procedures to be implemented to assure'contindmslbt;tgity '

of the fastener materials.

8. Describe the process that will be used during refurbishing the 7 circulators to clean the bolt holes in which the new fasteners will be i placed. '

/ g ,

4

9. The circulators may be driven by reheat steam, plant water, and/or fire water. Provide the specification that will be implemented for eadh of the drive materials. f. v p' <,