ML19220C441
| ML19220C441 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 01/15/1969 |
| From: | Racquel Powell US ATOMIC ENERGY COMMISSION (AEC) |
| To: | Boyd R US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| NUDOCS 7905010575 | |
| Download: ML19220C441 (5) | |
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,1 ATOMIC ENERGY COYMISSION
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W January 1;.
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?,czer S. 3cyd, Assis tant Director ':r Reartr r -Pro j ects, O R'.
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s t 3ackground In the Oyster Creek Unit No. 2 A=endment No.
, Jersey Central Pcwer and Light Ccepany (JC?SL) has proposed to change the centrol red drive =echanisa frem the rack-and-pinion type drive to the roller-nu: type drive sechanism. The rack-and-pinion drive mechanist. has been approved for previously-reviewed 35W plants. A 7ersion of the roller-nut type drive mechanism has been incorocrated into the Westinghouse designed nuclear systen for the Ginna plant to position the partial length control reds. Although we do not knew che exact reason for the design change, it is our understanding f rom dis:us-siens with the applicant that part of the reason concerns the high pressure seal in the rack-and-pinion drive that coul result in a saintenance problem.
Cemearison of Design Criteria A preliminary review, including a ec=parison of the 35W design criteric for the rack-and-pinion drive sechanis: and the roller-nut drive mech-anis indica:e the design criteria for each type drive mechanism are the sa=e except for the folicwing differences.
1.
Rod Dri7e Soeed a.
Rack-and-pinica 25 in/ min i 10".
b.
Roli.tr-nut 30 in/ min
,10'.
2.
Centrol
.d Assembiv Insertien a.
Rack-and-pinion:
Inser icn shall have priority ever withdrawal, and the drive will be capable cf over-cesing a stuck-red condition ecuivalent to a 400-15.
weight.
b.
Rciler-nut: The above criterion has been leieted.
Discussicn with 3&W indicates the roller-nu: drive wi' be capat'.e of applying a 400-15. insertion force, but it will not be automatic as was the case for the rack-and-pinion drive design.
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s 1. a 700501oS7S'
s Roger S. Scyd 3.
Control Red Assembiv Positioning a.
Rack-and-pinion (no reported cri:urion) 5.
Ro ller-nu: drives will be capeble of red inser:icn and withdrawal in the core for reactor centrol.
In additien, the rechanis: will provida inserti:n (30 in/=in) of control rod assemblies for energency conditions.
4 Grouc Withdrawal The roller-nut centrol red drive system design allows only rwo cut of three regulating control red assembly graues to be withdrawn at any time, whereas the rack-and-pinion design allows two of f cur regulating centrol rod assembly groups to be withdravn at any time.
This change frc two cut of four to evo cut of three results frc the use of eight control rod drive assemblies to position partial length rods. Utilization of par: length reds reduces the total number of regulating control rod assembly groucs frc four groups to three groups.
The diff erence in the control rod drive speed does not affe-t safety aspects of the plant since 35W has provided analyses of the red withdrawal accidents as a function of the reactivity rate.
Based upon these analytical results, the increase of the red drive speed frc 25 inches per minute to 30 inches per minute will still meet the design limits (1) that reactor thermal power is less than 1117.
rated pcwer or (2) the reactor ccolant systen pressure will be less than 2515 psia.
Discussions with 35W indicate the capability to drive a stuck rod down with a 400-1b. force applies to the roller-nu: drive as well as to the rack-and-pinica type drive.
The autenatic run-in f eature of the rack-and-pinion drive follcwing a scra: is not possible with the roller-nu drive since disengagement of the roller-nut for the scra trip is accceplished by deenergicing the drive noter.
The rack-and-pinicn drive is the only drive used in previously-approved
?WR plants which has the aute=atic drive-down capability for stuck rods. Ecwever, the new design allows for drive-in by oper2:or actica if necessary.
A third design basis for the roller-nut drive is tha: the drive be capable of rapid insertion (i.e., scra: 3r drive-dowr by operator actien) of the control rod asse=blies for energency conditions.
OO 74.
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Roger S. 3c d f Manufacturing At the present time B&W has indicated that it will probably be manu-facturing and asse bling portions of the reller-nu: drives with sete of the drive components being supplied by Royal Industries of Santa Ana, California. Royal Industries ranufacturers the roller-nut drives for the Navy nuclear systems at the present time.
3&W indica:ed the first set of drives might be ranufactured by Royal Industries and may be used in the Three-Mile Island nuclear steam systen. Specifica-tions and the quality assurance and quality control programs f ar fabrication, assembly and testing of the roller-nur drives will be the responsibility of 36W.
Discussicas with B&W indicate the drawings and specifications will be similar to the drawings and specifications presently used by Royal Industries.
Babcock & Wilecx has ccupleted an R&D program for the roller-nut drive 2echanism and intends to report the results in first quarter of 1969.
This R&D program included a full scale prototype of the roller-nu drive and control rod asse bly.
The following areas were investigated to demonstrate the perfor:ance of the roller-nut drive mechanism:
- operational and life cesting of roller-nut drive under reactor operating conditiens of temperature, pressure, flow, and water chemistry
- measure =ent of trip time with raxitum isalignment
- caterial cc patability and wear characteristics in reac:cr enviren=ent
- life test drive f or equivalen: 20-year usage.
?csition Indication The roller-nut drive rechanism uses two types of devices for indicating the control rod position. Absolute rod positica indication is provided by =agnetically operated reed switches and a relative position indica-tion is provided by a small pulse stepping =ctor coupled to a potenticceter.
The absolute posi:icn indication will have a positica accuracy of - 2.1%
which corresponds to j-2.9 inches based on a total stroke of 139 inches, while the relative posi:icn indica icn will have an accuracy of ;- l.-';
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or ' 2.4 inches. The reed switches will also be used to indicate full-ir and full-cut limits. The position accuracy of the rack-and-pinion drive mechanis: is j-1. 71 o r ; 2. 4 inches based on :he 139-inch s:rcke.
Cc=carisen of Drive Mechanisms The folicving table provides a comparisen of the drive mechanises presently pronosed by the diff erent ?WR nuclear stea suppliers.
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4:ofII'Al l:3 ):4 (!!' CllAl:AC1 ER 1 S l'IC:i 0F l'tJR CONTI:oI. Illt i VE lil-'S I GilS fLilwock & WIleox Westinghonso Combustion 1:ne,ineer i no f
'l i;
R ick-h-l'in ion
!!o l le r-fin t Minnetic Jack Roller-Nut Rack & Pinion flaguet Ic. lack Typ" o
tio. of im i ves/ r.. ic t or 6n 69 52 3
4 'i 65 No. of 1:otts/tir ive 16 16 20 20 1 (Cinriform) 5 or 10 Con t i o l Roil l'o i son An In Cil Ag In Cil Ag I n Cil An fit Cil ll C Il C 4
4 Total Roil Worth ( A k) 10%
10%
7%
9%
9%
Strole I.eng t li; in.
139 139 144 144 112 137 Dr iv e S p ecti ; in/ min 25 30 45 15 46 23 Typo Sc ram Gravity &
Gravity Gravity 11 o Scram Gravlty &
Gravity Auto Drive-(Pa r t i a l Auto Drive-Down lei. ' h ro(Is)
Doun Position I ntlicat ion Goar pot &
flagne t i c Differential Differential Gear-pot &
lj l r rerential linluc t ance Reet! Swit elies Transformer Transformer
!!a e,n e t i c Transformer Co11 tiotor-pot Reeri Sw I t clies Trip Time l.4 sec. for 1.4 sec. for 2.0 sec. full 2.5 nee. 90%
/_2 nee.
2/3 insertion 2/3 insertion insertion insertion d
I' '
Design pressure; psig 2500 2500 2485 2485 2500 2500
{$
Design pressure,. *F 650 650 650 650 650 650 1 '
CO R&l) Program Yes Yes 11 o Yes Yes Yes Approveil f or CP Yes (all ll&W)
. tio Yes Yes (all Yes Yes (Pla l n e Wes t I nglious e (Pa l i sailes )
Yankoe)
Reactors)
No. of parttal l eng t li ro<l (I r lven 8
8 Ilone 8
4 lies i g ne r H&W ll&W West.
West.
Cemh. Engr.
Comb. Engr.
FI innl ac t u re r ll&W ll&W anil West.
West.
Comb. P.n g r.
Cc.in. En o, r.
Royal I ncl.
o
Roger S. Soyd Failure Analvsis Babccck 5 Wilecx has indicated that 1: will review the rack-and-pinico crive f ailure analysis presented in the Three-Mile Island PSAR Supplement No. 1 cuestions 4.6 and 0.8.
It will submit a similar analysis for the roller-nut drive in Anend=en: No. 6 for the Oyster Creek Unit No. 2 PSAR Seismic Design The roller-nut drive mechanism will have a support structure a: the top of the drives pressure housing to provide lateral support. A missile protection shield will be provided around the centrcl rod drive mechanis: to provide =issile protection to the contain=ent liner and the drives. 3&W indicates that the seismic design analysis of the rack-and-pinion drive =echanisms presented in the Oconee ?SAR Supple =en:
No. 4 re=ains applicable.
It does not intend to repeat the analysis for the roller-nut drive asse bly since the toller-rut drive assemblies are structurally =cre stable, due to the lower center of mass and decreased bedding =ctents, than the rack-and-pinion drive asse:blies.
Su==arv This preli=inary evaluation of the control rod drive roller-nut :ech-anism was primarily a cc=parison of the design criteria used by the designer with regard to adequacy to ensure a safe and reliable ccatrol red drive rechanism. The design, operating principle, and materials used in the roller-nut d:ive mechcnism appear to have been ecnfirmed by development testing as well as operational service.
We will centinue our review of all the foregoing satters; however, on the basis of our prelisinary review, we believe :ha: the roller-nut drive =echanism say be censidered as an acceptable centrol rod drive
=echanism and plant to continue our review on this basis.
Cc==ents by RT wou'd be appreciated on any of the feregoing.
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Ray =ond R. Powell Divisica cf Reactor Licensing cc:
?. A. Merris F. Schroecer S. Levine R. DeYoung 3 ranch Chiefs, DRL
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