ML20024G405
| ML20024G405 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 10/14/1975 |
| From: | Mayer L NORTHERN STATES POWER CO. |
| To: | Ziemann D Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 9102120387 | |
| Download: ML20024G405 (3) | |
Text
l p.
O 4
/
NOS
\\
w n
NORTHERN STATES POWER C0MPANY t ' k /p M I N N E A P O L.[St MIN N E GOTA 95401 b{.
$% f A
?
~
u s
Octdbei14l.1975 y y rp oggp
'g q
,o
-.13m ' -
00, 171975*
s 00 Tit 1975
- h 6J A
3 fe c.
~?
Mr,,DM.$Z' 'emann, Chie f i
Q s.t. 6*C T'"
~
.g BDivisioniof' Reactor Licensin $ QQ
%g f.'Opdat1 4 Reactors Branch #
l se to V,
- S,15. Nuclear. Regulatory Commi U
N a
'Washingto6'DC 20555 c)
N
,p -
Dear Mr.. Ziemann:
I MONTICELLO NUCLEAR GENERATING PLANT Eruidoi Docket No. 50-263 License No. DPR-22 Response to September 24, 1975 Letter on CRD Collet Housing Cracking This letter is written in response to your September 24, 1975 letter and proposed technical specification changes concerning cracks observed in control rod drive collet houshgs at plants similar in design to Monticello.
We have reviewed the proposed changes and the safety evaluation to determin, the effect the changes will have on plant safety and operation. While we do not object to issuance of the interim technical specification based upon the cracked collet housing exper-ience, we ask for consideration of the following comments prior to its issuance.
We current technical specifications allow operation to continue with up to six inoperable control rods if the shutdown margin can be maintahed.
The li2ait of six i
was established on the basis of it being indicative of some unidentified generic problem. While collet housing crar'.ing has not caused an inoperable control rod to date, it falls in the category of a potentially generic cause of inoperability.
The NRC safety evaluation does not identify a specific basis for the requirement to shut down on seeing the symptoms of one cracked collet housing, nor does it specifically identify differences in this potentially generic problem in support of the reduction in number of inoperable rods.
l The proposed changes will increase the likelihood of plant unavilability through forced shutdowns.
Such shutdowns may be the result of collet housing cracking or some unrelated problem that cannot be distinguished from housing cracking and for which shutdown is unwarranted. We believe that the potential loss of avail-(
ability can be minimized greatly without compromising safety by allowing operation l
to continue until multiple control rod drives show the symptoms of complete circum-ferential cracking of the collet housing.
We would also like to suggest two clarifying changes to the proposed technical spe-cifications.
The second sentence of proposed specification 4.3. A.2 (page 76) refers to " control. rod drive mechanism damage." This phrase should be restricted in scope 9102120387 751014 12071 PDR ADOCK 05000263 P
PDR 1
(
NOR ERN CTATED POWER CO ANY
(
Mr. ' D.' L. Ziemann 2
October 14, 1975 by the words "a failed collet housing." The last sentence of the proposed bases for 3.3A and 4.3. A (page 83) refers to a " severed rod."
This term should be changed to read " severed collet housing."
g I'
Yours very truly,
-^
p,'
iLs; Oic Mayer, E j
Hanager. Nuclear Support Services LOM/MHV/ deb cc:
J. G. Keppler G. Charnoif MPCA Attn:
J. W. Ferman 1
s
'l i.
- I
(
w
- r NRC DigRIBUTION FOR PART 50 DOCKET g2TERIAL
'i
- i
~
(TEMPORARY FORM)
CONTROL NO:12071
~
FILE:
s
'l FROM.:forthern States Power Co, DATE OF DOC DATE REC'D LTR TWX RPT OTHER E
"bs h 10-14-75 10-17-75 XXX o
n.
ORIG CC OTHER SENT WRC PDR XXX T O; g* ^'.9 ;-l[. 7 pg 7jefjtnn1 Signed 39 SENT LOCAL PDR CLASSc,UNCLASS..
PHOPINFO INPUT NO CYS REC'D DOCKET NO:
E4[ EN$k 40 50-263 DESCHlPlih:"
ENCLOSURES:
Letter ter our' letter on 9-24-75.....
Letter and proposed Tech. Spec Change concerr ing CRC Collect Housing Cracking, and correct
"~
ion to page 83 to read.......
(40 Copies Enclosure Received) 4 i
~ PLANT NAME: Monticello FOR ACTION /lNFORMATION SAB 10-20-75 SCHWENCER (L) fZlEMANN (L)
REGAN (E)
BUTdR (L) f W/ Qpies W/Acopies W/4 Copies W/ Copies CLARK (L).
STOL Z (L)
DICKEF. (E)
LEAR (L) i W/ Copies W/ Copies W/ Copies W/ Copies ACKNOWLEDGED PARR (L)
VASSALLO (L)
KNIGHTON (E)
SPIES l
W/ Copies W/ Copies W/ Copies W/ Copies Tm MrYD bTT. A 7b4 KNIEL (L)-
PURPLE (t )
YOUNGBLOOD (E)
Lpg uV D v1 U
W/ Copies W/ Copies WJ Copies W/ Gopies INTERNAL DISTRIBUTION hR EG FI LD.
TECH REVIEW DENTON LIC ASST A/T IND.
'j.
-- MTlO PO R
~SCHRCEDER GRIMES
/R. DIGGS (L)
BRAITMAN
,/OGC, ROOM P 506A MACCARY GAMMILL.
H. GEARIN (L)
SALTZMAN fGOSSICK/ STAFF KNIGHT KASTNER E. GOULBOURNE (L)
MELTZ CASE PAWLICKl BALLARD P. KREUTZER (E)
'LANS GIAMBUSSO SHAO SPANG LE R J. LEE (L)
BOYD STELLO fJ. RU.THBROOK(L)
MCDONALD MOOttE (8 )
HOUSTON E NVI RO.
S. REED (E)
DEYCUNG (L)
NOVAK MULLER M. SERs/ ICE (L)
DUBE (Ltr)
SKOVHOLT (L)
ROSS DICKER-S. SHEPPARD (L)
E. COUPE GOLLER (L) (Ltr)
IPPOLITO KNIGHTON M. SLATER (E)
PETERSON-P. COLLINS TEDESCO YOUNGBLOOD H. SMITH (L)
HARTFIELD (2) i DENiSE J. COLLINS REGAN S. TEETS (L)
KLECKER
_ REG OPR LAINAS PROJECT l.DR G. WILLI AM3 (E)
EISENHUT p
./ FILE & REGION (2)
BENAROYA A1M V. WILSON (L)
WI GINTON
'l.
MIPC VOLLMER HA R LESS R, INGRAM (L)
M-I M. DUNCAN (E)
EXTERNAL DISTRIBUTION
/ - LOCAL PDR_M_irgawolis, Minn.
1 l
8
/1 - Tic (ABERNATHY) (1)(2)(10) - NATIONAL L A P7 1 - PDR SAN /LA/NY
/ - NSIC (BUCHANAN) 1 - W. PENNING!Oiv, Rm E 201 GT 1 - BROOKHAVEN NAT LAB 1
1 - ASLB 1 - CONSULTANTS 1 - G. ULRIKSON ORNL 3
1 - Newton Anderson NEWMARK/BLUME/AGBABI AN
,M-- ACDS XXXKIMKXX/SENT to L.e,. R. Diggs-gl
/] YY l
}t
..