ML19339A053

Informs That Design of RCS & Reactor Vessel Supports Reviewed Per 760607 Request.Rcs Designed & Constructed Per Rules of ANSI B31.1 W/Increased Exam Requirements

ML19339A053
Person / Time
Site:	Yankee Rowe
Issue date:	10/26/1976
From:	Johnson W YANKEE ATOMIC ELECTRIC CO.
To:	Office of Nuclear Reactor Regulation
References
WMY-76-109, NUDOCS 8010310684
Download: ML19339A053 (3)

Text

.

f N

f

-.\\

o Telip one 617 366-9011 I/ / 9A r \\

A..,.... n.

YANKEE ATOMIC ELECTRIC COMPANY

< Y.. ' ~ Na,6-109

Q

.as 4

c ss.

, Massachusetts 01581 20 Turnpike Road Westbo u

,Yauxes

~

October 26, 1976

• ~ -

i k, J '[u

9 United States Nuclear Regulatory Commission fif E" D Washington, D. C.

20555 L

Attention: Office of Nuclear Reactor Regulation Q

NOV 1197P 8;

Reference:

(a)

License No. DPR-3 (Docket No. 50-29) gf,.,r m t Q q

gyy ci (b) USNRC letter to YAEC dated 6/7/76 (c)

YAEC letter WYR 76-74 dated 6/8/76 (U

(d) MYAPCo letter MiY 76-110 dated 10/14/76 g

\\

(c) NUREG-0081 dated 6/1/76

Wd'

Dear Sir:

Yankee has reviewed the design of the reactor coolant system and reactor vessel supports for the Yankee Nuclear Power Station as a result of Reference (b).

As indicated in Reference (c), it is our position that the issue discussed in Reference (b) falls under the backfit criteria of 10CFR50.109, since the requested information exceeds that required by the design bases specified for the plant.

The reactor coolant system for the Yankee Nuclear Power Station was designed and constructed in accordance with the rules of ANSI B31.1, with greatly increased examination requirements. The examination requirements were-consistent with present practice.

The Yankee plant reactor coolant system was designed in accordance with adequately conservative codes and standards, whose allowable stress values were lower than present codes. The plant operating conditions are considerably below design conditions, thus reducing the actual stresses and further increasing the margin between operating stresses and allowable limits.

Reference (d) submitted. the results of a reactor coolant system failure probability study; the study showed that, assuming equivalent design parameters, an ANSI B31.1 designed piping system would require greater wall thickness than an ASME Section III designed system. The reason is that B31.1 allows the designer to not consider certain analyses by imposing lower allowable stresses to account for facters not considered.

This principle is discussed in Reference (e).

8010810[h twu

i

.c; J

United States Nuclear Regulatory Commission October 26, 1976 i

Attn Office of Nuclear Reactor Regulation Page Two 1

j Based on these factors Yankee considers the results of Reference (d) to be applicable to Yankee Nuclear Power Station. Thus, we feel the 1

j probability of the event discussed in Reference (b) to be sufficiently low to warrant its being considered not credible and thus not warranting further study.

Based on this information and the above mentioned backfit consideration, Yankee concludes that the concerns of Reference (b) have been adequately addressed, and no further action is necer.sary.

We trust you will find this information satisfactory; however, if you desire additional information, please feel free to contact us.

Very truly yours, YANKEE ATOMIC ELECTRIC COMPANY I

,f"')

i

~ A7/'dohnson- @$ 0}

W. P Vice President j

M /kg i

i 9

r I

I i

M w

v-9 u

7 y

w y

yy

, w c

--,--r7t ti-

NHC ronu 195 U.S. NUCLE AR REGULATOR f COHMlSSION DOCKET f auMEER

(.,.

50-29 2 7ci U ~ NfiC DISTRIB'JTiON FOR HART 50 DOCKET MATERI AL

• ^~

TO:

FROM:

DATE OF DOCUMENT Yankee Atomic Electric Company 10/26/76

. R. C.

Uestborough, Mass.

DATE RECEIVED W. P. Johnson 11/1/76 XtcTTER ONOTORIZED PROP INPUT FORM NUMDER OF COPtES RECEIVED jd:pRlGIN AL gUNC LASSIF IE o Thr2e signed OCO*v OESCRIPT ton E N CLOSU R E J

Ltr. re Our 6/7/76 ltr. & their 6/8/76 ltr.

& Ki/.FCo 10/14/76 ltr. & NUREG 6/1/76 ltr..

1 concernint; the Reactor Coolant System and Reactor Vessel Supports.

. J - n, (2-P)

A b --

~'

' - - ~

PIJ6MT NAME:

g

'lankee Rowe DISTRIBUTION FOR REACTOR VESSEL SUPPORT INFO FOR OPEPATING REACTORS PER MR. TRAMMELL 7-12-76 5AFEIY FOR ACTION /INFOR.'.1ATION 11/2/76 RJL

$1

_ ' ByJ,',icH cnTre Schwencer

. l I a c c Tr.' r n A n -

COller

_ _P.ROJ.ECT M'. NAGER:

Burr;er i __LIC, ASST:

Sheppard INTERNAL DISTRIBUTION h h G EII5 ]

l

'NP.C-P Y

^K;:ICliT i

2 3%TOCZY CliECK C. Tit'.M" ELL SilA0 i i M P. BAPANiJ!Si;Y i i P.

0.ilAN

_R, LOSNAK V. NOONAN

.9 l

FXTEHNAL distill!1UllON CONTilOL IJUMiti:H LPD3: Grccnfield, Mas 3.

t

,.uQ

/

l; y:

=-

1..,

.g C gg y

j ea aa

i

(:-

(.

Y:.2 9

3-July 22, 1977 1[ 2 Yankee Atomic Electric Company

=i=.

ccw/outenclosure(Contd)

@ 34 Public' Service Board if)

State of Vermont

g

)

120 State Street Montpelier, Vermont 05602 g..

E. W. Thurlow. President Y'5:/

Maine Yankee Atomic Power Company c

9 Green Street Augusta, Maine 04330 Mr. John M. R. Paterson 5

Assistant Attorney General State of Maine

n =

:_

Augusta, Maine 04330-

~=

Harold P. Green, Esquire

i?""'

Suite 1000

~".......?

The Watergate

~~i 600 New Hampshire Avenue, N. W.

Washington, D. C.

20037 Mr. Nicholas Barth-

~

Executive Director Sheepscot Valley ~ Conservation

. Association, Inc.

P. O. Box 125

.g Alna, Maine 04535

=.:

Mrs. Cali Holl'ander, President

==

SAFE POWER FOR MAINE Stockton Springs, Maine 04981 Mr. Robert R. Radcliffe Office of Energy Resources 55 Capitol Street Augusta, Maine 04330 "1 ^." ::

15P IIl 5;

. =

+

.;C7;; ;.-f C;'47.f;T h'.!'J:%!CC 1.COUC UCM UA ~~

U-'*'

I C..

4

+

y

.