ML20024G760

Application for Amend to License DPR-22,revising Tech Spec Table 3.7.1

ML20024G760
Person / Time
Site:	Monticello
Issue date:	07/10/1973
From:	Larkin W NORTHERN STATES POWER CO.
To:
Shared Package
ML20024G759	List: ML20024G758 ML20024G760 ML20024G762
References
NUDOCS 9104290336
Download: ML20024G760 (5)

Text

,

N 5- F UNITED STATES ATGIIC ENERGY CGMISSIcu Jgfp g._ p, c,n:n;c, y vsL$w qqap. ,

NORTIIERN STATES POWER COMPANY {.ylpi * ?W' Monticello Nuclear Generating Plant 4QQ NDd

-9.

-o a,ur 63 ?p y, n h,,*ah [Y  %&v l REQUEST FOR AUT110RIZATION OF 4 5-A Cl%NGE IN TECl!NICAL SPECIFICATIONS .fNE W.

OF APPENDIX A ,.gf G

-W

,?

1. • ~+-

L 10 PROVISIONAL OPEl% TING LICENSE NO. DPR-22 -

M*Ee7U"L ifl 619

.y b comissrogsi miirnan -

g gassuway ,,

(Chango Request Dated July 10, 1973) g,4 " ,

sectme p

g ,

Northern States Power Company, a Mint ta corporation, reqYe'iiids""';

authorization for changes to the Technical Specifications as shown on the attachments labeled Exhibit A and F.xhibit B. Exhibit A describes the proposed changes along with reasons for change. Exhibit B is"a copy of the Technical Specifications revised to incorporate the pro- '^ * * .

posed changes,

~ ~y ,

This request contains no restricted or other defense in'fobaation. "

liORTilERN STATES POWER CGIPANY yy sp,;'7

,V/ ,C G ~.$Inhv fl.

Wade Larkin Group Vice President - Power Supply b,

On this 4[ dayof,bn// , 1973, before me a notary public in and for said County, personally appeared Wade Larkin, Group Vice President - Power Supply, and'being first duly sworn acknowledged that he is authori::cd to execute this document in behalf of Northern States Power Company, that he knows the contents thereof and that to the best of his knowledge, information and belief, the statements made in ,1t are true and that it is not interposed for delay.

)

/ /)

M 6hh

' John J4mith Notarp Public, llennepin County, Minnesota JOHN J. SMITH Notary Pubhc. Hennepin County, Minnesete My Commission lapires March 3.1976 9104290336 730710 5465 PDR ADOCK 05000263 P PDR

EX1tIBIT A nh

, c;.g w i h1 wn.m:

MONTICELLO NUCLEAR GENERATING PIANT' '[# .w.g/'P l DOCKET No. 50-263 y g,g;g

$x% c , .a.w gp CHANGE REQUEST DATED JULY 10, 1973 4(*y g %g . "

l PROPOSED APPENDIX A 0F CHANGES PROVISIONAL TO TECHNICAL OPERATING ~ * *SPECIFICATIONS " ' *i LICENSE NO. DPR-2. e @ jf4 & ,

% W:tMME

,8 -

(,,- y PROPOSED CHANGE onSp[^/

..s m r on page 153, delate from Tabic 3.7.1, " Primary Containmen Isolation,"

the entry " Suppression Chamber Vacuum Relief From Reactor Building" under the colu=n " Valve Identification" along with associated" entries in the table.

REASON FOR CHJWGE The original entry of these valves into Table 3.7.1 was not int'en'ded and as included constitutes an error. Although the torus to secondary contain-ment vacuum breakers are designed to function as isolation valves, they are not included in any of the isolation logic schemes and are, thus, not part of isolation group 2, as noted in Table 3.7.1. The normally closed valves are operated only by a hand switch or a vacuum switch.

PROPOSED CHANGE On page 147, replace " Limiting Conditions for Operation" and " Surveillance Requirements," 3.7. A.4 and 4. 7. A.4, respectively, with the following:

" Limiting Conditiono for operation 3.7.A.4 Drywell-Pressure Suppression Chember Vacuum Breakers >

a. When primary containment is required, all drywell-suppression chamber vacuum breakers shall be operable and positioned in the closed position as indicated by the position indication system, except during testing and except as specified in 3.7.A 4.b and c, below.

b. Any drywell-suppression chamber vacuum breaker may be nonfully closed as indicated by the position indication system provided that drywell to suppression chamber differential pressure decay does not exceed that shown on Figure 3.7.1.

P

, , 7., r

> +

EX1tIBIT A $ J I iM i

' . g .

r

.%$ ]

.s p v-

c. Up to two dryvell-suppression chamber vacuum breaker k erable provided that: (1) the vacuum breaker is de '~ gr fully closed as indicated by the position indicati ~~~

drywell to suppression chamber differential pressurai .A not exceed that shown on Figure 3.7.1 or (2) the"^ " ptl-is secured in the closed position."

" Surveillance Requirements

'ilth hf g , ,,

s a &N4 n.A 4.7.A.4 Drywell-Pressure Suppression Chamber Vacuum Bra 4rs W wtnen yp

a. Operability and full closure of the drywell-suppression"$ 'd

e  !

vacuumbreakersshallbeverifiedbyperformanceofthe*follairidjtu (1) Monthly each operable drywell-suppression chambN cu breaker shall be exercised through an opening-closing cyclen

-% ggggsa, ,

(2) Onceeachoperatingcycle,drywelltosuppressionchac.bar."[

1eakage shall be demonstrated to be less than that equiva!

lent to a one-inch diameter orifice and each vacuum breaker "

• shall be visually inspected.

e w w. Q t3 s

b. When the position of any drywell-suppression chamber vacuuin'broskar valve is indicated to be not fully closed at a time when such . closure is required, the drywell to suppression chamber differentiallressure decay shall be demonstrated to be less than that shown on rigure 3.7.1 immediately and following any evidence of subsequent operation of the inoperabic valve unti1 the inoperable valve is restored to a normal condition." *'

• 3.7.A Bases ,

. .s n On page 158, add the following between the exist.ing third and fourth para-graph. .

"In addition to the above considerations, postulated leakage >

~

through the vacuum breaker to the suppression chamber air space could result in a partial bypass of pressure suppression in the event of a LOCA or a small or intermediate steam leak. This effect could potentially result in exceeding containment design pressure. As a result of the leakage potential, the containment response has been analyzed for a number of postulated conditions.

It was found that the maximum allowabic bypass area for any postu-lated break size was equivalent to a six-inch diameter orifice.1/

This bypass corresponds to a 3/4 inch opening of any one valve or 1/ Report on Torus to Drywell Vacuum Breaker Tests and Modifications for Monticello Nuclear Generating Plant, dated March 12, 1973, autunitted to Mr. D J Skovholt, AEC-DL, from Mr. L 0 Mayer, NSP.

1 EXillBIT A 1/8 inch opening for all ten volves, measured at the bottom of the disc. The position indica'. ion system is designed to detect closure within 1/8" at the bot tom of the disc.

At each refueling outage and following any significant maintenance on the vacuum breaker valves, positive seating of the vacuum breakers will be verified by leak test. The Icak test is conser-vatively designed to demonstrate that leakage is less than that equivalent to leakage through a one-inch orifice tditch is about

37. of the maximum allowable. This test is planned to establish a baseline for valve performance at the start of each operating cycle ~ and to ensure that vacuum breakers are maintained as nearly as possible to their design condition. This test is not planned to serve as a limiting condition for operation.

During reactor operation, an exercise test of the vacuum breakers will be conducted monthly. This test will verify that disc travel is unobstructed and will provide verification that the valves are closing fully, through the position indication system. If one or more of the vacuum breakers does not seat fully as determined from the indicating system, a leak test will be conducted to veri-fy that leakage is within the maximum allowable. Since the extreme lower ILnit of switch detection capability is approximately 1/16",

the planned test is designed to strike a balance between the detec-tion switch capability to verify closure and the maximum allowable leak rate. A special test was performed to establish the basis for this limiting condition. During the first refueling outage all ten vacuum breakers were shimmed 1/16" open at the bottom of the disc. The bypass area associated with the shimming corre-sponded to 50% of the maximum allowable l/ The results of this test are shown in Figure 3.7.1, When a dryvell-suppression chamber vacuum breaker valve is exercised through an opening-clodag cycle, the position indicating lights at the remote test paneb are designed to function as follows:

Full Closed 2 Green - La 2 Red - Off Intermediate Position 2 Green - Off 2 Red -

Off Full Open 2 Green - Off 2 Red - On The remote test panel consists of a push button to actuate the air cylinder for testing, two red lights, and two green lights for each of the ten valves. There are four independent limit switches on each valve. The two switches controlling the green lights are

, ., m O EXIIIBIT A o '

adjusted to provide an indication of disc opening of less than 1/8" at tbs bottom of the disc. The two switches controlling the red 1.;hu are adjusted to provide indication of the. disc very near the full open pv;iLion.

Operability of a vacuum breaker valve and the four assdc'inted indicating light circuits shall be established by cycling the valve. The sequence of the indicating lights will be observed to be that previously described. If both gre.en light circuits are inoperable, the valve shall be considered inoperable and a pressure test is required immediately and upon indication of subsequent operation. If both red light circuits are inopera-ble, the valve shall be considered inoperable, however, no pressure test is required if positive closure indication is present."

REASON FOR CHANGC Experience with the pressure suppression chamber to drywell vacuust breakers has indicated a need for an augmented surveillance program and increased survelliance frequency. To meet this indicated need, the above changes are proposed to enhance reliability to a level commensurate with,other safeguard systems. These changes are intended to satisfy conce'rns'in connection with overall containment integrity drawn from licensing 'con-siderations regarding the vacuum relief system. ,[

s A ,,.[' 4 4G k*t h tvs** l N* /

A i

Gi% Ode '

R, e a

,(

G:0 a

-g.,

w ,.

• ?' $ i

. .. - . ?, ..

O

,'L7:ycyu qm';-,;6 e s ,

• af {$ f$f ']'

W$'d  : a

, j@

'q f  ?,Ji -

ffb gr; 3 "Q. Wr a:a >.