ML20127G591

Grants Mods Discussed in 740123 Submittal Re Equilibrium Core Scram Reactivity Insertion Characteristics.Meeting Summary & SE Encl

ML20127G591
Person / Time
Site:	Monticello
Issue date:	03/14/1974
From:	Skovholt D US ATOMIC ENERGY COMMISSION (AEC)
To:	Mayer L NORTHERN STATES POWER CO.
Shared Package
ML20127G595	List: ML20127G591 ML20127G609 ML20127G621
References
NUDOCS 9211170387
Download: ML20127G591 (3)

Text

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Docket No. 50-263 P

Horthern States Power Company ATTH: Mr. L. O. Mayer. Director of Nuclear Support Services 414 Nicollet Mall License No. DPR-22 i i

Minneapolis, Minnesota 55401 Approval of Plant Hodification for Gentlemen. Fuel Cycle 3 lc have reviewed your submittal dated January 23, 1974, entitled .

Permanent Plant Changes to Accommodate Equilibrium Core Scram Reac- .

tivity Insertion Characteristics". The proposed plant changes described involve.

1. re:aoval of tne four existing spring-loaded safety valves and installation of at least two new safety / relief valves in addition to the four safety / relief valves installed prior to the initial plant startup (total of six safety / relief valves) .

2. installation of a conceptually new prompt relief trip (PRT) system to open as uany as all six safety / relief valves, before pressure self-actuation, by signal from fast closure of main turbine control valves or closure of the main turbine stop valves.

3. Installation of four new blowdown lines between the two new safety / relief valves that are to be connected to the PRT system and two other locations where safety / relief valves can be installed and the torus suppression pool.

You have noted that:

1. The purpose of the PRT system is to compensate for equilibrium core scram reactivity insertion functions by reducing the peak pressure and fuel thermal effects resulting from pressurization caused by abnormal operational transients.

2. The PRT is designed to anticipate the pressure transient resulting from a turbine or generator trip with the assumed failure of the turbine bypaso valves to open, and t

9211170387 740314

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PDR ADOCK 05000263 P PDR

r MAR 141974 Worthern States Power company l 4'

3. Mie PRT is not concidered an overpressure protection function, d,

k's informed your representatives by telephone within two weeks af ter 1 .

J receiving your submittal that we could not complete our evaluation of your analytical methods or the PRI system that you have proposed in time to approve the planned modifications before they are completed.

As a result, we met in Bethesda(1) on February 20 and 21,1974, with 1 j' HSP representatives to clarify certain aspects of the analytical results included in your January 23, 1974 submittal and to discuss our additional interim requirements that must be satisfied to allow plant modifications to proceed on schedule.

On the basis of your submittal and the understandings reached during j the meeting, namely that:

i 1. Existing total pressure relief capacity through safety and/or safety / relief valves will be maintained, and

2. New scram reactivity curves will be provided with the associated analysis to permit reactor operation at rated power level for a specified period at the beginning of fuel cycle 3 without dependance on the PRT or reduction in conservatism factors,

' we have concluded that you may proceed with the plant modificatiots as planned and in the manner you have described prior to the completion

of our review of the chas2ges proposed by your January 23, 1974 submittal .

Since the plant will be shut down and depressurized for simultaneoua refueling, there are no significant hazards considerations and there is reasonable assurance that the health and safety of the public will not l

be endangered by the modifications as you have described them.

i Further analysis must be performed by USP and submitted for our approval

! along with proposed technical specification changes prior to startup of Honticello with the modifications in place. A copy of the meeting minutes

._ and safety evaluation are included for your information as Attachments 1 and 2.

l.

i Sincerely, oenal E.tsai by -

D. L reevholt

! Donald J. Skovholt Assistant Director for Operating Reactora Directorate of Licensing Luu- m. and w - um e r "T1T virectentiE'uunninT1'dnurea wf Martingm-Februarr20-*2irit74 l

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l 1 Enclosures .

1. Heating Minutes

2. Safety Evaluation

! cc w/ enclosures:

i Arthur Renquist, Esquire Anthony Z. Roissan, Esquiro Vice President - Law Berlin, Roisman and Kessler

'm Northern States Power Co:gany 1712 N S tree t , H. W.

414 .iicollet Mall Washington, D. C. 20036 Minneapolis, Minnesota 55401 Geraid Charnoff Sla,d , Pittman, Potts, Trowbridge 6 Madden '

910 - 17th Street, N. V.

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Washington, D. C. 20006 Distribution .

g eket File  ;

Howard J. Vogel, Esquire AEC PDR Knittle & Vogel Local PDR

' 1154 Cast Grain Exchange Building y 2" dig 412 South 4th Street Branch Reading Minneapolis, Minnesota 55415 JRBuchanan, ORNL l

DJSkovholt, L:0R 2

Steve Gadler, P. E. TJCarter, L:0R 2120 Carter Avenue ACRS (16) 4 St. Paul, Minnesota 55108 R0 (3) i OGC I Mr. Daniel L. Ficker DLZiemann, L 0RB #2 Assistant City Attorney JJShea, L:0RB #2 4 647 City 11all RMDiggs, L 0RB #2

, St. Paul, Minnesota 55102 SVarga, L:0RB #2 NDube L:0PS Warren R. Lawson, H. D. }Uinks, DRA Secretary 6 Executive Officer VStello, L:RS l ~

l State Department of 11ealth 717 Delaware Street, S. E.

{ ejaL l Minneapolis ,111nnesota 55440 k.c swh&

i Sandra S. Cardebring, Esquire  % ggd Minnesota Pollution Control Agency .

h, Kx 1935 W. County Road B2 Roseville, Minnesota 55113 Environmental Library of Minnesota

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