ML20058L341
| ML20058L341 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 02/04/1977 |
| From: | Goller K Office of Nuclear Reactor Regulation |
| To: | Mayer L NORTHERN STATES POWER CO. |
| References | |
| NUDOCS 9105140470 | |
| Download: ML20058L341 (4) | |
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Docket No. 50-263 i
Worthern States Power Company ATTN: Mr. L. O. Mayer, Manager Nuclear Support Services FEB 0 41977 l
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414 Nicollet Hall - 8th Floor tiinneapolis, Minnesota 55401 Gentlemen:
RE: M0!JTICELLO NUCLEAP. THEP.ATING PLANT l
l' Ve have completed our preliminary review of the infomation you submitted on Novenber 5,1976, regardino the instrrientation systems available at your facility to monitor drywell to torus dif ferential pressure (AP) and torus water level. This infomation was provided in response to l
t our letter dated October 4,1976, rebarding Technical Specification requirenents associated with the tiark I Containr!ent Short Term Prograri Plant Unique Analyses.
Based on our review of the infomaticn provided in your response and your existing Technical Specification requirements for instrumentation systens which could be used to monitor drywell to torus AP and torus water level, we have detemined that your Technical Specifications should be revised to incorporate instrumentation system requirements which meet the NRC staff technical position detailed in the enclosure. Consequently, you are requested to provide the following infomation and corimitments l
within 20 days of receipt of this letter:
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Your commitnent to install instrumentation systens to rionitor drywell to torus a P and torus water level which rieet the c:ininun j
reoutrecents of the enclosed NRC staff technical position, D.
Your schecule for completion of the installation ni such systems;
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Your commitment to request appropriate Technical Specification l
changes relating to this instrumentation fullowino installation.
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NRC FOR.M 318 (9 76) NRCM 0240 W un s. oovanuusnv esiswrisse orrecan sert-enM 9105140470 770204 5
h' O 4 577 Northern States Power Company
- l Installation of the above-mentioned instrumentation systems and your request for appropriate Technical Specification changes should be accomplished in an expeditious manner but no later than April 15, 1977.
Orbin 1 rimed by:
Karl R."Coller, Assistant Director for Operatina Reactors Division of Operating Reactors
Enclosure:
I NRC Staff Technical Position l
9,w/ enclosure-See next page
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Northern States Power Company.
.cc w/ enclosure:
Gerald Charnoff, Esquire Shaw, Pittman, Potts and Trowbridge 1800 M Street, N. W.
Washington, D. C.
20036 Arthur Renquist, Esquire Vice President - Law Northern States Power Company 414 Nicollet Mall Minneapolis, Minnesota 55401 Howard J. Vogel, Esquire Legal Counsel 2750 Dean Parkway Minneapolis, Minnesota 55416 Mr. Steve J. Gadler 2120 Carter Avenue St. Paul, Minnesota 55108 Mr. Kenneth Dzugan Environmental Planning Consultant Office of City Planner Grace Building 421 Wabasha Street St. Paul, Minnesota 55102 Sandrr, C. Gardebring, Esquire Spes sal Assistant Attorney General Minnesota Pollution Control Agency 1935 W. County Road B2 Roseville, Minnesota 55113 Anthony Z. Roisman, Esquire Roisman, Kessler and Cashdan 102515th Street, N. W., 5th Floor Washington, D. C.
20005 The Environmental Conservation Library Minneapolis Public Library 300 Nicollet Mall Minneapolis, Minnesota 55401
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j ENCLOSURE 1 i
WRC Staff Technical Position On Instrumentation Systems to Monitor Torus to Drywell Differential Pressure and Torus Water Level In consideration of the significance of drywell to torus differential pressure (gP) control and torus water level control to the results of the Mark I Contaiment Short Term Progran Plant Unique Analyses, we have concluded that a mininum of two narrow range instrument channels should be provided to ruonitor each of these plant parameters.
Operational experience indicates that pressure transducers tend to drift and water level indicators tend to stick; these observations, together with standard instrument calioration frequency requirements, form the basis for our requirenents for a minimum of two instrument channels per i
parameter.
The significance of variations in drywell to torus AP and torus water level and the nagnitude of the LOCA-related hydroaynamic loads on torus support systems forms the basis for our requirement f or narrow range instrumentation to accurately neasure these parameters. The error-band of the instrumentation used to moniter the drywell-wetwell differential pressure ar.d the torus water level should be small in comparison to the absolute value of the parameter being measured. Based on the load sensitivity curves presented in Addendum 2 to the Mark I Containment Short Term Program Final Report and typical instrunent accuracies, we conclude that the error in the AP measurement should be no greater than +0.1 psid and that the error in the torus water level measureuent should be no greater than 10% of the difference between the r,aximum and minimum torus water level (i.e., if the dif ference between maximum level and mininun level = 4", then the instrument error should be <.4*).
The Technical Specifications for each Mark I BW9 facility (except Brunswick Units Hos.1 and 2) should include requirenents consistent with this position. Action to be taken in the event that one or both of the instrument channels is out of service should be consistent with other reoutrements for surveillance instrunentation.
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