ML20151J318
| ML20151J318 | |
| Person / Time | |
|---|---|
| Site: | 05000054 |
| Issue date: | 07/21/1988 |
| From: | Mary Johnson CINTICHEM, INC. |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| Shared Package | |
| ML20151J324 | List: |
| References | |
| NUDOCS 8808020224 | |
| Download: ML20151J318 (4) | |
Text
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CINTICHEM, INC.
l a wholly owred subsdor'y of Medi-Physics, Inc. p.o eax eso. Tuxeoo. NEW YoAK 10907 19111351-2131 J
O July 21, 1988 i
Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 SLBJECT: AENDENT TO TE04NICAL SPECIFICATIONS FOR DOCKTET 50-54 LIGNSE R-81 6
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l ENQ.05URES: 1. Check #53876 for $150.00
- 2. Block diagram of the Log-N System.
- 3. Proposed Changes to Technical Specifications 3.3.4 and 5.2.2.
- l. 4 Proposed Qiange to Technical Specification 3.5.1.
4 Dear Sirst I
Cl nti chem, Inc. requests two Technical Specification changes to allow the 3 placement of our present Log-N and period ampilfler (Honeywell Model 4639-2-4) with a new amplifier (Keithl ey Model 25012A). In addition we are
,! esquesting a change of reference numbers for Technical Specification 3.5.1.
l The Log-N and period empilfler is a part of the reactor control system and is f unctionally divided into two sections: a Log-N section and a period section.
j The Log-N section receives a current input f rom an Ionization chamber and j produces a voltage proportional to the logarithm of the input current. The Log-N output signal is a measure of reactor power and is indicated on a meter and recorder calibrated in percent powe r. The period section derives the reactor period (the time it takes f or reactor power to change by a f actor of e) f rom the rate of power leywl change. The period is constantly measured and displayed on a setor and recorder calibrated in seconds. The only control f unction prwided by the ampilfler is a three second period scram signal to tr.e saf ety system. The other Intermediate range control and inhibit actions (V IZ., bypassing of count rate channel functions, bypassing of flew and flapper scrams) come frce a chart recorder which is driven by the empilfler.
A block diagram of the Log-N channel is included.
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The reasons f or the proposed change to this system are as f ollows. The Honeywel l ampilfler is a high vol tage, high power consumption tube type 1 amplifier that has been in service at our reactor since Initial criticality :
(1961). It has a total range of 5 watts (.0001%) to 15 M watts (300%). The !
tubes used for its operation are subject to noise and drifting and are boccaing increasingly unevallable. The converter used in the period section is an electrcnochanical type which is also subject to noise. This system is !
responsible f or numerous shutdowns annually. They are classified as False Period Scrams due to the fact that, after all reactor parameters are ev al uated, the scram was determined to have been caused by noise or i instabil ity in the Log-N channel. These f also scrams have occurred at an :
everage of 12 per year over the lest 10 years, with 27 occurring to date in i 1988. Of more concern than the shutdown itsel f is the f act that, if these ,
scrams occur frequently, the control roce operators could become used to this i type of scrm action. This could lead to a situation in which a shutdown might be readily attributed to Log-N noise when, in fact, a serious problem ,
might be present or developing.
For these reasons, a new Kelthiey model 25012A Log-N and perlod ampiIfler was purchased and has been undergoing testing and evaluation. This ampilf ter has a total range of .1 watt (.000002%) to 10 M watts (200%). It is a Ice vol tage, low power all solid state unit that has a very reliable operating history at other research reactors. It's solid state components are readily av ail abl e. This unit provides a f ast three second period scram as does the ol d Log-N ampt If ler. The KeIthley unit elso incorporatos a siow seren backup ;
of the f ast scram as does the Honeywell unit. Comparison tests of the f ast '
scram function in the Honeywell vs. the Keithley amps have yielded a 135 ;
f aster scram time with the Kelthley am p. This scram i s not a Technical i Specification limiting saf ety system setting. Al so, the safety analysis in ;
the S. A.R. does not concern itsel f with a f ast period scram, using Instead the l 150% (7.5 *) high flux scram f rom the saf ety channels. [
Qiangeover to the Keithley Log-N will involve two changes to the Technical i Spect f Ications. The present Technical Specifications concerning the Log-N and i proposed changes are included as Enclosure 3 These changes involve two Log-N l speci f ications: 1. the reliable range of f rom .001% to 3005 (of 5 m), and 2. )
the provision to supply a bucking current. The Log-N has no control f unction ,
above a 1255 rod reverse setpoint of f the recorder. The saf ety charnels scram i at $ 150%. Therefore, it was f elt that the new Log-N's wider range could be i expanded even more at the lower end by limiting the upper range to 2005. This !
provides more rellable tracking in the low power ranges when it is needed, !
during reactor shutdown and startup. This expanded lower range also oddresses l the lack of a need f or a small adjustable buck'ng current during startup. !
Af ter an extended shutdown the Honeywell Log-N will be of f scale and needs a l bucking current to bring it on scale before a startup to prevent a f alse l period s cr are. This current is then returned to zero once cri ti cal ity is [
achieved. This feature will not be needed with the Keithley Log-N because it l will still be on scale afier an extended shutdown. ;
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In summary, the proposed change to the Log-N system involved replacing the ampiifIer wIth a newer, alI solid state instrument that has approximately a two decade larger operating range and of fers more stable power and period monitori ng. The Honeywell amplifiers will be retained as omsrgency backup empilf ters. Therefore, procwdural and physical changes will be made to accommodate both model ampilflers to f acilitate use of either in the Log-N ch annel .
Lastly, in accordance with a recommendation from NRC I nspectors, it is requested that the reference f or Section 3.5.1 (Enclosure 4) be changed to Section 3.4 as this is the more accurate ref erence number.
Sincerely,
'w+m Michael 0. J on
- Rear: tor Superv sor j N0J/10E Enclosures cc U. S. Nuclear Regulatory Commission Director, Division of Project and Resident Programs
- King of Prussia, PA 19406 U. S. Nuct eer Regul story Commt sst on Attention
- Mr. Ted Michaels Mall Stop 11H3 Of fIce of Nuclear Reactor Regulatton d O! vision of Licensing Washington, DC 20555 J
1 Mr. Laurence Rossbach NRC Resident inspecior P.O. Box 38 Buchanan, NY 10511 1
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ENQ.0S0RE 2 LOG-N OiANNEL BLOCK DI AGRAM Log-N Recorder ClO i Log-N and _l Periodknpl Log-N Period l Recorder HV Comp l Compensated lon Fast Period Slanal > To Safety Chamber Power System Supply l l
MDJ/10E 1
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