ML20211D006
| ML20211D006 | |
| Person / Time | |
|---|---|
| Site: | La Crosse File:Dairyland Power Cooperative icon.png |
| Issue date: | 10/10/1986 |
| From: | Taylor J DAIRYLAND POWER COOPERATIVE |
| To: | Zwolinski J Office of Nuclear Reactor Regulation |
| References | |
| LAC-11884, NUDOCS 8610220077 | |
| Download: ML20211D006 (5) | |
Text
D DA/RYLAND hh[4/[ COOPERATIVE
- P O box 817
- 2615 EAST AVE. SO LA CR (608) 788-4000 JAMES W. TAYLOR G:neral Manager October 10, 1986-In reply, please refer to LAC-Il884 DOCKET NO. 50-409 Mr. John A. Zwolinski, Director BWR Project Directorate #1 Division of BWR Licensing U.S. Nuclear Regulatory Commission Washington, DC 20555
SUBJECT:
DAIRYLAND POWER COOPERATIVE LA CROSSE BOILING WATER REACTOR (LACBWR)
PROVISIONAL OPERATING LICENSE NO. DPR-45 REPLACEMENT NUCLEAR INSTRUMENTATION
REFERENCES:
(1) DPC Letter, Taylor to Zwo11nski, LAC-Il402, dated February 6, 1986.
(2) The Nuclear Measurement Analysis and Control Logarithmic Radiation Monitor (NUMAC-LRM),
NEDO 30883, Class 1, April 1985.
Dear Mr. Zwolinski:
i In Reference 1, we requested that you provide a generic review of "The Nuclear Measurement Analysis and Control Radiation Monitor (NUMAC-LRM)" because we were going to replace the aging instruments that presently monitor and provide shutdown functions for the LACBWR nuc' lear reactor with NUMAC instruments from General Electric Company.
The present nuclear instrument system is described in LACBWR FSAR Section 7.2.
The system consists of eight information channels in three functional divisions: source, intermediate, and power ranges.
Two source range channels monitor the first five decades of reactor operation; two intermediate range channels cover seven decades of operation to approximately 10% of full power; two wide range power channels cover eight decades of operation to approximately 150% of full power; and two standard power range channels monitor the last two decades of power operation to approximately 150% of full power.
The entire system is going to be replaced by six NUMAC instruments providing at least the same range of monitoring and all of the functions of the present system. There will be two source range channels covering seven decades of reactor operation, (one decade below and one decade above the present source instrument range), and four wide range channels covering nine decades of dc0j WPl.3.7 8610220077 861010 PDR ADOCK 05000409 Io P
Mr. John A. Zwolinski, Director October 10, 1986 BWR Project Directorate #1 LAC-Il884 reactor power from approximately the top two decades on the source range channels to 150% of full reactor power.
We will replace all the monitoring instruments with NUMAC instruments.
The proportional counters (detectors) for the two source range channels will be the same. However, the cables and connectors between the detectors and the chassis will be replaced only for the purpose of updating the system. The outputs from the NUMAC source range channels will be identical to those presently used.
The present system of intermediate range channels, wid. range channels and standard power range channels will be replaced with four wide range (NUMAC-WRM) channels which will provide all the monitoring and protection functions presently used plus some additional features.
The compensated ion a
chambers for the intermediate and wide range channels will be used as the detectors for the four NUMAC-WhM channels.
The cables and connectors will be replaced in the interest of updating the system.
Each NUMAC-WRM incorporates a form of the period (rate of change of flux) scram up to approximately 1% full power.
Each NUMAC-WRM has the inputs necessary for and computes the reactor power-to-recirculation flow relationship from 1% reactor power up to full power.
Each NUMAC-WRM has the inputs of steam flow, steam pressure and feedwater temperature in order to compute a heat balance which in turn is used to compensate the neutron flux signal for its nonlinearity, (the present Automatic Gain Compensation System).
Therefore, each NUMAC-WRM has output trips of high flux, abnormal power to flow relationship, and below 1% power, a period (margin) trip.
Each of these parameters also has an alarm output, prior to the trip setting. The output trips from the four NQ4AC-WRM instruments are arranged in the (external) scram system in 2-of-4 logic.
The 2-of-4 logic in the scram system for the margin (period) trip and the abnormal power-to-flow relationship is preferred to the present 1-of-2 logic to reduce the potential of challenges to the shutdown system for false trips.
The 2-of-4 logic for high flux trips is not dif ferent from the present system.
Since Reference 2 was issued as a Licensing Topical Report, there have been a number of improvements and firm design selections on NUMAC instruments for LACBWR. The NUMAC instruments for LACBWR have some specific design features incorporated in them that are dif ferent from those of Reference 2.
Those i
features are enumerated below, utilizing the same paragraph numbering as in Reference 2.
3.1.1 There is no automatic ranging in the LACHWR NUMAC. The present LACBWR wide range instruments have manual range changes. The NUMAC Wide Range Monitor (WRM) displays on a bar graph and an analog meter the full range of the instrument, and continuously displays the numerical value of the flux level.
3.1.4 LACBWR's Source Range NUMAC incorporates a 64-channel spectrum analyzer to generate a curve of the pulse heights from the detector to aid in WPl.3.7.
Mr. John A. Zwolinski, Director October 10, 1986 BWR Project Directorate #1 LAC-11884 the setting of the discriminator window.
The discriminator module receives pulses from the detector pre-amplifier and counts pulses only within the (adjustable) window. Neutron counting is over the range of
.1 to IE6 counts per second.
LACSWR's Wide Range Monitor has an 11-channel isolated analog input module to condition the incoming plant process signals. The incoming neutron signal from the ion chamber detector enters the femtoammeter module.
3.1.5 The detector' power supply is a dual power supply; with a range of
+100 to +1400 volts and -100 to -1400 volts.
3.1.6 The LACBWR NUMAC analog outputs are used to drive recorders and meters. The external relays are mounted on the NUMAC chassis and are separate Form C relays whose contacts are in separate reactor protection strings. The Form C relay contacts are brought out from the d rawer in separate receptacles.
3.3.
When not in the Operate mode, the display stays on continuously.
For LACBWR NUMAC, when in Operate mode, the f ront panel is in " Display Only" mode, but there are alternate displays which may be selected and 30 not affect the safety-related functions into or from the drawer.
In thi LACHWR Source Range Monitor there are 6 alternate displays in the Operate mode and for the WRM there are 10.
4.1 If the Self Test System (STS) detects a failure of a safety-related function, it causes a trip, the display comes on and signals a plant alarm. The STS also detects failures that are not directly safety elated, and these failures energize the display and plant alarm only.
4.2 The LACBWR NUMAC has dual LVPS. Their outputs are " auctioned" and the failure of one does not cause a drawer failure, only a STS indication.
Add 4.4.7.3 NUREG-0700 Review The front panel design of the generic NUMAC instrument was reviewed against the provisions of NUREG-0700, " Guideline for Control Room Design Reviews",
September 1981, and specifically against the provisions of Section 6, " Control Room Human Factors Guidelines."
The NUMAC design meets all guidelines for layout, placement and spacing of push buttons, and character height on the display. Two minor guideline deviations exist as described below:
a.
The guideline for distance of key travel is waived so that membrane switches can be used in place of spring loaded push buttons to avoid the entrance of dirt. This deviation is acceptable because tactile and audio feedback have been employed and software is so arranged that any data / settings entered are echoed back on the display.
WPl.3.7 -
Mr. John A. Zwolinski, Director October 10, 1986 BWR Project Directorate #1 LAC-11884 b.
The second deviation relates to the numeric keyboard.
NUMAC employs an augmented calculator style keyboard.
In Exhibit 6.7-2(b) of NUREG-0700, the digit "zero" is placed beneath the digit "two".
In NUMAC, it is placed beneath the digit "one."
This minor deviation is acceptable. Operation of the keyboard in the laboratory, in QA, and during environmental qualification has shown this not to cause confusion or otherwise be a problem.
It is concluded that the NUMAC front panel design meets the guidelines set forth in NUREG-0700.
4.5.1.2 LACBWR NQiAC does not use auto ranging; a better description of the scales and displays follows: The input signal for the SRM is from the-proportional counter through an external pre-amplifier where pulse shaping and mnplification is done and into the drawer into the discriminator. The discriminator has independent top and bottom I
range adjustments in order to discriminate against gamma and noise input pulses.
The measured signal is in counts per second (cps).
The count rate is displayed to 3 significant figures.
Scientific (exponent base 10) notation is used. A graphic representation of count rate and period is on the front panel screen in addition to numeric display of each.
Additionally, analog meters of cps and period are continuously indicated external to the drawer.
4.5.1.4 Speed of response of the SRM varies with the count rate. The time constant of response varies inversely with the count rate.
4.5.2 The trip outputs of a channel are tailored to LACBWR.
There are two scram trips f rom the WRM to provide independent trips to the reactor protective system strings.
Other trips are used for the same functions as presently used in LACBWR.
4.5.2.9 Interruption of power: Any parameters calculated or entered during calibratior. that are used to discriminate pulses, determine levels, trip conditions, or analog outputs are stored in non-volatile memory (e.q. EAROM) to guard against the ef fects of power interruption.
Whenever power is removed, an INOP trip indication is provided. Upon resumption of power, the instrument reverts
- the trip settings that existed immediately before interruption of te r. Trip status will then be recomputed and the output circuits snt accordingly and without regard to hysteresis conditions existing before interruption.
4.5.2.10.c Pa rame te r settings can also be displayed on demand.
4.5.4.2 No process computer output is specified for LACBWR, however, recorder outputs and analog meters are utilized.
WPl.3.7 Mr. John A. Zwolinski, Director October 10, 1986 BWR Project Directorate #1 LAC-11884 4.6.4.2 Additional requests on user demand are:
b.
accepting user selected values for parameters 4.9.7 The front panel display via LACBWR sof tware can be called upon for up to 46 different screens for calibrating and/or interrogating the input or outputs of the drawer.
The SRM is similar, but with fewer screens.
The above information is supplied as " differences" to Reference 2 the NUMAC instrumentation provided LACBWR.
If you have any questions, please contact us.
Sincerely,
/
JWT: HAT:sks cc:
Mr. James G. Keppler, Regional Administrator Mr. John Stang, LAC 9WR Project Manager NRC Resident Inspector WPl.3.7