ML20207J803
| ML20207J803 | |
| Person / Time | |
|---|---|
| Site: | La Crosse File:Dairyland Power Cooperative icon.png |
| Issue date: | 12/19/1986 |
| From: | Taylor J DAIRYLAND POWER COOPERATIVE |
| To: | Zwolinski J Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML19292G558 | List: |
| References | |
| LAC-12019, NUDOCS 8701080601 | |
| Download: ML20207J803 (8) | |
Text
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i g-D DA/RYLAND hhh[ COOPERATlVE e O Box 8ir 26is EAST AVE SO LA CROSSE. W (608) 788-4000 JAMES W. TAYLOR General Manager December 19, 1986 In reply, please refer to LAC-12019 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 APPLICATION FOR AMENDMENT TO LICENSE
REFERENCES:
(1) 10 CFR 50, Section 50.90 (2) DPC letter, Taylor to Zwolinski, LAC-11402, dated February 6, 1986.
(3) The Nuclear Measurement Analysis and Control Logarithmic Radiation Monitor (NUMAC-LRM),
NEDO 30883, Class 1, April 1985.
(4) DPC letter, Taylor to Zwolinski, LAC-Il884, dated October 10, 1986.
Centlemen:
In accordance with Reference 1, we are submitting three originals and 37 copies of a request for a change to Appendix A, Technical Specification of I subject license.
0-Jg This request is in connection with updating the Nuclear Instrumentation for w o n. the LACBWR.
"8 g In Reference 2, we requested that you provide a generic review of "The Nuclear Measurement Analysis and Control Radiation Monitor (NUMAC-LRM)" because we "h
o were going to replace the aging instruments that presently monitor and provide
-Qin <
shutdown functions for the LACBWR nuclear reactor with NUMAC instruments from General Electric Company. Reference 4 supplied details of how the NUMAC-LRM O. specifically applied to LACBWR.
R5 (D a.a. 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 are e . O h 0' WPl.3.7 / / M86 3jp anc
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' Mr. John Zwolinrki, Director December 19, 1986 BWR Project Directorate #1 LAC-12019 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 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 I outputs from the NUMAC source range channels will be identical to those presently used.
The present system of intermediate range channels, wide range channels and standard power range channels will be replaced with four wide range (NUMAC-WRM) channels which will provide the equivalent monitoring and protection functions presently used plus some additional features. The compensated ion chambers for the intermediate and wide range channels will be used as the detectors for the four NW4AC-WRM channels. The cables and connectors will be replaced in the interest of updating the system.
Each NUMAC-UF_ incorporates a form of the period (rate of change of flux) scram up to approximately 15% full power. Each NUMAC-WRM has the inputs necessary for and computes the reactor power-to-recirculation flow relationship above approximately 15% reactor power up to full power. Each NuiAC-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 Cain Compensation System). Therefore, each NUMAC-WRM has output trips of high flux, abnormal power to flow relationship, and below 15% power, a margin (period) trip. Each of these parameters also has an alarm output, prior to the trip setting. The output trips from the four NUMAC-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 by false trips.
The 2-of-4 logic for high flux trips is not different from the present system logic above 15% power.
Enclosure A is the relevant pages of the present Technical Specifications.
Enclosure B is the pages after the proposed changes.
WPl.3.7 s Mr. John Zwolin ki, Director December 19, 1986 i BWR Project Directorate #1 LAC-12019 Enclosure C is a document containing information proprietary to General Electric Company. The document is: W.S. Rowe to Group Patent Counsel "INVENTION DISCLOSURE LETTER - GENERAL ELECTRIC TRANSIENT MONITOR (CETRAM)",
dated February 12, 1985. It is requested that you use your best efforts to assure that this document and the information contained therein will not be copied, disclosed or used except for the purpose of evaluating its use in the LACBWR nuclear instrument system without the prior written agreement of the General Electric Company.
The CETRAM is incorporated in each WRM to be installed at LACBWR. Each of the WRM will be able to produce a control rod withdrawal prohibit on an increasing neutron flux transient equivalent to a 15 second period. Each WRM will produce a trip signal if the transient exceeds a period of 3 seconds. This trip is arranged in a 2-of-4 logic to produce a reactor scram. In LACBWR, the rod block and scram trip functions will be bypassed when indicated reactor power exceeds 15%. Enclosure C provides details of the GETRAM.
An explanation of each proposed change to Technical Specifications is included herein.
Delete section 2.8.6. The description of the rod test circuit is in the FSAR, j paragraph 7.2.4, 7.2.8, and 7.4.4. The 7 second trip point and conditions for a rod scram test are not changed.
Delete sections 2.10.1.1, 2.10.1.2, and 2.10.1.3 as these general functions are descriptive of the functions and capabilities of the instrumentation being replaced.
Delete 2.10.2.3. The description of the control rod withdrawal interlock circuit is in the FSAR, paragraphs 7.2.4, 7.2.5, and 7.4.4.
Delete 2.10.2.4. The description of the reactor start interlock circuit is in the FSAR, paragraphs 7.2.4 and 7.4.4.
Delete 2.10.2.5. The description of how the " seal-in" of the reactor start circuit is removed by a full scram is in the the FSAR, paragraph 7.4.4.
Delete 2.10.2.6. The replacement instrumentation does not change the manual scram capability. A description of the manual scram is in the FSAR, paragraph 7.4.15.
Deleto section 2.10.3. The replacement nuclear instrumentation will have 2 channels that will extend to below source level and up to overlap the wide range channels by at least 1/2 decade. The four wide range channels will extcad up to 150% of rated power. The replacement wide range instruments are capable of performing the gain correction on the neutron flux signal developing the reactor power level, and initiating scram actions per Table 1 and provide the same reactor start and rod withdrawal interlock functions as the present instrumentation.
Source range scram actions and interlocks are not changed. The scram actions f rom the four wide range monitors will be arranged in a 2-of-4 logic at all times except when the drawer is placed in test or for maintenance.
WPl.3.7 _ . _ - _ . . . .
December 19, 1986 Mr. John Zwolinski, Director BWR Project Directorate #1 LAC-12019 There are 3 scram functions fron each wide range channel. At all power levels there is a high flux scram set f,120% of rated power. Below 15% rated power (user selectable) there is a form of a rate scram and the control rod withdraw trip interlock.
Each of the four wide range channels incorporates the General Electric designed Transient Monitor (see Appendix C). This circuit provides the rod withdrawal interlock function, the 3 second period scram trip function below 15% rated power, and eliminates manual ranging of the instruments while providing scram protection.
It provides a trip response time which varies inversely with the severity of the transient or accident. For very rapid events response times equal to or shorter than the current instruments are provided. For normal startup power increase rates, the convenience of " hands-of f" operation without a trip is provided. For intermediate rates of increase ranging from those which could damage fuel, to those which are unlikely to affect fuel but represent too rapid a change to be under operator control, the trip response time varies inversely with the rate of increase. During mild transients, such as normal control rod withdrawal, the operator is provided sufficient time to control the event by control rod insertion, preventing a scram.
This trip is identified as a " margin" trip on the instruments. The scale is 100% margin down to 0% margin. Steady state operation gives 100% margin, and increasing power transients reduce the margin to 0%, equivalent to a 3 second period trip point. Rod withdrawal prohibit trip is indicated on the margin Scale Corresponding to a 15 second period.
Above 15% rated power (user selectable) there is a power to recirculation flow comparison and trip if results are unfavorable.
The neutron detectors will still be positioned in six horizontal instrument tubes; source ranges will be 180* apart, and the four wide range detectors located 90' apart.
The gain of each wide range channel is continuously corrected so that the output corresponds to the power level determined by steam flow, when above a minimum flow rate, because the attenuation of the neutron flux at the detectors is a -function of the void content of the water on the periphery of the reactor vessel. Each channel uses inputs of steam flow, steam pressure and feedwater temperature in order to make the flux signal correction.
A detailed description of the replacement instrumentation will be included in the next FSAR update, paragraph 7.2.
Table 4.0.2.2.1-1 is revised to reflect the new scheme of instrumentation, but no change in values is made; however, the trips from the wide range monitors are arranged in 2-of-4 logic external to the chassis.
Item 4 is changed in nomenclature, and the trip set point for high flux is f, 120% of Rated Thermal Power.
WPl.3.7 s
T Mr. John Zwolinski, Director December 19, 1986 BWR Project Directorate #1 LAC-12019 Item 5 and 6a are. combined to reflect the " transient trip" available from all four wide range channels below 15% indicated power.
Item 6b is included in 4 above. Item 6 now reflects that the reactor power-to-forced circulation flow abnormal comparison and trip is made in each wide range channel above 15% reactor power.
Item 8 is replaced by Item 6 above; Item 8 is blank.
Figure 4.0.2.2.1-1 is not changed.
Bases for Section 4.0.2.2 are revised to describe the replacement instrumentation.
Bases for specification 4.2.4.2.2 and 5.2.17.2 are not changed except for correcting a typing error on LCO number.
Section 4.2.6.3 item (3) is deleted since Intermediate Range Channel 3 and 4 are removed. The replacement wide range instruments automatically bypass the rod withdrawal interlock above 15% reactor power.
Sections 4.2.6.4 and 4.2.6.5 are revised to clarify their intentions; as those sections referred to are deleted.
Section 4.2.6.6 is deleted as the requirement is included in specification 4/5.0.2.3.1.
Section 4.2.6.7 is deleted. Technical Specification 4/5.0.2.3.2 specifies operability requirements of the wide range channels. There are three types of trips from each channel which may cause a scram.
(1) Reactor power margin below 15% power.
(2) Power-to-flow above 15% power.
(3) High flux at any reactor power.
! The three trips from the wide range channels which may cause reactor scram are arranged such that they are independently actuated (within a channel), but operate a single output relay. The output relay contacts are arranged in a p 2-of-4 logic in external dual scram strings. Placing a channel in test status l does not place the channel in a tripped condition such that it takes 2 of the l remaining 3 channels to trip to cause a reactor scram. This arrangement is l
selected to reduce challenges to the safety system by preventing reactor scrams from single failures.
i The rod withdrawal prohibit trip is in a 1-of-4 logic from the wide range monitors. A control rod withdraw is prohibited if any one channel is placed in
- inoperable status below 15% reactor power, however, there is no ef fect on rod l withdrawal above 15% reactor power, whether the channel is in inoperable status or not.
WPl.3.7 i l
.1 Mr. John Zwolinski, Director ' December 19, 1986 BWR Project Directorate #1 LAC-12019 Page 5-7, items 3 and 5 and page 5-8 items 6 and 7 are deleted as the surveillance requirements in new specification 5.0.2.3.
Page 5-11 items 1 and 2 and page 5-12 items 4 and 5 are revised to indicate the provisions of the replacement instrumentation.
t In summary, even though the proposed Technical Specification changes look extensive, all the changes are administrative because:
(1) The same range of power operation (neutron flux) is monitored.
(2) The interlock and prohibit systems are the same.
(3) The trip outputs to the redundant scram strings are arranged in 2-of-4 logic over the entire wide range of power operation.
(4) The non-linearity of the neutron flux signal has the same
- corrections applied (automatic gain system).
(5) The manual ranging of the trips and indication from the old wide range instruments is eliminated by the automatic electronic surveillance system (General Electric Transient Monitor).
We have reviewed the hazards considerations referenced in 10 CFR 50.92 and have determined that no significant hazards result from this proposed amendment because it does not:
(1) Involve a significant increase in the probability or consequences of an accident previously evaluated. The replacement source range instruments provide the exact same interlocks and protection functions at the same values, i.e. reactor start interlock will still require the determination that the system is detecting and counting core neutrons above system and gamma " noise" level in order to have a reactor start permit. Also both source ranges must be operable in order to obtain the reactor start permit.
Also, either of the replacement source range channels will develop a 7-second period trip, to prohibit control rod withdrawal when the reactor is in startup mode. When the reactor is in control rod test mode, the 7-second period trip will produce a rod scram signal.
- The replacement wide range channels provide a range of indication and protection equivalent to the present instrumentation; i.e.
overlaps the source range on the low end and up to 150% power on upper end. The replacement instrumentation incorporates the flux compensation subsystem, utilizing the same process parameters that are presently used in the Automatic Gain System. The wide range instruments incorporate a high flux trip (120%) that is always available to terminate a transient originating from any reactor power level. This trip is arranged in a 2-of-4 logic to produce a reactor scram, not unlike the present system when above 15% reactor power.
WPl.3.7 _-
5 Mr. John Zwolinski, Director December 19, 1986 BWR Project Directorate #1 LAC-12019
^
The reactor power to recirculation flow comparison utilizes the same parameters and provides a trip at the same value from each channel.
The computation is made only in the power range, i.e. above approximately 15% power up to full power. The trips of abnormal power to flow are arranged in 2-of-4 logic.
The rate of flux change trip from each channel is set at the same value as the present instrumentation, and is active over essentially the same range, namely up to 15% power. The abnormal rate trips are arranged in 2-of-4 logic.
The 2-of-4 logic will reduce the challenges to the plant safety systems in the event of single failures of equipment or components and still provide adequate protection in the event of a reactor transient, thus increasing the margin of safety.
(2) Create the possibility of a new or different kind of accident from any accident previously evaluated because the range of monitoring is the same, the parameters monitored are the same, and the trip values are the same as the present instrumentation.
(3) Involve a significant reduction in a margin of safety because:
(a) the replacement instrumentation is fabricated to todays standards, a major improvement in reliability over the present instrumentation;.
(b) the new instrumentation has internal redundancy and self testing ability; (c) the increased use of 2-of-4 scram logic and; (d) the elimination of manual ranging of the monitoring instrumentation all_ help to increase the margin of safety in responding to any, reactor transient.
The substitution of the high flux trip on discrete ranges of the wide range instruments with the GETRAM type of trip will not involve a significant reduction in the margin of safety because the GETRAM design will cause a trip at a low power during a rapid power increase, while eliminating the manual ranging, a contribution to unnecessary reactor scrams.
The proposal of not inserting a trip in the scram string when testing or maintenance is being performed on a wide range monitor will not involve a significant reduction in the margin of safety because its effect will be to reduce the scram logic from 2-of-4 to 2-of-3 if a channel is out of service. A scram would still occur if there is a failure of one of three remaining instruments coincident with a high power condition. The proposed Action Statement will regiure reactor shutdown if two channels are inoperable.
WPl.3.7 Mr. John Zwolin2ki, Director Decembsr 19, 1986 BWR Project Directorate #1 LAC-12019 An application fee of_$150 will be forthcoming in regard to this license amendment request.-
If there are any questions, please contact us.
Sincerely, JWT: HAT:sks
. Enclosures cc: Mr. Roby Bevan, LACBWR Project Manager Mr. James G. Keppler, Region III NRC Pasident Intpector Mr. L. L. Smith, Director of Electric and Water Bureau
, Wisconsin Public Service Commission P. O. Box 7854 Madison, WI 53707 STATE OF WISCONSIN )
)
COUNTY OF LA CROSSE )
Personally came before me this 22' day of M A-r> , 1986, the above named, James W. Taylor, to me known to be the person who executed the foregoing instrument and acknowledge the same.
, aJ Notary Publi 'La Crosse
, Wisconsin My commission expires. February 21, 1988
)
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