ML20086N231
| ML20086N231 | |
| Person / Time | |
|---|---|
| Site: | 05200002 |
| Issue date: | 05/31/1988 |
| From: | ABB COMBUSTION ENGINEERING NUCLEAR FUEL (FORMERLY |
| To: | |
| Shared Package | |
| ML19351A936 | List: |
| References | |
| CEN-304-NP, CEN-304-NP-R02-NP, CEN-304-NP-R2-NP, NUDOCS 9112190178 | |
| Download: ML20086N231 (80) | |
Text
{{#Wiki_filter:FUNCTIONAL DESIGN REQUIREMENTS FOR A CONTROL ELEMENT ASSEMBLY CALCULATOR CEN-304-NP REVISION 02-NP Nuclear Power Systems. COMBUSTION ENGINEERING, INC. Windsor, Connecticut May, 1988 (,, a 9112190178 911209 E FDR ADOCK OT'20) ~
LEGAL NOTICE This report was prepared as an account of work sponsored by Combustion Engineering, Inc. Neither Combustion Engineering, nor any person acting on its behalf:
- a. Makes any warranty or representation, express or implied including the warranties of fitness for a particular purpose or merchantability, with respect to the accuracy, completeness, or usefulness of the information contained in this report, or that the use of any information, apparatus, method, or process disclosed in this report may not infringe privately owned rights; or g
- b. Assumes any liabilities with respect to the use of, or for damages resulting from the use of, any information, apparatus, method or process disclosed in this report, t
O CEAC Func. Design Requirements CEN-304 Revision 00 Page II
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ABSTRACT This document provides a description of the CEA Calculator (CEAC) and CEA Penalty Factor Algorith functional design to be implemented in the Core-Protection Calculator (CPC) System of the Reactor Protection , System. The scope of this functional description includes detailed specification of the CEAC Penalty Factor Algorithm, which is a component of the CPC/CEAC software, ,
- Two CEACs are provided in the Core Protection Calculator System. Each CEAC receives all of the CEA positions and calculates two per,alty factors based on-the severity.of CEA deviation within a subgroup. These two penalty-factors are transmitted to the CPCs to be included in the DNBR and LPD calculations. Detailed algorithm descriptions are provided.-
The algorithm equations are written in symbolic algebra. All variables
-are defined, and units are specified where applicable. In addition, the' 16-bit output buffer,-which transmits' the penalty factors to the
- CPCs, is defined.
.Rcvision 01-NP incorporates all.the changes described (and approved).
in-Reference 1.4.10.
-Revision 02-NP incorporates editorial changes' including those for plants with part-strength CEAs which are, for example, used by Ycnggwang3and4'(YGN3and4). Changes will be marked by revision ,
. lines.in the right hand margin.
y 4 CEN-304-NP Revision 02-NP Page ill
TABL E OF CONTENTS, ) Section No. Title Pace No. ABSTRACT III TABLE OF CONTENTS IV LIST OF FIGURES, TABLES AND APPENDICES VI LIST OF ACRONYMS AND DEFINITIONS VII
1.0 INTRODUCTION
1-1 1.1 PURPOSE 11 1.2 SCOPE I.1 1.3 APPL ICABIL ITY 12 1.4 REQUIRED REFERENCES 1-2 2.0 CEAC DESIGN BASIS 21 2.1 SPECIFIED-FUEL DESIGN LIMITS 2-1 2.2 ANTICIPATED OPERATIONAL OCCURRENCES (A00's) 2-1 3.0 FUNCTIONAL DESIGN AND COMPUTER DESIGN REOUIREMENTS 3-1 3.1 CEA CALCUL ATOR PENALTY FACTOR ALGORITHM FUNCTIONAL REQUIREMENT 31 3.1.1 Requiremen,ts for Accommodation of Defined Single CEA-Related A00's 3-1 3.1.2 Inputs and Outputs 3-2 3.2 PROGRAM STRUCTURE 3-4 3.3 PROGRAM TIMING AND INPUT SAMPLING RATES 3-6 3.4 PROGRAM INTERFACES 3-7 3.4.1 CEAC Failure Fla9 3-9 3.4.2 Case 2 Deviation Fla9 3-10 3.4.3 Reactor Power Cutback Fla9 3-10 3.4.4 Scaling Fla9 3-11 3.4.5 CEAC Off-L ine Storage and Reloading 3-11
'O CEAC Functional Design Requirements CEN-304 Revision 01 Page IV
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4 % ;w P LIST OF ACRONYMS AND DEFINITIONS
-Name- Def %ition ANO ARKANSAS NUCLEAR ONE - UNIT 2 A00 ANTICIPATED OPERATIONAL OCCURRENCE CEA- -CONTROL-ELEMENT ASSEMBLY CEAC CONTROL ELEMENT ASSEMBL'Y CALCULATOR CEDM -CONTROL-ELEMENT DRIVE MECHANISM CPC CORE PROTECTION CALCULATOR CRT- CATHODE RAY TUBE DISPLAY UNIT
.DNBR DEPARTURE FROM NUCLEATE B0ILING RATIO LPD LOCAL POWER DENSITY
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PSR .PART STRENGTH R0D
'PLR PART LENGTH R0D MAX (---) . MAXIMUM VALUE OF THE FOLLOWING MIN (---) MINIMUM VALUE 0F THE FOLLOWING PVNGS-1,2,3 .PALO VERDE _ NUCLEAR' GENERATING STATION - UNITS 1, 2, 3
-RPC REACTOR POWER CUTBACK RSPT. : REED SWITCH POSITION TRANSMITTER SAFDL' -SPECIFIED ACCEPTABLE FUEL DESIGN-LIMITS LSONGS-2,3 . SAN ON0FRE NUCLEAR GENERATING STATION - UNITS 2, 3 WSES-3 WATERFORD STEAM AND ELECTRIC STATION - UNIT 3-
'YGN-3,4 YONGGWANG - UNITS 3, 4 '
CEN-304-NP Reynion.02-NP Page VII
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4
,5 LIST OF TABLES O
Table No. Title Page No. 3-1 CEAC-0UTPUT SIGNALS 3-5 3-2 EXAMPLE OF FAILED SENSOR ARRAYS 3-15 3-3 ADDRESSABLE CONSTANTS 3-17 4-1 . ASSIGNMENT OF CEOMs TO SUBGROUPS 4 - 4-2 ASSIGNMENTS OF SUBGROUPS TO C6NTROL GROUPS 4-4
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LIST OF FIGURES Fioure No. , Title Paae No. 3-1= CEA CALCULATOR INPUT INTERFACE DIAGRAM 3-3
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4-l' PENALTY FACTOR COMPONENTS 4-31 LIST OF APPENDICES Appendix Title Page No. A- REVISED SECTIONS AND TABLES FOR USE A1 - A6 WITH SYSTEM 80 PLANTS CEAC-Functional Design Requirements CEN-304 Revision 01 Page VI
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- l TABLE OF CONTENTS (Cont'd.)
Section No, Title Page No. 3.5 OPERATOR INTERFACE 3-12 3.5.1 Alarms and Annunciators 3-12 3.5.2 Displays and Indicators 3-12 3.5.3 Operator Inout 3-16 3.6 . INITIALIZATION 3-16 3.7 TESTING REQUIREMENTS 3-18
.4.0 ALGORITHM DESCRIPTION 4-1 4.1 PENALTY FACTOR ALGORITHM 4-2 4.1.1 Alcorithm Input 4-2 4.1.1.1- Determination of Reactor Power Cutback (RPC) 4-8 4.1.2 Determination of Deviation 4-14 4.1.3 Determination of Penalty Factors 4-25 4.1.4 Packing of Penalty Factors for Transmittal to CPCs
<-] 4-35 NJ 4.1.5 CEAC Initialization 4-38 4.1.6 CEAC Constants 4-40 l O
CEAC Functional Design Requirements CEN-304 Revision 01 Page V
k,- - d .. 1.0' INTRODUCTION lil- PURPOSE The purpose of this document is to provide a description of the latest approved Control Element Assembly Calculator (CEAC) and CEA Penalty. Factor _ Algorithm functional. design. This document incorporates all the approve,d modifications made to CEN-147-(S)
-(Reference 1.4.1) as documented in References 1.4.2 thru.1.4.4 and '
as. approved _in References 1.4.5 thru 1.4.9. Revision 01 incorporates all the changes' described (and approved) in Reference 1.4.10. Revision 01-NP is for NRC information only as it contains
'information-that has already been_ reviewed and approved by the NRC Staff. .This- document williserve as the base reference for future -
modif_ications and is intended _ to be updated as future modifications-
-are approved and implemented.
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. Revision 02-NP incorporates editorial changes including those necessary to make this document applicable to plants with
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-part-strength'CEAs. No modification to'the CEAC algor _ithms is involved in-this revision.
1.2: -SCOPE This4 Functional (Design Requirements document provides the following:
- 1. A description of the CEA Penalty Factor ' Algorithm to be '
implemented in the Core Protection Calculator System of the Reactor Protection Calculator System of the Reactor Protection System, '
- 2. -A description of the algorithms to initiate alarms for CEA sensor failure and'CEA deviation,
- 3. A description of a diagnostic failed sensor data stack, L 4. The requirements on CEAC/CPC interfaces, system interfaces, and system initialization.
CEN-304-NP Revision 02-NP Page 1 .
The Functional Design Requirements described in this document when implemented with appropriate data base and addressable constants meet the design bases for CEAC given in Section 2.0. Where significant differences exist between System 80 and pre-system 80 plants (e.g. alarms, annunciators, displays, indicator and the assignment of CEAC's and subgroups), the document provides the pre-system 80 information with corresponding system 80 information contained in Appendix A. 1.3 APPLICABILITY This document is a generic description of the CEAC Functional Design Requirements. It is currently applicable to SONGS 2 and 3 (Cycle 3 and later), ANO-2 (Cycle 5 and later), WSES-3 (Cycle 2 and later), PVNGS-1, 2 and 3 (Cycle 2 and later), and YGN 3 and 4 (all cycles), b V 1.4 REQUIRED REFERENCES 1.4.1 Functional Design Requirements for a Control Element Assembly Calculator,CEN-148-(S)-P, January,1981. 1.4.2 CPC/CEAC Software Modifications for Waterford 3. CEN-197(C)-P, March, 1982. 1.4.3 CPC/CEAC Software Modifications for System 80, LD-82-038, March 1982.
.4., CPC/CEAC Software Modification for San Onofre Nuclear Generating Station Units No. 2 and 3, CEN-281(S)-P, July 1984.
1.4.5 Safety Evaluation Report related to operation of San Onofre Nuclear Generating Station, Unit 2 and 3, Docket Nos. 50-361 and 50-362, (t Southern California Edison Company, January 1982, CEN-304-NP Revision 02-NP Page 1-2
Qw.)\ 1.4.6 Safety Evaluation Report Related to the Operation of Waterford Steam Ele.:tric Station Unit No. 3, Docket No. 50-382, Louisiana Power and Light Company, July 1981. 1.4.7 Safety Evaluation Report Related to the Operation of Palo Verde Nuclear Generating Station, Units 1, 2 and 3, Docket Nos. STN-50-528, STN 50-529, and STN 50-5'30, Arizona Public Service Company, October 1984. 1.4.8 Safety Evaluation Related to Amendment No. 32 to NPF-10 and Amendment No. 21 to NPF-15 for San Onofre Nuclear Generating Station, Units 2 and 3, Docket Nos. 50-361 and 50-362, Southern California Edison Company, March 1985. 1.4.9 Safety Evaluation Related to Amendment No. 66 of Facility Operating License No. NPF-6, Arkansas Power and Light Company, Arkansas Nuclear One Unit 2, Docket No. 50-368, May 1985. [)T "w. 1.4.10 CPC/CEAC Software Modifications for the CPC Improvement Program, CEN-308-P-A, April 1986. I h U t CEN-304-NP Revision 02-NP Page 1-3 f
^ h// 2.0- CEAC DESIGN BASIS The function of the CEAC is to scan all CEA positions and, based on any single-CEA deviation detected within a CEA subgroup, to calculate the single CEA position-related penalty factors necessary to ensure that the CPCs calculate conservative approximations _to
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the actual core peak Local Power Den'sity.(LPD)-and Departure from Nucleate Boiling Ratio (DNBRT during single CEA-related Anticipated Operational Occurrences (A00s) which require CPCS protection. The CEAC must also be capable of detecting a reactor. power cutback event. 2.1 SPECIFIED FUEL DESIGN LIMITS The fuel design limits used to define-the low DNBR and LPD trip settings in the CPC to-ensure the following Specified Acceptable Fuel Design Limits'(SAFDLs) are not exceeded are: a.- The DNBR in the limiting coolant channel in the core shall be maintained such that there is at least a 95% probability, with 95% confidence, that DNB-is avoided. - b.- The peak LPD in the _ limiting fuel pin _in the core shall be maintained such that ' centerline fuel melting-is avoided.- - 2.2 ANTICIPATED OPERATIONAL OCCURRENCES (A00s)
- Anticipated operational occurrences are-defined in Appendix A of 10CFR50 (General. Design Criteria for Nuclear Power Plants)_as:
...those conditions of normal operation which are expected to occur one or more times during -the life of the nuclear power unit..."
L CEN-304-NP Revision.02-NP Page 2-1
-{;_. (.-) The A00s accommodated by the CPCS using the CEAC-generated penalty factors are the insertion or withdrawal of a single CEA including: A. Uncontrolled insection or withdrawal of a single CEA; B. A single cropped CEA; C. A single CEA sticking, with the remainder of the CEAs in that subgroup moving; D. A statically misaligned CEA. e> h%.) CEN-304-NP Revision 02-NP Page 2-2
3.0 FUNCTIONAL DESIGN AND COMPUTER DESIGN RE0UIREMENTS (l> )s
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3.1 CEA cal.CUL ATOR PENALTY FACTOR ALGORITHM FUNCTIONAL REQUIREMENT CEA insertion or withdrawal is expected to occur according to the sequence prescribed in the plant Technical Specifications. The CPC/CEAC system, however, must account for the increased radial peaking factor that would result from CEA motion not in accordance with the prescribed sequence.' CPC determines radial peaking factors based on the prescribed sequence and corrects for misoperations involving subgroups and groups (out of sequence insertion, subgroup deviations from their group, and excessive insertion of PLCEAs). However, CPC cannot detect- deviations of single CEAs from their subgroup since any CPC will.only see one member of a subgroup. The CEA calculator (CEAC) provides adjustmer to radial peaking factors for those misoperations that are not detectable by the CPCs, g Specifically, the CEAC compares the positions of the four (or five) W CEAs in each subgroup to decide if a significant deviation is present. Should such a deviation be detected, the CEAC determines, and sends to the CPC, two penalty factor multipliers; one each for the DNBR and LPD calculations. The penalty factors accommodate changes in the core axial and radial power distributions that are not directly perceived by CPC and are selected to assure that CPC obtains conservative estimates of.the peak local power density and minimum DN8R for individual CEA-i lated A00s that require a CPCS trip. To satisfy these requirements, the following specific functional requirement, as a minimum; must be satisfied 3.1.i Recuirements for Accommodation of Defined Sinaie CEA-Related A00s The CEA deviation Penalty Factors generated by the CEAC fo ' use in ,, the CPC trip functior: must be desigied to accommodate the
) individual CEA-related A00s described in Section 2.7 The bases for this requirement are:
CEAC Functional Design Requirements CEN-304 dev sion 01-P d Page 3-1
1. 1
~ p*"A 1. Criteria 25 and 29 of 10CFR50 Appendix A, " General Design Criteria for Nuclear Power Plants."
- 2. Regulatory Guide 1.70.
1 3.1.2 Inputs and Outputs The CEACs shall each receive analog core axial CEA position measurement signals which originate from one of two Reed Switch Position Transmitters (RSPTs) associated with each CEA. Each CEA position is measured by two redundant independent RSPTS which
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transmit analog signals to two redundant independent CEACs (refer to Figure 3-1 for ANO-2) -The resolution requirements on the CEAC measurement of CEA position shall be such that (excluding process signal error) CEA_ position shall be determined to within 0.5%. The RSPT consists of a series of magnetically actuated reed switches fN spaced at intervals along-the RSPT assembly and wired with precision resistors in a voltage divider network. The RSPT is affixed adjacent to the Control Element Drive Mechanism (CEDM) pressure housing and CEA extension shaft. A magnet attached to the CEA extension shaft actuates the. adjacent reed switches, causing a voltage signal proportional to the CEA-position to be transmitted for each CEA. The two RSPTs are isolated both electrically and physically from each other. The CEAC input signal derived from the
-RSPT output has a range of 5 to 10 volts corresponding to O to_150
' inches of CEA travel, or Oi, to 100% withdrawal.
The CEAC shall calculate the CEA deviation Penalcy Factors based on 4 CEA position sensor input-data obtained from each of the RSPTs (refer to Figure 3-1 for typical 81 CEA Plant). The components of the CEA deviation-Penalty Factors are determined from the following data:
- 1. Two static penalty factor components calculated as functions of
. V- deviation magnitude within a subgroup; one each for DNBR and (- LPD. CEAC Functional Design Requirements CEN-304 Revision 01 Page 3-2 1- ---_-_ _ _ _
FIGURE 3-1 TYPICAL CEA LALCULATOR INPUT INTERFACE DIAGRAM (Foran81CEAPlant) N
'(
CEN-304-NP Revision 02-NP Page 3-3
(1 '
- 2. A dynamic xenon penalty factor component calculated as a
(/ function of elapsed time during which excess deviation exists in the subgroup.
- 3. Two correction constants for the Xenon component; one each for DNBR and LPD.
The output signals for each CEAC are listed in Table 3-1. The two contact outputs must actuate operator alarms. The six digital-word outputs form the 16-bit output buffer which transmits the CEA penalty factors to the CPCs. The CEAC Failure Flag indicates that (1) the quantity of deviating CEAs per core quadrant or (2) the quantity of failed sensors exceeds limiting pre-set numbers. Actuation of the CEA Failure Flag is described in more detail in Section 3.4.1. The Scale Flag indicates the range of the penalty factors, and is described in more detail in Section 3.4.3. 3.2 PROGRAM STRUCTURE TheCEACdesignbasesrequireIhatthecalculatorbecapableof detecting a reactor power cutback event, detecting CEA deviation, calculating the single CEA deviation penalty factors, and indicating by alarm and indicator flag CEA deviation, CEAC failure, and sensor out-of-range failures. In addition, the CEAC will provide diagnostic information on CEA sensor failures. Therefore, the CEAC Penalty Factor Algorithm has been designed:
- 1. To recognize the initiation of a reactor power cutback event.
- 2. To calculate the deviation (difference in position) amongst the CEAs in each subgroup.
- 3. To recognize excessive CEA deviation within a subgroup, and to identify each occurrence as a single CEA withdrawal, single CEA
, ,,s v insertion, or multiple CEA deviations within a subgroup and (,) communicate this recognition to the CPCs. CEAC Functional Design Requirements CEN-304 Revision 01 Page 3 4
Table 3-1 CEAC Output Signals [G)- Signal Type Range CEAC Failure Flag Digital Word I Packed DNBR Penalty Factor Digital Word 1 (minus 1.0) , Multiple CEA Deviations Digital Word 1 in-Subgroup Flag Reactor-Power Cutback Flag Digital Word 1 Packed LPD Penalty Factor- Digital Word I (minus-1.0) , Digital Word I
, ('s ~ Scale Flag V
Sensor out-of-range , Contact Output - Alarm CEA Deviation Alarm Contact Output
- 1. -Part of 16-bit output buffer.
- 2. See Section 3.4 4
L( ' CEAC Func. Design Requirements CEN-304 Revision 00 Page 3-5
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l l L i f_V 4 To calculate and/or look up a penalty factor.for LPD, and a penalty factor for DNBR based on the type of deviation event, the magnitude of the deviation, the CEA subgroup with the deviation, the CEA configuration, and the elapsed time since the start of the deviation. The LPD and DNBR penalty factors shall be selected as the maximum of the LPD and DNBR penalty factors calculated for each subgroup. The maximum penalty factors minus one will be transmitted to the CPCs as part of the output of the CEAC. *
- 5. To determine the status of the CEAC sensor fail alarm and the CEA deviation alarm._
- 6. To check some conditions under which CEAC (or upstream hardware) failure should be indicated to the CPCs.
7 To provide diagnostic information on CEA sensor failures, and [N on the causes of a CEAC penalty factor. v) s
- 8. To provide an indicator to _the CPCs of the scale used in determining the penalty factors transmitted.
- 9. To support CEA CRT display software by calculating parameters used for the display.
3.3 PROGRAM TIMING AND INPUT SAMPLING RATES (See Appendix A for System 80 Plants) The CEAC Penalty. Factor Algorithm sof tware is designed for the purpose of providing, for existing CEA configurations, an on-line real-time determination of the single CEA deviation DNBR and LPD penalty factors to be apolied in the CPC determination of the hot pin heat flux distribution, the adjusted compensated core average power, and the local power density. The algorithm required for this (.g kj purpose is time oriented, with a calculation scheduling rate and updats period that is compatible with overall CEAC/CPC system
-CEAC Functional Design Requirements CEN-304 Revision 01 Page 3-6
response requirements. The execution period is the maximum time in seconds from the time CEA RSPT sensors are scanned to the time the CEAC calculated outputs are updated with new information from that input scan and calculatien. The calculations shall be scheduled in such a manner that the update requirements are met. There are two CEAC System update periods:
- 1. The Update Period This update period consists of a periodic fixed c algorithm scheduling rate. The CEAC Penalty Factor
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Program outputs shall be updated every
- 2. The Uptste' Period O This update consists of a fixed algorithm scheduling rate with
. The CEAC Penalty Factor Program calculated output to a CRT bar graph display showing individual CEA positions arranged in subgroups and groups shall be updated at least every ,
The tolerance on the execution periods is . 3.4 PROGRAM INTERFACES Communications with the CPCs must be rapid and simple. In addition, the output to the CPCs must not change until after execution of the CEACs has been completed. This is accomplished by a 16-bit output buffer which transmits data to each CPC. This output buffer shall have a memory location, and the 16 bits shall be assigned in the following manner: (O CEAC Functional Design Requirements CEN-304 Revision 01 Page 3-7
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CEAC Functional Design Requirements CEN-304 Revision 01 Page 3-8
1 f K ,) CEAC Failure Flag
' A 'CEAC: failure flag _shall be transmitted to the CPCs as part of the 16-bit output buffer. - This flag shall be set true when either or both of the following conditions occur:
- The CEAC Penalty Factor Program shall perfos sensor out-of-range .
. validity checks en the-raw RSPTcsensor input-data and initiate a sensor-out-of-range alarm when out 'o? range conditions are detected.
- Analog signals outside the acceptable operatingfrange represent failure of the RSPT. cif this-check indicates sensor in-range. a
, is then performed.. If either of these
-. checks fail,.the sensor fail flag is set.
In addition,- the CEAC failure flag shall' set-for internal' processor faults including fixed point divide faults. floating point arithmetic fault, memory parity errors, illegal machine instruction, . or failure to meet the' timing requirements of Section 3.3.
-: !O-
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CEAC Functional Design Requirements CEN-304 Revision 01 Page 3-9
l f 3.4.2 Case 2 Deviation Flag A Case 2 deviation (or large penalty factor) flag shall be trans-mitted to the CPCs as part of the 16-bit output buffer. This flag shall be set true when either or both of the following conditions occur: The CEAC Penalty Factor Program shall check for indications of i 3.4.3 Reactor Power Cutback Flag A Reactot Pt-e." Cutback (RPC) Flag shall be transmitted to the CPCs as part of the 16-bit output buffer. This flag shall be set (IRPC=1) when the following conditions occur: D l CEN-304-NP Revision 02-NP Page 3-10
60 3.4.4 Scaling Flag - After the DNBR and LPD penalty factors havi been calculated, each penalty factor is prepared for packing intt the 16-bit output buffer (D 3.4.5 CEAC Off-line Storage and Reloading To accommodate events where reloading of the CEAC Penalty Factor Algorithm program is required because of software and/or hardware f:il,res, a means shall be provided to permit rapid reloading of the CCAC software from a suitable off-line mass storage device C CEAC Functional Design Requirements CEN-304 Revision 01 Page 3-11
(one per CEAC). The off-line storag: device shall be utilized {) for normal CEAC start-up loading but not during normal CEAC operation, 3.5 OPERATOR INTERFACE (See Appendix A for System 80 Plants) The reactor operator shall be informed of the status of the CEACs by three mechanisms.
- 1. The calculators generate alarms to alert the operator to CEA _
sensor failure or excessive CEA deviation.
- 2. The CRT Video Monitor displays the position of the individual -
CEAs arranged into subgroups and coctrol groups utilizing a bar graph representation, the floating point values of the two penalty factors, and a flag to indicate the cause of any alarms.
- 3. The CPC/CEAC operator's module displays CEAC inputs, selected intermediate variables, and outputs.
3.5.1 Alarms and Annunciators A CEA deviation alarm (including Case 2 type deviations) and a failed sensor alarm shall be provided to the Plant Annunciator System (autible and visual) and to the CPC/CEAC operator's module. Removal of the alarm indication should be prohibited unless the condition causing the alarm no longer exists. 3.5.2 Disolays and Indicators Both CEACs shall be linked to a single CRT Display Generator for the purposes cf displaying individual CEA position information. The connection between the data link and each individual CEAC shall be f made via an appropriate isolation device (as defined in IEEE Std. N ) j CEAC Functional Design Requirements CEN-304 Revision 01 Page 3-12
279-1971). A manual selection switch shall be utilized to detertnine J which of the two CEACs the Display Generator will utilize in generating a CEA position display. The CEA Position Display (Figure 3-1) consists of a CRT Video Monitor and a n', play Generator, g The CRT Video Monitor shall display the position of the individual CEAs arranged into subgroups by control groups utilizing a bar graph representation. The CEAs and subgroups assigned to each control group shall be recorded above the bar graphs. The CRT shall provide an indication of CEA deviation which allows the deviating CEAs to be identified as well as the magnitude of the deviation. Provisions shall also be made to allow the operator to obtain a digital position read out in units of inches from the bottom of the core by addressing the particular point I.D. of the CEA on the operator's module. Certain CEAC intermediate variables and outputs (including the LPD and DNBR penalty factors and the packed penalty factor word to be transmitted to the CPCs) shall be available through the operator's module. Each CEAC shall provide diagnostic information to the operator via the operator's module or a teletype. The three types of diagnostic information to be provided are:
- 1. Failed sensor stack.
- 2. A " snapshot" or listing of CEA positions, penalty factors, and time of occurrence of the deviation.
- 3. ?. flag indicating the cause of any alarm.
Each CEAC performs sensor input out-of-range checks b; J CEAC Functional Design Requirements CEN-304 Revision 01 Page 3-13
)
. This information can be retrieved through the operator's Ndule or a teletype. The failed sensor stack should be saved through auto-restarts.
A " snapshot" of CEA positions, penalty factors, and time of deviation cccurrence is initiated by 1) a CEAC penalty factor greater than one, 2) the large PF flag, 3) a CFAC failure This information caa be retrieved through a telctype. The CEAC snapshot should be saved through auto-restarts., Al ~ fail indication is transmittoa to the CPCs under the following conditions: (. CEAC Functional Design Requirements CEN-304 Revision 01 Page 3-14
. _ . _ -._. _ _ _ . . _ . _ . . ~ _ _ . . . _ _ _ _ . - _ _ _ _._..__ _ _ _ .
T bla_ _ 1_e_ -2 Example of Failed Sensor Arran 7 I i [
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i CEAC Func Design Requirements CEN-304 Revision 00 Page 3-15 L' . , - - - . . - - - . . . , , . - . . - - .
, - . , - , . , - - - , . , , , . . . . ~ , - , , , . - - . . . . - - . , . , . . . , , . . . - - . . , , , , , - - - , -
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- 3. Initialization and in-test mode, 4 CEAC hardware si;r> ,
- 5. CEAC memory unprotected.
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- 6. Watchdog timer timeout.
3.5.3 Operator Input The operator must have the capability to change a limited set of program constants, called addressable constants, via the input / output device. Modification of addressable constants shall be permitted only when a manual interlock has been activated. In
' addition mea;.s shall be provided to prevent modification of any constants not designated " addressable". The required addressatile constants are limited to ,one,, constant for clearing the snapshot buffer (3.5.2), one constant for the Reactor Power Cutback maximum time limit and one constant for rewriting the entire CRT display on command. The required addressable constants are listed in Table 3-3.
3.6 INITI AL IZATION The CEACs must be cap,able of initializing to steady state operation for any allowable plant operating condition. Initialization should be complete within of initial CEAC startup or of restart following a CEAC failure or in-test condition. Until initialization of a CEAC is complete, the CEAC f ailure flag shall b' > t O CEAC Functional Design Requirements CEN-304 Revision 01 Page 3-16
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'x _ ' Table 3-3 Addressable Constants Synbol Definition Range BUTTRP Snapshot Buffer Control Flag TCBP Maximum time that the RPC flag Can Remain Set (Seconds)
TCOUNT II) CRT Display Rewrite Control Flag (1) TCOUNT is not necessary for SYSTEM 80 designs. (t,qj
'qJ CEN-304-NP Revision 02-NP Page 3-17
f , During initialization. the calculated penalty factors shall approach the steady state value from the conservative direction. jnijialization shall be considered to be complete after at least
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executions of the CEAC initialization program have occurred. 3.7 TESTING REQUIREMENTS The CEAC shall be designed to perform periodic testing of the CEAC Penelty Factor Program upon oper4 tor cemand. The bases for this reautrement are:
- 1. IEEE Std. 338-1971, "!EEE Trial Use Criteria for the Periodic Testing of Nuclear Power Generating Station Protection Systems."
- 2. Criteria 21 and ?? of 10CFR50 Appendix A, " General Design r Criteria for Nuclear Power Plants."
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- 3. Regulatory Guide 1.22, " Periodic Testing o'f Protection System Actuation functions."
The testing of the system shall be accomplished by disabling the input interface and simulating new inputs from a periodic testing data base. Selected outputs will then be checked against a corresponding expected value data base, and differences will be identified. During the time.the-CEAC is performing the periodic test a digitel- code s, hall be generated hnd transmitted to the - CPCs to identify that the CEAC unit is in-test.- I 1 CEAC Functional-Design Requirements CEN-304 Revision 01 Page 3-18
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4.0 ALGDRITHM DESCRIPTION This section includes a detailed description of the functions to be performed by the CEAC Program. For the program described below. the : sequence of computations reouired is described in sufficient detail to allow the software designer to specify the coding of the ! protection program. The penalty factor algorithm produces two penalty factors, one for DNBR and one for LPD. These penalty factors are found by taking the largest DNBR penalty factor and the largest LPD penalty factor calculated for any subgroup. The penalty factors on the subgroup , level are formed by combining a static DNBR penalty factor component with a dynamic Xenon penalty f6ctor component, and by combining a static LPD penalty factor component with a dynamic Xenon penalty factor component. (^
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4.1 PENALTY FACTOR ALGORITHM 4.1.1 Algorithm In_pu_t The inputs to the algorithm are a set of live CEA position signals received from the reed switch position transmitters. Each signal is processed to screen out false signals, i.e. each signal is checked for out-of-range and _
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TAME 4-1 Typical Assignment of CEDMs to Subgroups (For an 81 CEA Plent) Sub-GroupNo.(2) CEDM No. 1 2,3,4,5 2 6,7,8,9 3 10, 11, 12, 13 4 14, 16, 18, 20 5 15, 17, 19, 21 6 22, 23, 24, 25 7 26, 27, 28, 29 8 30, 32, 34, 36 9 31, 33, 35, 37 10 38, 40, 42, 44 11 39, 41, 43, 45 12 46, 47, 48, 49 13 50, 52, 54, 56 14 51, 53, 55, 57 15 58, 59, 60, 61 16 62, 64, 66, 68 17 63, 65, 67, 69 18 70, 73, 76, 79 19 71, 74, 77, 80 20 72, 75, 78, 81 xx(1) 1
- 1. CEDM No. 1 is to be capable of being assigned to any one of the 20 subgroups.
- 2. The assignment of CEDMs to subgroups as controlled by the CEDMCS is fixed for the life of the plant (except for CEDM #1) 1 O
CEN-304-NP Revision 02-NP page 4-3
I ( TABLE 4-2 () Typical Assignments of Subgroups to Control Groups I2} ASSIGNMENT OF SUBGROUPS TO CONTROL GROUPS CONTR01. GROUPS II) * (Subgrnup No.) Regulating Group #6 12 Regulating Group #b 15 Regulating Group #4 3 Regulating Group #3 16, 17 Regulating Group #2 2, 19 Regulating Group #1 10, 11 Shutdown Group A 13, 14, 18, 20 gr-) Shutdown Group B 1, 4, 5, 8, 9
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P1 6 P2 7 Notes: -
- 1. The highest numbered Regulating Control Group is the first to be inserted in sequence and Group #1 is the last. Similarly, Regulating Control Group #1 is the first to be withdrawn in sequence and highest numbered Group is the last.
- 2. This subgroup assignment will vary according to plant. Table 4-2 presents typical subgroup assignments for a CEA group structure similar to ANO-2,
- 3. Also applies to part-strength CEA groups.
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h APPENDIX A PEVISED SECTIONS FOR USE WITH SYSTEM 80 PL ANTS Appendix A contains those sections which would be changed for application to System 80 plants. Appendix A section numbers correspond to the main document numbers, but are preceded with an "A". For application to System 80, the appendix sections supercede those with corresponding numbers in the main document. Sections which have generic ' applicability, therefore, are not contained in this appendix. The following is a list of Appendix A section numbers with their corresponding titles and page numbers. Section No. Ti tle Page No. A3.3 Program Timing and Input Sampling Rates A2
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y A3.3 PROGRAM TIMING AND INPUT SAMPLING RATES I (' x j The CEAC Penalty Factor Algorithm sof twere is designed for the purpose of providing, for existing CEA configurations, an on-line real-time determination of the single CEA deviation related DNBR and LPD penalty factors to be applied in the CPC determination of the hot pin heat flux distribution, the adjusted compensated core average power, and the local power density. The algorithm required for thi. purpose is time oriented, with a calculation scheduling rate and updata period that is compatible with overall CEAC/CPC system response requirements. The execution period is the maximum time in seconds from the time CEA RSPT sensors are scanned to the time the CEAC calculated outputs are updated with new information from that input scan and calculation. The calculations shall be scheduled in such a manner that the update requirements are met. There are two CEAC System update periods:
/mS 1. The Update Period 9 _ _
This update period consists of a periodic fixed algorithm scheduling rate. The CEAC Penalty Factor Program outputs shall be updated every .
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- 2. I The g Update Period This update consists of a fixed algorithm scheduling rate with
! . The CEAC Penalty 7actorProgramc'alculatedoutputtoaCRTbargraphdisplay showing individual CEA positions arranged in sub goups and groups shall be updated at least every .
The tolerance on the execution periods is th Y CEAC Functional Design Requirements CEN-304 Revision 01 Page A2
n (one per CEAC). The off-line storage device shall be utilized for S ,) normal CEAC start-up loading but not during normal CEAC operation. A3,5 OPERATOR INTERFACE The reactor operator shall be informed of the status of the CEACs by three mechanisms:
- 1. The calculators generate
- alarms to alert the operator to CEA sensor failure or excessive CEA deviation.
- 2. The CRT Video Monitor displays the position of the individual CEAS arranged into subgroups and control groups utilizing a bar graph rspresentation. If a CEA deviation exists, the group and subgroup having the deviation, the CEAs assigned to the subgroup with the deviation, and the position for each of these rCAs in inches from the bottom of the core will be displayed below the bar graph representation. This display of CEA deviation information is ordered by decreasing penalty factor magnitude and is limited to the information associated with three CEA deviations. In addition CEA sensor failure information (CEA number and type of failure) shall be dis-played, if not preempted by CEA deviation information.
- 3. The CPC/CEAC operator's module provides CEAC inputs, selected intermediate variables, and outputs.
A3.5.1 Alarms and Annuncirtors A CEA deviation alarm (including Case 2 type deviations) and a failed sensor alarm shall be provided to the Plant Annunciator System (audible anJ visual) and to the CPC/CEAC operator's module. Removal of the alarm indication should be prohibited unless the condition causing the alarm no longer exists.
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CEAC Functional Design Requirements CEN-304 Revision 01 Page A3
A3.5.2 . Displays and Indicators~ {O Both CEACs shall be linked to a single CRT Display Generator for the purposes of displaying individual CEA position information. The connection between the data link and each individual CEAC shall be made via an appropriate isolation device (as defined in IEEE Std. 279-1971). A manual selection switch shall be utilized to determine which of the two CEACs the Display Gdnerator will utilize in generating a CEA position dis
- play. The CEA Position Display (Figure 3-1) consists of a CRT Video Monitor and a Display Generator.
The CRT Video Monitor shall display the position of the irdividual CEAs arranged into subgroups by control groups utilizing a bar graph representation. If a CEA deviation exists, the CRT shall identify the CEA's assigned to the subgroup with the deviation and shall indicate the position of these CEA's in inches from the bottom of the core below the bar graph representation. The CRT shall also display failed sensor information. O Provisions shall also be ma_de to allow the operator to obtain a digital position read out in units of inches from the bottom of the core by addressing the particular point I.D. of the CEA on the operator's module. Certain CEAC intermediate variables and outputs (including the LPD and DNBR penalty factors and the packed penalty factor word to be transmitted to the CPCs) shall be available through the operator's module. Each CEAC shall provide diagnostic information to the operator via the operator's module or a teletype. The three types of diagnostic information to be provided are:
- 1. Failed sensor stack.
- 2. A " snapshot" or listing of CEA positions, penalty factors, and time of occurrence of the devia tion.
J CEAC Functional Design Requirements CEN-304 Revision 01 Page A4
- 3. A flag indicating the cause of any alarm.
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, _ This information can be retrieved through the operator's module or a teletype. The
[d3 failed sensor stack should be saved through auto-restarts, A " snapshot" of CEA positions, penalty ' factors, and time of deviation occurrence is initiated by 1) a CEAC penalty factor greater than one, 2) the large PF flag, 3) a CEAC failure CEAC Func. Design Requirements CEN-304 Revision 00 Page A5 r . +.nw.~~~. --
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( (I A CEAC fail indication is transmitted'to the CPCs under-the
'V f allowing conditions:
=1. More .than-a pre-set number of sensors are indicated failed,
- 2. More than:a pre-set number of subgroups _ contain excessive deviation (excessive deviations are counted by core quadrant),
- 3. Initialization and in-test mode, 4 CEAC hardware-failure,
-5. _CEAC' memory unprotected, 6.- Watchdog timer timeout.
M - A3;5.3 Operator Input , The operator must have the capability to change a limited set'of program constants, called addressable constants, via-the input /
. output-device. Modification of addressable constants shall be Lpermitted.only when a manual interlock has been activated. In addition means-shall be provided to-prevent modification of any-
- constants not designated _. "_ addressable"_. ~ The required-addressable Econstants are limited to one constant for clearing the snapshot buffer (A3.5.2)-and one constant for the Reactor-Power Cutback maximum time limit.
A_ method:shall also be provided to permit rewriting the entire ~CRT
-display'on command.
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