Reactor Core and ComponentsSung-Quun ZeeManagerCore Dseign and Analysis Technology Dept.Korea Atomic Energy Research InstituteCONTENTS1. INTRODUCTION

2. PEACTOR

3. CORE COMPONENTS

3.1 Fuel Assemblies and Core Loading Pattern

3.2 Control Rods

3.3 Burnable Poisons

3.4 Grids

3.5 Instrumentation

4. CORE DESIGN BASES

4.1 General

4.2 Excess Reactivity and Fuel Burnup

4.3 Core Design Lifetime and Fuel Replacement Program

4.4 Negative Reactivity Feedback

4.5 Reactivity Coefficients

4.6 Burnable Poison Requirements

4.7 Stability Criteria

4.8 Maximum Controlled Reactivity Insertion Rate

4.9 Power Distribution Control

4.10 Excess CEA Worth with Stuck Rod Criteria

4.11 Chemical Shim Control

4.12 Maximum CEA Speeds

TABLETable 3-1Core Arrangement

Table 3-2Fuel Assemblies

Table 3-2Fuel Assemblies (cont'd)

Table 3-3Fuel Rods

Table 3-4Control Element Assembly

Table 3-5Burnable Absorber

Table 4.1Design Criteria

Table 4.3CORE PERFORMANCE CHARACTERISTICS

Table 4.5Comparison of Core Reactivity Coefficients

Table 4.10Comparison of Available CEA Worths and Allowances

FIGUREMaster Solution for NEACRP PWR Rod Ejection Benchmark Case C1

Comparison of Solutions for OECD MSLB Exercise II

View of SMART

SMART CORE LOADING PATTERN

CONTROL ELEMENT ASSIGNMENT

SHUTDOWN MARGIN AND REFUELING KEFF

CONTROL GROUP OPERATION

SMART BURNUP CHARACTERISTICS

MODERATOR TEMPERATURE COEFFICIENTS

Load Follow Operation

Load Follow Oreration Capability (14-2-6-2)(EOC)

Figure 2.1Reactor Vertical Arrangement

Figure 2.2Reactor Core Cross Section

Figure 2.3Isometric View of the Reactor Coolant System

Figure 2.4Reactor Flow Paths

Figure 3.1-aCore Loading Pattern

Figure 3.1-bFirst Cycle Assembly Fuel Loading Waterhole and Shim Placement

Figure 3.1-cFuel Assembly

Figure 3.1-dFuel Rod

Figure 3.2-aControl Element Assembly Locations

Figure 3.2-bFull-Strength Control Element Assembly (4-Element)

Figure 3.2-cFull-Strength Control Element Assembly(12-Element)

Figure 3.2-dPart-Strength Control Element Assembly

Figure 3.3-aPoison Rod

Figure 3.3-bCore-wise Burnable Poison Placement

Figure 3.3-cVaiation in K-inf of Assembly to the Change of Burnable Poison Co ntents

Figure 3.4Fuel Spacer Grid

Figure 3.5-aFixed In-core Instrument Assembly

Figure 3.5-bEx-core/In-core Detector Systems

Figure 4.4MTC vs. Moderator Temperature at BOC, HZP-HFP, Eq. Xe, ARO

Figure 4.5Fuel Temperature Coefficient

Figure 4.7PSCEA Controlled and Uncontrolled Oscillation

Figure 4.8Scram Worth vs. CEA Insertion

Figure 4.9Daily Load-Cycle Maneuvering Transient at BOC

1. INTRODUCTION

The design of a commercial light water reactor is such that the reactor core is loaded with a specified number of fuel assemblies that are generally identical in design but different in the amount of fissile material content. In the initial core the fuel assemblies differ in the initial enrichment of the fuel, and in subsequent fuel cycles they differ in the amount of the burnup of the fuel as well. The reactor is fueled at intervals varying from 12 to 24 moths. The refueling of a reactor consists of removing part of the core (a certain number of irradiated fuel assemblies, the number and identity of which are determined by a fuel management scheme) and loading an equal number of fresh and possibly previously burned fuel assemblies called the "reload batch". In general, after refueling, the neutronic, thermal-hydraulic, safety, and operating parameters of the core would be different from the previous fuel cycle. The design analyses required to determine the mechanical design, enrichment and number of assemblies of the initial or reload batches as well as the core loading pattern, the nuclear and thermal-hydraulic characteristics of the core, and the safety analyses demonstrating the safety of operation of the reactor is called core design. This section presents an overview of reactor core and components of Korean Standard Nuclear Power Plant (KSNP). In addition to this, a brief overview of the major elements of the core design process and the design criteria are provided.

2. REACTOR

The reactor is of the pressurized water type using two reactor coolant loops. A vertical cross section of the reactor is shown in Figure. 2.1. The reactor core is composed of 177 fuel assemblies and 73 control element assemblies (CEAs). The fuel assemblies are arranged to approximate a right circular cylinder with an equivalent diameter of 123 inches (3.12 meters) and an active length of 150 inches (3.81 meters). The fuel assembly, which provides for 236 fuel rod positions (16 16 array), consists of five guide tubes welded to spacer girds and is closed at the top and bottom by end fittings. The guide tubes each displace four fuel rod positions and provide channels with guide the CEAs over their entire length of travel. In-core instrumentation is installed in the central guide tube of selected fuel assemblies. The in-core instrumentation is routed into the bottom of the fuel assemblies, fuel rods, and CEA guide tubes.

The fuel is low-enrichment UO2in the form of ceramic pellets and is encapsulated in pre-pressurized Zircaloy tubes which from a hermetic enclosure.

The isometric view of the reactor coolant system is shown in Figure 2.3. The reactor coolant enters the inlet nozzles of the reactor vessel, flow downward between the reactor vessel wall and the core barrel, and passes through the flow skirt section, where the flow distribution is equalized, and into the lower plenum. The coolant then flows upward through the core removing heat from the fuel rods. The heated coolant enters the core outlet region where the coolant flows around the outside of control element assembly shroud tubes to the reactor vessel outlet nozzles. The schematic reactor flow paths is shown in Figure 2.4. The control element assembly shroud tubes protect the individual neutron absorber elements of the CEAs from the effect of coolant cross-flow above the core. The reactor internals support and orient the fuel assemblies, control element assemblies, and in-core instrumentation, and guide the reactor coolant through the reactor vessel. They also absorb static and dynamic loads and transmit the loads to the reactor vessel flange. They will safety perform their functions during normal operating, upset, and faulted conditions. The internals are designed to safety withstand forces due to dead weight, handling, temperature and pressure differentials, flow impingement, vibration, and seismic acceleration. All reactor components are considered Category I for seismic design. The design of the reactor internals limits deflection where required by function. The stress values of all structural members under normal operating and expected transient conditions are not greater than those established by Section of the ASME Code. The effect of neutron irradiation on the materials concerned is included in the design evaluation. The effect of accident loadings in the internals is included in the design analysis.

Reactivity control is provided by two independent system: the control element drive system and the chemical and volume control system. The control element drive system controls short-term reactivity changes and is used for long-term reactivity changes and can make the reactor subcritical without the benefit of the control element drive system. The design of the core and the reactor protection system prevents fuel damage limits from being exceeded for any single malfunction in either of the reactivity control systems. Details of the core components are discussed in the following section.

3. CORE COMPONENTS

The core components which affect the core design most are the fuel assemblies, the fuel pins, the Gd-bearing fuel rods (shims), the control rods, the materials used for the grids, guide tubes, and fuel rod cladding, and the in-core instrumentation.

3.1 Fuel Assemblies and Core Loading Pattern

The loading pattern for Cycle 1 of KNSP, showing fuel type in each core location, is displayed in Figure 3.1-a. The Cycle 1 design features a 4-batch, mixed central-zone loading. This loading pattern facilitates the transition of the initial core to the equilibrium cores as well as higher utilization of the initial-core fuel compared with conventional three batch patterns. The initial-core design also features a low-leakage type core loading pattern. This adaptation significantly reduces the overall neutron leakage relative to a four batch out-in scheme.

Many of the assemblies contain zones of lower enrichment fuel pins. This enrichment zoning technique is used to decrease the power peaking within an assembly and also to make intra-assembly power distribution insensitive to changes in the lattice pitch (via assembly or rod bowing). Due to the use of various enrichment zoning patterns and shim loadings, the fuel assemblies in the initial core are classified into nine different sub-batches as listed in Table and pictured in Figure 3.1-b, although only five different are shown in Figures 3.1-c and 3.1-d.

3.2 Control Rods

The control rods are inserted into either two or four of the available CEA guide tube locations. The center guide tube is left vacant in order to accommodate an in-core instrument assembly.

By combining 4 and 12 fingered CEAs, nearly all fuel assemblies in the core can be rodded with 73 Control Element Drive Mechanisms (CEDMs) as shown in Figure 3.2-a.

The CEA programming scheme defines five regulating banks, two shutdown banks, and one part-strength bank. The regulating and shutdown bank CEA fingers contain pellets made of B4C. Schematic drawings of 4 fingered and 12 fingered full length CEAs are shown in Figures 3.2-b and 3.2-c. The part strength rod (PSR), whose fingers contain inconel pellets, are used to assist in maneuvering and for controlling the axial power distribution. Figure 3.2-d shows the part strength control element assembly.

For the shutdown banks and some control banks, the normal position is fully withdrawn. Over extended periods of operation with these CEAs at one position, flow included vibrations of the CEA fingers can cause wear on the inside of the guide tubes. Therefore these CEAs are periodically within a small range of withdrawn positions. This allows the fully withdrawn CEAs to be moved among seven different positions (steps) on a rotating basis, usually once a month, thus preventing excessive guide tube wear at any location.

3.3 Burnable Poisons

Since the core is to be operated essentially with the unrodded state while at power, some provision must be made to offset or "hole down" the excess fuel reactivity present in the core for depletion requirements. If this hold-down were supplied only by soluble boron, the MTC would be positive over a significant portion of the cycle. To avoid this situation, lumped burnable poisons (shims) are used for the reactivity hold-down. In addition to MTC control, the lumped burnable poison plays an important role in controlling the radial power distribution by suppressing reactivity of the high enrichment assemblies. In the KNSP reactor, the shim is comprised in the top and bottom 5% of the shim rods. The axial power is small due to the axial leakage of neutrons.

Selected assemblies contain up to Gd shim rods placed in strategic locations within the assembly lattice of enriched fuel rods. Gadolinia is used as a burnable poison in the initial core design to reduce soluble boron requirements and to provide power distribution control while reducing the thermal margin degradation associated with fuel displacing burnable poisons (e.g., B4C/Al2O3shims). This integral burnable poison also offers the advantage of the strong initial reactivity hold-down characteristic of gadolinium in combination with a low residual poison worth at end-of-cycle. This design uses pellet concentration of 4 w/o gadolinia admixed in natural urania. Reactivity control is provided using relatively few (e.g., 4 or 8) gadolinia-bearing fuel rods per fuel assembly in the fuel assemblies requiring burnable poison. The use of natural UO2provides flexibility in the range of concentration of Gd2O3which determines the duration of the reactivity hold-down, while eliminating licensing concerns associated with fuel performance using gadolinia in enriched urania. Unlike the typical B4C burnable absorber rods, the gadolinia fuel rods (shims) have the same dimensional specifications as the normal fuel reds. Figure 3.3-b illustrates the arrangements of burnable poison within each poisoned assembly. Figure 3.3-c shows changes in assembly multiplication factor for varied poison contents in an assembly.

3.4 Grids

The fuel spacer grids maintain the fuel rod array by providing positive lateral restraint to the fuel rod but frictional restraint to axial fuel rod motion. The grids are fabricated from preformed zircaloy or inconel strips (the bottom spacer grid material is inconel) interlocked in an egg crate fashion and welded together. Each cell of the spacer grid contains two leaf springs and four arches. The leaf springs press the rod against the arches to restrict relative motion between the girds during a refueling operation. Zircaloy-4 is used for guide tubes and for girds located in the active fuel region of the fuel assembly because of its superior neutron economy properties. The ten Zircaloy-4 spacer grids are fastened to the Zircaloy-4 guide tubes by welding, and each grid is welded to each guide tube at eight location, four on the upper face of the grid and four on the lower face of the grid, where to the guide tubes due to material differences. It is supported by an Inconel 625 skirt which is welded to the spacer grid and to the perimeter of the lower end fitting. Figure 3.4 shows schematic of spaer grid.

3.5 Instrumentation

There are 45 in-core instrument (ICI) assemblies, each containing five self-powered detectors. The 45 instruments are strategically disributed about the reactor core, and the five detectors. The 45 instruments are strategically distributed about the reactor core, and the five detectors of each instrument assembly are axially distributed along the length of the core. The individual detectors are centered at 10, 30, 50 ,70 and 90% of the core height. This permits gross three dimensional power distribution mapping of the core from 10% to 125% of full power.

A complete in-core instrument assembly consists of five rhodium detectors, a background detector, a core exit thermocouple, and a calibration tube. The assembly is enclosed in a protective sheath, and terminated with a seal plug and an electrical connector. The individual ICI assemblies are positioned in the center guide tubes of the fuel assemblies at the 45 core locations. The core instrument pattern is optimized for the monitoring of azimuthal power tilts.

The core exit thermocouple is a type K, grounded junction element with chromel and alumel lead wires in accordance with ASTM standards. The thermocouple extends to the end of the ICI assembly and measures the primary coolant flow outlet temperature.

Typical in-core instrumentation assembly schematic is shown in Figure 3.5-a.

There are also three different kinds of ex-core detectors whose ranges overlap a minimum of two decades to assure that the neutron flux is continuously monitored from source level to 200% of full power. These detectors are used in three separate electronic "channels" as follow:Startup Channel (BF3proportional counters), Control Channel (dual-section uncompensated ionization chambers), and Safety Channel (three-section U235 fission chambers). Typical arrangement of In-core and Ex-core Detector system are shown Figure 3.5-b.

Summary description of the reactor core and core components are given Table 3-1 through 3-5.

4. CORE DESIGN BASES

4.1 General

In general, the specifications of the reactor core and components are determined in the core design process, especially in the nuclear design process. It is, thus, worth understanding what are the purpose of the core design. The major objectives of core design can be summarized as follows;1) Meet the energy production requirement (rated power x duration)2) Meet the design criteria to ensure safety of the core and fuel3) Maximize operational flexibility4) Minimize the power generation cost for economicsThe bases for the core design, especially nuclear design of the fuel and reactivity control system are very important to meet the above objectives. Therefore, the core design process starts from setting up of the proper design bases and requirements. In the following subsections, some design bases closely related to the fuel and reactivity control systems designs are discussed. The General Design Criteria mostly related with core design, as an example, are listed in Table 4.1 These criteria are similar to the criteria defined in the Korean Automic Law and Regulations.

4.2 Excess Reactivity and Fuel Burnup

The excess reactivity provided for each cycle is based on the depletion characteristics of the fuel and burnable poison and on the desired burnup for each cycle. The desired burnup is based on an economic analysis of the fuel cost and the projected operating load cycle for KNSP. The average burnup is chosen to ensure that the peak burnup is within the limits set by LOCA analysis. This design basis, along with the design basis in Subsection 4.8 satisfies General Design Criterion (GDC) 10. For KSNP, the peak pin burnup limit is recently increased and licensed from 52,000 MWD/MTU to 58,000 MWD/MTU to accommodate extended cycle operation of 18 months for subsequent cycles. The initial core average burnup amounts to 13,650 MWD/MTU.

4.3 Core Design Lifetime and Fuel Replacement Program

For early KSNP designs, the core design lifetime and fuel replacement program are based on approximately annual refueling with approximately one-fourth of the fuel assemblies replaced at each refueling in later cycles. The first cycle design lifetime is longer than later cycles to permit a more orderly transition to equilibrium cycle conditions. This four-batch core design concept has recently been changed to three-batch such that 18 months cycle operations can be achievable from the initial core to subsequent cycles, to further enhance plant lifetime economics.

Table 4.3 summarizes the core performance characteristics of KNSP.

4.4 Negative Reactivity Feedback

In the power operating range, the net effect of the prompt inherent nuclear feedback characteristics (fuel temperature coefficient, moderator temperature coefficient, and moderator pressure coefficient) tends to compensate for a rapid increase in reactivity. The negative reactivity feedback provided by the design as shown in Figure 4.4 satisfies General Design Criterion 11.

4.5 Reactivity Coefficients

The values of each coefficient of reactivity are consistent with the design basis for net reactivity feeback (Subsection 4.4), and analyses that predict acceptable consequences of postulated accidents and anticipated operational occurrences, where such analyses include the response of the reactor protection system (RPS). Table 4.5 and figure 4.5 show the reactivity coefficients of KNSP.

4.6 Burnable Poison Requirements

The burnable poison reactivity worth provided in the design is sufficient to ensure that the moderator coefficients of reactivity are consistent with the design bases in Subsection 4.5. For KSNP, burnable poison, namely Gd2O3with UO2is utilized. Gd2O3with UO2is so called integral burnable poison. Gd2O3has been extensively used for reload cores of Korean PWRs as burnable poison material. It's properties are well known and performance in the reactor core is well proven. Typical burnable poison loading in a fuel assembly is shown in Figure 3.1-b.

4.7 Stability Criteria

The reactor and the instrumentation and control systems are designed to detect and suppress xenon-induced power distributions that could, if not suppressed, result in conditions that exceed the specified acceptable fuel design limits (SAFDL). The design of the reactor and associated systems precludes the possibility of power level oscillations. This basis satisfies General Design Criterion 12. During the power ascension test period, the xenon oscillation control test is performed. Through this test, it is demonstrated that the reactor is properly controlled under the oscillatory xenon conditions. A typical xenon control by PSCEA for KSNP is shown in Figure 4.7

4.8 Maximum Controlled Reactivity Insertion Rate

The core, control element assemblies (CEAs), reactor regulating system, and boron charging portion of the chemical ans volume control system are designed so thea the potential amount and rate of reactivity insertion due to normal operation and postulated reactivity accidents do not result in the following:a. Violation of the specified acceptable fuel design limitsb. Damage to the reactor coolant pressure boundaryc. Disruption of the core or other reactor internals sufficient to impair the effectiveness of emergency core cooling systemTypical reactivity insertion rate curve for reactors similar to KSNP is shown in Figure 4.8. This design basis, along with Subsection 4.12, satisfies General Design Criteria 25 and 28.

4.9 Power Distribution Control

The core power distribution is controlled such that, in conjunction with other core operating parameters, the power distribution does not result in violation of the limiting conditions for operation. Limiting conditions for operation and limiting safety system settings are based on the accident analyses such that specified acceptable fuel design limits and other criteria are not exceeded for accidents. This basis, along with Subsection 4.2, satisfies General Design Criterion 10. A typical power shape due to reactor daily load swing is shown in Figure 4.9.

4.10 Excess CEA Worth with Stuck Rod Criteria

The amount of reactivity available from insertion of withdrawn CEAs under all power operating conditions, even when the highest worth CEA fails to insert, will provide for at least 1.4% excess CEA worth after cool-down to hot zero power, plus any additional shutdown reactivity requirements assumed in the safety analyses. This basis, along with Subsection 4.11, satisfies General Design Criteria 26 and 27. Table 4.10 compares the available CEA worths with allowances.

4.11 Chemical Shim Control

The chemical and volume control system (CVCS) is used to adjust the dissolved boron concentration in the moderator. After a reactor shutdown, this system is able to compensate for the reactivity changes associated with xenon decay and reactor coolant temperature decreases to ambient temperature, and it provides adequate shutdown margin during the refueling. This system also has the capability of controlling, independently of the CEAs, long-term reactivity changes due to fuel burnup and reactivity changes during xenon transients resulting from changes in reactor load. This design basis, along with Subsection 4.10, satisfies General Design Criteria 26 and 27.

4.12 Maximum CEA Speeds

Maximum CEA speeds are consistent with the maximum controlled reactivity insertion rate design basis in Subsection 4.8 The maximum CEA speed for safety analysis is 30 in/min.

Table 3-1 Core Arrangement

Number of Fuel Assemblies in Core, total 177

Number of CEAs 73

Number of Fuel Rod Locations41772

Number of Shim Rods 640

Spacing between Fuel Assemblies, Fuel Rod Surface to Surface, cm0.528

Hydraulic diameter, nominal channel, cm1.198

Total Flow Area (excluding guide tubes), m24.153

Core Equivalent Diameter, cm312.4

Core Circumscribed diameter, cm330.2

Total Fuel Loading, (all rod locations fuel rods), ton U76.34

Table 3-2 Fuel AssembliesAssemblyTypeNo.ofAssemblieswt%U-235No.of Fuel Rodsper AssemblyNo.of Gd Rodsper AssemblyGd2O3 wt%in Nat. UO2

A451.28236--

B202.34236--

B182.34/1.28176/5284

B2162.3423244

C122.84/2.34184/52--

C1322.84/2.34176/5284

D123.34/2.84184/52--

D183.34/2.84176/5284

D2243.34/2.84128/10084

Table 3-2 Fuel Assemblies (cont'd)Fuel Rod Array Square 16 16

Square Grid

TypeLeaf Spring

MaterialZircaloy-4

Number per Assembly 10

Bottom Spacer Grid

TypeLeaf Spring

MaterialInconel 625

Number per Assembly 1

Weight of Fuel Assembly, kg 654

Table 3-3 Fuel RodsFuel Rod Material (sintered pellet)UO2

Pellet Diameter, cm0.826

Pellet Length, cm0.991

Pellet Density, g/cm310.44

Clad MaterialZircaloy-4

Clad ID, cm0.843

Active Length, cm381

Plenum Length, cm24.5

Table 3-4 Control Element AssemblyFull LengthPart Length

Number658

Absorber Elements, No. per Assembly12 and 44

TypeCylindricalCylindrical

Clad Thickness, cmInconel 625Inconel 625

Clad O.D., cm2.0732.073

Control Element (CEA Fingers)

Poison Material (main/lower end)B4C/Felt metalInconel 625

and reduced dia. B4CSlug

Poison Length, cm344.17/31.75375.92

B4C Pellet

wt % Boron, minimum77.5N/A

Table 3-5 Burnable AbsorberAbsorber MaterialGd2O3-UO2

Pellet Diameter, cm0.826

Pellet Density (% theoretical)95.25

Theoretical density, UO2, g/cm310.96

Theoretical density, Gd2O3, g/cm37.41

Clad MaterialZircaloy-4

Clad ID, cm0.843

Active Length, cm342.9

Plenum Length, cm24.53

Table 4.1 Design Criteria10CFR50 APP.ACriterion NumberTitle

. Overall Requirements:

1Quality Standards and Records

2Design Bases for Protection Against Natural Phenomena

3Fire Protection

4Environmental and Dynamic Effects Design Bases

5Sharing of Structures, System, and Components

. Protection by Multiple Fission Product Barriers:

10Reactor Design

11Reactor Inherent Protection

12Suppression of Reactor Power Oscillations

13Instrumentation and Control

14Reactor Coolant Pressure Boundary

15Reactor Coolant System Design

16Containment Design

17Electric Power System

18Inspection and Testing of Electric Power System

19Control Room

. Protection and Reactivity Control Systems:

20Protection System Functions

21Protection System Reliability and Testability

22Protection System Independence

23Protection System Failure Modes

24Separation of Protection and Control Systems

25Protection System Requirements for Reactivity Control Malfunctions

26Reactor Control System Redundancy and Capability

27Combined Reactivity Control systems Capability

28Reactivity Limits

29Protection Against Anticipated Operational Occurrences

Table 4.3 CORE PERFORMANCE CHARACTERISTICS

Total Heat Output, MW(t) 2815

Heat Generated in Fuel, % 97.5

Reactor Coolant Temperature, C

Hot Zero Power 296

Hot Full Power 296

Design Core Average, Hot Full Power 312

Nominal Primary System Pressure, kg/cm2 158

Average Liner Heat Rate, kW/ft (W/cm)5.391 (176.9)

Specific Power, kW/kgU 36.88

Volumetric Power Density, kW/liter of core 96.26

1stCycle Length, EFPD 370

Core Average Burnup, MWD/MTU 13650

Batch Average Burnup, MWD/MTU ~43500

Peak Pin Burnup, MWD/MTU 1% Large negative MTC Core thermal margin > 15% Peaking factor, Fq < 2.8 RPV neutron fluence < 1.0 1020n.cm2/sec

SMART CORE LOADING PATTERNTypeTotalNumberof FA'sNumberof NormalFuelRodsNumberof GdpoisionRodNumberof Al2O3-B4Cshims

A82241228

B28240420

C2123648/16

Total5713,4682921,288

Figure 2.1 Reactor Vertical Arrangement

Figure 2.2 Reactor Core Cross Section

Figure 2.3 Isometric View of the Reactor Coolant System

Figure 2.4 Reactor Flow Paths

Figure 3.1-a Core Loading Pattern

Figure 3.1-b First Cycle Assembly Fuel Loading Waterhole and Shim Placement

Figure 3.1-c Fuel Assembly

Figure 3.1-d Fuel Rod

Figure 3.2-a Control Element Assembly Locations

Figure 3.2-b Full-Strength Control Element Assembly (4-Element)

Figure 3.2-c Full-Strength Control Element Assembly (12-Element)

Figure 3.2-d Part-Strength Control Element Assembly

Figure 3.3-a Posion Rod

Figure 3.3-b Core-wise Burnable Poison Placement

Figure 3.3-c Variation in K-inf. of Assembly to the Change of Burnable Poison Contents

Figure 3.4 Fuel Spacer Grid

Figure 3.5-a Fixed In-core Instrument Assembly

Figure 3.5-b Ex-core/In-core Detector Systems

Figure 4.4 MTC vs. Moderator Temperature at BOC, HZP-HFP, Eq. Xe, ARO

Table 4.5 Comparison of Core Reactivity CoefficientsMODERATOR

TEMPERATUREDENSITY

COEFFICIENTDOPPLER*COEFFICIENT

(/F 104)COEFFICIENT(/GM/CM3)

COEFFICIENTS FROM TABLE 4.3-4

Full power

BOC-0.52Figure 4.3-450.002

EOC-2.30Figure 4.3-45NA**

Zero power, CEAs banks 5,4

and 3 inserted

BOC-0.40Figure 4.3-45NA

EOC-1.78Figure 4.3-45NA

Figure 4.5 Fuel Temperature Coefficient

Figure 4.7 PSCEA Controlled and Uncontrolled Oscillation

Figure 4.8 Scam Worth vs. CEA Insertion

Figure 4.9 Daily Load-Cycle Maneuvering Transient at BOC (100-50-100%P, 0-8 Hrs)

Table 4.10 Comparison of Available CEA Worths and AllowancesCOMPARISON OF AVAILABLE CEA WORTHS AND ALLOWANCESREACTIVITY

CONDITION(% p)

All full-strength inserted, hot, 59419.02

Total reactivity allowance full power9.42

(from Table 4.3-6)

Stuck rod worth7.45

Uncertainty in net rod worth0.68

Excess reactivity1.47