ML20205K392

Fine Motion CRD Demonstration Test Description

ML20205K392
Person / Time
Site:	LaSalle
Issue date:	01/31/1986
From:	Lowton R, Villa R GENERAL ELECTRIC CO.
To:
Shared Package
ML20205K386	List: ML20205K383 ML20205K392
References
NEDO-31130, NUDOCS 8602270353
Download: ML20205K392 (37)

Text

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NEDO 31130 CLASSI DECEMBER 1985 l

LA SALLE UNIT 2 FINE MOTION CONTROL ROD DRIVE DEMONSTRATION TEST DESCRIPTION t

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88P 188s 888883u P PDP GEN ER AL h ELECTRIC

. NEDO-31130 Class I January 1986 IA SALLE UNIT 2 FINE MOTICE CCNTROL RCD DRIVE DDOETRATICN TEST DESCRIPTICN Approved: Approved: ,b.

R. Villa, Manager R. B. Iowton, Manager Products Licensing Japan ABWR Projects NUCLEAR ENERGY BUSINESS OPERATIONS

• GENERAL ELECTRIC COMPANY SAN JOSE CALIFORNIA 95125 GENERAL $ ELECTRIC

NEDO-31130 DISCEAIMER OF RESPCNSIBILITY Ihis h unant was prepared by or for the General Electric Ca pany. Neither the General Electric Coupany nor any of the ccntributors to this docunent:

A. Makes any warrantv or representation, express or inplied, with respect to the accuracy, cmpleteness, or usefulness of the information contained in this At v'==nt, or that the use of any information disclosed in this docunent may not infringe privately owned rights; or B. Assumes any responsibility for liability or damage of any kind which may result fran the use of any information disclosed in this document.

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NEDO-31130 I 1

l CCNTENTS l

1 Pace

1. INTRC00CTIN 1

2. MCRD DESCRIPTICN 2

3. MCRD SUPPORTING EQUIIHFNP DESuuvrIN 4 3.1 D CRD Electrical Controls 5 3.1.1 Operation Panel 7 3.1.2 Control Panel 10 3.1.3 Iccal Panel 11 3.2 DCRD Hydraulic Controls 11

4. PIANP KDIFICATICNS ET)R CRD REPLACDENT 12 4.1 Control Rod Drive and Housing Support 15 4.2 Hydraulic Control Unit 17 4.3 Booster Pressure System 17 4.4 Piping Syst m 21 4.5 Control and Instrumentation / Electrical Syst m 24

5. DCRD DDONSTRATIN TEST DESCRIPTIN 27

6. REACTIVITY CNTROL EVAIDATIN 29 6.1 Safety Analysis Review 29 6.1.1 Control Rod Withdrawal Error 29 6.1.2 Control Rod Drop Accident 30 6.1.3 Shutdown Margin 30 6.1.4 SCRAM Reactivity 31 6.2 Operations Review 31 6.2.1 Control Pod Mwement Control Systes 31 6.2.2 Rod Position Indication 31 6.2.3 Refueling Interlocks 32 ii

NEDO-31130 ILUJSTRATIWS Ficure Title Page 1, DCRD Schematic 3

? FNCRD Controls 6 3 DCRD Operation Panel 8 4 DCBD/LPCRD HCU Piping Interconnections 13 5 Booster Punp Configuration 14 6 DCRD ASME Section III Code Ccmponent 16 7a Existing LPCRD Housing Support 18 7b Replaced DCRD Housing Support 19 8 DCRD Hydraulic Control Unit P&ID 20 9 Booster Ptmp Flow Characteristics 22 10 Calibrated Flow Rate Through Booster Punp Versus 23 Orifice Pressure Drop 11 C&I/ Electrical Protection 25 111

NEDO-31130

1. INT!KDUCTICN A Fine Nation Control Pod Drive (DCRD) has been designed jointly by General Electric, Hitachi, and Toshiba for IMR application. It utilizes an electrically driven, screw actuated drive for shim motion with hydraulic action (i.e. , arv-ilator supplied) for scram moticm. It is proposed that an FNCRD denonstration in a reactor environment be performed at IaSalle County Station Unit 2. 'Ihe FMCRD's performance demonstration will be for one fuel cycle of an 18-nonth duration.

The FMCRD design has received considerable development and experience. It has passed extensive 40-yr equivalent life qualification tests. 'Ihe FMCRD un w i is currently in use in European BWR reactors. The particular DCRD

, intended for use at LaSalle Unit 2 has received a 7.5-yr equivalent life qualification before installation at tin site.

.For the DCRD &:mostration, a single FMCRD will be placed in a peripheral location of the rMalle Unit 2 core. In this low reactivity worth location, a red withdrawal error or a rod drop accident of this control red will result in peak fuel enthalpies less than the licensing basis 170 cal /am and 280 cal /can safety limits, respectively. Since the FMCRD position indicating systm is not ecurpatible with the plant's locking piston centrol rod drive (LPCRD) position indicating system, the DCio position will be bypassed fran the plant's rod pattern controls. When the rod pattern control system is enforcing rod pattern constraints, the D CRD will be fully inserted. 'Ihe "All' Rods Block" signal, such as fran refueling interlocks, will be enforced on the DCRD. Because the DCRD is in a peripheral location, the plant's rod drop accident analysis will not be affected.

The preceding highlighted DCRD design developtent and plant precautions are scme of the measures taken to assure a successful and safe DCRD in-plant denonstration. 'Ihe following is a further description of the DCRD, its supporting equipnent, plant modification required, and plant safety / operational evaluations.

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NEDO-31130

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2. DCRD DESCRIPTICN ,

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%e DCRD features low maintenance /high reliability and added plant I operational flexibilities. The DCRD is electrically driven for shim motion and hydraulically driven for scram rr.ation. Se main cmponents of the DCRD are the hollow piston, buffer springs, screw shaft, ball nut, unweighing detection assably, drive motor, and position synchres. 'Ihese major cmponents of the MCRD are shown in Figure 1.

Normal drive motion (or shim notion) is accmplished through an electrically powered stepping motor. Normal drive motion speed is 1 inch per second. Se stepping motor turns a screw shaft and a ball-nut assably translates the screw shaft's rotational motion to linear motion. We hollow piston, which is coupled to the centrol red, rests on the ball-nut assably.

Se ball-nut assably is not coupled to the hollow piston to allow the hollow piston to scram freely on denand. The ball nut's translational motion will lift the hollow piston when rod insertion is desired. When rod withdrawal is desired, the ballnut is retracted, which allows the hollow piston to withdraw by its own weight.

Upon receipt of a scram sianal, high pressure water fran the scram m=lator lifts the MCRD hollow piston away frcm the ball-nut assably and rapidly inserts the hollow piston and coupled control red. Water in the CPD is discharged into the reactor vessel. Disc springs buffer the rapid insertion at the end of red travel. When the hollow piston leaves the ball-nut assembly, two latches are camed out. mese latches will latch into notches located every 8 inches on the CRD guide tube when the CRD cmes to rest. Therefore, after scram empletion, the latches will hold the control rod in place at the full-in position. A drive-in signal is also received by the drive motor upon receipt of a scram signal. Within 2 minutes following scram initiation, the ballnut 2

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NEDO-31130 asserbly will: (a) catchup with the drive piston; (b) cane-in the latches; (c) support the control rod's weight; and (d) ccuplete notion to full insertion, if, for any reason, hydraulic pressure did not fully insert the red.

An unweighing detection assenbly will detect the loss of weight. due to a stuck control red and enforce a rod withdrawal block signal. The unweighing detection assenbly consists of a ugnet attached to a spring. When the spring rises ha-anaa of a loss of control rod weight, the magnet's movement changes the state of an external reed switch and causes a red withdrawal block sional to be enforced.

Fundamentally, the IJCRD differs frta the MCRD by utilizing: (a) hydraulic action for normal drive motion; (b) an external scram discharge for scram motion; and (c) scram capability with reactor pressure as a backup to the scram am=$1= tors.

In surmary, utilization of the HCRDs offers the following plant features:

a. Diverse means of rod insertion (electrical / hydraulic)

b. Control rod separation detecticn

c. Inproved plant maneuverability

d. Reduced CRD maintenance recuirement

3. FMCRD SUPPORTING EQUIPMENT DtKlumCN The DCRD utilizes both electric and hydraulic power sources. Normal drive notion is achieved through a stepping motor. 'Ihe stepping motor is powered by normal plant ac power via an inverter and its notor controls. Rod position 4

, NEIX>-31130 information is supplied by redundant synchro transmitters. The scram motion is achieved through the stored energy of a hydraulic accumulator. The hydraulic a m =nlator's charge is maintained by the existing plant's CRD hydraulic supply systesu and a booster pressure system. A description of the FNCFD's normal drive and scram controls is given in the following subsections.

3.1 MCRD ELECTRICAL CCNTROLS The MCRD electrical control for the plant demonstration consists of three major panels and information links between the MCPD, its hydraulic control unit (HCU), the plant's Control Rod Drive System (CRDS) and the plant's Reactor Protection Systen (RPS) . 'Ihe discrete hardware and the information which passes between them is schematically illustrated in Figure 2.

'lhe Operation Panel provides the operator interface. Frcm this panel, the -

operator makes MCRD movement requests and receives indication of the system's status.

The Control Panel is the main controller of information. It ccumunicates with the MCRD Operation Panel, the ENCRD Iccal Panel, the plant's RPS and the

, plant's CRDS. All logic operations are performed at this panel. In addition to operating on inccming signals, the Control Panel receives power frexn the plant and distributes it to the Operation and Iccal Panels.

'1he Iccal Panel receives inccming control signals and ac power frcm the Control Panel. The ac power is converted into appropriately modulated de power to drive the stepping motor. The Iocal Panel also passes FNCPD position and other sensor data to the Control Panel.

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NEDO-31130 3.1.1 Operation Panel The Operation Panel's layout is illustrated in Figure 3. Frm this panel, the operator selects and initiates step or continuous rod novement emmands.

The IJ!D indicators display both the current and target positions. In addition to accepting operator camands, several annunciators notify the operator of the system's status.

The DCRD is r apable of moving in nultiples of 1, 5, 25, 50 and 100 of the 3-am base i h _ A. To operate the drive, select the desired ntnber of iru _ _.ts fr a the " Step Ntaber Set", depress and hold the " Insert" or

" Withdraw" pushbuttons and select the " Continue" pushbutton. When insertion is required and it is r=e====q to override the system timer, an "Bnergency Insert" switch is available. If the red needs to be decoupled for mnintenance, then the keylocked overtravel switch nust be turned to " Permit" to allow operation of the drive in the overtravel region.

The Operation Panel contains several indicators designed to give the operator a cmplete picture of the DCBD's status. '1he most inportant of these are described below:

a. Current Position Indicator. An LED indicator displays the red's current position in millimeters as obtained frm the synchro transnitter. During continuous driving, the indicator follows the red's nDVERWnt.

b. Target Position Indicator. A similar LED indicator dieplays the i operator selected target position. 'Ihe target position is the sum of the current position and the selected step. When the red is stationary or is following a scram, this indicator does not display any values.

c. Accunnlator Trouble. An "N r'milator Trouble" indicator activates when the a<-r'=ilator's nitrogen pressure is low or its water level is high. Overpressure from the booster punp discharge also actuates the Accunulator Trouble indicator.

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d. Drift. If the drive moves down without receiving a withdraw signal, the drift iniicator activates.

e. Control Panel Trouble. The " Control Panel Trouble" indicator activates if a circuit fails or another abnormal condition is etected.

f. Iccal Panel Trouble. The "Iccal Panel Trouble" indicator activates if an inverter fails or other abnormal condition is detected.

g. Full-In. " Full-In" indication results when the red reaches O m.

h. Full-Out. " Full-Out" indication results when the rod reaches 3660 m (144 in.) .

i. Overtravel. An " Overtravel" indicator activates when the drive is being operated below the " Full-Out" position,

j. Separation. When the rod separates frre the ball nut, the

" Separation" indicator activates.

k. Scr a Cenplete. "Scra Cmiplete" indication occurs when a sucm.d red reaches the full-in position.

1. Scram. Following manual or autcmatic scram, a " Scram" indicator activates.

m. Scram Following. Until the ball nut reengages with the rod, the

" Scram Following" indicator activates after a scram,

n. Uncouple. " Uncouple" indication results when the rod is decoupled in the overtravel region.

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NEDO-31130 3.1.2 Control Panel The Control Panel provides the necessary logic to execute operator

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The operator initiates drive mtion frm the Operation Panel. After the motor stops, the rod cannot be moved out of the core again for 3 seconds. The system autmatically resets itself after the 3 seconds have elapsed.

In addition to its fine m tion capability, the operator can insert or withdraw a rod continuously. Once again, when the rod stops, mvenent is inhibited for 3 seconds.

If at any time the "Bnergency Insert" pushbutton is depressed, all other ongoing operations, with the exception of scram, are terminated, and the red is driven into the core.

Autmatic scram sianals originate fran the plant's RPS. Upon receipt of such a signal, the red scrams, via hydraulic pressure. Simitaneously, a " Scram Follow" signal is issued to the stepping motor. The motor responds by driving the ball nut until it reengages with the rod.

When both the " Manual Scram A" and the " Manual Scram B" pushbuttons on the min control rom panel are depressed simultaneously, the scram pilot valve is deenergized, and the MCRD scrams (along with all the other CFDs) . This state is held by a self-hold circuit. 'Ib reset the system, the Scram Peset Switch on the main control rom panel must be sequentially rotated fran its normal position to Group 1/2 and to Group 3/4 positicms and back to normal.

When the rod reaches 3660 mn (144 in.), a full-out reed switch closes and issues a red withdrawal block signal. To uncouple the rod for maintenance purposes, the drive must be moved to 3728 mn (147 in.) . To allc=4 such a movemnt, the overtravel switch is positioned to " Permit". By so doing, this 10

NEDO-31130 switch bypasses the inhibit signal frm the synchro position transmitter and the rod withdrawal block frm the full-out switch. Since the over-travel region is not a nultiple of the base increment, step motion cannot be used.

3.1.3 Iccal Panel

'Ihe local panel nrvblates motor driving power according to inconing operation instruction signals. Motor driving power is processed via a converter and inverter unit. 'Ihe converter unit requires 115V + 10%-15%, 60/50 Hz input i voltage and outputs of 5,15, or 24V DC voltage to the inverter unit. 'Ihe inverter unit provides pulses of variable voltage and current for stepping motor actuation according to control signals danands.

3.2 DCRD HYDRAULIC COrrROLS

'Ihe primary function of the DCRD hydraulic controls is to scram the control rod upon demand. A second function of the FNCRD hydraulics is to provide cmtinuous CRD purge water flow. The DCRD hydraulic controls are performed at its HCU.

The MCPD HCU is similar to the present locking piston centrol red drive (LPCPD) HCU. 'Ihe DCPD HCU's nitrogen and water bottles are larger than the LPCRD HCU's bottles, but the DCRD HCU has no directional control valves, nor a

< cram discharge valve. Since the MCPD is electrically driven, the DCPD's HCU has no need for the hydraulic drive directional controls required by the LPCFD for shim notion, and the directional controls for LPCRD 02-43 are bypassed.

During scram, the DCRD discharges into the reactor vessel. 'Iherefore, the conventional LPCFD scram discharge valve, piping, and discharge voltzne are not required. With the elinination of the external CFD discharge volume, the DCRD nust scram against reactor pressure. Since the DCRD scrams against reactor pressure and allows greater CFD leakage flow, a scram accunnlator that is larger than the LPCPD is required. Operatic n of the scram pilot solenoid valve by the 11

NEDO-31130 Beactor Protection System (RPS) is identical to that of the LPCRD. The scram ammilator charging and CRD purge flow is provided by the plant's CPD hydraulic supply system. We DCRD purge flow rate requirements are identical to the LPCRD cooling flow rato requirements. Figure 4 illustrates the DCRD/LPCRD HCU piping interconnections for LPCRD Position 02-43.

As previously discussed, the DCRD requires greater scram acctmulator energy than the LPCRD. Se FNCRD am_=ilator would be charged to a higher final pressure than the typical BWR-5 (LaSalle class) LPCRDs. However, the plant's CRD hydraulic supply system cannot supply the additional charging pressure desired for the DCRD accumulator. The DCRD hydraulic nodification would include a booster pressure system (i.e., small booster punp) to charge the DCRD ammi1= tor up to 1700 psig at rated reactor pressures. The increased pressure would be adequate for the DCRD to ccmply with the plant's scram time surveillance requirements. Figure 5 shows the booster punp configuration.

Further discussi<m of the n4CFD's scram time requirenents, given its peripheral location, is presented in Section 6 of this report.

The DCFD's HCU piping will be tied into the present LPCFD's ICU. The LPCRD's insert and withdrawal lines will be used by the DCRD as scram insert lines. The LPCPD's HCU accunulator charging and cooling flow functions are extended to the DCRD's FCU. The scram pilot solenoid valve's power will also be extended in conduit to the DCFD HCU. We scram pilot solenoid valve's power will also be extended in conduit to the DCRD's HCU frtxn the LPCR's HCU.

4. PIANT MCDIFICATICN EUR CRD PEPIJCDENT The existing Iocking Piston Control Rod Drive (LPCRD) at the peripheral core location 02-43 of the LaSalle Unit 2 reactor will be replaced with a Fine fetion Control Rod Drive (DCRD) for a duration of one fuel cycle. To facilitate this replacement, certain plant modifications are required. The u.ugrents/ systems affected in these nodifications are the Control Rod Drive, hydraulic control unit, boonter punp, piping, CRD housing support, and control and instrumentation / electrical equipnent.

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NEIX)-31130 This section describes the plant modification design and its emnliance with the applicable Codes to assure that no adverse effect will be introduced into the Balance of Plant as a result of the modifications.

4.1 CNTROL RCD DRIVE AND HOUSING SUPPORT

'Ihe LaSalle Unit 2 Control Rod Drive replacanent is based on the requirements of the ASME Boiler and Pressure Vessel (B&W code),Section XI, 1980 Edition, winter 1980 Addenda, specifically, INA-700 and IWB-700. The Code itens of the existing LPCRD were designed and fabricated in accordance with the requi~ unents of the ASME B&W Code,Section III, Class 1 Appurtenance,1971 Edition and Code Case 1361. The Code itens of the FNCRD are designed to the requirements of Snhaar-tion NB of the ASME B&W Code,Section III,1980 Edition, winter 1980 Addenda, for Nuclear Power Cupe_nts Class 1 Appurtance.

The Code itens of the DCRD were fabricated by Hitachi, Ltd. (an NPT Certificate Holder) and analyzed by General Electric Cmpany in accordance with paragraphs NB-2000 and NB-3000 of the ASME Code, respectively. These Code iterns (shown in Figure 6) include middle housing, lower housing, seal housing, shaft nut, bolts and nuts. All of these Coded itens have been designed, analyzed and fabricated as safety-related ccuponents. The ENCRD drive shaft and seal package are exatpted frun the rules of the ASME Code NB-3400 as Code items based on the similarity to the pop shaft functional application.

The hydrostatic test of the MCRD asserbly has been performed at the Engineering Test Facility of the Generrd Electric Capany (San Jose, California) in accordance with paragraph NB-6000 of the ASME Code,Section III,1980 Edition, winter 1980 Addenda. As a replacanent, the FNCRD assetbly is exenpt from the requirement of the application of the AEME NPT Stanp symbol (Section XI, Division 1, 78-80 interpretation).

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NEDO-31130 The existing CRD housing support structure for the replaced LPCRD needs to be modified to aw-- < late the MCPD, since the FNCRD motor and spool piece extends apprnximately four (4) feet beyond the LPCFD flange. This modification involves renming the LPCPD 02-43 housing support hardware and replacing it with four parts of MCPD hardware as shown in Figures 7a and 7b. The design and l

fabrication of the MCPD housing support structure will be treated as a safety-related cww#.nt.

4.2 HYDRAULIC CCNTROL UNIT The ammilator and the nitrogen cylinder of the FMHCU unit are both classified as essential to the safety of the plant in accordance with 10CFR50, Appendix A. The hydraulic control unit, when assenbled as part of the control rod drive hydraulic system, beccanes a part of the pressure piping system. The MCRD unit to be applied at LaSalle-2 has been designed, constructed and inspected per the applicable Code (s) requirements.

The am=ilator and nitrogen cylinder meet the requirements of the ASME Boiler and Pressure Vessel Code,Section VIII, Division 1. The renairder of the HCU equipnent (i.e., piping, valve, fitting, flange, bolts and plug) is classified as ANSI B31.1 power piping equipnent. This Code boundary definition is identical to that of the replaced locking piston HCU unit. Figure 8 illustrates the FM HCU unit piping and instrunent diagram (P&ID) .

4.3 BOOSTEP PRESSURE SYSTEM The FMCRD in-plant test would require a booster pressure system to charge the MCFD am=ilator to 1700 psig at rated reactor pressures. As shown in Figure 5, the booster pressure unit consists of cne air-operated booster pump with a maximum coerating pressure of 3000 psig. The pump will operate on 60-100 psig instrumnt air and will have a boost ratio of 30 to 1.

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NEDO-31130 In other words, a 1 psig air pressure is required to increase the charging pressure to 30 psig. The pmp characteristics of flow versus charging pressure are plotted in Figure 9. As shown in this figure, the booster pm p operates with a relatively small flow rate. The max 2n n flow rate is less than 1.5 GPM.

Se booster puup unit to be installed at IaSalle-2 has been successfully operated at General Electric and hydro-tested at 3000 psig. In an unlikely event of h-in. d4=ater charging line break, double isolation valves 107 and 113 can be manually closed. To add further protec+ don, an ex ss flow check valve will be insta11ad imediately after the charging water valve 107. His valve can be adjusted to shutoff autmatically when the flow rate exceeds 5 to 10 GPM range. Flude ->re, to prevent exmssive flow rate through the pap and causing flow shutoff (through the excess flow check ulve) after a scram, a small orifice is installed at the ptmp exit. Imer" aly after a scram, a maxian pressure differential of 1000 to 1500 psig tcross the ptmp could occur. Figure 10 shows the talibrated flow rate versus the pressure drop across a 0.07-in.

diameter orifice. The flow rate is limited to less than 4 GPM under any operation cirematance.

To provide additional protection to the Balance-of-Plant equipnent, a pressure relief valve is installed at the die %=rge, and a high pressure alarm is econected to the E?CRD operating panel via FNCRD HCU low pressure alarm annunciator. Thus, ywiection against both the booster pmp pipe break and HCU systen overpressurization is provided.

4.4 ENHCU PIPING SYSTEM The ENHCU piping systen connecting the existing HCU 02-43 is designed in accordance with ANSI B31.1 Piping Code. 'Ihis system includes 1-in diameter and 1%-in. diameter insert lines, -in diameter charging water line, -in. diameter instr m ental air lines and associated valves and tees. The insert lines, main 21

NEDO-31130 AIR PRESSURE lasil E ~

00 100 90

' =

1000 w

I w

E 5io00 -

• E 5

4 000 - *

' adOOEL SC 448001.75 Sl HO4 I i i o c.s 1.0 1.s 2.0 FLOW R ATE (gaml Figure 9 Booster Pump Flow Characteristics i

22

NED0-31130 teoD 1000 =

E t

8

.00 -

0.07-in. den pmone ORIFICE 800 STER r ~

Punse lV TO HCU

, a e i i 1 0 1 2 3 4 s FLOW RATE (spel Figure 10. Calibrated Flow Rate Through Booster Pump Versus Orifice Pressure Drop 23

NEDO-31130 isolation valves and reducers are to be procured as safety-related cmponents.

All piping caponents are classified as non-safety related but seismically supported.

4.5 CCNTPOL APO INSTRENENTATICE (C&I/ ELECTRICAL SYSTEM) h C&I/ electrical design of the ENCRD in-plant test has been configured to minimize the amount of modifications and inpact upon existing plant systems and equipnent. Referring to Figure 11, a sinplified block diagram, it can be seen that the C&I/ electrical equipnent for the EEPD in-plant test, to a large extent, stand alone with a minimtan nuiter of interfa s with existing equipnent.

Furthermore, the limited physical and functional interfaces which do exist are configured to assure that any potential faults within the EERD in-plant test equipnent will not have adverse impact on the existing systems and equipnent.

These equipnent svifction functions are as follows:

a. Power to the EERD controls is provided finn power distribution panel PCC-1324-2. h se power connections are protected both in the power distribution panel with circuit breakers and in the ENCRD Control Panel with fuses,

b. The EERD Control Panel receives a Pod Withirawal Block signal from the Peactor Manual control System (BPCS) . This signal originates fran relay contacts in the PMCS Rod Drive Control Cabinet (H13-P616) and, therefore, provides fault propagation protection through the inherent relay coil to contact separation.

c. The Peactor Protection System cabinets (H13-P609 and H13-P611) provide scram initiation signals to the EERD Control Panel. Like the general red withdrawal block signal fran the BMCS, the PPS trip signals originate at 24

ExlSTING LPCRO = r NEW PMCHO EW N ENT SOUIPMENT I

NR .

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REACTOR PANEL 4_ . _ __ _ L '_20 1ac_ OPERATION

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CASINET (M13 P00SI (M1 M g143 r - - - - - - --'

' RPS 5 TRIP SIONAL ROCS d useNG TwE Existing SYPASS CAPASILITIES. I Il h LOGIC PANEL POS4TlON INFORMATION g !

(M1MWS) P e FOR LPCRD 02 43 WILL sEeYPAa8EDPROM THE RSCS LOGIC li y I

ROO POsmON I l, goag h INFORMATION l pgggg gl IH1 M 003)

' - * ' CASINET (M1MG1Si lg

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l l CAslNET E=d LEGEND OF ELECTRICAL (M1 M etti PROTECTION METHOOS:

A BREAKER PLUG IN CONNECTOR FOR E RELAY POSITION IMOICATING

1. ROSE ON THE LPCRD \

WHICH HAS SEEN REMOVED I l,l 8 PUSE I e g a i

C i I PMCR0 2 MOTOR Figure 11 C&I/ Electrical Protection 25

NEDO-31130 relay contacts so that the MCRD equipnent is isolated frm the RPS throuch inherent coil to contact separation. (As an aside, this design is exactly like that used to provide the scram trip indication signal to the non-essential plant annunciator system).

d. 'Ihe last area of interface is the PPS electrical power to the scram solenoid valves on the new MCRD Hydraulic Control Unit (HCU) . These new power cables originate at the existing HCU for the CRD at position 02-43 and run over to the new MCRD HCU in protective conduit. At their termination point at the new MCRD HCU, an in-line fuse provides protection just exactly like in the existing HCU. In this arrangement, the new MCRD ICU suustion provides the same fault propagation protection as that afforded by all the other HCUs in the plant.

With the rep 1-nt of the LPCRD with the new MCPD, at core position 02-43, all cmtrol and feedback signals for the DCTO are provided through the new dedicated MCRD control panels. The rerreval of the LPCPD at 02-43 is am--- hted in the interfacing systans so as to have no inpact or require any permanent equipnent modification. These relatively minor reconfigurations are a follows:

a. Since the position indicating probe (PIP) in LPCRD is renoved with the LPCUD itself, there is no input to the PMCS Pod Position Information System, and the Reactor Control Panel display will show the CRD at 02-43 to have a default indication.

l

b. Using one of the eight bypass switches provided, the CRD at position 02-43

~

will be bypassed (i.e.', renoved) frm the PSCS rod pattern control logic.

c. All the electrical vuustions to the directional control valves on the existing LPCRD HCU at 02-43 will be left as is, but the valves themselves will be hydraulically isolated through the closure of the manual maintenance valves, which are adjacent to these valves. With this 26

NEDO-31130 configuration, the modification of existing equipnent is kept to a mininum, and there is no adverse inpact in the event that the operator initiates movment of control rod 02-43 from the existing main Peactor Control Panel (H13-P603).

d. Renove the LPCRD HCU 02-43 cooling water valve V104 wedge and replace with an orificed wedge to provide metered cooling flow to MCRD.

e. Marnuelly adjust the scram inlet valve (V126) to the fully closed position to prevent backflow during scram.

In stminary, all the required interface mechaniral and electrical m -icdons include sufficient protection to assure that no faults in the new DCRD test agn4==rtt propagate back into the rest of the plant equipnent to which it is directly or indirectly mu=icced.

5. DCRD DEMENSTPATIN TEST DESCRIFfICN It is proposed that a DCRD and its supporting equignent be installed at LaSalle Unit 2 to observe and denonstrate the operations of the DCRD in an operating plant environment. It is anticipated that the test will last for the

duration of one plant fuel cycle. During reactor installation and removal of the DCPD, handling methods, maintenance promhtres, and radiation levels will be doct-eited.

The following scheduled pre-operational tests will be performd following reactor installation to cc . firm its proper operations:

a. Friction hst

b. Coupling Verification Test

c. Functional Test (1) Drive Speed 27

NEDO-31130 (2) Stepping (3) Scram

d. HCU Test (1) "A" and "B" Circuit 'Ibst (2) High Pressure and Im Pressure Alarm Test During reactor operations, the following data will be maintained by Plant Operations:

a. A brief statement of MCPD operational history and reactor operating history every 6 months. Any abmma14 ties in MCPD operation will be noted.

b. Typical traversing in-core probe (TIP) trace of TIP Probe nearest to MCRD during control rod pattern change using MCPD at least twice during the fuel cycle.

c. Peactor parameters such as thermal output, core flow rate, reactor l

pressure, and subcooling during the subject pattern change should be l

included in the preceding its (a) and during item (b) .

At the conclusion of the plant demonstration, the drive shall be renoved fran the reactor pressure .ossel and disassembled. All parts shall be visually examined for signs of wear, corrosion or other damage. Parts showing signs of damage or excessive wear shall be doct..ed.ed in a report and depicted by fiW%.gi, sketch, or dimensional inspection, if judged appropriate by the Test Director.

28

NFDO-31130 Additionally, during the final disassembly and inspection, operating FNCRD radiation levels will be determined and categorized. Dose rates before and after washing will be recorded.

- At the conclusion of the pcot-d_ -Lation exanination, radioactive portions of the drive shall be diam =ad of in accordance with the site Other drive - v-.-is and electrical panels shall be either y -- t. =s.

retained or di=m==d of by mutual agreenent between the Canonwealth FA4m empany and the General Electric Cenpany.

i

6. RIDCTIVITY CCNTROL EVAIDATIQ4S ner.muna the 190D operates differently and is separately instn- _ Red frun the IJCIce, it is necessary to verify that all reactivity ocntrol requirements 4 will be met with r +-t to the Tah11e FSAR and Technical Specifications and to determine prmartwal changes needed to accamodate the P?OD. 'Ihe reactivity control evaluations are divided into safety analyses and operational evaluations.

6.1 SAFETY ANALYSIS REVIBf

', 6.1.1 control Rod withdrawal Error The P? O D rod will be installed in a peripheral location at Position 02-43.

Because of this location, analysis has shown that its maximaan worth will be less than 0.5% k/k in the startup range. 'Iherefore, withdrawal of the PMCRD rod will not significantly increase power or fuel enthalpy during startup. Under hot conditions, the rahlla FSAR and Technical Specifications state that the Rod Block Monitor (REM) autcentically bypasses peripheral rods, confirming their uninportance in rod withdrawal error (RWE) and MCPR analyses under hot conditions. As stated in the LaSalle FSAR, a possible RWE event occurring during refueling is not considered feasible and is not evaluated. In addition, shutdown margin requirenents will ensure that the reactor will remain suberitical with the highest worth rod and the P?cD red withdrawn, making an PWE event involving the P?OD rod during refueling of no significan . In sunnary, the low reactivity worth P?CPD rod will have very little effect on peak fuel enthalpy and m.

29

NEDO-31130 6.1.2 Control Rod Drop Accident The design of the ENCFD System greatly reduces the probability of a centrol rod drop accident (CRDA) . 'Ihe EERD is equipped with a control red separation (unweighing) detection system which detects the reduced weight m the drive should the control rod became stuck in the core. Drive withdrawal movement will be autanatically terminated the instant the rod beccmes stuck and, thus, prevent the control red fran potentially dropoing fran full-in to full-out. Analysis has shown that, if the EEPD is moved out of sequence and adjacent rods are witMrawn, the effect on the CRDA analysis is negligible.

The peripheral location of the EMCRD rod will cause it to have a very low reactivity worth such that the resulting peak fuel enthalpy in a CPDA would be far below the 290 cal /gn safety limit. Also, while the EERD rod will be bypassed in the Rod Sequence Control System (RSCS), it will be administratively treated as an inoperable rod. It will be moved only after the withdrawal / insert sequences of its Banked Position Withdrawal Sequence group are ccmplete, thus staying within the analyzed red pattern constraints for inoperable rods.

It is concluded that: a CRDA event involving the ENCRD rod is of no consequence because of its peripheral locaticm.

6.1.3 Shutdown Margin Because the E E RD rod is in a peripheral location, where its worth has been calculated to be less than 0.5% k/k, shutdown margin can still be met with the EERD red and the 5L.ugst worth red fully withdrawn at the limiting point in the cycle. 'Ihe 1% k/k design shutdown margin provides assurance that the 0.38 k/k Technical Specification shutdown margin will be met throughout the cvele.

As a result, all shutdown nargin requirements will be met during the second fuel cycle.

30

NEX>-31130 6.1.4 Scram Peactivity Bounding analyses have been performed which demonstrate that the failure of the ENCRD to scrm has a negligible irrpact on the plant's scram reactivity insertion rate. These analyses asstmed that the highest worth, adjacent control rod drive also failed to scram. '1herefore, the MCRD need not be declared inoperable because of potentially excessive scrm 1. Mon times.

6.2 OPERATICNS REVIEN

'Ihe FNCRD rod will be treated as a special demonstration, and special test exceptions will be requested to exenpt it fran the existing Technical Specification requirements. Be< anaa of the low reactivity worth associated with the peripheral location of the MCRD red and the justification provided by the above evaluation, it is concluded that this special exception does not affect reactor operations or accident analyses and will not reduce the margin of safety as defined in the basis for any IaSalle Unit 2 Technical Specifications.

6.2.1 Contrni Rod Movement control Systes The MCRD red position, 02-43, will be bypassed in the RSCS and picy urd out of the red worth minimizer (Met) . '1his will free the MCRD red frein Banked Position Withdrawal Sequence (BPWS) and notch movenent restrictions. The PMd is automatically bypassed for peripheral red locations such as 02-43 and will, therefore, be unaffected.

6.2.2 Rod Positicm Indication The MCRD rod position indication will be independent of the plant's Pcd Position Information System (PPIS) . Under normal operation, the MCPD red will have position indication over 100% of its range of movement at the MCRD 31

NEDO-31130 Operation Panel. '1he DCRD will not be moved until reactor power is greater than 25% and a rod pattern has been established. For SCRAM surveillance testing, it will have separate reed switch type position indication to verify SCRAM pesfemussce.

6.2.3 Refueling Interlocks The refueling interlocks system will not receive a " rod-in" signal when the DCRD red is irwLed during refueling. A apacial administrative procedure will be in place to ensure that the M CRD zod is full-in before the signal to the refueling interlocks systems can be jumpered to indicate full-in. 'the refueling interlocks system will not allow refueling bridge novement or withdrawal of any other control red if the M CRD red is not indicated full-in. '1his procedure will make claar that the full-in signal can be jtmpered only if the refueling bridge movenent or control rod withdrawal is necessary. 'Ihe procedure will include disarming the MCRD by di.+.uu=5cdng the power supply to the electric motor to prevent inadvertent withdrawal during refueling.

i l

l 32

_ _ _ _-_ __ _ _.