ML20126L521

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Rev 2 to TMI-2 Div Sys Description for Dewatering Sys for Defueling Canisters (ECA-3255-84-0087)
ML20126L521
Person / Time
Site: Three Mile Island Constellation icon.png
Issue date: 06/06/1985
From: Mays R, Ril C
GENERAL PUBLIC UTILITIES CORP.
To:
Shared Package
ML20126L518 List:
References
15737-2-M72-DS, 15737-2-M72-DS0, 15737-2-M72-DS01-R02, 15737-2-M72-DS1-R2, NUDOCS 8506200028
Download: ML20126L521 (20)
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Text

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2 ISSUE DATE 00 ITS O NSR O NITS TMI-2 DIVISION SYSTEM DESCRIPTION FOR Dewatering System for Defueling Canisters (ECA-3255-84-0087)

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Nuclear 15737-2-x72-DS0i Tme TMI-2 Division System Description for Dewatering PAGE OF System for Defueling Canisters 2

20 Rev.

SUMMARY

OF CHANGE 1

Added section 3.7.3 (pg. 3); Added ref. 23-30, changed ref. 7, clarified ref. 2, 5 and 22 (Sect.1.2); Added V016A/B and bypass spool l

piece para., updated relief valve para., and venting to SDS offgas, changed " flapper" to " paddle" in reference to sightslass (Sect. 1.3.1);

i Deleted breather vent filter, updated pump and crane info. (Sect.

1.3.2); Changed pressures (Sect. 1.4); Added sentence on location of controls (Sect 1.5 and 1.6.1); Changed "reachrods" to " extension stems", added sentence on V047 (Sect. 1.5 and 1.6.2); Changed HS-9A/B to HIS-9A/B (Sect. 1.6.1 and 3.3.5); Added "after dewatering and also i

prior to shipping" (Sect. 1.6.4); Clarified venting in item 1 (Section j

1.7); Changed cover gas pressure (Sect. 2.1 and 3.3.3); Added sentence for R-3 and "above the bottom of the tank" (Sect. 2.2); Added "to the holdup tank (T-1), which in turn is vented" (Sect. 2.3); Added para. on dewatering last canister, changed initial pressure (Sect. 3.3.2.1);

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Changed initial pressure (Sect. 3.3.2.2); Changed V004A/B to V016A/B l

(Sect. 3.3.6); Deleted valve V026 (Sect. 3.4); Added sentence for i

transfer and drain lines (3.5); Changed " flapper" to " paddle" (Sect.

3.7.1); Changed "15" to "13" and "SDS offgas system" to " holdup tank" (Sect. 3.7.2); Added section 3.7.3; Deleted item 6 (Sect. 4.1, 4.2, and 4.3); Changed " color coded" to "different sizes" and "approximately four" to "several", deleted sentence on location (Sect. 7.0).

2 Added "V002A and V002B", sentence on filter pressure drop, jib crane i

information, information on tank effluent concentration and dilution, "V041", the design pressure and temperature, deleted information on j

argon manifold meeting CGA standards, changed " recirculation" to i

"backflush" (Sect.1.3.1); Added " Division I, Part UW (lethal) (1983)"

I (Sect 1.3.2); Added "V002A and V0028," "V041," and "V017" (Sect.

I 1.6.1); Deleted phrase about V047 having a standard handle (Sect. 1.5 i

and 1.6.2); Added "V017", changed "inside to "at" (Sect. 1.6.4); Added fifth system-interface (Sect. 1.7); Added "V002A and V002B" (Sect.

3.3.2.1, 3.3.2.2, and 3.3.6); Added filter canister differential pressure limitation and minimum weight loss (Sect. 2.1); Added effluent i

I concentration information (Sect. 3.3.5); Revised the second sentence (Sect. 3.5); Changed leak criteria (Sect. 3.3.6); Deleted sentence on opening V025 to backflush, added sentence on how backflush line is I

filled (Sect. 3.7.1); Revised rewetting method (Sect. 3.7.3); Changed j

"six" to "five", moved "and" (Sect. 4.1).

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15737-2-M72-DS01 Table of Contents

'1.0 Design Description 1.1 Summary 1.2 References 1.3 Detailed System Description 1.3.1 Description 1.3.2 Major System Components 1.4 System Performance Characteristics 1.5 System Arrangement 1.6 Instrumentation and Controls 1.6.1 Controls 1.6.2 Valves 1.6.3 Power 1.6.4 Monitoring 1.6.5 Lights 1.6.6 Trips and Interlocks 1.7 System Interfaces 2.0 System Limitations, Setpoints, and Precautions 2.1 Limitations 2.2 Setpoints 2.3 Precautions 3.0 Operations 3.1 Initial Fill 3.2 Startup 3.? Normal Operations 3.3.1 Pre-Dewatering Checkout Requirements 3.3.2 Canister Dewatering 3.3.2.1 Filter Canister Dewatering 3.3.2.2 Knockout and Fuel Canister Dewatering 3.3.3 Canister Gas Covering 3.3.4 Post Covering Checkout Requirements 3.3.5 Transfer to DWC 3.3.6 Canister Pressure Check 4

3.4 Shutdown 4

3.5 Draining 3.6 Refilling 3.7 Infrequent Operations 3.7.1 Backflushing 3.7.2 Canister Pressure Reduction 3.7.3 Rewetting Filter Medis 4.0 casualty Events and Recovery Procedures 4.1 Casualty Events 4.2 Design Features to Mitigate Effects of Casualty Events 4.3 Recovery Procedures 5.0 Maintenance Page 3 Rev. 2 0196Y

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15737-2-M72-DS01 6.0 Testing 6.1 Hydrostatic Testing 6.2 Instrument Testing 6.3 Periodic Testing 7.0 Human Factors Page 4 Rev. 2 0196Y

15737-2-M72-DS01 i

I 1.0 Design Description j

1.1 Summary The Dewatering System is a recovery system which removes and filters the water from submerged defueling canisters and provides a transfer path to the Defueling Water Cleanup (DWC) system for processing.

i The Dewatering System also provides the cover gas for canister I

shipping.

The water is removed from the defueling canisters to 1) reduce the weight of the canisters for shipping, and 2) prevent the hydrogen /

oxygen catalysts from being submerged. The cover gas of argon is provided to 1) reduce water intrusion when the canister is in the water, 2) reduce air intrusion when the canister is out of the water, and 3) reduce the pyrophoricity potential of the debris within the canister.

1.2 References 1.

Bechtel Drawing 15737-2-M74-DS01, Piping and Instrument Diagram-Dewatering System l

2.

Bechtel Drawing 15737-2-P60-DS01, Piping Isometric-Dewatering System, Fuel Handling Blds. F1. El. 347'-6" 3.

Bechtel Drawing 15737-2-P0A-6401, General Arrangement-Fuel Handling Building Plan E1. 347'-6" 4.

Safety Evaluation Report for Defueling the TMI-2 Reactor Vessel,

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Doc. No. 15737-2-G07-107 7

5.

Bechtel Drawing 15737-2-COP-6201, Dewstering System Platform i

6.

Bechtel Drawing 15737-2-C64-DS01, Pipe Supports for Isometric 15737-2-P60-DS01 7.

DCN No. 2R-950-21-001-5-5, P&ID Composite-Submerged l

Domineraliser System

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8.

Instrument Index, Doc. No. 15737-2-J16-001 9.

Design Engineering Valve List, Doc. No. 15737-2-P16-001 l

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10. TMI-2 Recovery Mechanical Equipment List, Bechtel North American i

Power Corp., Job 15737 l

11. Standard for Piping Line Specifications, Doc. No. 15737-2-P-001

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12. Piping Line Inder, Doc. No. 15737-2-P-002 I

13.

Intermediate Evaluation of Special Safety Issues Associated with l

Handling the TMI-2 Core Debris, prepared by Rockwell Hanford l

Operations, Document No. SD-WM-TA-005.

I Page 5 t

Rev. 2 0196Y I

_ _ _ _ _. _ _ ~, _

15737-2-M72-DS01

14. Bechtel Drawing 15737-2-J78-DS01, Level Setting Diagram
15. Bechtel Drawing 15737-2-J74-DS01, Instrument Installation Detail
16. Bechtel Drawing 15737-2-J74-DS02, Instrument Installation Detail
17. Bechtel Drawing 15737-2-E76-DS01, Pump Schematic Diagram
18. Bechtel Drawing 15737-2-J77-DS01, Pump Logic Diagram
19. Bechtel Drawing 15737-2-EOR-6401, Fuel Handling Building EL.

347'-6" Electrical Physical Drawing

20. Bechtel Drawing 15737-2-E21-010, Single Line Diagram
21. ECA-3221-84-0111 Standby RC Pressure Control (SPC) Surge Tank Removal
22. ECA-3255-84-0087 Dewatering System Design
23. Bechtel Drawing 15737-2-P60-DS02, Piping Isometric - Dewatering Systes, Dewatering Canister Inlet and Outlet Piping
24. Bechtel Drawing 15737-2-P60-DS03, Piping Isometric - Dewatering Systes, Offges & Sample Piping
25. Bechtel Drawing 15737-2-P60-DSO4, Piping Isometric - Dewatering System, Tank DS-T-1 Connections and Miscellaneous Details
26. Bechtel Drawing 15737-2-P60-DS05, Piping Isometric - Dewatering System, Argon Supply Piping, Fuel Handling Bids. Pool "A"
27. Bechtel Drawing 15737-2-C64-DS02, Pipe Supports for Isometric 15737-2-P60-DS02.
28. Bechtel Drawing 15737-2-C64-DS03, Pipe Supports for Isometric 15737-2-P60-DS03.
29. Bechtel Drawing 15737-2-C64-DSO4, Pipe Supports for Isometric 15737-2-P60-DSO4.
30. Bechtel Drawing 15737-2-C64-DS05, Pipe Supports for Isometric 15737-2-P60-D605.

1.3 Detailed System Description 1.3.1 Description The Dewatering System (DS) is designed to remove and filter water from the three types of defueling canisters - fuel, knockout, and filter canisters. The water removed from the canisters is transferred to the DWC system for processing through the DWC lon exchanger K-2.

The DS also provides the argon cover gas for canister shipping. The DS is shown schematically in Reference 1.

Page 6 Rev. 2 0196Y

15737-2-M72-DS01 n

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Removal of the water in the defueling canisters will reduce the weight of the canisters to meet shipping requirements.

At least half of the hydrogen / oxygen catalysts in the-canisters will not be submerged; this will ensure that the catalysts remain effective. Argon cover gas, at approximately 2 atmospheres absolute, prevents air or water intrusion. When a canister is submerged, water intrusion may raise the water level in the canister above the catalysts, making them inoperable. When the canister is out of the water, air intrusion increases the pyrophoricity potential of the defueling debris within the canister. For more information on catalysts, pyrophoricity and the use of' argon within the defueling canisters, refer to Reference 13.

High pressure argon from cylinders is supplied through a manifold which regulates the pressure to approximately 45 psig. The argon supply line then branches to provide a source of gas for two dewatering and gas covering trains. A pressure regulator for each train V002A and V0023. (PCV-1A 2

and PCV-1B) is supplied so that dewatering one' canister while covering a second canister may be accomplished simultaneously and independently. An ASNE Section VIII Code relief valve (R-3) prevents the argon supply lines and the defueling canisters from being pressurised above 110 psig. The canisters are ASME Section VIII Code vessels and, therefore, must be protected against overpressurisation as stated in part UG-125 of the Code.

R-3 is provided to meet this requirement. R-1A and R-15, located downstream of V002A and 2

V0028 (PCV-1A and PCV-15), are set to relieve at 55 psig.

This set pressure prevents the possibility of a 60 psi pressure drop across the filter media in a filter canister which could damage the media.

Valves (V004A and V0045) shut off the arson flow to the canisters. The pressure indicators (PI-2A and PI-28) are located upstream of these valves so that the pressure may be adjusted to the correct setting before allowing argon to flow into the canisters. This arrangement is necessary to prevent pressure increments greater than,1 poi from occurring in the filter canisters. Pressure increments less than or equal to 1 psi prevent the differential pressure across the filter media from exceeding 1 psi.

If the differential pressure across the filter media exceeds 1 psi, the filter bubble point may be broken and the filter canister would not be effectively dewatered. The 1 poi differential pressure value is based on;a recommendation by the filter media supplier.

A flow meter for each train (FI-3A and FI-38) indicates when gas flow into the canisters has stopped; this signals the need to increase the pressure to continue dewatering or that the effluent path is blocked.

Page 7 Rev. 2 0196Y

15737-2-M72-DS01 Pressure indicators (PI-12A and PI-12B) are only used to measure the cover gas pressure in the defueling canisters immediately following dewatering and just prior to canister shipping. V016A and V016B are immediately upstream of the indicator takeoffs. V016A or V016B is closed when the canister pressure is checked prior to shipping. This way the argon supply line through tl.e control manifold to V016A or V016B is not pressurized by the canister and effects on canister pressure should be minimized.

Hoses with Hansen quick disconnect couplings connect the argon supply lines and effluent paths to the defueling canisters with the aid of remote handling tools (furnished under the canister task). A jib crane is mounted on the DS platform to handle DS tools and assist in maintenance and repair activities. The jib crane meets ANSI B30.11-1980 and 2

JHI-2 Lifting and Handling Program requirements. Sight flow indicators with internal paddles (FG-5A and FG-5B) are located in the effluent lines. Gas bubbles in a sight flow indicator indicate that the canister is dewatered to the extent possible.

If the internal paddle is motionless, it is an indication that either the canister drain is clogged or that the canister is at an equilibrium state. The argon gas that enters the effluent lines is vented to the DS holdup tank (DS-T-1) via automatic vent valves (V011A and V011B).

The effluent water is filtered through a filter canister (F-1), which has a 0.5 micron nominal rating, and stored in the hold up tank (T-1).

When the system is in the recirculation mode (see Section 3.3.5), the differential pressure across the filter, F-1, for all practical purposes can be read from pressure indicator, PI-4, since the hold up tank, T-1, is under a slight negative pressure (i.e. <12 inches water). When the pressure drop across the filter 2

canister, F-1 reaches 45 pai, the filter canister is fully loaded and must be replaced. The tank is vented to the SDS offgas filter and has an overfill line to the spent fuel pool which prevents water from entering the SDS offgas vent piping. A submerged inlet with an isolation valve (V018) has been provided on the tank to allow the addition of borated pool water into the tank.

Borated pool water may be needed in the tank for the backflushing operation if the amount of water in the tank from dewatering is not sufficient, and for 2

I diluting the effluent in the tank. A bubbler indicates the water level in the tank.

The pumps (P-1A and P-1B) are submersible horizontal centrifugal pumps. Because the pumps are located underwater where maintenance and repair are impractical, two 100%

capacity pumps are provided. The pumps are manually controlled by HIS-9A and HIS-98 with an interlock that trips the pumps on low level in the tank, T-1.

The pumps transfer the water in the hold up tank to the DWC system for processing. The flow is directed to the DWC lon exchanger K-2.

Page 8 Rev. 2 0196Y

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15737-2-M72-DS01 i

The transfer pumps have a recirculation line back to the filter, F-1, with a sample line that runs to DWC Sample Box No. 1.

This provides the ability to further filter the effluent, and the opportunity to sample the effluent before transferring it to the DWC ion exchanger. The concentration of the, effluent from the tank should be below 0.84 2

pCi/cm Cs-137 prior to transferring the effluent to the DWC ion exchanger.

The backflush line provides the ability to reverse the flow l2 of water back into a defueling canister to clear a drain screen that has become clogged (i.e., to backflush). The backflush line is filled from valves V005A and V005B to valve V043 by opening valve V022. Valve V022 is then closed and the line is pressurized with argon by opening the supply line with valve V043 which simultaneously closes the vent line.

2 The argon pressure is controlled by pressure regulator V041 (PCV-10) and measured by pressure indicator PI-14.

The three-way plug valve, V005A or V005B, is positioned so that the appropriate canister is backflushed. The volume of

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backflush water is limited to the amount of water in the pipe from valve V043 to valves V005A and V005B, which is less than 5 gallons. The operating pressure for backflushing is controlled by the operator and maintained below 10 psig. The relief valve, R-2, is set at 10 psig. The filter media in a filter canister can be damaged if the differential pressure during reverse flow exceeds 10 pai. A backflush pressure of less than 10 psi ensures that the AP cannot exceed 10 paid.

The argon supply lines into the canisters have a branch which provides a flow path for gas and water which exits the canister during backflushing. This flow path is opened with the three-way plug valve, V006A or V006B, which also isolates the argon supply line. An automatic vent valve, V008, vents 4

gas from backflushing to the holdup tank, T-1.

Water from backflushing is routed back to the filter, F-1, and into the hold up tank, T-1, for transfer to the DWC system.

Above each canister in the dewatering system canister racks

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is an array of four ion chambers mounted 900 apart. This array is mounted midway between the top of the canister and the surface of the water. After the canister is dewatered, it is raised through the array and the ion chambers provide readings to a data logger for the gamma field detected along the entire length of the canister. These readings will be used to provide a curie estimate for each canister.

I A connection consisting of an isolation valve and a Hansen j

quick disconnect coupling is provided on each effluent line and the vent line to the SDS offgas system. These connections are provided so that the system can be flushed to reduce dose rates in the system. By-pass spool pieces are provided to connect canister inlet and outlet lines without using a canister.

These by-pass spool pieces facilitate flushing, provide a storage location for connection tools, Page 9 Rev. 2 0196Y J

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15737-2-M72-DS01 and enable the last defueling canister to be dewatered directly to the holdup tank. Water which meets Technical Specification requirements shall be used for flushing.

All DS piping is designed in accordance with ANSI B31.1, 1983 Power Piping.

2 The design pressure and temperature of the DS piping is 50 psig at 1000F.

1.3.2 Major System Components F-1 Filter Type: Defueling Canister with Sintered Metal Pleated Filter Mfr/Model: B&W and Pall /

Rating:

.5 micron nominal 2

Code: ASME VIII, Division I, Part UW (lethal)(1983)

P-1A and P-1B Transfer Pumps Type:

Submersible Horizontal Centrifugal (Canned Motor)

Mfr/Model: Lawrence Pump & Engine Co./A1MD Material: Stainless Steel Rating: 60 gpm @ 100' TDH T-1 Holdup Tank (Previously used as SPC-T-3)

Materials: Stainless Steel Dimensions: 54.17" 0.D., 166.55" High Rating: 2735 psig, 3000F Volume:

900 gallons Code: ASME III, Class 2 A-1 Crane Type: Jib Mfr/Model: Air Technical Industries /JC-22020 Rating: 1 Ton Code: ANSI B30.11-1980 1.4 System Performance Characteristics i

The dewatering and covering operations are performed at the following argon supply pressures:

t l

l 1.

Cover gas pressure 12-13 psig l

2.

Dewatering gas pressure A.

Filter canister 3-10 psig @ 1 psi increments B.

Knockout canister 3-10 psig i

C.

Fuel canister 3-10 psig t

l 3.

Argon supply manifold pressure 45 psig 4.

Backflush pressure

<10 psig The transfer pumps operate at 100 feet TDH at 60 gpm l

t Page 10 Rev. 2 0196Y

15737-2-M72-DS01 1.5 System Arrangement The DS platform is located at the northeast end of Spent Puel Pool "A" and the top of the platform is at elevation 331'-3" (See Reference 3).

The platform is designed to support the activities required to handle two defueling canisters during dewatering and gas covering. Instrumentation and controls for the argon supply are located at a DS control area on 347'-6" in the vicinity of the northeast end of Spent Fuel Pool "A".

Instrumentation and controls for pumping operations are located at the west end of the intermediate DS platform at elevation 341'-3" in the northeast end of Spent Fuel Pool "A".

The system equipment is located underwater in this area except for:

1) the argon manifold and supply lines up through valves V016A and V016B, 2) portions of the DWC tie-in, 3) the sight flow indicators (FG-5A and FG-5B), and 4) the majority of valves. The majority of valves are located above the water level but below the DS platform.

All valves below the platform are manually operated by extension stems. Piping that is not underwater and contains radioactive fluid l2 will be shielded to limit dose rates to 2.5 area /hr.

The platform consists of removable sections so that the valves and equipment are accessible for maintenance and repair.

1.6 Instrumentation and Controls 1.6.1 Controls The controls for the argon supply are located on elevation 347'-6" in the vicinity of the northeast end of Spent Fuel Pool "A" at a DS control area.

Instrumentation and controls for pumping operations are located at the westend of the intermediate DS platform at elevation 341'-3" in the northeast end of Spent Fuel Pool "A".

All operations are manual, except for an interlock with the holdup tank level indicating switch, LIS-8, that trips the pumps, P-1A and P-1B.

The argon supply to the dewatering canisters is controlled by the on-off valves, V001A and V001B. The argon pressure to the dewatering canisters is regulated by pressure regulators

'2 V002A and V002B (PCV-1A and PCV-1B), and the flow is l

controlled by valves V004A and V004B. The argon pressure for backflushing is regulated by pressure regulator V041 2

(PCV-10). The argon supply to the backflush line is controlled by the three-way plug valve V043.

The transfer pumps are manually operated by HIS-9A and HIS-9B with an interlock that trips the pumps on low level in the tank, T-1.

The air supply pressure for the holdup tank water level measuring device is regulated by the pressure regulator 2

V017 (PICV-6), and the air flow for the bubbler is regulated by the purge rotameter, FICV-7.

Page 11 Rev. 2 0196Y

15737-2-M72-DS01 1.6.2 Valves All valves are manually operated. Valves below the DS 2

platform are operated by extension stems from the DS platform.

1.6.3 Power 480V, 3 phase starters are located at the DWC motor control center, DWC MCC 2-32C, for the transfer pumps, P-1A and P-1B.

120 VAC power will be available for underwater lights and remote cameras.

1.6.4 Monitoring The argon supply pressure and flow to the dewatering canisters are monitored by pressure indicators, PI-2A and PI-2B, and flow indicators, FI-3A and F1-3B.

The canister pressure, after dewatering and also prior to shipping, is monitored by the pressure indicators PI-12A and PI-12B.

The argon pressure for backflushing is monitored by pressure indicator PI-14.

Pressure regulator V017 (PICV-6) and purge rotameter FICV-7 l2 monitor the pressure and flow of the instrument air for the level indicator (bubbler).

Level indicating switch, LIS-8, displays the water level in the holdup tank.

Pressure indicator PI-4 measures the pressure of the recirculation line.

Flow indicator F1-11 monitors the water flow to the DWC system and water flow during the recirculation mode. Pressure indicator PI-13 measures the pressure in the sample line at the sample box.

l2 l

l The sight glasses (FG-5A and FG-5B) with the use of remote cameras provide indication of gas flow or no flow conditions in the effluent line.

All instruments are located above the water level.

1.6.5 Lights l

Underwater lights are mounted on the DS platform structure to improve visibility.

1.6.6 Trips and Interlocks The DS transfer pumps, P-1A and P-1B, are provided with low level setpoint trips for the holdup tank, T-1, to ensure that the pumps do not run dry.

l The transfer pumps are also equipped with temperature 2

switches that trip the pumps on high temperature.

Page 12 Rev. 2 0196Y

15737-2-M72-DS01 1.7 System Interfaces The DS interfaces with four systems;

1) Submerged Demineralizer System (SDS)

The DS vents excess argon gas through automatic vent valves to the holdup tank (T-1).

The tank is then vented to the SDS offgas filter via a tie-in to the 6" offgas line.

2) Defueling Water Cleanup (DWC) System The DS transfers water from the holdup tank, T-1, to the DWC system for processing. The tie-in is made upstream of the DWC ion exchanger K-2.

The DWC motor control center, DWC MCC 2-32C, supplies 480V, 3 phase power for the DS transfer pumps.

Instrument air is supplied from a DWC Instrument Air Manifold No. 3 outlet for tank water level indication. DWC Sample Box No. 1 is used for the DS sample connection location.

3) The Fuel Handling Building Canister Handling Bridge and Trolley The bridge and trolley locate the defueling canisters which are to be dewatered and covered. The DS platform is designed to provide the necessary clearances to accommodate the canister transfer shield and shield collar.
4) Defueling Canisters The DS and associated platform are designed to accommodate the defueling canisters which are designed by B&W. The DS connections will be operated by long handled tools also designed by B&W. The defueling canisters have a 14 inch nominal 0.D. and 150 inch maximum length. The maximum design wet weight of the canisters is 3355 lbs. The canister shell will be straight to within 0.125 inches per 12 feet.
5) Fuel Handling Building Heating and Ventilation System 2

The relief valves (R-1A, R-1B, R-2, and R-3) on the argon supply lines discharge into a fuel handling building ventilation duct.

2.0 System Limitations, Setpoints and Precautions 2.1 Limitations i

The argon supply pressure to the dewatering canisters shall be limited by..the operators to 1 psi increments when dewatering a filter canister because of filter media properties. The argon cover gas pressure shall be limited by the operators to a maximum 13 psig for all defueling canisters. The argon pressure for backflushing shall be limited by the operator to less than 10 psig.

The transfer pump flow rate is limited to a maximum 30 gpm by DWC flow control valve DWC-V085 (FV-15) when the water is pumped to the DWC ion exchanger K-2.

Page 13 Rev. 2 0196Y

15737-2-M72-DS01 The DS filter canister, F-1, is limited to a 45 psid pressure differential. When the pressure drop accross F-1 approaches this differential, the filter canister is replaced.

2 The weight of a filter canister af ter dewatering must be at least 345 lbs less than before dewatering. A value less than this is an indication that a filter media bubble point break may have occurred.

The filter media must be rewetted (Sect. 3.7.3) and the canister dewatered again.

2.2 Setpoints The pressure safety valve R-3, which is between the argon bottles and the pressure regulators, is set to relieve at 110 psig. The pressure safety valves, R-1A and R-1B, on the argon supply lines to the dewatering canisters are set to relieve at 55 psig.

The pressure safety valve, R-2, on the argon line for backflushing is set to relieve at 10 psig.

The level indicating switch, LIS-8, trips the pumps when the hold up tank water level drops to 24 inches above the bottom of the tank.

The temperature switches, TS-15A and TS-ISB, trip the pumps when the 2

pumps reach 2120F.

2.3 Precautions The DS operators should visually inspect the hose and fittings which are connected to the defueling canisters prior to dewatering.

Because argon is an asphyxiant, the relief valves on the supply lines discharge to the Fuel Handling Building ventilation exhaust; argon used to dewater is vented to the holdup tank (T-1), which in turn is vented to the SDS offgas system.

3.0 Operations 3.1 Initial Fill Borated water from Spent Fuel Pool "A" is introduced into the holdup tank through valve V018. A transfer pump, P-1A or P-1B, circulates the water through all the system piping, except for the argon supply lines, and the piping is vented.

3.2 Startup i

The DS has no unique startup procedures.

3.3 Normal Operations i

3.3.1 Pre-Dewatering Checkout Requirements Page 14 Rev. 2 Ol96Y

f 15737-2-M72-DS01 l'

Prior to the start of dewatering the following requirements must be completed:

1) Recording the weight of the canister,
2) Placing the canister in the support racks, using the canister handling trolley,
3) Connecting the argon supply line and effluent line to the canister, using the dewatering connection tools and DS
crane, 4)

Isolating the recirculation line and the backflush vent / drain line from the supply and effluent lines, and 5)

Isolating the canister train which is not being dewatered from tLe train which is being dewatered.

3.3.2 Canister Dewatering 3.3.2.1 Filter Canister Dewatering Argon is introduced into the filter canister at an initial pressure of 3 psig. The filter canister must have the argon pressure raised in 1 psi increments. When the flow indicator, FI-3A or FI-3B, reads zero flow, valve V004A or V004B is closed and the pressure is raised 1 psi using V002A 2

or V002B (PCV-1A or PCV-1B) and indicator PI-2A or PI-2B.

Valve V004A or V004B is opened and the sequence is repeated when the canister pressure is again equalized (i.e., zero flow reading on FI-3A or FI-3B).

This sequence continues until gas bubbles are visible in the sight glass FG-5A or FG-5B, at approximately 10 psig.

These bubbles indicate the canister is dewatered to the extent possible.

The last defueling canister to be dewatered will be the DS filter canister, DS-F-1.

This canister is moved to a dewatering location and the by pass spool piece for DS-F-1 is connected. The same procedure as above is then used.

3.3.2.2 Knockout and Fuel Canister Dewatering Argon is introduced into the knockout and fuel canisters at an initial pressure of 3 psig.

The argon pressure is then raised, using V002A or V002B 2

(PCV-1A or PCV-1B), until gas bubbles are visible in the sight glass FG-5A or FG-5B, at approximately 10 psig. These bubbles indicate the canister is dewatered to the extent possible. The knockout and fuel canisters do not have restrictions on the rate the pressure is increased during dewatering.

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3.3.3 Canister Gas Covering k

i When the gas bubbles appear in the sight glass, FG-5A or FG-5B, valve V004A or V004B is closed and the drain port (effluent line) is disconnected. The canister is filled with 4'

argon, the cover gas, at a maximum 13 psig.

Covering the canister with argon is complete when the flow indicator FI-3A or F1-38 reads zero.

Valve V004A or V004B is then closed.

The canister pressure can be recorded from pressure indicator PI-12A or PI-12B by opening valve V014A or V014B.

The argon i

supply line is then disconnected.

3.3.4 Post Covering Checkout Requirements The sequence for removing canisters after completing covering operations is as follows:

1) Ensure supply and effluent lines are disconnected,
2) Measure the radiation field values of the canister as the canister is removed,
3) Record the canister weight,
4) Reduce pressure in argon supply line to 1 psig by bleeding argon through valve V006A or V006B, and
5) Close valve V014A or V014B to isolate pressure indicator PI-12A or PI-12B.

l 3.3.5 Transfer to DWC The water from the defueling canisters is stored temporarily in the DS holdup tank. When the tank becomes full, a transfer pump, P-1A or P-1B, is stat.ed with HIS-9A or HIS-9B and the water is recirculated through filter F-1 by opening valve V025 and closing valves V013A and V013B. This operation filters the water in a more efficient manner than occurs during the effluent's first_ pass. The water is sampled through the sample line by opening valves V028, V029 and the appropriate valves in the sample box.

The concentration of the water from the tank should be below 0.84 pCi/cm3 CS-137 prior to transferring the water to 2

DWCS. The water is transferred to the DWC ion exchanger, K-2, by opening valve V030, and closing the recirculation line by closing valve V025.

The sample line is closed by closing valves V028 and V029. When the tank level drops between 24 and 36 inches, the pump is stopped with the appropriate switch, HIS-9A or HIS-9B and valves V013A and V013B are f

opened.

Canisters cannot be dewatered during pump operations because the effluent lines are isolated from the filter, F-1.

The I

canisters can be covered with argon gas during pump operation.

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3.3.6 Canister Pressure Check The DS will be used to check the pressure of a defueling canister previously dewatered and covered. The defueling canister is placed in either of the two canister locations used for dewatering. Valve V016A or V016B is closed, and the appropriate argon supply line is connected. The canister pressure is read from pressure indicator PI-12A or PI-12B by opening valve V014A or V014B. The cover gas reading may vary from the value recorded when the canister was initially covered because of vaporization of water, heating of the cover gas or cooling of the cover gas. The cover gas pressure is adjusted to the original value by adjusting the 2

pressure regulator, V002A or V002B (PCV-1A or PCV-1B), and opening valve V016A or V016B. The argon isolation valve, V016A or V016B, is then closed. The cover gas pressure is monitored by pressure indicator PI-12A or PI-12B for a minimum of ten minutes.

In this time period if the pressure 2

drops more than 0.2 psi and/or bubbles from the canister are visible from the DS platform, the canister will not be shipped. The leak will be located and repaired, and the canister will be repressurized and pressure checked again before shipping. Repair procedures for a leaking canister are not within the scope of this document.

3.4 Shutdown l

The DS is shutdown by:

1) Isolating the argon gas from the supply line, and
2) Stopping the transfer pump (if operating) and closing the DWC and SDS tie-in valves, V030 and V027.

3.5 Draining Draining of the DS is not expected during the life of the system.

However, the majority of the piping between the dewatering canisters 2

and the hold up tank can be drained to the holdup tank. Then the tank can be pumped down. The transfer line and sample lines are provided with low point drains.

3.6 Refilling See Section 3.1, Initial Fill 3.7 Infrequent Operations

+.

3.7.1 Backflushing During dewatering, it may become necessary to unclog a drain screen in either a fuel or knockout canister. The following conditions would indicate the existence of this situation:

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1) A sufficiently high dewatering supply pressure (e.g., 10 to 15 psig),
2) A stationary sight glass paddle, and
3) No gas bubbles visible in the sight glass.

Backflushing is required to clear a blocked canister drain.

2 The backflush vent / drain line is opened for the appropriate train, while the argon supply line for that train is isolated with the three-way plug valve V006A or V006B. The backflush argon supply line is isolated, while the line to vent valve V044 is opened with the three-way plug valve V043. The transfer line and the effluent lines must be isolated by closing valves V030, V013A, and V013B respectively. The backflush line is filled by one of two ways: 1) A transfer pump, P-1A or P-1B, is dead headed against V030 and V025 with V022 open to fill the line back to V044; or 2) A transfer 2

pump, P-1A or P-1B, is started with V025 open so that the system is in the recirculation mode; then V022 is opened to fill the line back to V044.

Valve V022 is then closed and the argon supply pressure is adjusted. The three-way plug valve, V043, is positioned to open the argon line and close the vent line. Transfer pump, P-1A or P-1B is stopped and valve V015 is closed.

The three-way plug valve, V005A or V005B, is positioned to allow the backflush water into the appropriate canister. When backflushing is completed., valve V025 is closed, valves V015, V013A and V013B are opened, and the three-way plug valves V043, V005A, V005B, V006A, and V006B are adjusted to their normal positions as shown on Reference 1.

3.7.2 Canister Pressure Reduction If a defueling canister is inadvertently overpressurized (i.e., P > 13 psig), the' pressure may be reduced by bleeding off argon from the canister, through valve V006A or V006B, and the automatic vent valve, V008, to the holdup tank.

l 3.7.3 Rewetting Filter Media l

If the filter media bubble point is broken, then the filter canister cannot be effectively dewatered and the media must be rewetted. This situation will be detected by weight measurement after the dewatering canister is disconnected l

from the DS and is being raised by the CHB (See Sect. 2.1).

The canister is relocated in a DS rack and a Hansen 1/4 inch 2

tool with a socket is used to flood the canister. A one hour period is allowed to let the water adhere to the filter media r

j before attempting dewatering again.

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15737-2-M72-DS01 3

4.0 Casualty Events and Recovery Procedures 4.1 Casualty Events The following five events will shutdown the DS:

l2

1) A loss of power will render the transfer pumps, underwater lights, and cameras inoperable,
2) A line break disrupts the dewatering flow paths,
3) A loss of instrument air prevents the tank level indicator from
working,
4) Canister handling accidents can damage the canister, tools or portions of the DS, and l2
5) Filter canister filter media rupture will spread fuel fines throughout the system piping.

.l2 4.2 Design Features to Mitigate Effects of Casualty Events The DS mitigates the effects of the events listed in Section 4.1 as follows;

1) Loss of Power -

Adverse conditions would not result, but the system should be shutdown (see Section 3.4).

2) Hose or Line Break -

Armored hose is being used where possible to reduce the possibility of a hose rupture.

This is not a radiological or safety concern because any loss of contaminated water from the DS is insignificant compared with the large volume of borated pool water.

3) Loss of Instrument Air -

Adverse conditions would not result, but the system should be shutdown (see Section 3.4).

4) Canister Handling Accident -

Canister handling accidents, including drops, are addressed in a separate analysis (See Reference 4).

5) Filter Canister Filter Media Rupture -

i The maximum pressure in the system is 55 psig. This is below the operating differential pressure capability of the filter.

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15737-2-M72-DS01 4.3 Recovery Procedures Recovery procedures for the casualty events listed in Section 4.1 are as follows;

1) Loss of Power - The system is shutdown (see Section 3.4), power is restored, and normal operations resume (see Section 3.3).
2) Line or Hose Break - The system is shutdown, the pipe or hose is replaced, and normal operations resume.
3) Loss of Instrument Air - The system is shutdown, the air supply is restored, and normal operations resume.
4) Canister Handling Accident - The system is shutdown, if necessary, the damage is repaired, and normal operations resume.
5) Filter Media Rupture - The filter, F-1, is replaced and the system is run in the recirculation mode (see Section 3.3.5) before normal operations resume.

5.0 Maintenance The maintenance procedures are the recommended practices and intervals as prescribed by instrument and equipment vendors. When the equipment information is available, this section will be expanded.

6.0 Testing 6.1 Hydrostatic Testing All piping and hose will be hydrostatically pressure tested to meet the requirements of ANS1 B31.1 1983 Power Piping.

6.2 Instrument Testing l

All instruments will be calibrated by the field and verified operational after installation.

l 6.3 Periodic Testing i

l No periodic tests are required.

7.0 Human Factors The argon supply hose and effluent hose are different sizes for identification of inlet and outlet canister connections.

Quick disconnects are used for canister connections to facilitate hook-up operations.

I All instruments, valves and equipment have name plates for identifica-tion. Controls and instruments are mounted several feet above the floor or the platform.

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