ML19323A052

To Mini Decay Heat Removal Sys Design Criteria

ML19323A052
Person / Time
Site:	Crane
Issue date:	02/26/1980
From:	Dunferd E, Shillman G METROPOLITAN EDISON CO.
To:
Shared Package
ML19323A051	List: ML19323A050 ML19323A052
References
NUDOCS 8004160184
Download: ML19323A052 (15)

Text

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1 T'riREE MILE ISIAND - UNIT No. 2 MINI DECAY HEAT REMOVAL SYSTEM i.

DESIGN CRITERIA i !-

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REVISION DATE PREPARED BY APPROVED BY

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.THREE MILE ISLAND - UNIT NO. 2 MINI DECAY HEAT REMOVAL-SYSTEM i

DESIGN CRITERIA i.

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MINI DECAY HEAT REMOVAL SYSTDI DESIGN CRITERIA 1.0 SCOPE Tnis document establishes the design criteria for a small scale der ay heat removal system to be used to cool the reactor core for three years. The system consists of a pump / heat exchanger subloop to be in-stalled in parallel with the existing decay heat system and in paral-1el with the Westinghouse designed Alt <*rnate Decay Seat Recoval Sys-tem.

The system will be used to remove decay heat from the reactor

_ core until full defueling'has.been. performed.

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2.0 INTRODUCTION

The reactor coolant syste= is currently in a natural circulatien mode with heat being removed through Steam Generator "A" in a steating mode. In order to reduce the vulnerability of the plant cooling mode, a force circulation system with a minimum of supporting systems is e

p re ferrec'.

A small scale decay heat system capable of removing the small amount of decay heat remaining (<_1 MW) in the Unit 2 core will suit this purpose. All system components shall be enclosed in the existing Unit 2 Fuel Handling Building or Auxiliary Building to minimize the poten-tial for release of radioactivity to tihe environment.

3.0 FUNCTIONAL AND DESIGN REQUIRDIENTS 3.1 Perfor ance Requirements 3.1.1 The system shall recirculate reactor coolant through the core for removal of decay heat.

The ultinate heat sink shall be river water vich the Nuclear Eer-vices c1csed cooling loop to transfer heat frc= the reactor coolant to river water.

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Manufacturing Installation Description Code Code Connection to the decay heat ASME -

ANSI system downstream of DH-V3 Section III B31.7 up to and including the Class 2 Class 2 first isolation valve.

Connection to the decay heat ASME -

ANSI system downstream of DH-V3 Section III B31.7 from the first isolation Class 3 Class 2 valve up to and including the second isolation valve Conne: tion to the decay heat ASME -

ANSI syste n ups tream.of DH-V4B s --< --

Section III : - -

831.7

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-f up tc and-including the Class'2 Class ~ 2'-

second isolatien valve Connections to the existing Nuclear Services closed cooling t_

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piping up to isolation valve ANSI B31.l*

ANSI

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isolation valves ASME -

ANSI (T

Section III B31.l*

Class 3 Balance of piping ANSI B31.1 ANSI B31.1-6 Heat Exchangers ASME -

Section VIII TEMA Standard (ASME Section III.if available)

Pumps Hydraulic Institute Standards (ASME Section III if available)

Filter ASME -

bN Section VIII Seismically supported for Category I loadings kv 5

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3.3 Desian Basis 3.3.1 The portionr of the system that are ANSI B31.7 Class 2 shall be seismic Category I.

The remaining portions of the syrtem that convey reactor coolant shall be ds-Pu v 3 signed to operating basis-earthquake (OBE) lo' ads. The balance of the system can be designed as nonseismic.

except the NSCC tie-in lines up to the isolation valves shich shall be category I seismically supported.

2 3.3.2 The system shall be designed to operate with a loss of offsite power.

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3.3.3 The system shall be equipped with test and instru-mentation connections for system pre-operatisnal testing and nor=al operation.

3.3.4 The system shall be designed to supply cooled reactor coolant water to the RCS through the Decay Heat In-jection lines and receive heated coolant through the Decay Eeat return lines.

3.3.5 The system design shall ecploy all velded connections 1

to the greatest extent possible to =inimize system leakage.:. All two inch and larger _ piping. shall be-t- _-- _- --f. f _ _ :

welded except flanges at equipment: connections.- - All '--

connections to the process piping shall be welded or screwed with seal weld up to the roo valve.

2.s e y. 2 3.3.6 The piping system and equipment shall be provided with, adequate vent and drain connections.

3.3.7 The system design shall minimize.the use of auxiliary support syste=s (bearing cooling water, lubrication oil and instrunent air).

Loss of instrument air shall not change the operating parameters (flow and tempera-ture) of the system.

3.3.8 The system shall be designed to remove the required heat load at the temperature of the cooling. vater shown in Section 3.4.

l 3.3.9 The system shall have provisions for.the future in-stallation of a water purification system with the capability (resia disposal and shielding) to handle radioactive water.

Installation and startup of this equip ent shall not interrant system function. ! '

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3.3.10 The system shall be provided with proper overpressure re-

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lief devices.

The discharge of the cverpressure relief devices shall be piped such that they minimize the spread of contaminated fluids ano shall be provided with some Rev 5

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means of visual indication of leakage.

3.3.11 The sys te:shall have proper connec t' cns and oti,er provi-

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sions for flushing of new piping and co :ponents prior to startup.

I'eu piping and cc.m;,onents shall be in a clean 3

s and r.eutralized state uhen installed.

Chemical cleaning J."

shall not be i: sed af ter installation.

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drainage-such as' pump seal *3eak of f s; flanges, and valve stees.

Consideration shall be ;iven to containing both gasecus and Jiquid ef flaants, and safely deliver'.ng the vastes to GPU approved processing systees.

O 3.3.13 A recirculation line to meet the startup flow recuirecents Rev. 2 of the pumps shall be provided.

f system recirculation line is ' acceptable forthisservice.lRev. 3, 3.3.14 Tne sys tem shall be designed for J ong-t'erm continuour coal-

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ing for a minimum of three years.

3. 3.-15. For increased system availability considerations, the sys-1 tem shall have redundant heat exchangers and pur:ps.

3.3.16 Tae sys tem shall be designed to be isolated from the exist-ing plant sa fe ty sys tems.

Tne system, when in the isolated mode, shall not jeopardize the operability 'or pressure in-

-tegrity of the existing plant safe ty systees.

Tne isola-cion from the Decay Heat Reme, val Sys t ee shall-be wi th den 3 e iso 2ation valves...

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3.3.17 The system shall have provisions for remote isolation, draining, and

,,. 4 flushing to minimize radiation exposure to maintenance personnel

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3.3.18

.The MDHRS dasign shall include a temporary filter which will bs located in the supply line to the MDHRS. This temporary filter.

shall be a "one shot" device intended to be used in the first Rev.

7 minutes of system operation to trap hard particulate which may be contained in the DH drop line. The filter may be used for I

longer time periods as its pressure differential may permit.

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3.4 Sizing Raouirc.nents 3.4.1 The system shall be designed to meet the following requirements:

(a) Flow through reactor core 120 to 175 gpm (b) System inlet temperature 180* F (c) System outlet temperature 130* F (d) Design Pressure ks.J Coolers and pump suction 235 psig g

Pump and discharge piping 235 psig Rev. 2 (e) NSCC water temperature -.

100* F.

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(f) 'NSCC water flowJrate.:._

200 gpm -_

(g) Beat Exchanger duty See Curve 1 3.5 Layout Reauirements

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3.5.1 The system equipcent shall be located to facilitate construction and future modifications and ease of access during operation.

3.5.2 The system flow path shall consist of cooled reactor 4

coolant entering the Decay Heat Removal System up-stream of valve DE-V4B, flowing through the reactor core and returning back to the heat exchanger through the Decay Heat Removal drop line and the new system connection downstream of DE-V3.

On the cooling water' side, the Nuclear Services closed cooling system shall be connected to the shell side of the new Mini Decay Heat Exchanger (refer to Figure 1, attached).

3.5.3 The ultimate heat sink _ shall be provided by the Nuclear Services River Water System.

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3.3.4 Radiation shielding shall be provided between the

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pumps and other equipment and piping to minimize the radiation exposure to maintenance personnel while working on either of the pumps.

This shall-include shielding between the two pumps.

Radiation Shielding and reach rods shall be provided to minimize the exposure to operating personnel when Rev. 2

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3.6.1 All equipm2nt shall t.e located ii: side ths Fuel F3ndiir g Suilding and Auxiliary Suilding.

3.6.2 Eonsideration shall be given to the integrated radia-tion exposure to all sensitive materials (electrical equipment, elastomers, etc.) over the design life of the system..lf equipment cannot be satisfactorily shielded, the materials shall be compatible with expected expo-sure.

3. 6. 3 ' If area radiation levels at the pt.mps are expected to inhibit routine maintenance operations on the pumps, considera tion'shall 'be' give.n'-to providenremoterbearing"-'- "" ~--

lubrication to the pumps and motors.

3.7 Samali,nc Recuirements Ccnnections shall be provided for future sampling lines.

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3.8 Materials Recuirements All wetted mat rials shall be compatible with fluids having water chemistry specified in Section 3.12.

It is expected that austar.itic stainless steel type 304 or 316 shall be used.

l gex. 2 3.9 Electrical Recuirements

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3.9.1 Electrical equipment shall be capable of being started F < --

and powered from an on site lE diesel generator set in the event of a loss of off site power. Loads shall be sequenced on to the diesel generator set manually.

3.9.2 Electrical classification of the system is non-lE, however the electrical power to the operators on the system isola-Rev. 5

, tion valves and the pump motors shall be class 1E. The instru.entation shall be powered from one class lE bus.

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1 3.9.3 Motor rated starting voltage shall be verified and consistent with the voltage regulation capability for the diesel generator to be used. Motor feeders shall be protected consistent with the original plant design und the normal trips for overload, etc.,

shall be used.

3.9.4 Electrical load list: will be provided in the system description.

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3.9.5 " Criteria for General Modification to the BOP Electri-cal System" are applicable. Also, refer to " Criteria

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for Loss of Offsite 80P Electrical Pcteer?.

3.9.6-The, power. supp]y to._the. pump.potors' shall-be2 supplied -

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from separate: 1E bu's'es.

3.9.7' The Mini Decay Heat Removal pump motor power supplys are I

to be interrupted sehen the i.nstallec decay hast re.:v-

sv. 5 al pumps are started.

This' provision shall not inhi-(

bit the operation of the decay heat pumps.

3.10 Testino Reauirements Provisions shall be made fo'r pre ~ opera tional testing of the sys-tem, including hydrostatic tests, flushing of new piping, and demonstration of required pumping capability.

3.11 Ins trumenta tion and Control Recuirements

. 3.11.1 The system shall be designed to provide instrumentation to monitor functional performance requirements, includ-ing but not limited to:

. '(a)

Pump discharge pressure 0-300 psig '

(b)

Hsat Eschanger inlet'ard outlet 50-2500 F l

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(c) Flow Rate Nominally 120 gpm Maximum 200 gpm (d)

N.S.C.C. inlet and outlet Tempera ture 50-1500 F (e) Pump Suction Pressure 0-200 psig R ev. 7.

3.11.2 Control circuits for existing egipment shall be re-viewed to ensure that no spurious automatic, or interlock-sign,a]s-wi41 -cause--incorrect-operation-W-,-.,,

of the system.,

3 11 3 Provisions shall be cade for installation of controls and re=ote indicators in the Unit 2 Control Roc =.

Controls and indicators shall be located in the new control Rev. 7 panel provided.

3.11.4 Control shall be manual. The pbmp control switch shall have start, normal, stop and spring return to P.av. 3 normal positions.

Run/off indicator lights shall be provided for motors and open/close lights shall Le provided for the system isolation valves. (Both lights shall be on when valves are in intermediate posi tion).

3.11.5 Control cables should have 50%, and preferably 100%,

spare conductors to allow for fut$re nodifications.

' 3.11.6 1.oss of system flow shall be alarmed locally and in the ain control room.

3.11.7 (Deleted) g 29, 4 11-

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1 3.11.8 The isolation valve (s) on the NSCC system shall

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automatically close on detection of a leak, i.e.,

imbalance in the flow to and from the Mini Decay Heat Removal cooler.

3.11.9 Area radiation monitors shall be provided and shall alarm on the local control panel and in the l

Control Roem.

3.12 k'a ter chemistry --...-

pH 7.5 - 9.5 (nominal 8.5)

Eeren 3000

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Eydrogen 5-40 cc/Kg (nominal 15-40 cc/Kg)

Re v. 2 Chloride

<4 ppm Fluoride

<1 ppm Dissolved Oxygen

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