ML19220B884

Forwards Safety Evaluation Input Re Reactor Vessel Internals & Reactor Coolant Sys

ML19220B884
Person / Time
Site:	Crane
Issue date:	10/08/1975
From:	Maccary R Office of Nuclear Reactor Regulation
To:	Moore V Office of Nuclear Reactor Regulation
References
NUDOCS 7904270587
Download: ML19220B884 (3)

Text

e O-

,, -O w

r -:

d hf,

~

~- -

..n.-

..-..:.._._.n..

5 Yi Docket No.:

30-320 MS 24-12 Voss A. Moore, Assistant Director for Light Kater Reactors, Group 2 Division of Reactor Licensing FE'TROPOLITMi EDISON COF?MiY, THREE MILE ISLAND, U'iIT 2, (OL), DOCKET NUIBER 50-320 Plant Name: Three Mile Island, Unit 2 Suppliers: Babcock and Wilcox; Burns and Roe Docket Number: 50-320 Responsible Branch and Project Manager:

L'4R 2-2; Harley Silver Requested Completion Date: October 10, 1975 Task

Description:

Safety Evaluation Report Review Status: Complete i

The iniormation submitted by the applicant, including A=end=ent 'Io. 32, has been reviewed by the Materials Application Section of the Materials Engineering Branch, Of fice of Nuclear Reactor Reg :lation. Our sections of the Safety Evaluation Report are enclosed.

Origir.f deci by R A 3'.accry R. R. Maccary, Assistant Director for Engineering Division of Technical Reviev Office of Nuclear Reactor Regulation cc w/ enc 1:

D. Eisenhut, W.

R. E. Hafn -an, TR Distribution:

S. Varga, RL

( Decket File 50-320 M. Kehn muyi, TR NRR Rdg.

S. S. Pawlicki, TR MTE3 Rdg.

I. Knial, RL RE l-1 (3 Mi. Is. Unit 2)

U. Potapovs, TR W. S. Hazelton, TR H. Silver, RL V. Goel, TR 7904o70 N1 H. F. Conrad, TR

~

cc /o encl:

W, G. Mcdonald, MIPC R. Boyd, RL

Enclosure:

MTIB SER sections DA

'/

TR:M"4:G, TR:W TR:MT" o,,,e,

evaaa = = e-

,ip.

UPot oIS._. _.1

1. Chi ___ _.. CCary 10/f/75 10/7/75

_10((/15. __

r.

• 10/9 /7s ran. Azc-sis (Ep.9 55) ArcM 0240 W u. s. movan==aser ene=me oblicd s,7psad

METP,0FOLITAN EDIS0" COMPANY THREE MILE ISLAND, C' LIT 2 DOCIET 50-320 (OL)

SAFETY EVALUAIION MATERIALS ENGINEERI'!G BRANCH MATERIALS APPLICATION SECTION REACTOR Reactor Vessel Internals Geheral Materials Considerations We have reviewed the selection of =sterials for the reactor vessel internals required for reactor shutdown and co=ponents relied upon for adec,uate core cooling. All =aterials are co=patible with the reactor coolant and have perfor ad satisfactorily in si=11ar applications.

The use of =aterials proven to be satisfactory by actual service ex-perience will provide reasonable assurance : hat the reactor vessel in-ternals will not be susceptible to failure by corrosion or stress corrosic a cracking.

REACTOR COOLANT SYSTE'4S AND CONNECTED SYSTDIS General Materials Consideratiens We have reviewed the =aterials of construction for the reactor coolant pressure boundary to ensure that the possibility of serious corrosion or stress corrosien is 4 4 d'ed.

All =aterials are compatible widt the expected enviren=ent, as proven by extensive testing and satisfactory service perfor=ance. The applicant has shown that the possibility of intergranular stress corrosion in austenitic stainless steel used for components of the reactor cociant pressure boundary was =inimized be-cause sensitization was avoidcu and adequate precautions were taken to prevent conta=ination during Sauufacture, shipping, storage ard construc-tion.

Sensitization was avoided through appropriate controls on welding processes.

The use of these naterials with satisfac' tory service experience in other reactors and the controls placed on welding procedures provide reasonabla assurance that austenitic stainless steel co=penents will be compatible with the expected service environ =ents and that the possibility of loss of structural integrity is =ini. sed.

Water Chemistn Control Further protection.against corrosion proble=s will be provided by con-trol of the che=ical environ =ent.

The co= position of the. reactor coolant will be controlled and the proposed =axi=u= conta=inant levels as well as h

~

O the pH, hydrogen overpressure and boric acid concentrations, have been shown by tests and service experience to be adequate to protect against corrosion and stress corrosion problens.

The possibility that serious corrosion or stress corrosion problems would occur in the unlikely event that containment spray system opera-tion is required vill be mini =1:ed because the pH c f the recirculating coolant will be =aintained greater than 7.0 by additions of sodium hydroxide.

s The controls on chemical cocposition that will be imposed on the react. r.

coolant provide reasonable assurance that the ranctor coolant boundary materials vill be adcquately protected from conditions that would lead to loss af integrity froc stress corrosion.

Control of Stainless Steel Welding We have reviewed the controls imposed by the applicant to prevent not cracking (=1crofissuring) of austenitic stainless steel welds. The precautions include control of the weld metal composition to ensure adequate delta ferrite cone.ent in the weld =etal.

The welding processes and procedures comply with Section IX of the ASME Code.

The use of =aterials, processes and tesc =ethods that are in co=pliance with the ASME Code require =ents and rece==endations provide reasorable assurance that loss of integrity of austenitic stainless steel velds caused by hot cracking vill not occur.

e e

aJ d /, g)

.