ML17275A529

Comments on NUREG-0577,in Response to NRC 800520 Ltr.Basis for Required Margins Above Nil Ductility Transition Temp Should Be Provided.Definition of Operating Temp & Scope Needed

ML17275A529
Person / Time
Site:	Columbia, Washington Public Power Supply System, Satsop
Issue date:	08/06/1980
From:	Renberger D WASHINGTON PUBLIC POWER SUPPLY SYSTEM
To:	Snaider R Office of Nuclear Reactor Regulation
References
REF-GTECI-A-12, REF-GTECI-ES, RTR-NUREG-0577, RTR-NUREG-577, TASK-A-12, TASK-OR EMN-DB-80-30, NUDOCS 8008120482
Download: ML17275A529 (6)

Text

R EGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)ACCESSION NBR:8008120482 DOC~DATE: 80/08/06 NOTARIZED:

NO PLACKET¹FACIL:50-397 NPPSS Nuclear Pr o J acti Unit 2i Wash jngton Public Powe'55000397 50-460 14PPSS Nuclear Project<Unit 1<Nashington Public Powe 09000460 STN-50-508 NPPSS Nuclear Project~Unit 3+Hashjngton Public 05000508 STN-50-509)IPPSS Nuclear Projecti Unit 5~Washington Public 05000509 50-51.3 INPPSS Nuclear Project~Unit 4i'Aashington Public Powe 05000513 AUTH'AME AUTHOR AFFILIATION RENBERGERpO.L.

Nashfngton Public Power Supply System REC,IP.NAME REC IP IENT AFFILIATION SNAIDERiR.P.

Systematic Evaluation Program Branch

SUBJECT:

Comments.on NUREG-0577~in response to,NRC 8005?O.ltr.Basis for reauired margins above".nil ductility transition temp should be provided.Definition of operating temp 8 scope needed.DISTRIBUTION CODE: A018S COPIES RECEIVED:LTR ENCL SIZE: TITLE: Component Support Fracture Toughness (USI A-12)t'OTES:PM:

2 cooies of,all material.05000397 Standardjzed Plant.05000508 Standardized Plant.05000509 RECIPIENT IO CODE/NAME ACTION: YOUNGBLOODgB COPIES RECIPIENT LTTR ENCLID CODE'/NAME 7 7,'OPIES LTTR ENCL'NTERNAL:

A/0 MATL 8 QUAL I8E 10 NRC POR 02 OR ASSESS 46 1 1 2 2 1 1 1 1 GEN ISSUES BR14>>MATL ENG 45, OP EVAL'R REG FI 01 1,1 1 1 1 1 1.1 EXTERNAL: ACRS NSIC 30'6 16 04 1 1 LPOR 03 1 1 40'$gaga p4, TOTAL NUMBER OF COPIES REQUIRED!LTTR M ENCL 2~

Washington Public Power Supply System A JOINT OPERATING AGENCY P.O.BOX 9ea 3000 GEO, WASHINCTON WAY RICHLAND, WASHINGTON 99352 PHONE (509)375.5000 August 6, 1980 EMN-DB-80-30 Mr.Richard P.Snaider Generic Issues Branch Nuclear Regulatory Commission Washington, D.C.20555

Subject:

Comments On NUREG-0577 And Related Letter from Darrell G.Eisenhut.Dated Ma 20, 1980 The Supply System comments on the subject NUREG and related letter are provided in the attachment.

Very truly yours, DLR:DB:bt Attachment

.L Renber e Assistant re tor Technology j)0/8 5/Ji 6008120 482 kt ATTACHMENT

GENERAL COMMENT

S 1.Fracture Safe Criteria (i)'The basi s for the requi red margins above the nil ductility transition temperature (NDT)should be provided.The margins do not appear to be based upon the crack arrest approach developed by Pellini et al.(ii)The criteria allow only for two approaches--satisfy the NDT margin or assume member fai lure.There should be some inter-mediate position allowed, using linear elastic or elastic plastic fracture mechanics in combination with NDE to demon-strate fracture safe design.Nithout knowing the basis for the fracture toughness criteria provided in the NUREG it is diffi cult to make more specific comments.(iii)Following from (i)to (ii)it is apparent that following the NUREG approach no credit can be taken for factors such as volumetric inspection or post weld heat treatment.

The criteria would be the same irrespective of inspection method or heat treatment.(iv)Consideration should be given to providing different fracture'afe criteria for normal, upset and accident conditions.

Normal stresses are low and the probability of accident conditions is also very low.2.Definition Of Operating Temperature The selection-of 75 F seems arbitrary.

Normal operating temperatures are usually higher but minimum design temperatures lower.Again consideration should be given to having different criteria for shut down, start up and operation.

3.Definition Of Scope More guidance should be provided to define the type and extent of the supports covered by this NUREG.Also, interfaces with equipment and buildings should be defined.For example, on our WNP-2 plant the recirculation pump is suspended by hangers via the piping.The recirculation motor is hung by hanger rods from a cylindrical steel structure between the pump and the motor.It is difficult to define whi ch of these items fall within the scope of the NUREG.4.Basis For Assumed Upper Bound NDT Values The upper bound values provided for the high strength low alloy steels may not be conservative.

These steels seem particularly susceptible to variations in rolling practice.l Attachment Page 25.Implementation Part II of the NUREG, the report by Sandia Labs, seems to fit the scope of a NUREG document.It would be preferable if the implementa-tion sections were presented as an implementation letter, Regulatory Guide or Branch Technical Position.6.Lamellar Tearing It is apparent that adequate methods of predicting the occurrence of lamellar tearing do not exist: Emphasis should be placed on upgrading the base material quality requirements of the ASTM/ASME material specifications to provide structural materials for critical applications which have: (i)Good through thickness ductility, low residual elements and controlled inclusion levels (ii)Freedom from significant laminar defects (ii i)Freedom from other significant rolling defects (iv)Adequate consistent toughness properties (v)Good weldability It is evident that the present specifications do not provide material which meets these requirements and that the nuclear industry must take the lead in this area rather than depending on the steelmakers.

7.Fracture Toughness Data Base The Sandia report is a commendable attempt to assemble such a data base.Additional data is, however, required and could be obtained from the steelmakers and from impact test data generated for materials whi ch have been used in nuclear construction.

It is recognized that such data may be biased if toughness was specified, however, it would'e very useful for future design purposes.In addition, fut ther characterization of the toughness of weld zones is required for the various processes, consumables and.procedures of interest.This will be particularly important if design against fracture initiation is to be used.It is unwise to assume that the toughness of deposited weld metal can be deduced from the specified toughness for the consumable.

Also, the effect of plate thickness and rolling practi ce on toughness of carbon and low alloy steels should be examined.

Attachment Page 3 8.Non-Destructive Examination (NDE)NDE is an important element for fracture safe design.Specific volumetric examination procedures and acceptance criteria are required for structural steel applications.

Most work has been related to pressure vessels and piping.This should be expanded to include structures.

The acceptance criteria in the structural welding codes are directed more at process and quality control rather than fracture safe design.9.Post Weld Heat Treatment Again this is an important element in fracture safe design and should be integrated into any set of requirements intended to ensure structural integrity.