ML20033H032

Discusses RES Reorganization & Important Activities Since June Meeting,In Response to 880811 ltr.TMI-2 VIP Metallurgical Program Description Encl

ML20033H032
Person / Time
Site:	Crane
Issue date:	12/20/1988
From:	Beckjord E NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES)
To:	Todreas N MASSACHUSETTS INSTITUTE OF TECHNOLOGY, CAMBRIDGE
References
NACNSRRC, NUDOCS 9004160206
Download: ML20033H032 (29)

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UNITED $TATES V-8 NUCLEAR REGULATORY COMMISSION j

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December 20, 1988

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~ Professor Nei1^ E. Todreas j

Massachusetts Institute of Technology.

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Nuclear Engineering Department i

l-Building 24-108

77. Massachusetts Avenue

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Cambridge, MA 02139

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Dear Professor Todreas:

j I am replying to your letter dated August 11 198 that is the.first report of the Nuclear Safety Research Review Comitfee (8N$RRC).

I have taken time j

1 since then to reply because'I wanted to reflect carefully on some of.the issues raised, and because-I wanted to coment on actions.that are essentially 3

complete now, but were not so-earlier.

Also, I am giving a report to the-y

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i Advisory Comittee on Reactor Safeguards at this time on;some issues that are of common interest, y

I write first about the RES reorganization, then about important actions since the June meeting of NSRRC. and then I address the-issues in your letter in 1

order of appearance. My intent is to provide pertinent;information on.these issues to the Comittee.

You may wish to pursue some or all of them in more

. detail at future meetings.

I suggest that we discuss them and the priority of interest when we plan the agenda for the next full meeting.

Reorganization Since the full Comittee meeting in June, I' announced the reorganization of.

the Office that became effective on July.17.

There were four objectives, as follows:

evaluation, nd

-to consolidate and bring into sharp focus the analysis,s Severe. Accident 1.

decision making related to implementing the Comission Policy and the resolution.of Generic Safety Issues; 2.

to restructure severe accident research so as to provide earlier input to decision on severe accident issues as well as to the longer term confirmatory research needed for closure; 3.

to make the most effective use possible of RES resources; and 4.

to clarify the responsibilities of the RES Deputies.

In order to achieve these objectives, I established the Division of Safety Issue Resolution (DSIR), headed by Dr. Wayne Houstor., to carry out the scope of work associated with objective 1.

This Division has three Branches: the 9004160206 B01220 g

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i Professor Neil E. Todreas 2

December 20,1928 Engineering Issues Branch, headed by Mr. Robert Baer; Reactor and Plant Safety Issues Branch, headed by Mr. Karl Kniel; and the Severe Accident Issues Branch, headed by Mr. William Beckner. DSIR is responsible for the analysis of generic and unresolved safety issues, for development and evaluation of proposed new requirements, and for recomending the preferred course of regulatory action based upon appropriate analysis. DSIR also defines the need for short term and confirmatory research associated with these

issues, in this sense some of the user needs for research originate within RES.

For the scope of work associated with objective 2, I established the Division of Systems Research (DSR), headed by Dr. Brian Sheron. This Division has four Branches: the Accident Evaluation Branch, headed by Dr. Nick Costanzi; the Probabilistic Risk Analysis Branch, headed by Mr. Mark Cunningham; and the Reactor and Plant Systems Branch, headed by Mr. Louis shotkin; and the Human Factors Branch, headed by Dr. Frank Coffman, Jr.

As is evident from the branch structure this Division is responsible for systems technology, including thermal hyPaulics, risk and reliability, and human factors as well ds the severe accident research. DSR is then responsible for developing and implementing the research plan for the needs posed by DSIR as well as by other Dffices. The research plans that stem from tie interaction between the Divisions typically go around the communications loop one or more times in order to sharpen and to shorten and economize the key questions that the research should answer,lity for defining within its the research program. DSR also has the responsibi scope the needs for exploratory research.

The Division of Engineering (DE), headed by Mr. Guy Arlotto, relinquished the Engineering Issues Branch to DSIR, but was not affected otherwise in the reorganization. DE has a responsibility for development of research programs with DSIR and other Dffices, that is analogous to the relationships defined in the paragraph above for DSR.

s The organization and responsibilities of the Division of Regulatory Application, headed by Dr. Bill Morris, were not affected in the July reorganization.

In my opinion the reorganization is now accomplishing the objectives of

sharpening the focus of the activities related to decision making on severe accidents, and of restructuring severe accident research, Generic issue resolution has made excellent progress in 1988, but such progress was underway before the reorganization.

Hence it may be premature to judge on the objective of making the most effective use of RES resource, though I think this will be the case.

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' Professor Neil E. Todreas 3

December 20, 1988 Important Activities Since the June Meeting l

At the June meeting I gave you copies of the Integration Plan for Closure of SevereAccidentIssues(SECY-88-147). The Comission has concurred with the plan, and we are moving to carry it out. The Plan includes six primary elements, i

and the Office of Research has the lead role in four of the six, a joint role in i

one, and a role of assistance in one.

Lead (with NRR Support)

Joint (withNRR) l Individual Plant Examination Accident Management Containment Performance Improvement Severe Accident Research Assistance (to NRR and AEOD)

ExternalEvents(earthquake, fire,& flood)

Improved Plant Operations TheIndividualPlantExaminationprogram(IPE)isasearchforsevereaccident vulnerabilities at each lant. The program has been approved by the Comission andwillgetunderwayfolowingworkshopswithlicenseestocommunicatethegoals and objectives of the program as described in the generic letter on this subject sent to all licensees, and to obtain licensee feedback on the process in February.

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The first plants considered in the generic Containment Performance program are the G.E. MARK I containments, and RES will present the analysis, evaluation, and recommendations to the Commission for consideration in January, 1989.

Several generic improvements will be proposed, and follow up research on the question of dry well liner integrity.

A technical review of the Severe Accident Research program has been underway.

since October with the help of a panel of experts from industry, Laboratories.

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and universities taking part in the review.

I note that this panel is considering the risk significance of the various srogram elements, as i

indicated in plant PRA studies, in its thinking a>out the important severe accident research tasks to be done.

I expect to receive the first draft of the evaluation in January, and I believe this will strongly influence reorientation of the program to serve the needs for information both in the short range for issue resolution, and in the long range for confirmatory research. We have just met with the Subcommittee on Severe Accidents, and reviewed with them the Accident Management Program and parts of severe accident research. We also discussed the technical review of severe accident research that is underway.

I propose to discuss the finished technical review, and I look forward to NSRRC's advice on this subject.

RES has developed with NRR an Accident Management program that addresses both near term actions proposed at operating plants and related research needs.

RES intends to prepare a paper for the Commission that, on approval, would be issued as a generic letter requiring licensee actions that will be coordinated with findings of the IPE at each plant, and result in enhanced capability to deal with and recover from severe accidents.

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' Professor Neil E. Todreas 4

December 20,1988 RES has also held NSRRC Subcomittee reviews on the High and Low Level Waste Research programs, on Aging and some of the Materials Research program, and on the Human Factors Research program.

I will turn now to the issues mentioned in your letter, under the main headings of the letter.

General Conclusions a.

Recruiting Managers with Research Experience We discussed in June the failure to recruit an experienced research manager from outside of NRC. On the other hand, two exserienced researchers have come for term assignments at RES: Professor Rudolpi Sher of Stanford, whose assignment is complete in December; and Dr. Khatib-Rahbar of Brookhaven, now midway in a one-year assignment. Both men have been important additions to the staff and have contributed very effectively to research planning and implementation in the severe accident research area.

I bE>1ieve these assignments are analogous to the term appointments made at NSF, and I intend to continue similar assignments throughout RES programs in the future. The assignments are advantageous on both sides: to the research person in gaining a knowledge in depth of RES activities in the field of interest to them; and to RES both for access to research skills and for the flexibility to bring in a number of researchers in several different fields over a period of several years.

As management vacancies become available, RES is considering people outside of NRC as a means of enhancing staff capabilities.

I do think the suggestion to look into NSF methods is a good one, and I will pursue it, b.

University Interaction As noted in your letter the Comittee has not yet reviewed this topic.

Nevertheless I want to coment on i+,

RES plans to increase university interaction by several means, including fellowships during a term or longer period of leave, awards by means of Broad Agency Announcements (BAA), contracts, consulting, and grants.

As noted above, Professor Sher has worked with RES on severe accident resrarch for nearly nine months and has completed his assignment.

Professor Nathan Siu of the Nuclear Engineering Department of M.I.T. spent the sumer of 1987 working on external event PRA studies. Both these assignments have worked well.

I propose to increase direct university participation in research through the BAA and contract approach. We have let several of these this past year, but the start was slower than I would have liked to see, because of the 20%

FY 1989 Budget cut in January.

In effect this cut impaired the ability to make new starts.

I intend to develop university involvement in major research i

Professor Neil E. Todreas 5

December 20, 1988 projects through the means of a BAA effort in parallel with a national laboratory program, in a complementary relationship.

In this way RES could make the best of national laboratory strengths in facilities and in the ability to assemble projects with the innovation and research rigor that I expect from universities.

For two years RES has awarded the maximum allowable total of grants, at li of the RES extramural budget. This is a gratifying result.

I note for your information that RES spent a total of $2.5M at universities in FY 1988.

If the FY 1989 budget stands as is, the amount will be greater this year, c.

Fair and Competitive Contracting of Research The Comittee has not reviewed this topic as yet.

RES is undertaking to increase the participation of research contractors outside of the national laboratories.

I encourage the Division Directors to do so, and have established a FY 1989 target of $16.6M, compared to $12.9M performance in FY 1989, for the university and commercial contract sectors. RES is also giving training to project managers in cost estimation and project management skills in order to improve the capability to award and manage such contracts.

I note that the Waste Management Branch has over a number of years developed a strong university and comercial contractor program.

Program Philosophy a.

Nuclear Regulatory Research Philosophy Your letter comments on the confusion arising from a revised statement of philosophy in the draft Five Year Plan that I sent out. The official statement of philosophy was approved by the Comission and transmitted to the National Research Council under the Chairman's signature in his April 6, 1988 letter.

I have taken steps to discourage the process of editing that resulted in the changes in the Five Year Plan draft, because the original represented a 4

consensus view of the program Office Directors that the EDO recomended to the Comission. The Comission staff has made the suggestion to add a third main 4

purpose for research, relating to preparation of standards. The reason f,or this change is to underline the Comission support for retaining the responsibility for standards work in the Office of Research. You may recall that the National Research Council Report had recomended establishing a separate Office of Standards Development.

I have no problem with adding this third purpose.

i b.

Realism versus Conservatism An underlying purpose of research has always been to improve the understanding of physical phenomena, and it is entirely consistent to say that the basic goal of research in nuclear safety should be to provide quantitative results in terms of a best estimate and a determination of uncertainty. When the results of research are applied to regulatory questions, it is necessary also to establish what margin of safety is required. The NRC has in the past i

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1 Professor Neil E. Todreas 6

December 20, 1988 used and continues to use conservative or bounding calculations in deciding on required safety margins in addition to best-estimate methods. The bounding method can be important in situations in which there is large uncertainty and in situations in which sucn a calculation shows a potential problem to be a non-problem. The ECCS Rule revision signals endorsement of the best-estimate approach for regulation in the case of LOCA thermal-hydraulics, where it became possible to establish uncertainties and safety margins in a generic The ECCS Rule revision represents a culmination of research over sense.

a 20-year period, and an expenditure of more than $1 billion by all parties involved.

Clearly the decisions taken 20 years ago involved large uncertainties, and because of that fact it was necessary then to rely on more conservative calculations.

c.

Safety Goal t

I wrote the first draft of the philosophy statement, and it included reference to the Commission's Safety Goals.

I was not able to achieve a consensus with the other Program Office Directors on this point, and the i

reference to Safety Goals was deleted at that time.

RES, and specifically l

DSIR, has been working on the complex issue of how to incorporate and implement Safety Goals in the regulatory framework since then.

RES will soon send a paper on the subject to the Commission for approval. When the Safety Goal implementation is approved by the Commission, I plan to include its essence in the philosophy statement at the next revision.

I note that the Commission's Safety Goal Policy statement goes directly to the matter of regulatory decisionmaking on issues associated with regulatory requirements and particularly to the role that probabilistic risk analysis can play in this process. PRA is already an important part of the research program in several respects: (1)PRAmethodsarethebasisfortheIPEdescribedabove; (2) RES is working on the development'of improved PRA methods, discussed in the paragraph below on NUREG-1150; (3) RES is undertaking to develop a quantitative determination of the risk associated with human error in plant operations--success in this undertaking would enable the NRC to make judgments about risks contributed by human factors; and (4) RES is using existing PRA methods and results for purposes of research prioritization and planning.,

d.

Research Program Guidance / Accountability I understand your concern that the philosophy statement is not adequate by itself to guide the research effort.

Rather it addresses the question of I

what research to do and when it is enough. As to research management, the basic tools, in successively greater detail, are the Five Year Plan (broad objectives), the program plan, and the research contract (or in the case of nationallaboratoriesForm189)thathasaFIN(FinancialIdentificationNumber).

Project Managers are responsible to their Chiefs and Division Directors for managing the research in technical and financial terms, and achieving the results. The Research Project Management Information System (RPMIS) is the management information tool for this purpose.

In addition each SES supervisor, I

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Professor Neil E. Todreas 7

December 20, 1988 i

i that is myself, the responsible Deputy, Division and Division Deputy Director, and Branch Chief, work in accordance with a July 1 to June 30 yearly contract.

l This contract refers to the Division Operating Plan, and expected results during i

the year. The supervisor in the management structure rates each SES employee reporting to him or her with respect to accomplishments, finally, I rank the SES employees in RES on the basis of their performance to make recommendations for SES bonuses, in the last step I attempt to give important weight to flexibility and creativity in effective achievement of goals.

In summary, I l

think that the process is in place (if anything, it is somewhat cumbersome and duplicative). The question is: is it carried out effectively?

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Research Program Closure r

Your point about the accomplishments necessary for closure of each program element is on the mark. Looking back I can see now that more effort put into defining necessary accomplishments would have paid off in the past in terms of freeing resources to do more urgent work.

I think it is not so much a question of defining accomplishments that are necessary once and for all time at the beginning of a program, because research is a learning process, as it is establishing a state of mind to review need and progress every year, so that management is actively looking for the points of diminishing return and the sufficiency of knowledge, even as it prepares the next five Year Plan.

I think this is a step that RES should introduce into the prioritization process that will be discussed-below, i

Meetina User Needs l

a.

Yearly User Office Letter I like your suggestion that each Program Office Director should write a

. yearly letter stating their satisfaction (or otherwise) with the regulatory research products from RES, and I will undertake to do this, b.

Annual Project Evaluation Without question there are more needs than there are resources withiYrthe RES arograms. Since I came 21/4 years ago, RES has faced annual budget cuts and ins prepared an altered research budget at least six times in response to requests for revisions.

In each case I have determined priorities on the basis of judgments on the part of myself, the Deputies, and the Division Directors and Branch Chiefs. RES has recently completed a prioritization of the FY 1988-1992 Five Year Plan, that I intend to update annually.

In future budget decisions I intend to use this document, as updated, as a decision making tool to sharpen RES budget determinations.

I agree with the Committee's exhortation that the priority setting system should not be too elaborate, rigid, or time consuming to use.

In the final analysis, management judgment, that takes into account all relevant factors, will always be the key factor in decision making on the budget.

I suggest that we review the prioritization report and the process at our next meeting.

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f December 20, 1988 Professor Neil E. Todreas 8

The research prioritiration methodology is based on the value of the results of research.

Projects with higher value receive higher priority. The measures of value in this process are four attributes:

1.

Safety assurance - how effective the research can be in ensuring the NRC safety mission 2.

Usefulness - will research results be useful and timely for decisionmaking 3.

Appropriateness - is it.aopropriate for NRC as opposed to other parties to do the researci 4.

Resources - sunk costs, current year cost, and cost to completion.

A panel of evaluators assessed the value of each research activity with respects to these attributes. The panel consisted of two people with general knowledge of the NRC mission and of the research area, and the Division Director responsible for the research area. The panels began by developing a list of questions that must be answered in each of the five principal areas of the research budget for NRC to carry out its mission.

The Five Year Plan provided the basis for developing these questions.

Four panels performed the evaluation of research at the research activity level (44 research activities intotal).

As part of the assessment, the research activities were also classified as follows:

A.

Basic Activities: -These are long term (5-10 years) basic or exploratory activities that aim to expand the knowledge of nuclear safety, and to maintain the competence of the' Agency.

B.

principal Activities: These activities support the resolution of principal safety concerns and regulatory actions, are mission oriented, and usually of short duration (1-3 years).

C.

Reculatory Activities: These research activities serve to fulfill the f unctions of the Agency, addressing specific safety concerns, and providing independent expertise and information for making timely regulatory judgments.

The' purpose of this classification is to show the distribution of research activities between near term support of Agency functions, near term resolution of safety issues, and long term basic or exploratory research, research to expand the knowledge of nuclear safety and to maintain the kinds of expertise needed to deal with unanticipated problems or events.

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Professor Neil E. Todreas 9

December 20, 1988 i

In my brief status of the prioritization methodology I do not mean to suggest that the subject is not worthy of more detailed discussion.

Rather, !

do suggest that we should review prioritization in some detail at our next meeting.

Long Range Research The prioritization study discussed above classifies research in several ways. One of these is in terms of research activity: basic, principal (support of safety issue resolution), and regulatory. Although I cannot deny that some work in the " basic" activity is work that may take a long time to complete. I believe that the basic activity corresponds reasonably well to the term long range research. Basic activity accounts for approximately 25%

of the research budget.

I intend to maintain basic activity at approximately this level, even during a budget cut.

Specific Programs f

a.

NUREG-1150 You have noted the peer reviews on NUREG-1150, and have urged RES to devote the attention necessary to ensure that the first version will be effective in its intended application. The project has almost completed an l

extensive revision of the report: the purpose of the revision is to respond to the comments of the Kastenberg Peer Review Committee; the LeSage ANS Special l

Comittee on NUREG-1150; the Kouts Panel on the Uncertainty Methodology; reviews by EPRI and other organizations and individuals in the U.S.; and finally with international bodies such as the IAEA in a meeting on NURCO-1150 held in Rome in April, 1988. The revision will go to press in February, 1989.

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I expect that NRC will convene a peer review panel to review the revision.

RES will also hold public workshops and receive further comment.

If as a result of these reviews additional work appears advisable. I expect that we will prepare an addendum to the final NUREG-1150.

The scope of the revision is extensive.

It includes the following:.a reanalysis of the PRA front end; a reanalysis of the containment event trees, with major attention to improvement of the elicitation of expert opinion and l

making the trains of thought more readily traceable; and revision of the source term section. The LeSage ANS Special Connittee has met and reviewed the work on revision before completion, and has advised RES that it is

" cautiously optimistic regarding the final report.

b.

TMI-2 Your letter urges RES to expand the knowledge base through sampling and analysis of the core and reactor vessel. With regard to the reactor vessel, the program to obtain samples for analysis from the bottom head is well underway, under joint sponsorship by NRC and the OECD/NEA.

Tooling is being procured and will be tested in expected service conditions during January to I

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k Professor Neil E. Todreas 10 December 20,1988 April.

I expect that the actual samples will be cut in July, 1989 with 4

analysis and evaluation to be' completed in 1990.

I enclose for your i

i information a copy of the TMI-2 metallurgical program description that i

hr. Charles Serpan presented to the NEA/0 ECD THI-2 Project Board of Directors on November 18,1988 (Enclosure 1).

l With regard to the core, samples from the remaining disassembly and removal are being kept for archival purposes.

RES is now considering in its review of the severe accident research what reorientation and additional work is advisable. The role that the reactor vessel played in protecting the containment from the challenge of molten core material has been evident for three years. Since the discovery and mapping of the ceramic core material crucible, it is further evident that this crucible in its formation, and even in its mode of failure, very likely served to prevent vessel failure. This indicates the need to pursue further the late phase core melt progression.

This work being done, we will undertake to write a final report that pulls together the strands of the D01 core analysis program, and NRC work on remaining samples from the coro and vessel.

5 Closing If you or Committee members have any question about this response, please let me know.

1 look forward to receiving your comment about the Subcommittee meetings i

on programs. These have been lively and incisive meetings and I have learned 1

important things about the programs (I was not able to attend the Brookhaven i

meeting on the human factors program). The preparation for these meetings has provided a most positive stimulus for RES staff and contractor and laboratory i

staff as well.

I do appreciate the thought, care, and time that NSRRC is putting into review and advice on the research programs.

Sincerely, Eric S. Beckjord D r ector.

Office of Nuclear R ulatory Research l

cc: NSRRC Members l

Enclosure:

TMI-2 VIP Metallurgical Program Description I

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i TMI-2' VIP METALLURGICAL PROGRAM t

i OBJECTIVES:

i DETERMINE A SCENARIO FOR AND DEDUCE THE TEMPERATURES OF THE STEEL IN THE LOWER VESSEL HEAD DURING THE ACCIDENT.

j DETERMINE THE MECHANICAL PROPERTIES OF THE STEEL FROM THE LOWER HEAD OF THE TMI 2 REACTOR VESSEL UNDER THE CORE MELT I

ACCIDENT CONDITIONS.

j ASSESS THE INTEGRITY OF THE TMi 2 VESSEL AND THE MARGIN TO FAILURE DURING THE ACCIDENT.

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TASK A i

FABRICATION OF METALLOGRAPHIC AND MECHANICAL TEST SPECIMENS FROM TMI 2 PRESSURE VESSEL SAMPLES l

-i RECEIVE AND CATALOG THE SAMPLES FROM TMI 2.

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. VERIFY RECORDS SHOWING SAMPLE LOCATION AND ORIENTATION WITH RESPECT TO THE ROLLING DIRECTION PHOTOGRAPH SAMPLES AND RECORD SAMPLE SIZES DETiRMINE GAMMA ACTIVITY PROFILES

. PREPARE METALLOGRAPHIC AND MECHANICAL TEST l

BLANKS FROM THE SAMPLES CUT FROM THE LOWER HEAD.

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DEVELOP PRELIMINARY CUTTING DIAGRAMS AND i

PREPARE INITIAL METALLOGRAPHIC SPECIMENS

. CUT SPECIMEN BLANKS FOR DETAILED l

METALLOGRAPHIC AND MECHANICAL PROPERTIES-ANALYSES DECONTAMINATE BLANKS, MACHINE SPECIMENS, AND DISTRIBUTE TO COOPERATING PARTNER l

LABORATORIES

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TASK B ARCHIVE MATERIAL PROGRAM

• PROVIDE A SET OF STANDARDS FOR COMPARISO!;

WITH THE SAMPLES REMOVED FROM TMI 2.

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. PROCURE 5 IN. THICK A533 B STEEL PLATE l

. SUBJECT PLATE TO SAME PRE SERVICE HEAT TREATMENT AS TMI 2 LOWER HEAD

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. DETERMINE MICROSTRUCTURAL VARIATIONS IN i

THROUGH WALL THICKNESS OF ARCHIVE i

MATERIAL

. SUBJECT SPECIMENS FROM INNER 21/2 IN. OF PLATE TO RANGE OF HEAT TREATMENTS r

POSTULATED FOR TMI 2 LOWER-HEAD UNDER l

ACCIDENT CONDITIONS AND COMPARE RESULTS WITH ACTUAL MICROSTRUCTURES OF VESSEL HEAD

. IDENTIFY MOST PROBABLE-THERMAL HISTORY FOR LOWER HEAD, BASED UPON COMPARISONS OF MICROSTRUCTURES AND HARDNESS AND RESULTS i

OF THERMAL ANALYSES-

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PROVIDE MATERIAL FOR THE DETERMINATION OF THE MECHANICAL PROPERTIES OF THE LOWER HEAD DURING THE ACCIDENT.

. DEVELOP DETAILED MECHANICAL PROPERTY TEST MATRIX WITH PARTICIPATING PARTNER LABORATORIES

. SUBJECT REMAINING ARCHIVE MATERIAL TO APPROPRIATE HEAT TREATMENTS, FABRICATE MECHANICAL PROPERTY TEST SPECIMENS, AND t

DISTRIBUTE THESE SPECIMENS TO PARTNER.

LABORATORIES FOR TESTING e

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l TASK C I

MECHANICAL PROPERTY CHARACTERIZATION OF TMI 2 LOWER PRESSURE VESSEL HEAD AND ARCHIVE MATERIAL ll

. DETERMINE THE MECHANICAL PROPERTIES OF THE LOWER VESSEL HEAD AND ARCHIVE MATERIALS UNDER THE CONDITIONS-OF THE CORE MELT ACCIDENT AND ASSESS THE LOWER. HEAD INTEGRITY AND MARGIN :

TO FAILURE DURING:THE ACCIDENT.

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. MECHANICAL PROPERTIES OF INTEREST ARE.

STRESS RUPTURE, TENSILE CHARPY V AND-FRACTURE TOUGHNESS, AND HARDNESS PROPERTIES AS FUNCTIONS OF HEAT TREATMENT HISTORY AND ORIENTATION WITH RESPECT TO THE ROLLING: DIRECTION

. DETERMINE THROUGH. WALL MECHANICAL PROPERTIES VARIATIONS IN WEDGE SAMPLES

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i FROM LOWER HEAD

. DETERMINE MECHANICAL PROPERTIES OF TEST SPECIMENS FROM CORRESPONDING ARCHIVE MATERIAL AND COMPARE WITH DATA FROM LOWER l

HEAD SPECIMENS fi DETERMINE MECHANICAL-PROPERTIES OF i

ARCHIVAL MATERIAL SUBJECTED TO HEAT l

TREATMENTS INFERRED-FOR OUTER HALF CF l

LOWER HEAD i

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. INTEGRATE ALL MECHANICAL PROPERTIES AND METALLOGRAPHIC STUDIES DONE BY NON USA LABS WHO ARE PARTNERS IN THE OECD JOINT o

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PROGRAM

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e Moore and Tolman (1988) Analysis of TMI-2 Lower Head Thermal Transient j

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rod material 1

Intermediate Confiauration I,

4 Water Porous debris region (UO and Zr) 2 l_-

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Head Centerline Temperatures (Moore and Tolman,1988)

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i Intermediate case 1400 1600 E

1 1000

_ t.3,- 1200 I

- o.s, 800 800

,s.

.,o.s.

.....;*~.*.=.v....srsorer***

l 200 t

I I

I i

i 400 0

0.5 1.0 -

1.5 l

Time (h) t Time (s) t 0

1000 2000 3000 4000 5000-6000 t

2000 i

i i

i i

i i

i i

Lower bound 1400

.- 1600 E 1000 g,g,- 1200 o.s.

300 l

600

., g

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I.s'* * ' ' i i

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400 200 1

0 0.5 1.0 1.5 Time (h) i 1

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vit Illi t ig it iti si si si s i t is it'l t

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L-Expected Response of A533B Steel to Var ous Heat Treatments (From Fe-C Phase D agram at 0.25% C) 4 i

i Temo. Rance' Microstructural Resoonse i

R.T. to 727'C a + bainite; possible temper-l ing of bainite for T>600*C t

727 to 810*C BaWie+ y; increasing y with Increasing T 810 to 1480 C All y; grain growth with l

increasing time and T q

l 1480 to 1495'C y + liquid l

l 1495 to 1520*C 8 + liquid I

>1520*C Liquid I

)

i a

i i

i i_________.__.______.___.__..___.___E.#,-. _ _ _. _ _ _.. _ _ _ _ _ _. _ _. _. _.. _. _ _

l 1

t 1

IEi CONTINUOUS COOLING TRANSFORMATION DIAGRAM i

l 11 Ni Mo AUsTEumsEo AT twC PREVIOUS TREATMENT SLANK CARBURISED i

900'C 4 h A.C' ANALYSTS Wt% (See note on page 8) j C

si Mn P

5 Cr Me Ni Al Nb

-V

-l l

l L

0.24 0.20 0.$$ 0.020 0.020 0.20 0.2$

l.00 l

i 900-l

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t 700 i

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• A

• D--

v 000

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$00 s

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100 10m $2 se ip SO 20 10 3

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i COOL.ING RATE AT 700 C C PER MIN i

e i

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mm01 0.2 6.$

I-2 S

le 30 M-100

' 200 Soo 1000. 2000 mm i

AIR i

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h 1

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l Estimated Effect of Cooling Rate on I'

the Austenite Transformatlon Products for A533B Steel Cooling Rate at 700*C C/ min)

Transformation Products 1

a + pearlite + bainite i

10 a + pearlite + bainite 100 a + bainite 1,000 bainite L

10,000 bainite + martensite l

i g

l i

i l

v

- i.3 -

v

1 ISOTHERMAL HEAT TREATMENTS l

\\

l l

..... y **

• Cooling rate at l

700'C ~1'C/ min

-40'C/ min l

l

=-- 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> -+.;

TIME Tmax = 500 to 1400*C in 50'C intervals (19 temperatures total) 9 0

4 i

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TRANSIENT HEAT. TREATMENTS l

(STANDARD HEATING RATE) i l

I l

i.

l.

l l

...... T ax i

4 Three cooling rates

-40'C/ min i

i TIME Tmax = 750 to 1400 C in 50*C interval's (14 temperatures total)

Cooling rates at 700*C:

~1*C/ min

~10 C/ min i

~100*C/ min 14' I

1 l

'f

.m= / f ~

j i

TRANSIENT HEAT TREATMENTS i

(RAPID HEATING RATE) i I-

~

700'C ~10'C/ min Cooling rate at -

i.

t

)

(

% -100'C/sec l

i TIME I

T s 1000,1100,1200, and 1300'C max l

1 i

I f

t

- /.6 -

,1 i

l 1

A533B Archive Material Heat Treatment Experimental Matrix i

+

Isothermal Transient Heating rate ('C/ min) 40 40 40 40 1' 00'C/sec j

]

Cooling rate ('C/ min) 1 1

10 100_

10 k

Max. tema. f'C) 500 X

e 550 X

600 X

l 650 X

l 700 X

750 X

X X

X 800 X

X X

X 850 X

X X

X 900 X

X X-

.X 950 X

X X

X 1000 X

X X

X X

1050 X

X X

X 1100 X

X X

X X

1150 X

X X

X 1200 X

X X

X-X 1250 X

X X

X 1300 X

X X

X X

1350 X

X X

X 1400 X

X X

-X No.of specimens:

19 14 14 14 4

f' 9

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TIF-2 VIP Metallurgical Program i

o e

Planned Disbursements 10/1/88 9/30/89 ANL Authorization

$850K

.j t:RC 450K-i PECD 400K

(

s Archive Program 400K 1

Project Review & Coordinatican-50K Carryover 400K' i

l INEL l

Authoritation 450K I

NRC 150K OECO 300K Project Peview and Coordination 25K 1.

L I

Carryover 425K

~l FY '?89 Total 1300K' t

1 i

FY 1990 500K GRAND TOTAL (Including Archive)

$1800K

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