ML20149L619

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Requests Waiver for Std Required Background Checks for Listed Individuals
ML20149L619
Person / Time
Site: Maine Yankee
Issue date: 06/26/1996
From: Congel F
NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD)
To: Brady R
NRC OFFICE OF ADMINISTRATION (ADM)
Shared Package
ML20148C622 List:
References
NUDOCS 9606280247
Download: ML20149L619 (24)
v • d • e


Text

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rc 9' June'26, 1996 y

MEMORANDUM T0: Raymond J. Brady, Director Division of Security Office of Administration FROM: Frank J. Congel, Director ()tigmd Qw g. i . ,

Incident Response Division '

Office for Analysis and Evaluation of Operational Data

SUBJECT:

STANDARD BACKGROUND CHECK WAIVER I am requesting that the Division of Security waiver the standard required ]

background checks for the following individuals based on the expediency i required by the Chairman to serve on the Maine Yankee Independent Safety '

Assessment Team. I will accept full responsibility for their integrity and l have full confidence that they will maintain the highest degree of public trust during their assignment to the team.  !

DECROW, David W.- 00STIE, Patrick J.

SSN: SSN:

VANAGt Uldis WILEY, P ter J. I SSN: SSN:

If you require additional information, please contact me at 415-7476. l cc: C. Harbaugh, ADM Distribution:

File Center  ;

AE0D R/F IRD R/F ,

Ma:ine Yankee ISAT R/F -

,EJordan Dross O('gG CSiegel DISK / DOCUMENT NAME: A:\ SECURITY.MEM To receive a copy of this document, indicate in the box: "C" - Copy wlo attachment, *E" - Copy wIsttachment. "N" - No copy 0FC D:IRD:AE0D M NAME FJCongel:mgc @

J v DATE 06/2h/96  ;

0FFICIAL RECORD COPY

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ConfidentialityAgattml This Agreement between Yankee Atomic Electric Company (Yankee), a Massachusetts l

Corporation, with ofEces at 580 Man Street, Bolton, MA 01740, and

_ (Recipient)is made as of[da/d.

WHEREAS, Yankee possesses certain technical information relating to -

Safety Ana1ys i s Codes and Methods _

technology (Technology);

WHEREAS, the Technology includes, but is not limited to know-how, ideas, plans, designs and process, including software, methodologies, inteifaces and the like and includes the fact and extent of Yankee's interest in the same; i

WHEREAS, the Technology was developed or otherwise acquired by Yankee at considerable expense and is of great value to Yankee; WHEREAS, the Recipient is under contract to q.ClienLofZankee lo audit the Technoforv; and WHEREAS, the parties each wish to maintain their respective rights without making the Technology generally public or common knowledge; NOW THEREFORE, the parties hereto agree as follows: .

1. All Technology disclosed to the Recipient consists ofinformation of a proprietary or confidential r.ature (hereinafter collectively and separately referred to as "Information"). Such Information shall be in writing and clearly identified as confidential or proprietary by Yankee by marking it with an appropriate stamp or legend indicating it is confidential or proprietary. The  !

Recipient agrees that it will use the same reasonable efforts to protect such Information as it uses l i

to protect its own proprietary or confidential information. Disclosure of such Infonnation shall be restricted to those employees of the Recipient who are participating in the evaluation of the Technology. All such employees shall agree to keep the Information moprietary and confidential and to use it only pursuant to the terms of this Agreement.

2. Information is defined as, but not limited to, performance, financial, and contractual information, ideas, technical data, concepts and methodologies originated by Yankee, not previously published or otherwise disclosed to the general public, not previously available to the Recipient or others without restriction, nor normally furnished to others without compensation, and which Yankee desires to protect against unrestricted disclosure and which is furnished pursuant to this Agreement and appropriately identified as being proprietary when furnished.
3. The Recipient shall not make any reproductions, disclosures or use of such Information except as follows:

.JG-ic-36 WED 6:55 iME.EE 9 S^. 5057735 '.i  ?. Di

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a. Information furnished Yankee may be used by the Recipient solely for the purpose of this Agreement,
b. AllInfonnation furnished by Yankee and all other documentation in the possession of the Recipient relating to the Information, including, but not limited to, written notes, memoranda, and sketches, shall be returned to Yankee upon demand. The use of such Infonnation during the course of this Agreement shall not imply a j license to continue such use.

4

4. The Recipient shall not be liable for reproduction, disclosure or use ofInformation with l respect to which any of the following conditions exist

i

a. The Information is pan of the public domain or becomes part of the public domain

! through no fault ofthe Recipient.

b. The Information was known to the Recipient prior to its receipt.

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c. The Information was received from a third party without any binder of secrecy provided the Recipient did not know or have reason to know that such third party j was not entitled to disclose it.

1

d. The Recipient is obligated to produce the Information as a result of a court order

! or pursuant to government action, provided the Recipient furnishes Yankee written j notice of such court order or government action and permits Yankee to intervene

! at its expense to protect such Information.

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5. The Recipient shall not make, have made, utilize or sell any of the Technology or i Information unless specifically authorized by Yankee in writing by way of a license agreement, or otherwise.

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6. Yankee shall not be liable for the accuracy, use or misuse of any information provided.

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i 7. 'No license under any patent now or hereafter obtained is granted, agreed to be granted, er implied by either this agreement, or the disclosure of the Technology or Information.

8. The Recipient may not assign its rights, interests or obligations under this Agreement without the written consent of Yankee.
9. This Agreement shall be governed by the laws of and disputes submitted to the courts of the State of Massachusetts.
10. This Agreement represents the entire and integrated agreement between the parties and supersedes any prior and contertporaneous proposals, negotiations, representations and  ;

agreements relating to the subject matter hereof. This Agreement may be amended only by ,

written instrument signed by both parties hereto.

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11. The Recipient agrees that violation of this Agreement would cause irreparable harm to

. Yankee which could not be adequately remedied by damages and hereby consents to and agrees not to oppose a request by Yankee for and injunction or other equitable relief.

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IN WITNESS WHEREOF, the parties have caused this Agreement to be fully executed by their duly authorized officers.

! RECIPIENT YANKEE ATOMIC ELECTRIC COMPANY t

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By' Name:

2' xi 1 AIL - Name: _-

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Title:

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Title:

Date: 9-it <t e Date: _. _.-

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Confidentialitylgritmtni This Agreement between Yankee Atomic Electric Company (Yankee), a Massachusetts l Corporation, with ofEces at 580 Man Street, Bolton, MA 01740, and Dr- / v2% r We // _ (Recipient)is made as of[glatfj.

l WHEREAS, Yankee possesses certain technical information relating to -

Safety Analy s i s Codes and Methods _ technology (Technology);

l l WHEREAS, the Technology includes, but is not limited to know-how, ideas, plans, designs and process, including software, methodologies, inteifaces and the like and includes the l fact and extent of Yankee's interest in the same; WHEREAS, the Technology was developed or othenvise acquired by Yankee at considerable expense and is of great value to Yankee; WHEREAS, the Recipient is under contract to a.ChnLof Yankee to atufit the

( Technolon; and WHEREAS, the parties each wish to maintain their respective rights without making the Technology generally public or common knowledge; NOW THEREFORE, the parties hereto agree as follows:

1. All Technology disclosed to the Recipient consists ofinformation of a proprietary or confidential nature (hereinafter collectively and separately referred to as "Information"). Such Information shall be in writing and clearly identified as confidential or proprietary by Yankee by l marking it with an appropriate stamp or legend indicating it is confidential or proprietary. The l Recipient agrees that it will use the same reasonable efforts to protect such Information as it uses to protect its own proprietary or confidential Information. Disclosure of such Infonnation shall be l restricted to those employees of the Recipient who are participating in the evaluation of the Technology. All such employees shall agree to keep the Information proprietary and confidential and to use it only pursuant to the terms of this Agreement.
2. Information is de5ned as, but not limited to, performance, financial, and contractual information, ideas, technical data, concepts and methodologies originated by Yankee, not previously published or otherwise disclosed to the general public, not previously available to the j Recipient or others without restriction, nor normally furnished to others without compensation,
and which Yankee desires to protect against unrestricted disclosure and which is furnished i

pursuant to this Agreement and appropriately identified as being proprietary when furnished.

3. The Recipient shall not make any reproductions, disclosures or use of such Information l except as follows:

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a. Information furnished Yankee may be used by the Recipient solely for the purpose of this Agreement.
b. AllInformation furnished by Yankee and all other documentation in the possession of the Recipient relating to the Information, including, but not limited to, written j i

notes, memoranda, and sketches, shall be returned to Yankee upon demand. The use of such Infonnation during the course of this Agreement shall not imply a l

i license to continue such use.

4. The Recipient shall not be liable for reproduction, disclosure or use ofInformation with

!- respect to which any of the following conditions exist:

i l a. The Information is part of the public domain or becomes part of the public domain j through no fault of the Recipient.

b. The Information was known to the Recipient prior to its receipt.

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c. The Information was received from a third party without any binder of secrecy l'

provided the Recipient did not know or have reason to know that such third party was not entitled to disclose it.

I i d. The Recipient is obligated to produce the Information as a result of a court order or pursuant to government action, provided the Recipient furnishes Yankee written l

i notice of such court order or government action and permits Yankee to intervene at its expense to protect such Information.

S. The Recipient shall not make, have made, utilize or sell any of the Technology or i Information unless specifically authorized by Yankee in writing by way of a license agreement, or

! otherwise.

i 6.' Yankee shall not be liable for the accuracy, use or misuse of any information provided.

l

7. No license under any patent now or hereafk r obtained is granted, agreed to be granted, or implied by either this agreement, or the disclosure of the Techi ology orInformation, 1

) 8. The Recipient may not assign its rights, interests or obligations under this Agreement i without the written consent of Yankee.

1 9. This Agreement sh*11 be governed by the laws of and disputes submitted to the courts of 1 the State of Massachusetts.

10. This Agreement represents the entire and integrated agreement between the parties and supersedes any prior and contemporaneous proposals,, negotiations, representations and agreements relating to the subject matter hereof. This Agreement may be amended only by i written instrument signed by both parties hereto.

-,y 4 4 sG-25-96 'WED 6:55 Ys.hT.EE rp.; g, 503- gi7;t o

11. The Recipicnt agrees that violation of this Agreement would cause irreparable harm to Yankee which could not be adequately remedied by damages and hereby consents to and agrees not to oppose a request by Yankee for and injunction or other equitable relief.

1 IN WITNESS WHEREOF, the parties have caused this Agreement to be fully executed by their l l

duly authorized officers.

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RECIPIENT YANKEE ATOMIC ELECTRIC COMPANY By: ._

l' By: _ _ _ . _ _

Name: Le fh e r _ Welf Name: __. ..

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Title; frohs.ser2 A 5W O&

Title:

1 Date: O 7 / 0 3/ 78 Date: _ _ _ _ _ . . _ _ _ . _

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l ,AUG-25-96 WED s:54 YANKEE rAX O. 5057796711

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l:h Confidentialitylgr.cfmLnt l This Agreement between Yankee Atomic Electric Company (Yankee), a Massachusetts Corporation, with ofBees at 580 Man Street, Bolton, MA 01740, and 7n f ,o / & r o ne y c., (Recipient)is made as of[datrJ.

i WHEREAS, Yankee possesses certain technical infomtation relating to _.

safety Ana1 y s i s Codes and Methods _ technology (Technology);

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WHEREAS, the Technology includes, but is not limited to know-how, ideas, plans,
designs and process, including software, methodologies, interAes and the like and includes the fact and extent of Yankee's interest in the same;

't i WHEREAS, the Technology was developed or otherwise acquired by Yankee at considerable expense and is of great value to Yankee; l

i l WHEREAS, the Recipient is under commcuea cLienLofXQnkee to audit the

Technolow, nnd

! WHEREAS, the parties each wish to maintain their respective rights without making the

Technology generally public or common knowledge; l NOW THEREFORE, the parties hereto agree as follows

i 1. All Technology disclosed to the Recipient consists ofinformation of a proprietary or

confidential nature (hereinafter collectively and separately referred to as "Information"). Such Information shall be in writing and clearly identified as confidential or proprietary by Yankee by l

marking it with an appropriate stamp or legend indicating it is confidential or proprietary. The Recipient agrees that it will use the same reasonable efforts to protect such Information as it uses

to protect its own proprietary or confidential information. Disclosure of such Information shall be restricted to those employees of the Recipient who are participating in the evaluation of the
Technology. All such employees shall agree to keep the Information proprietary and confidential and to use it only pursuant to the terms of this Agreement.

J

2. Information is defined as, but not limited to, performance, financial, and contractual information, ideas, technical data, concepts and methodologies originated by Yankee, not previously published or otherwise disclosed to the general public, not previously available to the Recipient or others without restriction, nor normally furnished to others without compensation, and which Yankee desires to protect against unrestricted disclosure and which is furnished

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1 pursuant to this Agreement and appropriately identified as being proprietary when furnished.

3. The Recipient shall not make any reproductions, disclosures or use of such Information except as follows: ,

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,AUG-28-96 WED 8:55 YANKEE FAX NO. 5087796711 P.03 i \

! a. Information furnished Yankee may be used by the Recipient solely for the purpose j of this Agreement. ,

i

b. All Information furnished by Yankee and all other documentation in the possession l of the Recipient relating to the Information, including, but not limited to, written notes, memoranda, and sketches, shall be returned to Yankee upon demand. The use of such Information during the course of this Agreement shall not imply a license to continue such use.
4. The Recipient shall not be liable for reproduction, disclosure or use ofInformation with respect to which any of the following conditions exist:
a. The Information is pan of the public domain or becomes pan of the public domain through no fault of the Recipient.
b. The Information was known to the Recipient prior to its receipt.
c. The Information was received from a third party without any binder of secrecy provided the Recipient did not know or have reason to know that such third party was not entitled to disclose it.
d. The Recipient is obligated to produce the Information as a result of a coun order or pursuant to government action, provided the P acipient furnishes Yankee written notice of such court order or government action and permits Yankee to intervene at its expense to protect such Information.
5. The Recipitnt shall not make, have made, utilize or sell any of the Technology or Information unless specifically authorized by Yankee in writing by way of a license agreement, or otherwise.
6. Yankee shall not be liable for the accuracy, use or misuse of any inform;dion provided.
7. No license under any patent now or hereafter obtained is granted, agreed to be granted, Gr implied by either this agreement, or the disclosure of the Technology orInformation.
8. The Rec.ipient may not assign its rights, interests or obligations under this Agreement without the wdtten consent of Yankee.
9. This Agreement shall be governed by the laws of and disputes submitted to the courts of the State ofMassachusetts.
10. This Agreement represents the entire and integrated agreement between the panies and supersedes any prior and contemporaneous proposals, negotiations, representations and agreements relating to the subject matter hereof. This Agreement may be amended only by written instrument signed by both parties hereto.

1

,AUG-28-96 WED 8:55 YAtEE FAX 110. 5087796711  ?,04 l

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11. The Recipient agrees that violation of this Agreement would cause irreparable harm to Yankee which could not be adequately remedied by damages and hereby consents to and agrees not to oppose a request by Yankee for and injunction or other equitable relief.

IN WITNESS WHEREOF, the parties have caused this Agreement to be fully executed by their duly authorized officers. ,

l RECIPIENT YANKEE ATOMIC ELECTRIC COMPANY By: Ahl)

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YI O H NvaaGicM , Ar RsrisV I N I N C O R P O R A T E D ne.r x ,nian u. 5-5 .3 35 W , E i n .r t . n vo 4 September 22,1996 Mr. Jim Wolf Lockheed Martin Idaho Tech. Co.

PO Box 1625 Idaho Falls, ID 83415-3521 l

Dear Mr. Wolf:

I have completed my review of the Independent Safety Assessment (ISA) Team's findings on Maine Yankee's application of their codes to help insure that the facility is operated in conformance with its safety analysis.

The ISAT has done an excellent job is performing its review of Maine Yankee's analysis of chapter 15 transients, the codes used to perform these analyses and the applicability of these codes to the plant transients. They are to be commended for the fine job that i they have done in such a short period of time.

They have found, in their review, that the Main Yankee reactor transient safety analysis is very good in the area of fuel setpoint and refueling analysis which involves the Casmo, Simulate-3, Star, Frosstey, Cobra 30, SCU and Chic-Kin. The analyses performed with these codes is well documented. the codes have been appropriately assessed and validated against appropriate data, the important parameters have been identified and appropriate sensitivity studies have been performed for these important parameters. Calculations performed with these codes have a direct impact on the plant's ability to operate efficiently and therefore have a direct impact on the profitability of the plant so there is a large monetary incentive for the utility to invest the time and money in these analyses that is required to do them well. I agree with your findings that the performance of the utility in performing analysis with these codes in very good.

The ISAT has found thht the performance of the Utility in the application of system transient codes such as GEMINI and RETRAN is less acceptable. These types of transients are performed less often and have less monetary incentive so there is a tendency for the utilities to invest less effort into doing them well. I believe that this is an industry wide problem and not a problem specific to this utility.

The ISAT has determined that GEMINI is applied to very simple transients which do not require much sophistication and that it is acceptable as used in the Maine Yankee transient analysis. I agree that this is the case, however, I believe it suffers from some of the same lack of attention that the more sophisticated analyses performed with

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RETRAN suffers from. The ISAT has determined that all of the transient analyses performed with both GEMINI and RETRAN have been performed in a conservative manner and that the plant is being operated under safe conditions and can, therefore.

continue to operate. I agree with this finding.

l

! However, what I find troubling is that the utility had not done all of the necessary sensitivity studies and code assessment necessary to quantify the amount of l conservatism built into the transient analyses. They assumed that the calculations would be conservative with out demonstrating it. The ISAT questioned the results of l

some of the analyses and assumptions that went into the analyses, causing the utility to perform additional simulations and sensitivity studies to address these questions. This

! resulted in the conservatism of the analyses being demonstrated. The utility should l have done this on its own. The failure of the utitilty to do this is of concern because it is likely that, in the future, conservatisims will be removed to gain more operating margin and, when this happens, the effects of unknown, non conservatisms may result in the '

plant being operated in an unsave manner. The utility should do the necessary sensitivity studies to show that:

I; 1. They understand the important parameters for each transient that they are required i- to analyze.

2. They understand the sensitivity of transient results to variations in these parameters.  ;
3. They have evaluated each of the codes and the models in those codes to assure '

that they are capable of addressing the important parameters - i.e. that the codes are applicable to the transient analyses to which they are applied.

The utility should document the work that they have done to demonstrate the above so that it can be reviewed by the NRC and so that the knowledge will be passed on to others as utility personnel changes. The utility has initiated development of a document that identifies the important parameters for each transient as a result of the ISAT's inquiries. I commend this action and encourage the utility to complete this effort. I suggest that they use work that has already been conducted by EPRI in this regard which is documented in the Reactor Safety Support Package (RASP), EPRI NP 4498, Volume 3, May 1986.

The utility has indicated to the ISAT that they rely heavily on the code developer for assessment and validation of RETRAN. I have no problem with this as long as the Utility has the code developer review the Utility's application of the code to assure that it ,

is being app!ied conectly. Otherwise, the utility should meet the intent of Generic Letter No. 83-11 by demonstrating that it has done sufficient code assessment and sensitivity studies to show it is qualified to perform safety analyses with that code. I suggest that the utility have an independent peer review of its analyses and methodology much as the code developer's do to with the generic code.

The NRC should initiate a plan that will enforce the intent of Generic Letter No. 83-11 since the utilities do not have a large monetary incentive to do so. This should involve periodic spot checks of enn utility to assure that the utilities are appropriately

. _ - - __ _ _. - _ _ . _ _ __ - ___ _ -_ _ _ .~. _ ._ _ ,

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! performing and documenting analyses and that they are carrying out necessary activities to demonstrate that the codes are applicable to the transients being analyzed <

and that the important parameters and sensitivity of parameters are understood. The  !

NRC plan should provide incentives to the utility industry to upgrade its analytical tools by facilitating adoption of improved models when deficiencies are fo ;nd in the existing models.

It is clear from the ISAT's review, that the NRC has rot been consistent in its

' expectations for the utilities. The SERS issued for the same code contains different

)

conditions or limits on the codes use, for example. The NRC should implement a plan to assure that code review's, license applications and SERS are consistently reviewed and issued. This requires having a written plan for conducting reviews, including the identification of transients to be analyzed and the important parameters for each transient. I recommend that the NRC continue to use an independent review team to comment on its review of utilities to assure that internal organizational pressures do not bias the NRC's judgment with regard to utility license applications.

4

Sincerely, O ,

, Marvin J. Thurgood j i

MJT l Cc: Norm Lauben. NRC J

.__,_ _. _..-___,__.-m_. - _ _ _ _ _ _ . - _ _ _ _ _ . _ _ _ _ _ . - - . _ _ _ _ ~ . _ . _ _ .

09/1A/1996 17:52 001-301-548-0493 PROF.LR.LOTHAR WCLF PAGE 02

[to 6

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! Dr. Lothar T. Wolf

  • Universityof Maryland Depanment of Materials

- and Nuclear Engineering Bldg. 090, Room 2303 College Park, MD 20 742-2115 Mr. G. Norman Lauben j U.S. Nuclear Regulatory Commission OfYice of Nuclear Regulatory Research 4 RES Washington, D.C. 20555 - 0001 i

. September 16,1996 i +

I

Subject:

Copy of summary letter report on j " Peer Review of Maine Yankee Independent Safety Assessment Team Findings" '

t j RE: LMITCO Purchase Order Number: C 96 - 176102 l Appendix - A. Statement of Work l l

i

Dear Mr. Lauben:

Attached, please find a copy of my summary letter repon on the evaluation of ISAT-

findings for your information and considerations as deliverable for the purchase order number cited above.

As member of the peer review panel,1 like to thank you and your colleagues for the efforts and patience to provide us with the requested informations and answer all our questions.

Sincerely yours, j g Enclosure

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f 09/18/1996 17:.52 001-301-548-0493 PROF.DC.LOTHAR WOLF PAGE 03 1 .

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SUMMARY

LETTER REPORT-t i

PEER REVIEW OF MAINE YANKEE l l INDEPENDENT SAFETY ASSESSMENT TEAM FINDINGS I

i l

I L WOLF I Rockville, MD September 16,1996  !

The findings and conclusions provided in the following express the personal opinion of the author based upon the written technical informations provided and the two peer review panel meetings with the ISAT.

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._ . . _ _ ..__..._m__. . . . _ . - . . - . _ . . _

09/18/1996 17:52 001-301-548-0493 PPDF.DR.LOTHAR WOLF PAril 04 FOREWORD This summary letter report solely focusses on the key findings on major techn cal and organisational findings by the peer review panel.

Therefore, the conclusions, recommendations and suggestions add .s : .y issues in the context of the Maine Yankee ISAT findings from the perspcove of the peer  ;

review panel and highlights some of them which deem ofgeneric nature. l I

Technical details of computer code aspects, modeling, nodalization and valida tion l have been discussed at length during the two meetings with the ISAT and advice provided accordingly. They are beyond the scope of this summary letter report.

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09/18/1996 17:52 001-301-548-0493 PROF.DR.LOTHAR WOLF PAGE 05 4 1 O

1 1 BACKGROUND LMITCO has been chartered by U.S. NRC with the task of assembling a small, independent peer review team for evaluating the findings of the Independent Sofety i Assessment Team (ISAT), which conducted an assessment of the Maine Yankee Nuclear Power Plant. ISAT reviewed, assessed and audited the methodology, computer codes, their validation, application and results.

l Members of the peer review included:

d t Dr. H. Sullivan, LANL, Los Alamos ,

j Dr. M. Thurgood, Richland

Dr. L Wolf, UMCP, College Park
Dr. N. Zuber, ACRS observer i The peer review team met twice with the members of the ISAT, who were responsibl
for the assessment of the analytical support provided by Yankee Atomic Electric Company (YAEC) for the Maine Yankee Nuclear Power Company in the area of non-LOCA safety analyses as per Chapter 14 in the FSAR and specifically the main stearr line break and control rod assembly drop. The two meetings took place August 7
through 8 and September 12 through 13 at NRC's headquaner in Rockville, wi .
re j ISAT briefed the peer review team about its findings of field trips to YAEC. Prior to these meetings and during these meetings an enormous amount of material was
provided to the peer review team members. Additional informations were provided by ISAT during the meetings upon the request of the peer review team members.

Based upon the technical reports, written answers to ISAT questions, copies of YAEC presentation slides, publications, interview sheets, computer code summaries, briefings by and discussions with ISAT, the following observations, conclusior s and recommendations emerge.

2 TECHNICAL OBSERVATIONS AND SUGGESTIONS a) The reactor physics codes and code suites CASMO, SIMULATE - 3 and STAR receive superior licensee attention, etTective control and state - of- the

- art validation. The comparisons between measured and predicted power distributions for several MY fuel cycles demonstrate excellent agreement and a state - of the - art knowledge base in this area.

b) The fuel performence code FROSSTEY, after previous review by BPN' -staff and resultant modifications receives superior licensee attention, effective control and has been verified by comparisons with a large PWR fuel data base c) The application of the core / bundle / subchannel code COBRA 111 C in combination with the unique YAEC - 1 DNBR correlation has been previously reviewed by BPNL and receives superior licensee attention, efYective control and has been consistently applied together with the statistical combination of uncertainties.

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09/18/1995 17:52 001-301-548-0493 PRCF.DR.LOTHAR WOLF PAGE 06 2

l.

! Although the MY cycle 15 core consists of a combination of fuel from !everal i

vendors, the implemented fuel procurement procedure enforces conforniance i

with geometrical details and fabrication tolerances such, that DNBR as figure of merit remains uneffected.

d) The simplified system code GEMINI - Il for the analysis of pressure and

temperature changes for symmetrical system behavior has received acceptabh j i licensee attention. Benchmarking and validation against test data is coniidereil

, incomplete and minimal. Benchmarks against other codes are limited, some i dating back 20 years. Additional activities habe been launched upon the ISAT-request.

e) The CHIC-KIN code, originally developed by W, has been expanded by YAEC and is applied for CEA Ejection and Loss of RCS Flow events. It l received good licensee attention and necessary control. Benchmarking to the l SPERT- test data was performed by W. YAEC benchmarking against other

. codes, such as HERMITE and STAR, covers comparisons with 3 - D space -

t time kineties codes primarily for CEA Ejection events. No comparisons have i been performed with experimental loss of flow data.

I l f) The RETRAN 02 MOD 2 code is a complex system analysis code whic'1 has been developed by EPRI for the utility industry. The code is applied i worldwide, supported by the RETRAN User Group and results have been 2

widely published in the open literature and international RETRAN-Conferences YAEC was founding member and since 1981 applies RE' IRAN for the analysis of the Main Steam Line Break event for licensing purposes.

YAEC has obtained NRC-approval for analysing all non-LOCA SRP chapter i 15 transients with RETRAN for both PWR and BWR conditions.

' The code has received insufficient licensee attention as well as unsatisfhetory control in some areas, because of too much reliance on " black box" code application and benchmarking / verification efforts by others. A clear understanding of potential safety implications of some thermohydraulic

! phenomena in important components has not been fully demonstrated as incorrect models were applied in the first place, omissions, code errors :md

questionable computational results remained undetected. The combination of the above suggests YAEC is not cognizant of model and result inadequacies of this RETRAN version. No-in-house RETRAN benchmarking against well-known separate effects and integral test data existed.

i j

it i

09/18/1996 17:52 001-301-548-0493 PROF.DR.LOTHAR WOLF PAGE 07 l 3

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Upon ISAT request and persistance, YAEC launched a substantial effort in parametric sensitivity studies and presented comparisons ofits modeling approach with the 100% MSLB-experiment BT 12 in the LOBI-MOD 2 test facility. For the time being these additional justifications indicate overall ,

conservatively low primary system temperature for reactivity computation and ,

che potential for return to power. Further validation deems warranted by analyzing the complete LOBI-MOD 2 facility for BT 12 as well as BT 01 l (10% MSLB).

In addition, pressurizer data (MIT, Netherlands, Shippingport) should be fully -

evaluated and RETRAN-analyses performed accordingly.

The issue of single core versus split core modeling primarily depends upon the availability of representative mixing data in cold leg, downcomer, lower and  ;

upper plena and in the core. Proprietary vendor data for mixing may not be always representative because of scaling issues, thermal boundary cond:tions, core and plena representations. In order to keep MSLB analysis with sy:: tem codes scrutinable and traceable, it i9 suggested to treat mixing as parameter for bounding. F.xperimental plant data for asymmetric cooldown werc  ;

measured in Occonee and more detailed data were obtained in various I facilities, including the HDR-vessel, examining PTS. .

l Refmed lumped-parameter approach nodalization of the RPV upper hesd

[

region may potentially lead to too high computed recirculation flows in this region which are unrealistic and affect important primary system quantities. It is therefore suggested to keep nodalization simple but adequate and scrutinable.  !

When cold leg temparature is used for reactivity computation, the effec *. and '

degree of mixing with the HPI and boror, concentration should be accounted for.

Overconservatism in the thermohydraulic quantities during overcooling event :

may lead to safety conc:rm , :gardir,g piping, nozzle and vessel integrity.

e) The CONTEMPT / LT - 028 containment code with input from R S f F YA 93 (YAEC version of RELAP 5 / MOD 3) for LOCA mass and energy releases it YAEC's code of choice for the containment spray pump NPSH analysis For this purpose CONTEMPT was expanded with heat exchanger network capability (see publication 19% National Heat Transfer Conference, Houston TX). An elaborate iterative cycle between R5M3YA92 and CONTEMPT was  ;

used to converge on the containment pressure as input for the NPSH-evaluation. The REL \P-model for MY is extremely sophisticated while the

'.fY-containment was only presented by one single node, lumping everything into one point. In addition, the T-flash option was exercised . A parame ric study, encompassing 15 different cases for break location, size, type and various discharge coefficients and one case for 2440 MWth, was perfonned and the NPSH margin values documented.

09/20/1996 17:52 001-301-548-0493 PROF.DR.LOTHAR WOLF PAGE 08 4

i These large efforts were done to take full credit for the effect of contair-ment overpressure as MY is considered to be a pre-Reg. Guide i plant.

However, the approach, especially for inodeling the containment, must be questioned, because of the tight correlation betweeri computed sump temperature and equivalent NPSH (l* F is equivalent I foot NPSH).This level i of accuracy is unachievable by the iterative procedure chosen and containment i l

modeldeveloped forMY.

. The application of a single-node, lumped-parameter approach for the l

containment including spray and sump, together with "T-Flash" or "P-Flash" option generates final computational results which are not scrutinable.

Complete mixing with non-condensables is already achieved when using a single-node approach.

The iterative solution for the containment pressure between two, so much ,

differing models deems to be inappropriate, may have convergence diff:cultie ;  !

and seems to be an " overkill" in view of the overly simplistic containment model approach, added conservatisms and uncenainties involved. It has been reported at the 1996 National Heat Transfer Conference, Houston, TX., that two iterations between primary systems and containment codes suffice for cases where more efforts and focus went into the containment modelling with several nodes to cope with the key phenomena. It is therefore suggested to redirect efforts and focus towards the containment modelling as sump, liquid l level, sump temperatures and containment atmospheric conditions are the figures of merit for the available NPSH. Whatever containment modelling  :

approach is applied, it is recommended to validate it against sump data obtained from containment experiments in the HDR and the Battelle Model Containment.

The prediction of NPSH should also realistically account for the post-LOCA-conditions in the sump, e.g. rather than taking credit for dearcated water, debries particles from failed insulation, paint and coating particles and tiudge should be accounted for, in summary of the technical obsewations on YAEC's analytical capabilities, support and applications it is worthwile mentioning that in areas which are driven by economics YAEC's performance is very good to excellent, whereas system safhy analyses are seemingly only performed on a satisfactory bases.

3. OBSERVATIONS REGARDING YAEC's PROCEDUREf AND SUGGE_S'11QNS Upon the arrival ofISAT, the situation at YAEC with respect to in-house procedures can be summarized as follows; l

l 1. Generic RETRAN conditions werejudged unimportant on the sole basis of

( engineeringjudgement; no sensitivity analyses were performed, no documentation existed which quantify thesejudgements. YAEC should formally be requested to establisch a procedure for tracking Generic SER items and restrictions which is scrutinable.

m i

09/18/1996 17: 52 001-301-548-0493 PRCC.DR.LOTHAR WOLF PAGE 09 4

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2.' No in-house procedure existed to review new code versions and to track disposition of errors and assess potential discrepancies upon licensing analysis by comparing with the previous version.

3, Lack of a cple-specific data reference document as a unique and encompassing collection of all input data. (YAEC is developing this capability now).

4. Inability to reconstruct decks for older code versions; their model and solutions procedures because of poor decumentation two decades ago, although YAEC relics heavily on the benchmarks performed then. In view of'a foreseeable generation change over, it is suggested that YAEC updates the old documentation and edds all modifications and benchmarkings to it. This is best done in the overall context of a Documentation Management System.
5. Deficiencies in benchmarking and validation of computer codes and models against integral and separate affect tests. Comparisons performed thus far separated the component from the system behavior by supplying the appropriate boundary conditions. It is suggested that YAFC shows a more proactive attitude towards validation efforts with data from scaled experimcatal facilities and plant data when available
6. Insights and leaming effects from reactor safety experiments, some of which even co sponsored by YAEC, were not used and implemented into current code version ;
7. Lack of understanding and documentation of thermalhydraulic key phenomena, parameters and their sensitivities
8. Weaknesses in interpreting important code results in the context of underlying model assumptions
9. Inconsistent conformance with QA-procedures 10.YAEC failed to compley with GL-83-11
11. Numerous added conservatisms seem to indicate that the best-estimate valu:s of important quantities are unknown and that the major content of physical and engineering processes gets lost
12. Existing documentation did not reflet current status, degree of margin 13 Lack of self-assessment in certain, mostly T/H related areas During the assessment period and as result ofISATs detailed questions, YAEC statY and management changed attitude and launched the following activities:

09/18/1996 17:52 001-301-548-0493 PRDr.DR.LOTHAR WOLF PAGE 10 6

a) Initiation of the writeup of a " Methods Overview Manual"(MOM) which lists all important key inputs, quality control and safety analysis methods in a stmrtured.

, consistant manner. It also addresses the respective code capability and applicability SER restrictions and conformance are listed.

b) Additional sensitivity studies and comparisons with data, other codes and other code versions c) Detailed answers to written questions, by ISAT which provided additional insights and informations not otherwise documented

d) Proactive responses, initiatives and issue resolutions (SG tube repture, LOCA l PLHGRs) for which YAEC can be commended i
4. QBSERVATIONS REGARDING NRC's PROCEDURES AND SUGGESTIQN_S

, The findings of the ISAT and the review by the peer review team can be summarized as follows:

1. A formal procedure, QA procedures and guidance shocid be established for the disposition of restrictions / conditions which are imposed on codes, methods, 3

assumptions in SERs tranmitted to licensees.

2. The current lack of follow - up on requirements and requests necessitates the j 4

implementation of a coherent intemal procedure ,

1 a

3. Presently, strikmg inconsistencies exist between plant-specific and generic SERs.

In the future, NRC should ensure consistancy among SERs for different plants using the same computer code (and version) for the same transient. A procedure should be established which guarantees that plant-specific SERs always contain the total set of conditions as specified in the generic SERs.

l

4. Specifically for MY, the ISAT findings must be followed up, addressed and

, effectively controlled when YAEC uses RETRAN 02 MOD 5 in the future.

5. As follow-up on GL-83.11, NRC must make shure that industry carries the full responsibility of proof, quality and adequate resources to assure safety. An enforcement and control mechanism must be in place.
6. For transients and non-LOCA events, no rule and no basis for the control of validation exist. However, these must be correctly analyzed in the context o' physical and engeneering processes. The performance of a peer review process is recommended.

09/18/1996 17:52 001-301-548-0493 PR0r M.LOTHAR WOLF PAGE 11 Y

o

7. Currently, no structure exists at NRC which would allow to collect all informations about a specific code such, that a unique set of concerns could be I established. It is recommended to improve intra-agency communication for'his l

purpose and to establish such a document data bank.  ;

8. NRC should focus attention to successful plant cooldown and demonstratiori of long-term coolability following all kinds of events and accidents.
9. At the occasion of MY ISA, it deems appropriate to review the following items: I s tracking of restrictions i

e validation ofcodes for transients  ;

E code relicensing issue l E NRC review process E SRP update a quality of reviews (LOCA vs. transients) e quality of communications with industry a completeness ofdocumentation i

10. After closure of MY issues, the ISAT should document strengths and weaknesses '

of the exercised assessment process for further and future optmization and application.

5. OBSERVATIONS ON ISAT EFFORT AND ACCOMPLISHMENTS Never before has NRC undertaken such an effort covering such broad spectrum of issues during a brief period of time.

ISAT should be commanded for its efforts, because of:

a) excellent combination of different skills,long-time experience and detailed code and code application knowhow b) focussed approach on CEA drop and MSLB covered the whole spectrum of codes c) Exhaustive list of RFI, questions, requests for sensitivity studies parameter changes

! d) uncovering new safety-related open issues (NPSH) 4 e) demonstrating deficencies in YAEC understanding, code application, result interpretation, code benchmarking and validation

~

f) efforts for MY ISA can serve future activities needed at different sites g) collection ofinformations on current status may be the basis for necessary

, improvements both in industry and agency.

INDEPENDENT GOVERNMENT COST EST: MATE SEQUENCE CODING SEARCH SYSTEM (SCSS). JOB CODE A9134 TASK 11. TECHNICAL ASSISTANCE TO 5UPPCRI AN.!NDEPENDENT SAFETY ASSESSMEN' LABOR:

HQl)P5 RATE' CHST ORNL.NOAC Senior Manager 4B W =S Administrative Support 32 =6 JBF Subcontractor PRA Expert 428 -6 TOTAL LABOR = 60940 TRAVEL To Rockville 4 trips @ N ' trip =

Per diem in Rockville 23 davs @ 'dav =

To site 2 trips @ trip =

Per diem at site 24 days @ M iddy =

~

TOTAL TRAVEL = 10406 '

TOTAL LABOR & TRAVEL = '1346

' Rate estimates includes: overhead. fringe Denefits. G&A and fee li any W j,/ g )b v'/ i.

PEV!EWED L-ffhe A L,A, / 6iA Techn'ca~ Mon 1(Cr 7 < [3te APPROVED. j4 k < M.4c . - e , t 7c Preject Manager f :e:e

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t UNITED STATES a R NUCLEAR REGULATORY COMMISSION

'f WASHINGTON. D.C. 2055r4001 June 13, 1996

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MEMORANDUM T0: Thomas L. Harrison, Chief Administrative Services Branch Division o Resource Management Reg n J

FROM: dif ard L br an Nor Office or Analysis and Evaluation of 0 erational Data

SUBJECT:

ACCESS TO RADIOLOGICAL, VITAL, AND PROTECTED AREAS Please forward the following information to Maine Yankee Atomic Power Company in connection with the temporary. assignments of Harold 0. Christensen, Ronald L. Lloyd, Alan L. Madison, Thomas 0. Martin, Ellis W. Merschoff, Jack E. Rosenthal and Ola B. West to the Maine Yankee Power Station for the advance site visit from June 20-21, 1996.

This certifies that Ellis W. Merschoff, Ronald L. Lloyd, Harold 0.

Christensen, Thomas 0. Martin and Alan L. Madi on have attended generic physicalsecurityandradiationprotection(10;{CFR19.12)trainingpreceding the planned visit date indicated. Each is capable of safe conduct in a radiologically restricted area. Accordingly, unescorted access is requested for these individuals to all plant radiological areas, excluding those requiring respiratory protection.

This also certifies that Ellis W. Merschoff, Ronald L. Lloyd, Harold O.

Christensen, Thomas 0. Martin, Ola B. West, Alan L. Madison and Jack E. Rosenthal are employees of the U.S. Nu:: lear Regulatory Commission.

Messrs Herschoff, Lloyd, Christensen, Martin, Madison and Rosenthal possess a "Q" access clearance, while Ms. West possess an "L" clearance. To my knowledge, they do not exhibit adverse character traits or aberrant behavior.

Specific security clearance informatior} is provided below:

Name Oraanization Badae Clearance , S_S1 ,

Ellis W. Merschoff RII A-2004 Q

\

Ola B. West RII B-2059 L Ronald L. Lloyd AE0D A-6471 Q \

Harold O. Christensen RII A-2041 Q Thomas 0. Martin RES A-7188 Q Alan L. Madison AE00 A-6950 Q ,

Jack E. Rosenthal AE0D A6661 Q ,-

Questions concerning this information may be directed to me (301-415-7472) or Ellis Merschoff at (301-415-6954).

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June 13, 1996 MEMORANDUM T0: Thomas L. Harrison, Chief Administrative Services Branch Division of Resource Management Region I FROM: Edward L. Jordan, Directo iginal Signed by:

Office for Analysis and E iwdO4 fan of Operational Data

SUBJECT:

ACCESS TO RADIOLOGICAL, VITAL, AND PROTECTED AREAS Please forward the following information to Maine Yankee Atomic Power Company in connection with the temporary assignments of Harold O. Christensen, Ronald L. Lloyd, Alan L. Madison, Thomas 0. Martin, Ellis W. Merschoff, Jack E. Rosenthal and Ola B. West to the Maine Yankee Power Station for the advance site visit from June 20-21, 1996.

This certifies that Ellis W. Merschoff, Ronald L. Lloyd, Harold O.

Christenssn, Thomas 0. Martin and Alan L. Madison have attended generic physical security and radiation protection (10 CFR 19.12) training preceding the planned visit date indicated. Each is capable of safe conduct in a radiologically restricted area. Accordingly, unescorted access is requested for these individuals to all plant radiological areas, excluding those requiring respiratory protection.

This also certifies that Ellis W. Merschoff, Ronald L. Lloyd, Harold 0.

Christensen, Thomas 0. Martin, Ola B. West, Alan L. Madison, and Jack E. Rosenthal are employees of the U.S. Nuclear Regulatory Commission.

Messrs Herschoff, Lloyd, Christensen, Martin, Madison and Rosenthal possess a "Q" access clearance, while Ms. West possess an "L" clearance. To my knowledge, they do not exhibit adverse character traits or aberrant behavior.

Specific security clearance information is provided below:

Name Oraanization Badge Clearance SS#

. . ~ ..

Ellis W. Merschoff RII A-2004 Q Ola B. West RII B-2059 L Ronald L. Lloyd AE00 A-6471 Q  ;

Harold O. Christensen Ril A-2041 Q j Thomas 0. Martin RES A-7188 Q i

j Alan L. Madison AE0D A-6950 Q ,

Jar.k E. Rosenthal AE0D A-6661 Q .

e ,,  !

Questions concerning this information may be directed to me (301-415-7472) or Ellis Merschoff at (301-415-6954).

DOCUMENT NAME:G:\DEIIB\DEPFILES\D0916\G0001 To receive e sepy of this decwnent. indicate in the bar: "C" - Copy a,9hout enclosures *E" - Copy with enclosures "N" - No copy 0FFICE AE98IO// l AE00:2 97,/F I NAME Efi'6546off:obw ELJo h nf ,

DATE ., 4f/f6/96 06// S/96 06/ /96 06/ /96 06/ /96 l OFFICIAL RECORD r.0PY

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Los Alamos N A Tio N A L LAe o nA?0tly Tech & Sekry Assenement Dtvisum TSA 11, uste Rsk and Hazar:3 Analysis. MS K557 Los Alamos. New MeWco 87545 (505) ti67-6231, FAX (505) 667 5531

\

September 19,1996

Dear Mr. Lauben:

l Independent Review of Yankee Atomic Electric Company Non-Loss-of Coolant j Accident Safety Analysis I would like to start by thanking the Nuclear Regulatory Cormnission (NRC) and Idaho National Engineering Laboratory (INEL) consultants who were widi us for 2 days answering questions:

i sharing information obtained during their reviews, their insights, and work they had donc in developing their conclusions: providing suggestions: and guiding us through a large amount of

documentation and technical issues. I was appreciative of their candor, technical competence,

, and ability to identify major issues, which guided me to a good understanding of the overall issues.

It was difficult to keep from focusing solely on the interesting technical issues that the staff presented and, instead, to keep focused on determining root causes and how processes can be improved so that the Yankcc Atomic Electric Company (YAEC) reviews would not have been necessary. The staff did find some issues that need to be addressed m Y AEC and at the NRC, and my comments on the.se are given below. I have divided my comments into three arcas: areas

of improvement for YAEC, areas of improvement for NRC, and conclusions.

AREAS OF IMPROVEMENT FOR YAEC Several improvements were identified during ISAT reviews of non-loss-of<oolant accident (non-LOCA) transients. Validating codes using experimental data to ensure that models and

nodalizations can adequately represent the nuclear plant and ensuring that restrictions are properly
implemented in code application are the major areas of improvement.

Formal validation of codes related to areas of application The lack of a fonnal validation effon appears to be a problem in the YAEC analytical effort for non-LOCA transients. I believe that it is necessary to validate code calculations by comparing them with experimental separate-effect.s and integral-system experiments before using a thermal-hydraulic code and associated nodalization in modeling reactor system components. A great deal of carc is requited in selecting the number of nodes for a reactor system, and the nodalization should be vahdated using experimental data that provide valuable information related to the analytical methods. By perforudng these validations, the personnel obtain a better understanding of code models and the nodaliention requhrments of applying the code to a plant transient.

Understanding of code models and we in applications It appears that Y AFC needs additional knowledge of computer code analytical models in order to y-apph c~pf t. , thermal-hydraulic codes. Details of the models in the RETRAN f&lhhb . ,

_7 l ; INi Bi; 9-1o-30 .

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1 code have caused errors and inconsistencies in the pressun7er and upper head calculations. It is

- suggested that YAEC obtain additional expertise to suppon them in this area.

NRC restrictions implemented in a formal process A number of restrictions have been placed on the Y AEC computer endes used in the licensing of Maine Yankee. There appears to be no fonnal process for responding to these limitations or l

ensuring that restnctions are included properly m their calculations. In the steady-state fuel

! performance code FROSSTEY, the restriction on burnup was 60,000 mwd /MTU and is

! controlled through a technical speci6caiion. In the thermal-hydraulic code ama, YAEC said that I

only steam was removed form the secondary side of the steam generators, whereas, in actuality, l l small amounts of liquid are released YAEC needs to have a formal process to resolve how restrictions am enforced.

l i Mmatain consistency in code applications YAEC's technical capabilities are not consistent in the technical areas required for non-LOCA transients. The quality of their thermal-hydraulic code applications and validations needs to be

. improved. Y AEC's documentation did not support the conclusions that were developed, and the conclusions were justified only after ISAT iequested sensitivity studies. Often subtle changes in options in analytical models and/or changes in nodalization affect the results Application personnel need to be aware of these subtle differences when modeling complex systems.

AREAS OF IMPROVEMENT FOR NRC I have noted six areas where NRC can improve their systems that may help prevent this situation from happening in the futun:. These six areas were discussed in the meeting. Some are relatively easy to implement in an action plan; others will require changes to documentation such as the Standard Review Plan (SRP) and may take longer.

Code restrictions required by SERs not tracked It appears from the disctissions in the meetings that several SER code restrictions were identified in NRC reviews. These apparently were not closed out with YAEC or tracked wititin the NRC systems related to code reviews. Because the restrictions were not tracked, they were not closed out in later reviews.

1 Code validation not required for application .ofinterest l NRC should consider requiring the vendors and utilitics to validate their codes using ,

experimental data from separate-effects and integral-systems experiments. This was suggested to l the code users after the Three-Mile Island accident in a memo from NRC. It is suggested that NRC consider developing requirements and ensurmg that a validation process is used.

NRC review process not complete and documentation needs to be upgraded Fmm the limited documentation given for the RETRAN SERs,it is difficult to determine the l extent of the review that was performed and bow the 39 restnctions were developed in September 1984. It is also difficult to determine why no restrictions were included in the SER m October 1985. Including specific documentation requirements in a nuxlified SRP would limit i this issue.

i F NRC has a review process that develops a SER containing important restrictions l These restrictions are developed and documented. In the RETR AN review process of September 1984,39 restrictions wete issued;in the October 1985 RETRAN review, no restrictions applied.

l l

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3ENT BY: 9-10-30 l coFX N-t LANL-  : 4 .

q, A number of crrors and inconsistencies were identified in the ISAT review of RETR AN. Based on the discussion, it appears that the mot causes are not covered in enough detail in the SER and 1 the reviews are not fully documented. It is suggested that the review quality needs to be impmved by improving the SRP and conforming to the updated SRP. It also appears that management reviews did not find the problems and independent reviews had similar results. The updated SRP review needs to include details on what phenomena are imponant, the depth of reviews needed, '

and what guidance is needed. An EPRI review plan was availabic, and a quick review of their process indicated it was more rigorous because EPRI includes discussion of topics such as assumptions made, modeling phenomena, safety systems to be considered, use of analyscs, and useful suggestions. This document could he the starting point for a rewrite of the SRP, NRC documentation did not support the conclusions Before the IS AT review, the documentation at both the vendors and within NRC did not support the modeling assessments or the degree to which the models predicted the phenomena associated with the transients. The ISAT staff requested several sensitivity studies before the conservatism could be determined. As noted earlier, several errors and inconsistencies were identified.

Computer code licensing is a disincentive for both vendors and NRC New computer codes are becoming available from a number of sources. Thesc codes have I improved abilities to predict important phenomena m non LOCA transtents. Because of the I cxtensive reviews for the cununt code licensing process, new and improved codes tend not to be considered when an analysis tool has been approved, which can be a disadvantage for the vendor, the utilitics, and the NRC. This may become a more important issue as conservatism is ,

reduced. NRC should reexamine its procedures and requirements for code licensing, try to  !

establish a more citicient process, and try to reduce approval time. Vendors and utilities need to have an incentive to improve license codes that could lead to improved safety.

CONCLUSIONS l

YAEC and NRC have an opportunity to improve inethods and review pmccsses to provide additional confidence that, m the future, non-LOCA transients arc fully justified and representative. I believe, as do most of the independent reviewers and NRC staff, that the YAEC power plant is safe to continue mnning at the cuntat power limits. The pmblems identified arc (1) fully demonstrating the degree of conservatism, (2) the lack of code modeling validation to demonstrate that nodalization is adequate for the models, and (3) improving consistency in modeling related to non LOCA transients. Both YAEC and NRC need to consider how to improve quality in both applications and reviews and how to develop new ways to reduce time and funding for getting codes approved or new analytical methods into place.

If you have any questions about my comments, please feel free to contact me at (505) 667-6231 (phone), (505) 667-5531 (fax), or hsullivan@lant. gov (e-mail).

Sincerely, Harold Sullivan LHS/ met

L'. L. J . .. ,

e i

i Los Alamos NAt#0 sat t a g o n A

  • 0 ri v Technology & Sohrry Assessment Dwisson l TSA-11. FNobatAste Rsk and Maza~.1 ArWysa MS K55, ,

_ns hamos. New Medco 87545  !

CS) f47 6231. FAX (505) 667 5531 l

September 19.1996

Dear Mr. Lauben:

Independent Review of Yankee Atomic Electric Company Non-Loss of Coolant Accident Safety Analysis I would hke to start by thanking the Nuclear Regulatory Conumssmn (NRC) and Idaho National l Engineering Laboratory @GL) consultants who were with us for .' days answering questions:

shanng information obtamed during their resiew' their insights, and work they had done m ,

developing their conchisions; providing suggestions; and guiding us through a large amount of documentation and technical issues. I was appreciatise of their candor, technical competence, and ability to identify major issues, which guided me to a good understanding of the overall issues.

It was difficult to keep from focusing solely on the interestmg techmcal issues that the statt presented and, instead, to keep focused on determining root causes and how processes can be improved so that the Yankcc Atomic Electric Company (YAEC) reviews would not have been necessary. The staff did fmd some issues that need to be addressed m Y AEC and at the NRC, and my comments on the.se are given below. I have divided my comments into three areas: areas of improvement for YAEC, arras of improsement for NRC, and conclusions.

AREAS OF IMPROVEMENT FOR YAEC Several improvements were identified during ISAT review s of non-loss-of-coolant accident (non-LOCA) transients. Vahdating codes using expenmental data to ensure that models and nodalizations can adequately represent the nuclear plant and ensuring that restnetions are properly implemented in code application are the major areas ofimprovement.

Formal validation of codes related to areas of application The lack of a formal validation effort appears to be a problem in the YAEC analytical ellort tot non-LOCA transients. I believe that it is necessary to validate code calculations by comparing them with experimental separate-effect.s and integral system expenments before usmg a themial-hydraulic code and associated nodalizat.an in modeling reactor system components. A great deal l of care is required in selecting the number of nodes for a reactor system, and the nodalization should be vahdated using experimental data that provide valuable information related to the j analytical methods. By performing these validations, the personnel obtam a better understanding l of code models and the nodahtation requiirments of applying the code to a plant transient.

l Understanding of code models and use in applications h appears that Y AFC needs additional knowledge of computer code analytical models in order to correctly apply some of their thermal-hydraulic codes. Details of the models in the RETRAN

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! 2 l i code have caused errors and inconsistencies in the press un7er and upper head calculations. It is suggested that YAEC obtain additonal expertise to support them m this area NRC restrictions implemented in a formal process A number of restricuans have been placed on the YAEC computer codes used in the been,ing of Maine Yankee. There appears to be no fonnal process for responding to these limitations or ensunng that restncuons are included properly in their calculauons. In the steady state fuel l j

performance code PROSSTEY, the restriction on burnup was 60,000 mwd /MTU and is l

controlled through a technical specification in the thermal hydraulic code ama YAEC said that

only steam was removed form the secondarv side of the steam generators. u.hereas. in actualits, small amounts of liquid are released. YAEC needs to have a formal piocess to resolve how i restnctions am enforced.

Simntain consistency in code applications YAECN technical capabihtie3 are not consistent in the techmcal areas requtred for non-l.OCA l transients. The quality of their thennal. hydraulic code applications and validanons needs to be l improved. Y AEC's documentation did not support the conclusions that were developed, and the l conclusions were justified only atter IS AT iequested sensinvity studies. Often subtle chances in  ;

i options m analyucal models and/or changes in nodahzation affect the results Appheation personnel need to be aware of these subtle differences when modeling complex systems.

AREAS OF IMPROVEMENT FOR NRC I have noted six areas where NRC can tmprove their systems that may help prevent this ,.tuation from happening in the future. These six amas were discussed in the meeting. Some are relatively easy to implement in an action plan; others will require changes to documentation such as the Standard Review Plan (SRP) and may take longer.

Code restrictions required by SERs not tracked It appears fmm the discussions m the meetings that several SER code restrictions wcre identified in NRC reviews. These apparently were not closed out with YAEC or tracked wititin the NRC systems related to code reviews. Because the restriuions were not tracked, they were not closed out in later reviews.

Code validation not required for applications of interest NRC should consider requiring the vendors and utilitics to validate their codes using ,

experimental data from separate-effects and integral-systems experiments. This was suggested to  !

the code users after the Three-Mile Island accident in a memo from NRC. It is suggested that  !

NRC consider developing requirements and ensurmg that a validation process is used. l NRC review process not complete and documentation needs to be upgraded l From the limited documentation given for the RETRAN SERs, it is difficult to determine the extent of the review that was performed and how the 39 restnctions were developed in 4 September 1984. It is also difficult to determine why no restnctions were included in the SER m j i

October 1985. Including specific documentatio3 requirements in a unxlified SRP would limit this issue.

NRC has a review process that develops a SER containing important restrictions These restrictions are developed and documentca. In the RETR AN review pmcess of September 1984,39 restrictions were issued;in the October 1985 RETRAN review, no restrictions applied.

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A number of ctrors and inconmtencies were id 9tified in the ISAT review of RETR AN Based l on the discussion,it appears that the root causes ale not covered m enough detail in the SER and l

the reviews are not fully documented. It is suggested that the review quality needs to be imprmed i

by improving the SRP and conforrmng to the updated SRP. It also appears that management ieviews did not find the problems and independent resiews had similar results. The updated SRP review needs to include details on what phenomena are imponant, the depth of reviews needed.

and what guidance is needed. An EPRI review plan was avadable, and a quick review of their process indicated it was more ngorous because EPRI includes discussion of topics such a3 assumptions made, modeling phenomena, safety sptems to be considered, use of analyscs, and useful suggestions. Tids document could be the starting pomt for a rewrite of the SRP.

NRC documentation did not support the conclusions Before the IS AT review, the documentation at both the vendors and within NRC did not suppon the modeling assessments or the degree to which the models predicted the phenomena associamd with the transients. The ISAT staff requested several sensitivity studies before the consen ausm could be detern'ined. As noted earlier, seseral errors and inconsistencies were identified.

Computer code licensing is a disincenti.e for both vendors and NRC New computer codes are becoimag available from a number of sources. These codes have improved ahdities to predict important phenomena m non-LOCA transients. Because of the extensive reviews for the curren' code licensing process, new and improved codes tend not to it considered when an analysis tool has been approved, which can be a disadvantage for the vendor, the utilitics, and the NRC. This may become a more unportant issue as conservatism is reduced. NRC should reexamine its procedures and requirements for code licensmg, try to establish a more ctiicient process, and try to reduce appmval time. Vendors and utilities need to have an incentive to improve license codes that could lead to improved safety.

CONCLUSIONS Y AEC and NRC have an opportumty to improse methods and review processes to provide additional confidence that,in the futurr, non-LOCA transients are fully justitied and representative. I believe, as do most of the independent reviewers and NRC staff, that the Y AEC power plant is safe to continue running at the current power limits. The problemudentified are (li fully demonstrating the degree of conservatism, O the lack of code modeling validation to demonstrate that nodalization is adequate for the models, and t 3)improsing consistency in modeling related to non-LOCA transients. Both YAEC and NRC need to consider how to improve quality in both applications and reviews and how to develop new ways to reduce time and lunding for getting codes approved or new analytical methods into place.

if you have any questions about my comments, please teel free to contact me at (505) 667-6231 tphone), (505) 667-5531 (faxt or hsullivan@lani. gov (e-mailt Sinccrcly, Harold Sullivan LHS/ met

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UNITED STATES D

j I ( , f NUCLEAR REGULATORY COMMISSION .

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I V WASHINGTON. O C. 2055s t Feoruary E, 19?3 TO ALL OPERATING REACTOR LICENSEES

SUBJECT:

LICENSEE QUALIFICATION FOR /ERFORMING SAFETY ANALYSES IN SUPPORT OF LICENSING ACTIONS (Generic Letter No. 8311)

Gentlemen:

The purpose of this letter is to inform you of the current NRR practice regarding licensee qualification for performing safety analyses in support of licensing actions.

Over the past few years, the number of licensees electing to perform their own safety analyses to support reload applications, technical specification amendrents, etc... rather than contract the work out to their NSSS vendor or other orcanizations has increased substantially. We encourage utilities to perform their own safety analyses since it significantly improves their understanding of plant behavior.

YsC's experience with safety analyses using larce, complex thermal-hydraulic computer codes such as RELAP and TRAC has shown that a large percentage of all .rrors or discrepancies discovered in safety analyses can be traced to toe ..ser rather than to the code itself. This realization has led NRR to o' ce additinnal emphasis on assuring the capPhilities of the code users as well as on the codes themselves. For example, for the past two years NPR nas been working with the Vendor Inspection Branch in Region IV to in-spect the acceptability of the QA procedures used for code development, veri fication, use, and maintenance for all licensees and vendors involved w i th safety analysis codes presentl y under staf f review. While this aspect nt ou r review focuses primarily on the competence of the licensee and vendors reqarding quality assurance practices, the technical competence of the licensees'and vendors with respect to their ability to set up an input deck,

..xecute a code, and properly interpret the results must also be assured.

NRR obtains this assurance by reviewing the code verification information s n mitted Dy the licensee or vendor. The information we look for includes c3rDart snns performed Dy the user of the code results to experimental data, a: ant ooerational data, or other benchmarked analyses.

Fe are concerned however, that some licensees planning to perform their owr saf ety analyses nay not intend to demonstrate their ability to use the He hv nerformina their own code verification. Rather, they plan to rely or ne code verification work previously perf ormed Dv the code developer l' J!ners.

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  • i NRR does not consider this acceptable and each licensee or vendor who intends to use a safety analysis computer code to support licensing actions should demonstrate their proficiency in using the code by submitting code verifi-cation performed by them, not others, in order to eliminate problems on future licensing submittals, I request that you factor this into your futur licensing submittal plans.

- 'J 3/ Yi Q' U1 rector U3rre[l1G.E'isenh[u,f(

Division of Licensing i

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