Information Notice 1997-15, Reporting of Errors and Changes in Large-Break Loss-of-Coolant Accident Evaluation Models of Fuel Vendors and Compliance with 10 CFR 50. 46(a)(3)

Reporting of Errors and Changes in Large-Break Loss-of-Coolant Accident Evaluation Models of Fuel Vendors and Compliance with 10 CFR 50. 46(a)(3)

ML031050354
Person / Time
Site:	Beaver Valley, Millstone, Hatch, Monticello, Calvert Cliffs, Dresden, Davis Besse, Peach Bottom, Browns Ferry, Salem, Oconee, Mcguire, Nine Mile Point, Palisades, Palo Verde, Perry, Indian Point, Fermi, Kewaunee, Catawba, Harris, Wolf Creek, Saint Lucie, Point Beach, Oyster Creek, Watts Bar, Hope Creek, Grand Gulf, Cooper, Sequoyah, Byron, Pilgrim, Arkansas Nuclear, Three Mile Island, Braidwood, Susquehanna, Summer, Prairie Island, Columbia, Seabrook, Brunswick, Surry, Limerick, North Anna, Turkey Point, River Bend, Vermont Yankee, Crystal River, Haddam Neck, Ginna, Diablo Canyon, Callaway, Vogtle, Waterford, Duane Arnold, Farley, Robinson, Clinton, South Texas, San Onofre, Cook, Comanche Peak, Yankee Rowe, Maine Yankee, Quad Cities, Humboldt Bay, La Crosse, Big Rock Point, Rancho Seco, Zion, Midland, Bellefonte, Fort Calhoun, FitzPatrick, McGuire, LaSalle, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant
Issue date:	04/04/1997
From:	Martin T Office of Nuclear Reactor Regulation
To:
References
IN-97-015, NUDOCS 9704010232
Download: ML031050354 (9)

KU

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555-0001 April 4,1997 NRC INFORMATION NOTICE 97-15: REPORTING OF ERRORS AND CHANGES IN

LARGE-BREAK LOSS-OF-COOLANT ACCIDENT

EVALUATION MODELS OF FUEL VENDORS AND

COMPLIANCE WITH 10 CFR 50.46(a)(3)

Addressees

All holders of operating licenses or construction permits for nuclear power reactors and all

reactor fuel vendors.

Purpose

The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice to alert

addressees about two recent staff findings related to the review of large-break (LB) loss-of- coolant accident (LOCA) emergency core cooling system (ECCS) analysis evaluation model

changes and also to remind licensees and reactor fuel vendors of the requirements contained

in Section 50.46(a)(3) of Title 10 of the Code of Federal Regulations [10 CFR 50.46(a)(3)]

concerning the reporting of ECCS cooling model changes and errors. It is expected that

recipients will review the information for applicability to their facilities and consider actions, as

appropriate, to avoid similar problems. However, suggestions contained in this information

notice are not NRC requirements; therefore, no specific action or written response is

required.

Description of Circumstances

Recently identified changes and errors in Siemens Power Corporation (SPC, formerly Exxon

Nuclear) and General Electric (GE) LBLOCA analysis models have led to a series of 30-day

reports and 10 CFR 50.72 reports as required by 10 CFR 50.46, "Acceptance Criteria for

Emergency Core Cooling Systems for Light Water Nuclear Power Reactors."

SPC LBLOCA ECCS Evaluation Model Changes

The SPC LBLOCA ECCS model, TOODEE2, was approved by the NRC staff to meet the

requirements of 10 CFR 50.46 in a letter dated July 8, 1986 [Accession number

8607150319], from D. M. Crutchfield (NRC) to G. Ward (Exxon). In 1991, SPC had made

changes to the NRC-approved fuel cooling test facility (FCTF) reflood heat transfer coefficient

correlation used in TOODEE2.

During August 1995, the NRC met with SPC about the LBLOCA ECCS evaluation model. As

a result of that meeting, the staff sent a letter to SPC, dated November 13, 1995

[95111502111, that identified problems concerning changes in the TOODEE2 computer code

4;;;mA Troy E~DTIC-

V6 97 -01r P011.0X \\C

K>

IN 97-15 April 4, 1997 specifically related to the 1991 changes to the NRC-approved FCTF reflood heat transfer

coefficient correlation and the significance of the code changes. The staff then requested in

a letter dated March 13, 1996 [9603150002], that SPC formally submit to the staff for its

review and approval all model revisions and corrections implemented in TOODEE2 since the

staffs approval of the code in July 1986.

On June 2, 1996, SPC submitted topical report XN-NF-82-20, "EXEM/PWR Large Break

LOCA ECCS TOODEE2 Updates," Revision 1, Supplement 5 [9606260239], which described

the updates made in the TOODEE2 computer code between 1986 and 1991. TOODEE2 is

part of the evaluation model used by SPC for pressurized-water reactors. The staff has

completed its review of this report and has concluded that the proposed LBLOCA-ECCS

model (i.e., the 1991 model) is not acceptable and the previously approved model (i.e., the

1986 model) contains an unacceptable error. This information was formally communicated to

SPC in a safety evaluation enclosed in a letter dated November 29, 1996 [9612040294).

After concluding that the 1991 model was unacceptable, the staff met with SPC and those

licensees using SPC's LBLOCA evaluation model on October 16, 1996, to discuss the

unacceptable error in the 1986 model. The staff also requested and received information

from the licensees that demonstrated that they were in compliance with 10 CFR 50.46 (see

meeting summary dated November 5, 1996 [9611140318]).

Public Service Electric & Gas (PSE&G) Audit of GE

During a recent licensee-conducted quality assurance (QA) audit of the fuel vendor (GE -

Wilmington, North Carolina), PSE&G, the licensee of Hope Creek Nuclear Generating Station, identified a weakness in GE's tracking of errors and changes in the LOCA evaluation models.

Between 1990 and 1995, information sent to the licensee indicated that there had been no

known impact on the calculated peak cladding temperature (PCT). Earlier in 1996, two

impacts had been reported by GE to the licensee and when reviewing the handling of this

information during the audit, three additional impacts not previously reported to the licensee

were discovered, dating back to 1990, 1992, ard 1993. In addition, the audit determined that

GE had not been tracking the cumulative impact of errors and changes on the PCT as

expected by the licensee. The cumulative PCT impact was previously known to be 35 OF

(19 OC); however, on the basis of the errors identified during the audit, the value is now

raised to 100 OF (56 OC) exceeding the 50 'F (28 'C) reporting threshold. The licensee's

recalculated PCT still remains below the ECCS acceptance criteria of 2200 OF (1200 OC).

In a letter to the NRC dated February 17, 1997 [9703060067], GE characterized the licensee- identified weakness as an issue of timeliness of notifications to utilities of errors and changes

in the LOCA evaluation models. Furthermore, notification about changes or errors identified

during the 1990 to 1995 period were provided by GE on an annual basis. Because

notification by GE to boiling-water reactor BWR licensees on individual impacts less than

50 OF (28 OC) were not provided as they occurred, the BWR licensees did not have the

required information to fully comply with the requirements of 10 CFR 50.46 [specifically the

requirement to report within 30 days a cumulative PCT impact greater than 50 OF (28 OC)].

IN 97-15 April 4, 1907 Discussion

Although the LOCA analyses are performed by the fuel vendors, licensees are responsible for

compliance with the regulations related to the LOCA analysis, that is, 10 CFR 50.46(a).

Section 50.46(a)(1)(i) requires licensees to calculate ECCS cooling performance with an

acceptable evaluation model. The staff's recent interactions with the licensees using the

SPC's LBLOCA methodology (the review experience of the SPC LOCA evaluation model

changes) and the Hope Creek QA audit indicate that licensees may not be closely monitoring

the work of their respective fuel vendors. When the error in the 1986 model was discovered

and when SPC changed the TOODEE2 code in 1991, the resulting changes in the PCT were, in some cases, significant, and the responsible licensees were not aware of the significant

changes. "Significant" is defined in 10 CFR 50.46(a)(3)(i) as follows: "a significant change or

error is one which results in a calculated peak fuel cladding temperature different by more

than 500 F from the temperature calculated for the limiting transient using the last acceptable

model, or is a cumulation of changes and errors such that the sum of the absolute

magnitudes of the respective temperature changes is greater than 50 OF."

Licensees may not be performing adequate assessments of errors when they are aware of

them. Furthermore, licensees' audits of SPC's evaluation model changes appear to have

been ineffective in identifying the technical inadequacy of the changes. It should be noted

that 10 CFR 50.46 allows fuel vendors or licensees to make evaluation model changes

without the staffs prior approval; however, the licensees are responsible for identifying any

deficiencies in the change process and reporting them to the NRC staff accordingly. In

addition, the licensee determines whether the changes are significant.

It also appears that licensees may not be monitoring the cumulative effect of the evaluation

model changes. In a given year, the impact of the evaluation model change may be less

than 50 'F (28 OC) on the limiting PCT calculated with the last acceptable model and hence

the change is not significant. But the impact of the evaluation model changes over several

years together can exceed 50 OF (28 OC) and, therefore, will be reportable as significant.

Section 50.46 places the responsibility for the reporting of evaluation model changes on the

limiting PCT calculated with the last acceptable model on the licensees. Some licensees

have apparently considered that the annual notifications sent by the fuel vendor are sufficient

to meet the requirements under 10 CFR 50.46(a)(3)(ii). Specifically, "the applicant or

licensee shall report the nature of the change or error and its estimated effect on the limiting

ECCS analysis to the Commission at least annually as specified in §50.4. If the change or

error is significant, the applicant or licensee shall provide this report within 30 days...." The

notifications submitted by the fuel vendors will not satisfy these reporting requirements;

however, licensees are allowed to refer to the vendor's annual notifications. As stated in

10 CFR Part 50, Appendix B, Section VII, "The effectiveness of the control of quality by

contractors and subcontractors shall be assessed by the applicant or designee at intervals

consistent with the importance, complexity, and quantity of the product or services."

IN 97-15 April 4, 1997 In summary, licensees are reminded that to meet the ECCS acceptance criteria their

responsibilities include:

(1) Section 50.46(a)(1)(i) requires licensees to calculate ECCS cooling performance with an

acceptable evaluation model.

(2) Section 50.46(a)(3)(ii) requires licensees to report changes and/or errors and their

estimated effects on the limiting ECCS analysis to the Commission at least annually, and if the change or error is significant, the licensee shall provide this report within

30 days.

(3) Individual licensees are responsible to assess effectiveness of the control of quality of

ECCS evaluation models provided by the vendors as required by Part 50, Appendix B.

Meaningful technical audits may be necessary to meet Appendix B.

This information notice requires no specific action or written response. If you have any

questions about the information in this notice, please contact one of the technical contacts

listed below or the appropriate Office of Nuclear Reactor Regulation (NRR) project manager.

Thomas T. Martin, Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical contacts: George Thomas, NRR Joseph L. Staudenmeier, NRR

(301) 415-1814 (301) 415-2869 E-mail: gxt@nrc.gov E-mail: jils4@nrc.gov

Eric Benner, NRR

(301) 415-1171 E-mail: ejbl@nrc.gov

Attachment: List of Recently Issued NRC lnformation Notice

of nz3>t PIe 41 i- e

Attachment

IN 97-15 April 4, 1997 LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES

Information Date of

Notice No. Subject Issuance Issued to

97-14 Assessment of Spent 03/28/97 All holders of OLs

Fuel Pool Cooling or CPs for nuclear

power reactors

97-13 Deficient Conditions 03/24/97 All holders of OLs

Associated with Pro- or CPs for nuclear

tective Coatings at power reactors

,Juclear Power Plants

97-12 Potential Armature 03/24/97 All holders of OLs

Binding in General or CPs for nuclear

Electric Type HGA power reactors

Relays

92-27, Thermally Induced 03/21/97 All holders of OLs

Supp. 1 Accelerated Aging or CPs for nuclear

and Failure of ITE/ power reactors

Gould A.C. Relays

Used in Safety-Related

Applications

97-11 Cement Erosion from 03/21/97 All holders of OLs

Containment Subfounda- or CPs for nuclear

tions at Nuclear Power power reactors

Plants

97-10 Liner Plate Corrosion 03/13/97 All holders of OLs

in Concrete Containments or CPs for power

reactors

97-09 Inadequate Main Steam 03/12/97 All holders of OLs

Safety Valve (MSSV) or CPs for nuclear

Setpoints and Perform- power reactors

ance Issues Associated

with Long MSSV Inlet

Piping

OL = Operating License

CP = Construction Permit

IN 97-15 April 4, 1997 In summary, licensees are reminded that to meet the ECCS acceptance criteria their

responsibilities include:

(1) Section 50.46(a)(1)(i) requires licensees to calculate ECCS cooling performance with an

acceptable evaluation model.

(2) Section 50.46(a)(3)(ii) requires licensees to report changes and/or errors and their

estimated effects on the limiting ECCS analysis to the Commission at least annually, and if the change or error is significant, the licensee shall provide this report within

30 days.

(3) Individual licensees are responsible to assess effectiveness of the control of quality of

ECCS evaluation models provided by the vendors as required by Part 50, Appendix B.

Meaningful technical audits may be necessary to meet Appendix B.

This information notice requires no specific action or written response. If you have any

questions about the information in this notice, please contact one of the technical contacts

listed below or the appropriate Office of Nuclear Reactor Regulation (NRR) project manager.

original signed by T.R. Quay

Thomas T. Martin, Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical contacts: George Thomas, NRR Joseph L. Staudenmeier, NRR

(301) 415-1814 (301) 415-2869 E-mail: gxt@nrc.gov E-mail: jls4@nrc.gov

Eric Benner, NRR

(301) 415-1171 E-mail: ejbl@nrc.gov

Attachment: List of Recently Issued NRC Information Notices

Tech Editor has reviewed and concurred on 12/18/96 DOCUMENT NAME: 97-15.IN

OFC TECH C:SXRB:DSSA C:PECB:DRPM D:DRPM

CONTACT

S

NAME EBenner JLyons* AEChaffee* TTMartin

GThomas*

JStaudenmeier

DATE 1/14197 3/07/97 03/21/97 313V97 OFFICIAL RECORD COPY]

.NU IN97-xx

March, 1997 In summary, licensees are reminded that to meet the ECCS acceptance criteria their

responsibilities include:

(1) Section 50.46(a)(1)(i) requires licensees to calculate ECCS cooling performance with an

acceptable evaluation model.

(2) Section 50.46(a)(3)(ii) requires licensees to report changes and/or errors and their

estimated effects on the limiting ECCS analysis to the Commission at least annually, and if the change or error is significant, the licensee shall provide this report within

30 days.

(3) Individual licensees are responsible to assess effectiveness of the control of quality of

ECCS evaluation models provided by the vendors as required by Part 50, Appendix B.

Meaningful technical audits may be necessary to meet Appendix B.

This information notice requires no specific action or written response. If you have any

questions about the information in this notice, please contact one of the technical contacts

listed below or the appropriate Office of Nuclear Reactor Regulation (NRR) project manager.

Thomas T. Martin, Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical contacts: George Thomas, NRR Joseph L. Staudenmeier, NRR

(301) 415-1814 (301) 415-2869 E-mail: gxt@nrc.gov E-mail: jls4@nrc.gov

Eric Benner, NRR

(301) 415-1171 E-mail: ejbl@nrc.gov

Attachment: List of Recently Issued NRC Information Notices

DOCUMENT NAME: G:1SSK2%IN5046.RV2 OFC TECH C:SXRB:DSSA C:PECB:DRPM D:DRPM

CONTACT

S

NAME EBenner JLyons* AEChaffee TTMartin

GThomas*

JStaudenmeDer Ae3 _______

DATE I1/1 4/97 13/07/97 3 7 1'5/-497 LUHIUIAL Kht;UKU UUIFYj 4t~)(-l

vreeu&64J

vea %f 6tlt o Ceene ne4, Aj6A. hr

71ay

Co vn rvnseQtf ctv're cea AV 12'o6. )vDek 4 dateA

0 )67) 9i-7 Faceton 4 9X3e26o>)

IN 97-xx

March , 1997 In summary, licensees are reminded that to meet the ECCS acceptance criteria their

responsibilities include:

(1) Section 50.46(a)(1)(i) requires licensees to calculate ECCS cooling performance with an

acceptable evaluation model.

(2) Section 50.46(a)(3)(ii) requires licensees to report changes and/or errors and their

estimated effects on the limiting ECCS analysis to the Commission at least annually, and if the change or error is significant, the licensee shall provide this report within

30 days.

(3) Individual licensees are responsible to assess effectiveness of the control of quality of

ECCS evaluation models provided by the vendors as required by Part 50, Appendix B.

Meaningful technical audits may be necessary to meet Appendix B.

This information notice requires no specific action or written response. If you have any

questions about the information in this notice, please contact one of the technical contacts

listed below or the appropriate Office of Nuclear Reactor Regulation (NRR) project manager.

Thomas T. Martin, Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical contacts: George Thomas, NRR Joseph L. Staudenmeier, NRR

(301) 415-1814 (301) 415-2869 E-mail: gxt~nrc.gov E-mail: jls4@nrc.gov

Eric Benner, NRR

(301) 415-1171, E-mail: ejbl@nrc.gov

Attachment: List of Recently Issued NRC Information Notices

DOCUMENT NAME: G:XSSK2XIN5046.RV2 OFC TECH C:SXRB:DSSA C:PECB:DRPM D:DRPM

CONTACT

S

NAME EBennei l1 T1Lyons* AEChaffee TTMartin

GThomas

JStaudenmeier

DATE 1/14/97 3/07/97 //97 1/97 OFFICIAL RECORD COPY] V

mu;

K- 1\-J

IN 97-xx

February , 1997 In summary, licensees are reminded that to meet the ECCS acceptance criteria their

responsibilities include:

(1) Section 50.46(a)(1)(i) requires licensees to calculate ECCS cooling performance with an

acceptable evaluation model.

(2) Section 50.46(a)(3)(ii) requires licensees to report changes andlor errors and their

estimated effects on the limiting ECCS analysis to the Commission at least annually, and if the change or error is significant, the licensee shall provide this report within 30

days.

(3) Individual licensees are responsible to assess effectiveness of the control of quality of

ECCS evaluation models provided by the vendors as required by Part 50, Appendix B.

Meaningful technical audits may be necessary to meet Appendix B.

This information notice requires no specific action or written response. If you have any

questions about the information in this notice, please contact one of the technical contacts

listed below or the appropriate Office of Nuclear Reactor Regulation (NRR) project manager.

Thomas T. Martin, Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical contacts: George Thomas, NRR Joseph L. Staudenmeier, NRR

(301) 415-1814 (301) 415-2869 E-mail: gxt@nrc.gov E-mail: jis4@nrc.gov

Stephen Koenick, NRR

(301) 415-2841 E-mail: ssk2@nrc.gov

Attachment: List of Recently Issued NRC Information Notices

DOCUMENT NAME: G:\SSK2\IN5046.RV2 T

OFC TECH I

CONTACT

S

NAME SKoenick S$¶k

GThomaser

JStaudenmeier

DATE 1/14/97 UFFICIAL RECORD COPY]