Information Notice 1992-02, Relap5/Mod3 Computer Code Error Associated with the Conservation of Energy Equation

Relap5/Mod3 Computer Code Error Associated with the Conservation of Energy Equation

ML031200771
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, 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, Crane
Issue date:	01/03/1992
Revision:	0
From:	Rossi C E Office of Nuclear Reactor Regulation
To:
References
IN-92-002, NUDOCS 9112270227
Download: ML031200771 (4)

UNITED STATESNUCLEAR REGULATORY COMMISSIONOFFICE OF NUCLEAR REACTOR REGULATIONWASHINGTON, D.C. 20555January 3, 1992NRC INFORMATION NOTICE 92-02: RELAP5/M003 COMPUTER CODE ERROR ASSOCIATEDWITH THE CONSERVATION OF ENERGY'EQUATION

Addressees

All holders of operating licenses or construction permits for nuclear powerreactors.

Purpose

The U.S. Nuclear Regulatory Commission (NRC) is issuing this information noticeto alert addressees of an error in the RELAP5/MOD3 computer'code associatedwith the conservation of energy equation. The computer codes in the RELAP5Series are general purpose, thermal hydraulic system codes used to simulate theresponse of systems such as the reactor coolant system (RCS) to transients andaccidents. It is expected that recipients will review the information forapplicability to their facilities and consider actions, as appropriate, toavoid similar problems. However, suggestions contained in this informationnotice are not NRC requirements; therefore, no specific action or writtenresponse is required.

Description of Circumstances

On November 25, 1991, Northeast Utilities forwarded the enclosed 10 CFR Part 21initial notification to the NRC Operations Center, regarding an error in theRELAP5/M003 simulation of the response of the Haddam Neck Plant terry turbineroom to a postulated steam line break. The equipment environmental qualifica-tion (EEQ) profile for the room would have been nonconservative by approxi-mately 100OF had the simulation been accepted. Although the error in deter-mining the environmental conditions could be significant, the effect of theerror on the evaluation of the nuclear steam supply system (NSSS) response to aloss-of-coolant accident (LOCA) and steam line break has been determined to benegligible. Appropriate corrections in the code are the responsibility of theIdaho National Engineering Laboratory (INEL).Codes in the RELAP5 Series are not intended to be used as containment analysiscodes. Containment analysis specific codes exist for that purpose. Theprimary purpose of the RELAP5 codes is analysis of the response of the NSSSto accident and transient conditions.9112270227 IL r; -O0'1'=' II AI I I I I 11 I I -oil' III III -W, F I IN 92-02January 3, l991 This Information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please contact thetechnical contact listed below or the appropriate Office of Nuclear ReactorRegulation (KRR) project manager.'harles E. Rossi, fire~ctorDivision of Operational Events AssessmentOffice of Nuclear Reactor RegulationTechnical contact: Nancy Campbell, NRR(301) 504-2836

Attachments:

1. Northeast Utilities 10 CFR Part 21 Notification2. List of Recently Issued NRC Information Notices=INN I I III 11-111, NEI I 102111 r11MM M 11 11 111M1111'

Attachnrent 1IN 92-02January 3, 1992 JORMIEAT UILITU 0n Offt

• loidn Stfmt. hrn. Con#Wcu tP.O. 0ox m_ _ O~AKWORD. CONNECTICUT 06141N.=_ WbWC _ 12M) US4=Nov. 25, 1991NRC Operations CenterPax. #(301) 492-8187SUBSTAMMIL SAPET1Y-HAZARD- IOC:R21The purpose of this facsimile Is to inform the NRC that on November 25, 1991, at1605 hours, J.F. Opeka, Executive Vice President of Northeast Utilities (NtM)determined that a substantial safety hazard (SSW) exiStLDuring an in-house engineering evaluation of the response of the Haddam NeckPlant Terry Turbine room to a postulated steam line break, an error was discoveredIn the RELAP5/MOD3 simulation. It was determined that the codt was notconserving energy, and thereby had significantly under predicted the temperature Inthe Terry Turbine room. Had the simulation been accepted, the EEQ profile for theroom would have been non-onservative by approximately 100' Frhe RELAPS series of computer codes are general purpose, thermal hydraulicsystems codes which are used to simulate the response of systes such a the RCS totransients and accidents. The codes are written to solve the equations ofconservation of mass, energy and momentum within the system being modeled.The code solves for the system response by modeling the system as a series of controlvolumes connected by junctions and solving the conservation equationssimultaneously In each volume and Junction uwing a finite difference numericalscheme. The error appears to be associated with the conservation of energy equation.While the error in determining environmental conditions can be significant, theimpact of the error on evaluations of the NSSS response to LOCA and steam linebreak has been determined to be negligible. NU has made a tentative correction to Itsversion of RELAP5/MOD3. A permanent correction of the error will be made toother NU codes, which are based on RELAP5, when the Idaho National EngineeringLaboratory (INEL) provides the appropriate corrections. The impact of the error onlicensing calculations will be formally assessed and reported via 10CFRS0.46, ifnecessary.According to 10CFRZ1.21(c)(3) i. written notification to the NRC will be forthcomingwithin 30 days.If you have -any questions regarding this matter pleae call Bryan W. Cook at (203)665.3718..ry Cook____A 0aAttachment 2IN 92-02January 3, 1992 _LIST OF RECENTLY ISSUEDNRC INFORMATION NOTICESInformation Date ofNotice No. Subject Issuance Issued to92-0191-8791-8691-85-:1-8491-8391-18,Supp. 191-8291-81Cable Damage Caused byInadequate Cable Installa-tion Procedures and ControlsHydrogen Embrittlement ofRaychem Cryofit CouplingsNew Reporting Requirementsfor Contamination Events atMedical Facilities(10 CFR 30.50)Potential Failures ofThermostatic Control Valvesfor Diesel Generator JacketCooling WaterProblems with CriticalityAlarm Components/SystemsSolenoid-Operated ValveFailures Resulted inTurbine OverspeedHigh-Energy Piping FailuresCaused by Wall ThinningProblems with Diaphragmsin Safety-Related TanksSwitchyard Problems thatContribute to Loss ofOffsite Power01/03/9212/27/9112/27/9112/26/9112/26/9112/20/9112/18/9112/18/9112/16/91All holders of OLs or CPsfor nuclear power reactorsAll holders of OLs or CPsfor nuclear power reactorsAll licensees authorizedto use byproduct materialsfor human use.All holders of OLs or CPsfor nuclear power reactorsAll Nuclear RegulatoryCommission (NRC) fuelcycle licensees, interimspent fuel storage licens-ees, and critical masslicensees.All holders of OLs or CPsfor nuclear power reactorsAll holders of OLs or CPsfor nuclear power reactorsAll holders of OLs or CPsfor nuclear power reactorsAll holders of OLs or CPsfor nuclear power reactors= Operating License= Construction Permit21 0 M E Mil 1 1 I 1 111.a lI' 19-