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

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555 January 3, 1992 NRC INFORMATION NOTICE 92-02: RELAP5/M003 COMPUTER CODE ERROR ASSOCIATED

WITH THE CONSERVATION OF ENERGY'EQUATION

Addressees

All holders of operating licenses or construction permits for nuclear power

reactors.

Purpose

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

to alert addressees of an error in the RELAP5/MOD3 computer'code associated

with the conservation of energy equation. The computer codes in the RELAP5 Series are general purpose, thermal hydraulic system codes used to simulate the

response of systems such as the reactor coolant system (RCS) to transients and

accidents. 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

On November 25, 1991, Northeast Utilities forwarded the enclosed 10 CFR Part 21 initial notification to the NRC Operations Center, regarding an error in the

RELAP5/M003 simulation of the response of the Haddam Neck Plant terry turbine

room 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 the

error on the evaluation of the nuclear steam supply system (NSSS) response to a

loss-of-coolant accident (LOCA) and steam line break has been determined to be

negligible. Appropriate corrections in the code are the responsibility of the

Idaho National Engineering Laboratory (INEL).

Codes in the RELAP5 Series are not intended to be used as containment analysis

codes. Containment analysis specific codes exist for that purpose. The

primary purpose of the RELAP5 codes is analysis of the response of the NSSS

to accident and transient conditions.

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IN 92-02 January 3, l991 This Information notice requires no specific action or written response. If

please contact the

you have any questions about the information in this notice, Reactor

technical contact listed below or the appropriate Office of Nuclear

Regulation (KRR) project manager.

'harles E. Rossi, fire~ctor

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical contact: Nancy Campbell, NRR

(301) 504-2836 Attachments:

1. Northeast Utilities 10 CFR Part 21 Notification

2. List of Recently Issued NRC Information Notices

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Attachnrent 1 IN 92-02 January 3, 1992 hrn. Con#Wcu t

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Nov. 25, 1991

NRC Operations Center

Pax. #(301) 492-8187 SUBSTAMMIL SAPET1Y-HAZARD- IOC:R21 The purpose of this facsimile Is to inform the NRC that on November 25, 1991, at

1605 hours0.0186 days <br />0.446 hours <br />0.00265 weeks <br />6.107025e-4 months <br />, J.F. Opeka, Executive Vice President of Northeast Utilities (NtM)

determined that a substantial safety hazard (SSW) exiStL

During an in-house engineering evaluation of the response of the Haddam Neck

Plant Terry Turbine room to a postulated steam line break, an error was discovered

In the RELAP5/MOD3 simulation. It was determined that the codt was not

conserving energy, and thereby had significantly under predicted the temperature the In

the Terry Turbine room. Had the simulation been accepted, the EEQ profile for

room would have been non-onservative by approximately 100' F

rhe RELAPS series of computer codes are general purpose, thermal hydraulic

systems codes which are used to simulate the response of systes such a the RCS of to

transients and accidents. The codes are written to solve the equations

conservation 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 control

volumes connected by junctions and solving the conservation equations

simultaneously In each volume and Junction uwing a finite difference numerical

scheme. The error appears to be associated with the conservation of energy equation.

While the error in determining environmental conditions can be significant, line the

impact of the error on evaluations of the NSSS response to LOCA and steam

break has been determined to be negligible. NU has made a tentative correction to Its

version of RELAP5/MOD3. A permanent correction of the error will be made to

other NU codes, which are based on RELAP5, when the Idaho National Engineering

Laboratory (INEL) provides the appropriate corrections. The impact of the error on

licensing calculations will be formally assessed and reported via 10CFRS0.46, if

necessary.

According to 10CFRZ1.21(c)(3) i. written notification to the NRC will be forthcoming

within 30 days.

If you have -any questions regarding this matter pleae call Bryan W. Cook at (203)

665.3718.

.ryCook

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Attachment 2 IN 92-02 January 3, 1992

_ LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES

Information Date of

Notice No. Subject Issuance Issued to

92-01 Cable Damage Caused by 01/03/92 All holders of OLs or CPs

Inadequate Cable Installa- for nuclear power reactors

tion Procedures and Controls

91-87 Hydrogen Embrittlement of 12/27/91 All holders of OLs or CPs

Raychem Cryofit Couplings for nuclear power reactors

91-86 New Reporting Requirements 12/27/91 All licensees authorized

for Contamination Events at to use byproduct materials

Medical Facilities for human use.

(10 CFR 30.50)

91-85 Potential Failures of 12/26/91 All holders of OLs or CPs

Thermostatic Control Valves for nuclear power reactors

for Diesel Generator Jacket

Cooling Water

- :1-84 Problems with Criticality 12/26/91 All Nuclear Regulatory

Alarm Components/Systems Commission (NRC) fuel

cycle licensees, interim

spent fuel storage licens- ees, and critical mass

licensees.

91-83 Solenoid-Operated Valve 12/20/91 All holders of OLs or CPs

Failures Resulted in for nuclear power reactors

Turbine Overspeed

91-18, High-Energy Piping Failures 12/18/91 All holders of OLs or CPs

Supp. 1 Caused by Wall Thinning for nuclear power reactors

91-82 Problems with Diaphragms 12/18/91 All holders of OLs or CPs

in Safety-Related Tanks for nuclear power reactors

91-81 Switchyard Problems that 12/16/91 All holders of OLs or CPs

Contribute to Loss of for nuclear power reactors

Offsite Power

= Operating License

= Construction Permit

19-

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