ML20126B182

Special Rept:On 921118,pressurizer PORV 2NC-34 Opened While in Low Pressure Mode,Resulting in Lifting of Valve & Reducing Nc Pressure to Below PORV Setpoint.Improved Procedure Guidance Developed & Addl Training Conducted

ML20126B182
Person / Time
Site:	Catawba
Issue date:	12/17/1992
From:	Tuckman M DUKE POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9212220002
Download: ML20126B182 (3)

Text

a ll l 1

Duke Ibuer Company kl.S rt win f'

Cata:rba Nucleur Generation Department bice President 4800 Concord Road {803)MIJ205 0thce fi'rk, SC29745 (S&3)S31J4?6fu DUKEPOWER l

l December 17,1992 i

, U. S. Nuclear Regulatory Commission ATrN: Document Control Desk

Washington, DC 20555 l

Subject:

Catawba Nuclear Station, Unit 2

- Docket No. 50-414 1- Special Report Inadvertent Lifting of Pressurizer Power Operated Relief Valve 2NC-34 4

Pursuant to Technical Specification 3.4.9.3 Action (d), find attached'a Special Report concerning the inadvertent lifting of Unit 2 Pressurizer Power Operated Relief Valve 2NC-

34 while in low pressure mode, i

l Very truly yours, s ,

a hwt-1 M. S. Tuckman CRIJSR121792.POR '

xc: S. D. Ebneter Regional Administrator, Region 11 R. E. Martin, ONRR W 'T. Orders Senior Resident Inspector 2:i.~ 123 ~

9212220002 921217 DR_-ADOCK-0 44 pg.

- + ~ - 'lr

0 SPECIAL REPORT CATAWBA NUCLEAR STATION, UNIT 2 Inadvertent Lifting of Pressurizer Power Operated Relief Valve 2NC-34 While in Low Pressure Mode On November 18,1992 at 0902, the Unit 2 Pressurizer Power Operated Relief Valve (PORV) 2NC-34 opened while in low pressure mode. The lift pressure for the PORV in low pressure mode is 400 psig.

A shutdown was in progress to repair the Unit 2 D (2D) Reactor Coolant (NC) pump #1 seal. The unit was in Mode 5, at approximately 300 psig and 140*F, with NC pumps 2A

, and 2C in service. While in the pmcess of taking the Pressurizer solid for Hydrogen Peroxide addition, a detennination was made that solid operation may not be required.

Pressurizer level increase was stopped at an indicated level of approximately 80%, while the need to take the pressurizer solid was being evaluated. 80% is the cold calibmtion

pressurizer level which translates to approximately 95% actual level. Charging and letdown were thought to be balanced to maintain the 80% pressurizer level; however, NC charging flow continued to be slightly greater than NC letdown flow. During the next several hours, pressurizer level slowly increased to an indicated level of approximately 85%, at which time the pressurizer was solid. Once the pressurizer was solid, the small charging flow offset quickly mised NC pn

ssure to the PORV setpoint of 400 psig. The PORV opened, reducing NC pressure to below the PORV setpoint, and then reclosed. The operator recognized the pressure inen:ase through the alarms received and immediately 1

reduced charging flow and increased letdown flow. The plant was then stabilized at approximately 300 psig.

1 To prevent reoccurrence, the following corrective actions are planned:

1. Improve procedure guidance for the approach to solid operations.

2. Conduct additional training on the approach to solid operations.

3. Evaluate the adequacy of the infonnation available to the operators for converting indicated pressurizer level to actual level at low NC tempemtures.

v U. S. Nuclear Regulatory Commission December 17,1992 Page 2 bxc: R. C. Futrell R. L. Gill W. R. McCollum C. R. Lewis K. E. Nicholson J. W. Glenn S. S. Cooper W. O. Reeside (PIR 2-C'2-0824)

Group File: 801.01 Master File: 801.01 C

. _ _ _ _ _ _ . _ _ _ _ _ _ _ . _ _ _ _ _ _ _ _ _ _ . _ _ _ . _ _ _ .