ML20063M713

Responds to IE Bulletin 80-05, Vacuum Condition Resulting in Damage to Chemical Vol Control Sys (CVCS) Holdup Tanks. Tanks Found Not Susceptible to Problems Described in Bulletin.Response Supersedes Util

ML20063M713
Person / Time
Site:	North Anna
Issue date:	08/26/1982
From:	Spencer W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
REF-SSINS-6820 497, IEB-80-05, IEB-80-5, NUDOCS 8209160026
Download: ML20063M713 (3)

Text

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t VIHOINIA ELECTHIC AND l'OWHM COM PANY H ac n w o nn, V NOINIA 2 0 2 Cal 1srn 2 AB: 3/

Wana ma C.Menacan v-. e........ MIS S 8 E Mr. James P. O'Reilly, Director Serial No. 497 Regional Administrator PSE&C/TAE:btw U.S. Nuclear Regulatory Corsaission Region II 101 Marietta Street, Suite 3100 Docket No. 50-404 Atlanta, Geonjia 30303

Dear Mr. O'Reilly:

IE BULLETIN 80-05 VACulH CONDITION RESULTING IN DAMAGE TO CVCS HOLDUP TANKS NORTH ANNA UNIT 3 On October 15, 1979, the Virginia Electric and Power Company announced that it was undertaking a feasibility study of North Anna Units 3 and 4 i During this time, all work on IE Bulletins was deferred, pending the outcome of the study, since one of the studies objectivos was to detenaine

if North Anna 3 and 4 should be continued as nuclear units. During this time, we mceived IE Bulletin 80-05, dated March 10, 1980. A letter Serial No. 267, dated March 28, 1980, was sent to the Commission stating that review of this bulletin was suspended until the completion of the j feasibility study.

i Upon completion of the study, it was detenained that North Anna 4 would be cancelled and North Anna 3 continued as a nuclear unit. As a result, we have resumed that analysis of IE Bulletins and offer the following msponse to the IE Bulletin 80-05:

IE Bulletin 80-05, " Vacuum Condition Resulting in Damage to Chemical Volume Control System (CVCS) Holdup Tanks," identifies potential release of radioactive gases af ter tank failure due to vacuum conditions. The following are the results of our systems review with regard to the problem reported in the referenced IE Bulletin:

1. List of reviewed systems:

Reactor Coolant Chemical Addition Makeup and Purification Bomn Recovery Hydrogenated Drains Gaseous Waste 8209160026 820826 PDR ADOCK 05000404 G PDR ((//

Vmoma Eucmc Axo Pona Comwy to Mr. O'Reilly 2

2. Technical Justification The msults of this review show that the only tanks confoming to the criteria for examination outlined in 80-05 to be the RC Drain Tank (3RC-TKl) and the Makeup Tank (3MU-TX1). During nomal plant conditions, only these tanks may be valved to contain primary system fluid at low p mssu re. The review also included the Gas Stripper Suge Tank (3BR-TK3), the Hydrogenated Drains Transfer Tank (30G-TKl), and the Waste Gas Surge Drum (3GW-TK2). The Gas Stripper Surge Tank and Waste Gas Surge Drum may, under nomal operating conditions, be valved to contain contaminated gas at low pressure.

The review showed that these tanks are protected from the effects of potentially damaging vacuum conditions. The makeup tank is protected during nomal operation through the interconnection with the plant Hydrogen System.

Self-mgulating Pressure Control Valve PCV-300 is set to maint 2in tank internal hydrogen pressure of 35 psia. Should the tank begin to drain, the evacuated space will be filled with gas through this valve. The hydrogen supply line contains, in addition to PCV-300, The Babcock & Wilcox Company (B&W) supplied valve A0V-22. This valve fails closed on a loss of nomal air to isolate the Makeup Tank contents. This action prevents potential outleakage of the contaminated tank contents. In doing so, however, it also isolates the hydrogen supply line. A single failure, then, of the plant nomal air system, or a single operator action of incorrectly closing A0Y-22, could leave the Makeup Tank susceptible to vacuum conditions. In order to correct this situation, the vacuum breaker RY-312 is provided on the Makeup Tank vent line.

The RC Drain Tank, Gas Stripper Surge Tank, and the Waste Gas Surge Drum are designed to withstand a full internal vacuum. In addition, the RC Drain Tank is supplied with nitrogen gas protective blanket during nomal operation.

The Hydrogenated Drains Transfer Tank, which is currently under design, will be engineered for vacuum protection in accordance with IE Bulletin 80-05.

In surnary, all tanks within the scope of IE Bulletin 80-05 have been reviewed and found to not be susceptible to the problems described in the bulleti n. In each case, the tanks are provided with protection against vacuum and/or designed to withstand a full internal vacuum.

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i v =oina ructmc iso rowr.. cow,*xy to Mr. O'Reilly 3

This letter supersedes letter Serial No. 267 which stated that review '

of IE Bulletin 80-05 was suspended.

i Very truly yours, -

i f 'fr <1 /

! W. Spencer I ,

i cc: Mr. Robert L. Tedesco L Division of Licensing a

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