ML20062H118

Forwards IE Info Notice 79-07,Rupture of Radwaste Tanks

ML20062H118
Person / Time
Site:	Crystal River
Issue date:	03/26/1979
From:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
To:	Stewart W FLORIDA POWER CORP.
References
NUDOCS 7905020404
Download: ML20062H118 (1)

Text

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f UNITED STATES

1. M*&g NUCLEAR REGULATORY COMMIS$10N

, e o,,

[ n REG 10N il I .

101 M ARIETTA STREET,N.W.

I ATLANTA. GEORGIA 30303 1.,.....'/ MAR 2 61979 e

In ly Refer To:

I:JP 0-302 ,

Florida Power Corporation Attn: Mr. W. P. Stewart, Director Power Production P. O. Box 14042, Mail Stop C-4 St. Petersburg, Florida 33733 s

Gentlemen:

The enclosed IE Information Notice No. 79-07 is forwarded to you for information. No specific action is requested and no written response is required. If you desire additional information regarding this matter, please contact this office.

Sincerely, K

L  %\i ~

James P. O'Reilly 4 Director

Enclosure:

IE Information Notice No. 79-07 cc w/ enc 1:

G. P. Beatty, Jr.

l Nuclear Plant Manager l

l P. O. Box 1228 ,

I Crystal River, Florida 32629 l

l 790502C4'Of f

UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCIMENT WASHINGTON, D.C. 20555 March 26, 1979 IE Information Notice No. 79-07 RUPIURE OF RADWASTE TANKS Description of Circumstances:

In November, 1977 a radvaste tank ruptured at the Millstone Nuclear Power Station. Two problems led to the tank failure. First, the tank vent, which was intended to relieve excessive pressure in the radvaste tank, had been plugged by accumulated solidified concentrates. Second, r corrosion had weakened the capability of the radvaste tank to withstand pressure. Individually, or in combination, these problems were causa-tive factors in the rupture of the radvaste tank due to overpressurization.

The Licensee Event Report states that an aerated vaste concentrates tank vas overpressurized and ruptured. The tank contained radvaste evapo-rator concentrates with a 10-12 percent boric acid concentration. These concentrates, when cooled to ambient temperatures, formed a solid crystaline structure. Apparently, concentrate had entered the vent line by previous tank overflows or purging of air through the tank so that a solid buildup occurred in the vent line. This buildup eventually led to a flov blockage in the vent line. The licensee, in an attempt to blev out or clear a radwaste pipe, applied 100 PSI air pressure to the tank.

The tank was designed for 15 PSI and the plugged vent could not relieve pressure. Therefore, the tank overpressurized and ruptured.

This tank had a history of corrosion problems such that the corrosion

' probably caused some weakness which contributed to the rupture. The tank was constructed of type 30L stainless steel. The plant was a sea-coast site such that significant amounts of chlorides were present in the aerated vaste syste= and, consequently, in the vaste concentrate l tank. The presence of significant amounts of chlorides, coupled with residual velding stresses in the type 30k stainless steel, resulted in chloride stress corrosion.

March 26, 1979 IE Information Notice No. 79-07 Page 2 of 2 Since radvaste tanks of this type are used at most power reactors, the Also, potential may exist for similar events at other power reactors.

such events can be avoided by proper procedures and periodic examination if personnel are aware of the problem. In addition, proper considera-tion of design features (e.g., materials selection and vent designs) can minimize the probability of such an event. Prevention of such events vill minimize the possibility of personal injury, in-plant contamination, releases of radioactivity, and occupational radiation exposure resulting from the repair and clean-up operations.

No specific action or written response to this Information Notice is required. If you require additional information regarding this subject, conthet the Director of the appropriate NRC Regional Office.

Enclosure:

List of IE Information Notices Issued in 1979 9

6

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IE Information Notice No. 79-07 March 26, 1979 LISTING OF IE INFORMATION NOTICES ISSUD IN 1979 Sub, ject Date Issued To Information Notice No. Issued Bergen-Paterson Hydraulic 2/2/79 All power reactor 79-01 facilities with an Shock and Sway Arrestor OL or a CP Attempted Extortion - 2/2/79 All Fuel Facilities 79-02 Low Enriched Uranium

1. Limitorque valve Geared 2/9/79 All power reactor 79-03 facilities with an Limit Svitch Lubricant OL or a CP 2/16/79 All power reactor 79-04 Degradation of Engineered facilities with an Safety Features OL or a CP Use of Improper Materials 3/21/79 All power reactor 79-05 facilities with an in Safety-Related Components OL or CP Stress Analysis of 3/23/79 All Holders of 79-06 Reactor OL or CP Safety-Related Piping J

Enclosure

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