Information Notice 1979-07, Rupture of Radwaste Tanks

Rupture of Radwaste Tanks

ML031180125
Person / Time
Site:	Waterford, 05000000
Issue date:	03/26/1979
From:	NRC/IE
To:
References
IN-79-007, NUDOCS 7904120337
Download: ML031180125 (3)

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF INSPECTION AND ENFORCEMENT

WASHINGTON, D.C. 20555 March 26, 1979 IE Information Notice No. 79-07

Description of Circumstances

Millstone Nuclear

In November, 1977 a radwaste tank ruptured at the First, the tank

Power Station. Two problems led to the tank failure.

pressure in the radwaste

vent, which was intended to relieve excessive concentrates. Second, tank, had been plugged by accumulated solidified

of the radwaste tank to withstand

corrosion had weakened the capability these problems were causa- pressure. Individually, or in combination, to overpressurization.

tank due

tive factors in the rupture of the radwaste

waste concentrates tank

The Licensee Event Report states that an aerated radwaste evapo- was overpressurized and ruptured. The tank contained

boric acid concentration. These

rator concentrates with a 10-12 percent formed a solid

concentrates, when cooled to ambient temperatures, entered the vent line

crystaline structure. Apparently, concentrate had the tank so that a

by previous tank overflows or purging of air through eventually led to

buildup

solid buildup occurred in the vent line. This in an attempt to blow

a flow blockage in the vent line. The licensee, pressure to the tank.

out or clear a radwaste pipe, applied 100 PSI air

vent could not relieve

The tank was designed for 15 PSI and the pluggedand ruptured.

pressure. Therefore, the tank overpressurized

that the corrosion

This tank had a history of corrosion problems such the rupture. The

to

probably caused some weakness which contributed The plant was a sea- tank was constructed of type 304 stainless steel.

were present in

coast site such that significant amounts of chlorides

the waste concentrate

the aerated waste system and, consequently, in coupled with

tank. The presence of significant amounts of chlorides, steel, resulted in

residual welding stresses in the type 304 stainless

chloride stress corrosion.

power reactors, the

Since radwaste tanks of this type are used at most power reactors. Also, potential may exist for similar events at other

and periodic examination

such events can be avoided by proper procedures

o*(3*

IE Information Notice No. 79-07 March 26, 1979 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

will 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, contact the Director of the appropriate NRC Regional Office.

IE Information Notice No. 79-07 March 26, 1979 LISTING OF IE INFORMATION NOTICES

ISSUED IN 1979 Information Subject Date Issued To

Notice No. Issued

79-01 Bergen-Paterson Hydraulic 2/2/79 All power reactor

Shock and Sway Arrestor facilities with an

OL or a CP

79-02 Attempted Extortion - 2/2/79 All Fuel Facilities

Low Enriched Uranium

79-03 Limitorque Valve Geared 2/9/79 All power reactor

Limit Switch Lubricant facilities with an

OL or a CP

79-04 Degradation of 2/16/79 All power reactor

Engineered facilities with an

Safety Features OL or a CP

79-05 Use of Improper Materials 3/21/79 All power reactor

in Safety-Related Components facilities with an

OL or CP

79-06 Stress Analysis of 3/23/79 All Holders of

Safety-Related Piping Reactor OL or CP

79-07 Rupture of Radwaste Tanks 3/26/79 All power reactor

facilities with an

OL or CP