Information Notice 1982-28, Hydrogen Explosion While Grinding in the Vicinity of Drained and Open Reactor Coolant System

Hydrogen Explosion While Grinding in the Vicinity of Drained and Open Reactor Coolant System

ML070220265
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, Sterling, 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, 05000514, 05000599, 05000000, 05000515, 05000355, 05000502, 05000600, Zimmer, Fort Saint Vrain, Washington Public Power Supply System, Shoreham, Satsop, Trojan, Allens Creek, Atlantic Nuclear Power Plant, Perkins, Cherokee, Clinch River, Skagit, Marble Hill, Black Fox, Hartsville, Phipps Bend, Yellow Creek
Issue date:	07/23/1982
From:	Jordan E NRC/IE
To:
References
IN-82-028 NUDOCS 8204210401
Download: ML070220265 (4)

SSINS No.: 6835 IN 82-28 UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF INSPECTION AND ENFORCEMENT

WASHINGTON, D.C. 20555 July 23, 1982 IE INFORMATION NOTICE NO. 82-28: HYDROGEN EXPLOSION WHILE GRINDING IN THE

VICINITY OF DRAINED AND OPEN REACTOR COOLANT

SYSTEM

Addressees

All nuclear power reactor facilities holding an operating license (OL) or

construction permit (CP).

Purpose

This information notice is provided as a notification of an event that may have

safety significance. It is expected that recipients will review the information

for applicability to their facilities. No specific action or response is

required at this time.

Description of Circumstances

On April 10, 1982, a hydrogen explosion occurred at Unit 1 of Arkansas Nuclear

One wtille maintenance personnel were grinding a recently cut high-prfssure

injection (HPI) pipe, approximately 18 inches from the nozzle connecting the

HPI pipe to the reactor coolant system (RCS) piping. At the time of the

explosion, the RCS was partially drained and the water level in the reactor

coolant piping was just below the HPI nozzle to permit radiography of the

nozzle and subsequent repair. (IE Information Notice No. 82-09 provides

details concerning the cracking problem in HPI piping at Babcock & Wilcox

plants.) The reactor coolant temperature was being maintained at approximately

IOOF by the decay heat removal system, and nitrogen cover gas was being

maintained in the reactor coolant piping. These conditions existed since the

RCS was depressurized and partially drained on March 29, 1982.

At approximately 1240 hours0.0144 days <br />0.344 hours <br />0.00205 weeks <br />4.7182e-4 months <br /> on April 10, 1982, the craftsmen, who were grinding

on the HPI pipe in preparation for welding, observed a bright flash at the

outlet of the HPI line and heard a loud "bang". The craftsman actually per- forming the grinding was physically blown away from the HPI pipe a distance of

about three feet. Personnel in other areas of the Unit I containment building

heard the explosion and felt the resulting concussion and mechanical vibration.

Additionally, some personnel outside of the containment building, including

operat6rs in the Unit I control room reported that they heard the explosion and

felt varying degrees of vibration. Although there were no physical injuries as

a result of this event, it should be mentioned that the craftsman's life was

endangered as he was working on a scaffold that was over 30 feet high.

The most recent RCS measurement of dissolved gas in reactor coolant had been

taken on March 26, 1982, just before commencing the plant cooldown and shutdown.

It indicated 39 standard cc of total gas/liter of coolant. The hydrogen

8ZO42-10401

IN 82-28 July 23, 1982 concentration was 43% of this total. Because the total gas concentration

exceeded the maximum allowed by plant procedures (30 cc/liter) for RCS

depressurization, the RCS was degassed for approximately 14 hours1.62037e-4 days <br />0.00389 hours <br />2.314815e-5 weeks <br />5.327e-6 months <br /> as cooldown

progressed. The total gas concentration was not measured after degassing had

been terminated because the RCS had been depressurized and the sampling method

is effective only when the RCS pressure is greater than several hundred psig.

Atmospheric samples had not been taken to measure hydrogen and oxygen concen- trations in the vicinity of the open HPI pipe. (This had been done at other

Babcock and Wilcox plants which were undergoing nozzle repair.)

The reason for the presence of an explosive concentration of hydrogen is

unknown. It could have been caused by (a) inadequate degassing, (b) failure to

purge the HPI pipe with nitrogen, or (c) failure to temporarily plug the open

HPI pipe.

Subsequent inspection of the affected HPI line, the first upstream check valve

in the HPI line, and the corresponding nozzle and safe-end on the RCS cold leg

indicated no signs of damage as a result of the explosion.

No written response to this information is required. If you need more informa- tion about this matter, please contact the Regional Administrator of the

appropriate NRC Regional Office or this office.

Edward L. Jordan, Director

Division of Engineering and

Quality Assurance

W. Marinelli

301-492-9654 Attachment:

List of Recently Issued IE Information Notices

WPU:JD DEQA: IE DEQA: IE DEQA: IE DEQA: IE D: DEQA: IE

7/20/82 WMarinelli RWoodruff JCunningham RBaer EJordan

5520 7/ /82 7/ /82 7/ /82 7/ /82 7/4ý C/82

IN 82- X ,q"1982 Page 3 of

Atmospheric samples had not been taken to measure hydrogen and oxygen

concentrations in the vicinity of the open HPI pipe. (This had been done at

other Babcock and Wilcox plants which were undergoing nozzle repair).

The reason for the presence of an explosive concentration of hydrogen is

unknown. It could have been caused by (a) inadequate degassing, (b) failure

to purge the HPI pipe with nitrogen, or (c) failure to temporarily plug the

open HPI pipe.

Subsequent inspection of the affected HPI line, the first upstream check valve

in the HPI line, and the corresponding nozzle and safe-end on the RCS cold leg

inditated no signs of damage as a result of the explosion.

No written response to this information is required. if you need more about

this matter, please contact the Regional Administrator of the appropriate

NRC Regional Office.

Sincerely, Edward L. Jordan, Director

Division of Engineering and.

Quality Assurance

Office of Inspection and Enforcement

Technrical Contact: W. Marinelli

301-492-9654 Attachment:

Recently issued IE Information Notices

mkm DEQA:IE DEQA:IE E D D

6/17/82 WMarinelli RWoodruff JCtulingham RBaer

5520 6/1j/82 6 6/ý0W 82 60/82

Attachment

IN 82-28 July 23, 1982 LIST OF RECENTLY ISSUED

IE INFORMATION NOTICES

Information Date of

Notice No. Subject Issue Issued to

82-27 Control of Radiation Levels 7/23/82 All medical

in Unrestricted Areas institutions

Adjacent to Brachytherapy

Patients

82-26 RCIC and HPCI Turbine 7/23/82 All BWR power

Exhaust Check Valve Failures reactor facilities

holding and OL or CP

82-25 Failures of Hiller Actuators 7/22/82 All power reactor

upon Gradual Loss of Air facilities holding

Pressure an OL or CP

82-24 Water Leaking from Uranium 7/20/82 All NRC licensed

Hexafluoride Overpacks enriched uranium

fuel fabrication

plants

81-26, Clarification of Placement 7/20/82 All power reactor

Part 3, of Personnel Monitoring facilities holding

Sup. No. 1 Devices for External an OL or CP

Radiation

82-23 Main Steam Isolation Valve 7/16/82 All BWR power

(MSIV) Leakage reactor facilities

holding an OL or CP

82-22 Failures in Turbine Exhaust 7/9/82 All power reactor

Lines facilities holding

an OL or CP

82-21 Buildup of Enriched Uranium 6/30/82 All uranium and

in Effluent Treatment Tanks plutonium fuel

fabrication

licensees

82-20 Check Valve Problems 6/28/82 All power reactor

facilities holding

an OL or CP

OL = Operating License

CP = Construction Permit