Information Notice 1987-13, Potential for High Radiation Fields Following Loss of Water from Fuel Pool

Potential for High Radiation Fields Following Loss of Water from Fuel Pool
	ML031140520
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, 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, 05000000, Zimmer, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant, Skagit, Marble Hill
Issue date:	02/24/1987
From:	Jordan E; NRC/IE
To:	;
References
	IN-87-013, NUDOCS 8702190620
	Download: ML031140520 (4)
	v • d • e

SSINS No.: 6835 IN 87-13 UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF INSPECTION AND ENFORCEMENT

WASHINGTON, D.C. 20555 February 24, 1987 IE INFORMATION NOTICE NO. 87-13: POTENTIAL FOR HIGH RADIATION FIELDS

FOLLOWING LOSS OF WATER FROM FUEL POOL

Addressees

All holders of a nuclear power reactor operating license (OL) or a construction

permit (CP) except Fort St. Vrain.

Purpose

This information notice is to alert addressees of the potential for high

radiation fields following the inadvertent loss of water from the spent fuel

pool or transfer canal. Recipients are expected to review the information for

applicability to their facilities and consider actions, if appropriate, to

preclude similar problems occurring at their facilities. However, suggestions

contained in this information notice do not constitute NRC requirements;

therefore, no specific action or written response is required.

Description of Circumstances

On December 2 and 3, 1986, the Hatch nuclear power plant lost 141,000 gallons

of water from the spent fuel pool because of a leak from pneumatic seals in the

transfer canal between Units 1 and 2. The redundant pneumatic seals leaked

because of a single failure. A valve in the single air supply line to the

seals was mistakenly closed. Although water level dropped about 5 feet and low

level alarms in the spent fuel pool worked, the leak was not specifically

identified for several hours because a leak detection device was valved out and

none of the seals were instrumented to alarm on loss of air pressure.

Analysis by the licensee after the event has shown that, if water had been

completely lost from the transfer canal, radiation fields would be high enough

that remedial measures may be difficult. High radiation fields would be

present because irradiated control blades are stored on short hanger rods

clipped over the side of the spent fuel pool. A control blade's roller bearing

is typically made of cobalt-rich stellite which, when activated, has radiation

levels of 8,000 to 10,000 R/hr on contact. Some of the control blades would be

completely uncovered if the water level dropped to the bottom of the transfer

canal. This drop in water level would result in general area radiation levels

of about 100 R/hr at the edge of the spent fuel pool and 1 R/hr 6 feet from the

edge of the pool. About 2 feet of water would remain over the top of the spent

fuel at the minimum level resulting from draining via the transfer canal; so, there was no likelihood of fuel damage because of fuel uncovery.

IN 87- February , 1987 Discussion:

The potential for this general type of event was discussed in IE Information

Notice No. 84-93, "Potential for Loss of Water from the Refueling Cavity,"

issued on December 14, 1984 and IE Bulletin No. 84-03, "Refueling Cavity Water

Seal," issued on August 24, 1984. The transfer canal between the Hatch units

is an unusual design that illustrates yet another way a single failure resulted

in substantial loss of water from the spent fuel pool.

Although recipients of IN 84-93 and IEB 84-03 may have evaluated the potential

uncovering of spent fuel, recipients may not have fully evaluated the potential

for high radiation fields because of the potential uncovering of short hangers

or other short fixtures holding irradiated material such as used control rods

or neutron detectors.

Since the event, concern has been raised about the design of the leak detection

system for the seals. The leak detection system consists of a level switch

that is piped between the first and second pneumatic seals to detect water

leakage that gets past the first seal. The NRC is currently evaluating this

design to determine whether water would flow past the leak detector if all

seals failed and thus fail to detect the leak.

As corrective measures, the licensee has separated the air supply to the

transfer canal seals and the air supply to the inner and outer gates between

the transfer canal and the spent fuel pools and is studying other changes to

assure greater reliability. The licensee also is shipping the used control

rods in the spent fuel pool off the site.

No specific action or written response is required by this information notice.

If you have questions about this matter, please contact the Regional Adminis- trator of the appropriate NRC regional office or this office.

Edward L. Jordan, Director

Division of Emergency Preparedness

and Engineering Response

Office of Inspection and Enforcement

Technical Contacts: Eric Weiss, IE

(301) 492-9005 Floyd Cantrell, Region II

(404) 331-5534 Attachment: List of Recently Issued IE Information Notices

by phone

RCroteau for

Region II

SEE PREVIOUS CONCURRENCE FCantrel

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Attachment 1 IN 87-13 February 24, 1987 LIST OF RECENTLY ISSUED

IE INFORMATION NOTICES

Information Date of

Notice No. Subject Issue Issued to

86-106 Sup. 1 Feedwater Line Break 2/13/87 All power reactor

facilities holding

an OL or CP

87-12 Potential Problems With 2/13/87 All power reactor

Metal Clad Circuit Breakers, facilities holding

General Electric Type AKF-2-25 an OL or CP

87-11 Enclosure of Vital Equipment 2/13/87 All power reactor

Within Designated Vital facilities holding

Areas an OL or CP

87-10 Potential for Water Hammer 2/11/87 All BWR facilities

During Restart of Residual holding an OL or CP

Heat Removal Pumps

87-09 Emergency Diesel Generator 2/5/87 All power reactor

Room Cooling Design facilities holding

Deficiency an OL or CP

87-08 Degraded Motor Leads in 2/4/87 All power reactor

Limitorque CD Motor facilities holding

Operators an OL or CP

87-07 Quality Control of Onsite 2/3/87 All power reactor

Dewatering/Solidification facilities holding

Operations by Outside an OL or CP

Contractors

87-06 Loss of Suction to Low- 1/30/87 All power reactor

Pressure Service Water facilities holding

System Pumps Resulting From an OL or CP

Loss of Siphon

87-05 Miswiring in a Westinghouse 2/2/87 All Westinghouse

Rod Control System power reactor