Information Notice 1990-08, KR-85 Hazards from Decayed Fuel

KR-85 Hazards from Decayed Fuel
	ML031130307
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, 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, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant, Crane
Issue date:	02/01/1990
From:	Rossi C; Office of Nuclear Reactor Regulation
To:	;
References
	IN-90-008, NUDOCS 9001260198
	Download: ML031130307 (7)
	v • d • e

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555

February 1. 1990

NRC INFORMATION NOTICE NO. 90-08: KR-85 HAZARDS FROM DECAYED FUEL

Addressees

All holders of operating licenses or construction permits for nuclear power

reactors and holders of licenses for permanently shutdown facilities with

fuel on site.

Purpose

This information notice alerts addressees to potential problems resulting from

the .accidental release of Kr-85 from decayed fuel. It is expected that reci

pients will review the Information for applicability to their facilities and

consider actions, as appropriate, to avoid similar problems. However, sugges- tions co'ntained in this information notice do not constitute NRC 'requirements;

therefore, no specific action or written response is required.

Desripionof Circumstances:

During the licensing reviews for the Oconee independent spent fuel storage

Installation,, and in the decommissioning of the La Crosse and Dresden Unit 1 power reactors, the NRC staff analyzed the radiological hazards associated

.with the gases In decayed spent fuel. The age of the nuclear power industry

and the lack of a permanent repository for spent fuel have resulted in the

accumulation of decayed'spent fuel.* Decayed spent fuel is manipulated after

long shutdowns of operating reactors, during spent fuel pool re-racking, during

mo~vement to alternate reactor sites or independent spent fuel storage instal- lations, and during decommissioning. Analysis of hypothetical accidents

involving decayed spent fuel has focused attention on potential difficulties

that'could be associated with the exposure of onsi1te personnel to an accidental

release of Kr-85.

IKr-85 is a noble gas fission product that is present in the

gaps between the fuel pellets and the cladding. It has a 10.76-year half-life, and, as a result of the considerably shorter half-lveso ital l te

gaseous fission products (1-129 being the exception, but in low abundance),,

Kr-85 becomes Increasingly the dominant nuclide in the accident source term

for gap releases as decay times increase. After 2 weeks of decay, Kr-85 is

a significant nuclide in the source term, and after 190 days of decay, it is

the predominant gaseous nuclide for a gap release. The unusual decay character- istics of K~r-85 give cause for focusing attention on the onsite consequences

of a gap release from decayed fuel.

,-

9001260198

40--

IN 90-08 February 1, 1990 Discussion:

Kr-85 emits beta radiation with a maximum energy of 0.67 MeY for 99.6 percent of

the decays and 0.51 MeV gamma radiation. for 0.4 percent of the decays. Conse- quently, direkt exposure to this gas would result in a dose to the skin approxi- mately 100 times the whole-body dose. Analysis of the relative consequences (in

terms of radiological doses) of a cask-drop accident as a function of decay time

of the fuel is illustrated in Figure 1. In the event of a serious accident

involving decayed spent fuel, protective actions would be needed for personnel

on site, while offsite doses (assuming an exclusion area radius of 1 mile from

the plant site) would be well below the Environmental Protection Agency's

Protective Action Guides. Accordingly, it is important to be able to properly

survey and monitor for Kr-85, and to assess the skin dose to workers who could

be exposed to Kr-85 in the event of an accident with decayed spent fuel.

Licensees may wish to reevaluate whether Emergency Action Levels specified in

the emergency plan and procedures governing decayed fuel-handling, activities

appropriately focus on concern for onsite workers and Kr-85 releases in areas'

where decayed spent fuel accidents could occur, for example, the'spent fuel

pool working floor. Furthermore, licensees may wish to determine if emergency

plans and corresponding implementing procedures address the means for limiting

radiological exposures of onsite personnel who are in other areas of the plant.

Among other things, moving onsite personnel away from the plume and shutting

off building air intakes downwind from the source may be appropriate.

This information notice requires no specific action or written response. If you

have any questions about the information in this notice, please contact one of

the technical contacts listed below or the appropriate NRR project manager.

Charles E. Ross

Di ctor

Division'of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical Contacts: Charles S. Hinson, NRR

(301) 492-3142

Robert A. Meck, RES

(301) 492-3737 Attachments:

1. Figure 1, Dose Consequences of a

Spent Fuel Drop Accident

2. List of Recently Issued NRC Information Notices

N

N.

. Atitchment 1 IN 90-08 I

February 1, 1990 DOSE CONSEQUENCES

OF

A SPENT

FUEL

DROP ACCIDENT-

103

102

ArMR SHUTDOWN

Figure 1

Attachment 2

in 90-08

February 1, 1990

Page I of I

LIST OF RECENTLT ISSUED

NRC INFORMATION NOTICES

}stanntina

V

_

Notice No.

BJ-23, Supp. 2

.

. I

m . .

-

90-O7*

90-06

90-05

-

90-04

90-03

90-02

90-01

_- ---

89-90 -_

89-89 Subject

Potential for Gas Binding

.of Ngh-Prussura Ssfety

InJection Pumps During a

Loss-of-Coolant Accident

New information Rgarding

Insulation Materal1

Performance and Debris

Blockage of PWR Contain.

ment Sumps

Potential for Loss of

Shutdown Cooling While

at

Low Reactor Coolant

Levels

Inter-Systes Discharge of

Reactor Coolant

Cracking of the Upper Shell- to-TransitIon Cone 6irth

Welds in Steam Generators

Malfunction of Borg-Warner

Bolted Sonnet Check Valves

Caused by Failure of the

Swing Arm

Potential Degradation of

Secondary Containsent

Importance of Proper

Response to Self-Identifled

Violations by Licensees

Pressurizr-Safty

l

Lift Setpoint Shift.

Eient Notificatin

Workshests

Date or

Issuance

1/31/90

1/30/90

Issued to

All holders of OLs

or CPs for PWRs.

All holders of OLts

or CPs for nuclear

power reactors.

1/29/90

All holders of OLs

or CPs for nuclear

power reactors.

1/29/90

1/26/90

1/23/90

All holders of OLs

or CPs for nuclear

power reactors.

All holders'of OLs

or CPs for Westinghouse- designed and Coatustion

Engineering-designed

nuclear power reactors.

All holders of OLs

or CPs for nuclear

power reactors.

1/22/90

All holders of OLs.

or CPa for BWRs.

1/12/90

All holders of NRC

materials licenses.

12t/28/81 All

olbders or OLs

or CPs for Prs.

12/26/839

All holders of OLs

or CPs for nuclear

power reactors:'

OL

Operating License

CP

Construction Permit

UNITED STATES

NUCLEAR REGULATORY COMMISSION

WASHINGTON, D.C. 20555'!

OFFICIAL BUSINESS

PENALTY FOR PRIVATE USE. UOO

IPOSTAGE It

FEES PAIDI

jusNAcj

- 11 - -1 IN 90-08 February 1, 1990 Discussion:

Kr-85 emits beta radiation with a maximum energy of 0.67 MeY for 99.6 percent of

the decays and 0.51 MeY gamma radiation for 0.4 percent of the decays. Conse- quently, direct exposure to this gas would result in a dose to the skin approxi- nately 100 times the whole-body dose.

Analysis of the relative consequences (in

terms of radiological doses) of a cask-drop accident as a function of decay time

of the fuel is illustrated in Figure 1. In the event of a serious accident

involving decayed spent fuel, protective actions would be needed for personnel

on site, while offsite doses (assuming an exclusion area radius of 1 mile from

the plant site) would be well below the Environmental Protection Agency's

Protective Action Guides. Accordingly, it is important to be able to properly

survey and monitor for Kr-85, and to assess the skin dose to workers who could

be exposed to Kr-85 in the event of an accident with decayed spent fuel.

Licensees may wish to reevaluate whether Emergency Action Levels specified in

the emergency plan and procedures governing decayed fuel-handling activities

appropriately focus on concern for onsite workers and Kr-85 releases in areas

where decayed spent fuel accidents could occur, for example, the spent fuel