81

RECORD #81,

TITLE: Low Level Radioactive Waste Scaling Factors, 10 CFR Part

61

FICHE: 35369-063

81
SSINS No.: 6835

IN 86-20

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF INSPECTION AND ENFORCEMENT

WASHINGTON, D. C. 20555

March 28, 1986

IE INFORMATION NOTICE NO. 86-20: LOW-LEVEL RADIOACTIVE WASTE SCALING FACTORS,

10 CFR PART. 61

Addressees:

All nuclear power plant facilities and fuel facilities holding an operating

license (OL) or a construction permit (CP).

Purpose:

This notice is provided to alert licensees to a problem in the methodologies

used to determine facility scaling factors for low-level radioactive waste

classification. This notice is intended to assist licensees in properly

determining waste classification scaling factors.

It is expected that recipients will review the information provided for applicability, if appropriate, to their waste classification programs. However,

suggestions contained in this notice do not constitute NRC requirements; therefore, no specific action or written response is required.

Description of Circumstances:

Recent NRC inspections have identified poor correlation between generic

radionuclide concentration data used to classify waste and actual radionuclide

sample data at some nuclear power plants. Similarly, these inspections determined

that some plants with multiple waste streams have been using one set of scaling

factors to classify waste from all their waste streams despite significant

differences (greater than a factor of 10) in radionuclide concentrations. Such

practices may-lead~to significant underestimation of certain radionuclides with

direct health and safety consequences. The practices may also lead to significant

over estimates which limit disposal capacity and increase costs.

Discussion:

Any licensee who transfers radioactive waste to a land disposal facility or to

a licensed waste collector or processor is required by 10 CFR 20.311(d)(1) to

classify the waste according to 10 CFR 61.55. The three low-level waste

classes (A, B, and C) as defined in 10 CFR 61.55(a)(2)-(a)(7) describe the

manner in which the classification is to be computed, based on concentrations

of certain radionuclides within the waste. Recognizing-that some of these

radionuclides may be difficult to routinely measure using counting equipment

normally found at power reactor facilities, 10 CFR 61.55(a)(8) permits use of
IN 86-20

March 28, 1986

Page 2 of 2

indirect methods, such as scaling factors. Such methods can be used to determine

concentrations of difficult-to-measure radionuclides provided there is reasonable

assurance that the indirect methods can be correlated with actual measurements.

On May 11, 1983, the NRC Division of Waste Management forwarded to all licensees

a technical position (TP) paper on waste classification describing procedures

acceptable to the regulatory staff which may be used by licensees to determine

the presence and concentration of radionuclides listed in 10 CFR 61.55. That

position paper is affirmed to represent the current regulatory staff position

on this matter.

Since 10 CFR 61 became effective in January 1984, licensees have had varying

experiences in attempting to develop scaling factors specific to their facility

and waste streams. Initially, the staff exercised flexibility in determining

compliance with 10 CFR 61 and permitted licensees to use generic scaling factors

to determine waste classification, provided that the licensee was actively

developing specific scaling factors for its facility and'waste streams.

The attachment describes problems which have been observed by the NRC relative

to inappropriate methodologies sometimes used by licensees on the application of

waste stream scaling factors and provides guidance to avoid those problems.

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

If you have any questions about this matter, please contact the Regional

Administrator of the appropriate regional office or this office.

't~ra'rd Lordan, Director

Divisio Emergency Preparedness

and Er~ neering Response

Office of Inspection and Enforcement

Technical Contact: A. Grella, IE

(301) 492-7746

Attachments:

1. Discussion of Scaling Factor Methodology Problem

2. List of Recently Issued IE Information Notices
Attachment I

IN 86-20

March 28, 1986

Page 1 of 2

DISCUSSION OF SCALING FACTOR METHODOLOGY PROBLEM

The TP paper states that scaling factors should bedeveloped on a facility and

waste stream specific basis. The staff also considers that in determining

measured or inferred radionuclide concentrations, the concentrations are to be

accurate to within a factor of 10. Scaling factors based on a single set of

detailed sample analysis results are acceptable, provided that there is reasonable assurance as to the representativeness of the samples.

Inspections have indicated that, several licensees have continued to use generic

data, (i.e., data from similar waste streams from several other facilities),

combined with actual plant-sample data to derive facility scaling factors. This

approach was taken because of a limited number of facility waste stream samples.

The difficulty arises when scaling factors derived from the mix of generic and

facility-specific data are under-conservative and differ from the actual facility

samples by generally greater than a factor of 10. Some differences as high as

a factor of 10,000 have been observed, yet some licensees have continued to use

the scaling factors containing generic sample data. Continued use of scaling

factors which produce estimates of radionuclide concentrations that differ from

the most recent actual measurement of that radionuclide concentration by generally

more than a factor of 10 may constitute noncompliance with 10 CFR 61.55(a)(8)

since the reasonable assurance of correlation standard cannot be met. 'When

discrepancies are observed, either the scaling factors need to be adjusted to

agree with the most recent analysis of that waste stream or the waste stream

needs to be resampled, if there is some question as to the validity of the sample

analysis result causing the disagreement. Questions also may arise as to the

correct classification of the waste, if classification based on the most recent

sample analysis would result in a higher classification from that calculated by

using the generic scaling factors.

As a sample analysis history of facility waste streams is compiled, licensees

may. choose to determine new scaling factors based on the most recent sample

analysis resuldt$ or may combine the latest analysis with those previously obtafned

to refine the scaling factors currently in use. Because large differences may

have been caused by changes in plant operating conditions (e.g., increased fuel

leakage, crud burst, etc.), the previous sample analysis results may not be

representative of the waste stream and new scaling factors may need to be

considered.

Inspections also have disclosed questions in licensee identification and

determination of scaling factors for each facility waste stream. Several

licensees have used only one set of scaling factors to determine the classifications of wastes from all of their waste streams. For some licensees this has

resulted in underestimates of selected radionuclide concentrations. However,

the majority of licensees that use only a single set of scaling factors overestimate some of the radionuclide concentrations in the wastes, because the

most conservative ratio for a radionuclide from the various waste stream

samples is chosen as the scaling factor for that radionuclide.
Attachment I

IN 86-20

March 28, 1986

Page 2 of 2

While using scaling factors which underestimate the radionuclide concentrations

is clearly a problem, gross overestimation of the concentrations also is of

concern. To ensure that 10 CFR 61 performance objectives are met, inventory

restrictions may be established at a disposal facility for specific radionuclides

such as Tc-99 or C-14. Because an overestimate in radionuclide inventory

results in a corresponding overestimate in potential environmental releases,

systematic gross overestimates in waste radionuclide concentrations may result

in underutilization of the disposal facility.. This could result in limited

disposal capacity and higher disposal costs. Therefore, licensees may benefit

from identifying individual facility waste streams and determine unique scaling

factors for each. Facilities that have more than one operating unit will

probably need separate scaling factors for each waste stream that is unique to

each operating unit. One set of scaling factors would be appropriate for

waste produced by systems shared by-two or more units.

The following are examples of waste streams that may warrant establishment of

unique scaling factors to classify wastes from those sources:

Pressurized Water Reactor

Primary Purification Filters

Primary Purification Resins

CVCS Evaporator Bottoms

Radwaste Polishing Resins

Secondary System Wastes (filters and resins)

Dry Active Waste

Boiling Water Reactor

Cleanup Filters/Resins

Condensate Polishing Resins

Evaporator Bottoms

Radwaste Ion Exchange Resins

Dry Active-Waste
Attachment 2

IN 86-20

March 28, 1986

LIST OF RECENTLY ISSUED

IE INFORMATION NOTICES

Information Date of

Notice No. Subject Issue Issued to

86-19

86-18

Reactor Coolant Pump Shaft

Failure At Crystal River

NRC On-Scene Response During

A Major Emergency

Update Of Failure Of Automatic Sprinkler System Valves

To Operate

3/21/86

3/26/86

86-17 3/24/86

86-16 Failures To Identify Contain- 3/11/86

ment Leakage Due To Inadequate

Local Testing Of BWR Vacuum

Relief System Valves

86-15

86-14

86-13

86-12

Loss Of Offsite Power Caused

By Problems In Fiber Optics

Systems

PWR Auxiliary Feedwater Pump

Turbine Control Problems

Standby Liquid Control

System Squib Valves Failure

To Fire

Target Rock Two-Stage SRV

Setpoint Drift

Inadequate Service Water

Protection Against Core ,Melt

Frequency

Operation Of Emergency Diesel

Generators

3/10/86

3/10/86

2/21/86

2/25/86

2/25/86

2/24/86

All power reactor

facilities holding

an OL or CP

All power reactor

facilities holding

an OL or CP

All power reactor

facilities holding

an OL or CP

All power reactor

facilities holding

an OL or CP

All power reactor

facilities holding

an OL or CP

All power reactor

facilities holding

an OL or CP

All BWR facilities

holding an OL or CP

All power reactor

facilities holding

an OL or CP

All power reactor

facilities holding

an OL or CP

All power reactor

facilities holding

an OL or CP

86-11

84-69

Sup. 1

.1

'DL =Operating License

CP = Construction Permit