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Public Version - NRC Training on Chrms Calibration (1).pptx
	ML21327A271
Person / Time
Issue date:	11/23/2021
From:	; Office of Nuclear Reactor Regulation
To:	;
	Garry S
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2021 NRC Staff Training Calibration of Containment & Dry Well Ion Chamber High Range Rad Monitors

{CHRMs) 1

Disclaimer

This was a training course in 2021 for NRC inspection staff. This training is intended to provide inspectors with basic knowledge of the calibration process.

This training is not an instruction manual for licensees to use in the calibration of radiation monitors.

This training does not establish any new NRC position on calibration of radiation monitoring equipment.

The training material should not be used by licensees to demonstrate compliance with NRC requirements.

NRC does not endorse or make any recommendations on selection of any vendor radiation monitoring e

2

Table of Contents

Module 1 (Slide 4) - Introduction & Background

Module 2 (Slide 9) - Regulatory Basis

Module 3 (Slide 68) - CHRMs Equipment

Module 4 (Slide 97) - CHRMs Calibration Process

Module 5 (Slide 182) - Inspector Preparation & Experiences

Module 6 (Slide 198) - Licensee Calibration Procedures

Module 7 (Slide 223) - References

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Module I Introduction

Background

Training Objectives

Provide inspector training on calibration of CHRMs

Provide the regulatory basis for calibration requirements

Describe calibration methods for the:

- Primary calibration of the original "Design" detector

- Calibration of "Production" (replica) detectors

- "Transfer" calibration using "Field Calibrator"

- "In Situ" (in-plant) calibration

'1 5

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Detector Terminology

Prototype (design) ion chamber/detector

- The original design detector that is fully-tested by the manufacturer/vendor

- Was used to establish a generic calibration constant of approximately (lE-11 :7:;)

Production (replica) detectors

- Production detectors are replicas of the "Design" detector made for sale to power plants

- Manufacturers made several production detectors ("'200 -

"'300 detectors were sold to plants)

Field Calibrators - calibration jigs 6

LND Ion Chambers

Ion chambers are made commercially and sold to vendors

Some ion chambers have an energy response (flattening) shield

Ion chambers are tested for dose-rate linearity to rv 10,000,000 R/hr

Ion chambers are energy response tested from rv 80 keV to 3 MeV 7

Typical CHRM Ion Chamber

--- 3 inch diameter --- 8 inch length 8

Module 2 Regulatory Basis

Regulatory Basis

NRC Regulations

- General Design Criteria 64 - Accident Monitoring

- 10 CFR 50.34 - Plant Design Criteria

- 10 CFR 20.lS0l(c) - Calibration

- Tech Specs on CHRMs and Post Accident Monitoring

Regulatory Guides

NUREGs

HPPOS 10

General Design Criterion 64 Monitoring Radioactivity Releases

Provide radioactivity monitoring, including postulated accidents for:

- containment atmosphere

- effluent discharges

- (offsite) plant environs 11 I

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NRC Regulations

10 CFR 50.34 (f) "Additional TMl-related requirements"

- paragraph 50.34{f){2){xvii) - Provide for containment radiation intensity (high level), and noble gas effluents, and continuous sampling of iodines and particulates in gaseous effluents

10 CFR 20.lS0l(c) calibration

- Instruments and equipment must be calibrated periodically for the radiation measured 12

Example: Tech Specs NUREG-1431 3.3 INSTRUMENTATION 3.3.3 Post Accident Monitoring (PAM) Instrumentation LCO 3.3.3 The PAM instrumentation for each Function in Table 3.3.3-1 shall be OPjERABLE.

SURVEILLANCE FREQUENCY SR 3.3.3. 1 Perform CHANNEL CHECK for each required [ 31 days instrumentation channel hat is normally energ.ized.

OR In accordance with the Suiveillance Frequency Control Program ]

13

Tech Specs Table, 3 .3.3- age 1 of 1 Post Accident lloni oring I strun1entatio FUNCTIO REQUIRED CH ELS ACTIO 0 .1

10. Containment Area Radiation (High Range) 2 F 5.6.5 Post Accident ;Monitor~ng Report When a report is requrred by Condition B or F of LCO 3.3.P] **Post Accident Monirtoring (PAI\ Ins rumentatron , a report shall be* sub il~tted withrn the 1

following: 14 days. The report shall outline the preplanned alternate method of monitorinp the cat se of he ino erability and the plans and schedule for restoring' he instrun1entation channels of the Function to OPERABLE status.

RTM-96 and RASCAL NUREG-1940 (2012) Rev. 4

NRC Response Technical Manual (RTM) - 96

NUREG-1940, RASCAL, Section 1.2.4

Provides estimated core damage as a function of containment radiation levels (see next slides)

Containment/ Drywell Dose Rates (per RTM-96}

CHRMs will detect RCS leakage into containment

Approximate (nominal) thresholds values for CHRMs:

- ,v 1 R/h Minimum steady state value during normal operations

- ,v 200 R/hr Approx. max TMl-2 reading (even with loss of RCS and core melt)

- ,v 1 R/hr - 10,000 R/hr Some fuel failure with loss of RCS barrier

- ,v 10,000 R/hr - 100,000 R/hr Loss of fuel cladding & loss of RCS barrier

- ,v 100,000 R/hr - 10,000,000 R/hr 16 Core melt with loss of RCS barrier

TMl-2 CHRMs Readings (NUREG-0600)

DOME MON ITOR H P - R -214 1,000 R/hr ~o t e : The res p onse o t h is ~ n1 t or s h ou1d 3 / 213/79 b e interpreted on l y as a relative i ndica -

t i on o f rad i a *t1on level in conta1 nment .

The actual leve l ; s not s llo wn b eca.u se the at t e :nua *ion provide d by the detector s h i e l d was not ac c ounted fo r .

100 R/hr Control Room alarm at 8 R/hr A l a rm 18,000 mA'/ Hr) -

1 R/hr 101 L---- -....a........_ _ _ ___...__ __ _ __.__ _ _ ___.__ _ __ __.___ __ __,___ _ __ -.J 17 0625 0635 0645 0 6 55 0705 07 15 0 725 0735

PWR Containment RTM-96/ NUREG-1940 1e+6 100,000 ~ 1e+S R/hr -ci:

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TMl-2, ...

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i Plant conditions

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mR/hr

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s 1e+5

§ I::; =

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ANSI Standards

ANSI calibration standards are not NRC requirements, but are good practices

5 broad categories of ANSI standards

- Portable survey instruments

- Fixed instrumentation

- Air sampling

- Effluent monitoring

- Emergency instrumentation 21 *l U.S.NRC

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Partial List of Current ANSI Standards

ANSI Nl3.10 -1974 - Instrumentation for Monitoring Routine Effluents (replaced by ANSI N42.18-1980}

~NSI N323-1978 - Calibration of Portable Instruments

~NSI N320-1979 - Emergency Instrumentation (R1993, draft 2019)

ANSI N323D-2002 - Installed routine instrumentation

ANSI N42.18-2004 - Effluent Monitoring {replaced by N42.54)

ANSI N323C-2009 - All air monitoring instruments

ANSI N13.1-2011- Air Sampling {1969, 1999, 2011, draft 2021)

ANSI N42.54-2018- Instrumentation for Monitoring Airborne RAM

{combines N42.17B, N42.18, N42.30 and N323C)

ANSI N42.33-2019 - Portable Exposure Rate Meters 22 *l U.S.NRC f>roft'( 'fing lh,plr ,,,,,/ tht* r,,, ,,ro11mr11I

Trans£er Instrument

ANSI terminology uses the term a "Transfer lnstrument and "Transfer Standard 11 11

A Transfer Instrument is basically called a "Field Calibrator 11 or a "Calibration Jig/'

Field Calibrator is used to expose the detector in a fixed geometry to a standard radioactive source i

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ANSI N323-1978 Portable Instruments Section 5.1 Calibration Standards

- ANSI N323-1978 generally applies to portable instrumentation

- ANSI N323-1978 principles are also applicable to fixed instrumentation (such as CHRMs)

Transfer lnstruinent ANSI N323-1978 Portable Instruments

Section 5.1 Transfer calibrations

Instruments should be calibrated against a national or derived source

Section 5.2 Transfer (Field Calibrator) Precision

(Geometry) positioning errors should be less than+ 2%

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ANSI N320-1978 Elllergency lnstrulllentation

Section 5. 7 Overall System Accuracy~ 40%

- Accuracy - how close the measurement is to the right answer (conventionally true value)

Overall system accuracy shall be within +/- 40%

Note: "Calibration" criteria should not be confused with the "design" criteria The factor of 2 in RG 1.97 is a design criteria for detector response from 60 keV to 3 MeV 26

IEEE Std 497 -2017 Criteria for accident monitoring instrumentation

Annex A - Accident monitoring instrument channel accuracy

Logarithmic scales - required accuracy+/- 50%

ANSI N320-1978 Einergency lnstruinentation

Section 5.7, Overall System "Precision"

- Precision (repeatability) - repetitive measurements give "similar" answers within one or two standard deviations

- Small changes in calibration geometry can make large changes in detector output and a decrease in prec1s1on 28

Exposure Geometry

There are two different exposure geometries, (each has a specific purpose)

1. Initial calibration is a uniform exposure geometry (similar to the exposure geometry in containment or dry well),

used to establish the CHRMs calibration constant

The calibration constant is used in the microprocessor to convert output (amps) into a dose rate R/hr

2. Plant calibration "check"

1. Geometry is a non-uniform exposure geometry,

2. Calibration check is used to make sure the CHRMs are working properly 29

Exposure Geometry

1. Uniform exposure geometry occurs when measuring actual dose rates in containment/drywell during an accident

2. Non-uniform exposure geometry occurs during in-plant calibrations, when there is a short distance between source and detector

- Short distances are needed in order to get on-scale "high" dose rates from 1- 10 R/hr

- Non-uniform geometry is acceptable for use in a Field Calibrator 30

Uniform Radiation Field ANSI N323-1978 Portable Instruments

Section 6.1 - Uniform radiation field

- The distance between a source and the radioactive source must be 7 times the largest dimension of detector

An ion chamber detector with an 8-inch length would require the point source to be located 4.7 feet away!!

The dose rate throughout the detector is then 99.5% of dose rate at the detector center

However, the dose rate at a distance of 7X would be small, unless the source activity is very high 31

Uniform Exposure Geometry

NCRP-112, §§ 4.3.3

- radiation field (for determining the initial calibration constant) should be uniform over the cross-section or depth of the detector

- Note: CHRM manufacturer performs the original calibrations using uniform broad beam geometry, anips in units of /

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Non-Uniform Exposure Geometry

"Field Calibrators" do not provide uniform dose rates over the volume of the detectoti

iThat is acceptable because

- the purpose is to determine if the CHRM is working properly by comparison to original Transfer calibration

- The CHRM is measuring a reproducible, repeatable, non-uniform radiation field

- he idea is to ensure the CHRM is working the same as it was first calibrated by the vendor/manufacturer 33

NCRP-112, §2.7.1 Common Causes of Error (Uncertainty)

Erroneous measurement in the Field Calibrator

- Geometry errors - i.e., source-to-detector measurement (especially at small distances)

- Inability to read a distance scale or an instrument scale

- Parallax reading error

Half-life decay corrections i

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"Overall" Uncertainty NCRP-112, §2.7.1

The likely uncertainty which combines statistical treatments and systemic error (NCRP-58 (1985)

NRC notes:

- Geometry/ positioning errors (using home-made field calibrators) is the most likely source of error and errors can be large

- Statistical (counting) error is insignificant with high dose rates

- Instrument display/ reading error 35

Example: Uncertainty/Error Analysis

Typical uncertainty

Field Calibrator accuracy + 5%

Pico-amp measuring error + 2%

Detector precision + 20%

Nuclide/ Isotope accuracy + 20%

Total uncertainty= SQRT of sum of squares

= 5 2 + 22 + 20 2 + 20 2 = 829%

SQRT of 829% = 28.8% total uncertaint~

~NSI N320-1980 criteria +/- 40%

IEEE 497-2017 criteria is+ 50%

36

NIST Traceability

NIST/NBS Measurement Assurance Program (MAP) certification process

- Supplier submits a calibrated source to NIST/NBS, or

- NIST/NBS provides calibrated blind test sources

Typical Condenser R meter Used for NIST Traceability r -M ETER 100 ,

. . . with a chamber for YOUR application For h enty year'<. the Cond e nser r-mct r with modification and rcfin men ts ha be n a cepted a a condary tandard for at.: ui*ate measurement of x-radiation.

38

ANSI N42.22-1995 (R2002)

NIST Traceable Sources

Manufacturer's can get qualified by NIST, and then establish NIST-traceable source activities

ANSI Std N42.22 provides a description of the criteria necessary for manufacturers (or any organization) to get qualified (to establish traceability of radionuclides to NIST) 39

ANSI N42.22 Definitions

Section 3.3 Manufacturer - any commercial organization approved by NIST (through a MAP) to produce or distribute certified NIST-traceable sources

Section 3.4 MAP -A NIST "Measurement Assurance Program" allowing manufacturers to produce certified sources

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ANSI N42.22 Definitions

3.4 Measurement Assurance Program (MAP)

- manufacturers must demonstrate their capability to produce accurate standardized sources by participation in a NIST

3.8 NIST traceability

- the process of relating the accuracy of sources to national physical standards 41

ANSI N42.22 Definitions

Section 3.6 NIST source verification

- Process of verifying that manufacturers are qualified to create NIST traceable sources

- process of qualifying manufacturers to create NIST traceable sources

Section 3. 7 Product verification - manufacturer submits a (calibrated) source to NIST for verification

Section 4.7 and 4.9 NIST Traceable Certificates - are provided by manufacturers to its customers

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ANSI N42.22 NIST

- Section 6. Measurement Assurance Program (MAP)

Requires vendors/manufacturers to perform annual verification tests for each calibration techniques and instrument type

Manufacturers analyze blind samples supplied by NIST 43

NIST-traceable Sources

Provides data on Radionuclide, Activity, Date of Assay, Dose rate

ifhe dose rate given on source certificates is not useful information for CHRMs calibrations; i.e.,

- Certificates provide dose rate at a "point" (narrow beam geometry)

- Detectors have volume, CHRMs have a ""3-inch diameter, 8-inch length

- At close distances, a point source, placed 2 inches from an 8" detector does not provide a uniform radiation field

- Makes a big difference in the detector output 44

TMl-2 Accident

During TMl-2 accident, NRC and plant staff did not know:

- status of reactor core and threat level to the public

- what to recommend for Protective Action Recommendations

NRC Immediate Response

- Accident started at 4 am, March 28, 1979

- NRC staff arrived at 10 am, set up in conference room with glass window looking into Control Room (no Technical Support Center or EOF}

- Control Room air monitor alarmed, Operators & Chemists wore respirators

- Chemists pulled samples;

90 R/hr sample line valve

400 R/hr at 1 foot on a 300 ml RCS sample

2 or 3 overexposures (of quarterly limits) 45

TMI-2 Report on Radiological Aspects

NRC staff (l&E) prepared a comprehensive technical report on radiological aspects

- Contained in NUREG-0600 (ML090050311)

- Radiological Aspects in NUREG-0600

- Summary - pgs 13 - 21 (pdf pgs 31- 39)

- Appendix II "Details"

Document pages pg II -1 to 11-E-6)

Pdf pgs 436 - 779 46

Post-TMI Requirements

NRC issued new recommendations and requirements:

- NUREG-0578 {July 1979) - Post-TM I Short Term Recommendations

{Item 2.1.8) {ML090060030)

- NUREG-0660 {May 1980) - NRC Action Plan, Vol. 1 and 2

{ML072470526 and ML072470524)

- NUREG-0737 {Nov 1980) - Clarification of NRC Action Plan

{ML051400209}

- New equipment requirements included:

Containment High Range Monitors (CHRMs)

Post Accident Sampling Systems (PASS) 1 47

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NRC's Elllergency Response Data Systelll (ERDS)

10 CFR 50, Appendix E, Section VI

NUREG-1394, ERDS Implementation (ML080790038)

- A real-time electronic data link between licensee's computer systems and NRC Ops Center

- Software provided by NRC to collect accident data

- Data on 4 categories of plant conditions

Rx core and coolant systems

Rx containment

Radioactivity Release Rates

Met tower data 48 *~' U.S.NRC Protatlrrg /h,plr ,11,r/ tht* F m 1rm1mo1t

ERDS Data NUREG-1394

2. ERDS Information 2.1 EROS Des ign Concept The ystem *elect d to fu lfill the data colle-ction needs of the i the Emergency Response Data System (ERDS). The Emergency, esponse Data System concept is a direct electronic 1

transmission of se1ected parameters (Figures 1 and 2) rom the electronic data systems that are currently installed at licensee facilities.,

Radiation Monitoring System Reactor Coolant Radioactivity Level Primary Containment Radiation Level Condenser *Off Gas Radiation Level Effluent Radiation Monitor Pro ess Radiation Levels Meteorological Wind Speed

\Vi nd Direction Atmospheric Stability 49

Post-TMI Requirements

NRC - new recommendations and requirements:

- NUREG-0578 (July 1979) - Post-TM I Short Term Recommendations

{Item 2.1.8) (ML090060030)

- NUREG-0660 (May 1980) - NRC Action Plan, Vol. 1 and 2 (ML072470526 and ML072470524)

- NUREG-0737 (Nov 1980) - Clarification of NRC Action Plan (ML051400209)

- New equipment requirements included:

Containment High Range Monitors (CHRMs}

Post Accident Sampling Systems (PASS) 50

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NRC Coininunications following TMI-2 accident

NRC Letters, Commitments, Orders

The September 13, 1979, letter (ML073520999) to licensees gave operating plants 30 days to review and make commitments to meet these NUREG-0578 requirements or to take exception and provide a justification

The October 30, 1979, letter (ML031320403) gave operating licensees, when not in complete agreement with the post-TM I action plans, 15 days to figure out how to comply or take exception to the action items, and to respond to the NRC

Licensees made commitments to NRC

NRC followed with Orders issued to each licensee to implement their commitments

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NUREGs and Letters to Licensees

September and October 1979 letters instructed licensees to review the NRC staff recommendations in NUREG-0578 (dated July 1979) and to make commitments to the NRC within 30 days to implement the NUREG-0578 items

May 1980 - NUREG-0578 items had not yet been reviewed and approved by the NRC Commission. Subsequently, NUREG-0578 items were modified and expanded by NRC staff to a comprehensive list, which we re published as NUREG-0660.

November 1980 - NUREG-0660 items were reviewed by the Commission and a subset of items were approved by the Commission and published in NUREG-0737.

NUREG-0737 included Item 11.F.1 with expanded guidance on the design of monitoring and calibration requirements.

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NUREG-0737 (NRC ADAMS No. ML051400209)

Item 11.F.1 Additional Radiation Monitoring Requirements

NRC Letters, Commitments, Orders

The September 13, 1979, letter (ML073520999) to licensees gave operating plants 30 days to review and make commitments to meet these NUREG-0578 requirements or to take exception and provide a justification

The October 30, 1979, letter (ML031320403) gave operating licensees, when not in complete agreement with the post-TM I action plans, 15 days to figure out how to comply or take exception to the action items, and to respond to the NRC

Licensees made commitments to NRC

NRC followed with Orders issued to licensees to implement their commitments 55

NUREG-0737 Item 11.F.l 11.F.l ADDITIONAL ACCIDENT-MONITORING INSTRUMENTATION Introduction Item II.F.l of NUREG-0660 contains the following sub~arts:

(1) Noble gas effluent radiological monitor; (2) Provisions for continuous sampling of plant effluents for postaccident releases of radioactive *iodines and particulates and onsite laboratory capabilities (this requirement was inadvertentl y omitted from NUREG-0660; see Attachment 2 that follows, for position);

(3) Containment high-range radiation monitor; (4) Containment pressure monitor; (5) Containment water level monitor; and (6) Containment hydrogen concentration monitor.

NUREG-0578 provided the basic requirements associated with items (1) through (3) above. letters issued to all operating nuclear power plants dated September 13, 1979 and October 30, 1979 provided clarification of staff require-ments associated with items (1) through (6) above. Attachments 1 through 6 present the NRC osition on these matters.

56

NUREG-0737 Table 11.F.l-3 TABLE I I. F. 1 - 3 CONTAINMENT HIGH-RANGE RADIATION MONITOR REQUIREMENT The capabil '.ty to detect and measure the radiation level withi the reactor cont ainment during and follow i ng an acc i dent.

RANGE 1 rad/hr to 10 8 rads/hr (beta and gamma} or alternatively 1 R/hr to 10 7 R/hr (gamma on l y) .

RESPONSE 60 keV to 3 MeV photons, with linear energy response

+ 20%) for photons of 0.1 MeV to 3 MeV . Instruments must be accurate enough to provide usable i nformatio .

REDUNDANT A minimum of two physically separated monitors (i.e . ,

monitoring wide l y separated spaces within containment) .

DESIGN AND Category 1 instruments as descr*bed i n Append i x A except QUA Li !CATION as listed below.

SPECIAL In s i tu ca l ibration by electronic signa l substitution is CALIBRATION acceptable for all range decades above OR/hr. In situ calibration for at least one decade below 10 R/hr shall be by means of calibrated radiation source. The original laboratory calibration is not an acceptable position due to the possible differences after in situ installation .

For high-range calibration, no adequate sources exist, so a n alternate was provided.

SPECIAL Ca l ibrate and type-test representative specimens of detectors ENVIRONMENTAL at sufficient points to demonstrate linearity through a l l 57 QUA IFICAT IONS scales up to 10 6 R/hr. Prior to initial use, certify cali-bration of each detector for at l east one point per decade of range between 1 R/hr and 10 3 R/hr .

NUREG-0737, Item 11.B.3 PASS - Post Accident Sampling Systems Post Accident Sampling Equipment

NUREG-0737, IteID 11.B.3 Post-Accident SaIDpling EquipIDent Position A design and oper~ti:onal review of the reactor coolant and containment atmosphere sampling line system~ shall be performed to determine the capability of personnel to promptly obtain (less than 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months ) a sample under accident conditions without incurring a radiation exposure to any individual in excess of 3 and 18-3/4 rem to the whole body or extremities, respectively. Accident conditions should assume a R,e gulatory Guide 1. 3 or 1.4 release of fission pr9ducts. If the review indicates that personnel could not promptly and safely obtain the samples, additional design features or shielding should be provided to meet the criteria.

A design and operational review of the radiological spectrum analysis facilities shall be performed to determine the capability to promptly quantify {in less than 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months ) certain radionuclides that are indicators of the degree of core damage. Such radionuclides are noble gases (which indicate cladding failure),

iodines and cesiums (which indicate high fuel temperatures), and nonvolatile isotopes (which indicate fuel melting).- The initia.1 reactor coolant spectrum should correspond to a Regulatory Guide 1.3 or 1.4 release. The review should also consider the effects of direct radiation from piping and components in the auxiliary building and possible contamination and direct radiation from airborne effluents. If the review indicates that the .analyses required cannot be performed in a prompt manner with existing eguipment, then design modifica-tions or equipment procurement shall be undertaken to meet the criteria.

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Post-Accident Sampling Systems (PASS)

NUREG-0737 (ADAMS No. ML051400209)

Item 11.B.3 PASS Sampling Capability

Requirements for:

- Reactor coolant sampling

- Containment atmosphere sampling

- Obtain samples within 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months , under accident conditions, without exceeding personnel dose limits (3 rem whole body and 18. 75 re 6o extremities)

PASS Analysis Requirements

Plants were required to develop capability:

- Within 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months to perform radiological spectrum analysis of RCS samples and containment atmosphere for, noble gases, iodines and cesium, and non-volatile isotopes indicating fuel melt

- Consider interference from direct radiation

If existing equipment is inadequate, perform design modifications and procure equipment

Include a capability to perform chemical analyses for boron and chlorides on a highly radioactive sample 61

PASS Systems

PASS systems were installed in NPPs

Plants had difficulty in meeting regulatory criteria

In "'1984, licensees/vendors proposed an alternative to PASS using the concept of a Core Damage Assessment Model (CDAM)

CDAMs were submitted to NRC and approved as a replacement for some of the PASS requirements 62

Core Damage Assessment Models (CDAMs)

CDAMs are primarily based on:

- Core Exit Thermocouple (CET) temperatures

- RCS pressure and water level

- Containment hydrogen concentrations

- Containment High Radiation Monitor (CHRMs) readings 63 *~' U.S.NRC f>rolt"dt11_'l, Proplr .uul '"t' rm,ro,1mr111

NUREG-0737 Radiation Monitoring During Accidents

Item II.F.1 Additional Accident-Monitoring Instrumentation - 3 main criteria:

- II.F.1-1 Noble Gas Effluent Monitoring

- II.F.1-2 Iodine and Particulate Monitoring

- II.F.1-3 Containment High Range Monitoring 64

Radiation Monitoring Design Criteria

NUREG-0737, pg II.F.1-11, Item 5, and RG 1.97, footnote 7 are instrument "Design Criteria" (not "instrument calibration" criteria)

Detectors should respond to gamma radiation in the range from 60 keV - 100 keV within a factor of 2

Detectors should have an energy response accuracy of+/- 20% from 100 keV - 3 MeV 7

' Detedors should tts~ond to g1mma radiation pho1ons v.ithin any energy range' rrom 60 ktVto 3MtVv.ith an cnerJY rtSponse 1ccuraey or 120 percent t any spedfic phoron *eJtugy fto O MeV to J Me V. Ove~II sy1tcm accuracy sl1ould bt ~thin aractor of 2over tbe en Ure nn . , .S.NRC l,rnu, ting l'roplr ,uul tl,t* I- ,,,,,*,111mrr1t

Typical CHRMs Ion Chamber Design Criteria: Dose Rate vs Gamma Energy RG 1.97, footnote 7: +/- 20% from 100 keV to 3 MeV 0.1 MeV 3 MeV l l

+JO

+ 20 % 2 0 IC, l J7 cr6n 2. 5 11,,V I t- I 0

.J 0% 0

-1 0 I"'

~

- IJ I

..FR0*1 2AtP.L.

~ 6.y'U

-l

-JO 0

-S 0 0

I I

I' 0

0

() ,) DETECTOR II ' ' -

TYPIC,\L

) n:Fl!C:Y ~r*M'ISF 10 lOL ,J )xlO,J 66 100 keV

Dose Rate Linearity vs. Energy RG 1.97 design criteria a factor of+/- 2 from 60 keV to 100 keV 60 keV 100 keV 3 MeV Relative Dose Rate Factor u, I Zt-...,._-+-...,........~~a+-r-+-....,.._ ~

of 2 Ill from 60 keV 1

*+/-==t=!::t=t+/-=+/-!b!l:!!~s~~-~- *l--'~k~~b.J..J..J.J-~~ J.J&~

9 to 100 keV

, I 4t----+----+--1t-+--+--+-11+-t~Hf---+---+--+--+-~-+-+--+--t-+-tt-----+-+---++-1!-+-

2t----+-..........+--~-+-........N--+-+--it-a--........,_--+-_......,-+-+-+--+--+-~~to-----+-+--.......ii--+-

I 67 z 2 l '

Module 3 CHRMs Equipment

Typical CHRM Detector

~ 3 inch diameter 69

Wide Range Ion Chamber Detector Pre-amp

Typical CHRMs

Ion Chamber detectors are similar to capacitors, with two electrodes separated by a volume of air/gas

Dose rate measurement

- in the range of 1 R/h to 10,000,000 R/h,

- energy dependence within + 20% from 100 keV to 3 MeV, and

- energy dependence within a factor of 2 from 60 keV to 100 keV

The preamp is housed in a gasket sealed enclosure

Interconnection between the detector and preamplifier is accomplished via two five-foot cables, encased in a flexible conduit

\

71

~ U.S.NRC

/'rotat"1g l'ropll' ,u11/ rhr I nr 1m,1111t"11t

Terminology

Prototype or Design detector

- The original detector that is fully-tested

- Establishes a generic calibration constant in a uniform, broad beam radiation field

- (:";:: ), approx. (lE-11 amps// R/hr)

Production detectors

- Replica detectors of the Design detector

- Vendors made several ("'200 - "'300) production detectors for sale to power plants

Field Calibrators - calibration jigs 72

Production (Replica) Detector

A for-sale" (replica) of the design detector 11

Some manufacturers install an internal radioactive source to produce a 11 Keep-Alive" current equivalent to rv 1 R/hr (Am-241 or U-234)

Is tested by manufacturer in a uniform radiation field to 3 dose rate decades (rvl R/hr to 1,000 R/hr)

Is calibrated to determine its detector-specific calibration constant (a7vs) \

73 R hr *;_ U.S.NRC P,*otrd1'1_'l, /

1roplr '""' rl,,* r,,, ,,r,111mo1t

Typical CORM

Ion Chamber - ceramic detector, 3-inch diameter, 8-inch length

Central electrode is+ 800 V anode collecting negative ions

Chamber wall is the cathode collecting positive charges

Typical Ion Chamber

. Radiation Enters Gas-Filled Tube OUT ~ R CHAl\i SER - CATHODE

e. ~ 1 e r 0 T.r+'*rr

.../

0 Insu lator

~ + COLLECTOR WIRE OR PL~TE' - ANODE"' + + + + + - - - . J . . -....--1* . to Com

2. Ion Pairs ano Fret: Elecr.rnns

,.. . ar.e Released -o v- lncorninif

~ ,. Rad* _t ion.

J 3: lon*Or if t Occur s

. ,.,.e

~ Pos,t ive Ion 4 . Resulting Ion Corrent can be

'-a.© MeasurPd, Yielding *a Quantity that' s * .roportional to t h P. Rate

+ of Arriving Radiation .

Typical Mounting Brackets NOMINAL' RANGE . APPLICATION *

. mR / Hr -:103 R/ H r A.REA 1 mR /H r - 10" R/ H r AREA 10 mR/ H r - 10!; A/ Hr AREA

1

10 7 R/ Hr -AREA

.1 - 103 µCiicc STEAMLINE ANO (0.5 MEV GAMMA) PRIMARY COO u ..::,.1 ~ nC l 1roturmg l'roplr ,ind ti,, F1n*1nmmr111

Typical CHRMs specs

Ion chamber is loaded with an internal Am-241 keep-alive source, then filled with nitrogen at atmospheric pressure, and hermetically sealed

Keep-alive source is 0.1 Ci Am-241 (433 yrs T112 )

or U-234 (245,000 yr T112 )

Only variables affecting ion chambers are collection voltage, fill pressure, and the condition of its connectors' insulation.

Example: Ion chambers exposed to 3 decades between 1 R/hr and 1,000 R/hr.

The average response of the ion chambers, is referred to as the calibration constant, was 1.02E-11 + 5.5 E-12 C1s) rhr

rv 46% variation in calibration canst

Typical Ion Chamber

Contains an internal Am-241 "Keep-Alive" alpha source

Continuous dose rate rv 1 - 9 R/hr, depending on how much Am-241 is installed i

~ U.S.NRC

/'rotutrng l'roplr ,1,u/ r/,,* / 1111r,mm,*,zt

Typical Ion Chambers

Failure modes

- Gradual loss of internal gas pressure (from 1 atm)

- Dirty connectors (dust & humidity)

- Mineral cable insulation - Loss of resistance

- Continuity can only be checked when there is access to both ends of the cable

Spare parts

- No spare parts are needed

- Replace entire assembly as needed 79

Typical Ion Chamber Maintenance

Preventative Maintenance

- Connectors are sensitive to dust and moisture

- Use "caps" to protect connectors

- Clean cables with freon or alcohol and dry with heat gun

- Verify "'lE+ll ohm insulation resistance from conductor to sheath

- V = l*R (1 volt is one amp current through 1 ohm resistance) 80

Other CHRMs Designs

Some Ion Chamber's do not have an internal Keep-Alive source

Instead, they use an electronic signal to continuously display a minimum of rv 1 R/hr

Field Calibrator

The manufacturer builds a device to be used for in-plant calibration called a "Field Calibrator"

Field Calibrator provides a narrow-beam exposure, but in precise exposure geometry within +/- 2% - 5%

Manufacturer determines the "expected dose-rate value" in the Field Calibrator for a specific Cs-137 source and a specific CHRMs

Manufacturer provides the Field Calibrator and a Cs-137 source to the power plants for use in in-plant calibration checks 82

Field Calibrator -with source Photo shows hanger mounting slots to mount device onto detector tabs 83

Field Typical CHRM Field Calibrator Calibrator Ion ch mounted on side of Green is the low dose side

- 3 R/hr Red is high dose side

- 10 R/hr 84

Field Calibrator Description The f -e d cal rator co sfsts of a right circular cylinder fflade of s *t eel enicased lead. It has a circular opening at one, *e,nd ,. eoncentr c wit'h its ax1 s

which exte--ds approx tmiate y two- thi rd.s 1 ts 1e gth. and wh -* ch accomnoda tes . t.he d.etector or 1

(

detec or and - -xture). At ihe end of the c rcular o e -- i g. and at ight a - g - es to. it., ts a rectangt:Jlar cha nel whic.h acconmodates he drawer.

The drawer has three tjecesses 1 n it to accorllllROdate fere

t size sou1rces., a to position the

-lfflled_. tel y below the detector, an cente'r them on 1

the detector axis.

85

Different Style Field Calibrator CHRM is unmounted from installed location, and inserted into the Field Calibrator Field Calibrator

Field Calibrator Description Field ca ibra or an 1 s dra1\*,er affords a s able, reprod c "ble reference geome!!~{

behveen the seconda:n* ., transfer sout"Ce and the detector

- '.1 e field caFb.rator consists o a r *ght cir ar .,Ylinder made of steel encased lead.

I has a circular o ening at one end= c oncentri.c ,..,. *th *ts axis= \** ich extends aE ox*matel"

ti.Yo thirds. its length= and ,.~:hich ac ccmmo da es. the detector (or cletector and! 1X.ture . At the end ofth.e circular opening= and a r*ght angl,e s o ii:

s a rectangular hannel i.vhich accommodates the dra,ver.

1 e drat *er has three recesses in i o ace om.mo date different size source.s, and to position them immediatel

belo,;,- the detector= and center them on the detector axis. The smal rec es.:: is g ener.all:

used or the c ali ra *c,n source. The ar e recess

s generally used for l"neari _- source :L .A.nd the larger~ cylindrical open *ng is sed or counting particula e er iodine cartr.-dges in a repr duci 87

Field Calibrator

.3 rans.fer Sources

... *1

_.:,. e .:lecond.ary trans er calibration s.ources s.upplied as a standard part of a s.y"te are one inch *n diame er, and mould be placed in the one inch d *ameter recess. in the dra'i:rer. .a\ho~ h -o inc diameters urcesmai.* be :;ypplied for ineari

sour .. es.

; ~ urce s laced in the two in h diameter recess.

43. Sour~ seri ize<L and en n appli ble !rta ~beets along , -~

e ccnm data.

43. Sources shall be placed

pr drawer recess \.\

onl.r the omce

etted and the assa:

infonnation facing m -a .r from the detector. (Do not pl ce the planchet in e drawer with the so rce. IS only med for sonn:e storage.)

43. Two s~ts of

condarv ................a cahbr -on. ASI ard cali *

ource s:et rill e ..!\SI -ati n e !h"il1lna rs st md calibra .cm v. . be transferr d cu:f ers fur field calib ration . . econdary w-ces have S thr ugh e hr....t-. ....sn " ~hioh is perform c:od 88

Trans£er source in Field Calibrator 1.5 The secondary transfer calibration sources supplied as a stan,dard part *of a system are one inch in diameter, and should be placed in the one inch diameter recess in the drawer. Also 1 a two inch diameter area source ay be suppl ied for l inearity sou rces. This s~urce is placed in the two i 1nch diameter recess .

1. 5.1 Sources used will be ind*v;dually serial*zed 1 and that number written on the manufacturer's source activity certification. as ,wel:1 as appl icable data sheets and/or, l og: books ,, al ong wi th t he count data.

89

NBS Traceable Sources Two sets of disc sources are used in the seco dary transfer ca11bra fan. standard cal *brat*on source set w* 1 be P-ennanentl kept b the Rad*at*o ab. e customer's standard calibrat*on source set wi be transferred to customer for f;e d calib ation. All the secondary so rces I

have N .S. traceabilit thro gh the pr*mary isotop c cal fbration which ;s P-erformed with N.*B.S. traceable isotop *c

~~

.so rces .

90

Typical Transfer Source Certificate CERTIFICATE OF CALI BRATION SEALED SOURCE GAMMA RADIATION DOSE RATE T'H: Gamma Ray A" r l\bsorbtion Dose Rate resulting from radiation emission oft e subj ect sou rce was determined to be 30 . 84 m~illiroentgens er hour at an exposure point 1.0 meter {39.4u) djstant ,

approxima e ly per end*cular to the caps~le longitudinal axis center li ne.

The measu rement was perfor ed using a Precision Io ization Chamber/

r:-1ectromc~er System fer *..-;hich the dose equivalent response of the s ubject source was developed by comparison with __N. B. S. Cobalt-60 Dose Rate Source Standard #47342 x N.B.S . Cesium-137 Dose Rate Sourre Standa r d

47455. Th e overall u~certainty of the measurement value is estin- 1ted to be - 4%.

= 30 mR/hr at 1 meter, or using inverse square law

"'77 R/hr at a point at "'2 cm ("' 1 inch)

"'12 R/hr at a point at "'S cm ("' 2 inches) !

91

~ U.S.NRC l'roft'drng, lh,p/r .uul rlw Fm *,ninmrnt

Calibration Source Lead Shield The calibrated source and shield sets a e designed and constructed for easy use and mi nimum radiation exposure. The sh*eld and

~ourcc weight of 27 kg (~60 lbs) can easi1y be transported using the handle . The padloc prcvcn s any unauthorized us, of the ca librJted source. Pictured below is he shield and source in the storage mode with approximate dose rates given i ri the table.

Drawing for a Source Shield j

STORAGE-RAOIAT.ION DOSE RATES

(mR/hr/mCi)

Source Co-60 Cs-137 Cs-137

1. ----- -- - - Nuclide 1 mR/hr At Shiel d 2 .8 0.01 Surface (100 mCi) 2" (5.1cm) 1.0 <0. 01 From Surface 6" (15cm) 0 . 31 <0.0 From Surface

( 12 " ( 30. 5cm ) O . 11 <0. 01

- j From Surf ace Dose r ates measured using TLD

. It Li F *c h i ps I. 2 5 crn2 (1 / 2 " di a. )

8 f l

!'2'\.? ./

M .) ~

. 1 93

Typical Source Shield To remove source from storage shield, first. place shield skirt on horizo~

surface. Then unlock padlook and remove it from*padlock hasp . After lifting the shield handle, pull out th~ tungsten plug. Insert source handlling tool, thread side first, into the tube and thread it into the source capsule . (NOTE: The anti-rotate fixture will prevent rotating the ~ource capsule.} Yo11 may now remove the source.

Reverse the above procedure to return the source into the storage shield.

---i'r/

~-- * - 18 /JJ.r.7c.w7 ~

I '.J " -1 ~ ca 1cu 1a t e d dose r a te ;

~~C~~ P~:=:_ _ 60Co . "-0. 2 mR/hr/mCi CA SlJl ~ l J D1.ING ROD 137Cs "'1.5 iTIR/hr/mCi 94

Box Calibrator

Box Calibrator Module 4 CHRMs Calibration Process

Calibration

What is a "Calibration?"

What is a "Calibration Check?"

The terms are used interchangeably

Basically:

- A calibration check evaluates if the instrument is working properly, and if not, then

- A calibration is the adjustment of the instrument output 98

Manufacturer's Primary Calibration

What is a "primary calibration?"

Plain language: The manufacturer's measurement of the detector's response to a uniform exposure geometry (similar to the radiation field in containment during an accident)

~ JE-11 (amps)

R/hr

Ion chambers are very stable - normally no need to adjust the "calibration constant" 99

In-Plant Calibration Check

Purpose - to demonstrate that CHRMs are working properly- i.e., the CHRM is functioning the same as it was when calibrated at the manufacturer's facility

The calibration does NOT require the exposure geometry to be a uniform exposure geometry- instead, use non-uniform exposure geometry in a fixed geometry

Manufacturers establish a repeatable geometry for the non-uniform exposure using a Field Calibrator

The non-uniform exposure geometry must be the same as the geometry when the detector was known to be working properly \

100 *~ U.S.NRC

/

1 rothtrng l'ropl,* ,utrl tli,* F m *n*,mm,*nt

In-plant Calibration Check

What is an "in-plant calibration check?"

Plain language: Two parts: Electronic and Rad Calibration

- Electronics Calibration Check

- Radiation Exposure Calibration Check

A check to determine if the CHRMs are still working properly

Make a comparison of the CHRMs instrument response (R/hr} to the manufacturer's expected value (R/hr}

The expected value was determined by the manufacturer in a non-uniform, fixed geometry Field Calibrator

The expected value is decay corrected 101

In-Plant Calibration Components

1) Radiological calibration

- Compare detector dose rate (R/hr) response to an expected dose rate response (R/hr) in the Field Calibrator

- Requires a fixed geometry and knowledge of the dose rate when the manufacturer established the Transfer dose rate in its Field Calibrator (in a non-uniform geometry standard with a Cs-137 source)

2) Electronic calibration

- Injection of a simulated signal as close to the detector/sensor as possible i

102

- Test upper ranges 10 R/hr to lOM R *~ U.S.NRC Protf(tt'1g Proplr ~uu/ 1/,,* F 111 *1ro11mrnt

Exposure Geometry

During an accident, the exposure geometry is a uniform, broad beam geometry

- Ideally, CHRMs mounted in a 4 rr (360 ° geometry)

- CHRMs are mounted onto a concrete wall is a 2n geometry

Uniform exposure geometry is used when determining the calibration constant, t7vs),

R hr to simulate exposure conditions during an accident

During periodic in-plant calibrations, a non-uniform exposure geometry is OK 103

Manufacturer's Primary Calibration

The manufacturer's primary calibration determines the "calibration constant" amps R/hr

- The primary calibration uses a uniform exposure geometry

{similar to a containment radiation field during an accident)

- the manufacturer exposes the detectors to various dose rates and various gamma energies

- They measure the detector amperage for each dose rate

- They average the output and determine the "calibration constant" (amperage per R/hr) (~ lE-11 a7ps)

R hr 104 *~' U.S.NRC

,,,*otutrn_'l. l 'rop/r ,ind tl,t* l .llurm1111ent

Example Energy Response Testing H Rt.: : . ,.,3!A7lO:~ *.:"':: R T p .. I * : .;

E? ~- S~==-*-?.Y A S U, f S URCE E'E Y O' *SE RA E RESP :*s£ (R/HR) ( AJR/HR )

Co- 60 {RAO L) .66 l . 06 x 10-l l Co-6 , R-S) 1

17 1 . 33i* £ 102 1 .. 16 X ,.Q-11 Co-60 (S. LK) 4 X 103. 1. 1 X 1o- l l 3 X 104 1. 03 X 1 o-11 Cs- 137 662 KEV 1 1 . 1J X 1 o-1 l 2 1,

08 X 1 o- l 1 5 1. 07 X 1 o- l 1 2 X 10 1 1. 01 x 1 o- 11 XRAY 70 KEV (E FF ) 3.7 9 . 14 X 1 0 - l 2i 1: 1 7 t(EV ( Ef F ) 1.5 1:

39 X 10- l, l, 1 6 7 I:£ V ( E FF- ) 1.*9 1 *.019 X 10-l 21 0 KEV (EFF ) 1.4 l .O 3 1 (:'- 1 L J:; EAR ACC ELERATOR 4.5 MEV {Al/ 5 X 106 1. 1 3 X 1 o- l

NUREG-0737 criteria (CHRMs)

"Design" detectors - dose rate tested to 10 million R/hr

"Production" (replica - for sale) detectors

- Every production detector is tested in first 3 decades

1- 10 R/hr, 10 - 100 R/hr, 100 -1,000 R/hr

- Electronic calibration above 10 R/hr

- In-plant calibration at one point below 10 R/hr 106

Replacement Calibration Sources

Cs-137 sources in Field Calibrators (calibration jigs) are "'30 - 40 years old

Source strength has decayed "'40% to "'60%

Source certificates give activity and assay date

Dose rates from replacement sources in Field Calibrators can be obtained by ratio of source activities (new source activity vs. original source activity 107

Typical Source Certificate CERTIFICATE OF RADIOACTIVITY CALIBRATION soto e; Cs tJ ? Half-Life: lo,o y Source No.: 8'I '1Z.3 Was assayed as containin : / I 'I ,..,,, 1/2*

As of: 11 - J-.Bf METHOD O CALIBRATION:

( ) The source was assayed on a 3" x 3* Nal {Tl) crystal i conjunction wi th a sing!

channel analyz r,, using the MeV peak a value of gamma rays per decay was used in he calcula1ionsl. againft tandard No. , in the same geomet ical arrangement. _,

,7_1,q.&&*ri tf't" 1'0-. ~'--t

( X ) The sou ce wa a *yed in a . . ii *proportional counter against es-~1J?

standard No. '17'(8'/ .

{ The sourc war. a sayed by alpha s ec;trometry on a surface barrie detecto in conjunctio

with a single-chan nel analyzer, against standard No.

in th sam geometrica arrangement.

The source was prepar fr m a welgh d aliquot of a solution whose activity in

µCi/gm was determined by the method Indicated above.

108

Typical Source Certificate (Cont.)

Page 2 of 2 ERROR CALCULATlON :

a) Systematic errors (SE)

1. A ccuracy of the standard: J . *c, f

2. "

b) Random ,e rrors ( A E.l

1. Precision of s,ource count, P. :

2. Prec1sion of standard ,eou nt e~

3, Error due- to bac ,ground, e3 :

c) T otal

r ,o r T E= SE+ RE+/-~~';!

NOTES

( X') The erro.r given is calcu lated a t e '?, % confi d-.nee I vel.

( 'I This eall br

Ion is directl y / indi ectly basgd on NBS Standard Re'erence Material

No.

CERTIFICATE OF CALIBRATION Standard Reference Source SRS Number: 111308A Source

Description:

12 cm x 12 cm Plate Source Product Code: CO0*LDS-1 00MM customer:

P.O. Number: 02389833, Item 1 This standard radionuclide source was prepared gravimetrically from a master solution calibrated with an ionization chamber. The ionization chamber was calibrated by the National Physical Labor tory {NPL), Teddington, U.K., and is traceable to national tandards. Radionuclide calibration and purity were checked by germanium gamma-ray spectrom try, liquid scintillation counting, and/or alpha sp ctrom try, as applicable. The nuclear decay rate and eference date for this source are given below. Eckert & Ziegler Analytics (EZA) maintains traceability to the Nation Institute of Standards and Technology (NIST) through a Measurements Assurance P ogram as described in USNRC Regulatory Guide 4.16, Revision 2, July 2007, and compliance with ANSI N42.22-1995, Traceability of Radioactive Sources to NIST.

Reference Date: 22-January-2019 12:00PMEST Uncertainty Calibration Half-Life, d Activity1 . UA, 1

/4 u8 , o/ U, %* Method..

1.928E+03 8J96Et03 0.1 1.6 3.3 .. . IC

'll'{J'ncertainty: U- Relative expanded uncertainty, k = 2. See NIST Technical Note 1297, "Guidelines for Evaluating and Expressing the Uncertainty of NIST Measurement Results." HCalibration Methods: 4TT LS* 4n Liquid Scintillation Co\11\tmg, ijpGe - High Purity Cenna

Gmma-R11y Spectrometer, IC - Ionization Chamber.

110

I

'-......, .S.NRC Protrding J*rople and rl,,* r ,,,,,ronmrnt

Foreign Sources

NIST-Traceability may be established by conformance with a foreign National Standardizing Laboratory (NSL)

The NSL must provide NIST with documentation that guidelines from the International Committee for Radionuclide Metrology (ICRM) have been met 111

Four Basic Calibration Steps

Step 1 - Manufacturer calibrates the Prototype (Design) detector (determine its energy response, linearity, and determine its amps)

(

calibration constant Rf hr Step 2 - Manufacturer calibrates the Production Detector (i.e., prove the production detector's performance is equivalent to the Prototype (design detector)

Step 3 - Manufacturer calibrates the Field Calibrator (calibration jig) to its Production Detector- i.e., determine the CHRMs expected response to a specific Cs-137 source in a fixed geometry

Step 4 - Licensees perform In-Plant Calibrations using the Field Calibrator to determine if the CHRM 112 is still working properly U.S.NR(~

/,mt,*( ,,,,g /'ropl,* ,uul ti,,. I m n*011m,*11r

Step I Primary Calibration

Determine detector's energy response characteristics

("'80 keV to 3 MeV).

Verify dose rate linearity check to 10 million R/hr.

Determine calibration constant (efficiency factor) in a uniform external beam t7ps)

R hr

- Ion chambers produce amperage (amps)

- Microprocessor converts amps to R/hr by dividing the amps by the calibration constant t7ps)

R hr

= R/hr 113 *~' U.S.NRC Protatrng / h,plr ,uul rlw F nr rn111mo1t

Exainple: Priinary Calibration of Prototype (Design) Detector Calibration TABLE l Nuclide Energy PROTOTYPE CALIBRATION DATA

Amps Amps/ R/hr

- Meaaured

'true Doae Ila te. Detec tor Senaitlvity, Source !ncrg,- Refer nee Data lt/hr Response A/l/hr

. I

1. Co-60 O. 5 Ci 1. 17 MeV

AJr ion chamhel' 0.6625 7.0lS x 10-U A 1.06 X 10-ll Radcal Corp. (av of two (av of two l.33 KoV teeta) teeta)

2. Co-60 1.17 Me\t 1 R -C4-l606-203 109. 7 1,262 X 10-g A 1.15 X 10-ll Rut , r-Sto\<.~ e calibceted by NBS 1.33 MeV 4 10-l A 1.14

l. Co-60 l.000 Cl 1.17 H V 1 Landaverk L64 3.9 x 10 4.46 X X 10-ll Toentgen meter 1.33 MeV

4. Ca-137 662 lr.eV 'RS-C4-1606-203 1.0<*> 1. 13 x* 10-ll A 1.13 11 lO-ll GA calibrated by NBS 2.0<*) 2.17 X 10-ll . A 1.08 X 10*11 5.o<*> 5.37 x 10-ll A 1.01 x 10- 11 20.ofa) 2.03 x 10-lO A 1.01 x 10-ll (a)These readio a~ould not b averag d. A collimating geo etry ror at 2 !/hr end above 11 inherent in the 1ource holder and 11 inalgntficant in smaller detectors.

114 *~ U.S.NRC

/ 'n,tt"t llng /'roplr ,1111/ r/,,. ,-,,, ,mnmr'1I

Example Primary Calibration Data CHRMs X-ray Energy Dose Rate Amps Amps/ R/hr

5. -9 9. 14 10.. U l ray 70 keV (eff) Air ion chamber 3.72 1. 01 x 10 C X 117 keV (eff) Air ion cbaiaber 1.5S 1.2Sxl0

-9 C 1.39 X 1()-ll

..9 167 keV (eff) Air ion chaaiber 1.91 1.16 x 10 C 1.19 x 1o*tt 210 kef (eff) Ai i on chai.b r 1.39 ' 1.24 x 10

-9 C 1. 13 1t 10-11

6. X ray 43, S. keV(b) L1nd1verk L64 19.5 1.27 x *10-lO A 6.5 x 10-12 GA 60 keV(b) roentgen

cter 24 .2 2.40 1t 10.. lO A 9.9 " 10*12

1. Linear 5,*17 106

. -s 1.u ][ 10..11 4,5 HoV (av) fhotochromic dye :ic 5. l 7 x 10 A elera or a

lRT Co P*

doatmetry (a) These reading e ehould -not be averaged. A coll i mating geoaetry t1rror at 2 R/hr end above 1a inherent in th aourco h~lder and 11 inelsntficant in a aller detectore.

(b) e S tion 3.1.

115

Energy Response Testing ESUL S USI , G T E ION CHAMBER En,er gy Avera9 Increm ntal Rad iation Sou rce Leve Current Current Fi e ld Sens i iv *ty

( MeV ) ( 10 11 A) (lQ - llA) (mR/hr ) (l o-11 A/R/hr)

-~

57co 0. 122 1.21 14 +/- 0 .0011 0 . 01 24 ! 0. 0017 11.3 1. 09 ! 0 13 133sa 0. 356 1. 457 ! 0. 0014 0.258 !: 0.002 245 .0 1. 05 .!: 0.008 137cs 0.6&2 1.245 ! 0.002 0.046 .t 0.0024 45 .2 1. 02 .!: 0.053 60co 1.17 1.279 +/- 0. 00l4 0.080 +/- 0.002 77. 3 1 .03 !: 0.02S 1.33 No Source 1. 199 0.0014 i

~ U.S.NRC f*,*oftYtmg /'rop/r ,uu/ tl,t* Fnr ,rn,,,,u,11

Energy Response Testing

!-B 1 _l,e~, IR ~Jl~-~

r he ove*r a 1 J response of the *on ,chamber 1s. 1 . 05 x 10 ~ 111 A/R/hr etwee 10-0 and 101 R/hr ~

B S-2 ;,;;;;,,,,;,;,;,......,.-

Ener ..

Th e ener ies.

_ ____:===--:;=:::::::;;;:=~-=--=-------=-----=-~=----"-=~--=----~ nd J.Q MeV is ! OS of the nom1 na 1 1 . OS x 1 Q B 5- 3 Test Accurac The cal bration accurac~ is 71 .

s 291 .

Typical Radiation Detectors Containment High Range Monitor

In 1981 and 1983, a manufacturer performed the Design detector's primary calibration and provided:

- A 408 page Instrumentation Manual

- Only data available is from the Calibration Summary Report amps

the calibration constant was 1.02E-11 ( / )

R hr

- Difficult to find the data on the energy response testing or dose-rate linearity up to 10 million R/hr 118 *~' U.S.NRC

/'rotating /h,p/r ,11,r/ rl,,, F 111 ,,nu11,101t

Typical Design Detector Primary Calibration D M NT

. TA OARD PRAC IC P OC UR .

IO n. ctor SUMMA

odP. l I <j}'~ I(' '3:/;,. -*;:; 2

/tJ .:z J S-J l WWW -

. OESJGN CAL1 BRA N A. Pr i ry I

~ ----__;;:._____

ncy ( Re,f . r e p-0rt n am s/.~ ...11.1.1...--

1 B. I* t m 'lo e

A so e f c, n

5/ N #k N/A i 119

Typical Ion Chamber Specs

~ IE-11 Amps per R/hr KDI-.1 KDI-1 I KOI-10 KDl-100'0 KDI-F Insulators; *Ceramic Ceramic : Ceramic Ceramic* Ceramic

-Outershel 1:. s.ame Same 1 Same Same Stainless Steel Electf'lodes: Aluminum ,Al um num , Aluminum

Aluminum A gon/N,itron Argon/Ni t ron itron Xenon Fi 1-1 Pressure: 20 Atm. 20 Atm 1 40 Atm 1 Atm AJ'.!P rox 25* Atm Di a eter: 7. 0

in.- 7. 0 in ' 3. 5 i 1n. 3. O in . 3.5 in.

Act i ve Vo 1ume: 5200 cc '5200 c,c - *400 cc 160 cc

Approx 8

in.

I Overan l ength: 18 in.. 18 in. . 8.0 i*n. 8~0 in.

Sens1tivity: _ *6-.5E-9ALR/hr . 6_.5E-9A/R/hr : l.2E-9.A/-R/hr . *lE-llA/R/hr

*o~.minal .. Range: . *. lmR/~r-l0 3R/Hr lmR/Hr-l04R/H~ 10inR/Hr-J.0 5RJHr -to1_R/Hr .t~lO~ micro-Ci/

cc (O. 5 EVgamaJ nte*r*na 1 Test .1 micro-Ci .1 micro-Ci .1 micro-Ci - O. l micro-Ci/

Source; - Am-241 Am-241 Am-241 America ni um 241

to pr,oduce 1. to 5xlo-ll Am s * -

120

Typical Ion Chamber Energy Response Tests B- 1-I

~

1 USNRC . .

!'rotl'ctlng /'ropl,* .1111/ tht* J-:m *rmnmoll

Step 2 Production (replica) Detector's Calibration

Objective: Verify the Production (replica) detector's response is equivalent to the Design Detector

Perform a 3-decade dose rate check (NUREG-0737)

e.g., 3 R/hr, 30 R/hr, 300 R/hr

Verify the calibration constant (a7vs) is the same as the R hr Design Detector

Answer is ~ 1.0E-11 a7ps R hr 122

CHRMs Calibration 8-1 1 1R

u.,rementi The* 1ghwr nge ~n~containment area (HRICA) detectors (drawing 609 209 &) ca1i br.a ted at the de tee

0 7 act v1 ty in . he range of 10 to 10 R/hr O"r r an energy range of 80 (eV to I

3 MeV. Th,e det ctors r.e ua 1if* ed to unct io n during and after a lass of I 1 ool n cci,dent (LOCA) aximum a,ccid nt temperature *,s 400'"F, and x mum cc dent pressure i 50 ps1g .

123

Typical Production Detectors Linearity Tests L 1 n 1¥ du l

c. a be :

f 11 s;_

0 ta

Typical Production Detector Calibration TE ST OATA

~ i gh Vol t. l1~w Setting +. Boo v Acceptance* Criteria Ot hrr inst r ument Settings ( if a*ppl icab l e ) 11

8- to 1#'2 (I0 - ) A/R/h r Check Source/L iv ~ Zero Readi ng ,. lr'o E-11 Keep-alive (K.A.} amps Mcasurrd Fir l cf In s t r ument Readi nq Dose Rat! GROSS NE A/ R/HR

. ,rta (10 )mR /hr , 9o G"- 11 amps

'S"'- 0 4

(10 ) mR/ hr

.a¥ G-,,

698 mR/hr ~ 5

. s1° ( 10 )rnR/hr

r6 G - 11 5.60 R/hr 6

.71/8" ( 10 )mR /hr _ li- .y E-11 57.8 R/J,r 748 R/hr Example: Gross amps (2.03E-11) minus K.A. amps {1.40E-11) = 0.63E-11 amps Calibration constant =0.63E-11 amps/ 0.698 R/h r =0.90 E-11 a7ps R hr 125

Typical Production Detector Production Detector's Calibration

~I. ACTORY CALIBRA IO (da a shee )

D. Tr f r fi ( Kama ,,v/,,4 )

i Fae ory ur r e _ "io n ( t1 J, cJ *d 11 a, Sl c r 1 i t g ) N/A F. Fa t o ry Ca ib atio 1 Co st ,,t

/, C /i" I I G. Factory E i ci 1 y (C u om *r S

- - - - date 1 /lf/1, )

7, .rI # - II 1t1 et ct n p~S= ~::..:..:....--1..S........::.....:....=-==--

~' U.S.NRC f*,-ott*ctrng l'toplr ,,,,ti r/,,.F 111 *1nmmr111

Step 3 Trans£er Calibration of the Field Calibrator

The purpose of a transfer calibration of the Field Calibrator is to develop a method for the nuclear power plants to verify CHRMs are operating properly

One method is to design a Field Calibrator and then measure the CHRMs response to a Cs-137 source in a fixed non-uniform geometry

ifhe exposure geometry is NOT a uniform radiation field across the detector because the source is too close!

The vendor measures the CHRMs response (dose rate) to a specific Cs-137 source loaded into the Field Calibrator; e.g., a previous example was ,v 7 R/hr at ,v2 inche 127

Summary Transfer Calibration of the Field Calibrator

Manufacturer builds a field calibrator

Loads a Cs-137 source into the field calibrator

Exposes the CHRM to the source in the field calibrator

CHRM detector produces amperage

CHRM microprocessor divides the amperage (amps) by the calibration factor t7ps)

R hr and displays (R/hr)

Document the result in a Calibration Summary Report and send it to the plant for their use in periodic calibration check \

128 *~ U.S.NRC f',-oftY fl11_f!. /'roplr '""' 1/i,* r,,,.,ro,11,,r,,,

Field Calibrators Field Calibrator

Cap Field Calibrator for an Area Rad Monitor ( ARM)

Source holding cap fits over detector to establish a fixed geometry Issue of Concern: The Cs-137 source had decayed. Instead of buying a new source, the plant used a Field Calibrator designed for a different detector.

The ARM did not have a mounting tab, so the plant used a stanchion to mount to the detector without having an equivalency evaluation.

130 *~' U.S.NRC l,rott'ctmg /'roplr ,uul r/rf F ,,r,1rrmmr11t

Containinent AREA monitor

( no mounting tab for Field Calibrator)

No mounting NT tab for calibration source.

131

Home-made Field Calibrator stanchion for mounting calibration source Area Mounting ~ nllll!!c Radiation Hook Monitor Stanchion Issue of Concern: Is there an evaluation showing this geometry is reproducible and meets accuracy 13 2 criteria (+40% or +50% ?)

Home-made Bar Field Calibrator Back

Three source slots source slot

The back slot is for the source when used for Middle low dose rate calibrations source slot Front

The front slot is used source for high dose rate slot calibrations .-.....- Fits over detector

Is there an evaluation of accuracy and reproducibility?

133

Manufacturer's Trans£er Calibration Report

- . CALIBRATION REPORT HIGH RAHGE RADIATIOU MONITOR CALIBP.ATOR The High Range Radiation Monitor Calibrator, Serial No. 006 was calibrated on 11-1-81 , at - * * * * * * * -* This calibrator was found to produce the following effective dose rates:

3.10 R/HR 00 *11111111 Low Side High Side 10.8 R/HR at l foot In Housing *15 mr/br 134

Typical Field Calibrator (pg I)

CALIBRATIOU REPORT HIGH RAt~ E RA A 101~ MONITOR ~AL lBRATOR RT at-********~ is The High Range Rad iati on f'.onit~r a ibrator, Serial No.~

was calibrated n 11- - s *.

calibrator was fou n to produce he foll owi ng ef ec ve dose rates*

on *ow S*ide 3.23 R/KR High Side 1.2 R/Rr{

135 at 1 foot In Hous i g 15 m /hr

Transfer Field Calibrator (pg 2)

The fol lord ng pl"locedure wa s used to obtain the above va 1 ues:

A detection channel consisting of a detec~or calibrated with traceability to :,.e.s. ~ a and a hig h vo l tage po\>1er supply adjust@d to 875 vo s C was connected 1..0 determ i.ne t he s i gnal current resul ting fr om t = do;:)e rat e applied .. The signal curren

obt ai ned was div*ded by t he ca, ibrated detector sensitiv' ty t o obtai n the effectiv e dose r ate . h' s ~asure-ment was pe rf or ,ed f or eac side of the calibrator to provi de 1eve s for a two point coli bra i o

The l foot read ing was made using n Ion Cham 2r survey meter.

Oata Sub i t d S, ~ , ...,. .

rr-~ ,r Dat e Oa ta R vi e;,,-=d By_.,...-;1....;.~,.__-_ -.,,.__ _ __ _ _ _ _ _ __

Signat re Date 136

Trans£er Field Calibrator (pg I)

QA certificate SUft'PLIER -<'J.UALITT. ASSUAAHC£ CERTIFICATION "Date __ i-_1_e-_s_2__________;

of Svpp) ler ---,iiiiiiiiililia*liiiiiiii*r- - - - ~ -

.ss of Supp1 ie1" Pt a y Court NTU Power Otde.r Ho.

hke t tcm or Re.-q. Ho. 1 N/A Her- 10 Nos

0615 Rev . A

.rfption of Component(s} or Material (s)!!!!!!~ C:,:A~l~i;!;b!E!a!2_orr....{;(lLJeua~.j)_ _!Se~ri~a~lLJN~o~._QOQ062.,:_._ _ _ _ __

Atbche'CI 'Oocumentation c;overs all tam;,c:ments/Haterla1s on Nill Pow r Ord r.

Attached Pocu.irentation covers partial shtpment of CofflJ)on nts/~teri h , on Hill Power Ord r.

following 1iHed tesu, inspections an_d reports have been i;oir.p1e:ted requtred by th&

,as

lfh:.ation:

~-~

Certificac:io Data Shee*c: - .

~

Lek 'Test Cer ifi cat Cer~iffo.a.t.e of Radioa..ct:ivi ty Ca.libr.a t:i 137

Transfer Field Calibrator (pg 2)

.. CERTI Fl CATE OF RADIOACTIVITY CALJBRATJON sotope: a:-~.J 7 Half-Life: 3c:,. o y Z.

Source o.; 'if I (. / 7 Was assayed as oontainin

~~,~~~

METHOD OF CALIBRATION:

C ) The source was assayed on a 3" x 3" Nat (TI) crystal in coniunction wit a singl~

charmel analyze r. using he MeV peak ( a value of gamma rays per decay was used in the calculationsl, against standard o . , in the same geometrical arrangement. . ,!

A .,_

~~u-r.z~ ,,_ ~ -

( X) The so rce 1,,*.*c s assayed in a wia-;:!Qwle,, in-err.I proportional counter against a-,a?

standard No. '1"7't~'I .

( J The source was assayed by alpha spectrom!!l:ry on a surface barr*er detector in conjunction w i ha single-channel analyzer. against standard No.

in the same eometrical arrangemr.?nt..

( -) Thtt source was prepared from a w ighed aliquot of a solution whose activit",' in

,1tCi/gm was determmed by the method indicated above.

ERROR CALCULATION :

al Systematic errori i:S E}

l. Ae...--uracy of the st.andard: :t # 9,1.*

L

b) R ndom erro~ (REI

1. Precision o sou ce count. e,:

2. Precis io of st.anoard count, e,:

3. Error due to background, eJ:

RE .. *Vle 2I + e 22 -+ e :,2 .:! 4./dff 138 c) Total Error

Transfer Calibration 1.2 The- secondary t ra*nsfer ca 1111br,a tion has the f o11owin,g charact er1stics

a. Use of a Standard f;e l d ca l brator to perfonn ca 1ibrat ion.

b. Use of a Standard Drawer to fix exact repeatable position of seal ed secondary transfer source, in the standard fiel d calibrator. (t3S)

.1 .4 The field calibrator and its drawer affords a stable, reproducible reference geometry between the secondary mtransfer source and the detector ., *,(Ref er ence sec*ti on 1. 2*.b) 139

'--- U.S.NR(:

/ ,mtnt , I ,*

. : t11g rop /*t ,lttt/r/,r / 1111rm111101t

Trans£er Calibration

1. 6 The genera 1 procedure for* a supplied detector is to:

1.6.1 Count standard sources in the field c*,a lfbrat,or (to olbtain the ind1v*idual dete*cto r 1

abso 1ute ,e ff 1ci e~cy) .

1.6.2 Cou:n t the ,customer 's refe~enc.e sourc,es in the field ca 1i bra.tor.

Provide the customer the expected response: i.e.,

the customer 1 s source (decay corrected) results in a specific detector readout; e.g., how many R/hr 140 *~' U.S.NRC f*rott'dtng l'roplr ,,,ul th,* r ,,, ,,,*m1nu,zt

/MC"'1/lll ~ ez z " .. .o/

DATA SHEET, DETECTOR C -1 I BRAT ION . ,/,;0 ~~/.13~-001 CN~

Customer Tag No .. /,Q/9...vJtaa;tt.B P.n*t No.

Serial No.

A. Date of Field Calibrator Calibration 9'-f0-8.?

B. Date of Field Calibration /t? ~/o/ -8,J

C. Time i nterva 1 (yrs) 8-A = ~(7 z: ::

t . d -

6 9 3~C/--:-::3:-x-0-.~17=-----

D. Ra d ,oac ,ve ecay = e E. .Field Calibrator R/hr Z 22 F. Present Field Calibrator R/hr =OE= _ _2~2~2~---

G. Present Detector current (microprocessor in Calibrate mode)

. ~H (incl ud*i ng significant background) /j OCX/d H.

-11 Present detector gross Field Calibrato current -~9-,_~~-2--X.~1/~---

I. Present C21 .l ibration Con .. tant to be entered into microprocessor =

F/ ( H-G) = ~ 1:, J'ld. '"_ R/ hr/ A

Field Calibrator's Calibration Data B. Date o*f f i d C lib at. on /~ * / Y ~~:r C T me in erv y rs) B-A = --,,.1!.,J

~ ~- - --

-. 693 C *3.

Radioact i v de a, = e Fie*ld Cal "b t or R/ r z* 22.

F. Prese rt Fie l d / l r =- DE == 2 22 G. Pr ese nt Dete tor cu r ent m c oprocessor *n Cal i bra e mode)

-~~--~---

( i cl ud i ~g s i gni fica t bac ro nd) 6 tz:'&4

,/

II c or gross ie ld al "brator current II I.

' li ration Cos n to be e n ere fn o m*c oprocesso =

EST EQ IP E T IT Fi~Jj Ce,~ .6.

142

Field Calibrator C£ TIFlC IE O CALIB TI 1 1.s hereby certifie th t quip nt isted below bas bee calibrated, pe~ ot roal proc du"t:e , and i trace , ble to th l~ ion 1 Bureau of docum o ati o is on _il a s for our evie *

~.iiiiiiiiJ Model . o . Calibr or S ria umb r 18 iel Va l u *1 o. 0 Sincerely Manage., Q l

y A suraoe 143

Field Calibrator Calibration Summary Report

- Determined by measurement of the transfer value for the detector in its Field Calibrator jig was 7.72 R/hr

- Cs-137 source was "' 100 mCi Cs-137

Source Certificates CERTIFICATION DATA SH£ET CUSTOMER: P.O.# 772 702..

CATALOG QUANTITY: JI CAPSULE TYPE: ,:,,,e c.,,,,., *~"" r11w NATURE OF ACTIVE DEPOSIT : C '-(./ ,.,, 4,,JJ,,* .,.v ,.,,_,,,,,e -t'/"f"'k"f'...,,-f-ACT1VE DIAMETER :

BACIONG :

COVER: -

145

Sources Purchased by Manufacturer froin Source Supplier ISOTOPE SOURCE I AC IVl Y C.A . OA . NCER TAI TY cs,137 g,1 b J 3 o I I'-/~ l,'

i "' I, ti , ... 81

'f . 10'1 S ooY 11'1 t, oo ':> Jo~ (

7 00 101 I REMARK :

8 ,oc7 I desc ibed ere are in co, t1 ia ce with all a icable

' (

'i "" 2 flj s pec* f icatio _s .

1.C ,oc, I Ol 2,. .

\

I "r

f?,;

J (M, I~ HU

Source Certificate Page 1 of 2 CERTIFICATE OF RADIOACTIVITY CALIBRATION *** ** * - *, ..

soto e; Cs tJ ? 2..

Source No.: fl"Z.3 Was assayed as contaiflin o. / / '{ ,.,, c;

Asof: ,,-1-..s, METHOD O CALIBRATION:

( ) The source was assayed on a 3" x 3 Nal {Tl) crystal in conjunction with a single-

channe1 analyzer using th MeV peak a value of gamma rays per decay was used *in the calculationsL against . ndard No. , in the same geomet ical arrangement.

( ,."* )

- °""' ifr.L.-~.

The source wa a yed .in a# 'fl S.&*r-; l.~tl. . CJ ..1.J'?

propo t1onal counter agamst standard No. 'f?'f 8'1 .

The sourc

w s a sa ed 'by alpha s ectrometry on a surface barrie detecto in conju.nctio

with a single-chan nel analyzer, against standard No.

In th same geometrica arrangement.

f ) The source was prepare from ai welghed aliquo of a *solution whose activity in

µCi/gm was determ ined by the method indicated a ove.

147

Source Certificate Page 2 of 2 ERROR CALCULATIO :

a) Systematic errors (SE)

1. Accu racy of the st ndard: .!". t::JJ

2.

b) Random errors ( A E)

1. Prec ision of source coun , P. :

2. Prec ision o f standard count, ~ :

3. E ror due to b c ground, el:

RE= \je~

c) To al 'Er or TE: SE NOTES

( XI Th e error given is calculated a t e '7 '? % confidence I cl.

( ) T his callbra ion is directly/ indire ly based on BS Standard Refe renc Material No.

~ . ,,,

i a l h P hy i c l. => l.

148

Calibration records

- Manufacturer provided licensees a "Calibration Summary Report" on both:

the "ProtoType" detector calibration, and

the "Production" detector 1s calibration

Calibration Summary Report

Report Number 1111111_ _ _. . . summary Report of Area Radiation Monitoring System Detector Calibration

Report Number 11ia1----

Corporation Report of Calibration, Model KDA-HR, High Range Area Monitor Ion Chamber Detector.

Master Material Equipment List and Shipping Documentation, dated 7/3/85, with one Cs-137 source of 96.4 mCi, with traceability Numbers 7605-1, Cs-1498.

_..__ Certificate of Calibration for Source with Serial Number CS1498, dated 1/14/83.

150

Step 4 In-Plant Calibrations

Calibration Check

Objective

- Determine if the CHRM is operating correctly

Method:

- Perform electronic calibration check

- Perform radiation detector check

by comparing detector response to manufacturer's decay corrected, expected value \

152 *~ U.S.NRC Proft'd1'1g l'roplr ,uul r/,,* F,u,,ron,,,ott

Example:

Plant's Acceptance Test

1986- Manufacturer shipped the CHRM and field calibrator with Cs-137 source with NBS traceable certificate

Ideally, upon receipt of CHRMs equipment from the vendor, the licensees should do an acceptance test.

- Licensees first use the Field Calibrator and perform a calibration check and compare dose rate reading to a known "expected" value given by the manufacturer (decay corrected)

- Licensees may have documentation on the initial acceptance test (before installation) 153

Experience with Typical Radiation Detectors

Plant staff performed an in-plant calibration check on the CHRM and verified proper operation by:

- Exposing the CHRM to the calibration source in the Field Calibrator and verifying the transfer dose-rate value of 7.72 R/hr (as decayed to current date)

- Plant staff concerns were raised about integrity of the mineral insulation cabling while removing the CHRM from its wall mount

\

154 *~ U.S.NRC f*,*ott"l"frll_f!, /h,pfr iutr/ ti,,. F ,,,.,ro'1mt1I

In-plant Calibration

In-plant licensee calibrations then use the Field Calibrator and compare the CHRMs readings to the expected response value (e.g., ,v7.72 R/hr)

(after decay correction)

The ANSI N323-1979 accuracy criteria is tt 40%,

i.e., the acceptable range= 7.72 R/hr +/- 40%

= 4.6 R/hr to 10.8 R/hr

The IEEE 497-2017 accuracy criteria is+/- 50%

= 3.86 R/hr to 11.6 R/hr 155

Example of Documentation of Installation of CHRM Th,"::, - '.3'" c.1'.aY\.3 ca. I \s -Q:,..- h

+

1

, "s-kt lla:-kc, c--f. C lets s. 1 E. un da '"--

s a.+- +i h, 5 h. ro.~:ie., 10 ° +c 10 8 R/1,s _

~Or\+c:t"tt.m-e, + ar Q r d~a...+,on fnCl\,-t-or:s a-s ~ ' d by /\,' ct REG 05 7&>. m(g_ s 1 sl-e1"\

eo,s ,'".::>U\-s ~ ~de S rr- <:t.d C<.e ModuJ~_ a. Vld. ca.bl 3 Ar E?a.c. +ruin. .

Tl-\'E.. sys ~ .m -6 a. I I h ~1-t<i rn~T\.-h.

~ f\JU'2.EE, 05,d and -su..bs iu.. 1 :-f r~rdre~

Ynef\+s .

T..-a,n.s Ti NUREG-0578 {July 1979) TMl-2 LLTF 156 Short Term Recommendations

Documentation of Installation of CHRM

'E'1'\'e+ +, n.s A- 0 w cf h. h qck1lt+

~c.d , "' ~r-- ZJ?:tf 'l and I 12-1.tq b-e 1 ~

11~ _ " p:,*:wh-~ "S IVJ a f\J cf1 "t

11'\-s RMS g C. -z. ~-2. f""e. p C. 1/'f.'. Trt:t I Ir\

B rn *. "1-M rs,. IR- 1.1 an.d z '2 lf8 u.s '

p. n 1

-..i-.c-,. -H ," D II w , ,I h ~do<.L med uJ s b

j he l. E! d 1 " ' , ~ t--1-ro t"IS M Ctnd N £M * '2 _c.k IRM-Z

~-e 11-ely, 157

Documentation of Installation of D~4cl*or lf-s:s.1E-,11'\. .by

- -~~=..:::...J~...,u..JJ,- ~-~, . f\ b yi

. . 1 1 s ct. Sfl Jnn,Gt s-ens 1

-H ~ ,o ~ eha.*'Y\ b~\,.. -er"tCa.s r;~ , "'

sfa.11 te.S..-s. s..f..e<;>/, The. c +edor par+

ei-f- .+h Q"5s-Prn. ly ~ CL cy Ifl'\. -er w ,'-f..l,

.a _ th" ' h,c:k. I tan ~-+ t- a1td n l'"f\ e_

t'\C I. /v.;. *'f'f

Tit-e. pu. I be,)<.. ~ cl--t-o, c,f- h. d +c.-tor a~5 m.hly . '<!. (\, n tr\ck~":'> h ~h by . iou.v--- tl'\.c.hl?'S *-u tel by

-Po* r-- r r-..c.'K-es :.:1 -ep. Th~ d eda ""'

ca bf J l?oc lcb"(,'s--b Mocl-e I Q<s"S-Mo</ Is hamf wtre.d 1 +h,e pu..11 bo')(_ ai,d J

r~ m ,u_f d 1/4 +h~ C&r\1-o. ,,rn:ef\..+

158 p't?(\~+ru.+tcr1.

Documentation of Installation of CHRM

.4 l ~u..\'""' d-ek<..4o~ CLSS~rY\bh-es are. i-ncu.,'\{ed 61'"\ z z. '/z. . ln.cl, h \51-\

5~~,as rnctn1.A.-1/4:u:-fured ~ QA- Type l st--e~ I. U.N\; -\- I *rro. ~ A: d -e. <..-lo G Je-4 'I i

\"c> lo m.-1-ed on. fl,.e. <55 {'/-e,u~ of ,

+k-e. mnk,h rn-eiJ- a.+- c.o rdM,Q.4-es Y6° Mld 5/p' +ren'\. c.on+a,n rAe ,d-- c~ ,-rler-,

Ll;n,+ I Tm.H'\ B d +-ec..tor:, jQ-ll~ 1 15 Io ca+e d o I'"\ -e l-e ~rccl-i-e-r, 7 -5 5 cti +- h c0t1+a. j"l') f"I'\'{' I\_+ a...+- C...0 C-,f',:h,'\,Q.-f-es 28-Z. C CVV\d 5~ -P'e'e+ +'rol'Y"\ eoY\-f.a,n me,,-.J- e.et'l-ter.

l~ ~+- Z. Tt"-Ct 11-*, ,4 d-e.+ec.4cr 1 z f?-L/q 0

)oca.+ed or\ el'~a.+lol'\ -t55 o-f +ft'..

ccn+a"""',ef\..+ a..+ co ordu, a+es

-Pe~+

""350c w"d.- 5/o ~ --c.'l'Y'\. con iuih r\'\'e,d-ce,t~I'\

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71) ~ h, I\ *""<'I~ .'. an, d s 'Jnal c_ah t-es 1 - - - - - - - - - -

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161

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~ b {-0 r""S n'(l_ d .. ~ a.d d fo To.bit FSAR Table 7.7-2 7, 7-Z.. ' Po-s /'.b:,d I\,+ .

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Il b~ avail bl ia v-- Q.I( * 'fyp *.J a+. ~J * ~\ I cttl Qc 'd,~ (1 .f..ed, 162

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163

Electronic Calibration

Electronic Calibration

- The detector (ion chamber) output is electrica l current; measured in amps (an analog signal)

- The electronic calibration tests the Analog to Digital Converter by using a pico-amp generator and observing the microprocessor readouts 164

~' U.S.N R(~

! 1rotntmg l'rop/r 1111d ti,,, /-'1nrm1mr11t

Alarm Setpoints

Each detector has 2 or more electronic "Channels"

Plant staff choose Alarm Setpoints:

Setpoints are normally set well below Emergency Action Level thresholds. Examples are:

- ALERT Alarms

Channel 1 at 100 R/hr

Channel 2 at 10 R/hr

- HIGH Alarm

Channel 1 at 1,000 R/hr

Channel 2 at 2,000 R/hr 165

Example Field Calibration Method

Take the Field Calibrator to the CHRMs

Mount the Field Calibrator onto the CHRMs (see photo on next slide)

Take readings and compare to decayed corrected expected readings i

166

~ U.S.NRC

! 1rolt"dt11g /'roplr ,uul ti,,. F m rrm1mr11t

CHRMs B 1 - 1 _ --

~--- ....

_ ....._ .............~

The** - - 1gh-range in-containment area (HRICA) detec~ors (drawing 609209&) calibrated at the

- - - - 111111111111!MMI Q 7 I detect activity rn the range of l O to l O R/hr over an energy range of 80 l<:.ev to 3 MeV. The detectors are Qua 1 if ed to funct \.on durfog and after a loss-of-coolan accident ( LOCA). Maximum accident temperature is 400°F, and maximum accident pressure ts 50 psig .

B-8-2 TRACEABILITY AND STANDARDIZATION The high level f"eld strength tests were run at Argonne National l aboratory using its 60 co mu 1ti point field. This field has a standardized strength as detenni nea by an NBS ganma ion chamber (model RS-C4-l &06-2'0 3}.

Table 8 lists the ~tandardized fields and locattons.

TABLE 8-8-1. STANDARDIZED F[ELD AS A FUNCTION Of LOCATION un Location Dose Rate (R/hr) 61 I Ea*s t 1 .09 X 104 2 center 1 . 34 x 10b 3 1 I East 6 . 20 x 105 8-8 2 Detector Energy Response To cover as wide an enenJy range a possib l e, m asure ents were made wi th 168 four i sotopes ,( co, 57 133 ea. 3

'cs. and 60 co)

These i s.otopes cover energ *es between 0 .122 and 1. 25 MeV. These sourc~s were of low field

Dose Rate Linearity Test CAUBRA1 [O N OAT

/

I/

/

/ '

CORM Sensitivity & Accuracy CALlB AliON OATA TA BLE 8 4 . SE SI Tl llY EA~UREMENT RESULTS USING THE ION CHAMBER Ener-gy Avera9e I ncremental Rad i ation Source Leve Cur-rent Curr-ent Field Sens it fv i ty (MeV) no- 11 A) (l o-11 A) (mR/hr) ( lo - 11 A/R/hr) 57co 0. 122 l . 211 4 0 . 0011 0 . 01 24 ! 0. 001 7 1 1. 3 l . 09 +- 0. 13 133ea 0.356 1.457 .t 0.0014 0.258 .t 0.002 245 . 0 l . 05 .t O*008 l37cs 0.6&2 1.245 .t 0.002 0 .046 .t 0.0024 45 . 2 1 .02 !: 0.053 60c_o l. 17 1.279 .!: 0.0014 0 . 080 .t 0.002 77. 3 1.03 .!: 0.025

l. 33 No Source 1.1 99 .t 0 . 0014 B 4 ACC URACY he ac.cu r.ac y components of he h1 gh - range n-conta i nme nt area detector we re as fo 11 OWS :

1. alibration accuracy

2. urrent-measuring accuracy

3. Oetector re eatabil'ty

4. Iso ope esponse accuracy .

Assuming a calibration ie ld accuracy o Si and current -measuring accurac i es of 2%, the tota c alibration accuracy is 71. w*th the detector 170 repeatabili y a 20% and isotope ace racy of 201, he overall detector .NRC accuracy is 28%. dnd r/,,* J 1,, .,,*m,,,1t*"t

Example: FSAR G. Containment High Range Area Monitors RE-0005 and RE-0006 To ind icate along with RE-0002 and RE-0003 the rad iation levels inside the containment building at the operating deck following a design basis accident.

- *-FSAR-12 TABLE 12.3.4-2 (SHEET 1 OF 2)

RANGE AND CONTROL FUNCTIONS FOR AREA RADIATION MON ITORS Range Sensitivity Monitor (mR/h) (mR/h) Control Function Accuracy RE-0005 RE-0006 (A 103 to 1011 (both) No _ 20 percent of actual and B) containment high radiation field range 171

Violation - White Finding

NRC issued a White finding for invalid calibration and invalid adjustment of CHRMs output

Apparent cause: A CHRMs system was manufactured and sold without supplying a Field Calibrator

The plant purchased a Field Calibrator from a different vendor

The Field Calibrator was not designed for CHRM calibration

Plant incorrectly developed their own calibration method

Then used a tripod mount to hold the Cs-137 source closer to the detector 172

White Finding (cont.)

- Plant calibration method was based on a calibration laboratory measurements using a Condenser R chamber to determine the expected 11 value" at a point" at a specific distance 11

- The expected value" was determined incorrectly, 11 with 3 sources of error (see next slide):

White Finding (cont.)

Three sources of error occurred:

1. Detector "volume" errors in determining the "expected value" (i.e., dose rate)

A Condenser R chamber {0.6 cm 3 small volume)

("' essentially a point measurement)

CHRMs ion chamber has a 130 cm 3 (large volume)

("' a volumetric measurement)

2. Geometry errors

As the source decayed, the source was pushed closer to the detector to achieve 174 the desired "expected value"

White Finding (cont.)

( third error)

3. Plant staff error:

As the source was moved closer to the CHRMs, the CHRMs did not display the "correct,, expected value, so plant staff incorrectly adjusted the gain on the CHRMs to achieve the expected value

Other Inspection Experiences

A Field Calibrator was not locked properly when stored, source could have been removed

Locking pins were found to be missing from the Field Calibrator and were replaced with pieces of wire

Other Considerations

The Field Calibrator with Cs-137 source was licensed under 10 CFR 30

The Field Calibrator must be used and maintained in that licensed configuration

Repairs must be made by the original vendor or someone authorized under the 10 CFR 30 license to work on these sources.

The vendor might authorize these, by letter, since repairs could be very simple.

177

Inspection Experiences

A Field Calibrator was replaced with different model (but retained the old model number)

New calibration data was provided by vendor applicable to a different model of rad monitor (i.e.,

for the post-Fukushima hardened vent monitor)

Calibration data was not applicable to CHRMs, resulting in calibration error 178

Example: In-Plant Calibration Procedure 5.2 Calilb r atio ~ n The 1monitoring systems requi e calibratiion befor,e placing tihem into service. l n add1tion *r tiey should be recalibrated at regu:lar interva1s during routine service. The length of time between calibration interva'ls sho'Uld be determined by operations personnet Fo further calibration information, refer to the applicable calibration procedure provided *in Appendix A.

- - - - llf"lant.

The high-range containment area monitor unde rwent a complete electronic and isotopic calibration prior 1

to leaving the The same electronic calibration procedure is s uppl*ied in this manual. Prior o pnmary 1so op1c calibration, the detector*s hermetically 1m ust be verified. Primary isotopic calibration requires a highly radioactive source (greater than 400 curies w*th National Bureau of Standards (NBS) traceability. As this is beyond the capabi ity of most facihties to pe *orm the foUowing method of v,e nfying detector ca.lib afon i s used:

Detectors shall either be returned to -.t a five (5) year *nterval from the date of dehv,e ry or the owner must estabhsh a procedure to determine that the .average AIR/h output current does not deviate from ,01:iginal factory cahbr.ation by mor,e than = 10°/o.

To encompass Nureg-0737 guidelines on -site in-situ calibration checks can be performed with the ii.ii.iii High-Range Field Calibrator th at is capable of producing a 10 R/h indication on the channel under test.I 179

Field Calibrator CHRMs s.wc..P.c-, ... , ,. ..

P/N 8]8- 10 ERT.JnCATE OF .CALIBRATION

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nd.* ls available *for **~~r. revt ew.

8-10 calfbratcr Sedal Nu111ber 106 A/ti July 24, 1984

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180

Unmounting CHRMs for calibration

Some plants physically unmount (remove)

CHRMs from installed locations

Then perform a calibration in a box calibrator

Module 5 Inspector Preparations And Experiences

Inspector Preparations

FSAR - Review the FSAR to obtain plant-specific description of CHRMs

Tech Specs -

- Review plant-specific STS for definitions of Channel Check and Channel Calibration

- Review Post-Accident Monitoring Instrumentation (e.g., TS 3. 3. 3)

- Review TS 5.4.1 for Emergency Operating Procedure criteria 183

Inspector Preparation

Review EPRI proprietary report, "Calibration of Radiation Monitors," Rev. 2, (ML21146A265)

Review licensee Emergency Planning documents to determine which Radiation Monitors are tied to EOPs and EALs

Review licensee's Post-TMI commitments and Orders

Review work orders/surveillance procedures for most recent CHRMs calibrations

'i 184

~ U.S.NRC l 1roft*lf111_'( /h ,p/r .11,tl ti,,. l nr *rrrmmr,,t

Inspector Preparation

Request and review CHRMs system manuals

Request and review licensee calibration procedures

Determine the calibration method

- Vendor Field Calibrator?

- Home Made Field Calibrator?

If home-made calibrator, review the technical bases for the new Field Calibrator method

\

185 *~ U.S.NRC

/Jmut1111g l'roplr ,uul r/,,. fn11rm1m,*11t

Inspector Preparations

Review most recent radiological calibration checks

Review electronic calibrations

Determine if the licensee adjusted any CHRMs calibration constants, and if so, determine why?

186

Calibration Acceptance Criteria

- Determine calibration accuracy criteria, should be either:

+ 40% per ANSI N320-1979, or

+ 50% per IEEE 497-2017

- Some sites may be incorrectly using an accuracy criteria of a "factor of 2," based on the footnote in RG 1.97, Rev. 2 or Rev. 3

- Note: The "factor of 2" is not a calibration criteria.

It is an "instrument design criteria" for detector's energy response 187 from 80 keV to 3 MeV

Inspector Preparation

Maintenance history

- Review the maintenance history on the CHRMs

- Review any component failures and replacements

- Determine if there has there been failures of cabling mineral insulation, and if so, has it been replaced or is it a continuing problem?

188

Home-made Field Calibration Jigs What's the problem?

Normally, the manufacturer does a calibration of its CHRM in its own Field Calibrator using a NIST traceable source

Home-made Field Calibrators - what's the problem?

- How was the expected response determined?

- How does the plant know if the CHRM detector was operating properly when the expected response measurement was made?

- Does the plant have an evaluation of the calibration of its own home-made field calibrator?

189

Home-Made Field Calibrators

Plants should have a documented evaluation of the expected dose rate from the source in a home-made Field Calibrator

Dose rates obtained from NIST-source certificates cannot be used directly by inverse square law, since these are dose rates at "point" locations vs a "volumetric" detector's geometry

The inverse square law does not work because of geometry differences 190

Replacement Sources

Most original Cs-137 sources have now decayed over 50%

Dose rates have declined toward the lower end of the 1 R/hr to 10 R/hr scale

Some plants may have replaced their sources

A NIST traceable source can be used

How was "expected value" determined?

Review EPRI proprietary report, "Calibration of Radiation Monitors, Rev. 2, (ML21146A265}

11 191

Example I - Source Replacement How to determine "expected response"

The "expected response" can be based on the ratio of the activity of the NIST traceable Cs-137 sources

Example: The original NIST source was 110 mCi producing a 7.72 R/hr dose rate in the Field Calibrator Jig

Replacement source is 120 mCi.

By ratio, the new "expected response" is

= 120 / 110 x 7.72 R/hr = 8.42 R/hr 192

Example 2: Home-made Field Calibrator Developing a new expected response value

First, verify the CHRM was operating properly (e.g.,

by using the original Field Calibrator)

Expose the CHRM to the replacement source in the home-made Field Calibrator jig to determine its new "expected response"

Use the new "expected response" value (decayed for future calibration checks) 193

Example #3 Trans£er Standard using Cutie Pie

A Field Calibrator was no longer used

A licensee developed their own Transfer Standard using a Cutie Pie dose rate meter

Issue of Concern: Was an evaluation of equivalency performed?

194

Example #3 ( continued)

Transfer Standard using Cutie Pie

Used a 2nd Transfer detector that has been recently calibrated (e.g., a Cutie Pie)

Used the home-made Field Calibrator with its Cs-137 source, measure the dose rate on the Cutie Pie to determine the "Expected Response,,

Exposed the CHRM to the same source in the same geometry

Determined if the CHRM response was the same as the 2 nd transfer detector 195

Cutie Pie 7 40F Calibration

Cutie Pie has decade selector switches

X1,x10,x100,x1000

0- 25 mR/hr, 0 - 250 mR/hr, 0 - 2,500 mR/hr and 0 - 25,000 mR/hr

.2 CaHbratiion of the Cute Pie Mode, No. 740F 8.2.1 From fhe curren Calibration Curves or Exposure Ra e a les, determine the sources, distance and attenuation factors, rr applicable required to deliver do~e ra es at 20% and 80~/o of fun scale desired dose rates for each range or a specffied: by Supervi or lnstrumen *Ca ibration SIC or 196

Concerns with Use of Cutie Pie as a Transfer Standard

Cutie Pie was calibrated to Cs-137 within one week

Geometry of transfer calibration was not specified

Possibly calibrated in a box calibrator 197

Module 6 Licensee Calibration Procedures

Excerpts from Plant Procedures Example I 4.0 PERSONNEL AND SPECIAL EQUIPMENT REQUIREMENTS 4.1 Two (2)Radiation Protection Personnel Required 4.2 One (1) Licensed Operator ~

4.3 200 mCi Cesium 137 Source t..ll ~ll\ ~

4.4 200 me, Bugging Tool (i.e., FiEWd Calibrator) 4.5 Long Handled Source Tool

Excerpts from Plant Procedures Example I 6.0 E QUISITES A l D INlTIAL CONiD ITIONS PIR ER1 1

__ t,/'4llf ~/11,/!1

,&.1 Veirify that SP 1783.4A and Sp 1183.48 have be,en comple*ied.

6. 2 Obtain the desired readings from the Radiation Monitoring Database RADMON.MDBh and enter in the note sections for each monitor.

6. 3 P,erform independent verfficaUon ,of va ues, entered.

1 6.4 Co,n duct a Pre-Job IB nief 1

6. 5 Notify the Control R,oom Operators to, expec various Rad Monitor related annunciators to allarm during thrs test.

6.6 ,Q bta1 1n Sh"ift Supervisor s permission to, perform: test.

200

Excerpts from Plant Procedures Example I (Detector IR-48) 7 .1 1IR-48, Unit 1 Containment High Range Area Radiation Monitor 7.1.1 Note the background level.

Bug= expose 7.1 .2 When notified by RP in Containment that they ar,e ready to bug 1 R-48 , bug the detector and note the date. time.

and all meter readings for the two bug points.

7 .1 .3 After all bug points have been recorded , direct RP in Containment to put the protective cover back in place.

7.1.4 Rotate the *O PERATE switch to the "CH ECK" position.

7 .1.5 Note the meter reading jn the note sectio:n .

NOTES

' Monitor Bug Point Background Low Corrected High Limit Date Tlme Lim it Readin 1 / .,Y°~d 7.6e-1 ~ c) 6.1e0 2 /-f'D

Data Analysis Example I ( detector IR-48)

NOTES Monitor Bug Point Background Low Corrected High Limit . Date Time Limit Reading 1 / .rt;:"" 7.6e-1 9'Ec) 6.1e0 7#, ft /6/iJ

What is a "corrected reading"? Is that the measured value or the expected value?

Inspectors should look at the Low and High Limits (acceptance criteria)

Why are the values typed in?

- Are the values decay corrected?

- Why is the low/high acceptance range so large?

from 0.76to 6.1 R/hr?

vs. 4.0 + 40% would be a range of 2.4 to 5.6 1 202 *~ U.S.NRC

/'rolt'dtng l'rop/,* ,uul r/,,. J ,,, r,*mrm,*'1f

More Data Analysis Example I ( monitor IR-48)

NOTES Monitor Bug Point Background Low Corrected High Limit ; Date Time Limit Read in Low Side? 1 / .5'/F" 7.6e-1 ~ cJ 6 .1 e0 High Side? 2

/ .fE' D 1R-48

- How can the Low Limit be 2.0E4 (20 R/hr?)

- How can the High Limit be 1.6e5 (160 R/hr?)

- Is that on contact with the Field Calibrator?

- How is that measured?

- Is the data for the check source in mR/hr?

203

Plant Calibration Example 2 (monitor IR-49) 7.3 1R-49, Unit 1 Containment High Range Area Radiation Monitor 7.3.1 Note the background level.

7.3.2 When notified by RP 1in Containment that they are r,e ady to bug 1 R-4'9 , bug the detector and note the date, time, and all meter readings for the tw,o bug points.

7.3.3 Rotate the OPERATE switch to the 'CHIECK' position.

1 7.3.4 Note the meter read1ing in the note section .

NOTES Monitor Bug Po:i nt : !B ackground Low Corrected 'High Limit , Date I Time Limit Readin 1 1.1e0 8.BeO 2

Data Analysis Example 2 (monitor lR-49)

NOTES Monitor

Bug Point :B ackground Low Corrected High Limit 1Date Time Limit Read in.

1.1 e0 Source d

Why are the Low and High Limits different than for the detector lR-49 ?

Possible Answer: Because the internal background on CHRMs # lR-48 was 1.5 R/hr vs. lR-49 was 2 R/hr

'i 205

~ U.S.NRC f*rottYltng l'rop/,* ,uu/ rlw F m rrrmm,*rlf

Plant Calibration Example 3 7.2 2R-48, Unit 2 Containment High Range Area Radiation Monitor 7.2.1 Note the background level.

7.2.2 When notified by RP in Containment that they are ready "B ,,

to bug 2R-48, bug the detector and note the date, time , _

U_____ ~ _a_n_S expose and all meter readings for the two bug points.

7.2.3 After all bug points have been recorded, direct RP in Containment to put the protective cover back in place .

7.2.4 Rotate the OPERATE switch to the .. CHECK" position.

7.2.5 Note the meter reading in the note section .

NOTES Monitor Bug Point Background Low Corrected High Lim jt Date Time Limit Readin 1 /.ft 0 i 7.1e0 2R48 2 /.YE 0

Calibration Procedure Example 4 1.0 PURPOSE 1.1.1 Sections 4 .5 and 4 .1o can only be performed when plant conditions allow entrance into the Reactor Building such as during an outage. The rema inder of the procedure is normally performed re-out age.

1.1.2 Calibrate RM -G29 and RM-G30 with Pico-Am p source simulating a detector signa l.

1.1.3 Calibrate/verify all end oint readout locations (recorder, recall points, REDAS points) using Pico-Amp source.

1.1.4 Verify readout monitor alarms and REDAS alarms from loss of ower, loss of sig nal. high radiation , C heck switch osition, and Trip adjust switch position 1.1.5 Provide a detector operability check by utilizing a known gamma sou rce at the ionization chamber and verifying equivalent dose rate at the readout module .

2. 1.2 Instruction Ma nuals:

Manua l #506, High Ra nge Gamma Rad iation Monitoring System 2.1.3 M AR s:

MAR 86- 10-06-01 , and 86- 10-06-01 , MAR f unctional Test TP-18

MAR 82-05-03-07 , FC N 8 and 82-05-03-07 MAR Functional Test TP-3A

MA R 82-05 12, FCN 18, FCN 20 , an d FCN 21

MAR 88-06-07-0 , New Power Sup ply Breaker for RM -G 29/30 207

Technical Specifications 2.1.4 Techn',cal Specificatiion !R e*fe rences NOCS 000998)

LCO /Other Applicable Surv. Perf. Requirement s Surv. Fre*q.

R,eferences During Modes D uni:ng IM odes Freq . Notes 1 t hru 6 ,

3.3.17 .2 (1 1) 1, 2 3 2Y and NO Mode

2Y at least onc*e per 24 mont:hs

Exainple Licensee Coininitinents

2. 1.5 NOCS Commitments 000998, 001783, 005825 . 060310. and 090210 2.1 .6 Cale. 189-0006 . IR and Loop Uncertain Rad Monitors RM-G29 and RM-G30

Example Calibration Procedure 4.0 INSTRUCTIONS NOTE Pico ammeter input values are based on detector coefficient of 1.04 . If a detector is replaced a procedu re revision will be requ ired .

4.1 RM -G29 Calibration and Functional Test 4.1. 1 NOTIFY SM/CRS ITS 3.3.17 Condition A will be entered ........... .............. .. .. ................ ........

4.1 .2 NOTIFY Nuclear Operator of alarms during this test:

Annunciator H-1-1, GAMMA RAD IATION HIGH ......................... ............... ... ............ ....... ..

Annunciator H-1-2, GAMMA MONITO,R WA:RN ING ......... ... ....... ..... .......... .......... .. ............

E}lent Point 1784 ..... ... ......... ........ ... ..... .... ........ ... ..... ................. ... ............. ............. .............. 0

Event Point 1785 .... ...... ... .......... ............. ... ......... ... ....... ....... .......... .... ............. ...... .. ............

PICS REDAS Points W049 ........ ....... ... ...... ...... ...... ....... ..... ......... ..... .. .. .. ......... ....... ... ..........0

PICS REDAS Points W050 .. ..... ... ........ .... .......... ... ............ ....... ... ............... ........ .. ............ ..

4.1 .3 MEASURE ambient temperature at calibration location and RECORD on Enclosure 1, RM-G29 Data Sheet.. .... .......... ..................... ... .... ... ... ... .. ................

210

Example Electronic Calibration 4 .2 Electronic Calibration Adj ustment of RM-G29 4 .2.1 Concurrent Ve rification Point OP:E N !links to deenergize rate meter:

Rt11f.emeter *: .* ,:1;1n $

.. : I*e ~erf<<?:tme:d,by. Concu rent ...

~ ierifloatlon

" " lnJt lallDat:e

RM-G29 TB 17- 17 RM -G2*9 T B 17-1,8 4.2.2 DISCONNiECT Pico Amp current s-ource at sig nal in put. .. .... ............. ..... .... ........ ...... ...... ... .....

4.2.3 CONNECT DM M to input coaxia l cable of ratemeter to measure input off-set voltage . .. .... .......... .. ....... .. ... ........ ........ ..... ......... .... ... .......... ...... .... ..... .. ......... .. .. ........ .O 4..2 .4 Concurrent Verification Point E N E RG I.ZIE ratemeter by closing links, and WAIT five minutes for warmup:

P,e fot'JJI~ b'y* COJ'! CUrr.-nt R tem eter: .. .f.. nks lniba-UCl*at-e " :

Verlific:nr:t,oni. :

IRM-G29 TB 17-17 RM-G29 TB 17-18

Adjust meter readout to IR/hr (based on pico-amp input) 4.2.9 RECONNECT Pico-Amp source to the input coaxial cable ................................ ..................... 0 4.2.10 ADJUST mechanical meter zero (side of meter) for a reading of 10° R/Hr .......................................................... ............. ............................................................. .

4.2.11 Concurrent Verification Point CLOSE links to ENERGIZE ratemeter and WAIT five minutes for wa~mup:

PRFORMEO BY: C*ONCURRENT RATEMETER l 1NKS

! .. * -~-- .. . .... INITIAL/PATE .. VERiFIC,A TION RM-G29 TB 17-17 RM~G29 TB 17~18 4.2.12 ADJUST Pico-Am source to in ut 1.04 x 10*5 am s........ ......................................................

4.2.13 ADJUST Slope Adj pot for a TP-3 voltage reading of 7.50 VDC (7.20 to 7.80 VDC).......................................................................................... ............. ............ 0 212

Adjust meter readout to I million R/hr (based on pico-amp input) 4.2.14 ADJUST Pico-Amp source to 1.04 x 10*9 amps.

4.2.15 ADJUST Bias Adj pot for a TP-3 voltage of 2.so voe (2.20 to 2.80) . .. .. ........ ..... ... ..... ....... .. ................. ......................... ... ............. ... .... .. ... ..

4.2.16 REPEAT 4.2 .12 thro ugh 4 .2.15 until r*eadings are in tolerance and RECORD fin al values:

FINAL BIAS ADJ RATEMETER F INAL S LOPE AD J READING IN JTIA L/OATE READING .

RM -G29 4.2.17 ADJUST Pico-Amp source to appty 1.04 x 10*5 amps to ratemeter ... .... ....... ... ... .............. .......

4.2.18 ADJUST Meter Adj pot for a meter reading of 1 x 106 R/Hr.... ... ............... .... ... ... .. .. .. ... ... ....... ..0

Example: Check alarm setpoints 4.3 RM-G29 As-Left Calibration Data CAUTION When power is app!lied to the readout module , the circuits ,g enerate high vo ltages (up to 1000 V) . Failure to de-ener,glze the unit before making. connections can resu lt in equipment damage and electrical shock.

4.3.1 INPU T current signals from cal data sheet and RECORD As Left data . ... ..... ............... .......... ... ..... .............. ... ........................ ....... ... .... .. ....... ................................

9 4.3.2 ADJUST Pico-Amp source current input to 0 .01 X 10* and RESET ratemeter alarms .............. ..... ... ..... .. ...... .. ... .. .. .. ...... .. ... ...... ... .. ........ ... -.. -.. .-..-..-..-.. -.. -.. .-..-..-.. -...-..-..-..-.. -.... 0 4.3.3 RAISE input current until t he Trip 1 light is ON ........ ... ......... ... .. ........ ..... ....... ... ... ....... .... ........ .. 0 4.3.4 RECORD Input current , output voltage, and monitor display for As Left Warning setpo int:

tNPU T CURRENT OUTPUT@ TP-3 MONITOR DISPLAY RATEMETER Amps voe (analo,a_metel'.) R/HR DESIRED 0.832 X 10** to 1.25 x 10.. 2.2 to 2.8 80 to 141 VALUcS Amps voe RIHRj RM-G29 214

Example: Check Alarm Failure 4.4 Functional Check of RM-G29 Failure and Switch Alarms 4.4.1 Concurrent Ver flcatlon Point OPEN links to deen,ergize rate meter:

Performed By: Concurrent RATEMETER Lmks }

lnltlal.lOate Verification RM-G29 TB 17-1 7 RM -G29 TB 17- 18 4.4.2 VER IFY associated REOAS point has faile~:

Ratemeter REDAS p o i nt Cond ition Initial/Date RM-G29 W049 (YIES) FAILED

Example: Calibration Procedure

The following slides appear to be l&C procedure

Where is the Chemistry/HP Procedure?

- Does the procedure describe how to determine the expected value?

- Does the procedure describe how to use the Field Calibrator to achieve the correct exposure geometry?

216

Exan1ple: Radiation Calibration Check Note: This appears to he an I&C procedure 4.5 .6 REQUEST HP to EXPOSE detector to a Gamma Field of between 3 and 10 R/Hr:

RATEMETER " KNOWN GAMMA FIELD VALUE 1,N1'.JlAL/DATE RMsG29 R/Hr 4.5.7 REC,ORD IDMIM reading at TP-3 when t~e detector ionizaron chamber under test is exposed to the source :

RA:TEMETE'R .. ...

, r ,,:.;.:

.:*~. ~~

DMM. REA.DJNCJ voe

......., . INITFAL/DATE

-~

voe RM!-G29 4.5 .8 CONVERT DMM reading to an equiva lent R/Hr dose rate as foUows:

1. DIVtDE voltage reading by 1.25 to det erm ine the log base 10 ... .. ...... ....... .. .

2. Raise ten (10) to the power of V/1.25 (10"' 1 *25) ..... ...... .................. ............... .

This w ill yield equiva:rent dose rate.

Example: Assume the DMM reading was 0.95 voe 0.95/ 1.25 = 0.76

10. 0

6 = 5.75 R/Hr equiivalenl dose rate OR 10 ,,11 .2s = 110,0,-9 1.2 = 100.1s = 5 .7 S R/H r .NRC

roucrrng / 'rop ,* ,uul rl,,* / ,,, ,ronmoJt

Example: Subtract Background 4.5.9 lndepe.ndent Verifi.cation Point REC ORD vo tt ag*e converted to R/Hr calcu late d value:

,SQU IVALENT .

INOEPENOENTL Y CALCU1.ATIO N :PERFOR MED RATEMETeR -CALCULATED VERIFIED BY BY: INITIAU OATE '

VALUE RJHR ;:

INITIALJOA TE RM ""G29 4.5.10 SUBTRACT the background reading Recorded in step 4 .5.5 from the Sou rce reading recorded in step 4.5.9 to determine Calcu lated Actua l Readin and RECORD:

Source Reading - Background Reading = Calculated Actual Reading _ _ _ _ _ R/Hr 4.5.11 IF Calculated Actual Reading R/Hr dose rate does NOT agree within the following acceptance criteria statement, THEN REFER TO Section 5.2, Contingencies .. .. .. .. ... .... .... .. .. ...... ....... .......... .. ........ .......... .

Functional Test, with Radiation Source, ACCEPTANC E CRITERIA .. .... .... ... ........ ..... ....... .. .... ......... .. ....... ...... ....... .. .... ......... ....... ............ ...... ... .... ...

I RATEMETER RM-G29 I

Calculated Actual Value is equal to the field strengt h +/-20% :

.E~ROR I II 218

Example: Follow-up Questions 4.5 .6 REQUEST HP to EXPOSE detector to a Gamma Fie ld of between 3 and 1a R/Hr:

R-ATEMETER C KMOWN GAMMA FIELD .VALUE INll'lAL1DATE RMI-G29 R/Hr

What was the calibration geometry?

Did the vendor specify how the field calibration geometry was to be established?

What was the expected value?

Was there a Field Calibrator?

Was the expected value decay corrected?

219

Exampe: Self Assessments

After learning of an industry White finding on mis-calibration of CHRMs, the plant staff did a self-assessment

Self-assessment was inadequate, i.e., did not recognize or investigate the geometry change

A Condition Report was written that the dose rate and date used in the calibration procedure did not match the information on the radiation source certificate

The inspector reviewed the CR and recognized that there had been an inappropriate change in the calibration geometry 220

Other examples: Radiation Detectors

In order to protect cabling, the calibration geometry was changed

Instead of removing the detector from its wall mount, the Cs-137 source was placed against the detector in a new geometry

A new transfer standard was developed of 8.06 R/hr

+/- 0.364 R/hr

The acceptance criteria for the calibration check was +/- 20% (vs. 40%)

221

Example: Radiation Detectors

A Field Change Request was attached to a CAP Condition Report (CR) to change the calibration geometry

The inspector questioned the change in the geometry for the secondary/transfer calibration method being used

How was the new transfer standard established?

Was the new transfer standard NIST traceable?

222

Module 7 References

Main Reports on TMl-2 Accident

NRC staff (l&E) technical report

- NUREG-0600 (ML090050311)

- Radiological Aspects of TMl-2 Accident

pgs 13 - 21 (pdf pgs 31 - 39)

Appendix II (Details on document pg II -1 to 11-E-6 or pdf pgs 438 -

779

Rasmussen Reactor Safety Study

- NUREG-075/014 WASH-1400 (1975)

- Search on NRC Public Web site search

Kemeny Report to the President's Commission, Vol. I and II

- Search for it on Google 224

NRC Requireinents following TMI-2 accident

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