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NRC INSPECTION MANUAL DI

INSPECTION PROCEDURE 61705

CALIBRATION OF NUCLEAR INSTRUMENTATION SYSTEMS

PROGRAM APPLICABILITY: 2515 (SUPPLEMENTAL), 2525

61705-01 INSPECTION OBJECTIVES

01.01 For boiling water reactor (BWR) plants, to determine

that:

a. the local power range monitor (LPRM) system has been properly

calibrated to the local neutron flux.

b. the average power range monitor (APRM) system has been

properly calibrated to the core thermal power.

01.02 For pressurized water reactor (PWR) plants, to determine

that:

a. the source, intermediate, and power range detector calibrations have been properly performed and at the required

frequency.

b. the incore/excore detector calibration has been properly

performed and at the required frequency.

61705-02 INSPECTION REQUIREMENTS

02.01 LPRM Calibration. Select a recent LPRM calibration

procedure and calibration data to verify the following:

a. Records of the LPRM calibration are retained.

b. The procedure used to calibrate LPRMs is technically adequate

and contains:

1. a requirement for the performance of a full-core flux map

using the Traversing Incore Probe (TIP) system before

LPRM amplifier gain adjustment

2. a requirement for the operator to check for unacceptable

Base Crit Codes by running the P-1 computer program after

completion of the full core flux map
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3. appropriate precautions and prerequisites

c. Input calibration current was properly calculated for each

LPRM.
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d. Proper LPRM calibration adjustments were made by qualified

personnel, using an approved written procedure and the new

calibration current.

e. The APRM channel bypassed during its respective LRPM calibration was adjusted to keep APRM signal magnitude constant.

f. The LPRM calibration constant "C" did not change significantly

from its previous value.

g. The LPRM calibration frequency meets the plant's technical

specification requirements.

h. The instruments and calibration equipment used were traceable

to the National Bureau of Standards.

i. Test equipments used and their serial numbers were recorded

on the procedure.

j. Licensee's procedures ensure that the setpoint levels for

alarms, permissive and prohibitive interlocks are in compliance with the appropriate technical specifications.

k. Calibration results were reviewed, approved, and documented

in accordance with the licensee's administrative control

procedures.

02.02 APRM Calibration. Review the results of a recent APRM

system calibration to verify the following:

a. All precautions and prerequisites were met.

b. Steady-state recirculation flow, power level, and xenon

concentration existed during the calibration.

c. Only one APRM channel per reactor protection system (RPS) bus

was bypassed at a time.

d. APRM channels were properly adjusted to read the calculated

percent rated power.

e. Frequency of calibration meets the plant's technical specification requirements.

f. The instruments and calibration equipment used were traceable

to the National Bureau of Standards.

g. Test equipments used and their serial numbers were recorded

on the procedures.

h. Licensee's procedures ensure that the setpoint levels for

alarms, permissive and prohibitive interlocks are in compliance with the appropriate technical specifications.

i. Calibration results were reviewed, approved, and documented

in accordance with the licensee's administrative control

procedures.
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02.03 Source, Intermediate, and Power Range Detector Calibrations. Review the results of source, intermediate, and power range

detector calibrations to verify the following:

a. All precautions and prerequisites were met.

b. Power supply voltages were all within tolerance.

c. Frequency of calibration meets the plant's technical specification requirements.

d. Source range plateau voltage was determined properly and the

correct voltage was used for subsequent calibration (source

range detectors only).

e. Discriminator voltage was determined properly and the correct

voltage was used for subsequent calibration (source range

detectors only).

f. Compensating voltage was determined properly for the intermediate range detectors (compensated ion chamber detectors

only).

g. High voltage setting was properly set for the intermediate and

power range detectors (compensated ion chamber detectors

only).

h. 100% current value was correctly calculated for the power

range detectors.

i. The instruments and calibration equipment used were traceable

to the National Bureau of Standards.

j. Test equipments used and their serial numbers were recorded

on the procedure.

k. Licensee's procedures ensure that the setpoint levels for

alarms, permissive and prohibitive interlocks are in compliance with the appropriate technical specifications.

l. Calibration results were reviewed, approved, and documented

in accordance with the licensee's administrative control

procedures.

02.04 Incore/Excore Calibration. Review the results of a recent

incore/excore calibration to verify the following:

a. The test procedure includes:

1. adequate prerequisites and initial conditions

2. step-by-step instructions to induce xenon oscillation and

to stop the oscillation, if necessary (Westinghouse (W)

only)
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3. applicable limiting conditions for operation (LCO) and

other limitations specified in the plant technical

specifications

4. step-by-step recovery procedure, if abnormal xenon

transient occurs during the test ( W only)

b. Axial flux difference required by the plant technical

specifications was not exceeded during the test.

c. Control rod insertion limit was not exceeded during the

calibration.

d. For the condition, 0% incore axial flux difference, and at

calibration reference power, normalized power range detector

current was correctly calculated ( W only).

e. Good linearity was exhibited by the graph of excore detector

current vs. incore axial flux difference ( W only).

f. All points plotted on the graph of "out-of-core offset" vs.

"full incore offset" and "backup incore offset" vs. "full

incore offset" were in the acceptable region (Babcock and

Wilcox (B&W) only).

g. Least square fit of points plotted on the "out-of-core offset"

vs. "full incore offset" yielded a line with a slope of

greater than or equal to 1.15 (B&W only).

h. The instruments and calibration equipment used were traceable

to the National Bureau of Standards.

i. All data collected were reasonable and calculations performed

were correct.

j. The value for the internal axial shape index (ASI) was within

required tolerance of the calculated ASI (Combustion Engineering (CE) only).

k. Calibration results were reviewed, approved, and documented

in accordance with the licensee's administrative control

procedures.

l. Incore/excore detector calibration frequency meets the plant's

technical specification requirements.

61705-03 INSPECTION GUIDANCE

General Guidance

a. BWR General Guidance. The LPRM system must be calibrated

periodically throughout the fuel cycle to compensate for the

depletion of the LPRM chamber. The calibration procedure

involves the use of the TIPs to measure the axial neutron flux

profile for comparison with the LPRM readings and the computer

for data storage and calibration. The TIPs must by
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intercalibrated because there is more than one TIP used to

calibrate the core and because outputs from different TIPs may

not necessarily be the same. The intercalibration procedure

runs the individual TIPs through a common channel to make

their output read the same.

The BWR plant process computer has many programs and

subroutines that may be used by the operator for a variety of

purposes. One of these programs is called OD-1, "Whole-Core

LPRM Calibration." The OD-1 program is called up in the

process computer to calibrate the LPRMs. After successfully

running the OD-1 program, the operator initiates the P-1

program. The P-1 program (Periodic Core Evaluation) is used

to obtain useful core thermal performance data for evaluation

by the operator and is normally run after the OD-1 program.

In addition, OD-1/P-1 combination is usually run a second time

to confirm the validity of the first printout and also to

ensure data has been properly stored in the process computer.

LPRMs should be recalibrated whenever there is an abrupt

change in the neutron flux. Therefore, the LPRM system is

recalibrated (1) during the initial startup, at each

particular power level used for test purposes; (2) following

a major control rod pattern change; (3) following a change to

a significantly different operating mode, such as derating;

and (4) after a refueling.

b. PWR General Guidance. The majority of (PWR) plants use

similar types of nuclear instrumentation. Source range

detectors are proportional detectors, intermediate range

detectors are either compensated ion chamber type or fission

detectors, and the power range detectors are uncompensated ion

chamber detectors. Some plants have combined the source range

proportional detectors and the intermediate range fission

detectors and call them wide range nuclear instrumentation

(WRNI). The basic principles involved in calibration of these

nuclear instruments remain the same.

Section 02.03 of this procedure is intended to cover the

majority of the nuclear instrumentation currently in use. The

inspector should use the applicable steps for his plant.

Likewise, Section 02.04 covers the calibration of excore

detectors for PWRs using incore detectors as a reference.

Because excore detectors are used for reactor protection,

plants need to ensure that linearity exists between incore and

excore detectors. W, B&W, and CE all perform their

incore/excore detector calibration slightly differently.

However, all three different methods are intended to verify

incore-to-excore detector linearity.

For