Regulatory Guide 1.133
| ML003740137 | |
| Person / Time | |
|---|---|
| Issue date: | 05/31/1981 |
| From: | Office of Nuclear Regulatory Research |
| To: | |
| References | |
| RG-1.133, Revision 1 | |
| Download: ML003740137 (7) | |
RMvaon 1 M 1 I1 U.S. NUCLEAR REGULATORY COMMISSION
REGULATORY GUIDE
OFFICE OF NUCLEAR REGULATORY RESEARCH
REGULATORY GUIDE 1.133 LOOSE-PART DETECTION PROGRAM 1 FOR THE PRIMARY
SYSTEM OF LIGHT-WATER-COOLED REACTORS
A. INTRODUCTION
posed technical specifications relating to reporting neces sary to ensure operation of the facility in a safe manner.
Criterion 1, "Quality Standards and Records," of Appen dix A, "General Design Critiera for Nuclear Power Plants," Paragraph 20.1(c) of 10 CFR Part 20, "Standards for to 10 CFR Part 50, "Domestic Licensing of Production and Protection Against Radiation," states that, in addition to Utilization Facilities," requires that structures, systems, and complying with the requirements therein licensees should components important to safety be designed, fabricated, make every reasonable effort to maintain exposures to erected, and tested to quality standards commensurate with radiation as far below the limits specified in Part 20 as is the importance of the safety functions to be performed and reasonably achievable.
that a quality assurance program be established and imple mented in order to provide adequate assurance that these This guide describes a method acceptable to the NRC
structures, systems, and components will satisfactorily staff for implementing the above regulatory requirements perform their safety functions. with respect to detecting a potentially safety-related loon part in light-water-cooled reactors during normal operation.
Criterion 13, "Instrumentation and Control," requires, This guide also outlines a program that can help licensees to in part, that instrumentation be provided to monitor meet the Part 20 criterion that exposures of station personnel variables and systems over their anticipated ranges for to radiation during routine operation of the station will normal operation, for anticipated operational occurrences, be "as low as is reasonably achievable" (ALARA).
and for accident conditions to ensure adequate safety,
"-* including those variables and systems that can affect the The Advisory Committee on Reactor Safeguards has.
fision process, the integrity of the core, and the reactor been consulted concerning this guide and has concurred inj coolant pressure boundary. the regulatory position.
Section 50.36, "Technic Specifications," of 10 CFR
B. DISCUSSION
Part 50 requires an applicant. )r a facility operating license to provide proposed technical specifications. Paragraph (cX2), The presence of a loose (i.e., disengaged and drifting)
"Limiting Conditions for Operation," identifies a proposed part in the primary coolant system can be indicative of technical specification relating to the lowest functional degraded reactor safety resulting from failure or weakening capability or performance levels of equipment required for of a safety-related component. A loose part, whether it be safe operation of the facility. Paragraph (cX3), "Surveillance from a failed or weakened component or from an item Requirements," identifies a proposed technical specifica inadvertently left in the primary system during construction, tion relating to test, calibration, or inspection to ensure refueling, or maintenance procedures, can contribute to that the necessary quality of systems and components is component damage and material wear by frequent impacting maintained, that facility operation will be within the safety with other parts in the system. A loose part can pose a limits, and that the limiting conditions of operation will be serious threat of partial flow blockage with attendant met. Paragraph (cX5), "AdministratiVrControls," requires departure from nucleate boiling (DNB) which in turn could an applicant for a fa.ility operating license to provide pro result in failure of fuel cladding. In addition, a loose part increases the potential for control-rod jamming and for lIn this guide the phrase loose-part detection program encom accumulation of increased levels of radioactive crud in the psses recommendations for system hardware and propammatic and primary system.
reporting procedures. Loose-part detection system refers only to system hardware. Lines indicate substantive changes from September 1977 issue.
USNRC REGULATORY GUIDES Comments should be sent to the Secretary of the Commission, U.S. Nuclear Regulatory Commission, Washington, D.C. 20555, Regulatory public Guidesacceptable methods are Issued to to describe the NRC andstaff makeofavailable to the Implementing Attention: Docketing and Service Branch.
specific parts of the Commission's regulations, to delineate tech- The guides are issued In the following ten broad divisions:
naques used by the staff in evaluating specific problems or postu lated accidents, or to provide guidance to appicknts. Regulatory 1. Power Reactors 6. Products Guides are not substitutes for regulations, and compliance with 2. Research and Test Reactors 7. Transportation them is not required. Methods and solutions different from those set 3. Fuels and Materials Facilities 8. Occupational Health out In the guides will be acceptable if they provide a basis for the 4. Environmental and Siting 9. Antitrust and Financial Review findings requiste to the issuance or continuance of a permit or 5. Materials and Plant Protection 10. General Copies of issued guides may be purchased at the current Government This guide was issued after consideration of comments received from Printing Office price. A subscription service for future guides In spa the public. Comments and suggestions for Improvements in these cific divisions is available through the Government Printing Office.
guides are encouraged at all times, and guides will be revised, as Information on the subscription service and current GPO prices may appropriate, to accommodate comments and to reflect new informa- be obtained by writing the U.S. Nuclear Regulatory Commission.
Ion or experience. Washington, D.C. 20555, Attention: Publications Sales Manager.
detection system senses that a predesignated alert level has T1. ptinkary purpose of the loose-part detection program been reached or exceeded. An alarm alerts control room is the early detection of loose metallic parts in the primary personnel when the alert level is reached or exceeded. 'In system. Early detection can provfde the time required to developing an automatic procedure for the continuous, avoid or mitigate safety-related damage to or malfunctions online detection of loose parts, some sensitivity will be of primary system components.
sacrificed to minimize the potential for false alert signals.
The manual data acquisition mode provides periodic moni The loose-part detection program also serves a second toring to detect loose parts, determine system operability purpose since it can minimize radiation exposure to station (including calibration), establish the alert level, and alert personnel by providing for the early detection and general the licensee to data that require evaluation but are of location of abnormal structural conditions. Information insufficient magnitude or incorrect character to otherwise from the program can be used by station personnel to focus initiate automatic alert procedures. Manual monitoring of their efforts when taking remedial action to minimize the the audio portion of the sensor signals provides very high formation -of wear-generated radioactive crud and to sensitivity to loose-part impacts with good capability for minimize the need for extensive structural repairs. The pecognizing spurious audio signals. Manual monitoring does, second purpose is consistent with the guidance contained in however, have the potential for increasing the burden on Regulatory Guide 8.8, "Informationi Relevant to Ensuring station personnel and should be used only on a periodic That Occupational Radiation Exposures at Nuclear Power basis.
Stations Will Be As Low As Is Reasonably Achievable,"
which provides guidance to licensees for maintaining The loose-part detection program outlined herein is not, occupational doses to individuals as far below the permissible intended to be a research program. Instrumentation and:,
limits specified in the NRC regulations as is reasonably procedures that will result in the need for disproportionate, achievable while, at the same time, providing guidance on amount of ittention by control room personnel are not I
methods to ensure that the sum of the doses received encouraged. Instrumentation that can be used to determine I
by all exposed personnel is also at the lowest practical level. the approximate size and location of a loose part but that does not interfere with the normal alert and false signal The Advisory Committee on Reactor Safeguards (ACRS) rejection function of the detection program would be and the NRC staff have, for the past several years, been useful in complementing other instrumentation to determine encouraging applicants to employ online loose-part detection the safety significance of a detected loose part. Loose parts systems in an attempt to stimulate technological development traveling through the primary system will generally accumu in that area. This approach has resulted in a substantial late, at least for a time, in such natural collection areas as increase in industry-wide experience and confidence in the plenumi in reactor vessels and steam generators. Therefore, 1-1 these systems and has resulted in the commercial production the NRC staff recommends that sensors be located at theie of loose-part detection systems by several engineering and and other natural collection areas. No benefit is seen in manufacturing organizations. All applicants for a construc instiumenting straight lines of pipe or other areas through tion permit or an operating license are required to describe which a loose part will quickly pass. Close scrutiny of a the loose-part detection program for the proposed reactor relatively small amount of clearly relevant data is consid (Section 4.4.6, "Instrumentation Requirements," of Regula ered a better detection program than cursory review of a tory Guide 1.70, "Standard Format and Content of Safety large volume of less significant data.
Analysis Reports for Nuclear Power Plants").
A prime consideration in developing the loose-part An improperly developed and poorly implemented detection program is the avoidance of procedures requiring loose-part program may require excessive attention by plant excessive attention by control room personnel and excessive operating personnel and more frequent inspections of the reporting by the licensee. The recommended program primary system that can result in increased radiation would require operator action or engineering review when exposure. For this reason, this guide emphasizes the need the detection methods indicate the presence or possibility for providing system features that will minimize false alert of a loose part or when performing periodic audio monitor signals and for developing diagnostic procedures that can be ing or when confirming the operability of the instrumenta quickly implemented to supplement information from the tion system. Licensee reports to the Commission during loode-part detection system to determine the short- and operation are necessary when defining the alert level, long-term safety significance of a loose part. A well-developed when a loose part is confirmed to be present, or when the loose-part detection system should enable discrimination of associated technical specification is violated.
the signal induced by the impact of a loose part from those signals induced by normal hydraulic, mechanical, and Although current loose-part detection systems can, in a electrical background noise and large amplitude electrical large number of cases, detect and indicate the approximate transients. location and weight of a loose part, other information (e.g.,
that obtained from plant process signals, from an inspection The loose-part detection program outlined in this of the facility, or from prior operating history) will be regulatory guide includes both automatic and manual necessary in most instances to determine the safety sign-if modes of data acquisition. These data acquisition modes icance of the loose part. Therefore, no action with respect automatic and manual detection of loose parts.
I provide for to reactor operation is recommended based on the informa The automatic data acquisition mode provides for oontinuous tion *btained from the loose-part detection system alone.
monitoring of signals, but data are recorded only when the
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An alert resulting from the loose-part detection system is reactors during preoperational testing and the startup and considered a warning, and it is important that followup power operation modes in accordance with the following steps (e.g., acquisition of additional diagnostic information) guidelines:
be taken to determine the significance of the alert signal.
If a loose part is shown to be present, its short- and long-term 1. System Characteristics safety implications need to be determined.
The following fe atures should be incorporated into each The potential for damage initiated by a loose part is not loose-part detection system.
necessarily proportional to the impact energy of the loose part. For example, a small piece of flat metal plate may a. Sensor Location. Sensors capable of detecting acoustic impart little impact energy but could restrict local flow to disturbances should be strategically located on the exterior the reactor core. However, there are technical difficulties in surface of the reactor coolant pressure boundary. A mkimum trying to distinguish very-low-energy impact signals from of two sensors, suitably located to provide broad coverage, the normal reactor acoustic background noise. Experience should be located at each natural collection region (e~g.,
with loose-part detection systems for operating pressurized reactor vessel upper and lower plenums and each pressurized and boiling water reactors provides the basis for establishing water-reactor steam generator reactor wolant inlet plenum).
an impact energy of 0.5 ft-lb (0.68 joules), e.g., the kinetic energy of a 0.5-lb (0.23 kg) part traveling at 8 ft/sec (2.4 m/ b. System Senitivitly. The online sensitivity of the sec), as the recommended system sensitivity in Regulatory automatic detection system should be such that, as a Position 1.b. Experience shows that signals resulting from minimum, the system can detect, metallic loose part that metallic-object impacts of that magnitude are distinguishable weighs from 0,25lb (0.11 kg) to 301b (13.6kg) and from the normal background noise, and that, in some impacts with a kinetic energy of 0.5 ft-lb (0.68 joules)
instances, even smaller impact energies are discernible at on the inside surface of the reactor coolant pressure bound signal levels within background noise levels when the ary within 3 feet (0.91 meter) of a sensor. If the recom manual audio monitoring mode is being used. mended sensitivity cannot be achieved by automatic alert because of specific in-plant conditions, these conditions and In order to ensure that, as a minimum, each loose-part the actual online sensitivity should be specified at the time detection system has the ability to detect what the staff the alert level is provided (see Regulatory Position 3.a(2Xa)).
considers to be the most significant range of loose-part As an example, one acceptable method for verifying this weights, the staff recommends (Regulatory Position 1.b) online sensitivity is to demonstrate (1) the basic system that each loose-part detection system be capable of auto sensitivity during plant shutdown and (2) that the background matically detecting loose parts that weigh between 0.25 lb noise measured during normal plant operation is sufficiently
(0.11 kg) and 30 lb (13.6 kg) and impact with an energy of small that the signal associated with the specified detectable
0.5 ft-lb (0.68 joules) or more. The specified weight range is loose-part impact would be clearly discernible in the considered to be representative of the most common and presence of this background noise.
significant class of loose parts. In addition, the staff recom mends periodic audio monitoring by station personnel to c. Channel Separation. The instrumentation channels complement the automatic detection system. (e.g., cabling, amplifiers) associated with the two sensors recommended at each natural collection region should be The high radiation and thermal cycling environment to physically separated from each other starting at the sensor which most of the primary system is subjected could in locations to a point in the plant that is always accessible time alter operating characteristics of the loose-part detec for maintenance during full-power operation.
tion system so that surveillance becomes ineffectual either by causing excessive alert signals or by decreasing sensitivity d. DataAcquirition System. The system should include to loose parts. Therefore, in Regulatory Position 1f the staff both automatic and manual startup of data acquisition recommends that provisions be incorporated into the system equipment (see Regulatory Position 3). In the event the to permit channel operability (including calibration) tests. alert level is reached or exceeded, the data acquisition Regulatory Position 5 addresses operability tests as part of a system should automatically activate, and an audible or surveillance requirement for aproposed technical specification. visual alarm should alert the control room personnel of that condition. The data acquisition system should provide for Since an earthquake could induce a loose part in the the recording of all sensor signal waveforms in either analog primary system, it is desirable that the loose-part detection or digital form with the acceptability for selecting, as a system be designed to function following all seismic events minimum, any four sensors for simultaneous recording.
that do not require plant shutdown. Recording equipment, The system should be capable of immediate visual and however, need not be designed to function without main audio monitoring of all signals.
tenance following such seismic events provided the system retains audio or visual alarm capability. e. Alert Level. Provision should be made for incorporat ing into the system an alert level that is indicative of the
C. REGULATORY POSITION
presence of a loose part consistent with Regulatory Position
1.b. Depending on the alert logic (i.e., internal processing of An inservice loose-part detection program should be system signals), raw or processed signals should be auto implemented for the primary system of light-water-cooled matically and continuously compared to the alert level.
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Points to be considered In establishing the alert level are The following points should be considered when estab noted in Regulatory Position 2..
lishing the alert levels:
f. Capabilityfor Senior Channel Operabi#ty Test:. Pro vision should be made for periodic online channel check a. The alert logic should incorporate suitable internal and channel functional tests and for offline channel calibra criteria to distinguish the transient signal caused by the impact of a loose part from the signals associated with tion2 during periods of cold shutdown or refueling (see normal hydraulic, mechanical, and electric noise and Regulatory Position 3.a(3)). large-amplitude electrical transients. For example, it may be desirable to include logic that requires the comparison of g. Operabltyfor Seismic and Envwmnmental Conditions.
two or more sensor signals with the alert level.
Components of the loose-part detection system within containment should be designed and installed to perform b. False alert signals resulting from plant maneuvers their function following all seismic events that do not (e.g., c0ntrol-rod stepping, reactor trip, pump starts, and require plant shutdown, i.e., up to and including the Operat other known sources that cannot be avoided by the pro ing Basis Earthquake (ODE). Recording equipment need cedures associated with Regulatory Position 2.a) may be not function without maintenance folloiing the specified avoided by automatic procedures that momentarily override seismic event provided the audio or visual alarm capability the alert-level alarm. Alternatively, administrative proce remains functional. The system should also be shown to be dures may be used by control room personnel in lieu of adequate by analysis, test, or combined analysis and test for automatic procedures to identify and make allowance for the normal operating radiation, vibration, temperature, and alert signals caused by plant maneuvers.
humidity environment.
c. The alert logic maj provide for the alert level to be a h. Quality of System Components. Components should function of the normal steady-state operating condition.
be of a quality that is consistent with minimum maintenance requirements and low-failure rates. Components within the d. As appropriate, it may be desirable for the alert logic containment should be compatible with the 40-year design to provide for the alert level to vary from sensor to sensor life of the reactor system. In those instances where a to compensate for the inherent level of background noise at
40-year design life is not practicable, a replacement program a specific transducer location.
should be established for these parts that are anticipated to have limited service life. 3. Using the Data Acquisition Modes i. System Repair. The system should be designed to The loose-part detection program should include data facilitate the recognition, location, replacement, repair, and acquisition in automatic and manual modes. The automatic adjustment of malfunctioning components. Equipment, mode is for continuous, online detection of loose parts. The procedures, and layout should facilitate maintenance manual mode Is to be used periodically for detecting loose to minimize personnel time in high radiation areas and parts, determining systqm operability (including calibration),
minimize occupational radiation exposure. establishing the alert level, and detecting significant safety related trends in the sensor signals and for diagnostic
2. EstablidshIng the Alert Level purposes.
In all cases, the alert level should be consistent _with a. Manual mode. This mode of data acquisition should Rejulatory Positions l.b and I.e and should include the be used at the following times for the indicated purpose.
effects of background noise.
(1) Preoperational testing: Establish alert level for this test phase.
2 The standard technical specificatlons define channel (2) Startup and power operation.
cannel funcional Wt, and chamnel calibmaton as follows. check, A chlannl check Is the qualitative messment of channel behavior (a) Establish alert levels for startup and power during operation by observation, Including, where possible corn operation. The alert level for power operation should be parbon of the channel indication or status with other Indications or status derived from independent instrument channels measuring the submitted to the Commission (in the startup report when same parameter. one Is provided) within 90 days following completion of A channel funcfoN*l test -for analog channels is the injection of a the startup test program If the alert level is for power simulated signal into the channel as close to the primary sensor a
.racticable to veaty oper bility, including alarm and trip functions; operation following initial startup or there is a change to or b.staboe channels it is the injection of a simulated signal the channel sensor to vefy operability, including alarm and into trip the preexisting alert level for power operatio
n. Temporary I
functions. changes to the alert level need not be reported.
A channel calbrafion is the adjustment, as necessary, of the channel output so that it responds with the necessary range and accuracy to (b) At least once per 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />s: Perform channel I
known values of the parameter that the channel chmel calibration encompasses the entire channel, monitors. The including the check.
sensor and alarm and trip functions, and includes the channel functional test. The channel calibration may be performed by any serie of sequential overlapping, or total channel steps so that the (c) At least once per 7 days: Listen to audio entire channel incalbrated. 1-1 portion of signals from all recommended sensors foro the
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a. Sensor types, mounting locations, and mounting indicate the presence or possibility of a loose part, station procedures, including criteria for choice of sensor and nnel should actuate the data acquisition system to mounting locations.
9purpose of for sin data detecting furtherthe presence of loose parts. If signals evaluation.
b. Data acquisition, recording, and calibration equipment.
(d) At least once per 31 days: Perform channel functional tests. c. Anticipated major sources of external and interiel extraneous noise.
(e) At least once per 92 days: Verify that the background noise measured during normal plant operation is d. Precautions taken to ensure acquisition of quaUty sufficiently small that the signal associated with the specified data.
detectable loon-part impact would be clearly discernible ip the presence of this background noise. Verify that the signal e. Description of the manner in which the alert level will from each recommended sensor does not falsely indicate be determined and also the alert logic (if any) employed by the presence of a loose part. This should include comparison with data, including audio data, obtained at the time of the the system hardware and software in gnerating an alert last two quarterly measurements to verify that there does signal. This should include a description of the Program not exist a significant trend or anomaly that may falsely capability for distinguishing between a loose part and normal background noise.
indicate the presence of a loose part. The alert level and alert logic may be revised to provide for the background noise of f. Reference to the technical specification (see Rgula these later measurements. If the revision is not temporary, tory Position 5).
its details should be submitted within 60 days to the Com mission as an amendment to the program description.
g. Summary of supplemental data and diagnostic procedures that are available and that can be used as part of
(3) Cold shutdown or refuellng: At least once per a diagnostic program to confirm the presence of a loom
18 months, verify channel calibration using a controlled part. The summary should address the use of Information mechanical input (e.g., weight falling through a known distance that impacts the external surface of the reactor from plant process; signals, radiation lakap monitors, operating history, exercising of control rods, cycling of coolant pressure boundary). Channels should, as necessary, primary coolant pumps, and inspection of the. primary be recalibrated at this time. If recalibration Is necessary, coolant system.
...,.onsideration should be given to replacement of unstable mponents. h. Procedures for performing channel check, channel functional test, and background noise measurements.
b. Automatic mode. The automatic mode should S-- be activated automatically when the predesignated alert level is I
exceeded. Activation should comprise an audible or visual I. Procedures for minimizing radiation exposure to station personnel during maintenance, calibration, and alarm to the control room operator and simultaneous initia diagnostic procedures. (Reference in Chapter 12, "Radiation tion of data recording equipment. Data should be acquired Protection," of the Safety Analysis Report.)
for a sufficient period of time to properly characterize the signals from sensors suitably selected to provide maximum J. Training program for plant personnel that addreses diagnostic information (e.g., the alarming sensor and several operation of the system hardware and the purpose and adjacent sensors may be selected). Each alert should be implementation of the loose-part detection prsoram.
documented with regard to time and plant condition. (Reference in Chapter 13, "Conduct of Operations," of the Safety Analysis Report.)
If the alert level is exceeded or if the weekly audio monitoring or quarterly measurements indicate the presence or possibility of a loose part, diagnostic steps should be k. The applicant should verify that the system within containment will be designed and installed to functionI
taken within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to determine whether a loose part is following. all seismic events up to and including the ODE.
present and to determine its safety significance.
5. Technical Specification br die Loos&Part Detectimo System
4. Content of Safety Analysis Reports A technical specification for the loose-part detection A description of the loose-part detection program should be submitted to the Commission in response to the NRC system should be provided.- The technical specification should include:
staff request for information on loose-part detection systems in Section 4.4.6, "Instrumentation Requirements," of Regu latory Guide 1.70, "Standard Format and Content of Safety Analysis Reports for Nuclear Power Plants."
a. The location of the required sensors.
I
b. A limiting condition for operation requiring the The program description should include those items loose-part detection system to be operable during startup
-covered in Regulatory Positions 1,2, and 3. Special attention and power operation. If all channels of one or more collec tion regions are inoperable for more than 30 days, the S-should be given to the following items: reactor need not be shutdown, but a special report should
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be prepared and submitted to the Commission within the next 10 days outlining the cause of the' malfunction with the specified portions of the Commission's regulations, I
the method described herein will be used by the NRC staff and the plans for restoring the channel(s) to an operable in the evaluation of all construction permit applications and status. all operating license applications under review by the staff after January 1, 1978.
c. A surveillance requirement that each channel of the loose-part detection system be demonstrated operable by a channel check performed at least once per 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, For reactors licensed to operate prior to January 1, 1978, a channel functional test performed at least once per loose-part detection systems that conform to commitments
31 days, and a calibration test performed at least once per of the license application should be installed and operable.
18 months. The installation should be reviewed by the licensee to ensure that the quality of the installation and the calibra-.
6. Notification of a Loose Part tion and use of the equipment are consistent with the recom mendations of this guide to the extent feasible for the loose If the presence of a loose part is confirmed, the Commis part detection system to which the licensee committed. The sion should be notified according to the guidelines for review should include an evaluation of the conformance to reportable occurrences that call for "prompt notification the appropriate programmatic aspects of the guide, specifi with written followup" as summarized in Regulatory cally Sections C.2 and C.3, and whether specific hardware Guide 1.16, "Reporting of Operating Information-Appendix or installation modifications are needed to make the systems A Technical Specifications." effective for the detection of loose parts.
The followup report to be submitted to the Commission within 2 weeks of the initial notification of the presence of In cases where licensees of operating reactors (licensed a loose part should include (1) a summary of data obtained prior to January 1, 1978) have not previously committed to in the manual and automatic data acquisition modes; (2) a install a loose-part detection system or where the design of summary of the analysis, inspections, and correlations with an existing system precludes upgrading to an effective operating data that were performed to evaluate data from functional capability, the licensee should install a system in the loose-part detection program; and (3) a summary of conformance with the programmatic aspects of the guide, conclusions and a description of modifications or other specifically Sections C.2 and C.3, or propose an acceptable actions planned or already performed to evaluate the safety alternative. In cases where a loose part is known to be implication of the loose part or to ensure that system and present or there exists a high probability that a part may component safety functions are not impaired. become loose based on experience with other reactors of similar design, a loose-part detection system conforming td
D. IMPLEMENTATION
this guide should be installed.
The purpose of this section is to provide information to A letter will be sent to the licensee for each operating applicants regarding the NRC staff's plans for using this plant requesting that each licensee complete a review of his regulatory guide. loose-part detection program and make any appropriate provisions for equipment and program revisions. Documenta This guide reflects current NRC staff practice as outlined tion describing the results of this review and the resultant in Section 4.4 of the Standard Review Plan. The method loose-parts detection program should be prepared and presented in this guide has been recognized as acceptable available for inspection. It is the intent of the NRC to for complying with the Commission's regulations since require that this effort, including the documentation, be January 1, 1978. completed within 6 months after the effective issuance date of this guide unless additional time is justified by the Therefore, except in thQse cases in which the applicant licensee in response to the NRC request to review the proposes an acceptable alternative method for complying loose-part detection program.
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UNITED STATES
NUCLEAR REGULATORY COMMISSION
WASHINGTON, D. C. 20555