ML20114B939
| ML20114B939 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 08/24/1992 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20114B937 | List: |
| References | |
| NUDOCS 9208310367 | |
| Download: ML20114B939 (4) | |
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WASHINGTON. D.C. 20556 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION REL ATED TO AMENDMENT NO.172 TO FAClllTY OPERATING LICENSE NO. NPF-3 TOLEDO EDISON COMPANY CENTER 10R SERVICE COMPANY A"l I
THE CLEVELAND ELECTRit ILLUMINATING COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT NO. I DOCKET NO. 50-346 d
1.0 INTRODUCTION
By letter dated February 2,1990, the ~;ledo Edison Company (the licensee) requested changes to Technical Specification (TS) 3/4.3.6, Post Accident Monitoring Instrumentation, which would add neutron flux (wide range) and neutron flux (source rangej innt,'umentation to Tables 3.3-10 and 4.3-10 *n reflect the appropriate surveillance requirements for the new monitors.
% jd3 tion this proposed amendment would revise TS 3/4.9.2, Refueling Operati;
- lustru-s mentation, by adding a requirement to calibrate the neutron flux
- nitors prior to entry into Mode 6.
The licensee has been using the excore neutron flux monitors supplied with the Bat ock & Wilcox (B&W) nuclear instrumentation system to meet both TS 3/4.9.2 and 3/4.3.1.1, Reactor Protection System Instrumentation, Table 3.3-1 and 4.3-1, Item 11 (Source Range, Neutron Flux and Rate - Startap and Shutdown).
However, the B&W-supplied nuclear instrumentation system is not environmentally qualified.
Two excore neutron flux monitors (each with wide range and source range capa-bility) qualified to meet the requirements of Regulatory Guide 1.97, "Instru-mentation for Light-Water-Cooled Nuclear Power Plants to Assess Plant and Environs Conditions During and Following an Accident," were. installed during the fifth refueling outage.
2.0 EVALUATION The nuclear instrumentation (NI) system is designed to provide neutron flux information over the full range of reactor operations.
To provide total monitoring, three ranges of neutron flux detectors are furnished: source range, intermediate range and power range. The NI system consists of two source range channels, two intermediate range channels and four power range channels.
This arrangement allows continuous monitoring of neutron flux level from source range 9208310367 9pogg4 DR p
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to 125% of rated power.
A minimum of one decade overlap between ranges is provided.
The power range detectors are required by the reactor protection system (RPS) to perform safety functions, and are part of the RPS.
During refueling (Mode 6), the operability of the source range neutron flux monitors ensures th;.t redundant monitoring capability is available to detect l
reactivity changes in the core.
The purpose of the post-accident monitoring system (PAMS) is to follow the course of an accident condition with wide range instrumentation which provides the operators the essential safety status information needed to return the plant to a maintained, safe shutdown condition.
The operability of the post-accident monitoring system ensures that sofficient information is available on selected plant parameters to monitor and assess these variables following an accident.
Supplement I to NUREG-0737, " Clarification of THI Action Plant Requirements,"
2 directs the installation of various instrumentation systems as specified in Regulatory Guide 1.97, and specifies that neutron flux measurements must be made to indicate whether plant safety functions are being accomplished and to provide information required to mitigate the consequences of an accident.
Regul atory Guit 1.97 further specifies that the neutron flux measurements must De made with components /u.! re that meet certain criteria among which are that the equipment is environmentally qualified per Regulatory Guide 1.89, " Qualification of Clar IE Equipment for Nuclear Power Plants," and the methodology described in NURES 0588, " Interim Staff Position on Environmental Qualification nf Safety-Related Electrical Equipment."
Although the B&W-supplied NI system components do not meet the Regulatory Guide 1.97 criteria, Supplement I to NUREG-0737, paragraph 6.1.b, permits plants to rely on currently installed equipment even if it is presently not environmentally qualified.
The aquipment is required to eventually be replaced with environ-mentally qualified components. The new excore neutron flux monitoring system was installed to comply with Supplement I to NUREG-0737 and it meets the requirements tiiat are specified in Regulatory Guide 1.97.
The components are:
(a)
Environmental 5 qualified per IEEE 323-1974, " Standard for Qualifying Class IE Equipment for Nuclear Power Generating Stations,"
(b)
Seismically qualified per IEEE 344-1975, " Recommended Practices for Seismic Qualification of Class IE Equipment for Nuclear Power Generating Stations,"
(c)
Independently separated per IEEE 384-1977, " Standard Criteria for Independence of Class IE Equipment and Circuits," and (d)
System cables splices, and connections are qualified per IEEE 383-1974, "Standar'i for Type lest of Class IE Electric Cables, Field Splices, ano Connections for Nuclear Power Generating Stations" l
1
. The new Gamma-Metrics supplied excore neutron flux monitoring system provides i
neutron flux measurement frnm reactor shutdown to reactor full power level.
The new system consists of two independent channels each with a source range and wide range display.
Prior to the modification whict installed the new excore neutron flux munitoring system in addition to the or9pnal B&W-supplied nuclear instru-mentation system, the NI system alsa provida in the control room and containment daring refueling operations an audibie indication of the source range counts.
The two new excore monitors will be used to provide the audible indication of source range counts in the control room and containment during refueling operations.
The two new excore monitors will also be available to be used in addition to the orig-inal NI system to provide the visual indication of source range counts in the control room during refueling operations.
The new monitors should be included in the technical specifications and appropriate surveillance testing be reflected to demonstrate operability of the monitors.
Specifically, two new line items "36.
Neutron Flux (Wide Range)" and "37. Neutron Flux (Source Range)" are proposed to be added to Tables 3.3-10 and 4.3-10.
This will require a minimum of one channel of each to be operable in Mode 1 (Power Operation) through Mode 3 (Hot Standby),
that a channel check be performed monthly and a channel calibration be performed at each refueling.
These requirements are similar to those of other PAMS instru-ments.
The neutron detectors must be excluded from the channel calibration due to their non-adjustability (channel gain is adjustable).
Since, during refueling operations, the new monitors will provide the audible indication of source range counts in the control room and containment and will be available in addition to the B&W-supplied NI system to provide the visual indica-tion of source range counts in the control room, appropriate changes are required for TS 3/4.9.2.
In order to ensure that the neutron flux in the core is appro-priately monitored during refueling operations, the LCO has been modified to require that the two operable neutron monitors be from separate channels (and, therefore, from opposite sides of the core). A channel calibration (TS 4.9.2d) of the monitors will be required to be performed prior to entry into Mode 6 (Refueling), if not perforned within the last 18 months. The addition of this requirement is necessary because a channel calibration requirenent for the new monitors does not exist, while the original NI system u calibrated by TS 3/4.3.3.1 requirements on a refueling basis. As the proposed Surveillance Requirement will apply to both the original and new flux monitors, the phrases "if not performed within the last 18 months" must be included to provide necessary flexibility in scheduling the chanr.el calibration of the original monitors.
These monitors are typically calibrated during the latter stages of a refueling outage and not prior to Mode 6 entry.
It is intended that TS 4.0.2. (1.2S criterion) would also be applicable to the channel calibration frequency of 18 months.
It should be noted that the original NI system will continue to be utilized to meet its previous TS 3/4.3.1.1 requirements.
The proposed changes would not increase the probability of equipment degradation because there would be no decrease in TS operability and surveillance require-ments.
The B&W-supplied NI will continue all of its present functions and the new excore neutron flux monitoring system will provide an independent and qualified system with additional TS operability and surveillance requirements.
T"e proposed changes do not inhibit the function of existing Cla:' IE equipment and there is no
i
. The new Gamma-Metrics supplied excore neutron flux monitoring system provides neutron flux measurement from reactor shutdown to reactor full power level.
The new system consists of two independent channels each with a source range and wide range display.
Prior to the modification which installed the new excore neutron flux monitoring system in addition to the original B&W-supplied nuclear instru-mentation system, the NI system also provided in the control room and containment during refueling operations an audible indication of the source range counts.
The two new excore monitors will be used to provide the audible indication of source range counts in the control room and containment during refueling operations.
The two new excore monitors will also be available to be used in addition to the orig-inal NI system to provide the visual indication of source range counts in the control room during refueling operations.
The new monitors should be included in the technical specifications and appropriate surveillance testing be reflected to demonstrate operability of the monitors.
Specifically, two new line items "36.
Neutron Flux (Wide Range)" and "37. Neutron Flux (Source Range)" are proposed to j
be added to Tables 3.3-10 and 4.3-10.
This will require a minimum of one channel of each to be operable in Mode 1 (Power Operation) through Mode 3 (Hot Standby),
that a channel check be performed monthly and a channel calibration be performed at each refueling.
These requirements are similar to those of other PAMS instru-ments. The neutron detectors must be excluded from the channel calibration due to i
their non-adjustability (channel gain is adjustable).
Since, during refueling operations, the new monitors will provide the audible indication of source range counts in the-control room and containment and will be available in addition to the B&W-supplied NI system to provide the visual indica-i tion of source range counts in the control room, appropriate changes are required for TS 3/4.9.2.
In order to ensure that the neutron flux in the core is appro-priately monitored during refueling operations, the LCO has been modified to require that the two operable neutron monitors be from separate channels (and, therefore, from opposite sides of the core). A channel calibration (TS 4.9.2d) of the monitors will be required to be performed prior to entry into Mode 6 (Refueling), if not performed within the last 18 months.
The addition of this requirement is necessary because a channel calibration requirement for the new i
monitors does not exist, while the original NI system is calibrated by TS 3/4.3.3.1 requirements on a refueling basis.
As the proposed Surveillance Requirement will apply to both the original and new flux monitors, the phrases "it not performed within the last 18 months" must be included to provide necessary flexibility in scheduling the channel calibration of the original monitors.
These monitors are typically calibrated during the latter stages of a refueling outage and not prior to Mode 6 entry.
It is intended that TS 4.0.2. (1.25 critericn) l would also be applicable to the channel calibration frequency of 18 months.
It should be noted that the original NI system will continue to be utilized to meet its previous TS 3/4.3.1.1 requirements.
The proposed changes would not increase the probability of equipment degradation because there would be no decrease in TS operability and surveillance require-ments.
The BW-supplied NI will continue all of its present functions and the new l
excore neutron flux monitoring system will provide an independent and qualified i
system with additional TS operability and surveillance requireu nts.
The proposed changes do not inhibit the function of existing Class lE equipment and there is no l
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. I radiological consequence associated with the increased TS requirements.
The proposed changes will ensure that the new system is adequately tested at the apprcpriate frequency.
The staff has reviewed the proposed changes to TS 3/4.3.6 and 3/4.9.2 and finds saat the addition of a qualified excore neutron flux monitoring system is acceptable.
3.0 STATE CONSULTATION
In acccrdance with the Commission's regulations, the Ohio State official was notified of the proposed issuance of the amendment.
The State official had no comments.
4.0 ENVIRONMENTAL CONSIDERATION
This amendment changes a requirement with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 or changes a surveillance requirement.
The staff has determined that the amendment involves no significant ircrease in the amounts, and no.significant change in the types, of any effluents that may be released offsite, and titat there is no significant increase in individual _ or cumulative occupational radiation exposure, The Commission has previously issued a_ proposed finding that the amendment involves no significant hazards consideration and there has been no public comment on such finding (56 FR 43813).
Accordingly, the amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9). Pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendment.
5.0 CONCLUSION
The staff has concluded, based on the considerations discussed.above, that:
(1) there is reasonable assurance that _the health and safety of the public will-not be endangered by operation in the proposed manner, (2).such activities.will be conducted in_ compliance with the Commission's regulations, and (3)-the issuance of this amendment will nct be inimical to the common defense and security or to the health and safety of the-public.
Principal Contributor: James J. Lombardo Date: August 24, 1992 l
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