ML17146B163
| ML17146B163 | |
| Person / Time | |
|---|---|
| Site: | Susquehanna  |
| Issue date: | 07/30/1999 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML17146B162 | List: |
| References | |
| NUDOCS 9908040192 | |
| Download: ML17146B163 (11) | |
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UNITEf STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 SAFETY EVALUATIONBY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENTNO.
TO FACILITYOPERATING LICENSE NO. NPF-14 AMENDMENTNO. 158 TO FACILITYOPERATING LICENSE NO. NPF-22 PP&L INC.
ALLEGHENYELECTRIC COOPERATIVE INC.
SUS UEHANNASTEAM ELECTRIC STATION UNITS 1 AND 2 DOCKET NOS. 50-387 AND 388
1.0 INTRODUCTION
By letters dated June 19, 1998 (Unit 1), August 5, 1998 (Unit 2), November 23, 1998 (Units 1 and 2), and June 23, 1999, PP8L, Inc. (the licensee) proposed license amendments to change the Technical Specifications (TSs) for Susquehanna Steam Electric Station (SSES), Units 1 &
- 2. The proposed amendments incorporate long-term power stability solution instrumentation into the SSES Units 1 and 2, TSs. The changes reflect the addition of a new TS Section 3.3.1.3, "Oscillation Power Range Monitoring (OPRM) Instrumentation," and revisions to TS Section 3.4.1, "Recirculation Loops Operating," to remove specifications related to the current power stability specifications that will no longer be required.
The November 23, 1998, and June 23, 1999, letters provided clarifying information that did not change the initial proposed no significant hazards consideration determination or expand the scope of the amendment request.
The revised index pages for the Unit 2 TS issued with this amendment are renumbered to start at i instead of iii.
2.0 SYSTEM DESCRIPTION The digital-based OPRM described in ABB Combustion Engineering (ABB CE) topical report CENPD-400-P, "Generic Topical Report for the ABB Option III Oscillation Power Range Monitor (OPRM)," detects and suppresses reactor core power instabilities using the Option III approach described in NEDO-31960, "BWR Owners'roup Long-Term Stability Solutions Licensing Methodology," dated June 1991, and NEDO-31960, Supplement 1, dated March 1992, which were approved by the staff in safety evaluations dated July 12, 1993.
Using existing local power range monitors (LPRMs) and reactor core recirculation flow instrumentation, the OPRM provides independent oscillation detection algorithm (ODA) trip function outputs to the original reactor protection system (RPS) interface relays.
The OPRM consists of four independent channels, one per RPS channel.
Each OPRM channel consists of two modules, either of which can generate a channel trip signal. This configuration provides redundancy between OPRM channels and within each OPRM channel.
9908040i92 990730 PDR ADOCK 05000387 P
PDR Each OPRM module receives signals from dedicated LPRMs, and provides LPRM signals to the other module in its channel through a fiber optic data link. The OPRM module combines the locally wired LPRM signals with the shared LPRM signals to create LPRM cells that represent the neutron flux distribution in the reactor core.
A microprocessor in each module uses these cells of LPRM signals to calculate the trip function values with the ODAs described in NEDO-31960 and NEDO-31960, Supplement 1.
One OPRM module is installed in each LPRM page in the existing space in the LPRM amplifier card frame (An LPRM page is a collection of components in the power range monitoring cabinets which contains LPRM amplifier cards, wiring, and supporting electronics on a hinged assembly that allows access to the wiring and components behind the assembly).
Except for unassigned LPRM pages, there is one LPRM page per average power range monitor (APRM) set.
The OPRM module willbe connected to the APRM power and flow signals and the LPRM flux amplifier card outputs in its page.
In the Operate mode, the OPRM module performs the three diverse ODA calculations, runs self-tests, services the interpage data link, broadcasts channel information on the maintenance and plant computer data links, and provides annunciator indications to the main control room panel. The Trip output is automatically armed (Trip Enable) when the programmed high APRM power and low core flowsetpoints are reached.
The OPRM monitors the number of available and on-scale LPRMs and flags an LPRM cell as not valid if a sufficient number of LPRMs are not available or are not on-scale.
When Trip Enabled is armed, an alert to the operator of a Trouble condition results.
If no LPRM cells are valid, an inoperable (INOP) alarm is generated.
Trouble and INOP conditions caused by an insufficient number of LPRMs will not cause a reactor trip when at power. This design feature is acceptable because technical specification APRM limiting conditions for operation are intended to ensure that an APRM trip willoccur if a sufficient number of LPRMs are not available.
Additionally, regional core oscillations do not occur during low power operation when LPRMs are frequently out of range (and the corresponding LPRM cells are not valid). The OPRM Trip module relays and INOP module relays willchange state upon loss of power or when an OPRM module is physically removed from the chassis.
The OPRM protection system provides the following control board annunciator outputs to the SSES control room operator:
Trip Enable (the OPRM is armed)
Alarm (one or more cells calculating the period based algorithm have reached the pre-trip setpoint),
Trip (one or more cells have tripped),
INOP (the OPRM module may not be performing the ODA function),
TROUBLE (the OPRM module is performing the ODA function but requires operator attention).
A design option is available to the licensee to provide the operator with the above information through the plant process computer via a one-way data link. The above indications are also available at the OPRM module, where they remain latched until manually reset.
A keyswitch on each OPRM module panel provides the operator with administrative control of the OPRM operating modes.
The position of the keyswitch determines whether the OPRM module is in the Test or Operate mode.
The keyswitch in the Test position and entry of an OPRM access password are required to make configuration changes or perform surveillance tests.
While in the Operate mode, the OPRM module unidirectionally transmits LPRM and ODA status information to the maintenance terminal and plant computer fiber optic data links. This transmission occurs even when the maintenance terminal and plant computer are not connected or installed to the OPRM module panel.
A 20-minute event recall buffer in each OPRM module saves trip-related data for further analysis.
The event recall buffer data may be downloaded to the maintenance terminal or plant computer when the OPRM module is in the Test mode.
The OPRM module consists of a metal enclosure (which provides shielding against electromagnetic interference) with a removable circuit card assembly.
The metal enclosure is permanently mounted in the card file of the APRM or LPRM page.
Digital isolators and relays mounted remote from the OPRM provide isolation and fault protection for the OPRM digital inputs and outputs.
OPRM module repair is limited to module replacement.
The OPRM chassis connects to the LPRMs, the APRM power signal, the total flow signal, digital input signals, relays, power, and ground through a prefabricated pigtail connector.
OPRM modules are connected in pairs via fiber optic data links to ensure isolation between APRM/LPRM groups.
3.0 EVALUATION As stated in the staff's safety evaluation report (SER) that approved ABB CE topical report CENPD-400-P, "Generic Topical Report for the ABB Option III Oscillation Power Range Monitor (OPRM)," licensees referencing the topical report for implementation of the OPRM should provide the following information in their license amendment submittals:
1)
Confirm the applicability of CENPD-400-P, including clarifications and reconciled differences between the specific plant design and the topical report design descriptions.
2)
Confirm the applicability of Boiling Water Reactor Owners Group topical reports that address the OPRM and associated instability functions, set points and margins.
3)
Provide a plant-specific Technical Specification (TS) for the OPRM functions consistent with CENPD-400-P, Appendix A.
4)
Confirm that the plant-specific environmental (temperature, humidity, radiation, electromagnetic and seismic) conditions are enveloped by the OPRM equipment environmental qualification values.
5)
Confirm that administrative controls are provided for manually bypassing OPRM channels or protective functions, and for controlling access to the OPRM functions.
6)
Confirm that any changes to the plant operator's main control room panel have received human factors reviews per plant-specific procedures.
3.1 Applicabilityof the ABB Option III OPRM Design to the Plant Design The staff compared the applicable SSES design features with the corresponding design features in CENPD-400-P, Appendix A (CENPD-40G-P-A). The SSES units are General Electric/Boiling Water Reactor, GE BWR/4s; a BWR design addressed in CENPD-400-P-A.
The OPRMs are installed consistent with the system description provided in Section 2, above.
The only SSES deviation from the system description provided in Section 2 above, is that indications of Trouble conditions (the OPRM module is performing the ODA function but requires operator attention), are provided to the operators via the plant integrated computer system (PICSY), and are also indicated locally at the OPRM installed location. This optional display output was found acceptable in the SER approving CENPD-400-P-A. The staff, therefore, finds that the OPRM design is applicable to SSES.
3.2 Power Instability Functions, Set Points, and Margins The licensee tested the OPRM, including the adequacy of the setpoint values and margins during the first fuel cycle of OPRM operation.
At the end of the testing period, the licensee developed setpoints and margins that willbe incorporated into the limiting conditions for operation portion of the SSES TSs. These setpoints willbe consistent with the guidelines in NEDO-31 960 and NEDO-31960, Supplement 1.
3.3 Plant-Specific Revised TSs The following section describes the licensee's pioposed TS amendments and the NRC staff's evaluation of each proposed change.
3.3.1 Addition of TS 3.3.1.3, Oscillation Power Range Monitor (OPRM) Instrumentation, Limiting Condition for Operation (LCO) 3.3.1.3, Conditions, Required Actions, and Completion Times The licensee added the Period Based Algorithm setpoint and confirmation count permissive values to LCO 3.3.1.3.
The Conditions, Required Actions, and Completion Times of LCO 3.3.1.3 are consistent with CENPD-400-P-A.
3.3.2 Addition of TS 3.3.1.3, Oscillation Power Range Monitor (OPRM) Instrumentation, LCO 3.3.1.3, Surveillance Requirements (SRs)
In.SR 3.3.1.3.5, the licensee revised the minimum core flow requirement from 60% of rated recirculation drive flowto 60 MLb/Hr. The value used by the licensee is consistent with the existing TS limits, as defined in Figure 3.4.1-1, which have been used by the licensee in the existing interim corrective actions.
The staff, therefore, finds this deviation from CENPD-400-P-A to be acceptable.
The remainder of TS 3.3.1.3 SRs are consistent with CENPD-400-P-A.
3.3.3 Proposed Changes to TS Bases Section B.3.3.1.3, Oscillation Power Range Monitor (OPRM)
The TS 3.3.1.3 Bases are consistent with CENPD-400-P-A.
3.3.4 Changes made to Section 3.4 The changes made to Section 3.4 of the TSs are intended to reflect the fact that the Long Term Stability Option III allows operation without the need for restricted regions defined on the power-to-flow map. The restricted regions were intended to ensure that the plant did not have instability by avoiding operation in regions where instabilities were credible. The OPRM in Option III provides an automatic stability detection and suppression capability which provides better protection than the restricted regions.
Figure 3.4.1.1-1 defines the restricted regions currently in use at SSES.
Figure 3.4.4-1 and any references to it are, therefore, being deleted.
The remainder of the TS is unchanged including the requirement to immediately shutdown the plant if no recirculation pumps are operating.
Figure 3.4.1-1 is deleted.
This figure defined regions which were to be avoided to ensure that the plant did not exhibit unstable behavior.
These regions are no longer needed because the OPRM system automatically detects instabilities and willprovide at least the same level of protection as that provided by the Regions defined in Figure 3.4.1-1.
Reference to Figure 3.4.1-1 is removed from two locations in the statement of the LCO of TS 3.4.1. This change is acceptable because these references are no longer needed.
Reference to Region I on Figure 3.4.1-1 is removed from Action A of TS 3.4.1. This
~ reference required immediate reactor shutdown if the combined core thermal power/core flowfall within the area designated as "Region 1" on Figure 3.4.1-1.
This action is no longer required since the OPRM provides automatic protection against Region I instabilities.
Action B of TS 3.4.1 is deleted.
Action B was used to ensure that an oscillation could be properly detected and that, once detected, appropriate action was taken. These functions are now being performed by the automatic OPRM system included in Option III. Therefore, this action is no longer needed.
Action C of TS 3.4.1 is deleted.
Action C ensured that the plant was not operated in Region II of Figure 3.4.1-1. This action is no longer needed because the figure is being deleted.
SR 3.4.1.2 is deleted.
This SR ensured that the plant was operated outside of Regions I
and II on Figure 3.4.1-1
~ This SR is no longer needed.
3.4 Plant-Specific Environmental Conditions The licensee states that the OPRM components, including modules, digital isolator blocks, external relay boards, analog signal isolators, replacement power supplies and voltage regulators, and additional mounting hardware and separation barriers are accounted for in approved Seismic Qualification data file records.
The licensee reviewed the effect of the additional OPRM equipment on the seismic qualification of the Power Range Neutron Monitoring System Panel and approved the qualification in accordance with the requirements of the licensee's design control program.
These actions for seismic qualification are 'acceptable to the staff.
In Table 1 below, the SSES plant-specific environmental conditions at the OPRM installation location for temperature, humidity, pressure, and radiation are compared to the OPRM environmental qualification values.
As shown in Table 1, the generic OPRM qualification values envelope the SSES temperature and radiation environmental conditions and, therefore, are acceptable.
The generic OPRM qualification values for humidity do not envelope the SSES environmental conditions (low humidity limit). The licensee states that operation at humidity levels lower than 40% are justified because all OPRM circuit cards are coated with CONAP or an acrylic urethane, which isolates the electronic equipment from direct contact with a fow humidity environment and thereby addresses the primary concern of damage from electrostatic discharges, which can occur in low humidity conditions.
The staff finds this justification for the lower humidity limitto be consistent with guidance for protection against electrostatic discharge and, therefore, acceptable.
-Table 1. Comparison of SSES Environmental Conditions with OPRM Environmental Qualification Values Temperature Humidity Radiation SSES 15.6'C to 32.2'C (60'F to 90'F) 10% to 60% RH 1.8 Gy TID OPRM 4.4'C to 48.9'C (40'F to 120'F) 40% to 95% RH 100 Gy (Co-60 y) TID CENPD-400-P-A states that the addition of the new OPRM equipment and plant modifications for its installation should not produce unacceptable levels of noise emissions (electromagnetic interference) that could adversely affect adjacent equipment, or the licensee is to take action to prevent these emissions from reaching potentially sensitive equipment in the area of the OPRM installation. These measures apply for both noise susceptibility and emissions.
The staff finds that the licensee's evaluation of the electromagnetic interference (EMI) environment and the measures taken to shield surrounding equipment in order to reduce adverse EMI affects in the OPRM installation meets the staff guidance in Standard Review Plan Chapter 7 on EMI qualification, and therefore, they are acceptable.
3.5 Administrative controls In the SER for CENPD-400-P-A, the staff found the OPRM design features that control access to setpoint adjustments, calibrations, and test points to be acceptable.
The licensee states that administrative procedures willprovide controls for manually bypassing OPRM channels or protective functions when making setpoint adjustments and calibrations and willcontrol access to the bypass controls. These activities are acceptable to the staff.
3.6 Confirmation of Human Factors Review The licensee stated that the addition of the OPRM system annunciation windows to the indication panel did not require changes to this panel beyond the activation of existing annunciation windows and etching of the activated windows with the specific OPRM alarmed condition (e.g., 'Bypass/INOP,'Trip Enable,'Alarm'.
The licensee further stated that the changes were in accordance with the SSES human factors manual.
The staff finds this acceptable.
4.0
SUMMARY
Based on the above review and justifications for TS changes, the staff concludes that the licensee's OPRM implementation and associated proposed TS changes are consistent with the staff SER approving CENDP-400-P and appropriate guidance for design of digital instrumentation and control system modifications, and therefore, are acceptable.
5.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Pennsylvania State official was notified of the proposed issuance of the amendments.
The State official had no comments:
6.0 ENVIRONMENTALCONSIDERATION The amendments change a requirement with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and change the surveillance requirements.
The NRC staff has determined that the amendments involve no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure.
The Commission has previously issued a proposed finding that the amendments involve no significant hazards consideration, and there has been no public comment on such finding (63 FR 43210 and 63 FR 45528). Accordingly, the amendments meet eligibilitycriteria 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 amendments.
7.0 CONCLUSION
The Commission has concluded, based on the considerations discussed above, that:
(1) there is reasonable assurance that the health and safety of the public willnot be endangered by
'peration in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendments will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor: M. Waterman Date:
Bu1y 30,
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