ML14339A727
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PHYSICS TESTS Exceptions B 3.1.8 McGuire Units 1 and 2 B 3.1.8-1 Revision No. 115 B 3.1 REACTIVITY CONTROL SYSTEMS B 3.1.8 PHYSICS TESTS Exceptions BASES BACKGROUND The primary purpose of the PHYSICS TESTS exceptions is to permit relaxations of existing LCOs to allow PHYSICS TESTS to be performed.
Section XI of 10 CFR 50, Appendix B (Ref. 1), requires that a test program be established to ensure that structures, systems, and components will perform satisfactorily in service. All functions necessary to ensure that the specified design conditions are not exceeded during normal operation and anticipated operational occurrences must be tested.
This testing is an integral part of the design, construction, and operation of the plant. Requirements for notification of the NRC, for the purpose of conducting tests and experiments, are specified in 10 CFR 50.59 (Ref. 2).
The key objectives of a test program are to (Ref. 3):
- a.
Ensure that the facility has been adequately designed;
- b.
Validate the analytical models used in the design and analysis;
- c.
Verify the assumptions used to predict unit response;
- d.
Ensure that installation of equipment in the facility has been accomplished in accordance with the design; and
- e.
Verify that the operating and emergency procedures are adequate.
To accomplish these objectives, testing is performed prior to initial criticality, during startup, during low power operations, during power ascension, at high power, and after each refueling. The PHYSICS TESTS requirements for reload fuel cycles ensure that the operating characteristics of the core are consistent with the design predictions and that the core can be operated as designed (Ref. 4).
PHYSICS TESTS procedures are written and approved in accordance with established formats. The procedures include all information necessary to permit a detailed execution of the testing required to ensure that the design intent is met. PHYSICS TESTS are performed in accordance with these procedures and test results are approved prior to continued power escalation and long term power operation.
PHYSICS TESTS Exceptions B 3.1.8 BASES McGuire Units 1 and 2 B 3.1.8-2 Revision No. 115 BACKGROUND (continued)
The PHYSICS TESTS required for reload fuel cycles (Ref. 4) are listed below:
- a.
Critical Boron ConcentrationControl Rods Withdrawn;
- b.
Control Rod Worth;
- c.
Isothermal Temperature Coefficient (ITC); and These and other supplementary tests may be required to calibrate the nuclear instrumentation or to diagnose operational problems. These tests may cause the operating controls and process variables to deviate from their LCO requirements during their performance.
APPLICABLE The fuel is protected by LCOs that preserve the initial conditions of the SAFETY ANALYSES core assumed during the safety analyses. The methods for development of the LCOs that are excepted by this LCO are described in the Westinghouse Reload Safety Evaluation Methodology Report (Ref. 5).
The above mentioned PHYSICS TESTS, and other tests that may be required to calibrate nuclear instrumentation or to diagnose operational problems, may require the operating control or process variables to deviate from their LCO limitations.
The UFSAR defines requirements for initial testing of the facility, including PHYSICS TESTS. UFSAR Section 14.3 summarizes the zero, low power, and power tests. Requirements for reload fuel cycle PHYSICS TESTS are defined in ANSI/ANS-19.6.1-1985 (Ref. 4). Although these PHYSICS TESTS are generally accomplished within the limits for all LCOs, conditions may occur when one or more LCOs must be suspended to make completion of PHYSICS TESTS possible or practical. This is acceptable as long as the fuel design criteria are not violated. When one or more of the requirements specified in LCO 3.1.3, "Moderator Temperature Coefficient (MTC)," LCO 3.1.4, LCO 3.1.5, LCO 3.1.6, and LCO 3.4.2 are suspended for PHYSICS TESTS, the fuel design criteria are preserved as long as the power level is limited to 5% RTP, the reactor coolant temperature is kept 541°F, and SDM is within limit specified in the COLR.
The PHYSICS TESTS include measurement of core nuclear parameters or the exercise of control components that affect process variables.
Among the process variables involved are AFD and QPTR, which represent initial conditions of the unit safety analyses. Also involved are the movable control components (control and shutdown rods), which are required to shut down the reactor. The limits for these variables are
PHYSICS TESTS Exceptions B 3.1.8 BASES McGuire Units 1 and 2 B 3.1.8-3 Revision No. 115 APPLICABLE SAFETY ANALYSES (continued) specified for each fuel cycle in the COLR. PHYSICS TESTS meet the criteria for inclusion in the Technical Specifications, since the components and process variable LCOs suspended during PHYSICS TESTS meet Criteria 1, 2, and 3 of 10 CFR 50.36 (Ref.6).
Reference 7 allows special test exceptions (STEs) to be included as part of the LCO that they affect. It was decided, however, to retain this STE as a separate LCO because it was less cumbersome and provided additional clarity.
LCO This LCO allows the reactor parameters of MTC and minimum temperature for criticality to be outside their specified limits. In addition, it allows selected control and shutdown rods to be positioned outside of their specified alignment and insertion limits. Operation beyond specified limits is permitted for the purpose of performing PHYSICS TESTS and poses no threat to fuel integrity, provided the SRs are met.
The requirements of LCO 3.1.3, LCO 3.1.4, LCO 3.1.5, LCO 3.1.6, and LCO 3.4.2 may be suspended during the performance of PHYSICS TESTS provided:
- a.
RCS lowest loop average temperature is 541°F; and
- b.
SDM is within limit specified in the COLR.
APPLICABILITY This LCO is applicable in MODE 2 when performing low power PHYSICS TESTS. The applicable PHYSICS TESTS are performed in MODE 2 at HZP.
ACTIONS A.1 and A.2 If the SDM requirement is not met, boration must be initiated promptly. A Completion Time of 15 minutes is adequate for an operator to correctly align and start the required systems and components. The operator should begin boration with the best source available for the plant conditions. Boration will be continued until SDM is within limit.
Suspension of PHYSICS TESTS exceptions requires restoration of each of the applicable LCOs to within specification.
PHYSICS TESTS Exceptions B 3.1.8 BASES McGuire Units 1 and 2 B 3.1.8-4 Revision No. 115 ACTIONS (continued)
B.1 When THERMAL POWER is > 5% RTP, the only acceptable action is to open the reactor trip breakers (RTBs) to prevent operation of the reactor beyond its design limits. Immediately opening the RTBs will shut down the reactor and prevent operation of the reactor outside of its design limits.
C.1 When the RCS lowest Tavg is < 541°F, the appropriate action is to restore Tavg to within its specified limit. The allowed Completion Time of 15 minutes provides time for restoring Tavg to within limits without allowing the plant to remain in an unacceptable condition for an extended period of time. Operation with the reactor critical and with temperature below 541°F could violate the assumptions for accidents analyzed in the safety analyses.
D.1 If the Required Actions cannot be completed within the associated Completion Time, the plant must be brought to a MODE in which the requirement does not apply. To achieve this status, the plant must be brought to at least MODE 3 within an additional 15 minutes. The Completion Time of 15 additional minutes is reasonable, based on operating experience, for reaching MODE 3 in an orderly manner and without challenging plant systems.
SURVEILLANCE SR 3.1.8.1 REQUIREMENTS The power range and intermediate range neutron detectors must be verified to be OPERABLE in MODE 2 by LCO 3.3.1, "Reactor Trip System (RTS) Instrumentation." A CHANNEL OPERATIONAL TEST is performed on each power range and intermediate range channel prior to initiation of the PHYSICS TESTS. This will ensure that the RTS is properly aligned to provide the required degree of core protection during the performance of the PHYSICS TESTS.
PHYSICS TESTS Exceptions B 3.1.8 BASES McGuire Units 1 and 2 B 3.1.8-5 Revision No. 115 SURVEILLANCE REQUIREMENTS (continued)
SR 3.1.8.2 Verification that the RCS lowest loop Tavg is 541°F will ensure that the unit is not operating in a condition that could invalidate the safety analyses. The Surveillance Frequency is based on operating experience, equipment reliability, and plant risk and is controlled under the Surveillance Frequency Control Program.
SR 3.1.8.3 Verification that THERMAL POWER is 5% RTP will ensure that the plant is not operating in the condition that could invalidate the safety analyses. The Surveillance Frequency is based on operating experience, equipment reliability, and plant risk and is controlled under the Surveillance Frequency Control Program.
SR 3.1.8.4 The SDM is verified by performing a reactivity balance calculation, considering the following reactivity effects:
- a.
- b.
Control bank position;
- c.
RCS average temperature;
- d.
Fuel burnup based on gross thermal energy generation;
- e.
Xenon concentration;
- f.
Samarium concentration; and
- g.
Isothermal temperature coefficient (ITC).
Using the ITC accounts for Doppler reactivity in this calculation because the reactor is subcritical, and the fuel temperature will be changing at the same rate as the RCS.
The Surveillance Frequency is based on operating experience, equipment reliability, and plant risk and is controlled under the Surveillance Frequency Control Program.
PHYSICS TESTS Exceptions B 3.1.8 BASES McGuire Units 1 and 2 B 3.1.8-6 Revision No. 115 REFERENCES
- 1.
10 CFR 50, Appendix B, Section XI.
- 2.
- 3.
Regulatory Guide 1.68, Revision 2, August, 1978.
- 4.
ANSI/ANS-19.6.1-1985, December 13, 1985.
- 5.
WCAP-9273-NP-A, Westinghouse Reload Safety Evaluation Methodology Report," July 1985.
- 6.
10 CFR 50.36, Technical Specifications, (c)(2)(ii).
- 7.
WCAP-11618, including Addendum 1, April 1989.