ML14183A385
| ML14183A385 | |
| Person / Time | |
|---|---|
| Site: | Robinson  |
| Issue date: | 11/12/1998 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML14183A384 | List: |
| References | |
| NUDOCS 9811170287 | |
| Download: ML14183A385 (3) | |
Text
1 AUNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C., 20555-0001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 180 TO FACILITY LICENSE NO. DPR-23 CAROLINA POWER & LIGHT COMPANY H. B. ROBINSON STEAM ELECTRIC PLANT. UNIT 2 DOCKET NO. 50-261
1.0 BACKGROUND
By letter dated March 6, 1998, as supplemented September 11, 1998, Carolina Power & Light Company (CP&L) requested Technical Specifications (TS) changes to permit the use of the post-accident monitoring (PAM) source range (SR) neutron flux detector as a compensatory measure in the event that one of the two required BF3 neutron flux detectors become inoperable during Mode 6 operations (refueling). The September 11, 1998, submittal contained clarifying information only, and did not change the no significant hazards consideration determination.
Specifically, the proposed change would modify TS Section 3.9.2, "Instrumentation," to allow core alterations and positive reactivity changes to continue, if one SR neutron flux monitor and PAM SR neuron flux monitor with control room indication is available, and if count rates from this indication are logged once every 30 minutes.
The Reactor Systems Branch (SRXB) review covered the neutronics and instrumentation aspects of this submittal. The Technical Specifications (TS) changes were reviewed independently by the TS Branch.
2.0 DISCUSSION AND EVALUATION During refueling (Mode 6), two operable BF3 SR monitors are required to provide redundancy during fuel movement or other actions that may cause positive reactivity changes, including removal of upper internal components. The proposed change would permit the use of the alternate PAM SR monitor in place of the primary BF3 SR neutron flux monitor. The change allows a PAM SR neutron flux monitor to be credited as a compensatory measure by providing indication redundancy for monitoring core reactivity in conjunction with the second BF3 SR neutron flux monitor.
The proposed change will maintain two BF3 SR monitors for visually monitoring core reactivity as currently discussed in the Bases for the affected TS. Audible indication provided by one BF3 9811170287 981112 PDR ADOCK 05000261 PD PFll
-2 SR monitor will still be required and will continue to be fulfilled by the remaining BF3 SR monitor. The PAM SR monitor is a fission chamber detector which has a sensitivity of 4 cps/neutron-volts (cps/nv) for thermal neutrons and a sensitivity of 2 cps/nv for fast neutrons.
The BF3 SR monitor, on the other hand, has.a sensitivity of 9 cps/nv. The PAM SR monitor has a comparable range and accuracy (i.e., range of 1 E-01 cps to 1 E+5 cps with an accuracy of 2% of full scale) to that of the BF3 SR monitor (i.e., range of 1 E-00 cps to 1 E+6 cps with an accuracy of 3% of full scale). Although the PAM SR monitor does not have the ability to provide audible count rate indication, the current TS require only one channel with audible count rate indication in the containment and the control room. This requirement will continue to be satisfied by the remaining BF3 SR monitor, and thus meets the TS Section 3.9.2 Bases requirements of six decades of indication and 5% accuracy. The licensee is required to perform a channel check every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> as per Surveillance Requirement 3.9.2.1, to ensure that the BF3 SR monitor is functioning according to design specifications. Since the H. B. Robinson's original licensing bases did not include the single failure criteria regarding the SR detectors, this amendment conforms with the original licensing bases.
This proposed change to the TS would result in a reduction in the redundancy of alarming capabilities since the PAM SR monitor does not have this capability. To compensate this reduction in redundancy of alarming capabilities, the proposed Required Actions would require compensatory measures in the form of logging the PAM SR indicated neutron flux every half hour. Also, redundant monitoring capabilities for core reactivity are available via administrative controls and physical limitations imposed on fuel handling operations, including a minimum of two visual control room indicators and an audible indication in the containment from the remaining BF3 SR monitor. Thus, this loss of redundancy is not considered to result in significant safety concerns and the changes to Required Actions and Bases adequately incorporate these changes to TS Section 3.9.2 and, therefore, are acceptable.
3.0 STATE CONSULTATION
In accordance with the Commission's regulations, the State of North Carolina official was notified of the proposed issuance of the amendments. The State official had no comments.
4.0 ENVIRONMENTAL CONSIDERATION
This amendment involves a change in the installation or use of a facility component located within the restricted area, as defined in 10 CFR Part 20. The NRC staff has determined that the amendment involves 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 amendment involves no significant hazards consideration, and there has been no public comment on such finding (63 FR 30262). 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 this amendment.
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5.0 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 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 the amendment will not be inimical to the common defense and security or to the health and safety of the public.
On the basis of the review described above, the staff finds acceptable the proposed changes to the H. B. Robinson Unit 2 TS 3.9.2 to allow the use of alternate SR detectors when one of the primary source range detectors (BF3) is inoperable.
Principal Contributors: A. Attard and Ram Subbaratnam.
Date: Noverber 12, 1998