ML20149B276
| ML20149B276 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 02/27/1981 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20149B274 | List: |
| References | |
| NUDOCS 8103130125 | |
| Download: ML20149B276 (5) | |
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NUCLEAR REGULATORY COMMISSION
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s,......s SAFETY EVALUATION uYTHE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO. 68 TO FACILITY OPERATING LICENSE NO. DPR-33 AMENDMENT NO. 64 TO FACILITY OPERATING LICENSE NO. DPR-52 AMENOMEM NO. 40 TO FACILITY OPERATING LICENSE NO. DPR-68 TENNESSEE VALLEY AUTHORITY BROWNS FERRY NUCLEAR PLANT, UNITS N05. 1, 2 AND 3 DOCKET NOS. 50-259, 50-260 AND 50-296 1.0 Introduction By letter dated March 1,1979 (TVA BFNP TS 122) and supplemented at our request by letter dated August 7,1979, the Tennessee Valley Authority (the licensee or TVA) requested amendments to Facility Operating License Nos. OPR-33, DPR-52 and DPR-68 for the Browns Ferry Nuclean Plant, Units Nos.1, 2 and The proposed amendments would revise the Technical Specifications appended 3.to the above Facility Operating Licenses to clarify calibration requirements for the Local Power Range Monitors (LPRMs), reduce the pressure at which scram time surveillance testing may be conducted and remove a preoperational start-up test requirement which has long since been completed and is no longer appropriate.
2.0 Discussion 40, 41, 47 and 48 for Units 1 and 2 and on The proposed changes on pages pages 39, 40, 46 and 47 for Unit 3 consist of adding an explanatory note to Table 4.1.8, changing LPPJi to APRM in 4.1 Bases, and changing 4.1 Bases for The purpose of these changes is clarification of LPRM-APRM requirements.
to correct previous typographical errors and to clarify LPRM calibration requirements.
The proposed change on page 124 of the Technical Specifications for Units 1 and 2 (page 128 for Unit 3) is to change the pressure at which the control rods may be tested. The present Technical Specifications require that "after each refueling outage, all operable (control) rods shall be scram time tested from the fully withdrawn position with the nuclear system pressure above 950 psig. TVA proposes to change the test pressure to 800 psig.
The proposed change would allow post refuel outage control rod drive scram timing to be conducted in parallel with the vessel hydrostatic leak test, thus saving about one day in the start-up test sequence.
The proposed changes on pages 240 and 241 of the Technical Specifications for Units 1 and 2 (pages 251 and 252 for Unit 3) is to delete section 4.7.C.la from the Technical Specifications and to reletter the remaining paragraph This specification is no longer applicable to Browns Ferry as from b to a.
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l all preoperational tests are completed and the requirement to test secondary containment integrity once per cycle is specified in 4.7.C-lb (to become 3
4.7.C-1a).
l 3.0 Evaluation 3.1 LPRM Calibration Table 4.1.B (p. 40 for Units 1 and 2, p 39 for Unit 3) lists the minimum calibration frequencies for the reactor protection system (SCRAM) instrument channels. This table specifies that the "LPRM Signal" is to be calibrated every 1000 effective full power hours using the TIP System traverse data.
The reason for this requirement and the time interval is explained in the bases.
"The sensitivity of LPRM detectors decreases with exposure to neutron i
flux at a slow and approximately constant rate. This is compensated for in the APRM system by calibrating every 7 days using heat balance data and by calibrating individual LPRM's every 1000 effective full-power hours using TIP traverse data." To clarify how this calibration is accomplished, TVA proposes to add a new explanatory note (Note 8) to 4.1.B which states:
"A complete TIP System traverse calibrates the LPRM signals to the process computer. The individual LPRM meter readings will be adjusted as a minimum i
at the beginning of each operating cycle before reaching 100% power." TVA also proposes to significantly amplify the bases (p. 48) for the calibration requirement to explain in more detail the procedures to be used to period-ically check the LPRM, APRM and process computer readings.
The proposed changes to the Technical Specifications do not change any present requirement nor the time intervals for perfonning the required calibration.
The purpose of the proposed changes are to clarify how the calibration has been accomplished and how TVA proposes to continue to meet the calibration requirement.
Based on our review of the licensee's submittal, we conclude that the modifi-cations to the Technical Specifications are correct, consistent with the requirements of IEEE Std. 279-1971, and therefore, are acceptable.
3.2 Scram Time Test Pressure As noted above, TVA proposes to change Section 4.3.C.1 of the Technical Spec-ifications to allow scram time surveillance testing to be performed at 800 psig rather than 950 psig as is now required.
In support of this proposed change, TVA has presented daca which show that scram time surveillance at the lower oressure is conservative, i.e., the scram time measured at 800 psig is greater than that at 950 psig. The licensee has presented data for the 20% and 90% control rod drive scram insertion points for four control rods from each of the three Browns Ferry Units. The 20% insertion point is the most significant to the limiting, pressurization transient. These insertion j
data also demonstrate that conservative scram insertion will be assured
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' through the range of scram position points. Based on our evaluation of scram time uncertsinties in Reference 1, we have concluded that these data show a systematic conservatism, i.e., the bias between the 800 and 950 psig measurements is substantially greater than scram time standard deviations.
Thus, the measurements at 800 psig would be a conservative representation of scram insertion times and effectiveness under transient conditions and for all scram positions.
We and TVA have reviewed the conduct of the vessel hydrostatic leak tett and have concluded that it would not affect scram time surveillance or vice-versa.
We conclude that the proposed change to the Technical Specifications is acceptable.
3.3 Preoperational Containme,nt Leak Test Section 4.7.C.1.a (P. 240 and 241) of the present Technical Specifications required that "a preoperational secondary containment capability [shall]
be conducted.....". This test was completed prior to startup of each unit to insure that secondary containment met the design objectives. To insure that secondary containment integrity is maintained during operation, Section 4.7.C.l.b requires that " secondary containment capability to maintain 1/4 inch water vacuum under calm wind conditions with a system inleakage rate of not more than 12,000 cfm shall be demonstrated at each refueling outage prior to refueling".
Inasmuch as preoperational requirements such as above are no longer apropos, our objective is to remove such requirements from the Technical Specifications. Accordingly, TVA has proposed to delete the obsolete Section 4.7.C.l.a and to renumber the current requirement from "b" to "a".
We conclude that the proposed action is appropriate and in keeping with our objective.
4.0 Environmental Considerations We have determined that these amendments do not authorize a change in effluent types or total amounts nor an increase in power level and will not result in any significant environmental impact. Having made this detennination, we have further concluded that these amendments involve an action which is insignificant from the standpoint of environmental impact, and pursuant to 10 CFR Section 51.5(d)(4) that an environmental impact statement, or negative declaration and environmental impact appraisal reed not be prepared in connection with the issuance of these amendments.
5.0 Conclusion We have concluded based on the considerations discussed above, that:
(1) because the amendments do not involve a significant increase in the probability or consequences of accidents previously considered and do not
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4-involve a significant decrease in a safety margin, the amendments do not involve a significant hazards considerations (2) there is reasonable assurance that the health and safety of the public will not be endangered i
by operation in the proposed manner, and (3) such activities will be con-ducted in compliance with the Commission's regulations and the issuance
- l of these amendments will not be inimical to the common defense and security or to the health and safety of the public.
Dated:
February 27, 1981 l
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. Reference 1.
Letter from T. A. Ippolito (USNRC) to D. Arnold (Iowa Electric Light and Power Company), September 4,1979, attached safety evaluation for Amendment No. 54.
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