ML20023C862
| ML20023C862 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 05/05/1983 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20023C853 | List: |
| References | |
| NUDOCS 8305180135 | |
| Download: ML20023C862 (4) | |
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UNITED STATES
..r g i NUOLEAR REGULATORY COMMISSION 3-wash NGTON. D. C.40555 f'
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- ...a SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT ND.57 TO FACII'ITY OPERATING LICENSE NO. NPF-3 TOLEDO EDISON COMPANY AND CLEVELAND ELECTRIC ILLUMINATING COMP'ANY DAVIS-BESSE NUCLEAR POWER STATION, UNIT 1 DOCKET NO. 50-346 1,0 Introduction The Safety Evaluation (SE) supporting Amendment lio. 23 to Facility Operating Lic'ense Ho. HPF-3, dated July 25,1980 (Reference 1), states:
" Additional requirements are necessary to minimize the potential for overpressure transients.
These include a requirement for a pressurizer bubble to exist in conjunction with the operability of DH-4849, a require-ment to vent the RCS if DH-4349 becomes inoperable, and a special rep;rting requirement if the overpressure protection systen is ever challenged".
By application dated December 26, 1980, the Toledo Edison Company (TED) proposed Technical Specification (TS) modifications which respond to the additional requirements identified by the HRC staff, i
2.0 Backcround The Davis-Besse low temperature overpressure protection system consists i
l of both active and passive subsystems.
The active subsystem uses r'elie'f
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valve (DH-4849) in the 4-inch suction line of the decay heat. removal (DHR) system to provide overpressure protection when the reactor coolant system (RCS) temperature is less than 280*F.
The passive subsystem is based on the. plant design and operating philosophy that prevents the plant from being in a water-solid condition (except for system hydrotests). The Davis-Besse RCS is always operated with either a ste~am or a gas space in the pressurizer; the steam bubble is replaced with nitrogen during plant.
cooldown when the RCS pressure is reduced.
3.0 Evaluation One o'f the additional requirements in the Amendment 23 SE was to vent the RCS if DH-4849 becomes inoperable and the RCS temperature is below 280*F.
This would be a single failure condition for an event where the High Pressure Injection (HPI) system is actuated or where the RCS makeup valve fails full open with a charging pump operating.
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l Instead of venting the RCS for these single failure events TED proposes to do two things:
8305180135 83050'5 PDR ADOCK 05000346
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- 1. - Ensure by operating procedures and TS's t, hat,.the' HP,I system 1s disabled.......
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when the RCS temperature is below 280*F.
2.
Have a TS which limits the water level in the pressurizer for a given RCS pressure to a level where the RCS pressure-temperature limit will not be exceeded if a charging pump pumps the entire content of the makeup water tank into the RCS.
These p'roposed provisions will effectively eliminate the possibility of an overpressure transient while the RCS is below 2800F as a result of inadvertent NPI system actuation or make-up valve failure with contin-uous make-up pump operation even if DH 4849 is inoperable.
Another requirement in the SE was to have a gas bubble in the pressurizer at all times while in operating modes 1 through 5.
To ensure a sufficient gas bubble while in operating modes 4 and 5, TED proposes to use the same pressurizer-water-level vs. RCS-pressure limit curves as used for the makeup valve failure e, vent.
The third and final requirement in the SE was for a special report if the
' low-temperature, overpressure protection system is ever challenged. Fo r this, TED. now has two reporting requirements in the Davis-Besse TSs. One is when the Emergency Core Cooling System, which includes the HPI system, is actuated and injects water into the RCS, TED has to prepare and submit a special report within 90 days. The second is that a Licensee Event Report (LER) has to be submitted whenever a TS is violated.
With the proposed new TSs, an overpressurization will not be possible without a violation of the TSs.
Therefore, TED will be required to submit a report if the overpressure protection system is ever challenged.
. We find that these proposed TSs are acceptable and satisfy the intent of the additional three requirements stated in NRC's ' Anendment Ho. 28 SE.
I We find that the Davis-Besse overpressure protection system meets GDC 15 and 31 and that TED has implemented the guidelines of.UUREG-0224. The Davis-Besse overpressure protection system is judged to.be an adequate solution to the problem of transients at low pressure.and temperature.
Environmental Consideration We have determined that the amendment does not authorize a change in effluent types or total amounts nor an increase in power level and will not. result in any significant environmenta), impact. -Ha' ing v
made this determination, we have further concluded that the amendment involves an action which is insignificant from the standpoint of environmental impact and, pursuant to 10 CFR 151.5(d)(4), that an environmental impact' statement, or negative declaration and environ-mental impact appraisal need not be prepared in connection with the issuance of this amendment...
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t DB-1 3-conclusion We have conclude'd,' based on the considera'tions discussed above. that:
(1) because the amendment does not invo1Ve a significant increase in the probability or consequences of an accident previously evaluated, does not create the possibility of an accident of a type different from any evaluated previously, and does not involve a significant l
reduction in.a margin of safety, the amendment does not involve a significant hazards consideration, (2) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, and (3) such. activities will be conducted in compliance with the Commission's regulations and the issuance of this amendment will not be inimical to the common defense and security or to the health and safety of.the public -
Dated: 11ay 5,1983 This Safety Evaluation was prepared by E. Lantz, Reactor Systems Branch.
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REFERENCES f
1.
USNRC; Safety Evaluation by the Office of Nuclear Reactor Regulation Supporting Amendment No. 28 to Facility Operating,
License No. NPF-3, Docket No. 50-346; July 25,1980; page 6.
2.
R. P. Crouse; Toledo Edison Company letter to the USNRC, R. W.
Reid, Chief, Operating Reactors. Branch No. 4, December 26, 1980.
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