ML20129E150
| ML20129E150 | |
| Person / Time | |
|---|---|
| Site: | Crystal River  |
| Issue date: | 07/10/1985 |
| From: | Thompson H Office of Nuclear Reactor Regulation |
| To: | FLORIDA POWER CORP. |
| Shared Package | |
| ML20129E155 | List: |
| References | |
| NUDOCS 8507300266 | |
| Download: ML20129E150 (5) | |
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7590-01 UNITED STATES NUCLEAR REGULATORY COMMISSION In the Matter of
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FLORIDA POWER CORPORATION, ET AL
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Docket No. 50-302 (Crystal River Unit No. 3 Nuclear
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Generating Plant)
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EXEMPTION I.
The Florida Power Corporation (the licensee) and eleven other co-owners are the holders of Facility Operating License No. DPR-72 which authorizes operation of the Crystal River Unit No. 3 Nuclear Generating Plant (the facility) at steady-state power levels not in excess of 2544 megawatts thermal. This license provides, among other things, that it is subject to all rules and regulations and Orders of the Nuclear Regulatory Commission (the Commission) now or hereafter in effect.
The facility is a pressurized water reactor at the licensee's site located in Citrus County, Florida.
II.
On December 2,1981, the Commission published a revised Section 10 CFR 50.44, " Standards for Combustible Gas Control System in Light-Water-Cooled Power Reactors (46 FR 58484).
Section 10 CFR 50.44(c)(3)(iii) of the regulation requires:
"To provide improved operation capability to maintain adequate core cooling following an accident, by the end of the first scheduled outage beginning after July 1,1982, and of sufficient duration to permit 8507300266 850710 PDR ADOCK 05000302 P
i 7590-01 required modifications, each light-water nuclear power reactor shall be provided with high point vents for the reactor coolant system, for the reactor vessel head, and for other systems required to maintain adequate core cooling if the accumulation of noncondensible gases would cause the loss of function of these systems."
By letter dated October 12, 1982, the licensee requested an exemption from the requirement of 10 CFR 50.44(c)(3)(iii) to install a reactor vessel head vent.
Installation of high point vents at the top of the hot leg U-bends and the pressurizer for CR-3 was accomplished during the 1983 refueling outage. The licensee's justification for the exemption request, contained in the licensee's letter dated January 30, 1981, was based upon the ability to perform a plant depressurization to cold shutdown (following a small-break Loss of Coolant Accident (LOCA))
"even with a gas bubble in the reactor vessel (RV) head, without interrupting natural circulation".
In a letter dated April 29, 1983, the licensee committed to implementing procedures and training for use of the high point vents in venting noncondensible gases trapped in the reactor vessel head.
On July 21, 1983, the Commission issued an interim exemption to defer the implementation date for installation of a reactor vessel head vent until December 31, 1985. At that time, the Commission was unable to conclude that noncondensible gases could be safely vented by the hot leg
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i 7590-01 high point vents alone. The primary reason for the Commission's conclusion was the lack of integral system test data which would demonstrate the feasibility of the proposed venting procedure. The interim exemption was granted in order to allow the licensee to perform the necessary integral system testing.
On October 22, 1984, the licensee provided the results of testing performed in the Once-Through Integral System (OTIS) test facility which was performed to demonstrate that a reactor vessel head vent is not necessary to ensure adequate core cooling in the presence of significant quantities of noncondensible gases.
Based upon these test results, the licensee requested a permanent exemption from the requirement to install a reactor vessel head vent.
III.
The OTIS facility is an experimental test facility at Babcock &
Wilcox's (B&W's) Alliance Research Center in Alliance, Ohio. The OTIS facility was designed to evaluate the thermal / hydraulic conditions in the reactor coolant system and steam generator of a raised-loop B&W reactor, during the natural circulation phases of a small-break LOCA. The OTIS facility is a portion of the Integral Systems Test Program sponsored by the Commission, EPRI, B&W Owners Group and B&W.
The Commission has reviewed the OTIS test results and the licensee's proposed procedures and found that:
The hot leg vent can be used to remove noncondensible gases from the reactor vessel head during a plant cooldown and depressurization without interrupting natural circulation, i
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7590-01 Even if noncondensible gases in the reactor vessel head expanded into the hot leg U-bend and interrupted natural circulation, feed-and-bleed cooling can be used to assure core cooling.
In addition, opening of the hot leg vent will also allow the restoration of natural circulation.
Venting procedures have been developed to limit pas expansion rates from the reactor vessel head in order to ensure that 4
natural circulation is continuously maintained during a plant cooldown.
Procedures would specify initiation of feed-and-bleed cooling of the core, should natural circulation become interrupted, while attempting to recover natural circulation by leaving the hot leg vents open.
The reactor vessel head gas bubble which would remain following plant cooldown to actuation of the decay heat removal system will not interfere with core cooling. The licensee has developed various means to remove this gas bubble in the long term.
The OTIS tests were performed in a manner which assures that the results bound the expected CR-3 plant performance.
Based on the above discussion, we conclude that an exemption to 10 CFR 50.44(c)(3)(iii) can be granted. Details of the review may be found in the Commission's related Safety Evaluation dated July 10, 1985,
which is available for public inspection at the Commission's Public
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7590-01 Document Room, 1717 H Street, N.W., Washington, D.C., and at the Crystal River Public Library, 668 N.W. First Avenue, Crystal River, Florida.
IV.
Accordingly, the Commission has determined that, pursuant to 10 CFR Part 50.12, an exemption is authorized by law and will not endanger life or property or the common defense and security and is otherwise in the public interest and hereby grants an exemption with respect to the requirements of 10 CFR 50.44(c)(3)(iii), as follows:
The licensee is not required to install a reactor vessel head vent at Crystal River Unit 3.
Pursuant to 10 CFR 51.32, the Commission has determined that the issuance of the exemption will have no significant impact on the environment (50 FR 26422
).
This exemption is effective upon issuance.
FOR THE NUCLEAR REGULATORY C0 MISSION u h L. Thompso, Jr.
irector Di sion of Lic nsin Office of Nuclear Reactor Regulation Dated at Bethesda, Maryland this 10th day of July 1985