ML20246H835

Exemption from Requirements of 10CFR50,App A,GDC-4 Re Effects of High Energy Line Breaks Outside Containment

ML20246H835
Person / Time
Site:	Crystal River
Issue date:	06/05/1989
From:	Varga S Office of Nuclear Reactor Regulation
To:	FLORIDA POWER CORP.
Shared Package
ML20246H829	List: ML20246H825 ML20246H835
References
NUDOCS 8909010385
Download: ML20246H835 (6)

Text

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7590-01 UNITED STATES OF AMERICA hDCLEAR REGULATORY COMISSION In the Matter of FLORIDA POWER CORPORATION, et al.

Do:ket No. 50-302 (Crystal River Unit 3)

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EXEMPTION 1.

Florida Power Corporation, et al. (FPC, the licensee) are the holders of facility Operating License No. DPR-72, whi:h cuthorizes operation of Crystal River Unit 3 (CR-3, tne facility) at steady-state power levels not in excess of 2544 megawatts theraal. The license provides, among other things, that the facility is subject to all the rules, regulations, and orders of the Nuclear Regulatory Commission (the Commission) now or hereafter in effect.

The facility is a pressurized water reactor (PWR) located at the licensee's site in Citrus County, Florida.

II.

10 CFR Part 50, Appendix A. General Design Criterion-4 (GDC-4) requires that structures, systems, and components important to safety be desiCned to accommodate the effects of postulated accidents, The structures, systems and components are required to be appropriately protected against dynamic effects, including missiles, pipe whipping, and discharging fluids that may result from equipment failures. At the time of licensing CR-3, the criterik employad by the licensee to analyze the effects of high energy line breaks (HELB) outside containment were consistent with th: staff's position as contained in the AEC 8909010585 890816 FDR ADOCK 05000302 ENCLOSURE P

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. letter dated December 22, 1972 from A. Giambusso. However, the. licensee ' reported recently that modifications involving safety-related equipment outside contain-q e

ment installed since that time were made without adequate consideration of HELB criteria.

III.

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.The licensee promptly embarked on a comprehensive program to identify all break. locations and safety-related systems and equipment which must function to mitigate the effects'of HELB events to ensure safe shutdown of the plant, and to protect such equipment as necessary.

FPC also performed an evaluation to show that continued operation of the facility while the identifiec deficiencies are being corrected does net constitute a threat to the health and safety of the public. The facility has been shut down fcr unrelated reasons during much of the time since identification of the HELB problem.

By letter dated December 16, 1988, as supplemented by letter dated.May 24, 1989, the licensee requested a temporary exemption from the requirements of GDC-4 with respect to consideration of the environmental and dynamic effects of HELB. The licensee requested that the exemption remain in effect until all actions, including hardware modifications, have been completed.

Because FPC's program nay include areas accessible only during shutdown, this was originally expected to occur no later than restart from Refuel 8, then scheduled during the fall of 1991. The staff considered this proposed exemption period to be exces-sive, and continued discussions with the licensee indictted that elements of its proposed schedule could be completed earlier.

In its letter of May 24, 1989, the licensee stated that completion in 1990 is anticipated. The first major schedule milestor.e, submittal of revised licensing and design basis criteria, was completed on March 31, 1989, on schedule.

In addition, refueling outages have been delayed 6 months, so that the next refuelin] outages will start

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3 approximately March 1990 (Refuel 7) and March 1992 (Refuel 8), rather than September 1989 and September 1991, as previously anticipated. The licensee has committed to review the program and schedules to determine what portion of the l

high energy piping can be protected during near-term plant operation in order to maximize full protection of safety systems at th9 earliest possible time.

It is believed that actions to protect most, if not all, systems important to safety against the effects of HELB can be completed by the end of Refuel 7.

There is reasonable assurance that the proposed exemption will present no undue risk to public health and safety becaut.e:

The likelihood of an HELS not previcusly analyzed and protected against in an area which could affect redundant safety systems required to mitigate that bieak is low. The licensee has reviewed the piping system stress analyses and has determined that the postulated terminal end break locations are not highly stressed and that breaks at these locations are low probability events.

In addition, the contribution of seismic loads to the potential for HELBs appears to be overstated because of the location of the facility in a seismically inactive area. Further, although new components (primarily potential targets) have been added, they are generally in areas where other principal safety system components are located which were analyzed as targets during original plant licensing, and therefore many potential HELB interactions with the new components are likely to have been adequately treated by features of the original design. With regard to the main feedwater system, the licensee's program in response to By11etin 87-01, Thinning of pipe Walls in Nuclear power plants, reduces the probability of an HELB in this

4 system. Also, the auxiliary steam line in the Auxiliary Building

- has been closed until permanent resolution of the HELB problem, leaving relatively few potential break locations in the Auxiliary l

Building.

Due to imposition of other criteria, such as electrical separai. ion and 10 CFR Part 50, Appendix R, Fire Protection, there is a reduced likelihood that one HELB con cause loss of safety function by impacting multiple trains of cafety equipment. Additional confidence in the survivability of. equipment required for reactor coolant system inventory contro? und the ability to shut down safely exists due to the previously pcMshted loss of the makeup function in each of 11 fire zones used during the 10 CFR Part 50, Appendix R review. Safe shutdown was demonstrated in each case, and since the effects of pipe breaks are more localized than those caused by a fire, the Appendix R analyses probably bound the HELB accident. The licensee also concluded that none of the identified breaks 'would prevent the makeup system from performing its inventory control function.

Decay heat can be removed using either the emergency feedwater (EFW) system or high pressure injection (HPI) system.

FPC has determined that no HELB event in the Intermediate Building can affect HPI, and that no HELB in the Auxiliary Building will affect EFW. Therefore, in the unlikely event of an HELB, removal of decay heat could be accomplished. Addt-.

tionally, since most plant modifications adding HELB targets were 6ssociated with the addition of automatic capability, the original manual capability to initiate safety functions should, in general, remain protected against an HELB.

Finally, plant procedures and i

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operator training regarding identification of leaks and compensatory measures in the event of an l'ELB will help in avoiding HELBs and if I

one should occur, in mitigating its effects.

This case involves special circumstances as set forth in 10 CFR 50.12(a)(v).

~ This exemption "would provide only temporary relief from the applicable regula-tions" (GDC-4). The exemption is requested fer a specific time period, after which the facility would be in conformance with the requirements of GDC-4.

Therefore, the proposed exemption would provide only temporary relief until the licensee' can permanently resolve identified deficiencies.

Since identification of the problem to the NRC, FPC has made good faith efforts to assure complete and expedited conformance to GDC-4. The licensee mounted a significant effort to identify all possible HELB targets.

A couplete program was defined to resolve the problem and the first important milestone has been completed. This action, preparation of pipe rupture analysis criteria, represents a significant effort to define HELB criteria to improve plant safety and reduce personnel exposure. The commitment to early protection of the maximum amount of safety equipment. as discussed above, is further evidence of FPC's good faith efforts.

IV.

Based on the above, and on review of the licensee's submittals to date, the hRC staff concludes that:

(1) the probability of an HELB which could dffect public health and safety is low, and (2) in the event of an HELB, it is likely that no loss of safety function would ou.ur and that the facility could be safely shut down. Therefore, the NRC staff finds the proposed exemption (with revised expiration date) from certain requirements of GDC-4 to Appendix A of 10 CFR Part 50 to be acceptable.

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i Accordingly, the Comission has determined that, pursuant to 10 CFR 50.12,

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this exemption is authorized by law, will not present an undue risk to the public health and safety, and is consistent with the common defense and security.

l The Comission further determines that special circumstances, as providea in 10 CFR 50.12(a)(2)(v), are present justifying the exemption, namely that~the exemption would provide only temporary relief from the applicable regulation and

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that FPC has made good faith effort to comply with the regulation.

Therefore, the Commission hereby approves the following exemption: The facility may operate without conforming to the requirements of GDC-4 with respect to the environmental and cynamic effects of HELB. This exemption shall I

expire by the and of Refuel 7, currently scheduled to begin in March 1990.

Pursuant to 10 CFR 51.32, the Comission has determined that granting 1

this exemption will have no significant effect on the quality of the human environment (June 5, 1989, 54 FR 24057).

l For further details with respect to this action, see the licensee's request dated December 16, 1988 and its submittal dated March 31, 1989, which are l

available for public inspection at the Comission's Public Document' Room, 2120 L Street, N.W., Washington, D. C. and at the Crystal River Public Library, 668 N.W. First Avenue, Crystal River, Florida 32629.

This exemption is effective upon issuance.

l FOR THE NUCL REGULATORY COMi!SSION l

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ar#, Dire tor Division of Reactor P cts I/II i

Office of Nuclear Reac -

Regulation Dated at Rockville, Maryland this 5th day of June 1989.

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