[Federal Register Volume 59, Number 2 (Tuesday, January 4, 1994)] [Notices] [Pages 333-335] From the Federal Register Online via the Government Publishing Office [www.gpo.gov] [FR Doc No: 93-54] [[Page Unknown]] [Federal Register: January 4, 1994] ======================================================================= ----------------------------------------------------------------------- NUCLEAR REGULATORY COMMISSION [Docket Nos. 50-338 and 50-339] Virginia Electric and Power Company (North Anna Power Station, Units No. 1 and No. 2) Exemption I Virginia Electric and Power Company (the licensee) is the holder of Facility Operating License Nos. NPF-4 and NPF-7 which authorize operation of North Anna Power Station, Units No. 1 and No. 2 (NA-1&2, the facility) at steady-state power levels not in excess of 2893 megawatts thermal. The licenses provide, 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 employs pressurized water reactors (PWRs) located at the licensee's site in Louisa County, Virginia. The licensee is implementing a refurbishment and restoration program for the NA-1&2 service water system (SWS). The program is being conducted in several stages. The subject Phase 1, Stage 4 is to be conducted for a period of time beginning January 3, 1994 and ending October 13, 1994, and will be performed during dual unit operating conditions. The scope of Stage 4 involves restoration of the two 24- inch auxiliary supply lines from Lake Anna to the main SW headers. This consists of approximately 900 linear feet of piping (450 feet per line). Each 450-foot line consists of approximately 185 feet of direct buried piping, 230 feet of concrete-encased piping and 35 feet of exposed piping. To support the Phase 1, Stage 4 SWS restoration program, the licensee has identified one temporary exemption required at this time. The exemption is specified below. II The Code of Federal Regulations at 10 CFR part 50, Appendix A, General Design Criterion-2 (GDC-2) requires that: Structures, systems, and components important to safety shall be designed to withstand the effects of natural phenomena such as * * * tornadoes, * * * without loss of capability to perform their safety functions. The licensee has requested the temporary exemption from GDC-2 because of planned maintenance which will expose portions of the SWS piping to the potential effects of postulated missiles generated by natural phenomena. Earth and concrete protect the piping systems from the effects of severe weather events at the NA-1&2 site, such as tornadoes, for conformance with the requirements of GDC-2. The excavation of the auxiliary service water lines will affect only the missile shield protection aspects of GDC-2, with seismic qualification being retained. While producing a minimal increase in missile interaction risk, excavation of the piping does not result in total vulnerability to missiles. In the area of the planned excavation, the lines are substantially below grade and are adjacent to the turbine building structure. This will prevent some lateral aspects of missile vulnerability. The licensee is providing contingency measures with compensatory actions to provide added assurance of safe operation of the facility during the exemption period. Although the exemption is requested only for missile protection, the risk to the plant due to construction mishaps is more significant than the risk due to natural phenomena. Therefore, the compensatory measures are geared toward preventing such mishaps in addition to minimizing the potential for missiles generated by severe weather. As stated in the staff's Safety Evaluation dated December 27, 1993, these compensatory actions include but are not limited to the following:Electronic scanning and nondestructive locating methods will be used to accurately determine underground locations of piping, duct banks, and other buried utilities prior to excavation. Machine excavation will be limited to an elevation that does not pose a threat to the auxiliary service water (ASW) lines. The remaining excavation will be performed by hand operated power and manual tools. Physical barriers will be used to keep vehicles a safe distance from the excavation site. Loose materials in and around the excavation will be limited to only those absolutely necessary for activities in progress. Lifting and rigging components will be inspected and load tested. Lifting of equipment or construction materials over the excavation will be performed with adequate precautions in accordance with approved procedures. Direct verbal communication (using dedicated radios if necessary) will be maintained between equipment operators and supervisors/observers. Operable ASW lines will retain their seismic qualification. Engineering reviews will be performed for shoring and temporary supports (if required) in the excavation area. Gasoline powered equipment will be refilled using small containers and the number of containers within the excavation area will be restricted. This is in accordance with the existing station procedures. Worker training and shift briefings will be conducted for all aspects of the project. Severe weather procedures will be used to provide notification to clear the area of vehicles and loose materials in the event of a tornado watch or other high wind conditions. Adequate wind protection and heating will be provided during freezing weather conditions. Considering the existing design features and compensatory measures proposed by the licensee, the likelihood of damage to the exposed auxiliary SWS lines from postulated missiles generated by natural phenomena is minimal. Also, based on the compensatory measures provided, assurance exists that the ability to bring the plant to a safe shutdown will be maintained following any natural phenomena, including tornadoes or other severe weather which could result in airborne missiles. Therefore, there is reasonable assurance that the proposed GDC-2 exemption will present no undue risk to public health and safety. III The Commission has determined, pursuant to 10 CFR 50.12(a), that special circumstances as set forth in 10 CFR 50.12(a)(2)(v). The exemption would provide only temporary relief from the applicable regulation (GDC-2). The exemption is requested for a specific time period after which the facility would again be in conformance with all the requirements of GDC-2. The licensee has made good faith efforts in considering alternatives to the exemption requests and has concluded that the Phase 1, Stage 4 SWS refurbishment and restoration program can only be conducted without the subject exemption during a period when both NA-1&2 are shut down and defueled. The impact of scheduling such a dual-unit outage would have significant consequences in terms of power supply, fuel storage, capacity, and replacement power costs. Finally, the exemption will indirectly result in benefits to the public from increased reliability of the upgraded safety-related SWS. Based on the above and on review of the licensee's submittal, as summarized in the Safety Evaluation dated December 27, 1993, the NRC staff concludes that the likelihood of unacceptable damage to the exposed auxiliary SW lines due to tornadoe-borne missiles during the exemption period is low. Based on the low probability of unacceptable events, coupled with the comprehensive compensatory measures which the licensee has committed to, the NRC staff finds the proposed exemption from GEDC-2 acceptable. IV Accordingly, the Commission has determined that, pursuant to 10 CFR 50.12, the subject 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. The Commission further determines that special circumstances, as provided 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 regulations and that the licensee has made good faith efforts to comply with the regulations. Therefore, the Commission hereby approves the following exemption: NA-1&2 may operate without conforming to the requirements of GDC-2 as they apply to the buried portions of the auxiliary SWS lines from Lake Anna to the main SWS header providing that compensatory measures as described herein are continued for the period of the exemption. Pursuant to 10 CFR 51.32, the Commission has determined that granting the above exemption will have no significant impact on the quality of the human environment (October 7, 1993, 58 FR 52332). The subject Phase 1, Stage 4 SWS GDC-2 exemption is effective from its date of issuance through October 14, 1994. Dated at Rockville, Maryland this 27th day of December 1993. For the Nuclear Regulatory Commission. Gus C. Lainas, Acting Director, Division of Reactor Projects--I/II, Office of Nuclear Reactor Regulation. [FR Doc. 93-54 Filed 1-3-94; 8:45 am] BILLING CODE 7590-01-M