ML19329B757

SER Input for Facility from Accident Analysis Branch

ML19329B757
Person / Time
Site:	Davis Besse
Issue date:	07/25/1975
From:	Ferrell C Office of Nuclear Reactor Regulation
To:
Shared Package
ML19329B756	List: ML19329B755 ML19329B757
References
NUDOCS 8002060768
Download: ML19329B757 (16)

Text

{{#Wiki_filter:- O-2.0 Site Characteristics 2.1 Geography and Demography The Davis-Besse site is a 954 acre tract of land located on the southwestern shore of Lake Erie in Ottawa County, Ohio. The site is approximately 20 miles east-southeast from Toledo, Ohio (popu-lation 383,818) and 20 miles west-northwest from Sandusky, Ohio (population 32,674) (Figure 2.1). The applicants have specified a minimum exclusion area distance of 732 meters (2400 feet) for the Davis-Basse reactor. The applicants have specified a low population zone (LPZ) with a radius of 3,218 meters (2 miles) Figures 2.2 and 2.2a show the exclusien area for the site. The topography of the Davis-Besse site consists of approximately 354 acres of flat shoreline and 600 acres of marshland, the latter leased to the U. S. Government as a national wildlife refuge. Figure 2.3 shows the present and projected year 2010 populations surrounding the Davis-Besse site. The population within the LPZ is about 1,958 using the 1970 census. The nearest population cen-ters (as defined in 10 CFR Part 100) with a present population e x-ceeding 25,000 are Toledo, Ohio (1970 population 383,818) and Sandusky, Ohio (1970 population 32,674) which are L ich located approximately 20 miles from the nuclear facility. The applicants have specified a low population zone of 2 miles. Because the popu-lation center distance is over one and one-third times the LPZ distance of 2 miles, the applicant's selection of the low population zone is in complicnce with 10 CFR Part 100. At the present time, the land surrounding the site is of a rural nature. Wildlife refuges cover a large section of the shoreline on both sides of the plant site. The closest industrial areas are four miles southeast of the site. Water sport activities in the area include pleasure boating, sport fishing, duck hunting and swimming. Lake Erie is used also for commercial fishing and shipping. The nearest Lake Erie potable water supply user is the Erie industrial park, located 3.6 miles from the Davis-Besse station discharge line. Agriculture is a major source of income in the vicinity of the Davis-Besse site. Major crops include peaches, grapes, apples, corn, wheat, soy beans, oats, hay, tomatoes, pumpkins, and sugar beets. According to the applicants, the Crane Creek State Park, located 3 miles from the site has an average daily summertime attendance of 2,500 and a peak attendance of 5,000. The Magee Marsh Wildlife Area located 2-1/2 miles from the site had an annual attendance of l 48,000 with a peak daily attendance of 1,500. l 80020607d8

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We have concluded that the adjacent land uses have been adequately considered and are not critical with respect to the safety of the plant. On the basis of the applicant's specified population center distance, minimum exclusion area and low population zone, our analysis of the onsite meteorological data from which atmospheric dilution factors were calculated (see Section 2.3 of this report), and the calculated potential radiological dose consequences of design basis accidents discussed in Section 15.0 of this report, we have concluded that the exclusion area, low populatiou zone, and population center distance meet the guidelines of 10 CFR Part 100, and that the Davis-Besse site is acceptable. 2.2 Nearby Industrial, Transportation and Military Facilities There are areas of Lake Erie adjacent to the Davis-Besse Nuclear Power Station site which are established as Restricted Areas for use by segments of the Armed Forces in performing training missions using ground weapons. Historically, these areas were primarily used by the Erie Ordnance Depot for proof firing of artillery. When the Erie Ordnance Depot was deactivated in 1967 and reverted to private ownership for development as the Erie Industrial Park, the main need for these Restricted Areas was removed but they have been_ =aintained, with several major reductions, for limited use of certain other agencies. These include Camp Perry, an Ohio National Guard installation and, until recently, the Naval Air Facility in Michigan and the Lockbourne Air Force Base in Ohio. In addition to these governmental agencies, the Cadillac Gage Company, located at the Erie Industrial Park, uses the offshore restricted areas under an arrangement with the Adjutant General, State of Ohio, for test firing of ordnance. The uses of these restricted areas were known and evaluated to determine the probable effect on the Davis-Besse Station at the time of the construction permit review. The Restricted Lake Areas as shown in Figure 2.4 (Areas I and II), with their closest boundary offshore from the station site and 1-1/2 miles from the station structures, are limited to use as impact areas for small arms, artillery, and antiaircraft artillery. Use of an area lying approximately ten miles north of the station (Area III), which, at the time of the construction permit review, was established for use by aircraft as an impact area for aerial gunnery, rocket firing, and bombing, has been discontinued and the designation of this area as a restricted danger zone area has been removed by the U. S. Corps of Engineers.

L ~ v 3- ~i Camp Perry is used for both small arms and 40 mm antiaircraft (equipped with a self-destroying fuse) ' firing with the nearest boundary of impact.at 1.5 miles from the Davis-Besse facility. Test firing at the Cadillac Gage Company includes mortars, cannons and automatic weapons. The nearest boundary of impact is 1.5 miles from the Davis-Besse site. A maximum of 10,000 pounds of high explosive equivalent is stored in approved bunkers in this area. On the basis of our review of the present use of these facilities, we -conclude that the present activities at these ranges have not changed,-since the construction permit review, in a way that would increase the hazard to the plant, and we conclude that these activities will not endanger the Davis-Besse Nuclear Power Station. i There are no oil or gas pipelines within 5 miles of the Davis-Besse site. The closest airport with a paved runway is at Port Clinton, 13 miles from the site. Because of the shallow-ness of Lake Erie in the area of the site, the nearest shipping l lanes are 20 miles from the site. The nearest ral. coad is th e Penn Central which runs in an east-west direction 5 miles south of the site. A spur line owned by the applicant which connects to the Norfolk & Western Railroad 7-1/2 miles southwest of the site has been constructed to serve the Davis-Besse Station. The closest highway is State Highway Route 2 located approximately 2,600 feet from the station structures. In view of the distances - to major transportation routes, we con-clude that transportation accidents involving hazardous materials -will not affect the safety of the nuclear facility. 3.5 Turbine Missiles .The applicant has arranged the Unit 1 tujbine generators in a non-peninsular orientation with respect to the containment. The ap-plicant has-performed an analysis to estimate turbine missile damage probabilities and has concluded on the basis of the results of the analysis'that the safety related systems are protected by . adequate structural barriers. We are currently performing a generic study and are formulating i a Regulatory. Guide on the matter of turbine missiles. When the results 'of our study are available, we will evaluate the signifi-cance.of potential turbine missiles on this facility and determine p r m. ..m_

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_4-if additional protection is required beyond that already offered by the presently proposed plant design. c.2.3 Containment Atmosphere Cleanup Systems In ai. tion to the heat removal function, the containment spray systes also functions to remove iodine. However, no iodine scrubbing additives to the containment spray have been proposed by the applicant. Consequently the iodine removal effectiveness of the containment spray system is not very pronounced. We esti-mate iodine removal coefficients of 0.06 hrs-1 and 0.2 hrs-1 for the elemental and particulate forms of iodine, respectively. These values are used in the accident calculations described in Chapter 15. 6.4 Habitability Svstems The emergency protective provisions of the control room related to the accidental release of radioactivity or toxic gases are evalu-ated in this section. Relevant portions of the control room venti-lation system are described here but are described and evaluated more fully in Section 9.4. 6.4.1 Radiation Protection Provisions The.. applicant proposes to meet General Design Criterion 19, Control Room, of Appendix.A to 10 CFR Part 50, by use of concrete sh ielding and a 3300 cfm charcoal filter to control radiation levels within the control room. In the event of high radioactivity af ter a LOCA, the normal control room air-conditioning system is shut down automatically and the emergency ventilation system is started manually. All outside air dampers are closed to minimi=e the dose to operating personnel. For the first four days following the accident, the emergency system will be operated in a fully recirculating mode where 3300 cfm of air is processed through the charcoal filter. On the fourth day, the system will be manually switched to admit 200 cfm of filtered outside air to the controi room with 3100 cfm being recirculated through the filter. We have calculated the potential doses to the operator after a design basis LOCA. We~ find that the present system adequately pro-tects the operator against whole body gamma and beta skin exposure. However we calculate a 68 rem thyroid dose which is in excess of the 30 rem guideline. The following parameters were used in cal-i culating the dose: l

1. Design basis LOCA. source term per Regulstory Guide 1.4 and the staffs' evaluation of plant safety features. 2. Atmospheric dilution factors (X/Q) from plant vent to isolated control room as given below: Time after LOCA X/Q, sec/m3 0-8 hours 3.16 x 10-3 8 - 24 hours 1.90 x 10-3 J-4 days 4.70 x 10-4 4 - 30 days 1.04 x 10-4 3. A filter efficiency of 95% for all iodine species, a filter flow rate of 3300 cfm and an unfiltered inleakage of 25 cfm. 4. Af ter four days, it was assumed that 200 cfm of filtered make-up air is admitted to the control room with 3100 cfm of control room air being recirculated through the filter and an unfiltered i inleakage of 5 cfm. 5. The resultant doses are presented below: Operator Thyroid Dose Time after LOCA (Rem)

• O-8 hours 29

'8 - 24 hours 25 1-4 days 10 4 - 30 days _]i Total 68

• Based on ICRP2 methods and a breathing rate of 3.47 x 10-4 m3/sec.

In addition to the non-compliance with the Criterion No.19 dose guidelines, the following deficiencies are noted: 1. The emergency filter units are not automatically activated upon a high radiation signal from air intake radiation monitors. Also it has not been verified that control room isiolation is accomplished f.omatically in the event of high radiaticn at tha intake. 2. The applicant has indicated that the control room is of low ?eakage design but has not committed to a periodic verifica-tion test. Periodic testing should be performed to verify that 209 cfm of make-up air will pressurize the control room to at l le.tst +1/8 inch water gauge differential with respect to all adjacent zones. He should also describe the seal design to be i

used for tu, doors leading into the control room and provide manufacturer's leakage data to show that the seal system provides adequate protection. We conclude that the present system dces not comply fully with our acceptance criteria as noted above. 6.4.2 Toxic Cas Protection Provisions Control room habitability following a postulated toxic gas release is required to insure that operators can continue to operate the, ut. Chlorine (30-ton railroad car) has been identified to be the on., material that, if released, would pose a potential operator hazard. The applicant was requested to provide protection against such a re-lease. He has partially complied with this request by supplying quick acting chlorine detectors, automatic control room isolation, and breathing apparatus. We have requested in our Q-2 positions that the applicant supply additional detectors at the chlorine storage location and that he provide additional breathing air for the respirators as per Regulatory Position C.4.c. of Regulatory Guide 1.95. Once the applicant commits to these additional items, then the plant's toxic gas protection will be acceptable. 1 15.4.6 Radiological Consequences of a Postulated Loss-of-Coolant Accident at Davis-Besse Unit 1: Containment Leakage Contribution J The radiological consequences of a loss-of-coolant accident as a result of leakage from the containment were evaluated. The analysis of the containment leakage doses following a postulated design basis loss-of-coolant accident included the influence of fission product removal and holdup systems.and the containment leakage routes on the estimated radiological consequences as well as appropriate conserva-tive assumptions relating to fission product releases and transport. This analysis of the proposed design results in calculated radio-logical consequences which do not conform to the Commission's regu-lations. Therefore, the applicant will be required - to take some positive measure, such as reducing the cgntainment design leak rat e to 0.3%/ day or less, to assure that the donservatively computed doses from a loss of coolant accident are within the exposure guidelines of'10 CFR Part 100. Estimates of the radiological consequences have been made using a containment leak rate of 0.3%/ day. Table I lists the assumptions used by the staff in determining these dose estimates, and Table II presents the results. ,w-e

TABLE I. ASSUMPTIONS USED TO ESTL%TE RADIOLOGICAL CONSEQUENCES DUE TO A POSTULATED LOSS OF CLJLANT ACCIDENT AT DAVIS BESSE UNIT 1 2772 Power level, Mwt 3 Operating time, years Primary Containment Leak Rate,* %/ day 0.3 to 24 hours 0.15 > 24 hours Fraction of Core Inventory Available for Leakage from Containment: 100% Noble Cases 25% Iodine Bypass Leakage Fraction, % of Primary Containment Leak Rate 0 - 2 mh utes 100. 2 minute.., to 30 days 3. 3 2.834 x 106 Primary Containment Free Volume, ft Iodine Form Fractions, % 91 Elemental Particulate 5 4 Organic Filter Efficiencies for Iodine Forms, % Elemental 95 Particulate 90 95 Organic Spray Removal Rates, per hour Elemental (Effective to 1.1-hours) 0.06 0.2 Particulate [ X/Q Values, sec/m3 5.4 x 10-4 0-2 hours @ 732 meters 1.8 x 10-5 0-8 hours @ 3200 meters 1.3 x 10-5 8 - 24 hours @ 3200 m-ters 24 - 96 hours @ 3200 meters 5.8 x 10-6 96 -720 hours @ 3200 meters 1.9 x 10-6

_a_ l TABLE II ESTDfATED CONSEQUENCES FROM A POSTULATED LOCA AT DAVIS BESSE UNIT 1 Doses, rem Thyroid Whole Body Exclusion Area Boundary (732 meters) 0-2 hours 200 17 LPZ Boundary (3200 meters) 0-8 hours 21 1 8 - 24 hours 11 0.4 24 - 96 hours 10 0.2 96~-720 hours 9 0.1 0 - 30 days 50 2 I c !~

- 15.4.7 Radiological Consequences of a Postulated Fuel Handling Accident at Davis-Besse Unit 1 The staff has evaluated the radiological consequences of a postu-lated fuel handling accident to any individual located at the nearest exclusion area boundary or at the outer boundary of the low population zone (LPZ). The staff concludes that the estimated consequences are well within the guideline values of 10 CFR Part 100. Table III presents the assumptions made and the estimated consequen-ces calculated for the fuel handling accident. O S l

TABLE III. ASSUMPTIONS FOR AND CONSEQUENCES OF A POSTULATED FUEL HANDLING ACCIDENT DAVIS BESSE TINIT 1 Power level 2772 Mwt Power Peaking Factor 1.7 ' Operating time 3 years Number of rods failed 208 Number of rods in core 38,816 Fraction of Inventory in gap: Noble Gases 10% Iodines 10% Effective Iodine Decontamination Factor in Pool 100 l Filter Efficiencies: Elemental Iodine 90% Organic Iodine 70% Iodine Fractions Leaving Pool Elemental 75% Organic 25% Shutdown Time 72 hours X/Q Values 0 - 2 hours 0 732 meters 5.4 x 10-4 sec/m3 0 - 2 hours-@ 3200 meters 3.7'x 10-5 sec/m3 I Estimated Consequences: Dose, rem Thyroid Whole Body Exclusion Area Boundary (732 meters) 22 2 LPZ Boundary (3200 meters) 2 <1

n. . TABLE IV ASSUMPTIONS FOR AND CONSEQUENCES OF A POSTULATED GAS DECAY TANK. ACCIDENT DAVIS-BESSE UNIT 1 Gas Decay Tank Rupture The assumptions used to calculate the offsite doses from a gas decay tank rupture were: (1) Gas decay tank contains one complete primary coolant loop inventory of noble gases resulting from operation with 1" failed fuel (94,000 curies of noble gases). (2) The release is complete within 2 hours. (3) Meteorological assumptions are the same as for the LOCA. Dose, Rem Estimated Consequences: Thyroid Whole Body Exclusion Area Boundary (752 meters) Negligible 3 LPZ (3200 meters) Negligible <1 O I l. i i <}}