ML20210T209
| ML20210T209 | |
| Person / Time | |
|---|---|
| Site: | Satsop |
| Issue date: | 09/25/1975 |
| From: | Harold Denton Office of Nuclear Reactor Regulation |
| To: | Deyoung R Office of Nuclear Reactor Regulation |
| References | |
| CON-WNP-1676 NUDOCS 8605290798 | |
| Download: ML20210T209 (3) | |
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i SEP 2 5 M75 R. C. DeYoung, Aseistant Director for Light Water Reactors, Group 1 RL EEVIEED HYDROLOCIC ENGINEERING INFUT TO SER FIANT NAME: WFFSS Nuclear Frojects No. 3 & 5 LICENSING STAGE: CP DOCEET NUMBER: 50-508, 509 MILESTONE NO.: 24-32 RESPONSIBLE BRANQI LWR l-3 REQUESTED COMPLETION DATE: Septeober 29, 1975 REVIEW STATUS: Hydrologic Engineering Section, Site Analyste Branch-Complete Enclosed is a revielon to Section 2.4.9 of our Hydrologic Engineering Seemary, dated June 27, 1975. The revisions are based on recently submitted amendments to the PSAR and resolve several outstanding issues. All other portions of the original submittal remain unchanged.
This revision was prepared by T. L. Johnson and W. S. Bivins.
Odghal SqnW h M.R.Destsa Harold R. Denton, Assistent Director for Site Safety Division of Technical Review Office of B'uclear Reactor Regnistion DISTRIBUTIGN:
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o' REVISED HYDROLOGIC LNCINEERlRG INPUT TO SER WPPSS NUCLEAR PROJECTS NO. 3 6 5 DOCKET NOS. 508 & 509 2.4.9 Groundwater Groundwater at the site region occurs predominantly in the alluvial aquifer underlying the Chehalis River Valley. The aquifer is fully saturated from chout 10 feet below ground level downward.
Recharge to the aquifer is from infiltration of precipitation and infiltration from the Chehalis River. The unconfined aquifer is about 2 miles wide and is horizontally limited by relatively impermeable sandstones on both sides of the river. Based on pumping test data, we conclude that an adequate supply cf nakeup water can be extracted from the aquifer, using the applicant's proposed groundwater collection system.
(See also Section 2.4.6).
In the immediate site vicinity groundwater occurs in the relatively impermeable sandstones of the Astoria formation. Recharge is derived from rainfall and snownalt along the topographic ridge south of the site above Uorkman Creek. The very loa permeability of the Astoria formation permits o'nly small amaunts of recharge and groundwater movement.
The applicant proposes to permanently louer the aroundwater levels in the vicinity of safety-related structures, using a systen of horizontal and vertical collector drains. The proposed syetem consists of vertical 6-inch half-round drain pipes, spaced on 8.5' centers around the reactor auxiliary buildings which collect and convey the groundwater to 8" horizontal drains located at mat level. The horizontal collector pipes discharge to a common (to both units) drainage tunnel which then conveys the flou into Workman Creek, south of the plant. The manholes, located at the corners of the auxiliary buildings, will be Category 1 and are to be designed to allow repair and maintenance in the event the system is clogged or damaged. In the event of total system failure, the applicant has estimated that there will be approxi-mately 1 1/2 to 4 months to repair the system before the ground-water level recovers to the design level of Elev. 350 msl (about 20 feet above the mat level). We conclude that these estimates are acceptable, based on independent evaluations of hydrologic parameters supplied by the applicant.
At our request, the applicant considered the ef fects of a f ailure of the circulating water pipe in or ualer the turbine building. The applicant states the released water would fill up the condenser pit and start to build up L the turbine building. Further, structural considerations would limit unter build-up to a depth of about I foot above the 8-inch high curb at the wall-floor interface. The vertical pipes of the groundwater
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&f ~ ~ 4 at }. 7 9 2-7 I drainage system will be Category I at the turbine building wall 3 . for a distance of approximately 4 feet above and below the turbiae building floor. -Since the tops of the pipes would be above the maximum water level inside the turbfna buf1 ding and since tha pipes.would not be perforated at this location,.we conclude that no' water will enter the groundwater drainage system.. Eased on independent evaluations, we further conclude that the failure of :the circulating water pipe outside of the turbine bailding will not overwhelm the groundwater drainage systed; due to the low permeabilities of site soils. At our request the applicant e aluated the effects of a postulated v rupture of'a liquid radwaste tank. The spill could move through cracks in the walls of the-auxiliary building into the groundwater drainage system. The applicant estimated that the size of-the cracks would limit the flow rate from the building to 50 gallons per day. Based on our independent evaluation,using.tluz above 1 information,we conservatively estimated the travel time tc the nearest uater user at the' mouth of Workman Creek to be approximctely 1 1/2 hours, and the total dilution factor at this user to be 5 approximately 2.3 x 10, L The applicant has committed to monitor groundwater icvals at the walls of the auxiliary building and to radiological monitoring of. discharges through the groundwater drainage system. The applicunt. proposes to install one piezometer at each auxiliary building wall, located halfway between the manholes and 10 feet from the wall. Instrunentation of the piezoneters will provide an alarm in the ' Control Room, if a specified level is exceeded. We conclude that the applicant's commitment.\\to monitor groundwater levels is acceptable; however, sih,ce more accurate groundwater parameters i .will be determined during construction excavation, we will review the final details of the monitoring system during the OL review, i' to determine the possible need for greater areal coverage in the water-level monitoring program. Based on our review of design parameters and data presented by the applicant, we conclude that the proposed groundwater drainage system is acceptable. However, we will require that the final design of the system be based on the more accurate groundwater para-i meters as determined during construction-excavation, if it is found that the current design bases are inadequate. Further, we l will require that the applichnt furnish the final design and the bases therefor for our' review and approval, prior to construction of the drainage system. i / e t / / i i I i E-i}}