IR 05000206/1986031
| ML13323B178 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 07/08/1986 |
| From: | Carres M, Driscoll J, Willett D, Thomas Young NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | |
| Shared Package | |
| ML13323B177 | List: |
| References | |
| 50-206-86-31, NUDOCS 8607230339 | |
| Download: ML13323B178 (5) | |
Text
U. S. NUCLEAR REGULATORY COMMISSION
REGION V
Report N /86-31 Docket N License N DPR-13 Licensee:
Southern California Edison Company 2244 Walnut Grove Avenue Rosemead, California 91770 Facility Name:
San Onofre Nuclear Generating Station - Unit 1 Inspection at:
San Onofre Nuclear Generating Station Inspection Conduct : June 18-20, 23-24, 3 -July 2, 1986 Inspector: Willet,,:,e ctor Is or Date Signed Inspector:
riscoll, o
ltant A Date Signed Inspector: rnes,' co su nt ANL Date Signed Approved By:
. Young Jr. Chi Engine Th ction Date Signed Summary:
Inspection on June 18-20, 23-24, 30-Jul' 2, 1986 (Report Nos 50-206/86-31)
Areas Inspected Routine, annound n sction of licensee action on previous inspection findings regarding the Control Room Emergency Ventilation Syste Witnessing of'ventilation system testing to identify system. in-leakage and determine system flows and interaction with-adjacent boundaries'during various operating mode Results:
Of the areas inspected, no yiolations or deviations were identifie PDR ADOCK 05000206 G
DETAILS 1. Persons Contacted Licensee Personnel
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D.E. Nunn, Manager-of Nuclear Generation Services
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M.A. Wharton, Deputy StationManager
@ # M.P. Short, Unit-i Project Manager
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D.L. Johnson, Cognizant Engineer, Ventilation M.S. Tolson, Nuclear Safety Engineer
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T.A. Mackey Jr., Supervisor Compliance
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N.D. Nelson, Project Manager, Bechtel
@ # L.A. Bennett, Unit-i Licensing Engineer
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M.F. Freedman, Compliance Engineer
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G.T. Vechinski, Bechtel Engineer
- S. FreidP Bechtel NRC personnel
@ # J.J. Hayes, NRR Plant Systems Branch
@ # D.J. Willett, RVReactorInspector
@ # J.W. Dr clI,
~~utn Argonne Lab's Carnes, Consultant Argonne Lab's V Young, RV Engineering Section Chief
- R. Pate, RV Red ctr.Projects BrancBh Chief
J. Milhoan, NRR Plaht Systems Branch Chief
@#
J Dudley,*NRIRProjectoManager Ti# inJp ors also held discussions with other licensee and contract personnel during this inspection. These included licensed and non licensed operators, plant staff engineers, technicians, administrative assistants and Mqualityassurancepersone @
Denotes. those present.dringthe exit meeting on June 20, 1986.
Denotes those principals present during a series of teleconferences between June 24 and July 2, 198. System Measurements On June 18-20,23-24, 30-July 1, 1986, a region V inspector accompanied by two consultants from Argonne National Laboratories, witnessed licensee efforts to upgrade and verify system performance. The inspectors also took independent flow measurements of the Control Room (CR) and Technical Support Center (TSC) ventilation systems, while these systems were in the normal and emergency modes of operation. Data sets recorded were for the following combinations of operating modes (1) CR ventilation system in Normal, TSC system in Normal (2) CR ventilation system in Emergency mode, TSC system in Normal
(3) CR ventilation system in Emergency mode, TSC system in Emergency (4) CR ventilation system in Emergency mode, TSC Normal & Emergency systems secure In addition to the flow measurements taken with a hot-wire anomometer, differential pressure measurements were recorded across the control room to TSC, control room to outside, and TSC to outside boundaries with a differential pressure gauge and an inclined monomete The inspectors compared the flow and delta pressure measurements they took during the four operating configurations. The results of this comparisons verified the licensee's measurements which were submitted to NRR on June 29, 1986. NRR will issue their evaluation and recommendations in a report once they have completed a review of the licensee's system design, flow and delta pressure data, source term and assumptions utilized for control room dose calculation. Ventilation.System Repairs And Modifications The licensee identified and sealed many.sources of control room inleakag This inleakage was from duct work seams, approximately 50 penetrations between the control room and TSC, door seals and numerous fan housing leaks, one of which was approximately 2 inches by 8 fee The licensee blanked off the supply duct to the I&C Shop to increase the control room positive pressure margin. The register for this twelve inch duct was closed during previous NRC flow measurements. Additionally, blanking off this duct will preclude personnel from opening the register and upsetting the systems flow balance, since maximum register opening had the potential for very high flo The licensee installed a fire damper between the TSC and the hallway leading to the control room. This damper is positioned partially open so that the pressure differential between the TSC and the control room can be maintained at greater than or equal to 1/8 inch water gaug The licensee attempted to seal the return duct work which leads from the control room through the electrical switchgear room to the suction of the supply fa After the sealing the licensee blocked off the return ducting, and installed a special test setup to quantify duct leakage. This setup consisted of a fan supplying the duct work through a long straight run of temporary ducting with a variable opening in the return ducting. Initial leakage was.approximately 470 cfm. The licensee continued sealing leaks, and set off smoke bombs inside the ducting while pressurized to search for leakage. The licensee attempts to minimize leakage resulted in a final inleakage of approximately 250 cf. Charcoal Efficiency During a review of NRC concerns regarding charcoal filter efficiency, the licensee discovered that the system was designed for a 1/8 second filter residence time instead of 1/4 second that had been assumed and used for
testing by the licensee. The decrease in residence time results in a decrease in efficienc An additional concern regarding the moisture content of the ihplace charcoal was discussed with the licensee. The unit is subject to-hig humidity from the -atmosphere (ocean and drains in HVAC room).
The licensee intends to change out the existing potassium-iodide impregenated charcoal to a TEDA type of charcoal, which is more humidity resistant, soon after plant restart. In the time prior to plant restart the licensee has proposed to do testing which is acceptable to the NRC tha will demonstrate that the charcoal filters are not degraded due to moisture or will replace the present charcoal filter with new charcoa. Restart Criteria As a result of flow and pressure measurements taken by NRC in May (IE rp # 50-206/86-25 ) and after tel:econferences between Region V, NRR and SCE on June 4, 5, 10 and 11, 1986,-NRR provided SCE with the following four criteria for the restart of Unit-1:
1.U, Control roomemergency ventilation system charcoal adsorber is capable of removing at least 95 %-of the organic radioiodine.1 Cont rpY room operator thyroid doses are less than 30 Rem with dose assumptions specified in acceptance criterion 2 unless justified on a plant specific basi. Control.room envelope is maintained at a positive pressure with respect to all-. su'rounding boundarie.,
That unfiltered inleakage-to the control room envelope and the control room ventilation system ductwork be minimize NRR also provided the following guidance on how the four restart criteria can be satisfied Criteria Flow through the emergency filtration unit will be + or -
% of design flo Technical Specification 4.11.B.2 which will require that laboratory test on the charcoal be performed at 30 oC instead of 130 oC.with-a allowable penetration of 0.7 %'for methyl radioiodide. The Technical Specification change will not be required prior to.restar Criteria NRR will review SCE dose assumptions considering the use of respirators and thyroid blocking KI tablets. However this is not a long term solution and the licensee has been advised that these measures are not appropriate or meeting TMI Action Item III.D. Cri terion Periodic tests will be required to verify that the bontrol room envelope is pressurized to at least 1/8 in. water auge with respect to adjacent area Criterion Periodic tests will be required to verify' unfil tered inleakage based on. actual plant measurements.,
6. Exit Interview The inspection team met with representatives (denoted in paragraph 1) on June 20, 1986 and subsequent teleconferences. The scope and findings of the inspection, which were discussed during this meeting and teleconferences are summarized as set forth in paragraphs 1 through 5 of this report.