ML19354D480

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Rev 1 to Safety Evaluation
ML19354D480
Person / Time
Site: Fermi DTE Energy icon.png
Issue date: 10/20/1989
From: Contoni J
DETROIT EDISON CO.
To:
Shared Package
ML19354D479 List:
References
89-0098, 89-98, DER-89-508, NUDOCS 8911090305
Download: ML19354D480 (10)
v • d • e


Text

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t l PART 1: DESCRIPTION OF GIAIRE (Preparer) l A) Document Identification l B) Revision l C) PIS Number I DER 89-508 i W/A l T4102 D) Description of Gian68 This Safety Evaluation is being written for the present plant configuration of the Control Center Heating, Ventilating and Air Conditioning (CCNVAC) and Standby Gas Treatment System (SGTS) ductwork as 1spected by DER 89-508. Continued on Page 2 E) List of affected UFSAR/TS sections: 9 4 and Appendir A and TS 3/4.7.2 eeeeeeeeeeeeeeeeeeeeeeee uweeeeeeeeeeeeeeeee:::::::::::::::::::::::::::::: l PART 2: SAFETY EVALUATION (Preparer) l A) Will the g--n2 change: Yes No [] [X)

1. Increase the probability or the consequences of an accident previously evaluated in the UFSAR?

[] [X)

2. Increase the probability or the consequences of a malfunction of equipment important to safety previously l

evaluated in the UFSAR? [] [X)

3. Create the possibility of an accident of a different type than any previously evaluated in the UFSAR7

( [] [X)

4. Create the possiblity of equipment malfunction of a different type than any previously evaluated in the UFSAR?

[] [X)

5. Reduce the margin of safety as defined in the bases for any technical specification?

Provide the basis for each answer above on a Continuation Sheet. B) Unreviewed safety question? Answer "Yes" if any of the above bones are checked "Yes." [ ] Yes [X) No C) Prepared by D. G. Jax / [ M Date /O-/7-89 uneueuunnununununeenn ::::::===:::::::::::::::::::::::::n l _ PART 3: REVIEW AND APPROVAL (Rvwr/Appvr/OSRO) l A) Reviewed b n A // .m4- -J. dJ/ o ro AJ i Date/8-li-89 I A Date /6)llf/M / ( "// M C) 05R0 Chairman Uik)$a Date Jo La-/1 "8 IKhE If an unre91ewed/ safety question is involved, or the proposed bu activjty also leads to the need for a change in the Technical Specifications, a review by the (.k NSRG and approval by the NRC, through a licensing amendment, is required before the proposed o7 act.tvity may be implemented. E l l Form FIP-SR1-01 Att 3 P1/1 112288 DTC: File: 1 _)

p l 7 4 SAFETI EVALUATION CONTINUATION SIEET Page 2 of /0 l

4) Enfoty Evaluation guaber i B) Rev i

89-0098 l 1 i h C) causesta l D) Description of Change (Continued) l . DER 89-508 involves structural and testing nonconformances with the i CCHVAC and SCTS ductwork. j Revision 0 of this Safety Evaluation was written shortly after the I deviation was discovered. Since then, Nuclear Engineering has completed a duct stress analysis and a detailed evaluation of both the CCHVAC and i SGTS ductwork and new industry guidelines for 10CFR50.59 Safety Evaluations (NSAC/125, June 1989) have been made available. This Safety Evaluation is being revised to reflect the duct analysis and evaluation, while using the new industry guidance for Safety L: valuations. I. Detailed description of DER 89-0508 r DER 89-0508 was written when Nuclear Engineering discovered that portions of control room emergency flitration systen ductwork do not conform to the design and testing requirements of ORNL-NSIC-65 (Oak Ridge' National Laboratory, Nuclear Safety Information Center). The UFSAR states that both the Control Center Heating, Ventilating, and Air Conditioning (CCHVAC) systen and the Standby Gas Treatment System (SGTS) ductwork was designed and tested in accordance with 2.8 of ORNL-NSIC-65 rather than ANSI N509-1976 as reconnended by Regulatory Guide 1 52. ( Portions of the ductwork on the suction side of recirculation filter i unit T4100D016 operate at pressures in the range of -12" to -17.8" of l water. For this ductwork: ORNL-NSIC-65 required Fermi 2 Present design 4 16 GA. sheet metal 18 GA sheet metal Pressure test -33" of water Pressure tested at +8" of water In addition to the non-compliance of ORNL-NSIC-65, Ferai-2's duct seismic analysis neglected the lapact of the extreme negative pressures. Saction 9.4.13 of the UFSAR states that the control center air conditioning system is designed to Category 1 requirements for both normal and energency operation. ORNL-NSIC-65 does not address seismic loading of doctwork. II. Impact of DER 89-508 on system operability A. CCHVAC - The following operability evaluation was prepared'in revision 0 of this Safety Evaluation. 'Ihis remains valid for revision 1 and is expanded on in Section III using the results of the detailed ductwork evaluation. Ferai-2's CCHVAC system is destgned with redundant active components (fans, dampers, chillers, etc.) and non redundant passive components (ductwork and filter trains). The ductwork is part of the flowpaths ( required by T/S 3/4.7.2 for Plant Operational Conditions 1,2,3,4,5 and when handling irradiated fuel in secondary containment. I I Fora FIP-SR1-01 Att 4 P1/1 062988

SAFET! ETALUATI(N (XWTINUATIM SEEt Pane 3 of /0 A) Safety Evaluation Bunker i B) Rev 89-0098 l 1 i ..( C) Comments (continued) The operable flow paths must be capable oft { (1) Recirculating control room air; i (2) Supplying osergency anke-up air to the control room. 7 f e he following discussion will state Ferai-2's basis for determining i that the ductwork (flowpaths) is operable for all applicable plant j operational conditions. t i i Fermi-2's CCNVAC systen has four modes of operations j f NDRIAL IIDDE i A small amount of air (approx. 10%) is mixed with recirculated air, bypassing the emergency filtration system. h is maintains the l control room slightly positive with respect to the outside ambient and the turbine building. t I i RECIRCLLATION IEIDE A maximum of 1800 CFM outside air is filtered and mixes with 1200 CFM l recirculated, air and is filtered again to provide continuous removal j of contaminants and to slightly pressurize the control room during a l radiological energency. ( CIEDRIIB 900E All outside intakes and exhaust flow paths are closed to prevent intrusion of chlorine in a chlorine release energency. A portion of the air in the control room is filtered through the energency recirculation filter. Maintaining the control room slightly positive l 1s not part of the chlorine mode design basis. PURGE MODE l 100% outside air is circulated through the control center and is exhausted to the atmosphere to purge any smoke or fumes within the control room. A elightly positive pressure in the control room is i not maintained, nor is it a requirement in this mode. The following demonstrates the ductwork operable: $d e Y Asen

1. A worst case bounding evaluation was performed to access the impact of the negative pressure on the existing seismic capability i

of the ductwork. The ductwork subjected to the worst negative operating pressure was evaluated (see Fig. 5). A negativn 17.8" of water internal pressure was applied to the existing seismic and dead weight analysis. ( l l i Fora FIP-SR1-01 Att 4 P1/1 062958

SAFETY ETALUATION 00NTINDATION SIENT Pate 4 of /0 A) Earety Evaluation Bumber l B) Ray 89-0098 l 1 a. D\\P e C) Comments (continued) The results indicate a maximum local reduction in cross sectional area of 6.6% during an earthquake coincident with pressure loading. Local reductions in cross-sectional area of this magnitude will have a negligible impact on the ability of the duct to perform as a flowpath. The ductwork panels are not breeched as a result of the new loading combination. All of the energency filtration system flows are automatically established by modulating dampers that control the control room pressure. The dampers will be able to compensate for the small flow resistances caused by local reduction in cross-sectional area. Tech. Spec. surveillances for the control room energ6ncy filtration system have an acceptance criteria of 1 05 for flow. 1 l 2. The ductwork has demonstrated satisfactory performance during start-up testing and plant operation, including the extreme negative pressures associated with the chlorine mode. 3 Nuclear Engineering has also looked at the pressure integrity of the filter housings (T4100D011 and D016) because of the extreme negative pressures. It turns out that the filter housings are designed in accordance with ORNL-NSIC-65 to 33" of water differential pressure. ( '!herefore, all of the flowpaths required by Tech. Spec. 3/4.7.2 are considered operable for all modes of CCHVAC and the applicable plant operational conditions. , GTS B. S Revision 0 of this Safety Evaluation concluded that the extreme negative portion of the SGTS ductwork was operable because it conformed to ORNL-NSIC-65. The detailed duct work evaluation revealed that portions of the ductwork were replaced in 1982 with a A lighter gage sheetmetal. The detailed ductwork evaluation CL.i (discussed in Section III) concludes that the present SGTS ductwork is operable, and thus the entire SGTS is fully capable of performing its intended safety function. l l III. Detailed Ductwork EvaluaMon - CCNVAC and SCTS p l Both CCHVAC and SGTS ductwork has been evaluated for compliance to ANSI N509, the standard presently endorsed by the NRC in Reg. Guide 1.52, I Revision 2 (DC-5089 and DC-5094 respectively). Included in the evaluation is a complete duct stress analysis that considers the following load combinations: l - Normal Operating - Internal pressure (woret case fan shut-off) plus dead weight. (- - Energency - Normal operating leads plus earthquake (this is considered worst case) I I Fora FIP-SR1-01 Att 4 P1/1 062958

_. -.=_ - j i l SAFTff RVALOATION CONTINUATION SEET Pane 5 of /0 A) Safety Evaluation Number i B) Rev i t 89-0098 l 1 I C) Comments (continued) The stress analysis concludes that the ductwork meets, the ANSI allowable stress for the normal operating case and the ducts would remain intact without compromising ultimate strength safety margins during an i energency. During an earthquake (coincident with pressure and dead l weight loads), some of the rectangular CCHVAC ducts experience local yielding at the corners, resulting in reductions in cross sectional flow l L area of no more than 105 No breach of pressure boundary is l experienced. The remainder of the CCHVAC and the SGTS ducts meet the ANSI allowable stress for the energency condition. As' indicated in Section II, local reductions in cross sectional area of this magnitude t will have a negligible impact on the ability of the duct to perform as a flow path. '!he automatic modulating dampers that control the control room pressure will be able to compensate for the small flow resistances i l caused these local reductions in cross sectional area, thus enabling the j entire system to perform as designed. t l-in Section II of this evaluation, the worst case bounding analysis on the extreme negative portions of the CCHVAC ducts concluded that the maximus e:oss sectional area reduction was 6.65. This was a specific duct stress analysis. The detailed evaluation that looked at the remainder of the CCHVAC ducts and the SGTS ducts used a much more conservative approach (rather than a specific stress analysis) and i concluded that the maximum reduction in cross sectional area would be I i less that 105. As stated earlier, in either case, area reductions of i this magnitude are acceptable. Also, as part of the detailed ductwork evaluation, all of the 1 requirements for duct construction and testing in ANSI N509 were reviewed line by line against Fermi 2's As-Built CCHVAC and SGTS ductwork. In some cases, due to the design and construction of the systems prior to the issuance of ANSI, Exact conformance is not attained. However, in all cases, conformance to the intent of the standard is accomplished. In conclusion, the duct work is fully capable of performing as a flow i path and both energency filtration systems will function as described + and evaluated in the safety analysis for all operational conditions required by the Technical Specifications. IV. Safety Evaluation 1. Since the structural analysis and detailed evaluation of the CCHVAC and SGTS ductwork has concluded that the ductwork is fully capable of performing as a flow path, both energency filtration systems will function as described in the UFSAR, the probability or the consequences of an accident previously evaluated in the UFSAR are not increased. ( I I I Fors FIP-SR1-01 Att 4 P1/1 062958

r SAFEff EVALDAT!W 00NTINUATION.WEET Pane 6 of 10 A) Barety Evaluation Busbor i B) Rev 89-0098 l 1 (. C) Comments (continued) 2. he stress analysis for the CCHVAC and SGTS ductwork concludes that the resultant stresses are less than the ultimate strength of the material for the maximum load combination of internal pressure, dead l weight, and earthquake excitation. This maximum load combination will cause some of the rectangular CCHVAC ducts to flesurally yield at the corners resulting in local reductions in cross sectional flow area of less than 105. 21s plastic deformation is structurally inconsequential and absolutely no breach of pressure boundary is experienced. It has also been determined that the small local reductions in cross sectional flow area in some of the CCHVAC rectangular ductwork will not Japact the ability of the system to provide temperature control L as well as a habitable environment in the control room. Furthermore, Feral 2's detailed line by line ANSI N509 duct evaluation has concluded that the as-built duct work complies with the intent of the ANSI standard in all areas of duct construction and testing. Since the performance of Fermi 2's CCHVAC and SGTS emergency filtration systems are not degraded below the design basis assumed in the accident analysis, the probability or the consequenoes of a Al ( ductwork malfunction has not increased. Ll 3 Since the stress analysis and ductwork evaluation has concluded that ductwork and the entire CCHVAC and SGTS emergency filtration systems will function as described in the UFSAR, the possibility of an accident of a different type than any previously evaluated in the UFSAR is not created. 4. The results of a worst case structural evaluation have been used to determine that the CCHVAC and SGTS ductwork will not malfunction. Both systems will perform as described in the UFSAR and the possibility of an equipment malfunction of a differently type than any previously evaluated in the UFSAR is not created. 5. This safety evaluation has concluded that the ductwork for both the SGTS and CCHVAC systems has not degraded the performance of the energency filtration systems below the design basis assumed in the UFSAR. Both systems will function as designed and within the margins of safety defined in the basis for the SGTS and CCHVAC Technical Specifications. C l l Forn FIP-SR1-01 Att 4 P1/1 062955

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