ML20028H270
| ML20028H270 | |
| Person / Time | |
|---|---|
| Site: | Zion File:ZionSolutions icon.png |
| Issue date: | 11/14/1990 |
| From: | Taylor D COMMONWEALTH EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| GL-88-14, NUDOCS 9011190294 | |
| Download: ML20028H270 (3) | |
Text
Commonwaalth Edison D- - 1400 Opus PI:ce Downers Grove tilinois 60515 Dvember 14, 1990 U.S. Nuclear Regulatory Commissior, Attn:
Document Control Desk Hashington, D.C.
20555
Subject:
Zion Station Units 1 and 2 Supplemental Response to NRC Generic Letter 88-14 MRC_Docht.t Nos. 50-295/304
References:
(a) NRC Generic Letter 88-14, dated August 8, 1988.
(b) H. Richter letter to U.S. NRC, dated February 6, 1989.
Dear Sir:
Reference (a) requested that all holders of operating licenses or construction permits for nuclear power reactors review NUREG-1275, Volume 2, and perform a design and operations verification of the instrument air system.
Reference (b), which presented Commonwealth Edison's Company's (CECO) initial response to Reference (a), indicated that a response would be provided upon completion of the design verification for Zion Station.
This letter presents the results of the design verification for Zion Station Which was completed in 1989.
As indicated in Reference (a), Ceco determined that the design verification should address the following:
identify safety-related systems and equipment which use instrument air and/or nitrogen, review the manufacturer's air quality recommendations for the safety related equipment identified.
evaluate the design basis and failure modes, of the identified safety-related equipment, for technical adequacy.
review past and present testir,q (i.e., pre-operational, startup, inservice testing program, survtillances, etc.) to ensure proper performance of safety-related equipment upon loss of air, evaluate accumulator sizing to assure safety-related equipment will operate as designed.
review sefety-related air accumulator check valve applications and tests verifying design adequacy.
review air quality requirements (FSAR, Regulatory Guides, vendor
/ input),
review the. instrument air anomalies listed in NUREG-1275, Volume 2 for appilcability.
assess the potential for common mode failures (i.e.. due to poor air quality).
assess the failure of non-safety-related or reliability related systems on the performance of safety-related equipment using instrument air, and review the Braidwood Station loss of instrument air event for U
appitcability.
k 0o11190294'901114 PDR ADOCK 0500o295 P
9 b.S. Nuclear Regulatory Commission November 14, 1990 Edison was assisted in the design verification by the original design architect engineer for Zion Station.
The actions taken in addressing the objectives of the design verification are summarized below and documented in an engineering report being retained by Edison.
To facilitate the design verification, safety-related systems and equipment which use instrument air and/or nitrogen were identified and listed in a component matrix.
The component matrix, which tabulates information relevant to the design verification, is contained in the engineering report.
Manufacturers were contacted to determine air quaitty requirements for their equipment.
The majority of the vendors who responded have reiterated a requirement for clean, oil free air without quantifying these terms.
It has been determined that the air quality at Zion Station is not in conflict with the manufacturers' recommended air i
quality.
i The Inservice Testing Program (IST) and various operational surveillances were reviewed and evaluated to ensure sefety-related equipment will perform as expected upon loss of air and in accordance with all design-basis events.
Based on tests reviewed, no abnormalities were found.
All equipment was found to be adequately tested.
The information was evaluated to determine whether the designs are appropriate for the required function and whether the equipment wou!d be able to operate as designed.
It was concluded that there are no changes necessary to valve failure modes, or to accumulator sizing.
Accumulator check valve functionality is verified periodically by Station Procedure PT-2T. Accumulator sizing adequacy was verified by reevaluating the architect-engineer's calculation from the modification which installed the PORV accumulators.
The Technical Specifications and the Final Safety Analysis Report were reviewed to determine the quality requirements and we determined that specific quality requirements were not discussed.
- However, based upon recent testing, we have determined that the air quality at Zion Station is in accordance with Regulatory Guide 1.68.3 "Preoperational Testing of Instrument and Control Air Systems" which cites ANSI /ISA S7.3-1975 " Quality Standard for Instrument Air" as being "...an acceptable standard with respect to oil, water and particulate matter..."
The instrument air system anomalies listed in NUREG 1275 Volume 2 were reviewed for appilcability to Zion Station.
No significant concerns were identified as being applicable to Zion Station.
CECO determined that no improvements are necessary.
Common mode failures due to poor air quality would be a concern if i
the air quality was such that we would need to consider these types of potential failures.
However we are actively pursuing the maintenance of air quality at the level required to avoid common mode failures due to poor quality air.
l ZNLD369-17
' ' b.*S. Nuclear Regulatory Commission November 14, 1990 i
The failure of a non safety-related or reliability-related system that interfaces with instrument air systems would not be expected to impact the ability of a safety-related component to perform its design function.
This is based upon a postulated worst case scenario which would be a total loss of instrument air due to a failure of non safety-related or reliability-related system. A total loss of instrument air would cause the safety-related air users to perform per design (fail safe) causing a forced power reduction or plant shutdown.
CECO has reviewed the Braidwood Station event for applicability to Zion Station and has determined that no action is necessary.
As indicated in Reference (b), an instrument air quality monitoring program was implemented on a quarterly basis at Zion Station.
This program was found to be effective in monitoring and maintaining air quality.
It was determined that this program should be continued on a quarterly basis.
This correspondence completes the reporting requirements for Generic letter 88-14 for Zion Station.
Please address any questions concerning this response to this office.
Respectfully, D##2 D. L. Taylor Nuclear Licensing Administrator DT:
- ZNLD369-18 cc: A.B. Davis - Regional Administrator, RIII C. Patel - Project Manager - NRR Resident Inspector - Zion Subscribed and SworJn to before me this /V
' day of 2/tt.Lradt-
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Notary Public LYNN M. WLOD ARSKI NOTARY PUBUC, $1 ATE OF ILUN01S MY C0vvisst0N EXPIRES C/25/04
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