ML20198B304

Compliance Evaluation Rept Supporting Application Re Criticality Accident Alarm Sys Audibility Upgrades, Compliance Plan Issues 46 & 50

ML20198B304
Person / Time
Site:	07007001
Issue date:	12/07/1998
From:	Horn M NRC
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ML20198B287	List: ML20198B282 ML20198B304 ML20198B307
References
NUDOCS 9812180135
Download: ML20198B304 (3)

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g j NUCLEAR REGULATORY COMMISSION g f, WASHINoToN, D.C. 20SS4001 kg December 7, 1998 l DOCKET: 70-7001 l l CERTIFICATE HOLDER: United States Enrichment Corporation l Paducah Gaseous Diffusion Plant Paducah, KY

SUBJECT:

COMPLIANCE EVALUATION REPORT: APPLICATION DATED

NOVEMBER 5,1998, CRITICALITY ACCIDENT ALARM SYSTEM AUDlBILITY UPGRADES, COMPLIANCE PLAN ISSUES 46 AND 50 BACKGROUND By letter dated November 5,1998, the United States Enrichment Corporation (USEC) requested an amendment to Certificate of Complicnce GDP-1 for the Paducah Gaseous l Diffusion Plant (PGDP). The request was to revise Compliance Plan issues 46 and 50 to l change the completion dates. The request also included safety analysis report (SAR) changes l to reflect criteria for determining criticality accident alarm system (CAAS) audibility.

DISCUSSION Complianco Plan issue 46 involves a lack of audibility of the CAAS alarm hurns in certain areas of the plant process buildings due to high ambient noise levels. USEC was to complete the plant modifications neccssary to ensure that the CAAS alarm homs are capable of being heard throughout the affected areas of the process buildings by December 15,1998. Compliance Plan issue 50 involves the lack of alarm horns and lights in buildings located within the evacuation area of CAAS-covered buildings. USEC was to install evacuation horns and/or l lights for those unalarmed buildings that are located within the evacuation zone of an alarmed l building (200-foot zone) by December 15,1998. The homs and/or lights are activated f rom the CAAS-covered building. The Compliance Plan also allowed USEC to remove unalarmed buildings (such as trailers) from the evacuation area. All facilities which were planned to be relocated outside of the evacuation area of CAAS-covered buildings have now been relocated. USEC proposes to change the completion date for both issues to January 18,2000. The conceptional design for the process buildings originally required the installation of additional air i powered CAAS horns and upgrading the existing air system to supply the air necessary to power the new horns. Over the past year, the plant has experier,ced problems with the reliability of the air supply system to power the CAAS homs. Several event reports dealt with the inoperability of the CAAS due to the loss or degradation of the air supply. During the detailed design process, USEC questioned the reliance on the existing plant air supply to support the CAAS system and determined it to be undesirable. USEC now plans to utilize a

dedicated air system and air accumulators to supply the new CAAS homs. The same design i concept will be applied to all CAAS air horns at PGDP.

9812190135 981207 [ PDR ADOCK 0700 0 1

d 2 USEC proposes to continue using the same compensatory measures while the modifications are being completed. For example, the compensatory measure for issue 46 for the process buildings requires that the building howlers be sounded following actuation of any CAAS detection / alarm cluster. The howlers are hardwired to the CAAS and are activated immediately. Following a CAAS activation, procedures also require that a public address announcement be made to inform all plant personnel of the need for a building evacuation due to a CAAS activation. Issue 50 compensatory actions include postings installed to identify each unalarmed building within the evacuation area of an alarmed facility. Personnel entering those unalarmed buildings where the nearby criticality alarm horns cannot be adequately heard are required to have a radio capable of receiving emergency information, and personnel are required to monitor the radio continuously while inside the building. In the event of an alarm sounding, a page delivered over all radio frequencies will provide notification to personnel in the affected buildings and facilitate evacuation or other appropriate protective action. These measures provide assurance that personnel will be notified cf any activation of the CAA3 alarms and be able to take necessary protective measures. As part of the amendment request, USEC has also requested review and approval of two safety analysis report (SAR) pages that contain criteria for CAAS audibility (pages 2-6 and 2-15 of Chapter 4, Appendix A). ANSl/ANS 8.3-1986," Criticality Accident Alarm System," recommends

              . that the alarm signal should be of sufficient volume to be heard in all areas that are to be                             ;

evacuated and that the signals generated by the evacuation alarm system should be capable of producing an overall sound pressure level which is not lets than 10 dB above the overall maximum typical ambient noise level and in any case not less than 75 dB nor greater than 115 dB at the ear of the individual. The ANSI standard states thut field observations shall establish that the signal is audible above background throughout all areas to be evacuated and that personnel shall be notified in advance of an audible test. The standard does not provide any specific method for determining audibility. Because background noise in the process buildings at PGDP is high, there are some locations were audibility is questionable. USEC is proposing criteria to verify compliance with the audibility requirements. Audibihty is verified through a quarterly Technical Safety Requilement Surveillance. One method being proposed is to ensure the broadband CAAS alarm signal is at least 10 dB above the maximum expected broadband background noise. USEC would measure the sound levels. This criterion 1 is consistent with the ANSI standard. USEC is proposing to add two altemate criteria that can be used if criterion 1 cannot be met. Criterion 2 is to ensure the 1/3 octave 500 Hz CAAS alarrn signal is at least 13 dB above the maximum expected 1/3 octave 500 Hz effective masked threshold. This criterion has been taken from the internatior al Standard ISO-7731, ' Danger Signals for Work Places-Auditory Danger Signals." Criterion 3, which is also based on the International Standard, is to expose a minimum of ten people, representing a cross section of the plant population's age and hearing capabiiity, to the alarm signal and ensure each of the test subjects can hear the alarm signal. The test is repeated five times and is considered satisfactory if each of the test subjects can hear the signal each time they are exposed. The criterion differs from the Intemational Standard in that the standard requires that previous notice of the test not be provided to the subjects. However, the ANSI standard requires that any test be noticed in advance. Although criterion 3 is an acceptable method for showing that the CAAS audibility requirernents have been met, the test must somehow factor in the difference in noise levels at different cascade power levels. Because the background noise is greater at higher power levels, a test successfully conducted at low power levels would not suffice to demonstrate operability at higher power levels. This would generally only be an issue for tests i y _ - _ _ _ - _ _ _ _ .

_ _ __ _- _ _ . _ _. _ ~ . 3 r DEc.0150tt  : commIr months wh:n power 1:vtls aro frequ:ntly droppsd in respons3 to powsr demand, if l th3 t:st of crit:rion 3 is us:d, plant staff will need to assure that the power levels are not increased beyond the level for which the test was conducted to continue to consider the audibility function operable. The plant staff is aware of this requirement and only plan to use - this' criterion if audibility could not be established by using the first two criteria. The plant staff is evaluating methods to increate the noise level to the maximum expected levels during tests using criterion 3. Specifics for the tests of each criteria will be contained in plant procedures. Most facilities use subjective motheds for verifying the audibility of the CAAS alarms and do not measure the sound level. The proposed criteria provide a more objective method of verifying audibility. The staff notes that USEC submitted a separate exclusion request for the audibility requirements for confined spaces and cell housings on October 19,1998. The staff will act on that request as part of a separate action. ENVIROjiMENTAL REVIEW 4 issuance of an amendment to Certificate of Compliance GDP-1 to revise the completion dates

             'for Compliance Plan Issues 46 and 50 and to add audibility acceptance criteria to the SAR is subject to the categorical exclusion provided in 10 CFR 51.22(c)(19). Therefore, neither an environmental assessment nor an environmentalimpact statement is required for the proposed action.

CONCLUSION The staff concludes that the extension of the completion dates for Compliance Plan issues 46 l and 50 will not adversely impact the public health and safety. PGDP will continue to utilize the compensatory measures contained in the justification for continued operation for each issue. Although the staff is concerned that the CAAS audibility problems were not corrected on the original schedule, the staff does recommend that the Compliance Plan be revised to reflect the new completion date for issues 46 and 50. The staff also recommends approval of the criteria for determining CAAS alarm audibility as it provides a more objective method of verifying audibility. 4 The Region Ill Inspection staff has no objection to this proposed action. Erincioal Contributor Merri Horn t 70f NRC Rks BUC Rm V 3 Hlil YChen OFC SPD ( SPS / SPO , 2/ P, 8 NAME' 4 JMun ny ecson DATE [2 (2190 O/W /b M/9C _ C = COVER E = COVER & ENCLOSURE N m NO COPY OFMCIAL RECORD COPY =}}