ML20202E532

Compliance Evaluation Rept Approving Amend to Coc GDP-2

ML20202E532
Person / Time
Site:	Portsmouth Gaseous Diffusion Plant
Issue date:	11/26/1997
From:	NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS)
To:
Shared Package
ML20202E530	List: ML20202E524 ML20202E532 ML20202E541
References
NUDOCS 9712080068
Download: ML20202E532 (6)

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% y' o November 26, 1997 DOCKET: 70 7002 CERTIFICATE HOLDER: United States Enrichment Corporation Portsmouth Gaseous Diffusion Plant Portsmouth, Ohio

SUBJECT:

COMPLIANCE EVALUATION REPORT: APPLICATION DATED JULY 1,1997, AUTOCLAVE LOCKING RING PRESSURE

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' On July 1,1997, United States Enrichment Corporation (USEC) submitted a request to revise issue 3 of the Plan for Achieving Compliance with NRC Regulations at the Portsmouth Gaseous Diffusion Plant (PORTS) (Compliance Plan). The proposed amendment corrects the statements made in issua 3 of the Compliance Plan that depict the Autoclave Locking Ring Interlock System as having two redundant pressure " switches" set at +0.5 psig to prevent l the autoclave from being inadvertently opened while under pressure, in f act, the autoclaves have always had only one " switch" set at + 0.5 psig.

The existing Commitmeno e sction of Issue 3 of the Compliance Plan states:

"In addition to the safety systems summarized above, the following systems and limits are present to enhance safety

The Locking Ring interlock contains pressure limit switches which interlock with the hydraulic system to prevent opening the autoclave shell while under pressure (above 0.5 psig). Although only ..."

USEC has proposed to replace the phrase " pressure limit switches" with "a pressure limit switch."

The existing Justification for Continued Operation section of Issue 3 of the Compliance Plan states:

"4. ... alarm condition. Also, the autoclave locking ring interlock contains pressure limit

switches which lock out the hydraulics to prevent the autoclaves from being opened when the internal pressure is greater than 0.5 psig. The autoclave ..."

USEC has proposed to replace the phrase " pressure limit switches which lock" with "a pressure limit switch which locks."

Accordingly, the pertinent Safety Analysis Report (SAR) sections have also been modified to address this oversight made when the initial certificate application was submitted.

9712080068 971126 PDR C

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2 DISCUSSION PORTS uses thirteen cylindrical (6,7, and 8 foot diameter) steam autoclaves in buildings X-342, X 343 and X 344 to feed, transfer and sample UF6 contained in cylinders. These autoclaves were designed and constructed in accordance with ASME Section Vill and provide safety by confining UF6 and any reaction products in the event of a major UF6 release inside an autoclave. Steam used to heat UF6 cylinders within autoclaves is typically controlled at approximately 5 ps g. This pressure differentiai between the autoclave and the outside environment is maintained by way of a locking ring between the autoclave's l hydraulically movable shell and fixed head. An Autoclave Locking Ring interlock (ALRI) i system, which permits steam to be supplied to an autoclave only while it is closed, also contains a safety related pressure switch set at +0.5 psig, which prevents the opening of an autoclave while it has an internal pressure greater than 0.5 psig. This system protects workers, in close proximity to the autoclave, from steam burns and possible contamination in the event an autoclave is inadvertently opened while its internal pressure is greater than 0.5 psig. The ALR1 cystem includes another nonsafety related pressure switch set at 0.5 psig to prevent possible damage to the autoclave hydraulic system if the autoclave is opened at a significant internal vacuum. Figures 1 and 2 are schematic diagrams of typical feed, and sample and transfer autoclaves, respectively, t

Unconfinementmf_UFB, Steam and Raaction Products The ALRIis designed to protect workers from exposures to UF6 and its reaction products while they are in close proximity to a closed autoclave in which a large UF6 release has occurred, Such exposures could only occur following an inadvertent opening of the autoclave while it is pressurized with UF6 and its reaction products, in addition, the ALRI is designed to protect workers from steam burns while they are in close proximity to an inadvertently opened autoclave that is pressurized with steam, USEC has identified the ALRI systems, including the pressure switches and control relays, as Augmented Quality (AQ) systems. As such, USEC is required to apply a high level of quality control (portions of ASME NOA-1)in accordance with the Quality Assurance Plan approved by the NRC. Application of additional QA requirements to the ALRI augments the reliability of the system (no such failure events have been reported since March 3,1997). In addition, the interlocks are f ail safe in ; hat in a closed autoclave, an electrical interruption to the interlock would cause the pressure switch contact and the control relay contact to remain open, which in turn deactivates the hydraulic system keeping the locking ring from disengaging.

The UF6 containment boundaries provided by the cylinder, pigtail and valves inside an autoclave, and steam and UF6 reaction product confinement boundaries provided by the autoclave shel! . nd piping and valves out to and including the second containment valve, are designated as "O" systems. As such, USEC is required to apply the highest level of quality control (ASME NOA-1) to ensure that the pressure boundaries within these systems are maintained. Taking into consideration the applicable safety requirements (administrative and installed hardware) for preventing and/or mitigating UF6 releases associated with autoclaves, and past operational history at PORTS, the staff concludes that a major accidental release of UF6 inside a closed autoclave is highly unlike:y. However, in the event

3 of a large UF6 release inside a closed autoclave, the pressure risc would activate the autoclave containment system and the operators would be promptly alerted.

Therefore, the staff has concluded that having a single pressure switch in the ALRI set at

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+ 0.5 psig, as opposed to having redundant pressure switches, will not significantly increase i the risk of an inadvertent large release of UF6, steam or their reation products from the autoclave, OccupationaLRadiation_ Exposure Having a single pressure switch in the ALRI set at +0.5 psig, as opposed to having redundant pressure switches, will not significantly increase the risk of a large autoclave i release of UF6 nor would it measurably increase individual or cumulative occupational l radiation exposures. '

Criticality The staff has not identified any credible criticality accidents that these Complianco Plan and SAR changes may affect.

l Safeguards _andj3ecurity l

The staff has not identified any safeguards or security related implications from the proposed amendment.

ENVIRONMENTALREVIEW lssuance of the requested amendment to the Portsmouth Certificate of Compliance (GDP-2),

to amend TSR 2.1.3.5, is subject to the categorical exclusion provided in 10 CFR 51.22(c)(19) and will not have a significant impact on the human environment. Therefore, in accordance with 10 CFR 51.22(b), neither an environmental assessment nor an environmental impact statement is required for the proposed action.

CONCLUSION Based on the information provided in this CER, the NRC staff recommends approval of this amendment. Region ill staff have no objection to this proposed action.

Attachments:

1. Figure 1 Typical Feed Autoclave

2. Figure 2 Typical Sample / Transfer Autoclave ErincipaLContributor Yawar Faraz DISTRIBUT!ON-Docket 74 7002 NRC FILE CENTER PUBUC NMSS r/t NMSS Dr. Off. r/f FCSS r/f SPB r/f K'OBnen. Rlli CCox WSchwenk. FCOB PHiland. Rill DHartland. Ritt

• Sea prevenus enneurmnre CDC SP9 *SPB SP9,

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YFara DHnadley wi / /#

DATE U i k3f l97 7 19 7  % 19 7 ll /d /9 1 19 7 1 19 7 1 19 7 C = COVER E = COVER 8e ENCLOSURE N = NO COPY OMMD10CER.POR OFFICIAL RECORD COPY

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' autoclaves, and past operational history at PORTS, the staff concludes that a major accidental release of UF6 inside a closed autoclave is highly unlikely. However, in the event f a large UF6 release inside a closed autoclave, the pressuro rise would activate the toclave containment system and the operators would be promptly alerted.

The fore, the staff has concluded that having a single pressure switch in the ALRI set at

+ 0. 5 sig, as opposed to having redundant pressure switches, will not significantly increase the risk f an inadvertent large release of UF6, steam or their reaction products from the autoclav Occupationa . adiatiortExposure Having a single redundant pressur essure switch in the ALRI set at + 0.5 psig, as opposed to having switches, will not significantly increase the risk of a large autoclave release of UF6 nor und it measurably increase individual or cumulative occupational radiation exposures.

Criticality The staff has not identified an credihle criticality accidents that these Compliance Plan and SAR changes may affect.

Safeguarda_and3ecurity The staff has not identified any safegua s or security related implications from the proposed amendment.

ENVJRONMENTALREVJEW I

issuance of the requested amendment to the Por smouth Certificate of Compliance (GDP-2),

to amend TSR 2.1.3.5, is subject to the categoric exclusion provided in 10 CFR 51.22(c)(19) and will not have a significant impact in accordance with 10 CFR 51.22(b), neither an envin the human environment. Therefore, nmental assessment nor an environmentalimpact statement is required for the pro osed action.

CONCLUSION Based on the information provided in this CER, the NRC staff ecommends approval of this amendment. Region til staff have no objection to this propose action.

Attachments:

1. Figure 1 Typical Feed Autoclave

2. Figure 2 Typical Sample / Transfer Autoclave P2incipaLContributor Yawar Faraz DISTRIBUTION:

Docket 70-7002 NRC FILE CENTER PUBUC NMSS r/f NMSS Dir. Ott, r!f FCSS r>f WSchwint, FC08 PHdand, Rill SPB ri K'08nen, Rlli CCom

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CDC SPB b P9 SPD SPB NAME YFarneq Hoadley DMartin RPerun

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SATE l} # 2.0 r9 7 l1 r97 s 19 7 1 19 7 / 19 7 C = COVER / 19 7 / 19 7 E = COVER si ENCLOSURE N = NO COPY GMMD10CER.POR OFFICIAL RECORD COPY

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