ML20217J947
| ML20217J947 | |
| Person / Time | |
|---|---|
| Site: | Portsmouth Gaseous Diffusion Plant |
| Issue date: | 08/07/1997 |
| From: | John Miller UNITED STATES ENRICHMENT CORP. (USEC) |
| To: | Paperiello C NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM), NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| References | |
| GDP-97-0141, GDP-97-141, TAC-L32014, NUDOCS 9708150087 | |
| Download: ML20217J947 (5) | |
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United St:les Entschment Corpot; tion 2 Democracy Centet 6903 nockledge Drive Bethesda, MD 20811 Tel (3011564 3200 rax:(301)564 3?01 l'aiited.%Ica
[sifichinctil ('ut p eralios JAMES H. MILT ER Dit (301)564 3309
%cE PRESIDENT, PnDDUCTroN Far (301) $71-8279 i
i August 7,1997 Dr. Carl J. Paperiello SERIAL: GDP 97-0141 j
Director Office of Nuclear Material Safety and Safeguards i
Attention: Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555 0001 Portsmouth Gaseous Diffusion Plant (PORTS)
Docket No. 70-7002 j
Response to Request for Additional Information
/
Certificate Amendment Request - Additional llypothetical Criticality Case for X 333 (SAR Section 4.1.1.2.3.5)
Dear Dr. Paperiello:
The purpose of this letter is to provide a response to the NRC's request (TAC. No. Ut2014) for additional information on the Certificate Amendment Request (CAR) dealing with the additional hypothetical criticality case for X 333. The request for additional information was provided to USEC in Reference 1 and identified additional infonnation required by NRC to allow final action to be taken on the subject Cenificate Amendment Request.
Enclosure I provides USEC's response to the request for additional information. USEC has reviewed (Detailed Description of Change) and Enclosure 3 (Significance Determination) which were previously transmitted in our February 13,1997 Certificate Amendment Request (Reference 2) and has detennined that the conclusions of these enclosures are still valid, b!!!,5l$lflh 08150087 970807 ADOCK 07007002 C
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I Dr. Carl J. Paperiello August 7,1997 GDP 97-0141 Page 2
'lhis submittal completes our response to the request for additional information (TAC No. L32014) provided to USl!C in iteference 1. Any questions related to this subject should be directed to Mr. Mark Smith at (301) 564 3244. There are no new comrnitments contained in this submittal.
Sincerely, q
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b pJames 11. Miller Vice President, l'roduction linclosure:
1.
Itesponse to Additional Information itequest, Additional llypothetical Criticality case for X.333 (SAll Section 4.1.1.2.3.5)(TAC No. L32014) cc:
NitC itegion til Ofrice NitC itesident insixctor - PODP NitC itesident inspector - PollTS DOllitegulatory Oversight Manager 1
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d Dr. Carl J. Palwriello August 7,1997 GDP 97-0141 Page 3 References I) NRC Letter from Yawar 11. Paraz to Mr. James 11. Miller,"Portsmouth Certificate Amendment Request - Increased Dose for Ilypothetical Criticality case in lluilding X 333 (TAC No.
L32014)" dated July 8,1997.
'!) US!!C 1.etter GDP 97-0014, Mr. James 11. Miller to Dr. Carl J. Paperiello, "Portsmouth Gaseous Diffusion Plant (PoltTS) Docket No. 70 7002 Certificate Amendment Request Additional llypothetical Criticality Case for X 333 (SAR Section 4.1.1.2.3.5)," dated February 13,1997.
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l linclosure I GDP 97 0141 Page 1 of 2 Response to AdditionalInformation Request Additional flypothetical Criticality Case for X 333 (SAR Section 4.1.1.2.3.5)
(TAC No. IJ2014)
Questionl Why did the increase in enrichment in the X 333 cascade result in a change in location of the assessed criticality accident? In principle, the reason is understood. Ilowever, a more explicit explanation is needed to show (*>.at the closest location was correctly identified.
Resonnel in the 19851/SAR analysis (Table 5,1.1 1), the enrichment gradient in the X 333 Process lluilding was evaluated based on an anticipated maximum enrichment of 1.33% in the building (although the actual building maximum was less than 2.3% enrichment). In this operational configuration, a cell with an enrichment greater than 1% U2"(i.e.,1.2 %) was approximately 240 feet away from the ACR in Unit X 33 8 and was chosen Ibr the postulated accident analysis. The increase in the maximum enrichment in the X-333 Process lluilding to 3% increased the number of units, from the case discussed in the SAR, where fissile enrichments could be present. As shown in SAR Figure 3.1.1.13, the ACR is in the middle (approximately) of the X 333 Ilullding, llased on the building gradient at a maximum enrichment in X 333 of 3%, the closest location to the ACR of process cell equipment with the potential lbr fissile enrichments is Cell 33 6 2. Utilizing existing building drawings, the distance from Cell 33 6 2 was detennined to be the hypotenuse of the triangle fonned by the height above the ACR to the cell floor and the ofTset distance from the edge of the process equipment to the edge of the ACR. This distance was slightly greater than 40 feet. A conservative distance of 40 feet was chosen since that distance corresponds to an entry in SAR Table 4.1.1-4, which allowed the dose resulting from a criticality event to be read directly from this SAR Table.
Qucationl What is the basis fbr assuming that the criticalities ofinterest occur in X 33 6 at 40 feet or at X 33 8 at 240 fect'?
Resonic The distance assumed was detennined by finding the distance to the closest process equipment boundary as discussed in the response to question I above, which contains fissile enrichments.
Conservatively, no attempt was made to determine locations with greater potential for a criticality accident; rather, the closest process equipment containing fissile UF. was chosen.
GDP 97 0141 Page 2 of 2 Qucillon.3 Show all steps in the calculation of 49 rem in ACR 1.
Euconse To arrive at the total dose of 49 rem, it was assumed that a criticality occurs in Unit X-33 6 within equipment closest to the ACR.I. Utilizing building drawings, the closest distance from Unit X-33 6 to ACR-1 was determined to be 40 feet, as discussed in the response to Question 1, above.
Utilizing building drawings, the shielding that exists between the postulated criticality location (X-33 6) and ACR 1 was detennined. Ilased on a cell floor thickness of 6.5 inches of concrete and an ACR roof thickness of 2 inches of concrete, as shown on the building drawings, it was conservatively estimated that the available shielding was equivalent to 8 inches of concrete.
Using a distance of 40 feet and an intervening shielding of 8 inches of concrete, the total dose read from SAR Table 4.1.1-4 is 48.28 rem. This value was rounded to 49 rem as the estimated dose which, as noted in the original CAR response, assumes that an individual rt aains within the ACR for the duration of the event. (Reference USEC Letter GDP 97 0014).
The assumptions utilized in generating SAR Table 4.1.1-4, which remain applicable to this evaluation, are described in SAR Section 4.1.1.2.3 and Appendix C.