ML20151S591

Requests Enforcement Discretion Associated W/Potential Consequences of Returning Normetex Pumps to Operation in Product & Withdrawal Facilities

ML20151S591
Person / Time
Site:	Paducah Gaseous Diffusion Plant
Issue date:	08/28/1998
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-98-0188, GDP-98-188, NUDOCS 9809080250
Download: ML20151S591 (10)

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USEC A Glob,al Energy Company JAMES H. MILLER DIR: (301) 564-3309 VicE PRESIDENT, PRODUCTION fax: (301)571-8279 August 28,1998 GDP 98-0188 Dr. Carl J. Paperiello Director, Office of Nuclear Material Safety and Safeguards Attention: Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001 Paducah Gaseous Diffusion Plant (PGDP)

Docket No. 70-7001 Request for Enforcement Discretion

Dear Dr. Paperiello:

Pursuant to discussions held between United States Enrichment Corporation (USEC) and Nuclear Regulatory Commission (NRC) on August 28,1998, the purpose of this letter is to request enforcement discretion associated with the potential consequences of returning the Normetex Pumps to operation in the Product and Withdrawal Facilities. The enforcement discretion is necessary to allow cascade operations to return to normal pending the development I

and submittal for NRC approval of a Certificate Amendment Request to address this concern.

I PGDP Event Notification Worksheet No. 34693, dated August 26,1998, notified NRC that No. 2 Nonnetex Pump in C-315 tripped while running on stream. A discharge pressure of 46 psia was observed. This is greater than the TSR Safety Limit of 45 psia. The apparent reason for the

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pump trip was the closing of the discharge valve. There is a non-safety interlock designed to shut down the pump if the discharge valve closes. The pump was shut down and isolated by this l

interlock and was declared inoperable pending investigation and a technical evaluation in compliance with TSR 1.6.1.2.c. The automatic closure of the pump suction and discharge block valves limits the amount of UF, that can be released. The pump, when isolated, does not contain i

significant amounts of UF.. There was no release of UF.

6 98o9000250 980e28 PDR ADOCK 07007o01 C

PDR

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6903 Roddedge Drive, Bethesda. MD 20817-1818 Telephone 301564-3200 Fax 301-564-3201 http://www.usec.com Omces in Livermore, CA Paducah. KY Portsmouth. OH Washington. DC O

d Dr. Carl J. Paperiello August 28,1998

. GDP'98-0188, Page 2

. An engineering investigation into'the pump trip revealed that the Normetex Pump High j

Discharge Pressure Syste.m will not always function to meet the TSR operability requirements

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(TSR 2.3.2.1) for the Normetex Pump discharge bellows pressure.

r As a result of this discovery, all Normetex Pumps were declared inoperable on August 27,1998, j

and plant withdrawal operations were stopped. The cascade is currently in a Recycle mode. As

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i explained in Enclosure 1, USEC is seeking enforcement discretion to return to normal plant operations. Specifically, USEC is requesting discretion in the operability determination for the Normetex pump high discharge pressure system such that credit could be taken for the compensatory actions in restoring the system to TSR operable status. Enclosure 1 provides the j

technicaljustification for this request in accordance with NRC Inspection Manual Chapter 9900.

Should you have any questions regarding this matter, please contact Larry Jackson at

. (502) 441-6796 or Steve Routh at (301) 564-3251. Commitments contained in this submittal are

- identified in Enclosure 2.

Sincerely, James H. Miller Vice President, Production

Enclosures:

- 1. Justification for Request for Enforcement Discretion

. 2. List of Commitments cc: NRC Document Control Desk -

NRC Region III Office NRC Resident Inspector-PGDP Mr. Robert C. Pierson, NRC HQ

. Mr. Randall M. DeVault, DOE h

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ENCLOSURE 1 GDP 98-0188 Justification for Request for Enforcement Discretion l

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l GDP 98-0188 Page 1 of 6 1

JUSTIFICATION FOR NRC ENFORCEMENT DISCRETION i

1.

THE TSR VIOLATED.

TSR 2.3.3.1, Normetex Pump High Discharge Pressure System, will be violated. We can not demonstrate that the Normetex Pump High Discharge Pressure System will always function to meet the TSR operability requirements (TSR 2.3.2.1) for the Normetex Pump discharge bellows pressure.

2.

THE CIRCUMSTANCES SURROUNDING THE SITUATION, INCLUDING ROOT CAUSES, NEED FOR PROMPT ACTION AND IDENTIFICATION OF ANY RELEVANT HISTORICAL EVENTS.

The circumstances leading up to this issue are documented in PGDP Event Notification Worksheet No. 34693, dated August 26,1998. Specifically, the No. 2 Normetex Pump in C-315 tripped while running on stream. A momentary discharge pressure of 46 psia was observed. This is greater than the TSR Safety Limit of 45 psia. The apparent reason for the pump trip was the closing of the discharge valve. There is a non-safety interlock designed to shut down the pump if the discharge valve closes. The pump was shut down and isolated by this interlock and was declared inoperable pending investigation and a technical evaluation in compliance with TSR 1.6.1.2.c. The automatic closure of the pump suction and discharge block valves limits the amount of UF6 that can be released. The pump, when isolated, does not contain significant amounts of UF6. There was no release of UF6 and no discernable damage to the bellows.

The cause of the valve actuation is not known at this time, but is under investigation. The root cause of the circumstances leading to this noncompliance is indeterminate at this time; however, the investigation is underway.

Current plant condition is that the Product and Withdrawal facilities are in Recirculation with the Normetex Pumps in Mode 3 (i.e., not operating). The No. 2 pump in C-315 will remain shutdown until the TSR required technical evaluation and the root cause investigation are complete. The balance of the Normetex Pumps will remain in Mode 3 until the NOED is approved.

While in Recirculation, assay limits will increase significantly and the plant will have to commence assay mixing to prevent exceeding an assay limit. Freon gas will start pocketing in C-310 and will increase to the point that surges in the cascade will result and cascade shutdown with inventory is required to prevent compressor damage. These freon

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GDP 98-0188 Page 2 of 6 L

i perturbations and shutdown with UF inventory are an undesirable occurrence. In addition, 6

the cascade has never been operated in Recycle for more than several hours.

There have been no previous violations of the Normetex TSR Safety Limits reported. In

1991, one incident was recorded where the Safety Limit was marginally exceeded as indicated by an uncalibrated gauge. Other calibrated gauges did not detect or indicate the Safety Limit was violated. Based on this information, management concluded that no Safety Limit was violated.

3.

THE SAFETY BASIS FOR THE REQUEST, INCLUDING AN EVALUATION OF THE SAFETY SIGNIFICANCE AND POTENTIAL CONSEQUENCES OF THE PROPOSED COURSE OF ACTION, INCLUDING ANY QUALITATIVE RISK ASSESSMENT.

. SAR 4.3.3.1.1 defimes the accident scenarios for Normetex pump failures. The failure modes are def'med as a fatigue failure of the discharge bellows or outlet piping and a discharge pressure rise which ruptures the pump discharge bellows. The Normetex pump high discharge pressure system (TSR 2.3.3.1) will detect a high pressure and initiate shutdown of the pump prior to the pressure exceeding the LCS of 42 psia which is intended to prevent exceeding the Safety Limit. A failure of the Normetex pump high discharge pressure system would result in a source term bounded by the fatigue failure scenario described below.

The consequences of a fatigue failure are a UF release of 50 lb/ min for five minutes for a conservative total of 250 lbs. This is categorized as an extremely low hazard in accordance with SAR Table 4.2-2. This rate was conservatively derived from a withdrawal rate of 70,000 lb. UF / day. The release time of five minutes is based upon the UF release 6

6 detection system - Normetex pump (TSR 2.3.4.3) detecting the release, shutting down the pump and closing the discharge valve. Due to the close proximity of the detector heads,2 minutes would be a more realistic release time.

The safety significance of the operation with the requested discretion would be no greater than that presented in SAR 4.3.3.1.1 for a failure of the Normetex pump high discharge pressure system. The worst case release would still be bounded by the actions of the Normetex PGLD system to 250 lb. UF. The actual release would be significantly less.

6 Preliminary calculations indicate a release on the order of 3 lbs of UF. The initiating event 6

of a discharge valve closure does not rely on the PGLD system to isolate or shutdown the pump. The actuation of the 42 psia trip shuts down the pump. Therefore, should a release e

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occur at a pressure exceeding 45 psia, the pump has already tripped and would not continue

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to pump for the five minutes estimated by SAR 4.3.3.1.1.

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GDP 98-0188 Page 3 of 6 Th:, issue will have no impact on the criticality safety of the product withdrawal operations.

The proposed operation will have no impact on the release scenario. Therefore, the criticality safety of a UF release is unchanged. NCSA 3974-05 relies on the system 6

pressure being less than 50 psia to maintain moderation control in the product withdrawal condensers, accumulators and cylinders. The initiating event of concem for this issue, discharge valve closure, isolates the Normetex pump and any high pressure from the downstream product withdrawal system. The product withdrawal condensers, accumulators and cylinders are not exposed to the high pressure. Criticality is not a concern in tails withdrawal.

4.

THE BASIS FOR THE CERTIFICATE HOLDERS CONCLUSION THAT THE i

NONCOMPLIANCE WILL NOT BE OF POTENTIAL DETRIMENT TO THE PUBLIC HEALTH AND SAFETY, THE ENVIRONMENT, SAFEGUARDS, OR SECURITY, i

AND THAT NEITHER AN USQ NOR A SIGNIFICANT HAZARD CONSIDERATION IS INVOLVED.

The proposed operation will not result in risk greater than previously analyzed in the SAR.

The response in Question 3 shows the potential consequences are still bounded by the existing SAR analysis. The consequences presented in the SAR for the bounding analysis result in an extremely low hazard which is defined in SAR Table 4.2-2 as having no off-site impact, no health and safety concerns for workers at nearby facilities, and slight injury or illness to operating personnel. Therefore, there is no potential detriment to the public or worker health and safety.

l It is important to note that two redundant safety systems exist to prevent undue consequences of the postulated failures in the SAR. They are the PGLD system and the i

Normetex Pump High Discharge Pressure system. With the high discharge pressure system inoperable, the PGLD system will keep releases within those presented in the accident analysis.

The discovery of the Normetex Pump High Discharge System inability to prevent a Safety i

Limit violation is an as-found condition. The assumed margin of safety designed into the automatic features for the system never fully existed. The introduction of the compensatory actions discussed in item # 6 below, reestablishes the safety margin. Therefore, with the compensatory actions in place, no USQ exists.

Based on the following conclusions, there is no Significant Hazard Consideration:

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GDP 98-0188 Page 4 of 6

1. The proposed operation has no impact on any effluents released offsite. The actual operation of the withdrawal systems will be such that there is no change in the effluents emitted from these operations.

2. The proposed operation will not result in an increase in individual or cumulative occupational radiation exposure. The exposure to in process radiation will be the same.

Any exposure from released UF. is bounded by the SAR analyzed release of 250 lbs UF.

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3. The proposed operation will not result in a significant construction impact.

4. The SAR analysis has previously analyzed the accident of a failure of the Normetex high discharge pressure system. The proposed course of action is bounded by this SAR analysis. The consequences of a failure of the Normetex high discharge pressure system is stili bounded by the SAR analysis. Therefore, there is no increase in the potential for, or radiological or chemical consequences from, previously analyzed accidents.

5. There is no possibility of a new or different kind of accident.

6. The SAR analyzed accident scenario associated with this issue is the failure of the Normetex pump high discharge pressure system. In this scenario, the PGLD system detects the release, shuts down the pump and closes the discharge valve. No margins of safety associated with these mitigating actions are impacted by the proposed operation.

7. The proposed operation does not result in the possibility of a new or different kind of accident.

5.

THE BASIS OF THE CONCLUSION THAT THE NONCOMPLIANCE WILL NOT INVOLVE ADVERSE CONSEQUENCES TO THE ENVIRONMENT.

The proposed operation has no impact on any effluents released offsite. The actual operation of the withdrawal systems will be such that there is no change in the effluents emitted from these operations. In addition, no other operational activity will lead to increased environmental consequences.

6.

ANY PROPOSED COMPENSATORY MEASURES.

Operat onal procedurer were changed to maintain suction and discharge operating pressures i

such that de high dischage pressure system will meet the operability requirements of TSR 2.3.3.1. These procedures a e: CP4-CO-CN2021a," Operation of the C-310 Normetex Pump," and CP4-CO-CN2011b," Operation of the C-315 Normetex Pump."

A dedicated operator cr first line manager will be stationed and maintained in the ACR for C-310 and C-315 prior to placing the Normetex pumps into Mode 2 to ensure the procedure actions described above are implemented as appropriate.

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GDP 98-0188 Page 5 of 6 The interlock that trips the Normetex Pump motors upon closure of the discharge valve will

~be bounded and maintained as "Q." This interlock ensures the Normetex Pump motors do not continue to pump against a closed discharge valve, thus maintaining the assumptions of the procedure pressure limits. PGDP has initiated the change of safety system classification for the interlocks.

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THE JUSTIFICATION FOR THE DURATION OF NONCONFORMANCE.

By September 11,1998, USEC will submit an amendment request addressing the actions necessary for the ultimate resolution of this issue. The duration of this nonconformance will

- last until the NRC completes their action to approve the proposed amendment.

8.

A STATEMENT THAT THE REQUEST HAS BEEN APPROVED BY THE PLANT OPERATIONS REVIEW COMMITFEE (PORC).

The PGDP PORC approved this request for enforcement discretion on August 27,1998.

9.

THE REQUEST MUST ADDRESS HOW ONE OF THE NOED CRITERIA FOR APPROPRIATE PLANT CONDITIONS SPECIFIED IN SECTION B IS SATISFIED.

Criteria B.3 in Manual 9900 - NOEDs for GDPs states: "For all operating conditions at the GDP, the NOED is intended to avoid total plant shutdown, without cor sidering the full implication and without corresponding safety, safeguards, security or environmental benefit." Therefore, the granting of enforcement discretion would prevent a total plant shutdown and the introduction of additional risk caused by the abnormal evolution.

i In addition, USEC believes Criteria B.1 also applies to this situation. B.1 states: "For on-L going operations at the GDP, the NOED is intended to: (a) avoid undesirable transients as a result of forcing compliance with the TSR/ certificate condition and, thus, minimize potential I

safety, environmental, safeguards, or security consequences and operational risks; or,.."

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- We believe the cascade perturbations due to freon accumulation are undesirable risks.

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10. IF A FOLLOW-UP TSR/ CERTIFICATE AMENDMENT IS REQUIRED, THE NOED REQUEST MUST INCLUDE MARKED-UP TSR PAGES. THE ACTUAL TSR/ CERTIFICATE AMENDMENT REQUEST MUST FOLLOW WITHIN 48 HOURS.

Marked-up TSR pages are not available at this time because the ultimate resolution of this issue has not been determined. Submittal of the proposed TSR change is not expected until September 11,1998. This additional time is needed to completely question the basis of the 1

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TSR. We believe this delayed submittal is acceptable when considering the overall low L

safety significance of the issue and the effect of the compensatory actions proposed.

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11. ANY OTHER INFORMATION THE STAFF DEEMS NECESSARY BEFORE MAKING

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I A DECISION TO EXERCISE ENFORCEMENT DISCRETION.

t No'other infonnation has been requested by the Staff at this time.

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.4 GDP 98-0188 Page1of1 LIST OF COMMITMENTS Operational procedures were changed to maintain suction and discharge operating pressures such that the high discharge pressure system will meet the operability requirements of TSR 2.3.3.1.

These procedures are: CP4-CO-CN2021a," Operation of the C-310 Normetex Pump," and CP4-CO-CN2021b, " Operation of the C-315 Normetex Pump."

A dedicated operator or first line manager will be stationed and maintained in the ACR for C-310 and C-315 prior to placing the Normetex pumps in Mode 2 to ensure the procedure actions described above are implemented as appropriate.

The interlock that trips the Normetex Pump motors upon closure of the discharge valve will be bounded and maintained as "Q." This interlock ensures the Normetex Pump motors do not continue to pump against a closed discharge valve, thus maintaining the assumptions of the procedure pressure limits. PGDP has initiated the change of safety system classification for the interlocks.

On September 11,1998, USEC will submit an amendment request addressing the actions necessary for the ultimate resolution of this issue.

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