ML20151Z655

Informs of NRC Intention to Exercise Discretion Not to Enforce Compliance W/Technical Safety Requirement 2.3.3.1 for Period from 980814,4:30 Pm Edt Until Issuance of Certificate Amend,Per Licensee Requests

ML20151Z655
Person / Time
Site:	07007001
Issue date:	09/01/1998
From:	Paperiello C NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS)
To:	John Miller UNITED STATES ENRICHMENT CORP. (USEC)
References
NUDOCS 9809220064
Download: ML20151Z655 (3)

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NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20556-4001 o

• % . . . . . ,o September 1, 1998 Mr. James H. Miller Vice President, Production U. S. Enrichment Corporation 2 Democracy Center 6903 Rockledge Drive Bethesda, MD 20817

SUBJECT:

NOTICE OF ENFORCEMENT DISCRETION FOR UNITED STATES ENRICHMENT CORPORATION (USEC) REGARDING PADUCAH GASEOUS DIFFUSION PLANT NOED NO. GDP 98-1

Dear Mr. Miller:

By letter dated August 28,1998, you requested that the Nuclear Regulatory Commission (NRC) exercise discretion not to enforce compliance with the actions required in Technical Safety ,

Requirement (TSR) 2.3.3.1, Normetex Pump High Discharge Pressure System. That letter l documented information previously discussed with the NRC in a telephone conversation on August 28,1998, at 9:00 a.m. Eastem Daylight Time (EDT). You stated that the plant wanted to l retum the Normetex pumps to Mode 2 (Withdr; wal) which would not be in compliar":e with TSR I 2.3.3.1 which requires the pumps to remain in Mode 3 (Standby) until the Normetex Pump High I Discharge Pressure System's operability is restored. You requested that a Notice of l Enforcement Discretion (NOED) be issued pursuant to the NRC's policy regarding exercise of I discretion for an operating facility set out in Section Vll.c, of the " General Statement of Policy and Procedures for NRC Enforcement actions"(Enforcement Policy), NUREG-1600, and be effective until the NRC issues an amendment to change the TSR requirements.

On August 26,1998, at 3:05 a.m. (EDT), the Building C-315 Normetex Pump No. 2 tripped while l running onstream due to an inadvertant closure of the discharge valve. Following the trip, the operators noted that the pump discharge pressure, during coastdown, rose to approximately 46 pounds per square inch absolute (psia), exceeding the TSR 2.3.2.1 -specified safety limit value of 45 psia. On August 27, your initialinvestigation of the trip determined that the Normetex pump high discharge pressure safety system trip design and operation would not be able to meet its intended safety function of preventing the Normetex pump discharge pressure from exceeding 45 psia. As a result, your staff placed all of the Normetex pumps in Mode 3, (Standby), a mode for which the safety system operability was not required. This re wir"i the cascade to be placed in the recirculation mode, which entails safety and economic cons plant shutdown, as discussed further below.

es which could lead to /)

The Paducah Safety Analysis Report (SAR) describes the accident of concern for the Normetex j1/I Q

pumps to be an overpressuring of the pump's discharge line expansion joint bellows. An over pressure event couid cause a rupture of the bellows resulting in a release of uranium hexafluoride (UFe). The SAR accident analysis bounds the accident consequences within those expected from a compete failure of the dischsge line and subsequent pump shutdown by another safety system, the Normetex UFe Release Detection Safety System. Section 4.3.3.1.1 of the SAR identifies the source term for a complete failure of the discharge line expansion joint bellows to be 250 pounds of UFe. Your staff calculated that the actual source term from a rupture caused by an overpressure event following an inadvertant closing of the discharge valve to be 3 pounds of UFe. Such a smal! release is of minor safety significance.

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2 Your request for enforcement discretion indicated thct operational procedure changes, to maintain the Normetex pump suction and discharge operating pressures at lower levels, and classification of a trip signal, generated by closure of the discharge valve, as safety related will prevent the 45 psia discharge pressure safety limit from being exceeded. Your NOED request also stated that by returning the Normetex pumps to Mov.e 2 (Withdrawal) with implementation of the described compensatory measures will not reduco me margin of safety and will not result in an unreviewed safety question. The NOED request further stated that prolonged operation of the cascade in the recirculation mode would result in an increased potential for both safety and economic conditions that would require a total shutdown of the cascade without a significant commensurate safety benefit. The referenced safety and economic consequences included an increased potential criticality risk, increased cascade perturbations due to the buildup of freon levels, and economic losses caused by a need to mix assay streams to limit the maximum cascade enrichment.

NRC recognizes that a release of UF, as a result of a rupture of the Normetex pump discharge expansion joint during pump coastdown following an inadvertant closure of the discharge valve is of minor safety significance, in addition, the release would be less than that experienced as a result of a total failure of the discharge piping which is mitigated by another safety system

.(Normetex UF Release Detection System). We agree that continued operation of the cascade in the recirculation mode, as required by the adherence to the Technical Safety Requirements for an inoperable Noremex Pump High [,ischarge Pressure Safety System, could introduce additional safety and economic consequences, including a total plant shutdown, without a corresponding safety benefit.

On the basis of the staffs evaluation of your request, including the compensatory measures described above and in your request for enforcement discretion, the staff has concluded that an NOED is warranted because we are satisfied that this action involves minimal or no safety impact and has no adverse radiological impact on public health and safety.' Therefore, it is our intention to exercise discretion not to enforce compliance with TSR 2.3.3.1 for the period from August 28,1998,4:30 p.m. EDT until issuance of a certificate amendment. This letter documents our telephone conversation on August 28,1Q98,4:30 p.m. EDT when we orally issued this notice of enforcement discretion.

However, as stated in the Enfocement Policy, action will normally be taken, to the extent that violations were involved, for the root cause that led to the noncompliance for which this NOED was necessary.

Sincerel tQd Y arl J. Paperiello, Director Office of Nuclear Material Safety and Safeguards l' Docket 70-7001 Certificate GDP-1 i

cc: Mr. Steven A. Toelle, USEC Mr. Randall DeVault, DOE Mr. Howard Pulley, PGDP DISTRIBUTION:

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also stated that by retuming the Normetex pumps to Mode 2 (Withdrawal) with implementation of e described compensatory measures will not reduce the margin of safety and will not result in an revie'wed safety question. The NOED request further stated that prolonged operation of the i casca in the recirculation mode would result in an increased potential for both safety and economi conditions that would require a total shutdown of the cascade without a significant l commensu te safety benefit. The referenced safety and economic consequences included an l increased pot tial criticality risk, increased cascade perturbations due to the buildup of freon l

levels, and econ ic losses caused by a need to mix assay streams to limit the maximum j cascade enrichmen . '

NRC recognizes that a re ase of UFe as a result of a rupture of the Normetex pump discharge I expansion joint during pump oastdown following an inadvertant closure of the discharge valve is of minor safety significance. I ddition, the release wou:d be less than that experienced as a l result of a total failure of the disc rga piping which is mitigated by another safety system '

(Normetex UFe Release Detection stem). We agree that continued operation of the cascade i in the recirculation mode, as require the adherence to the Technical Safety Pequirements for an inoperable Noremex Pump High Dis arge Pressure Safety System, could introduce additional safety and economic conseque es, including a total plant shutdown, without a corresponding safety benefit.

On the basis of the staffs evaluation of your requ t, including the compensatory measures

! described above and in your request for enforceme discretion, the staff has concluded that an NOED is warranted because we are satisfied that this ction involves minimal or no safety  ;

impact and has no adverse radiological impact on public ealth and safety. Therefore, it is our intention to exercise discretion not to enforce compliance ' h TSR 2.3.3.1 for the period from August 28,1998,4:30 p.m. EDT untilissuance of a certificat mendment. This letter documents our telephone conversation on August 28,1998,4:30 p.m. ED hen we orally issued this notice of enforcement discretion.

However, as stated in the Enforcement Policy, action will normally be t en, to the extent that violations were involved, for the root cause that led to the noncomplianc or which this NOED was necessary.

Sincerely, Carl J. Paperiello, Director Office of Nuclear Material Safety and Safeguards Docket 70-7001 Certificate GDP-1 cc: Mr. Steven A. Toelle, USEC Mr. Randall DeVault, DOE '

l Mr. Howard Pulley, PGDP DISTRIBUTION:

l Docket 70-7001 NRC File Center PUBLIC NMSS r/f FCSS r/f SPB r/f Rlli K. OBrien, Rill P. Hiland, Rlli M. Horn W. Schwink OFC SPB JPB , b \SFB QPp FCSS Riti ,. NMSS NAME C j O adley R rson ETen Eyck CPapenello DATE 8/M/98 8 19 8 8/ 98 8/ /98 ,8/ N98 8/ 19 8 l C = COVER E = COVER & ENCLOSURE N s NO COPY pjg/Q yu. M % / 4Qq[g l

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