ML20211C475
| ML20211C475 | |
| Person / Time | |
|---|---|
| Site: | 07007001 |
| Issue date: | 09/15/1997 |
| From: | Pierson R NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | |
| Shared Package | |
| ML20211C458 | List: |
| References | |
| NUDOCS 9709260218 | |
| Download: ML20211C475 (4) | |
Text
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4 ;N a UNITED STATES j .
- j NUCLEAR REGULATORY COMMISSION
$' 's WASHINGTON. D.C, N5554001 k..... September IF,1997 DOCKET: 70-7001 CERTIFICATE HOLDER: United States Enrichment Corporation Paducah Gaseous Diffusion Plant Paducah,KY
SUBJECT:
COMPLIANCE EVALUATION REPORT: APPLICATION DATED APRIL 14,1997, AS REVISED JUNE 13, JUNE 23, AND AUGUST 18,1997, CASCADE CELL TRIP FUNCTION REQUIREMENTS BACKGROUNQ By letter dated %pril 14,1997, the United States Enrichment Corporation (USEC) requested an amendment to the certificate of compliance for the Paducah Gaseous Diffusion Plant (PGDP). The request is to revise the Technical Safety Requirement (TSR) concerning the cascade cell trip function. By letters dated May 23, and July 18,1997, the staff requested additional information. USEC responded to the request by letters dated June 13, June 23, and August 18,1997.
DISCUSSION USEC has proposed to revise TSR 2.4.4.12 concerning the cascade cell trip function.
Specifically, the TSR is being revised to provide clarification for battery cell parameters and to provide an alternate means of verifying functionality of the cascade cell trip circuit.
TSR 2.4.4.12 Limiting Condition for Operation, Condition E is bcing revised to clarify its applicability. Condition E requires that individual battery (cell) parameters be restored to within limits within 90 days. USEC has proposed a revision to Condition E to clearly indicate that individual battery (cell) parameters for any connected cell must be restored within limits. The TSR would not apply to disconnected cells. The battcries contain approximately 120 individual battery cells. Every cell in a given battery bank is not required to be connected in order to ensure that battery voltage is maintained at the prescribed value. USEC has stated that the load required to trip the air circuit breakers is less than 0.1 percent of the battery capacity. USEC based this determination on an engineering calculation of maximum trip coilloading for a unit of breakers. The trip coil loading was compared to the battery load rating to conclude that the electrical current load demanded of the batteries for the cell trip function was less thar 0.1 percent of the battery capacity.
The staff agrees that each and every battery cellis not necessary for the battery to perform its intended function to provide power to shutdown a cell. The intent was never to have the requirements apply to every battery cellindependent of whether they were connected to the battery bank. The proposed change just provides clarification on this subject. The staff notes that it would be considered inappropriate to disconnect a battery 9709260218 970915 PDR ADOCK 07007001 C PDR
2 celi (hat is out side the parameters to avoid restoring the battery cell parameters for that cell to within limits. ~ As discussed with USEC staff, she battery cell parameters should be restored.
USEC has also proposed an exception to TSR 1.6.2.2(d) for required Action E.1. TSR 1.6.2.2(d) prohibits entering an operational mode to which a TSR applies while relying on an LCO action. This exception would allow the plant to undergo mode changes during the 90 day period provided for restoring the battery cell parameters. Although not explicitly provided for in the TSR language, the staff understood that the cascade cells would undergo mode changes and did not intend to disallow mode changes while under LCO action E.
Surveillance Requirement 2.4.4.12 8 requires that for each planned cell shutdown, the ACR motor stop button is utilized for 00 and 000 cell shutdowns and that the motor breaker pistol grip at the local cell panel is utilized for C-310 cell shutdowns. This surveillance is used to functionally test the operability of the cell trip mechanism. This is the only surveillance specified in the TSR to test the cell trip mechanism. Cells cannot be started up without having met the surveillance and once shutdown there is no other r schanism provided to meet the surveillance requirement to allow restart.
At the time of transition from DOE to NRC jurisdiction on March 3,1997, a number of cells were down that had not been shutdown using the motor stop button. As these cells were already down, the TSR did not provide an alternate method by which to demonstrate operability. USEC hr.s proposed an alternate test to demonstrate operability that can be conducted on a shutdown cell. By letter dated January 24,1997, USEC had proposed this alternate test as a TSR clarification. By letter dated February 20,1997, USEC was informed by the staff that a clarification was not appropriate for this situation and a revision to the TSR should be considered. The alternative test would also be used to restart cells that failed the initial surveillance test or were shutdown by some other method.
The alternate test proposed by USEC depends on the type of cell being tested. For 00 cell motors, the reliability is demonstrated using the ACR motor stop button with the process substation transformer secondary breaker open and the motor breakers closed. Actuating the ACR push button will open the motor breakers thereby verifying the ACR trip circuit functions correctly. For 000 cell motors, reliability is demonstrated using the ACR motor stop button with the 15 kV Asir Circuit Breaker (ACB) disconnects open, process motor breakers open, and switch house 15kV ACB closed. Actuating the ACR push button will open the 15kV ACB thereby verifying the cell trip function. By verifying the ACR trip circuit functions correctly, there is reasonable assurance that the motors would have been de-energized if operating. The alternate test is equivalent for funct ional test purposes.
There is no alternative test for C-310 cells.
l The proposed revision to SR 2.4.4.12-8 would allow either functional test to be used to meet the surveillance requirement and demonstrate operability of the cell shutdown l
j mechanism. The original test would be used at the time of a planned cell shutdown; the alternative test, prior to rest t after a planned cell shut down. Use of either test is
! acceptable to the staff.
l
The proposed SR 2.4.4.12 8 in the April 14,1997, application contains a Note which states " Performance of this surveillance is not required for cell restart following an unplanned cell shutdown or for any cellin operation prior to or on the effective date of this TSR until the next planned cell shutdown." USEC stated that the SR is revised to clearly specify that the TSR does not apply to the two situations described in the note. The staff agrees that the TSR was never intended to apply to cell restart af ter an unp!anned shutdown; in fact, by the very nature of the surveillance, it would not be possible to conouct the surveillance on a shutdown cell. The staff is unaware of any issue that generated the need for clarification, but does not object to this aspect. The staff notes that there is some benefit to conducting the alternate test on cells shutdown in an unplanned manner but is not requiring it at this time. The staff does not agree with all of -
USEC's argument that the performance of the cell trip circuitry test prior to restart of shutdown cells (unplanned) could adversely affect the overall safety of cascade operations.
However, the staff has not requested that USEC include this feature in the TSR. The staff did indicate that USEC should consider the testing as a means to meet the Safety Analysis Report commitment for a 5-year frequency (see discussion below).
Tho second aspect discussed in the note was that the surveillance requirement did not apply for a cellin operation prior to the effective date of the TSR (assumed to mean Much 3,1997). There was no expectation by the staff that cells operating at the time of transition would need to be shutdown immediately just to meet the surveillance. To the extent that this was USEi. s concern, the staff agrees. However, it appears from the discussion provided with tqe amendment and the response to staff questions that the USEC intention in adding the language was to avoid shutting down operating cells on a 5-year frequency. The safety analysis report states that reliability of the manual cell shutdown system is verified through manual shutdown of each cell within a five-year period. A shutdown for the 5 year functional test would be considered a planned shutdown and would be expected to be covered by procedures. Although not a requirement in the TSR, the staff viewed the statement in the SAR to mean that cells are routinely shutdown in a planned manner every 5 years. However, USEC stated in its June 23,1997 response that it has never been PGDP practice to require shutdown of a cell on a 5 year cycle and that the time reference was merely provided to give a sense for how long a cell typically operates on a continuous basis between shutdowns. The staff views the 5 year frequency ior testing to be a commitment. However, as this was a commitment in the SAR and not in the TSH itself, this issue need not be resolved ir this amendment on the TSR. Additionally the SAR upgrade information is due later this year, and this issue may be better addressed using the information from the upgrade. As part of the June 23, 1997, response USEC provided a revised SAR page (4.312) that revised the language specifying a 5 year test frequency. USEC claims that the changes were made in accordance with 10 CFR 76.68 and are provided for information only. The staff has reviewed the 76.68 change package as a separate issue from this emendment and in fact has issued a Notice of Violation (NOV) to USEC in inspection Report 70 7001/97004.
USEC has not yet responded to the NOV. In the staff's July 18,1997 letter, USEC was asked to separate the issue of the 5 year frequency and the TSR changes by deleting the note from the TSR. In the August 18,1997 response, USEC agreed to separate the issue i and deleted the note. The staff is not reviewing or approving SAR page 4.3-12 as part of ;
this amendment action.
I l i l
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4 As part of the TSR change, USEC has also added a definition of planned and unplanned shutdowns to the Basis statement. Unplanned cell shutdown is defined as any automatic trip of the process motors. Planned cell shutdown is defined as the process of manually de-energizing the process motors in accordance with approved procedures. The staff understands this to mean that the procedures specify when a cell should be shutdown and is not intended to define the mechanism for shutdown. The definitions are acceptable.
E_NVIRONMENTAL REVIEW lssuance of an amendment to Certificate of Compliance GDP-1 to revise TSR 2.4.4.12 on the cascade cell trip function is subject to the categorical exclusion provided in 10 CFR 51.22(c)(19). Therefore, neither an environmental assessment nor an environmental impact statement is required for the proposed action.
CONCLUSION The proposed revision to the TSR provides clarification on restoring battery parameters and entering different modes while in Condition E. Those changes are consistent with the staff's understanding of the intent of the TSR and are acceptable. USEC has also proposed an alternative tast for the functional check on manual ce!! shutdown. This test can be used to test those cells that were shutdown at the time of transition and could not be started because of the lack of surveillance. The alternative test provides an acceptable means of conducting the functional test. The staff recommends that the TSR changes be approved.
The staff is not approving the changes to SAR page 4.312 concerning the surveillance test frequency.
The Region til inspection staff have no objection to this proposed action.
Princloal Contributor Merri Horn DISTR BUTION: (Control No. 23oS)
Docket 70 70o1 NRC File Center PUBLIC Rlli KO'Brien, Rill NMSS rif NMSS dir ofc. r/f FCSS rIf FCOB SPB r/f PHiland, Rill OFC SPB C fSPB h SPB. [ SPB ,[
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