ML20246F398
| ML20246F398 | |
| Person / Time | |
|---|---|
| Site: | Limerick  |
| Issue date: | 06/30/1989 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20246F384 | List: |
| References | |
| NUDOCS 8907130239 | |
| Download: ML20246F398 (7) | |
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- UNITED STATES
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CASHWGTON, D. C. 20556
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SAFETY. EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO. 30 TO FACILITY OPERATING LICENSE NO. NPF-39 AND SUPPORTING SINGLE LOOP OPERATION OF LIMERICK, UNIT 2 PHILADELPHIA ELECTRIC COMPANY LIMERICK GENERATING STATION. UNITS 1 AND 2 DOCKET NOS. 50'-352/353
1.0 INTRODUCTION
By letter dated November 4,1988, (Ref.' 1) Philadelphia Electric Company
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(the licensee or PECo) requested an amendment to Facilit No. NPF-39 for the Limerick Generating Station, Unit 1 (y Operating License LI).
The proposed amendment would revise the Technical Specifications (TSs) to permit operation of the reactor with one of two reactor recirculation loops in service.under certain specified conditions.
Included with the application was a report analyzing Single Recirculation Loop Operation (SLO) for extended periods of time for LI prepared by General Electric Company (GE) (Ref. 2).
Construction of Limerick, Unit 2 (L2) has been completed. On June 22, 1989, the Commission issued Facility Operating License NPF-83, together with TSs, authorizing fuel loading and precriticality testing of L2. To support SLO of L2 following licensing, PEco submitted by letter dated Narch 29, 1989 an analysis for L2 and a report prepared by GE (Refs 3 and
.4) similar to those submitted for L1. The TSs which were issued with the fuel load license for L2 do not contain the' changes and additions being approved by this amendment for L1, since the amendment had not been approved at the time of licensing. The TSs which we expect to issue with any future license for L2 authorizing low power or full power operation will include changes and additions parallel to those approved herein for L1. Limerick, Units I and 2 are identical BWR4 reactors. The SLO analyses and results are the same for both reactors, and this evaluation, conclu-sions and TSs approval apply eoually to both reactors.
In addition to the proposed changes to the TSs for SLO, PEco has also proposed several admin-1strative TSs changes which are a necessary condition to approval of SLO to resolve potential concerns related to thermal hydraulic stability in this mode of operation.
Current Limerick TSs require shutdown of the reactor within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> when only one recirculation loop is in operation. Proposals for TS changes to allow extended operating time under SLO conditions have been accepted in recent year:: for a large number of BWRs with similar restrictions. A previously existing primary problem area for SLO relating to thermal hydraulic stability (THS) concerns, has been largely resolved for SLO.
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&$N' y This has occurred by the introduction of TS requiring avoidrnce of potentially unstable regions of the power flow map and surveillance in neighboring regions, and more recently by interim operating procedures requirements described in NRC Bulletin No. 88,07 and Supplement I to that bulletin (Ref. 5).
NRC Generic Letters 86-02 and 86-09 (Refs. 11 and 12) present staf f positions in the areas of SLO and related THS surveillance requirements.
In addition to the THS changes, it is necessary to reexamine the analyses of. abnormal operational transient and accident events under SLO' conditions-and provide for required changes, including TS changes, of trip setpoints and operating and safety limits resulting from the changed reactor 1
conditions. The necessary analyses are provided in the GE reports (Refs. 2 and 4).. and PEC0 has proposed the necessary changes to the TS.
These analyses and changes are similar to those approved in previous reviews of SLO operations.
The March 29, 1989 submittal provided additional analyses to support the proposed TS changes and did not alter the action notir.ed in the Federal Register on March 8, 1989 or affect the intMded no significant hazards determination.
2.0 EVALUATION GE has provided (Refs. 2 and 3) the results of the reexamination, and where required, reanalysis of transients and accidents relevant to SLO.
The events examined are the same as those considered and approved in previous staff reviews of SLO. These include the abnormal operational transients involving flow increase, flow decrease, cold water injection, pressurization and rod withdrawal events. Events requiring analysis have bcen analyzed with standard, staff approved method 7hgy as described in GESTAR II (Ref. 6). For SLO these events begin at a maximum power level about 30 percent less than that for two loop operation (TLO). Thus maximum transient conditions are for the most part less severe than those analyzed for TLO. AveragePowerRangeMonitor(APRM)andRodBlock Monitor (RBM)tripsetpointequationsrequireadjustmentforthese analyses and for operations under SLO conditions to account for the changes in actual core flow versus measured flow as a result of backflow in idle jet pumps. These changes in trio equations in turn require TS changes for SLO.
As is normally the case, the reexamination of these transient events by GE resulted in substantial margin to safety limits. The operating limit minimum critical power ratio (MCPR) remains unchanged as determined by TLO. These results are expected and acceptable.
The safety limit MCPR does change, however. Two of the uncertainties involved in the determination of this safety limit are increased by SLO.
These are (1) the random noise for the neutron flux detector readings (called the TIP readings) used for power determination, and (2) core flow I
measurement uncertainty. The analyses for these increased uncertainties are the same as have been presented and accepted in previous SLO reviews.
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... The result is an increase of 0.01 in the safety limit MCPR. This is a reasonable and acceptable change.
The only accident event, other than LOCA, relevant to SLO is the recirculation pump seizure accident.
It was not specifically reanalyzed for Limerick. However, previous reviews for a range of reactors (including a large BWR4) requesting SLO (e.g., Refs. 7, 8 and 9) have provided analyses, approved by the staff, that have shown that the event results in a MCPR significantly above the SLO safety limit.
It is concluded that this result is also applicable to Limerick.
SLO affects LOCA calculations primarily by decreasing core flow more rapidly than for TLO and thus decreasing the time to departure from nucleate boiling. To examine this and other effects of SLO, LOCA analyses were performed using standard, approved methodology and covering a full spectrum of large break sizes. These analyses result in a required reduction factor of 0.89 for L1 and 2 current fuel assembly maximum average planar linear heat generation rate (MAPLHGR) limits. With this limit reduction factor the large ane: small break LOCA results remain within required limits.
This type of analysis and the reduction factor (of similar magnitude) have been reviewed and approved in previous SLO reviews and is acceptable for L1 ard 2.
In addition to relevant transients and accidents, GE has examined several other areas possibly associated with SLO. These include containment analysis, ATWS, fuel mechanical performance and pressure vessel internal vibrations.
As in previous SLO reviers, because of the more limited power flow region of SLO, the reactor conditions associated with these areas for Limerick SLO generally fall within previously analyzed TLO bc.nds, with results within required limits. However, to assure conservatism, and in keeping with previous SLO submittals and approvals, there are proposed TS requiring (1) limitations on power (70 percent of rated) and flow (one pump speed 90 percent of rated), (2) additional surveillance on recirculation loop differential temperature to prevent stratification and associated stresses, (3) surveillance for the jet pumps to asa re that increased vibration does not adversely affect jet pump performance, and (4) manual flow control to prevent possible control oscillations. These are measures approved in previous SLO reviews and are acceptable for L1 and 2.
It is required for approval of SLO that TS providing for suitable surveillance fo/ monitoring THS be in place.
L1 already has TS providing for surveillance related to THS concerns for TLO. PECO has now proposed that these specifications be modified to apply to SLO. There are proposed ck nges to details of these specifications to insert SLO requirements and to improve the clarity of the specifications and the surveillance regions.
These revised TS are similar to others approved for SLO and are acceptable for Limerick.
In addition to the THS TS, PECO has responded (Ref. 10) to l
NRC Bulletin 88-07 and to Supplement I to that bulletin which requests action with regard to utility operator training and procedure improvement following the LaSalle instability event and subsequent GE interim recommendations (also adopted by the BWR Owners Group) for operations
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related to THS.. These responses indicate that L1 and 2 are (or will be) in full compliance with the NRC request to improve training and implement the GE operating recommendations.
It is not necessary to alter the TS to
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implement the recommendations. The THS TS may be changed in the future when final solutions for THS concerns are approved by the NRC.
3.0 TECHNICAL SPECIFICATIONS PECO has proposed that the following TS be changed to provide for SLO requirements. For the most part the reasons for these changes have already been discussed and staff approval indicated. These changes are appifcable to both L1 and 2.
There are several administrative changes included to provide clarification of language or intention.
Specification 2.1.2. - The safety limit MCPR is changed to 1.08 for SLO.
It remains at 1.07 for TLO. This increase of 0.01 because of increased power and flow noise and uncertainty, as previously discussed, is acceptable.
Table 2.2.1-1. - The APRM trip setpoint change for SLO is added. This change to account for the difference in measured and actual core flow, as previously discussed, is acceptable. No high flow clamp is required since such flow levels are not attainable.
Specification 3.2.1. - The reduction of 0.89 for the SLO MAPLHGRs is provided. As previously discussed, this is acceptable.
Specification 3.2.2. - This also changes the APRM trip setpoint equation for SLO as in Tabfe 2.2.1-1 and is acceptable.
Ficures 3.2.3-la, b, e and d. - These are administrative changes adding a ii~ote to indicate that the figures apply to both SLO and TLO. They are acceptable.
(Figures 3.2.3-Ic and 3.2.3-Id were added to the TSs by Amendment No. 19 issued April 24, 1989. These figures did not exist at the time of the licensee's application. The figures all relate to MCPR limits and all were revised by Amendment 19 which imposed revised limits for the Cycle 3 reload. The note advises the reader that the curves are applicable for both dual and single recirculation loop operation. The addition is administrative and has no safety significance since it does not change anything.)
Table 3.3.6-2. - Along with the scram trip setpoints the rod block type setpoints are changed for both the APRM and RBM to add SLO trips. They are acceptable. This includes the note referring to TS 3.2.2.
Specification 3.4.1.1. - This specification receives a number of additions and changes to account for the majority of requirements for SLO. These include, in the Action section, requirements for flow control in Local Manual mode, pawer level not above 70 percent, MAPLHGR limit reduced by 0.89, pump speed not above 90 percent, differential temperature
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surveillance for power not above 30 percent or for recirculation flow above 50 percent, and reduction of APRM and RBM trip setpoints. These action items have been previously discussed and are acceptable. The associated action times are similar to those previously reviewed and approved for SLO and are reasonable and appropriate for L1 and 2.
There are also additions and changes to the Action and Surveillance sections requiring THS surveillance when operating in restricted regions of the power-flow map. The regions are better defined (with a new Figure 3.4.1.1-1) and SLO requirements added. These changes have been previously discussed and are acceptable. There are also additions to the Surveillance section, adding 4.4.1.1.4 and 5 (and footnote) which provide for surveillan o requirements for the above actions for SLO. The required surveillance and frequencies are reasonable, generally in accord with previous reviews and acceptable.
Specification 3.4.1.2. - The jet pomp specification has been changed to provide for surveillance in SLO conditions. The SLO surveillance is similar to that for TLO in terms of deviations from normal established (in startup measurements) characteristics. This is acceptable.
Specification 3.4.1.3. - There is an administrative change Ifmiting applicability (recirculation loop mismatch) to TLO and indicating that, if one loop is shutdown because of a mismatch, the Action of TS 3.4.1.1 should l
be followed. This is acceptable.
There are minor changes to Bases 2.0,3/4.1.3,3/4.2.1 through'.3 and 3/4.4.1 addressing the above TS changes. They suitably ref'2ct the TS changes and are acceptable.
4.0
SUMMARY
We have reviewed the repcets submitted by PECO for L1 and 2 proposing TS changes relating to SLO and THS. Based on this review we conclude that appropriate documentation was submitted and that the proposed changes satisfy staff positions and requirements in these areas. Extended SLO operation and THS monitoring in the manner thus descrfoed, and as augmented by compliance with the requests of NRC Bulletin 88-07 and Supplement 1, are acceptable.
5.0 ENVIRONMENTAL CONSIDERATION
This amendment involves a change to a requirement with respect to the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and changes to the surveillance requirements.
The staff has cetermined that the amendment involves no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has previously issued a proposed finding that this amendment involves no significant hazards consideration and there has
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I been no public coment on such finding. Accordingly, this amendment meets I
the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9). Pursuant to 10 CFR 51.22(b), no environmental impact statement nor environmental assessment need be prepared in connection with the issuance of this amendment.
6.0 CONCLUSION
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The Comission made a proposed determination that the amendment involves no significant hazards consideration which was published in the Federal Register (54 FR 9919) on March 8, 1989 and consulted with the State of Pennsylvania. No public comments were received and the State of Pennsylvania did not have any coments.
The staff has concluded, based on the considerations discussed above, that:
(1) there is reasonable assurance that the health and safety of the ublic will not be endangered by operation in the proposed manner, and p(2) such activities will be conducted in compliance with the Comission's regulations and the issuance of this amendment will not be inimical to the coisnon defense and the security nor to the health and safety of the public.
Principal Contributor: Howard Richings Dated:
June 30, 1989 l
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REFERENCES 1.
Letter and enclosures from E. Bradley, PECO, to T. Murley, NRR, dated November 4,1988, " Limerick Generating Station, Unit 1."
2.
CE report NEDC-31300-P, " Single Loop Operation Analysis for Limerick 1 "
i October 1988.
3.
Letter from J. Kemper, PECO, to NRC, dated March 29, 1989, " Limerick, Unit 2 Single Loop Operation Analyses."
4.
GE report HEDC-31629-P. " Single Loop Operation Analysis for Limerick 2,"
September 1988.
5.
NRC Bulletin No. 88-07:
Power Oscillations in Boiling Water Reactors (8WRs), June 15, 1988 and NRC Bulletin No. 88-07, Supplement 1, December 30, 1988.
6.
GE report GESTAR II, NEDE-24011-P, Revision 9, dated November 3, 1988.
7.
Letter from R. W. Capstick, Vermont Yarkee, to V. L. Rooney, NRC dated May 9, 1986,
Subject:
Single Loop Operation and Thermal-Hydra::lic Stability: Clarification of PNposed Technical Specification Change No.
132.
8.
Letter from D. Muslof, NSP, to Director of NRR, dated March 24, 1986,
" Request for Amendment to Operating License No. DPR-22."
9.
Letter from T. Riley, Clinton Power Station, dated December 15, 1986,
" Pump Seizure During Single Loop Operation," L3D-86(12-15)-6.
- 10. Letters and enclosures from J. Gallager to NRC, dated September 5, 1988 and March 7, 1989, "NRC Bulletin No. 88-07" and " Response to NRC Bulletin No. 88-07, Suppleoent 1."
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- 11. Generic Letter No. 86-02, " Technical Resolution of Generic Issue l
B-19-Thermal Hydraulic Stability," January 23, 1986.
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- 12. Generic Letter No. 86-09, " Technical Resolution of Generic Issue No.
B-59-(N-1) Loop Operation in BWRs and PWRs," March 31, 1986.
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