ML20057B609
| ML20057B609 | |
| Person / Time | |
|---|---|
| Site: | Maine Yankee |
| Issue date: | 09/17/1993 |
| From: | Trottier E Office of Nuclear Reactor Regulation |
| To: | Frizzle C Maine Yankee |
| References | |
| REF-GTECI-A-46, REF-GTECI-SC, TASK-A-46, TASK-OR TAC-M76659, NUDOCS 9309220332 | |
| Download: ML20057B609 (7) | |
Text
_.
September 17, 1993 Docket No. 50-309 Mr. Charles D. Frizzle, President Maine Yankee Atomic Power Company 83 Edison Drive Augusta, Maine 04336
Dear Mr. Frizzle:
SUBJECT:
REVIEW 0F MAINE YANKEE RESPONSE TO NRC COMPARIS0N BETWEEN SEISMIC.
MARGIN ASSESSMENT AND USI A-46 SEISMIC VERIFICATION (TAC NO. M76659)
In our letter dated April 29, 1993, we provided the results of a comparison between the Maine Yankee Seismic Design Margin Program and Unresolved Safety i
Issue A-46, Seismic Qualification of Equipment in Operating Plants. The staff i
has reviewed your letter of response dated June 15, 1993.
Of the nine issues identified in the comparison, the staff finds issues I, 2, 5 and 6 to be of unlikely safety significance and considers them resolved.
The documentation you provided of.a previous seismic evaluation of equipment modifications and replacement is adequate to resolve issue 4.
Four issues (3, 7, 8, and 9) remain.
Issues 7 and 8 (Loss of Offsite Power j
and Long Term Heat Removal, respectively) were not fully addressed in your letter.
Issues 3 and 9 (Omission of Relay and Breaker Chatter, and Seismic Fragility / Capacity Estimates and Walkdown, respectively) remain unresolved.
Our evaluation of your response is enclosed. We request that you provide the information necessary to fully address and therefore resolve the four l
remaining issues identified above, within sixty days of receipt of this letter.
l l
Should you have any questions on this matter, please' do not hesitate to l
contact me.
Sincerely, 1
Original signed by E. H. Trottier, Project Manager Project Directorate I-3 Division of Reactor Projects - I/II i
Office of Nuclear Reactor Regulation
Enclosure:
Evaluation of Response to Seismic Comparison l
l cc w/ enclosure:
See next page LA:PRI;G),
PM:PDI[
D:PDI-3 / b OFFICE NAME SLi M ETr k k aw WButler
' DATE 9 /M/93 OC) W /93 k /g '793
//
/ /
OFFICIAL RECORD COPY
{
FILENAME: A:\\MYM76659.LTR 788'*!888R !!88 L NRC FILE CENTER COPY Ol P
PDR f
pR MC fY 4
UNITED STATES e,
[
W j
NUCLEAR REGULATORY COMMISSION
~f WASHINGTON, D.C. 20556-0001 l
/
September 17, 1993
+....
Docket No. 50-309 Mr. Charles D. Frizzle, President Maine Yankee Atomic Power Company 83 Edison Drive Augusta, Maine 04336
Dear Mr. Frizzle:
SUBJECT:
REVIEW 0F MAINE YANKEE RESPONSE TO NRC COMPARIS0N BETWEEN SEISMIC MARGIN ASSESSMENT AND USI A-46 SEISMIC VERIFICATION (TAC NO. M76659)
In our letter dated April 29, 1993, we provided the results of a comparison i
between the Maine Yankee Seismic Design Margin Program and Unresolved Safety Issue A-46, Seismic Qualification of Equipment in Operating Plants. The staff has reviewed your letter of response dated June 15, 1993.
Of the nine issues identified in the comparison, the staff finds issues 1, 2, 5 and 6 to be of unlikely safety significance and considers them resolved.
The documentation you provided of a previous seismic evaluation of equipment modifications and replacement is adequate to resolve issue 4.
Four issues (3, 7, 8, and 9) remain.
Issues 7 and 8 (Loss of Offsite Power and Long Term Heat Removal, respectively) were not fully addressed in your letter.
Issues 3 and 9 (Omission of Relay and Breaker Chatter, and Seismic Fragility / Capacity Estimates and Walkdown, respectively) remain unresolved.
Ger evaluation of your response is enclosed. We request that you provide the iaformation necessary to fully address and therefore resolve the four remaining issues identified above, within sixty days of receipt of this letter.
Should you have any questions on this matter, please do not hesitate to contact me.
j Sinc e E. H. Trottier, Project Manager Project Directorate I-3 Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation
Enclosure:
Evaluation of Response to Seismic Comparison cc w/ enclosure:
See next page
Mr. Charles D. Frizzle Maine Yankee Atomic Power Station CC:
Mr. Charles B. Brinkman Mr. James R. Hebert, Manager Manager - Washington Nuclear Nuclear Engineering and Licensing Operations Maine Yankee Atomic Power Company Combustion Engineering, Inc.
83 Edison Drive 12300 Twinbrook Parkway, Suite 330 Augusta, Maine 04336 Rockville, Maryland 20852 Mr. Robert W. Blackmore Thomas G. Dignan, Jr., Esquire Plant Manager Ropes & Gray Maine Yankee Atomic Power Company One International Place P.O. Box 408 Boston, Massachusetts 02110-2624 Wiscasset, Maine 04578 Mr. Uldis Vanags Mr. G. D. Whittier, Vice President State Nuclear Safety Advisor Licensing and Engineering State Planning Office Maine Yankee Atomic Power Company State House Station #38 83 Edison Drive Augusta, Maine 04333 Augusta, Maine 04336 I
Mr. P. L. Anderson, Project Manager Mr. Patrick J. Dostie Yankee Atomic Electric Company State of Maine Nuclear Safety 580 Main Street Inspector Bolton, Massachusetts 01740-1398 Maine Yankee Atomic Power Company P. O. Box 408 l
Regional Administrator, Region I Wiscasset, Maine 04578 U.S. Nuclear Regulatory Commission 475 Allendale Road Mr. Graham M. Leitch King of Prussia, Pennsylvania 19406 Vice President, Operations Maine Yankee Atomic Power Company First Selectman of Wiscasset P. O. Box 408 Municipal Building Wiscasset, Maine 04578 U.S. Route 1 Wiscasset, Maine 04578 l
Mr. J. T. Yerokun Senior Resident Inspector Maine Yankee Atomic Power Station l
U.S. Nuclear Regulatory Commission P. O. Box E Wiscasset, Maine 04578
.o ENCLOSURE NRC EVALUATION OF THE MAINE YANKEE RESPONSE DATED JUNE 15, 1993, T0 l
ISSUES RAISED IN THE NRC LETTER DATED APRIL 29, 1993, REGARDING THE COMPARISON BETWEEN THE SEISMIC MARGIN ASSESSMENT.(SMA) AT MAINE YANKEE AND USI A-46 PROVISIONS Issues 1. 2. 5. and 6 The staff considered these issues unlikely to be of safety significance and, therefore, considers them resolved.
Issue 3. Omission of Relav and Breaker Chatter In its response to this issue, MYAPCo indicated that it now has four engineers formally trained in the SQUG relay review methods (EPRI NP-7148) and is planning to conduct the relay reviews with the remaining tasks to fulfill its commitment for completion of the IPE/EE by mid-1995. However, MYAPCo's response was not specific with regard to the procedure that will be used for performing the relay seismic review, and the earthquake level that will constitute the basis for the seismic demand. As stated in its correspondence dated April 29, 1993, the staff considers the licensee's commitment to use SQUG GIP, Revision 2, for performing the USI A-46 relay seismic adequacy reviews utilizing an earthquake level consistent with the NUREG/CR-0098 50th percentile spectrum anchored at 0.189, an adequate basis for resolving this issue.
However, if MYAPCo does not intend to make such a commitment, it should clearly identify, for staff evaluation, the criteria and procedures that will be used in performing the relay seismic adequacy review.
Issue 4. Eautoment Modifications and Reolacement The staff considers this issue resolved.
Issue 7. Loss of Offsite Power (LOOP)
In response to this issue, MYAPCo focused on the potential for certain additional spurious actuation of relays if offsite power were to remain available. However, as stated in the staff's correspondence of April 29, 1993, there is additional equipment available during shutdown whose failure during an earthquake could impact essential equipment in the safe shutdown path.
Some of the additional equipment was not examined as part of the Maine Yankee SMA, because the LOOP was assumed to occur. Therefore, to fully resolve this issue, the seismic adequacy of this sub-set of equipment, in the safe shutdown path, should be established considering the possibility of not losing offsite power.
Issue 8. Lona-Term Heat Removal MYAPCo stated that an additional 100,000 gallons of water from the l
seismically-qualified Condensate Storage Tank (CST), not considered in the SMA and NRC study, is available. According to the NRC's simplified calculations (which the licensee agreed with, "with small differences"),
i
-a
(
2 l
1 l
this additional inventory would still be insufficient (a shortfall of about 100,000 gallons) to meet the 72-hour guideline. MYAPCo further indicated that by utilizing a combination of steaming and feed and l
bleed, a sufficient inventory would be available considering the extra CST volume of 100,000 gallons.
It is not clear to the staff how this combination of core cooling methods, using the available water inventory, could extend the shutdown condition and achieve the 72-hour guideline.
In order to resolve this issue, MYAPCo should (1) demonstrate by calculations the validity of the proposed decay heat removal capability, (2) identify the operating procedures that are in place for removal of decay heat by employing a combination of the proposed core cooling methods, and (3) demonstrate that the seismic adequacy of the CST satisfies the SQUG GIP, Revision 2, provisions for tank evaluation utilizing an A-46 earthquake level (0.18g NUREG/CR-0098 l
spectrum) or equivalent.
The other alternative suggested in the Maine Yankee response is the use of water from the fire system to replenish the Demineralized Water Storage Tank (DWST) using seismically-qualified equipment. The staff agrees that this could be a viable approach. However, it needs to be l
demonstrated by calculations that the fire system can provide the l
necessary demand (both flow rate and total capacity), with loss of offsite power, and that the critical equipment in the fire system is seismically qualified to an A-46 earthquake level (0.18g NUREG/CR-0098 spectrum) or equivalent.
Issue 9. Seismic Fraaility/Canacity Estimates and Walkdown The concern in this issue is not, as stated by Maine Yankee, the tradeoff between the use of nationally-accredited seismic experts to perform plant seismic reviews and the sole use of utility staff engineers.
The issue is whether the undesirable experiences from certain earthquakes and equipment testing (collectively identified as
" caveats" in SQUG GIP, Revision 2, dated February 14,1992) have been properly addressed for equipment installed at Maine Yankee Atomic Power Station (MYAPS).
The GIP developed by SQUG is a final product of the industry, SQUG, and the NRC staff and its consultant's efforts.
The NRC has contributed significantly to the GIP's final criteria and procedure through research and collections of experience data.
Many equipment " caveats" were developed based on these experience data and vendor-supplied information after the Maine Yankee SMA effort was completed and might not have been available to those experts and consulting engineers at the time of the plant-walkdown.
Therefore, we are concerned that all the earthquake and test experience " caveats" may l
not have been assessed for safe shutdown equipment installed at MYAPS.
This is the reason that the staff, in its April 29, 1993, letter, concluded that, as a minimum, a sample walkdown be performed by the staff, of selected equipment, to verify whether, in spite of the differences between these two methods, the Maine Yankee SMA was sufficiently adequate to resolve the USI A-46 issue at MYAPS, or whether additional action is required to satisfy the USI A-46 resolution.
l 3
In its June 15, 1993, letter, MYAPCo stated that the consulting engineers and senior managers (identified in Attachment 4 to the June 15, 1993, letter) who performed the Maine Yankee review and walkdowns literally wrote the book for today's plant seismic review programs, both A-46 and IPE/EE.
It has also stated its belief that the performance of l
t walkdowns using seismic experts without detailed procedures is equivalent to the performance of walkdowns by non-expert engineers with detailed procedures. MYAPCo further stated that performing the review again using procedures written by the same individuals who performed the plant review would not result in a substantial increase in the overall protection of public health and safety.
The staff acknowledges the seismic expertise of the consulting engineers that performed the Maine Yankee SMA review and walkdowns and would accept a confirmatory letter from MYAPC0 as an adequate basis for addressing the seismic fragility / capacity issue at the facility. The letter should confirm that the earthquake and test experience " caveats" (GIP, Revision 2, dated February 14, 1992) have been adequately addressed in the safe shutdown equipment installed at MYAPs and that the equipment in the safe shutdown path is seismically adequate to perform their intended function for an earthquake with the NUREG/CR-0098 50th l
percentile spectrum anchored at 0.18g.
l l
DISTRIBUTION:
Docket File NRC & LocalPDRs PDI-3 Reading SVarga JCalvo j
WButler i
Slittle i
ETrottier i
JLinville, RI I
e s
i l
l r
t