ML20132B873
| ML20132B873 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 03/21/1984 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20132B871 | List: |
| References | |
| NUDOCS 8404110214 | |
| Download: ML20132B873 (8) | |
Text
. . _ _ _ . _ . _ . _ _ _ _ _ . _ . _ _ _ _ _ _ _ _ _ _ _ _ . _ _ . _ _ . _ _ , _ _ . _ . _ _ . . _
- - gresg% UNITED STATES 8
o NUCLEAR REGULATORY COMMISSION 4 g j WASHINGTON, D. C. 20555 '
- * * * * ,o$
l,
- SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION CALVERT CLIFFS UNITS 1 AND 2 DOCKET NOS. 50-317 AND 50-318 SEISMIC OVALIFICATION OF THE 1
AUXILIARY FEEDWATER SYSTEM i
- Introduction Since the accident at Three Mile Island Unit 2, attention has been focused on
, the ability of pressurized water reactors to provide reliable decay heat removal.
While it'is recognized that alternate methods may be available to remove decay heat following transients or accidents, heat removal via the steam generators is the first choice for accomplishing a safe shutdown of the plant. Therefore, i
there should be reasonable assurance that the auxiliary feedwater system (AFW) '
- can withstand the postulated Safe Shutdown Earthquake (SSE), consistent with ,
i other safety-related systems in the plant. i To address this concern, the NRC-developed and initiated Multiplant Action l C-14, " Seismic Qualification of Auxiliary Feedwater Systems." The objective s of this plan is to increase, to the extent practicable,- the' capability of p those plants without seismically qualified AFW to withstand earthquakes up ,
to the SSE level. This program was implemented with the issuance of NRC i
Generic Letter 81-14, dated February 10, 1981. Our review of the licensee's responses to this letter is the subject of this evaluation.
f Evaluation i The enclosed report dated iluly 8,1982 was prepared for us by our consultant, '
. Lawrence Livermore National Laboratory, as part of our technical assistance 1
contract program. The report provides their technical evaluation of the licensee's conformance to the requirements of Generic Letter 81-14 '
In his Technical Evaluation Report, the consultant concludes that the AFW
! system is seismically qualified for the SSE, with one exception. The licensee
. has stated that virtually all manual AFW valves were purchased without any i.
seismic qualification. Based upon subsequent information submitted by letter dated March 14, 1984, we conclude that these valves have been properly qualified !
!- for the SSE.
l Conclusion I ' Based upon our review of the consultant's technical-evaluation, and subsequent information submitted by letter dated March 14, 1984, we concluc'e that the AFW systen has the capability to withstand a safe shutdown earthquake and perfom its essential safety function.
Attachment:
- LLNL . Technical Evaluation -
j Report -
. - . . . _ _m~ .. _m _ _ ~ - - , , - ~ - ~ - . . .
~ ~ " ~
~~
~ R:visid' July'8,1982 i: .
TECl+1ICAL EVALUATION REPORT CALVERT CLIFFS NUCLEAR PLANT UNITS 1 AND 2 _.
SEISMIC QUALIFICATION OF AUXILIARY FEEDWATER SYSTEM
- 1. INTRODUCTION Since the accident at Three Mile Island, considerable attention has been' focused on the capability of nuclear power plants to reliably remove decay h:at. The NRC has recently undertaken.Multiplant Action Plan C-14'" Seismic Qualificacion of AFW Systems" [Ref..1), which is the subject of this i cvaluation.
To implement the first phase of Action Plan C-14, the NRC issued Generic ,
Letter No. 81-14 " Seismic Qualificaton of AFW Systems" [Ref. 2], dated
, February 10, 1981, to all operating PWR licensees. This letter requested each licensee (1) to conduct a walk-down of non-seismically qualified portions of th] AFW system and~ identify oeficienci,es amenable to simple actions to improve seismic resistance, and (2) to provide design information regarding the l saismic capability of the AFW system to facilitate NRC backfit decisions.
l The licensee of Calvert Cliffs Units 1 and 2 responded with a letter dated June 30, 1981 (Ref. 33. The licensee's response was found not to be completc and a Request for Additional Information was issued by the NRC, dated January 6, 1982 (Ref. 4). The licensee provided a supplemental response in a letter
! d:ted February 25,1982 [Ref. 5].
l This report provides a. technical evaluation of the information provided in f the licensee's responses to the Generic Letter, and. includes a recommendation i
( rtgarding the need for aoditional analysis and/or upgrading modification of
. this plant's AFW system.
i .
l l
Lm
.. l l
- 2. EV'ALUATION Information provided in licensee's responses included:
o Specification of the overall seismic capability of the AFW system.
o Identification of AFW system components that are currently non-seismically qualified for SSE.
o Discussion of levels of seismic capability of non-seismically qualified components.
o Description of the AFW system boundary.
o- Status of compliance with seismic related NRC Bulletins ano Information Notices.
! o Results of walk-down of non-seismically qualified areas.
- o Additionally, schematic sketch of th'e AFW system.
o Additionally, identification of areas of modification / upgrade that have recently been completed, and proposed areas and schedules for modifications / upgrade under the long term general AFW system modification.
o , Adoitionally, description of methodologi'es and acceptance criteria for seismicall:t qualified components.
We have reviewed the. licencoe's responses, and a point-to-point evaluation of licensee's responses against Generic Letter's requirements is provided b: low. '
(1) Seismic Capability of AFW System Except for those items identified in the following, the AFW system has been designed, constructed, and maintained to withstand an SSE utilizingmethodsandacceptancedriteriaconsistentwiththatapplicable to other safety-related systems in the plant. Presently those items idenfitied'by the licensee as not being fully qualified seismically are evaluated below:
l 0 Pumps / Motors - Pump turbine and associated trip / throttle valve 1
assembly. However, the licensee has stated that the same model in
(-
another nuclear plant having the similar configuration was qualified for seismic load exceeding that required for Calvert Cliffs Plant.
Therefore, we believe that the turbine and associated trip / throttle
! valve assembly possess seismic capability that will survive an SSE.
, , , - - - -r-
p' Piping - (a) A portion of the AFW pump minimum flow rrcirculation piping. The recirculation line is routed through the non-seismic Class I turbine building, but the minimum flow requi:ement is not.an important safety. parameter with respect to other one-time system functions under emergency conditions and failure of this portion downstream of the first restraction orifice will not significantly j
affect the AFW system function. (b) The 10" exhaust line from each j AFW pump turbine. It is routed through the seismic Class I AFW pump 4 room ano the non-seismic Class I turbine building. However, we considereo it to be acceptable because the turbine building portion of the line is properly supported, and Decause failure or rupture of the line would not significantly affect the AFW' pump turbine i operation. (c) The chemical addition piping which ties into the
, common pump suction piping in the AFW pump room. The line is i
non-seismic Class I and the chemical addition equipment is located in the turbine building. However, this line can be isolated from the AFW system by an existing manual valve located in the pump room. The licensee noted that the portion of piping between the valve and the AFW system is very sniall (two welds). The licensee also plans to cut and cap the additional chemical addition line installed by each AFW containment penetration room of Unit 1 bec6use these lines are not i presently in use.
c Valves / Actuators - All manual valves except for the penetration and
! condensate storage tank No. 12 discharge valves. These manual valves were purchased without seismic qualification, and were installed in seismic lines and analyzed with the system. The licensee noted that-these valves are similar in material and construction to others that I
have been se'ismically qualified. In the absence of any information on the specific level of seismic capability of the other seismically qualified valves, we believe the valves at Calvett Cliffs plants l probably possess a seismic capability that will survive an operating basis earthquake (OBE).
o Power Supplies - All circuit-carrying conduits. They were installed according to standard seismic installation details and guidelines, ,
and will be upgraded to Class lE ouring the general AFW system modifications.
. . . _ - ._ _ ,_, . _ , . . _ , ~ _ _ _ _ ~ _ , _ _ _ _ , _ _ . . . . _
o Water Source (s) - None o Initiation / Control Systems - (a) The Burbon tube type pressure indicators and the remote turbine trip hand-switches. They are being upgraded under the general AFW modification and will meet IE 79-01B and NUREG-0588 intent. (b) The instrument air source for AFW pump turbine throttle. However, it is not a safety related item and when it fails, the throttle valve will be in a fully open position.
o Structures - The turbine building. However, this does not present seismic related concerns because the turbine building houses and supports only components such as the recirculation line, exhaust piping, and chemical addition line, which are not essential to safety
. functon of the AFW system.
Based on our evaluation' described above, those areas of the AFW system judged not to possess an SSE seismic capability are identified below.
O Pumps / Motors None a ' Pipina None o Valves / Actuators OBE o Power Supplies None o Water Source (s) None o Initiation / Control Systems None o Structures None In summary, our evaluation indicates that the licensee's AFW system does not possess an overall seismic capability that can, survive an SSE.
Because the primary water source and supply path is . seismically qualified, switchover to a secondary water source is not involved.
Seismic qualification information for any alternate decay heat removal system was not provided in the licensee's responses. This information was requested by GL 81-14 if substantial lack of seismic qualification is indicated for the AFW system. The licensee stated that its AFW system exhibit a high degree of inherent seismic resistance.
Based on the information providea by the licensee we' did not find that the licensee's AFW system has an.SSE capability. For the purpose'of removing i a m. .w
l
- l. .,
1-decay heat following an SSE, the licensee needs to either re-analyze and/or modify its AFW system or provide an alternate decay heat removal system seismically qualified to the SSE level and appropriate operating
- procedures.
l j Regarding the AFW system boundary, the licensee identified that:
(1) the pump turbine exhaust piping has no isolation valves, but we do not consider the turbine exhaust piping to be part of the boundardy of the AFW system. (2) the recirculation piping has two valves' that are required to l be open during operation of the AFW pumps and cannot be nczmally or
! automatically shut. The recirculation line, however, is seismically 4 mounted to a point downstream of the flow restriction orifices. Should 5
the pipe breaks off downstream of these orifices, no problems would result .
! because the increase in flow through the line would be minimal compared
! with that available to the pump suction. Therefore, we oetermine that the
- AFW system boundary conforms to that required by the Generic Letter.
l The licensee stated that the AFW system was included within the scope i of seismic related Bulletins 79-02, 79-04, 79-07, 79-14, 80-11, and IE '
j (2) Walk-Down of Non-Seismically Qualified Portions.of AFW System i The licensee performed a walk-down of the as-built configurations of j those non-seismically qualified items for which there are no plans to upgrade. Areas where a walk-down was not oe'rformed include the ,
l recirculation piping, pump turbine exhaust piping, all non-seismically qualified manual valves, and instrument air source. We concluoe that the ,
- walk-down performed by the licensee is not , complete. l l (3) Additional Information
! The licensee provided a schematic sketen of the AFW system including the water source, heat sink, suction and discharge piping,reajor meenanical equipment, and structures nousing and supporting AFW system l
items.
l Additionally, licensee's responses provided a description of the i j methcdologies, loading combinations, and acceptance criteria that were i used in the design of the seismic Class I comoonents of the AFW system.
l
- l. .
4
..- , , . - , , - , .,,,,,r... e- .- e < , r .n--~ . . -o , ,- we--r-- -- n --r.,-v.,.~,,,.,-,...w-_--,m -.e-, ,s--n--,,-.en-enn, e,,-e.,ev---v , .m-,e-
The licensee also provided the following information on completed and scheculed modification / upgrade related to, but not as a direct result of, GL 81-14:
o All electric power supplies have been upgraced to Class IE during recent plant modifications.
o Eacn AFW system has been modified to include a safety-related automatic start system in accordance with NUREG 0578 and 0737.
o The general AFW systm modifications are scheduled to be completed by fall 1982 for Unit 2 and fall 1983 for Unit 1. For Unit 2, however,
- the completion date will be delayed to the spring, 1984 outage if equipment deliveries are not met. These modifications include upgrading the pump turbine and associated trip / throttle valve
- assembly, upgrading the chemical addition line to seismic Category 1, cutting and capping the chemical addition lines installed by the Unit 1, containment penetration rooms, and upgrading all circuit carrying' conduits.and initiaticn/ controls to Class IE to meet requirements of
' IE 79-01B and NUREG 0588.
O- The upgraded chemical addition line seismic supports will be installed by January 1, 1983.
- 3. CONCLUSIONS The information containec in licensee's responses to GL 81-14 is complete. The licensee conducted a partial walk-down in that it encompassed only those non-seismically qualified areas which the licensee has no plan to upgrade. The walk-down did not find seismic related deficiencies. Based on ,
submitted information, we concluce that the AFW system does not provide a reasonable assurance to perform its required safety function following an SSE,
! ,'because the non-seismically qualified valves are judged to have only an OBE lovel resistance. Since the licensee does not presently plan to upgrade these
!. valves, we recommend that the NRC considers requiring the licensee to provide a re-analysis and/or modification to acquire an SSE capacity for these valves.
l l
.,, REFERENCES 4
- l. D. G. Eisenhut, U.S. Nuclear Regulatory Commission, memorandum to H. R. ,
l Denton, "Multiplant Action Plant C-14: Seismic Qualification of Auxiliary !
Feedwater Systems," February 20, 1981.
- 2. U.S. Nuclear Regulatory Commission, Generic Letter No. 81-14 to all operating pressuri.ted water reactor licensees, " Seismic Qualification of Auxiliary Feedwater Systems," February 10, 1981.
~
- 3. A. E. Lunavall, Jr., Baltimore Gas & Electfic, letter to R. A. Clark of U.S. Nuclear Regulatory Commission, June 30, 1981.
4 R. A. Clark, U.S. Nuclear Regulatory Commission, letter to A. E. Lundvall i
of Baltimore Gas & Electric, " Request for Adoitional Information on Seismic Qualification of the Auxiliary Feedwater System, Calvert Cliffs Nuclear Plants Units 1 and 2," January 6,1982.
9
- 5. A. E. Lundvall, Jr., Baltimore Gas & Electric, letter to R. A. Clark of U.S. Nuclear Regulatory Commission, February 25, 1982.
O c
l .
. . . . _