ML20079J149
| ML20079J149 | |
| Person / Time | |
|---|---|
| Site: | Three Mile Island  |
| Issue date: | 01/06/1984 |
| From: | Pollard R, Weiss E HARMON & WEISS, UNION OF CONCERNED SCIENTISTS |
| To: | NRC COMMISSION (OCM) |
| Shared Package | |
| ML20079J135 | List: |
| References | |
| NUDOCS 8401240230 | |
| Download: ML20079J149 (13) | |
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00CKETED USNRC guC g 3'8td:53 UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION -
BEFORE THE COMMISSION In the Vatter of )
)
METROPOLITAN EDIS0N COMPANY ) Docket No. 50-289
) (Restart)
(Three Mile Island Nuclear )
Station, Unit No. 1) )
UCS REBUTTAL TO LICENSEE'S REPLY REGARDlHG EFW FLOW INSTRUMENTATION Introduction On December 6, 1983, counsel for GPU transmitted to the Commission a document which it characterized as "potentially relevant and material to matters under adjudication in the' plant design and procedures phase" of the TMl-1 restart proceeding. The document is a letter from H. D. Hukill, Director of TMI-1, to J. F. Stolz, NRC Staff, dated November 23, 1983. The letter disclosed that the emergency feedwater (EFW) flow instruments installed
- at THI-1 to comply with the short-term " lessons learned" requirements do not meet NRC's criteria ~ or GPU's commitment in the res. tart proceeding. On ,
December 9, 1983, UCS filed with the Corrmission, " Union of Concerned Scientists Response to GPU Letter of December 6, 1983, Regarding Emergency Feedwater Flow Instrumentation." (Hereinafter, "UCS Response") On December 23, 1983. GPU filed with the Commission, " Licensee's Reply to UCS Response to GPU Letter of December 6, 1983, Regarding Emergency Feedwater. Flow 8401240230 840120 PDR ADOCK 05000299 9 PDR
Instrumentation." (Hereinafter, . " Licensee's Reply") Licensee's counsel claimed that its reply was submitted "in order to correct the serious factual errors in the UCS pleading, which might otherwise be overlooked because of the extent and exaggerated nature of the misplaced arguments which are built upon them."1 UCS has evaluated Licensee's arguments and submits this rebuttal to.
demonstrate that UCS made no factual errors and that the evidence supports our arguments.
Discussion GPU's first defense is that +10% accuracy is not "a performance criterion which is part of the ' lessons learned' requirement for EFW flow i ns trumenta ti on. "2/ Licensee claims uneouivocally that "there is absolutely no basis for the UCS characterization of +10% accuracy as a 'reouirement' for EFW flow instrumentation."3_/
Perhaps the Licensee has not read all of the pertinent material. In fact, during the THI-1 restart hearing, the requirement for EFW flow indicationwasasfollows:1/
4 POSITION Consistent with satisfying the requirements set forth in GDC 13 i to provide the capability in the control room to ascertain the actual perfonnance of the AFWS when.it is called to perform its intended function, the following requirements shall be implemented: .
1/ Licensee's Reply at 1-2.
2/ Id. at 2. .
3/ Id. at 2-3.
-4/ Staff Ex.1, ?!UREG-0680, "TMI-1 Restart," June 1980, p. Cb-38, emphasis added.
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- 1. Safety-grade indication of auxiliary feedwater flow ~to each steam generator shall be provided in the control room. ,
- 2. The auxiliary feedwater flow instrument channels shall be powered from the emergency buses consistent with satisfying the emergency power diversity reouirements of the auxiliary feedwater system set forth in Auxiliary Systems Branch Technical Position 10-1 of the Standard Review Plan. Section 10.4.9.
CLARIFICATION
- 1. Auxiliary feedwater flow indication to each steam generator shall satisfy the single failure criterion.
- 2. Testability of the auxiliary feedwater flow instrument channels shall be a feature of the design.
- 3. Auxiliary feedwater flow instrument channels shall be powered from the vital instrument buses.
- 4. Auxiliary feedwater flow indication to each steam generator shall satisfy safety-grade reouirements.
- 5. For items 1-3, the flow indication channels should by themselves satisfy the sinole f ailure criterion for each steam generator. As a fall-back position, one auxiliary feedwater flow channel may be backed up by a steam generator level channel .
- 6. Each auxiliary feedwater flow channel should provide an analog indication of feed flow with an accuracy on the order J1! .110%*
Thus, a +10% accuracy criterion was clearly in effect. The NRC Staff testified that the licensee had committed to installing two safety grade sonic flow devices on each of the two EFW supply lines to the steam generators and that the licensee " indicated that the new flow devices have an accuracy of better than +5%, which is acceptable to the staf f."I Based on its review and evaluation of this information, the Staff concluded that TMl-1 was "in compliance with all the requirements of NUREG-0578, i tem 2.1.7.b , subj ect to
-5/
Id., p. C8-39. Actually, the Staff exaggerated Licensee's claim. GPU only said that the EFW flow instruments would have an " accuracy of better than or eaual to 5%." See Lic. Ex. 1, Am. 22, p. 2.1-23.
subrnittal of the . vendor environmental cualification certification."6,/ The Licensing Board relied upon the information provided by GPU and the Staff's conclusion "that Licensee is in compliance with the NUREG-0578 recommendation,
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in item 2.1.7.b, for emeroency feedwater flow indication to the steam generators." I In November 1980, after the licensee and staff testimony on which the t.icensing Board relied was submitted, NUREG-0737 was published. With respect to EFW flow instrumentation. the most pertinent part of HUREG-0737 is the following:EI Clarification The intent of this recommendation is tc assure a reliable indication of AFWS performance. This ob.iective can be met by providing an overall indication system that meets the following appropriate design principles:
(1) For Babcock and Wilcox Plants (a) To satisfy these reauirements, BAW plants must provide as a minimum two auxiliary feedwater flowrate indicators for each steam generator.
(b) The flow indication system should conform to the following salient paraoraphs of IEEE 279-1971:
IEEE 279-1971' PARAGRAPH 4.1" General Functional Reauirements '
4.2* Single Failure l 4.3 & 4.4 Oualification i 4.6 Channel Independence j 4.7 Control and Protection System Interaction i 4.9* & 4.10* Capability for Testing l
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- These requirements were part of the shor.t-term control-grade requirements.
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j 6/ Id., p. C8-40. The Staff subsequently addressed the environmental l qualification of the sonic flow devices. See Staff Ex. 14, NUREG-0680, i Supp. No. 3, April 1981, pp. 38-39.
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.7/ Metropolitan Edison Co., (Three Mile Island Nuclear Station, Unit 1),
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l G>-81-59, 14-NRC 1211, 1362, December 14, 1981.
! 8,/ HUREG-0737 at 3 3-83.
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_.- , - - _ _ _ , _ . _ _ _ . _ , . . _ ~ , ,, , _ . - - - . _ , _ _ ._
-S-In 'ef fect, the earlier " Clarification" itens listed in NUREG-0680 were
. folded into the " Clarification" in NUREG-0737 that the EFW flow instruments should meet the listed portions of IEEE 279-1971. One of the pertinent IEEE 279-1971 sections cited provides as follows:
4.1 General Functional Requirement. The nuclear power generating station protection system shall, with precision and reliability, automatically initiate appropriate protective action whenever a condition monitored by the system reaches a preset level . This requirement applies for the full range of conditions and performance enumerated in Sections 3(7), 3(8),
and 3(9). .
[In turn, Section 3(9) provides as follows:]
- 3. Design Basis A specific protection system design basis shall be provided for each nuclear power generating station. The information thus provided shall be available, as needed, for making judgments on system functional adequacy.
The design basis shall document as a minimum, the following:
(9) minimum performance reauirements including the following:
(a) system response times; (b) system accuracies; (c) ranges (normal, abnormal, and accident conditions) of the magnitudes and rates of change of sensed variables to be accommodated until proper conclusion of the protective action is assured. [ Emphasis added.]
Since the only accuracy figure reported by GPU itself w'as +5% (See n. 5, supra), one could conclude that if NUREG-0737 is applied rather than NUREG-0680. the +51 criterion rather than the +10% criterion is in effect.
. NUREG-0737 surely provides no "out" for GPU. Moreover, in reporting to the NRC Staff six weeks ago, GPU itself stated the following: !
Recent tests performed on the EFW system in conjunction with OTSG. testing indicateo oscillations at low flow conditions (less than approximately 100 gpm) outside the +10% criteria.
-9/ H. 'D. Hukill, Director of TMI-1, to J. F. Stolz, NRC Staf f, "EFW Flow l Devices (D/P) Testing", November 23, 1983, p. 1, emphasis added.
Thus, there seems to have been no ouestion in CPU's mind until very recently that a +10% criterion existed for EFW flow instrumentation accuracy. -
In sumary, CPU's denial that +10% accuracy is a requirement for EFW flow instrumentation is inaccurate.
GPU's second argument is that UCS " ignores the limited flow regime for which the oscilllations occur, and proceeds to postulate the complete absence of EFW flow indication."$/ To begin with, UCS did not postulate " complete absence" of flow indication (whatever that may mean). We postulated "the lack of reliable flow indication."El GPU seems to be arguing that the inability to reliably measure EFW flow at low flow rates is insignificant because "[i]n i
a TMI-2 accident condition, full EFW flow would be desired .
. . . "E It is of course true that full EFW flow would be desired at the outset. However, once the water level in the steam generators reaches the desired level and decay heat diminishes, flow would be throttled to a low flow condition to safely cool the plant down. This is precisely the condition when the EFW flow instruments are said to be inaccurate and the condiMon UCS referrred to when t
we postulated that the lack of reliable flow indication co'uld affect proper operator action.
i In addition, it is worth noting that GPU's November 23, 1983, letter to f the NRC Staff does not precisely indicate for what flow range the instruments i
I are reliable. Mr. Hukill states that testing at flows less than approximately 100 gpn " indicated" that the +10% criterion was not met and that tests l
- l. H / Licensee's Reply at 3.
H / UCS Response at 4.
H/ Licensee's Reply at 3.
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" indicate" that above 400 ppm the _ instruments are within +10%.I3f - gg.also states that "during the Power Escalation testing data will be collected and used to assist the operators in understanding how the EFW flow devices are expected to perform under various ' EFW flow conditions."5 Thus, it appears that it is not known how the instruments will perform under a variety of flow conditions.
GPU's third argument relates to UCS's point that the EFW pumps are cooled by flow through the pumps and that, therefore, " failure of the recirculation flow paths could require prompt operator action to prevent failure of the EFW ,
pumps."5I GPU responded by stating that "UCS apparently is not aware that Licensee has committed to lock open the EFW pump recirculation line valves."5/ GPU is correct that, as of Decenber 9, 1983, UCS was unaware that the recirculation valves are supposed to be locked open. This was subsecuently announced at a NRC Staff /GPU meeting on December 16, 1983.
! However, this does not affect UCS's observation that failure of the recirculation flow paths could reouire prompt operator action because: 1) GPU has demonstrated a proclivity for failing to have valves 'in their correct positions; 2) there are other valves in the' recirculation flow paths which, if closed, could block recirculation flow; and 3) locking open the EFW pump recirculation' line valves creates an additional safety hazard. We explain each of these seriatim.
13/ H. D. Hukill, Director of TMI-1, to J. F. Stolz, NRC Staf f, "EFW Flow
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Devices (D/P) Testing", November 23, 1983, p. 1.
14/ Id. at 2.
M/ UCS Response at 5-6.
16/ Licensee's Reply at 3.
.H.
The adecuacy of the plant design features and administrative controls provided to assure that valves are in their correct positions was a subject of the restart hearing. In response to a contention first advanced by UCS and later adopted as a Licensing Board question, the ASLB found "that the EFW system is important to safety whether or not it was classified as a safety system at the time of the accident." The Board also found that "[t]he existing automatic indicators . . . in conj unction with the additional administrative control being implemented by Licensee . . . will serve to verify the operational readiness of syst- ; important to safety."b Despite these predictions by the Licensing Board, GPU has continued to demonstrate its inability to ensure that important valves are in their correct positions. For example, when containment integrity was reauired, a conflict .
between plant procedures caused a containment isolation valve to be partially open. In another instance, two independent verifications of valve position failed to identify a valve in the " stuck" open position. Finally, the Staff identified "three apparent violations during hot functional testing in which valves were inadvertently left open or were misoperated, that resulted in safetycomponentsbeinginoperableforshortperiodsoftime."N i
Thus, in view of GPU's history of mispositioning valves both prior and subsequent to the TMI-2 accident, GPU's claim that the EFW recirculation line valves will be locked open provides little assurance that recirculation flow will be available. Therefore, the availability of EFW flow instumentation
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17/ Metropolitan Edison Co., (Three Mile Island Nuclear Station, Unit 1),
LBP-81-59, 14 NRC 1211, 1313, December 14, 1981. See also generally paragraphs 887-906 at pp. 1312-1317.
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18/ See Richard W. Starostecki, IE, to H. D. Hukill, Director, THI-1, October 28, 1983, and enclosed Inspection Reports 50-289/83-25 and 50-289/83-26.
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-g-which is accurate at low flows is reouired so that, among other things, prompt operator action might be taken to prevent damage to the EFW pumps if the recirculation flow path is blocked.
Second, UCS is aware from attending NRC Staff /GPU meetings that GPU's promise to lock open the EFW recirculation line valves applies specifically to valves EF-V-8A, EF-V-8B and EF-V-8C. However, the recirculation lines also contain check valves (EF-V-19A, EF-V-19B and FF-V-21) and throttle valves (EF-V20A,EF-V20BandEF-V22).IS/ Even if these valves were added to the list of those which are supposed to be locked open (in the case of the check valves, this might not be possible), the above discussion regarding GPU's history of mispositioning valves would still apply.
Finally, even if all EFW recirculetion line valves were actually locked open, this would create another' safety problem, namely: the loss of excessive water from the condensate storage tank following an earthouake. The recirculation lines are not seismically qualified and have not even been shown to be capable of remaining intact during the very mild Operating Basis Earthouake.E As GPU has noted, the combination of the loss of water from the broken recirculation. l'ines and the CST "B" de-ice line'"would present a safety concern" since there would be not be sufficient water in the Condensate Storage Tanks to cool down the plant.b If the recirculation line valves are locked open, the operator would be unable to close them promptly to halt the water loss. (Of course, since the recirculation line vahves are not presently
,/19Lic. Ex.1, " Restart Report," Figure C-302-081, Rev.17.
20/ H. D. Hukill, Director, THI-1, to Darrell G. Eisenhut, ARC Staff, Seismic Qualification of Auxiliary Feedwater System, September 29, 1981, p. 1.
--21/
H. D. Hukill, Director, TMI-1, to J.- F. Stolz, NRC Staff, July' 7,1982, Encl. 2, " Evaluation'of TMI-1 Condensate Supply for Emergency Feedwater,"
h p. 4.
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seismically cualified either,E! the operator might not be able to close them even if they were not locked open. This is only one aspect of the dilenma CPU faces in trying to justify operation with an EFW system that is not safety grade.)
In summary, locking open the EFW recirculation line valves is not a viable alternative to providing EFW flow indication which is accurate at low flows.
Another argument advanced by GPU in its attempt to justify operation of TMI-1 with inaccurate EFW flow instrumentation is that during manual takeover of the emergency feedwater system, "the operator would not control flow based upon this indication alone. 2_3/ Mr. Hukill also made this point, stating that
" Emergency Feedwater continues to be controlled based on the OTSG level and pressure (level to prevent over/under-filling and pressure to prevent over-cooling). The operator's attention is focuseo on these instruments when regulating flow."El First of all, the requirement for safety grade EFW flow indication was adopted by HRC with full recognition of the existence of steam generator level indication.El However, the utility of steam generator pressure in
-22/ H. D. Hukill, Director, TMI-1, to D. G. Eisenhut. NRC Staff, February 16, 1982, enclosure, Table A.
23/ Licensee's Reply at 4.
-24/ H. D. Hukill, Director of THI-1, to J. F. Stolz, NRC, "EFW Flow Devices (D/P) Testing," November 23, 1983, p. 2.
25/ During the TMl-1 restart hearing, the reouirement for two flow indicators for each steam generator was clarified as follows: "As a fall-back position, one auxiliary feedwater flow channel may be backed up by a.
steam generator level channel." Staff Ex. 1, NUREG-0680, "TMl-1 Restart," June 1980, p. C8-38, emphasis added.
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controlling EFW flow is not explained by GPU nor is it apparent. In any event, the THI-1 emergency procedures focus on venting of the steam generators (using the turbine bypass or atmospheric dump valves) as the principal means the operator- should use to control steam generator pressure. A review of the TMI-l emergency procedu'res in UCS's' possession indicates that the operator .
does not use steam generator pressure to control EFW- flow rate and we have nowhere previously heard this asserted. In addition, cavitating venturis in the EFW discharge. lines ninimize the potential for overcooling as.a result of excessive EFW flow, a condition in which the EFW flow instruments are allegedly accurate anyway.
Secondly, the requirement for EFW flow indication was adopted to provide
.the capability in the control room to ascertain the actual perfomance of the EFW system. This requirement was relaxed, for Westinghouse and Combustion Engineering plants, to the extent that only ~ one EFW flow indicator for each steam cenerator is required "for PWRs with U-tube steam generators becaus,e flow indication is of secondary importance in assuring steam generator cooling capability for steam generators of this desian."E Because TMI-1 uses a once-through steam generator design, EFW flow indicatidn is of primary importance.
Finally, GPU's arguments ignore the TMI-2 accident lessons learned in another respect. During the accident, the operators focussed their attention on pressurizer level and shut off the emergency core cooling system -to the detriment of core integri ty. The operators then ignored indications of extremely high temperatures in the core because they knew the incore thermo-s 26/ ' NUREG-0737, " Clarification of TMI Action Plan Requirements," November 1980, p. II.E. 1.2-4.
couples were not safety grade and thus potentially - unreliable.EI Now GPU proposes to have the operators focus their attention on the steam generator level and pressure instruments and assist the . operators in understanding how the EFW flow instruments perform, i.e., inaccurately at low flows. It is
.unlikely that such an approach can meet the requirement -that the EFW flow
- instruments "not increase the potential for operator errror."EI GPU's final response is related' to our point that GPU has turned its back on the experience of the T.MI-2 accident by putting the- operators in a position where they have to take important actions on the basis of . unreliable instruments. We noted that. during the TMI-2 accident, the opera. tors - ignored
'the themocouple readings showing extremely high core temperatures because they knew the instruments were not safety grade and thus potentially unreliable.2_9/ -gpg.s breathtaking response 'i's that the "EFW flow instrumen-tation at TMI-1, however, is safety grade."30,/ This response is remarkable on several l evel s . First, an instrument with'out reasonable accuracy cannot be said_ to be safety grade. Secondly, these instruments' are not ' reliable and cannot therefore be relied upon by the operators. That is precis'ely what the
. .undamental problem was with the _ thermocouple's'. GPU has missed the forest for the trees -- whatever the cause of the unreliability, the result is that the operators cannot be assured that the information they need to safely operate the plant is accurate.
-27/ NRC Special Incuiry Group, "Three Mile Island, A Report to the Commissioners and to the Public," January 1980, Vol .1, p.126; Vol .11, Part 3, pp. 898, 901.
28/ NUREG-0737, p. II.E.1.2-5. j g/ UCS Response at 5.
30/ , Licensee's Reply at 4. I L
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'In summary, the ~ lessons learned from the TPI-2 accident specifically require what .THI-l'. does not have -- emergency feedwater flow instruments meeting strict, detailed performance criteria to ensure . that operators can rely on them. Faced with the reality that it lacks sufficient technical competence to design accurate EFW flow instruments despite two attempts, GPU essentially attempts to argue that accurate instruments are unnecessary. Such an -argument was not advanced by GPU during the restart hearing. Its advancement at this -late date does not cure its fundamental defect -- it has no merit.
Conclusion
-The root cause of most of the difficulties discussed above is that GPU is attempting ' to patch bandaids over a fundamentally deficient EFW system. If
'the EFW system were truly safety grade, each of its component parts could be relied upon to perform its function and not to fail in ways that compromise safety. .Instead, each time GPU tries to jury rig a temporary " cure" for one part of the system's deficiencies, it causes or accentuates others.
UCS urges the- Commission at the least to reject GPU's attempt to circumvent. the short-term lessons-learned requirements for EFW flow instrumentation.
Respectfully submitted,
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Ellyn &d Weiss General Counsel
- N Robert D. Pollard Nuclear Safety Engineer Dated: January 6, 1984