ML20151K868
| ML20151K868 | |
| Person / Time | |
|---|---|
| Site: | Crane, 05000000 |
| Issue date: | 05/20/1985 |
| From: | Malsch M NRC OFFICE OF THE GENERAL COUNSEL (OGC) |
| To: | |
| Shared Package | |
| ML20151K691 | List:
|
| References | |
| FOIA-85-409, TASK-PINV, TASK-SE SECY-85-176, NUDOCS 8505310659 | |
| Download: ML20151K868 (12) | |
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May 20, 1985
.SECY-85-176 POLICY ISSUE (Notation Vote)
For:
The Commission From:
Martin G. Malsch Deputy General Counsel
Subject:
APRIL 12 UCS LETTER RE STAFF TESTIMOliY IN RESTART PROCEEDING e
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,v Martin G. Malsch Deputy General Counsel Attachments:
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UCS letter 2.
Staff response Draft staff requirements 3.
memorandum Commissioners' -comments or consent should be provided directly to the Office of the Secretary by c.o.b. Tuesday, June 4, 1985.
Commission Staff office comments, if any, should be submitted to the Comnissioners NLT Tuesday, May 28, 1985. with an infor-mation copy to the Office of the Secretary.
I.? the paper is of such a nature that it requires additional time for analytical review and comment, the Commissioners and the Secretariat should be apprised of when comments may be expected.
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Nunzio J. Palladino, Chairman Thomas M. Roberts, Commissioner James K. Asselstine, Comissioner Frederick M. Bernthal, Commissioner Lando W. Zech, comissioner U. S. Nuclear Regulatory Commission Washington, D. C. 20555 Gentlemen:
We are writing to bring to your attention recent statements by the NRC
' staff which directly contradict its sworn testimony in the 2I-1 restart pro-ceeding and which raise questions about the basis for concluding that MI-l can be safely operated.
As you are undoubtedly aware, the effectiveness of the so-called boiler-condenser mode of natural circulation for decay heat removal was a central safety issue in the MI-l restart case raised and pursued by the Union of Concerned Scientists.
Indeed, concerns about the reliability of the WI-1 decay heat removal mechanisms led the Appeal. Board to hold four days of reopened hearings in March 1983.
UCS has learned that sworn testimony by the staff during the reopened hearing has recently been directly contradicted by the staff's statements in support of NRC's proposed research budget.
During the reopened MI-1 hear-ings, the staff testified that, although additional testing was planned,
"[t]he purpose of the testing is not to confirm the effectiveness of boiler conder.ser decay heat remeval."
lbwever, last month the NPC staff stated that an area where research is needed regarding WI-l restart is a " test to assess the effectiveness of the boiler-condenser process to remove decay heat
Background
here are a limited number of theoretically possible ways to remove decay heat from the mI-1 reactor coolant system (RCS) following a small break loss-the type of accident which occurred at BI-2.
Se of-coolant accident processes discussed in the restart proceeding were decay heat removal through the brea'k itself, by a " feed and bleed" process, by liquid natural circulation in the RCS, and by the tuu-phase (licuid water and steam) boiler-condenser rede cf natural circulation in the ECS.
(Forced circulation of the RCS is net
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For ' breaks smaller than a certain size, heat removal through the break itself is insufficient.
The " feed and bleed" process - cannot be relied upon tecsuse. the evidencs in the reopened husrings ;*J. the ;gpea; b :d v..er.in.
"to state conclusively that feed and bleed will successfully provide core cool-ing at MI-1." [Ref.1]
Liquid natural circulation will be blocked following some small break loss-of. coolant accidents by steam formation in the reactor coolant system.
Thus, for some break sizes, the boiler-condenser mode of cooling is the only possible way to provide adequate decay heat remeval for M I-1.
i Discussion At the time of the reopened hearings, the NRC staff was directed by the Appeal Board to respond to a series of questions about boiler-condenser cooling, inter alia. The staff testified under oath:
i The staff has concluded that the heat. transfer mechanisms involved in the boiler-condenser process are adequate to remove decay heat from the reactor system and will prevent core uncovery if at least one train of ECCS is operable.
[Ref. 2]
Although the Appeal Board recognized that the EC's computer calculations did not predict the occurrence of the boiler-condenser mode for MI-1, it relied upon B&W computer calculations, in combination with the staff's endorse-ment of the heat-transfer equations used by B&W, as its basis for concluding that "the boiler-condenser method will satisfactorily remove decay heat at 2I-1."
[Ref. 3) the staff acknowledged during the reopened hearings that "there are no I
experimental data from a test facility geometrically similar to the B&W reactor design confirming the boiler condenser mode of natural circulation."
1
[Ref. 4)
In the absence of any test data, the staff claimed that computer analyses " demonstrate the efficacy of boiler condenser natural circulation,"
and explicitly denied that testing was necessary to confirm the effectiveness of the boiler-condenser process:
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The purpose of the testino is not to confirm the ef fective-ness of boiler condenser decay heat removal.
Father,. its purpose is to satisfy the confirmatory research needs for the E&W design, and to provide additional confirmation of opera-ting guidelines.
[Ref. 5, emphasis added.)
The Appeal Board, noting that "[f]uture experimental work is planned to investigate the t:ciler-condenser mode of cooling at an integrated systens test facility (GERrA)," ruled that:
he believe that the heat remeval calculations include sufficient conservatisms to make a full-scale test of the
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boiler-condenser process at mI-1 unnecessary before restart.
However, w reco nend that this ecoling process te studied further ar. part of continuing research in order to increase the current knowledge of thermal-hydraulic behav,ior during small break loss of coolant accidents.
(Ref. 6]
In other words, while endorsing research to gain further knowledge of plant behavior, the Appeal Board accepted the staff's position that there is no serious question that the boiler-condenser mode will be effective in removing decay heat.
Wis rulirg was necessary for restart since, as we explain above, the record precludes reliance on all other heat removal modes for certain small breaks.
Last month, in response to inquiries from Congressman Udall's staff concernirg the NRC's research budget, the NRC staff delineated " areas where continued research is needed."
Among those applicable to MI-1 are the following:
Issues and Concerns Regarding Adequate Decay Heat Removal Capability in TMI-l Restart (Applicable to all B&W Designed Plants):
o Test to assess the effectiveness of the boiler-condenser process to remove heat from the reactor coolant and main-tain natural circulation.
l o Use of high-point vents to assure natural circulation and I7 long-term adequate core cooling.
(Ref. 7, emphasis added.]
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Thus, there is a direct contradiction between the staff's sworn testimony j
that "the purpose of the testing is not to confirm the effectiveness of boiler condenser heat decay heat renoval," and the staff's current claim that an area v
where research is needed regardf rg mI-1 restart is a "[t]est to assess the effectiveness of the boiler-condenser process" to remove decay heat.
In addition to arguing against reliance on inconsistent computer predic-tions (in the absence of any experimental data) to judge the effectiveness of the boiler-condenser coolirg, UCS also argued "that the boiler-condenser process cannot be considered sufficicatly reliable without an assurance that the asstanptions regarding operator action made in the ccenputer analyses are appropriate." (Ref. 8]
Our concern was (and remains) that if the operator were confronted by unpredicted plant behavior durirg the boiler-condenser cooling mode, this might result in incorrect operator actions causing serious consequences.
However, the Appeal Board's " limited reopening of the record excluded the adequacy of mI-1 emergency procedures."
(Ref. 9]
We brino this ratter te your attention now because we recently obtained a December 30, 1981, memorandut indicating that the tv oca:t nad concerns similar to UCS's regarding the potential for incorrect operator actions.
Se purpose of the staff memorandu, was, in part, to identify experirental data
4 needed to confirm the predicted behavior of E&W plants during small break locs-of-ccolant accidents.
W.e staff stated:
Recent E&W analyses have shown the syste. pressure to behave in a cyclic manner that could be confusino to the operator during certain small break conditions.
We do not know if the unicue oscillatory phenomenon is real or an artificiality of the analyses.
Recent analyses of small breaks in E&W plants by (los Alamos National Labora-tory] do not show the repressurization phenomenon calculated by B&W.
We believe the predicted phenomenon could produce false symptoms of other events..
7.4 lead to incorrect operator actions which could result in more severe conse-quences than now predicted for the SBLOCA [small break loss-of-coolant accident].
At present, we have no confirmatory integral systerrs data with which to verify the acceptability of the predicted behavior of transients and accidents including small break LOCAs in B&W designed reactors. Also, the long-term hydraulic stability of the plant following a SBLOCA has never been analytically or experimentally confirmed.
(Ref. le, emphasis added.]
Apparently, there was little change in the factual information available to staff between December 1981 and the March 1983 reopened hearings regarding plant -behavior during boiler-condenser cooling.
During the reopened hearings, the staff described an intermittent " chugging" behavior and attenpted to explain actual plant behavior.
However, the Appeal Board noted that the staff's explanation "was not illustrated in the graphs (of the computer predictions) and appears to us to be contrary to some basic laws of physics."
(Ref. 11]
As we noted above, the staff testified in the reopened hearings that one purpose of further testing of the boiler-condenser process was "to provide additional confirmation of operating guidelines."
This is clearly not the same as the staff statement in December 1981 that "the predicted phenomenon could produce false symptoms of other events and lead to incorrect operator actions which could result in more severe consequences than now predicted for the SBIOCA."
During the reopened hearings, the staff never suggested that the lack of understanding of plant behavior during boiler-condenser cooling could lead to consequences beyond the licensing basis.
Cn the contrary, when UCS attempted to demonstrate precisely this point, the staff succeeded in cutting off any questioning on the grounds that this went beyond the scope of the hearing. As UCS stated in response to'the cbjection:
It is our positi'on that a computer analysis or any of the. many cccpater analyses we have been offered -- and :
think there are five or six between the various witnesses in this case - of system tehavior is only good se far as !*
corresponds to what one would actually see happening in the plant over the period of time that the analysis atternpts to make predictions.
In the case of Snall-Break IDCA in particular, what is happening in the plant has a substantial amount to do with what the operator perceives and how he acts upon what he perceives.
We don't intend at this point to go into any of the details of the proce.$ures, but we think it is a highly relevant point.
If the operator cannot be expected to distinguish, for example, between a anall-Break trCA or some other accident, and if on the basis of that he does not take the appropriate actions, and (the] plant does not conform to what the assm.ptions are in the computer analyses, then the computer analyses are simply not useful.
I think it is important to renember how the mI-2 accident happened, where an operator turned off emergency core cooling because he was afraid that his plant was going solid, because his indications led him to believe that that was happening and that that was worse, and we think that wet are addressing and will be addressing throughout the examination of these witnesses whether an analogous situation doesn't exist now for M I-1.
[Ref. 12]
UCS continues to believe that further testing is needed, prior to restart, to assure that plant behavior is sufficiently well understood to reduce the potential for incorrect operator actions or, as the staff phrased it, "to provide additional confirmation of operating guidelines." Please note that we do not wish to raise anew here the question of whether this issue was within or outside the scope of the reopened hearing.
Fortunately, the Conris-sion's responsibility is not demarcated by such distinctions, ne Connission has the responsibility to assure the overall safety of mI-1, regardless of
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whether a question falls within the mited scope of any particular hearing.
Conclusion There are at least two major safety questions related to 2I-1 which are the subject of future research and testing.
Se first is whether the boiler-condenser mode of cooling is adequate to remove decay heat.
We second is whether plant behavior is sufficiently understood so that the operator will take the appropriate actions and will not take actions that would add to the seriousness of the accident.
We therefore request the Commission to establish the answers to the l
fellowirg questions:
i 1.
What factual information does the rnC expect to obtain fron future research and testirg that it does not now have regardire the adequacy of decay i
heat removal for m I-1?
2.
khat factual information does the NRC expect to obtain frem future research and testing that it does not now have regardirg the effectiveness of tr.e tc Gt:-c:,...ense:
..du of de:ay r. cat re. oval for W I-17 3.
hhat factual infor: atier. does the NRC expect to obtain frem future research and testing that it does not now have regarding the 9tI-1 plant behavior during boiler-cendenser cooling?
4.
What is the current ' oasis for believing that boiler-condenser cooling would be effective for D'.I-l?
5.
htat is the current basis for believing that 9tI-l plant behavier during boiler-condenser c.ooling would not lead to incorrect operator actions?
6.
If the factual information currently available to NRC establishes the adecuacy of decay heat removal and the effectiveness of teiler-cendenser cooling for DtI-1, why should the planned research and testing be paid for by NRC?
In addition, we request that the Commission refer this matter to CIA to detemine whether false or misleading statements were made by the staff.
Sincerely, Pobert D. Pollard Nuclear Safety Ehgineer
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Ellyn R. Weiss General Counsel
References:
See next page.
cc: 91I-1 Service List O
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Beferer.ces 1.
AI.AS-729,17 NRC 814, 252 (19E3).
2.
NRC Staff Testimony of Brian W. Sheron and Walton L. Jensen, Jr. in Response to Appeal Board Cuestions 2, 4, 5, 6, 7, 9, le and 11, served February 16,1983, p. 6, ff. Appeal Tr. 83, March 7,1983.
3.
AIAB-729,17 NRC 814, 842 - 844 (1983).
4.
NRC Staff Testimony of Brian W. Sheron and Walton L. Jensen, Jr. in Response to Appeal Board Questions 2, 4, 5, 6, 7, 9, le and 11, served February 16, 1983, p. 8, ff. Appeal Tr. 83, March 7, 1983.
5.
Id., p. 9.
6.
AIAB-729,17 NRC 814, 848 (1983).
7.
Memorande from Enrico F. Conti, Office of Nuclear Regulatory Research, to
'Ihomas Rehn, Office of the Executive Director for Operations, March 13, 1985, enclosure, " Areas Where Continued Research is Needed," p. 2.
8.
AIAB-729, 17 NRC 814, 846-847.
9.
Id., n. 127.
- 10. Memorande from Harold R. Denton, Office of Nuclear Reactor Regulation, to Robert B. Minogue, Office of Nuclear Regulatory Research, " Request for the Conceptual Design of a Facility for the Study of B&W and CE Integral System Characteristics," December 30, 1981, pp. 2, 3.
- 11. AI.AB-729, 17 NRC 814, 845, n. 118.
- 12. Appeal Tr. 579-571, March 17, 1983. See also pp. 585-588.
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