ML20205B005
| ML20205B005 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 01/30/1987 |
| From: | Markey E HOUSE OF REP., ENERGY & COMMERCE |
| To: | Zech L NRC COMMISSION (OCM) |
| Shared Package | |
| ML18150A013 | List: |
| References | |
| NUDOCS 8703270530 | |
| Download: ML20205B005 (6) | |
Text
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Congre58 of tfje 1Hnitch Atateg
- pouse of Representatibes Committee on energy ant Commerte Room 2125. Rapturn house etite EmIning Washington, B.C. 20515 January 30, 1987 The Honorable Lando W.
Zech, Jr.
Chairman U.S.
Nuclear Regulatory Commission 1717 H Street, N. W.
Washington, D.C.
20555
Dear Mr. Chairman:
I Your letter of January 29, 1987 responding to my inquiries concerning the recent tragic accident at the Surry plant fails to answer one central question posed by this accident, and furthermore, it raises additional questions which speak directly to all plants on a generic basis.
l The central question left unanswered is this:
did the NRC l
have advance warning about the potential for an accident such as the one that killed 4 workers at Surry, and should the NRC have had a regulatory system is place to catch such potential failures?
A June, 1984 Engineering Evaluation Report for Karl Seyfrit, l
Chief, Reactor Operations Analysis Branch, Office for Analysis and i
Evaluation, f rom Earl J. Brown, Lead Engineer, Engineering Systems, Reactor Operations Analysis Branch, indicates that NRC staff were aware of the potential for erosion in nuclear power
{
plants.
Indeed, the memo notes that "this study identified more than 140 events related to erosion of various components" but cautions that because of a lack of reporting requirements, this number "should be considered representative of the types of degradation that can occur due to erosion rather than a complete list of events."
The memo concludes that "there are potential safety issues even though it does not seem feasible to identify a specific safety problem that requires immediate attention."
Furthermore, the Report identifies " potential constructive actions
[which include] (1) cognizance of the phenomenon for certain sites and systems; (2) identifications of specific plant equipment and physical configuration that may be susceptible to erosion; and (3) implementation of monitoring programs to detect degradation of equipment (pumps, valves, heat exchanges and piping).
l 33%39%53@ M
Th2 Hcnorcblo Lcndo W.
Zech, Jr.
Page 2 January 30, 1987 It should be noted that the initial impetus for this engineering evaluation was the rupture of an extraction steam line at Oconee 2 on June 23, 1982, and "The intent of the investigation was to identify the scope of degradation related to erosion ano assess potential generic implications."
In the aftermath of the Oconee 2 accident and other ruptures of steam lines, the NRC and the nuclear industry instituted a program of inspections and ultrasonic tests for steam systems which have identified seriously eroded steam pipes and led to their replacement.
As in other instances where problems have not been foreseen when the plants were designed, built and licensed, this inspection effort was initiated only af ter a major incident called it to the attention of both the industry and the regulators.
What disturbs me is that it appears the NRC evaluated the scope of degradation related to erosion, but implemented an inspection effort only on steam systems, thereby ignoring both the evidence and its own Engineering Evaluation Report which identifies Water Systems as " warrant [ing] consideration for monitoring as part of ongoing inservice inspection programs to detect degradation."
The above-mentioned Office Analysis and Evaluation of Operational ' Data (AEOD) Engineering Evaluation Report is quite clear in identifying water systems - in addition to steam systems "as ideal candidates for erosion and warrant monitoring for degradation and potential impact on safety related equipment."
Certainly, the industry and the NRC responded properly to this newly discovered problem of steam line erosion rupture by instituting ultrasonic tests on steam pipes.
Unfortunately, for whatever reason, the same call for action on water systems was ignored, and the result was tragic.
The AEOD Engineering Evaluation Report makes repeated reference to erosion caused by flow of water and specifically identifies particulates in the water and physical configuration as a source of erosion events.
Indeed, the Engineering Evaluation Report identifies erosion events af f ecting valves, pumps, heat exchangers and piping systems that all involve both steam and water systems, and in both BWR and PWRs, valves in water service suffered more erosion than valves in steam service, l
The accident at Surry involved a suction line to the main feedwater pump.
The AEOD Engineering Evaluation Report identifies 9 reports of erosion in the feedwater system.
Three of the reports were for PWRs.
One of the PWR report which was similar to 4 reports at BWRs "was attributed to flow patterns downstream of an orifice in an auxiliary feedwater miniflow lines."
The other 2 events involving PWRs are noteworthy.
The Engineering Evaluation Report states:
The other two events in PWRs involved erosion of J-tubes at Ginna and Surry 2 that were recently installed as one of the elements to help prevent and mitigate steam generator water hammer.
Tha H:norcblo Lcndo W.
Zech, Jr.
Page 3 January 30, 1987 Similarly, Surry 2 reported holes in 7 J-tubes and reported that all J-tubes were to be. replaced with tubes manuf actured f rom a more erosion resistant material.
[These J-tubes had been in service approximately three years prior to the erosion events.]
Based on discussions with the licensees and NRC staff, it appears there are no NRC requirements in either plant technical specifications or Inservice Inspection Rules of the ASME Code, Section CI, to cover the J-tubes.
One plant discovered the erosion inspection as part of a maintenance program.
If installation of the J-tubes to reduce or prevent water hammer relates to specific steam generator safety issues, NRR may want to consider the need for surveillance requirements.
The NRC and the industry reacted to the concern about the J-tubes with appropriate action.
But unfortunately, the NRC failed to apply these lessons learned and programs implemented to the rest of the feedwater system and f ailed to implement or require the necessary inspection programs.
This conclusion is illuminated further by the statement in the " Preliminary Metallurgical Evaluation" included in your letter which states, "[t]he piping configuration and the corrosion pattern are similar to the steam generator J-tube (except for much larger diameter) configuration and corrosion pattern that has previously been identified and well documented."
The same severe angle present in the J-tube which prompted concern was nearly duplicated in the feedwater pump line which ruptured at Surry.
A serious question the NRC needs to answer is why the lessons learned f rom the J-tube and the conclusions reached in the Engineering Evaluation Report were not applied to water systems.
Other warning flags are included in this AEOD Enginneting Evaluation Report.
While the study identified more than 140 events related to erosion of various components, "[ilt is also evident that there are many events referenced in some of the reports such that erosion may be more prevalent than the number of reports might suggest.
The Report finds that " erosion may be more prevalent than suggested by the data retrievable by a general search on erosion."
In addition to the 3 potential construction actions identified above, the Engineering Evaluation Report makes 2 noteworthy conclusions: "First, the data bass is probably incomplete because many events are not r epo r table.
- Secondly, there does not appear to be a direct relationship between these events and a specific safety problem that needs immediate attention; however, there are potential safety issues" (Emphasis added).
I am greatly concerned and puzzled as to why the NRC ignored
s Tha Honortble Lando W.
Zech, Jr.
Page 4 January 30, 1987 the plain conclusion of the Engineering Evaluation Report regarding Water Systems.
The Report states:
Many erosion events appear related to the specific water source with suspended solids (raw water, radwaste, etc.), the use of throttling de" ices such as valves and orifices, or a combination of the effects of water with suspended solids and a throttling device.
These water sources and devices may be situations that warrant review for monitorina as part of onooina inservice. inspection procrams to detect dearadation (Emphasis added).
If the NRC had not ignored this clear warning, then the tragic accident at Surry may have been prevented.
On a more generic level, I am concerned about the importance of this accident for the regulation of nuclear power.
The half-inch thick carbon steel pipe, which failed after eroding to the thickness of construction paper, was, according to Virginia Power officials, tested when it was installed during plant construction in 1972 and apparently was not inspected since.
Clearly, this particular pipe is not saf ety-related and its f ailure does not have the same impact on plant safety as the failure of a pipe in the primary system.
But the pipe rupture highlights two disturbin, trends:
one, the failure of plant components due to deterioration long before the end of their expected lif espan; and two, the inattention of the NRC and the industry to secondary systems.
The problem of plant components f ailing before the end of their expected lifetime has several critical implications.
One implication has to do with the extended operation of nuclear power plants.
In November,1986, the NRC published in the Federal Register a " Policy Statement:
Request for Comments" on extending nuclear power plant licenses beyond forty years.
In addition, the industry and the NRC are expending considerable resources evident with the intention of extending the operating lifetimes of nuclear plants beyond their originally projected forty-year life cycle.
I believe the accident at the Surry plant only serves to highlight the safety uncertainties surrounding the operation of nuclear plants as they get older.
In a rush to get a few more years operation out of aging nuclear plants, the industry and the NRC must not ignore these uncertainties.
New problems will arise which the NRC must address in a systematic regulatory f ramework and anticipate in both the licensing process and in the ongoing rulemaking proceeding.
In some respects, we are entering uncharted territory as a whole generation of plants reach age fif teen or more.
Steam pipes and J-tubes were not supposed to erode and leak or rupture, but they did.
Single phase water pipes were not supposed to f ail, but they did.
At Surry, the results are tragic.
As nuclear plants
Th2 Honorcble Lcndo W.
Zech, Jr.
Page 5 January 30, 1987 age, unanticipated problems will occur.
An NRC engineer crudely but appropriately observed recently at an NRC conference on the Surry accident, "These things are like traffic intersections.
Once there is a few accidents, then you know to put up a traffic light."
The challenge facing the NRC is to conduct research and oversight to anticipate where these problem " intersections" are.
The obligation f acing the NRC is to apply its research in a comprehensive way so as to prevent repetition of these and other problems.
The June 11, 1984 AEOD Engineering Evaluation Report casts a spotlight on the problem of erosion in plant systems.
Unfortunately, the NRC only saw half the problem -- erosion in steam pipes.
By deciding not to implement the same testing and monitoring program for water systems as was applied to steam systems, the Commission f ailed in its obligation to safeguard plant workers and the public.
The specific problem of erosion of water pipes.and the generic problem of rapid deterioration of plant components is of ongoing concern to me.
In order to help my understanding of this issue, please answer the following questions:
4 1.
When did regular testing and monitoring of steam pipes begin?
What prompted this action?
Please provide all appropriate documentation.
2.
Why did the NRC not require testing and monitoring on water systems, given the data in the AEOD Engineering Evaluation Report?
Please explain in detail, including all internal letters and memoranda on this subject.
3.
Did the NRC provide licensees with the June 11, 1984 Report on Erosion in Nuclear Power Plants, or any of its conclusions?
If so, when?
If not, why not?
4.
Are there other systems the NRC has identified which were expected to last for the life of the plant but which may be subject to early failure?
Please identify each such system, and any NRC research or inspection effort dedicated to each system.
5.
What actions does the NRC plan in response to the Surry accident?
Does the Commission expect increased inspection of secondary systems?
If not, why not?
i 6.
Please provide a status report regarding the Commission's review of plant life extension.
Include in the status report all NRC programs and industry programs j
dedicated to this effort, how much money is being spent, i
and what technical questions are being addressed.
Please provide a response to this letter by close of business
The Honorable Lando W.
Zech, Jr.
Page 6 January 30, 1987 on February 23, 1987.
Sincerely, N
Edward J. Mark Member of Congr a s O
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