Zirconium is reactive Old News

John W. Simpson (1914 - 2007) had a diverse career with Westinghouse and he left behind a great record with his book, Nuclear power from underseas to outer space, copyright American Nuclear Society, 1995.  Following is copied from two pages, and it is revealing as well as entertaining. 

Core Exit Thermocouples, Some Interesting history

This is an early document.  Click to view the entire page.  Core exit thermocouples have survived as a primary warning of core uncovering.  In the case of LOFT experiment L2-5, core exit thermocouples severely misled the plant operators.

And here is a the related analysis from Oak Ridge National Laboratory:

And, here is a detailed analysis by ORNL:
http://www.ornl.gov/info/reports/1982/3445605701648.pdf
Here is the cover page and one paragraph from page 81.  In general, the report supports HJTCs as monitors of inadequate core cooling.

Core Exit Thermocouples

So, I've been away for a while.  There is a peristent mindset that core exit thermocouples are great for detecting inadequate core cooling.  More later on this.

UHI Ultra High Risk, October 3, 1984 28th Anniversary

So, today is the 28th Anniversary of my infamous memo.

Where are all of the participants now?

Some are hiding and some are lost.  Sandia still is alive and I'm working on getting the unfinished business taking care of.

Right now I have to leave town, but I'll be back to celebrate this 28th anniversary!

UHI Ultra High Risk, October 3, 1984: Unfinished Business

Yes there is unfinished business.  I've discussed the work by Sandia.  Duing 2006, I did not get approval to present a POWER POINT discussion of this.  Here is the abstract that I submitted.  The report by Sandia was very restricted in scope by the NRC, very likely because the NRC then, like now, did not really have any skills in analyzing field experience and relating that to risks. There is a CATCH, those who may be good at it are not allowed to do it. 

Here is the abstract that I submitted to the program manager at INL during June 2006.

the

UHI Ultra High Risk October 3, 1984, OHI and Watts Bar

UHI Ultra High Risk, October 3, 1984, Led to an Abnormal Occurrence Report to Congress

This is my seventh consecutive entry in matters stemming from my EPRI-NSAC Memorandum, UHI Ultra High Risk, October 3, 1984.

Yes, my NSAC Memorandum, UHI Ultra High Risk, led to an Abnormal Occurrence Report to Congress.  Here it is, click on it to enlarge and back arrow to get back here.

So, on January 28, 1985, Denton as Director of the Office of Nuclear Regulation, reports, "This condition is beyond the design bases for the plant and is not specifically analyzed in the safety analysis report."  Denton continues: "The effect of nitrogen in the reactor during a LOCA has not yet been analyzed, however, NRR is placing a work order with Sandia National laboratory (SNL) to assess the effect of isolation valve failure during a large LOCA in a UHI plant."

A year later, Sandia submitted its analysis to NRC, but noted that the report had information proprietary to Westinghouse, and NRC did not make the report available to the public. 

I  left the matter alone for about 10 years, but then I went after the NRC for the report.  Nothing was producing results, so I faxed the following to the Chairman, NRC on May 30, 1994.

And on June 17, 1994 I was sent the following reply.  It reveals that NRC had not even had a copy of the Sandia report and that "extraordinary measures" were required to "locate and acquire" a copy of the letter report.  What in the world did  NRC do with this Sandia report that was highlighted in the Abnormal Occurrence Report to Congress?  We will never know.  Moreover, I was not promptly sent the report once NRC found it. 

After a while, I was sent a somewhat illegible copy of the report. Following is from page 13 or is it 15? It is not obvious from the poor copy. This Sandia letter report suggests that failure of the UHI isolation valves to close may be beneficial because of the addtitonal water that is injected into the upper head. 

About six years ago I was not successful in getting NRC to perform evaluations of the UHI situation that prevailed during 1984.  Following is an e-mail exchange that I had with Dean Dobranich of Sandia who had performed the analyses of UHI for the NRC during 1985.   Work at Sandia proceeded during 1985 and was reported to NRC in periodic contacts during 1985 and in a letter report during January 1986.

NRC did not adequately fund Sandia for the UHI analyses and the scope of work was far too narrow.  For example, with four out of four liquid level detectors reverse connected there was no way of determining the amount of water that would be injected.  In the extreme, but not improbable case, there would be no water injected.  More likely, there would be some water available, however, the amount would likely be substantially less than 1800 cubic feet.  Instead of 1800 cubic feet of water, there might be 400 cubic feet of water and 1400 cubic feet of high pressure nitrogen.

Moreover, the water would be saturated with dissolved nitrogen which would be released during the injection.