Comments on Decay Pipe Review

**July 9, 2001**

# Design & Engineering of the Pipe

[Presenter: D. Pushka]{.underline}

1.  ([Reviewer: J. Anderson]{.underline}) Consider removing one (1) foot
    of concrete from each end of the decay pipe to allow for easier
    installation and possible removal of the decay pipe ends in the
    future. The current design leaves a marginal amount of space for
    welding the flanges on.

2.  ([Reviewer: J. Anderson]{.underline}) Consider the addition of a
    water drain port at the downstream end of the decay pipe.

3.  ([Reviewer: J. Anderson]{.underline}) Review the specification of
    the vacuum pump to insure water from pump down operations does not
    cause a problem with contaminating the vacuum pump oil.

4.  ([Reviewer: J. Anderson]{.underline}) Review the use of the water
    soap testing of welds. Weld leaks after the pipe has been grouted in
    place will be near impossible to repair.

5.  ([Reviewer: J. Anderson]{.underline}) How will the grout shrinkage
    effect the decay pipe uniformity, alignment tolerances, cooling
    pipes, etc. A possible test of the contractors plan, when submitted,
    should be considered. Once the decay pipe is grouted in place, there
    are no possible repairs.

6.  ([Reviewer: J. Anderson]{.underline}) Have the effects of radiation
    damage to the PVC piping been reviewed for use as an insulator to
    the copper cooling piping.

7.  ([Reviewer: J. Anderson]{.underline}) A drip ceiling should be
    considered for covering the muon chamber electronics, the decay pipe
    vacuum systems, absorber RAW water system, and instrumentation racks
    near the absorber.

8.  ([Reviewer: J. Anderson]{.underline}) The upstream cooling water
    manifold design should be reviewed to insure a single cooling pipe
    could be isolated in the event of a leak. The design should be such
    that individuals performing the repair would receive minimal
    radiation exposure.

9.  ([Reviewer: J. Anderson]{.underline}) With the deletion of the
    hadronic hose from the project, is there still a need for cooling
    the decay pipe?

10. ([Reviewer: S. Childress]{.underline}) I am concerned that current
    design of the cooling pipe manifold does not provide viable options
    for isolating a bad pipe and continuing to flow water through the
    remainder. It seems not very realistic to attempt to remove manifold
    shielding, isolate which pipe leaks, and redo manifold to isolate in
    a hot radiaiton area - as I believe was discussed. Manifolding
    enabling independent flow loops should be done at the beginning,
    along with isolation capability OUTSIDE the shield.

11. ([Reviewer: S. Childress]{.underline}) A vacuum access port near the
    upstream end, as was discussed, seems very important. Best would be
    a small diameter side access pipe - several inches in diameter (a
    reduced size version of the 24\" downstream access port), where the
    port extends outside the shield. Each - upstream and downstream -
    should have flanged, not welded ends. With the flanges outside the
    shield, and use of double metal seals, these would be very robust -
    and enable access options.

12. ([Reviewer: M. Gerardi]{.underline}) I could be mistaken but the
    pumps are slated to be near the closed loop system which will be
    behind locked gates the decision to place the pipe against the rock
    has groundwater implications. Re-calculations should be considered.

13. ([Reviewer: M. Gerardi]{.underline}) PVC is a poor choice of
    insulator if the resulting dose rates in the region are high.

14. ([Reviewer: M. Gerardi]{.underline}) There does not appear to be any
    means for locating, let alone repairing, a vacuum leak should one
    occur once the system is activated with beam. If there is an intent,
    the procedure should be developed.

15. ([Reviewer: M. Gerardi]{.underline}) My guess would be that acces to
    the pipe, once activated, will be difficult if not impossible. Is
    there a plan \"B\" ?

16. ([Reviewer: M. Gerardi]{.underline}) If water is used for decay pipe
    cooling it will likely need to be a closed loop, even if from only a
    sampling standpoint to ensure discharge requirements. No one will
    allow discharge without analysis.

17. ([Reviewer: M. Gerardi]{.underline}) I might have overlooked this
    but, can the cooling lines be further away radially to remove the
    heat ? Do they really need to be close by ?

18. ([Reviewer: M. Gerardi]{.underline}) Cracking potentials of the
    concrete not only jeopardize the cooling abilities but contribute to
    groundwater activation because of the leaks.

19. ([Reviewer: N. Grossman]{.underline}) It was mentioned that there
    would be radial cracks in the concrete as it cures. I do not
    envision this being a radiation issue since access to this area will
    be very limited. But I would like to know how large one envisions
    these cracks will be and is there a possibly of somewhat large
    pieces of concrete breaking off if there are a lot of these cracks.
    Once again, I do not see this as a concern, but something that would
    be nice to know about up front.

20. ([Reviewer: N. Grossman]{.underline}) I believe the cooling pipes
    will be surrounded at some level with PVC? If so, are there any
    issues with PVC and radiation damage over the years? It can release
    chlorine isotopes upon activation.

21. ([Reviewer: D. Jensen]{.underline}) Vacuum Gauges: I would suggest a
    couple at each end. I am a strong believer in redundancy. Allows one
    to understand the \'systematic error\' and to maintain continuity of
    measurement WHEN one of the gauges fails. Dave Pushka suggested that
    there should be pipes to a lower radiation area where these gauge(s)
    might be mounted. If necessary, can always use pure metal gaskets
    (e.g. conflat - Cu-steel seals) to avoid any possible degredation of
    the seal over time, to make seals for the instrumentation.

22. ([Reviewer: D. Jensen]{.underline}) The question of a \'person
    port\' seemed to get a lot of discussion. It is clearly the hope the
    designers that the the system be closed up once and for all - no
    leaks and no problems for 10 years! The only flanged port is the
    pumping port (and I hope some gauge ports).

23. ([Reviewer: D. Jensen]{.underline}) I am still concerned that there
    is differential motion of sections of the pipe under localized
    heating. The ends are assumed constrained. Much of the heat load is
    near one end. The compressional strain is taken over the full length
    of the pipe. The stress is generated by the heating is a small
    fraction of the total length. If the heated region moves. then the
    stiffing rings which are imbeded in concrete will experience a large
    shear force. How the heating progresses is complex. The steel is
    about 3x the density of the low densitiy concrete, and has much
    higher thermal conductivity. How the differential heating between
    the steel and concrete will take place, particularly during the
    first period of beam, is obviously complex. A worst case model would
    be to assume the steel heats but the concrete does not, and examine
    the differential motion and see what the forces on the stiffing
    rings are.

24. ([Reviewer: T. Leveling]{.underline}) I strongly suggest that the 2
    foot diameter manway not be a welded closure. Instead a gasketed
    closure should work quite well. If access is EVER required through
    the manway, a gasketed closure is certainly going to be easier to
    manage. Contrary to statements made in the meeting, leak tightness
    of a gasketed closure should not be a problem.

25. ([Reviewer: T. Leveling]{.underline}) There are several problems
    with setting the decay pipe which perhaps could be attacked in
    unison.

    a.  I would not run cooling through more of the decay pipe region
        than necessary. It would be sensible to make a break in the
        decay pipe pour to allow for the decay pipe cooling plumbing to
        turn around and for personnel access just in case isolation or
        repair of a broken run is necessary. Portable shielding blocks
        could be used to fill in the pour.

    b.  The use of PVC cooling piping would solve the corrosion problem
        discussed in the presentation. It should be straight-forward to
        determine at what distance from the decay pipe surface the PVC
        should be set to avoid radiation damage over the life of the
        experiment.

    c.  I didn\'t get the impression that personnel access into the
        decay pipe after construction has been very carefully thought
        out. I think it would be wise to get advice from the fire
        department and some safety professionals on the size of the
        access port. I think 2.5 to 3 feet would more reasonable if
        there\'s a chance people have to make an entry.

    d.  I realize it\'s the contractor\'s problem to set the pipe
        straight in the cement. The upward force on the pipe due to
        buoyancy works out to about 4200 lbs per linear foot. Blocking
        the pipe from the ceiling seems like a reasonable way of holding
        the pipe in place. The bearing surfaces would have to be
        calculated to prevent deformation of the decay pipe. Support of
        the pipe from below must also be an issue. One could consider
        filling the decay pipe with water temporarily during the
        concrete pour to further reduce the buoyancy force to about 2400
        pounds per linear foot.

    e.  It\'s quite likely that vibrators will be necessary to work the
        concrete in around the decay pipe. Some care will be necessary
        to prevent damaging the decay pipe cooling tubing. This is
        another good reason not to continue cooling for the whole length
        of the decay pipe. f.) Dixon mentioned that it\'s a well known
        problem that pipe wrap can lead to excessive corrosion. I
        didn\'t catch if that was in soil, concrete, both, and whether
        there were other contributing factors. It\'s not clear then why
        inserting Cu tubing in PVC is a good idea unless there are no
        breaks in the PVC run. Again, with concrete vibrators used
        around the decay pipe, care will have to be taken to ensure that
        the PVC is not damaged. To summarize, all of these issues should
        be considered simultaneously in the decay pipe design. The
        bracing of the decay pipe, shell stiffeners, access to cooling
        plumbing and support and installation of the cooling plumbing
        are interrelated. I think NUMI project management should work
        aggressively with the contractor on this aspect of the project
        to ensure it is done well. I didn\'t get the impression this was
        thought to be possible without incurring some tremendous cost.
        Since the pipe doesn\'t exist yet, it can\'t be too late to get
        it right.

26. ([Reviewer: P. Martin]{.underline}) The decay pipe fabrication and
    installation tolerances are quite tight. The statement in the spec
    that any out-of-position tolerance must be fixed is almost absurd.
    Once this is cast in grout, fixing it will be very expensive, and
    the arguments over whose responsibility it is will delay the
    project. The NuMI project needs to understand the real implications,
    both to physics and cost ramifications of these requirements. We did
    not hear much discussion of the support of the pipe. A good support
    design is critical to achieving the necessary tolerance. A plan
    should be developed for the QC to assure that the pipe meets the
    design tolerance prior to grouting. Since the pipe will want to
    float as the grout is placed, perhaps additional supports are
    required. Not knowing the procedures that Healy will use puts the
    project in an awkward situation of trying to plan for all possible
    methods. A better approach is, through contracts, to insist on a
    detailed plan from Healy. Stress that this will allow us to work
    with them to meet the required tolerances. There are pitfalls we are
    all aware of here...we cannot tell the contractor what to do without
    our assuming liability for the results...but we can lend them
    calculational support or point out problems that they may not have
    thought of. We can do some of this without any information from
    them; e.g. as a function of spacing of infinitely stiff supports,
    what is the expected sag due to gravity and deflection due to
    buoyancy of the pipe? Although confidence was expressed in the
    ability of CBI to do a good job, the MiniBooNE tank was considerably
    out of specification. You might talk to Peter Kasper about that. I
    would also recommend adding a stiffener ring, perhaps a special,
    larger one, at the point where the concrete/grout stops at each end
    of the decay pipe, to help maintain the circular shape. This will
    make mating to the end piece easier.

27. ([Reviewer: P. Martin]{.underline}) The cooling piping appears to be
    very expensive because of its impact on the overall Healy schedule.
    There is only one way to fix this: make the installation simpler.
    The design appears to be somewhat overkill, at least if I am
    interpreting the temperature plots correctly. The bulk of the energy
    deposition is only in the first 100 m or so, and yet the cooling
    pipes extend over the entire 2200 foot length. This is extending the
    installation time, and driving up the cost. Although we do not know
    in what sequence Healy will do the decay pipe installation, if they
    start at the upstream end, then perhaps the majority of the cooling
    pipes, around the upstream end, could be installed concurrently with
    the downstream decay pipe. The NuMI project should evaluate
    alternate cooling designs, in which less cooling is installed in the
    second half of the decay pipe. Perhaps none is needed there. (In the
    case of MiniBooNE, although the beam power is only 30 kW, it is
    concentrated over a much smaller region, so the energy density may
    not be all that different. The only reason we went to cooling at all
    was to keep the liner, which is 7' from the decay pipe wall, at a
    safe temperature.) There was considerable concern expressed about
    the possible galvanic action between the copper piping and the steel
    decay pipe. As I pointed out during the review, the copper pipes are
    much closer to the steel than they need to be...the energy
    deposition is spread out over the first foot or two radially. A
    brainstorming session might be useful to come up with some other
    ways of mounting the piping somewhat further away from the decay
    pipe, and thus avoid any possible contact. As an example, instead of
    or in addition to using the stiffening rings, (which then needs all
    the necessary holes drilled), why not some separate, very cheap
    material (molded plastic?) that supports the pipes and simply gets
    cast in place. (By the way, you need to worry about the buoyant
    forces on the pipes too!)

28. ([Reviewer: P. Martin]{.underline}) With regard to the
    specifications, I have already commented on some things above, but
    here are a few more. First, given the safety problems with Healy to
    date, the rigging issues for the decay pipe need a written safety
    plan, approved by the lab. On pipe fabrication tolerance, there is
    the 1/8" tolerance on the straightness of any 10' section of pipe,
    but no tolerance is given on the parallelism of the ends. If the
    ends aren't parallel, it will be very difficult to attain the
    overall finished straightness tolerance.

29. ([Reviewer: A. Para]{.underline}) Stated tolerances on the decay
    pipe placement are of the order of 1 inch. This is probably not very
    easy for such a long, heavy object, cast in concrete. Several ideas
    were put forward how to ensure meeting them, but this is probably a
    futile exercise without details of the planned installation process.
    On the other hand these tolerances seem to be grossly overestimated
    for the case of low, or even medium, energy beam. A second half of
    the decay pipe does contribute a very small fraction (like 10%) of
    neutrinos: clearly the exact position of the end of the decay pipe
    is immaterial. Even the very existence of the decay pipe there is
    inconsequential.

30. ([Reviewer: A. Para]{.underline}) Decay pipe is 625 meter long. This
    length was well justified for the high energy beam, which is
    extremely unlikely to be ever used. The second half of the decay
    pipe is of very little value for medium or high energy beams. This
    is due not only to the pion lifetime effect, but , chiefly, due to
    the fact that low energy pion beam has a significant angular
    divergence and pions hit the wall of the decay pipe within the first
    100-150 meters.

31. ([Reviewer: A. Para]{.underline}) The angular divergence of the beam
    (see 4) leads to the energy deposition concentrated in the first
    section of the decay pipe. If we need to cool the decay pipe (and
    this need was not well demonstrated/justified), it is certainly
    sufficient to limit the cooling to the first section only. Cooling
    seems to have a very major impact on cost/schedule. I think it needs
    to be re-addressed. This is in particular so, as it seems to have
    possible detrimental side effect on the integrity of the decay pipe
    itself (galvanic action). I would like to point out that our
    groundwater protection limit is evaluated assuming an inflow of
    water into the tunnel. This water is collected at the bottom of the
    decay pipe. This water will cool down the decay pipe and the
    surrounding concrete shield irrespective of any man-made cooling
    system.

32. ([Reviewer: A. Para]{.underline}) There were no details of the
    concrete shield construction offered. I understand that the
    thickness of the concrete shield is varying with distance to take
    advantage of the energy deposition profile and to minimize costs of
    the installation. It would certainly complicate the process of
    installation and create new classes of problems. None of this was
    mentioned at the review.

33. ([Reviewer: A. Para]{.underline}) There is very little we can
    monitor about our beam line. The far and near detector spectra are
    closely related, but the principal difference in the observed
    spectra is related to the effective distance from the decay point to
    the near detector. This is so, because our near detector is so
    close. The most important beam characteristics, determining our
    systematics is related to the beam angular divergence. This is, in
    turn related to the profile of the energy deposition along the decay
    pipe. Hence: I think it is worthwhile to consider some detectors
    placed along the length of the decay pipe to provide us information
    about the energy deposition. Thermocouples? Beam loss monitors? They
    could be cast into concrete, or better yet, sobe boxes can be cast
    and detectors place there later..

34. ([Reviewer: G. Rameika]{.underline}) A concern that emerged was what
    if after the pipe is installed in concrete it is found to be way out
    of alignment tolerance. Someone at the review said that Healy would
    likely just ask us to accept it any way. What is the consequence if
    something like that happens? It wasn\'t clear to me that we really
    know how much sag or wiggle is acceptable. (I guess I\'m not
    convinced that the 2cm spec is a valid requirement from a physics
    point of view.) I\'d like to see the physics requirement on the pipe
    alignment more clearly demonstrated.

35. ([Reviewer: G. Rameika]{.underline}) I think it was obvious that the
    cooling pipes are not really needed ( they were left over from the
    hose). I\'m concerned that keeping them and using them adds
    unnecessary complexity that will only lead to operational problems.

36. ([Reviewer: R. Sanders]{.underline}) Decay Pipe Out-Of-Roundness:
    There appears to be concern that the wet cement, when it is poured,
    will distort the decay pipe into an oblong cross section at the
    ends. It could then become difficult to weld the end caps onto the
    decay pipe. There was also mention made that the contract with Healy
    may need to be changed to prevent or deal with this potential
    problem. In light of this, it is appropriate to look at the
    implications of the out-of-roundness specifications in section UG-80
    of the ASME Boiler and Pressure Vessel Code. UG80 must be followed
    in order to use UG28 of the ASME code. Therefore, since the
    contractor determined the external pressure rating of the decay pipe
    using the equations from UG-28; the decay pipe must satisfy the
    roundness requirements of UG 80. If, after the decay pipe is
    installed and after the concrete is poured, the decay pipe does not
    satisfy the roundness requirements of UG 80 there are implications
    for both Fermilab and the contractor. For Fermilab, the ES&H manual
    chapter 5033 requires the decay pipe, as a vacuum vessel, be built
    to the ASME code. This is a safety standard, not a contract
    specification that can be changed at will. A damaged out-of-round
    decay pipe that does not satisfy UG80 is a serious and difficult
    safety concern that would have to be addressed through the formal
    safety review process of the vacuum vessel engineering note. For the
    contractor, if the Decay pipe after the concrete is poured does not
    satisfy UG-80 then it does not satisfy 3.1-A of the contract
    specification. Specification 3.1-A requires the decay pipe to be
    fabricated in accordance with the ASME Boiler and Pressure Vessel
    Code. The contractor is therefore obligated to repair or replace any
    damaged decay pipe. The contractor must be made to understand that
    the present contract requires that the entire decay pipe satisfy
    UG80.

37. ([Reviewer: R. Sanders]{.underline}) Plastic sleeves on Copper Pipe:
    The copper cooling pipes pass through the ring stiffeners placed
    every 210" along the length of the decay pipe. Plastic sleeves
    should be inserted into the holes in the stiffeners through which
    the copper pipes must pass. One end of the sleeve should have a lip
    to prevent it falling through. Perhaps the sleeves could be glued in
    place. Ideally the sleeves would have a snug fit around the copper
    pipe to help restrain its deflection.

38. ([Reviewer: R. Sanders]{.underline}) Future Larger Vacuums Pumps:
    Fermilab should not do anything to prohibit the installation of
    bigger vacuum pumps in the future if the need for them ever arises.
    What is done is done, but just don't back yourself into corner in
    case vacuum problems develop.

39. ([Reviewer: R. Sanders]{.underline}) Additional Ports: The decay
    pipe should have a drain at the bottom and a vent at the top. They
    could be welded off, but my strong personal preference is to run the
    pipes to an accessible location and install high quality valves such
    as Whitey ball valves that are vacuum tight and lock them shut. The
    drain valve could be used to drain water or vacuum pump oil from the
    decay pipe. The drain and vent valves together could be used to
    purge the decay pipe with nitrogen gas to dry it, if the need ever
    arose. Additional vacuum instrumentation ports (i.e. ¼" SS tubing
    runs) should be installed at the decay pipe top and bottom as well.
    Do not add instrumentation, but if vacuum problems arose additional
    instrumentation could be added to these ports to aid with the
    diagnostics. I would terminate these taps with high quality valves
    such as Nupro 4BKs and lock the valves closed. These ports may never
    be needed but this is a cheap thing to do. Minimizing the number of
    instrumentation ports is not a good practice especially on a on a ½
    mile long vacuum vessel.

40. Fatal leak Size in Decay Pipe: The vacuum pump will have a speed of
    400 cfm pumping down to 1 Torr. How big of a hole would it take in
    the decay pipe to overcome this vacuum pump? The leak rate would be
    400/760 = 0.526 scfm air. If I assume the hole in the decay pipe is
    a sharp edged orifice (flow coefficient of 0.62) with choked sonic
    flow of air with an upstream pressure of 14.3 psia (Fermilab typical
    ambient air pressure) and apply equations from the AGCO series 80
    catalogue; I find a hole size of .06" diameter in the decay pipe
    could cause such a leak. My calculations should be checked. That's
    about a 1/16" diameter hole - a pretty big hole - in the decay pipe
    that would overwhelm the vacuum pump. My gut feeling is that leaks
    much-much smaller than that would be found by the leak detection
    test specified in the contract section 3.7D for the decay pipe
    welds. I feel that NUMI is on the right track by closely monitoring
    how the leak testing is done. If the tests are done properly, it
    appears there should be little problem achieving the desired vacuum
    in the decay pipe. Knock on wood.

41. ([Reviewer: W. Smart]{.underline}) If you bring the 12 decay pipe
    cooling water copper tubes outside the shielding at each end and
    then manifold them outside the shielding, you can check for leaks
    and shut off a leaky tube without having to unpile shielding or work
    in an ultra-high radiation area. Taking this a step further, if you
    bring the tubes outside the shielding and then riight back into the
    shielding halfway along the decay pipe length, you could increase
    redundancy since you can then cross connect the good halfs of two
    leaky tubes.

42. ([Reviewer: W. Smart]{.underline}) The access port sticks outside
    the shielding, so we may get by with a bolted flange using organic
    or metal O-rings. If you design double seals with a pumpout between
    them (done in many places on the 15 foot Bubble Chamber) you can
    constantly verify that the flange is sealed.

43. ([Reviewer: R. Stanek]{.underline}) I second the suggestions made
    during the meeting for putting in a drain port, instrumentation
    lines, and upstream purge line (so that the pipe can be flow purged
    with dry air).

44. ([Reviewer: R. Stanek]{.underline}) Given the concern regarding
    galvanic corrosion, one might want to revisit the decision of
    putting the cooling pipes outside or inside the vessel. I would look
    at the choice in terms of failure modes, risk, possible negative
    long-term ramifications, cost and thermal performance. The project
    may decide it is easier to add the cooling to the inside of the tank
    after the contractor is done back filling but before heads are
    welded onto the vessel.

45. ([Reviewer: R. Stanek]{.underline}) If the copper water pipes are
    run external to the vessel, this implies an alignment of the
    stiffener rings down the entire length of the decay pipe to allow
    the copper pipes to pass through on a strait path. This should be
    part of the change order to the contractor (presently not in the
    contract specification).

46. ([Reviewer: R. Stanek]{.underline}) Look at the water-cooling system
    (treated like a RAW system) and assure that it is designed to allow
    easy maintenance and isolation of any given line (out of the 12)
    that might develop a leak. The water system should be instrumented
    to easily detect a leak should it occur.

47. ([Reviewer: R. Stanek]{.underline}) I am not familiar with the leak
    testing procedure proposed, however, I imagine that "certified"
    operators can make it work effectively. I would require that the
    operators prove to the project that they can detect a known leak
    (hole or weld crack) in a weld before accepting the verdict that the
    pipe is leak tight.

48. ([Reviewer: R. Stanek]{.underline}) Some thought might be given to
    other forms of NDE to help verify the soundness of the welding. Help
    might be available from other sources (such as ANL). I assume that
    the final weld specification (how each pass is performed) will be
    submitted to the project for approval.

49. ([Reviewer: R. Stanek]{.underline}) It would be beneficial to do an
    analysis of the vacuum system gas load. Expand on the calculation of
    pumping speed and conductance and look at outgas loads and the
    maximum leak rate that could be tolerated and still meet
    specification. The vacuum requirement should be revisited with the
    intention of setting the nominal and maximum vacuum levels in the
    decay pipe. The ability to use commercial equipment to separate and
    filter the water out of the oil of the vacuum pump should be
    investigated.

50. ([Reviewer: R. Stanek]{.underline}) Assuming one could ever imagine
    that the heads would get cut off, one would want to plan how to do
    it now. In order to cut off the head and prep the edge for welding,
    one probably wants to consider using a commercially available
    process (as was used in NWA for the D0 test cryostat). This requires
    a certain clear and flat space on the vessel for the rails and a
    minimum distance to the floor. The proposal to leave more room
    between the end of the concrete back fill and the edge of the pipe
    should be considered. This might also be beneficial for other
    reasons, such as ease of hooking up the water lines.

51. ([Reviewer: R. Stanek]{.underline}) There were several comments
    during the meeting about keeping the pipe round at its ends. This
    may or may not be a problem based on the design of the end
    attachments. Adding additional external stiffeners or temporary
    internal bracing was suggested. This should be looked at with
    respect to the short (one foot) ends on the decay pipe, future needs
    to cut off the ends and possible spring back of pipe end once the
    temporary support is removed.

52. ([Reviewer: R. Stanek]{.underline}) The steady state thermal
    analysis shows a maximum temperature of 66.8 ^o^C (152.2 ^o^F) while
    the specification (3.2.E) calls for a maximum operating temperature
    of 150 ^o^F. This should be examined in more detail. It was not
    clear that the temperature calculation took into account the effect
    of wrapping the copper pipe with PVC pipe.

# Design & Engineering of the Windows

# Presenter: E. Chi

1.  ([Reviewer: J. Anderson]{.underline}) Have calculations been
    performed to demonstrate the upstream decay pipe cap can
    structurally withstand the intended and accident condition beam
    power limits? More directly, is it possible to burn a hole through
    the upstream decay pipe cap causing a vacuum failure.

2.  ([Reviewer: S. Childress]{.underline}) I have significant concerns
    with the expressed intent to remove either of the large (6\'6\") end
    caps if there is initial need for leak diagnosis. It was a very good
    decision to weld these end caps - the parameters are very different
    than for the side access port(s). However, once welded this should
    be a final assembly. Access ports should provide the access option
    if vacuum problems for any part of the pipe must be addressed.

3.  ([Reviewer: M. Gerardi]{.underline}) What is the beam interaction
    and resultant dose rate on the upstream decay pipe window ? Does it
    adversely affect experimental data? It certainly affects groundwater
    and the sourounding dose rates.

4.  ([Reviewer: M. Gerardi]{.underline}) The more material used to
    strengthen the roundness at the ends of the pipe will likely
    increase beam interaction and increased activation.

5.  ([Reviewer: J. Klen]{.underline}) A drain plug should be added to
    the downstream endcap of the decay pipe.

6.  ([Reviewer: J. Klen]{.underline}) In both ends of the decay pipe, a
    temporary support spine could be welded inplace at the factory. This
    would insure the roundness is kept,within tolerance, inorder to
    simplify the installation of the endcaps.

7.  ([Reviewer: A. Para]{.underline}) Vacuum windows are quite
    elaborate, given the size of them. They are produced by Fermilab and
    welded to the installed decay pipe. The design is very robust and it
    does allow for possible distortions of the pipe. I am wandering if
    one could not simplify matters further by welding a thick stiffener
    ring to both extremities of the decay pipe (outside or perhaps even
    inside the pipe). Such a stiffener would prevent any distortions of
    the pipe and it may simplify the installation of the vacuum window.
    An inside ring of a considerable radial thickness can be even used
    to reduce the diameter of the vacuum window.

8.  ([Reviewer: A. Para]{.underline}) Vacuum testing/leaks etc was a
    matter of concern. I think the whole matter should be reconsidered.
    To put it bluntly: do we need any vacuum at all? The reason for
    evacuation of the decay volume is to reduce the amount of material
    traversed by pions before they decay. Pions have to traverse 50 m of
    air in the target chase and the entry window, which is equivalent to
    another 50 m of air. It means that any \'vacuum\' below, say, 50
    Torr will be acceptable. In fact, most of the particles decay within
    the first 100-150 meters of the decay pipe. It means that a
    \'vacuum\' of 300-400 Torr is quite adequate. Giving up vacuum
    completely and having an air tube would probably lead to some
    reduction of the flux (5%?) but it would simplify matters
    enormously: no windows, no vacuum leaks checking, no need for an
    access tunnel, air cooling if necessary, no vacuum pumps, etc.. This
    is worth a thought. Should we decide to have some vacuum, after all,
    we need it only in the first section (a third? a quarter?) of the
    decay volume. Air or vacuum in the second part would not produce any
    difference for the neutrino beam. I am not sure if this would
    simplify matters, but perhaps it is worthwhile to consider an
    intermediate vacuum window inside the decay volume. Even if this
    would be a neutral (cost-wise) it is perhaps a worth considering as
    it would offer us a possibility of installing some kind of a beam
    stopper there to reduce the muon induced backgrounds.

# Shielding & Installation Issues

[Presenter: B. Bernstein]{.underline}

1.  ([Reviewer: S. Childress]{.underline}) A very close coordination
    with Healy & CBI is needed during completion of design efforts and
    the installation process. Many questions remain:

    a.  How all details of the installation will be done?

    b.  Protection and isolation of cooling pipes during concrete pour?

    c.  Ensuring thousands of feet of sound pipe weld, and that these
        are not damaged during installation, concrete placement.

2.  ([Reviewer: S. Childress]{.underline}) I also have major
    reservations with an assessment made that, with existence of an
    initial major vacuum problem, a solution could be to try to
    overpower it with additional pumping and run. Overwhelmingly, vacuum
    problems only get worse - and frequently much worse. This type of
    solution would most likely eliminate diagnostic and repair options
    prior to radiation exposure.

3.  ([Reviewer: M. Gerardi]{.underline}) It still is somewhat
    disconcerting to hear that the estimates for dose rates are not yet
    complete. It is of course very difficult to review a number of the
    radiological aspects without estimates of activation levels.

4.  ([Reviewer: N. Grossman]{.underline}) Residual dose rates in the
    vicinity of the decay pipe access port and the decay pipe itself
    should be determined.

5.  ([Reviewer: J. Klen]{.underline}) Fermilab Safety Group could be
    contacted inorder to review possible access to the decay pipe,after
    it is completed. This review could suggest that the present man
    service hole be eliminated, enlarged or duplicated at both ends.

6.  ([Reviewer: J. Klen]{.underline}) The leak testing procedure is of
    some concern to me, I would like to see more information on this
    technique.

7.  ([Reviewer: P. Martin]{.underline}) On vacuum issues, the stated
    vacuum requirements aren't too stringent; however, I would strongly
    question the expressed opinion that small leaks would be OK as long
    as they could be overpowered with additional pumping. I think this
    is a serious mistake. An experiment this important and costly should
    not begin operations with any detectable leaks. Once beam has been
    delivered at any reasonable level of the NuMI expectations, it will
    be impossible to enter the decay pipe. The expected pumpdown rate
    should be calculated, and the vacuum should be datalogged during
    pumpdown to compare for agreement with the predictions, and if there
    are indications of leaks, they must be found and fixed prior to
    high-intensity operations.

8.  ([Reviewer: A. Para]{.underline}) Decay pipe installation is a
    responsibility of Healy. We seem not to have any details about the
    installation process, pouring of concrete etc.., although people
    have multiple concerns about several aspects here. I think it is
    very important to have relevant technical information, to make a
    review process worthwhile. I think that an engineer from Healy ought
    to be at the review. He should present the status of their
    preparation. If it is well advanced, then many issues can be
    clarified. If it is in its early stage, than it is possible that
    some trade-offs can be identified leading to a possible
    simplification of the installation aspects.

9.  ([Reviewer: A. Para]{.underline}) Contract includes various
    specifications and requirements concerning the decay pipe. They were
    not presented at the review and, moreover, there seems to be rather
    vague understanding what these requirements are. I think it is
    important to find out and review these requirements.

10. ([Reviewer: G. Rameika]{.underline}) My major concern after
    listening to this review was an apparent or perceived difficulty in
    the project knowing how S.A.Healy was actually going to install the
    system, where system includes the actual pipe, the cooling pipes,
    their PVC shields and finally the poured concrete.

11. ([Reviewer: R. Sanders]{.underline}) Damage of Copper Pipe Due to
    Falling Concrete: The contractor is required by the contract to
    install the copper cooling pipes in accordance with ANSI standards.
    The applicable standard here is the ANSI B31.3 piping code. If,
    while pouring concrete, the contractor damages, bends and twists the
    copper cooling pipe then the contractor must either demonstrate that
    the pressure rating of the damaged pipe is adequate in accordance
    with the ANSI B31.3 piping code or else replace the damaged pipe.
    Permanent bending of the copper pipe causes work hardening and
    plastic deformation which will affect the pressure rating of the
    pipe. By emphasizing this to the contractor, Fermilab also minimizes
    the chance of the copper pipes being twisted about to touch the
    decay pipe and causing galvanized corrosion.

12. ([Reviewer: R. Sanders]{.underline}) Concrete Pouring: In light of
    comments above, it is mandatory that the wet concrete be poured in
    such a way that the decay pipe and copper cooling pipes do not
    suffer permanent deformation or damage.

13. ([Reviewer: R. Sanders]{.underline}) Deflection of Copper Pipe: To
    prevent the copper pipe from deflecting and touching the decay pipe,
    consider keeping the copper cooling pipes under tension when pouring
    concrete. This will greatly minimize the lateral pipe deflection
    while being agitated by the swirling motion of the wet cement.
    Copper pipe of this type are sometimes pulled through holes in the
    ground much like pulling wires through conduit. It effect, you would
    be pulling the copper pipes into the straight paths you want through
    the wet cement. One could also consider using circular disks of
    plastic with annular holes that slide over the copper pipes. These
    spacers, placed at discrete intervals, would keep the copper pipes
    from touching the decay pipe. The axial position of the plastic
    spacers could be maintained with clamps (or tie-wraps???) around the
    copper pipes. The possibility of using commercial processes to coat
    the copper pipe with dielectric coating could be considered.

14. ([Reviewer: R. Sanders]{.underline}) Safety What-If questions: What
    would happen if the entire decay pipe filled with water? Also what
    would happen if the entire decay tunnel filled with water but not
    the decay pipe?

15. ([Reviewer: R. Sanders]{.underline}) Leak Testing Advice: If expert
    advice is needed on the solution film leak teak testing decay pipe,
    there are independent non destructive testing (NDT) labs and
    companies in the Chicago area. Argonne National Lab , many years
    ago, had a very good non-destructive testing group and for all I
    know, it may still be good. If you really don't trust the
    contractor, an outside NDT group could be brought in to do some spot
    checks on the leak testing.

16. ([Reviewer: R. Sanders]{.underline}) Decay Pipe Paint Job:
    Underground pipelines are common. The companies than put in
    underground natural gas and oil pipe lines certainly expect their
    pipelines to last much longer than 10 years. By applying the same
    technology used for these underground pipelines, it should be
    possible to get the decay pipe to last 10 years. Since there is
    concern about corrosion on the decay pipe, Fermilab should look at
    proven techniques used to prevent corrosion on underground pipes. I
    recommend reviewing the adequacy of contract specification 2.1 D for
    painting the decay pipe. Perhaps (and perhaps not) an additional
    coating should be applied to the decay pipe or the copper cooling
    tubes to prevent corrosion. For example if a dielectric coating is
    needed, there is a company BendTec (
    http://www.bendtec.com/coatline.html ) which among other things can
    paint and apply dielectric coatings to large underground pipes to
    prevent corrosion.

17. ([Reviewer: R. Stanek]{.underline}) There was not much time spent on
    cost or schedule for the project. Much of the decay pipe project is
    determined by the contract with SA Healy while there are other parts
    that are picked up by other WBS numbers (outfitting). In order to
    evaluate these estimates, additional information would be required,
    such as, the number and type of people assigned to each task and
    historical data on compliance to schedule.

18. ([Reviewer: R. Stanek]{.underline}) I sensed a heightened level of
    anxiety and concern over the initial cost and schedule for this
    project (and rightfully so). What I am worried about is that the
    same level of concern should be shown towards the long-term care,
    maintenance and possible repair of the system. The project needs to
    assure that design decisions made now, will not have adverse effects
    on long term operation and maintenance of the system. It might be
    worth doing a "what if or failure mode" analysis on this project in
    order to assure that possible failures do not result in extremely
    negative conditions (such as someone receiving a large radiation
    dose when doing maintenance/repair or loss of radioactive water to
    the environment). It is clear that project participants have this as
    one of their primary focus points in general, however, sometimes the
    pressure to "bring in the project on time and on budget" detracts
    from looking at the long-term aspects of decisions.

19. ([Reviewer: R. Stanek]{.underline}) Everyone seemed to agree that
    placing the decay pipe in the correct position and within the
    specified tolerance was crucial and that there would be no second
    chances (independent of what the contract states). I would suggest
    that some alignment monitoring or control happen when the pipe is
    first placed in position and that the Lab oversee and verify that
    the contractor is keeping the position of the pipe under control
    during the concrete fill. This would require some sort of monitoring
    during the back fill process. The Alignment Group seems to be quite
    active in the project so this may be in their plans already.

20. ([Reviewer: R. Stanek]{.underline}) It may be worth the effort to
    set up a partial model (scaled down version) to observe the proposed
    process of backfilling with concrete before they use it on the real
    thing. One might better understand issues such as the thermal
    distribution of a known heat input, cracking of the concrete,
    adhesion to the pipe, the effect of the concrete pour on things like
    pipe position, abrasion of the primer paint on the outside surface
    of the pipe, position and possible damage to the copper tubing, etc.